Search results for "Oxide"

showing 10 items of 6424 documents

Long-Distance Magnetic Interaction of Exchange-Coupled Copper Dimers with Nitronyl Nitroxide and tert-Butyl Nitroxide Radicals

2009

To study long-distance magnetic interactions between exchange-coupled metal centers and coordinated radical moieties, two new homodimetallic Cu(II) complexes held together by the chelating ligand L(nPr) = N,N,N',N'-tetrakis(N-propyl-2-benzimidazolyl)-2-hydroxy-1,3-diaminopropane and additionally bridged by either a nitronyl nitroxide (NIT) or a tert-butyl nitroxide (NOA) radical-substituted benzoate have been prepared. The complexes have been investigated by X-ray crystallography, magnetic susceptibility measurements, electron paramagnetic resonance (EPR) spectroscopy, and density functional theory (DFT) calculations. For comparison additionally the related copper dimer with the bridging di…

Tert butylNitroxide mediated radical polymerizationChemistryRadicalchemistry.chemical_elementCopperInorganic ChemistryMetalvisual_artPolymer chemistryvisual_art.visual_art_mediumOrganic chemistryChelationPhysical and Theoretical ChemistryMagnetic interactionInorganic Chemistry
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The reduction of tris-dithiolene complexes of molybdenum(vi) and tungsten(vi) by hydroxide ion: kinetics and mechanism

2004

The kinetic study of the spontaneous reduction of some neutral tris-dithiolene complexes [ML3] of molybdenum(VI) and tungsten(VI), (L = S2C6H42−, S2C6H3CH32− and S2C2(CH3)22−; M = Mo or W) by tetrabutylammonium hydroxide in tetrahydrofuran-water solutions demonstrates that OH− is an effective reductant. Their reduction is fast, clean and quantitative. Depending upon both the molar ratio in which the reagents are mixed and the amount of water present, one- or two-electron reductions of these tris-dithiolene complexes were observed. If Bu4NOH is present in low concentration or/and at high concentrations of water, the total transformation of the neutral M(VI) complex into the monoanionic M(V) …

Tetrabutylammonium hydroxideLigandInorganic chemistrychemistry.chemical_elementTungstenInorganic ChemistryMetalchemistry.chemical_compoundchemistryNucleophileMolybdenumvisual_artvisual_art.visual_art_mediumHydroxideMoleculeDalton Trans.
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Characterization of the Oxidation of Magnetite Nanoparticles during Their Synthesis by Different Structural Analysis Techniques

2020

Water colloidal solutions of iron oxide nanoparticles coated with tetramethylammonium hydroxide were synthesized by co-precipitation methods. Dimensional analyses were accomplished by transmission ...

Tetramethylammonium hydroxide010401 analytical chemistryBiochemistry (medical)Clinical Biochemistry02 engineering and technology021001 nanoscience & nanotechnology01 natural sciencesBiochemistry0104 chemical sciencesAnalytical ChemistryCharacterization (materials science)chemistry.chemical_compoundMagnetite Nanoparticlessymbols.namesakeColloidchemistryChemical engineeringElectrochemistrysymbolsMagnetic nanoparticlesOxidation process0210 nano-technologyRaman spectroscopySpectroscopyIron oxide nanoparticlesAnalytical Letters
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On-line determination of bipyridylium herbicides in water by HPLC

1997

Selective on-line solid phase extraction (SPE) and liquid chromatography determination (HPLC) of diquat, paraquat and difenzoquat from environmental water samples has been accomplished with Graphitized Carbon Black (GCB) as both extraction and analytical columns. The method involved passing of 50 mL of water through a cartridge filled with Carbograph. In the elution step, the herbicides were transferred from the cartridge to the analytical column (Hypercarb) by mean of a gradient of pH 3 aqueous solution of tetramethylammonium hydroxide (TMAOH) and ammonium sulphate and methanol. Hypercarb columns were found to give a low probability of false positives for bypiridylium herbicides and are ve…

Tetramethylammonium hydroxideChromatographyAqueous solutionChemistryElutionOrganic ChemistryClinical BiochemistryExtraction (chemistry)BiochemistryHigh-performance liquid chromatographyAnalytical Chemistrychemistry.chemical_compoundDistilled waterSolid phase extractionMethanolChromatographia
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Characterization of acrylic resins used for restoration of artworks by pyrolysis-silylation-gas chromatography/mass spectrometry with hexamethyldisil…

2006

A procedure based on the technique of the pyrolysis-GC/MS has been applied, in this work, in order to determine the composition of synthetic acrylic resins employed in artworks. The method is based on the on line derivatization of these resins using hexamethyldisilazane (HMDS). Results obtained have been compared with those others from direct pyrolysis and in situ thermally assisted hydrolysis and methylation with tetramethylammonium hydroxide (TMAH). Sensitivity using HMDS as derivatising reagent is found similar to that from direct pyrolysis and methylation with TMAH. Better resolution of the most representative peaks has been also obtained. Additionally, this method reduces the formation…

Tetramethylammonium hydroxideChromatographyHot TemperatureResolution (mass spectrometry)SilylationOrganic ChemistryVarnishAcrylic ResinsGeneral MedicineBiochemistryGas Chromatography-Mass SpectrometryAnalytical Chemistrychemistry.chemical_compoundchemistryvisual_artPaintvisual_art.visual_art_mediumOrganosilicon CompoundsDerivatizationPyrolysisAcrylic resinArtAcrylic acidJournal of chromatography. A
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Analytical characterization of diterpenoid resins present in pictorial varnishes using pyrolysis–gas chromatography–mass spectrometry with on line tr…

2005

Abstract A procedure based on the technique of the pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) has been applied, in this work, in order to determine the composition of diterpenoid resin employed in art works. The method is based on the on line derivatization of these resins using hexamethyldisilazane (HMDS). Results obtained were compared with those previously reported in literature from Venice turpentine, Strasbourg turpentine, colophony, sandarac and Manila copal using this same method and with those others from in situ thermally assisted hydrolysis and methylation with tetramethylammonium hydroxide (TMAH). Canada balsam, copper resinate and Copaiba balsam have been also ana…

Tetramethylammonium hydroxideChromatographySilylationOrganic ChemistryVarnishSandaracGeneral Medicineengineering.materialSensitivity and SpecificityBiochemistryGas Chromatography-Mass SpectrometryAnalytical ChemistryPyrolysis–gas chromatography–mass spectrometrychemistry.chemical_compoundchemistryCanada balsamvisual_artPaintengineeringvisual_art.visual_art_mediumOrganic chemistryGas chromatographyDiterpenesDerivatizationJournal of Chromatography A
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Essential oil compositions of Teucrium fruticans, T. scordium subsp. scordioides and T. siculum growing in Sicily and Malta

2020

In the present study, the chemical composition of the essential oils from the aerial parts of Teucrium fruticans L. collected in Sicily and Malta, Teucrium scordium subsp. scordioides (Schreb.) Arcang. and Teucrium siculum (Raf.) Guss., collected in Sicily, were evaluated by GC-MS. The main volatile components of both T. fruticans collections were germacrene D (29.4% and 50.0%), (E)-β-caryophyllene (19.6% and 21.9%), and 1-octen-3-ol (19.7% and 7.4%); T. scordium subsp. scordioides essential oil was rich in caryophyllene oxide (25.8%), α-pinene (19.4%) and β-pinene (8.5%); T. siculum essential oil was rich in (E)-β-caryophyllene (30.9%), 1-octen-3-ol (9.0%), α-humulene (8.6%) and germacrene…

Teucrium ssp.Organic ChemistryVolatile componentsSettore CHIM/06 - Chimica OrganicaPlant ScienceBiology1-Octen-3-olbiology.organism_classificationBiochemistryAnalytical Chemistrylaw.inventionChemotaxonomyTeucrium(E)-β-CaryophylleneCaryophyllene oxidelawBotanyTeucrium scordiumSettore BIO/15 - Biologia FarmaceuticaGermacrene DEssential oilGermacrene DNatural Product Research
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Rapid and eco-friendly synthesis of graphene oxide-silica nanohybrids

2014

The increasing interest in Graphene oxide (GO) is due to many issues: the presence of both sp2-conjugated atoms and oxygen-containing functional groups provides a strong hydrophilicity and the possibility to further functionalize it with other molecules (i.e. π-π interactions covalent attachment etc.) [1]. Furthermore since the GO is biocompatible and noncytotoxic many studies have been recently focused on the development of GO-based nanodevices for bioimaging DNA detection drug delivery. Due to their low cytotoxicity and large internal surface area silica nanoparticles have been taken into account as promising material for biolabeling and drug loading/delivery. Particular consideration has recently been demonstrated for GO-silica composites because of the potentialities for electrical applications their chemical inertia and stability toward ions exposure. The possibility to combine the extraordinary properties of GO and silica offers several advantages for the realization of nanoprobes for biological applications and of biosensor [12]. The strategy for the fabrication of GO-nanosilica nanohybrids can be schematized as follows: (i) synthesis of GO by oxidizing graphite powder with the method described by Marcano et al. [3] (ii) Preparation of oxygen-loaded silica nanoparticles by thermal treatments in controlled atmosphere in order to induce high NIR emission at 1272 nm from high purity silica nanoparticles. (iii) preparation of GrO-silica nanohybrid films via rapid solvent casting in water. The nanohybrids were tested by XPS FTIR Raman analysis UV photoluminescence analysis TGA Zeta potential measurements electrical tests AFM and SEM. Several nanohybrids were prepared by combining two different typologies of GO and two different samples of silica.
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Impact of transparent conductive oxide on the admittance of thin film solar cells

2010

Abstract The impact of transparent electrically conducting oxide (TCO) on the admittance measurements of thin film p–i–n a-Si:H solar cells was investigated. Admittance measurements on solar cell devices, with different area and geometry, in a wide range of frequencies and biases were performed. The admittance measurements of the investigated solar cells, which use the TCO as an electrical contact, showed that the high frequency admittance per area unit depends on the area. This effect increases both with the probe frequency and the size of the solar cells. Transmission line model valid for strip geometry which explains how the resistivity of the TCO layer impacts the measured admittance of…

Theory of solar cellsMaterials scienceAdmittanceintegumentary systemEquivalent series resistancebusiness.industryCondensed Matter PhysicsCapacitanceElectronic Optical and Magnetic Materialslaw.inventionTransparent conductive oxide (TCO)Admittance CV measurementTransmission linesThin film solar cellsa-Si:H Series resistanceOpticslawParasitic elementSolar cellMaterials ChemistryElectrical and Electronic EngineeringThin filmbusinessTransparent conducting filmSolid-State Electronics
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Optimizing the Binding Energy of the Surfactant to Iron Oxide Yields Truly Monodisperse Nanoparticles.

2018

Despite the great progress in the synthesis of iron oxide nanoparticles (NPs) using a thermal decomposition method, the production of NPs with low polydispersity index is still challenging. In a thermal decomposition synthesis, oleic acid (OAC) and oleylamine (OAM) are used as surfactants. The surfactants bind to the growth species, thereby controlling the reaction kinetics and hence playing a critical role in the final size and size distribution of the NPs. Finding an optimum molar ratio between the surfactants oleic OAC/OAM is therefore crucial. A systematic experimental and theoretical study, however, on the role of the surfactant ratio is still missing. Here, we present a detailed exper…

Thermal decompositionDispersityIron oxideNanoparticle02 engineering and technologySurfaces and Interfaces010402 general chemistry021001 nanoscience & nanotechnologyCondensed Matter Physics01 natural sciences0104 chemical scienceschemistry.chemical_compoundOleic acidPulmonary surfactantchemistryChemical engineeringOleylamineElectrochemistryGeneral Materials Science0210 nano-technologySpectroscopyIron oxide nanoparticlesLangmuir : the ACS journal of surfaces and colloids
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