Search results for "Magnetic materials"

showing 10 items of 4679 documents

Reversible stimulus-responsive Cu(i) iodide pyridine coordination polymer

2015

We present a structurally flexible copper–iodide–pyridine-based coordination polymer showing drastic variations in its electrical conductivity driven by temperature and sorption of acetic acid molecules. The dramatic effect on the electrical conductivity enables the fabrication of a simple and robust device for gas detection. X-ray diffraction studies and DFT calculations allow the rationalisation of these observations.

chemistry.chemical_classificationFabricationChemistryCoordination polymerIodideMetals and AlloysNanotechnologySorptionQuímicaGeneral ChemistryAcetic acidPhotochemistryCatalysisSurfaces Coatings and FilmsElectronic Optical and Magnetic Materialschemistry.chemical_compoundAcetic acidCopper iodide pyridine coordination polymerElectrical resistivity and conductivityPyridineMaterials ChemistryCeramics and CompositesMoleculeChemical Communications
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Fast proton conduction in hydrogen bonded microheterogeneous systems: Bis(2-ethylhexyl)phosphoric acid/N-methyl formamide liquid mixtures

2009

Structural and dynamical properties of bis(2-ethylhexyl)phosphoric acid (HDEHP)/N-methyl formamide (NMF) liquid mixtures in the whole composition range have been investigated by Fourier Transform Infrared spectroscopy (FT-IR), X-rays Diffraction (XRD), and AC complex impedance spectroscopy. Driven by hydrogen bond interactions among HDEHP PO(4)H group and NMF CO and NH groups, and also by steric effects among the HDEHP alkyl chains, the system microstructure is mainly characterized by the coexistence of spatially separated hydrophilic and hydrophobic nanodomains showing local organization and short-range order. The evolution of this structural feature with system composition has been highli…

chemistry.chemical_classificationFormamideHydrogen bondAnalytical chemistryInfrared spectroscopyFast proton conduction systems Microheterogeneous liquid mixtures Bis(2-ethylhexyl)phosphoric acid N-methyl formamidePercolation thresholdSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsBiomaterialschemistry.chemical_compoundColloid and Surface ChemistrychemistryX-ray crystallographyFourier transform infrared spectroscopyPhosphoric acidAlkylSettore CHIM/02 - Chimica FisicaJournal of Colloid and Interface Science
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Mimicking photosynthesis: covalent [60]fullerene-based donor–acceptor ensembles

2004

Abstract Within the context of exploring photophysical properties of [60]fullerene-based donor–acceptor ensembles, we highlight in this contribution an approach towards the synthesis of a novel series of donor-bridge-acceptor, C 60 –wire– ex TTF , ensembles that incorporate p -phenylenevinylene oligomers, in which the conjugation length has been systematically increased, as bridges that connect π-extended tetrathiafulvalenes (exTTF) (electron donor) with [60]fullerene (electron acceptor). This molecular design allows probing the effects of distance and rate, at which electron transfer processes occur, as well as the molecular-wire behavior of the oligo-PPV fragments.

chemistry.chemical_classificationFullereneChemistryMechanical EngineeringMetals and AlloysContext (language use)Electron donorSettore CHIM/06 - Chimica OrganicaElectron acceptorCondensed Matter PhysicsPhotochemistryPhotoinduced electron transferElectronic Optical and Magnetic MaterialsMolecular wireElectron transferchemistry.chemical_compoundFullerene derivativesMechanics of MaterialsMaterials ChemistryTetrathiafulvaleneSynthetic Metals
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Iodine and mercury resonance lamps for kinetics experiments and their spectra in the far ultraviolet

2000

Electrodeless iodine and mercury iodide radio-frequency discharge lamps have been made to provide intense sources of resonance radiation of iodine and mercury in the 183-253 nm region. Production technology and emission spectra in the ultraviolet and vacuum ultraviolet regions are described. Both lamps (iodine and mercury iodide) are designed and used for monitoring the iodine 2P1/2 (206.163 nm) and 2P3/2 (183.038 nm) level population kinetics after flash photolysis of I2 or other precursor molecules in laboratory experiments. The technique is suitable for the investigation of the gas phase reaction kinetics following the photolysis of I2 in the presence of O3.

chemistry.chemical_classificationGas-discharge lampAcoustics and UltrasonicsKineticsPhotodissociationIodideAnalytical chemistrychemistry.chemical_elementCondensed Matter PhysicsIodinemedicine.disease_causeSurfaces Coatings and FilmsElectronic Optical and Magnetic Materialslaw.inventionMercury (element)chemistrylawmedicineFlash photolysisUltravioletJournal of Physics D: Applied Physics
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Multifunctional polymer-derivatized γ-Fe2O3 nanocrystals as a methodology for the biomagnetic separation of recombinant His-tagged proteins

2008

Abstract Multifunctional polymer-derivatized superparamagnetic iron oxide (γ-Fe2O3) nanoparticles were prepared for biomagnetic separation of histidine-tagged recombinant proteins building up a faster and efficient method for protein separation by making use of their intrinsic magnetic properties. Using polymer bound γ-Fe2O3 nanocrystals, a 6× histidine-tagged recombinant protein (silicatein) with a molecular weight of 24 kDa has been isolated and purified. The supermagnetic iron oxide nanocrystals were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), SQUID and Mossbauer and the polymer functionalization of the γ-Fe2O3 nanocrystals was monitored by UV–vi…

chemistry.chemical_classificationGel electrophoresisMaterials scienceIron oxideNanoparticlePolymerCondensed Matter PhysicsElectronic Optical and Magnetic Materialschemistry.chemical_compoundNuclear magnetic resonancechemistryChemical engineeringProtein purificationMicroscopyHigh-resolution transmission electron microscopySuperparamagnetismJournal of Magnetism and Magnetic Materials
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Properties and interactions – melting point of tri­bromo­benzene isomers

2021

The melting points of tri­bromo­benzene isomers are correlated with the number, nature and distribution of intermolecular interactions in their structures.

chemistry.chemical_classificationHalogen bondtribromobenzene isomersChemistryIntermolecular forcemelting pointMetals and AlloysClose-packing of equal spheresResearch PapersAtomic and Molecular Physics and OpticsElectronic Optical and Magnetic MaterialsCrystalmolecular symmetryCrystallographynoncovalent interactionsMaterials ChemistryMelting pointMolecular symmetrystructure-property relationshipNon-covalent interactionsMoleculehalogen bondActa Crystallographica Section B-Structural Science Crystal Engineering and Materials
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Effects of isotopic substitution on the conformational properties of polymeric aqueous solutions

2000

Abstract This work deals with a side-by-side comparison between the PEO conformational properties in H 2 O and D 2 O. The gyration radius, evaluated by SANS, the hydrodynamic radius, evaluated by PCS, and the Raman D-LAM band analysis furnish valuable information on the structural arrangement of the molecules. The findings clearly show different behavioural properties of the polymer in H 2 O and D 2 O.

chemistry.chemical_classificationHydrodynamic radiusMaterials scienceRadiusPolymerCondensed Matter PhysicsGyrationSmall-angle neutron scatteringElectronic Optical and Magnetic Materialssymbols.namesakechemistrysymbolsMoleculePhysical chemistryElectrical and Electronic EngineeringRaman spectroscopyRaman scattering
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Diferrocenyl tosyl hydrazone with an ultrastrong NHFe hydrogen bond as double click switch.

2014

The intramolecular NH⋯Fe hydrogen bond in diferrocenyl hydrazone 2 raises the barrier for intramolecular electron transfer in its mixed-valent cation 2+ and is only disrupted by double oxidation to 22+.

chemistry.chemical_classificationHydrogen bondMetals and AlloysHydrazoneGeneral ChemistryPhotochemistryCatalysisSurfaces Coatings and FilmsElectronic Optical and Magnetic Materialschemistry.chemical_compoundElectron transferchemistryTosylIntramolecular forceMaterials ChemistryCeramics and CompositesChemical communications (Cambridge, England)
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The effect of disorder on optical spectra of conjugated polymers

1993

Abstract Using the semi-empirical parametrization of the Pariser-Parr-Pople model we determine the excitonic states in conjugated polymers. The employed parameters correspond to a moderate strength of the long-range Coulomb interaction. In order to take the disorder into account, the nearest-neighbour transfer matrix elements are chosen according to a random distribution. Averaging the results over a large number of chains of 100 sites, which are known to be sufficiently long so that finite-size effects become negligible, we obtain the linear and third-order nonlinear optical susceptibilities. With increasing disorder the linear absorption, the two-photon absorption and the third-harmonic g…

chemistry.chemical_classificationImaginationChemistryMechanical Engineeringmedia_common.quotation_subjectMetals and AlloysPolymerCondensed Matter PhysicsAsymmetryMolecular physicsTransfer matrixSpectral lineElectronic Optical and Magnetic MaterialsNuclear magnetic resonanceMechanics of MaterialsMaterials ChemistryCoulombAbsorption (electromagnetic radiation)Parametrizationmedia_commonSynthetic Metals
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Maghemite polymer nanocomposites with modulated magnetic properties

2007

A method is presented for the production of maghemite polymer nanocomposites with modulated magnetic properties. Magnetic nanocomposites prepared using this method show regular variation in the magnetic blocking temperature from 2 K to 300 K, and variation in the saturation magnetization from 0 to 50 emu g � 1 (Fe2O3). The method is based on the in situ formation of maghemite nanoparticles in nitrogen-base polymer matrixes. The particle size can be varied regularly from 1.5 nm to 16 nm by changing the ratio of iron loading in the polymer and/or the Fe(II)/Fe(III) ratios. The particles are isolated and uniformly distributed within the matrix. The mate

chemistry.chemical_classificationIn situNanocompositeMaterials sciencePolymers and PlasticsPolymer nanocompositeMetals and AlloysMaghemiteNanoparticlePolymerengineering.materialElectronic Optical and Magnetic MaterialsNuclear magnetic resonancechemistryChemical engineeringCeramics and CompositesengineeringParticle sizeActa Materialia
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