Search results for " GRAPHITE"

showing 10 items of 30 documents

Real-time manipulation of ZnO nanowires on a flat surface employed for tribological measurements: Experimental methods and modeling

2012

Elastic and tribological properties of zinc oxide nanowires (NWs) on Si wafer and highly oriented pyrolytic graphite (HOPG) are experimentally investigated and theoretically interpreted. Measurements are performed inside a scanning electron microscope (SEM) using real-time manipulation technique that enables two possible ways of data registration: “external” force registration with quartz tuning fork (QTF) based sensor and “internal” force registration utilizing in situ observed elastic deformation of NWs. Young modulus is determined by loading half-suspended NW at its free end and then employed for the following tribological experiments. Maximal static friction force is estimated when NW i…

Range (particle radiation)Materials scienceScanning electron microscopeRelaxation (NMR)NanowireYoung's modulusNanotechnologyTribologyCondensed Matter PhysicsElectronic Optical and Magnetic Materialssymbols.namesakeHighly oriented pyrolytic graphitesymbolsWaferComposite materialphysica status solidi (b)
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Monolayer Structure of Arachidic Acid on Graphite

2010

The self-assembly of arachidic acid (C(19)H(39)COOH) at the liquid solid interface between 1-phenyloctane (C(6)H(5)(CH(2))(7)CH(3)) and highly oriented pyrolytic graphite (HOPG) is studied by scanning tunneling microscopy (STM) to identify the structure of the monomolecular film. We observe the formation of highly ordered domains with molecules oriented in three different orientations compatible with the symmetry of the HOPG substrate, a spontaneous enantiomeric separation of the pro-chiral molecules, and reveal structural details with submolecular resolution. To determine the surface unit cell with an intrinsic calibration to the substrate atomic structure, the intermolecular distance is p…

Resolution (electron density)Substrate (electronics)530Surfaces Coatings and FilmsElectronic Optical and Magnetic Materialslaw.inventionCrystallographychemistry.chemical_compoundGeneral EnergyHighly oriented pyrolytic graphitechemistrylawMonolayerArachidic acidMoleculeGraphitePhysical and Theoretical ChemistryScanning tunneling microscope
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Nanocomposites of epoxy resin with graphene nanoplates and exfoliated graphite: Synthesis and electrical properties

2014

Nanocomposites are nowadays one of the most promising materials. Among different fillers, e.g. carbon nanotubes and silicon carbide nanowires (NWSiC), already used with epoxy resin matrices, graphene exfoliated graphite (EG) and graphene nanoplates have some characteristics that make them unique for electromagnetic shielding materials. However, there is still an unresolved problem of proper dispersion that will ensure the homogeneity of samples. To overcome this drawback, inorganic fibres were proposed. An amount of 0.25 phr (parts per hundred; filler content presented as wt.% of the whole polymeric matrix) NWSiC, added to the EG 1 phr/epoxy resin sample, efficiently prevents filler agglome…

Settore ING-IND/22 - Scienza E Tecnologia Dei Materialinanocompositeexfoliated graphitecombustion synthesisilicon carbide nanowiresSettore CHIM/02 - Chimica Fisica
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Graphite-supported TiO2 for 4-nitrophenol degradation in a photoelectrocatalytic reactor

2009

WOS: 000274769500044

Settore ING-IND/24 - Principi Di Ingegneria ChimicaAnataseMaterials scienceAqueous solutionScanning electron microscopePhotoelectrocatalytic degradation photoelectrocatalytic reactor graphite supported TiO2 4-nitropheol oxidationGeneral Chemical EngineeringContinuous reactorAnalytical chemistryGraphite-Supported Tio2General Chemistry4 Nitrophenol OxidationIndustrial and Manufacturing EngineeringAmorphous solidPhotoelectrocatalytic ReactorElectrodeEnvironmental ChemistrySettore CHIM/07 - Fondamenti Chimici Delle TecnologieGraphiteEnergy sourcePhotoeletrocatalytic DegradationChemical Engineering Journal
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Electron transfer mechanism in Shewanella loihica PV-4 biofilms formed at graphite electrode

2012

Abstract Electron transfer mechanisms in Shewanella loihica PV-4 viable biofilms formed at graphite electrodes were investigated in potentiostat-controlled electrochemical cells poised at oxidative potentials (0.2 V vs. Ag/AgCl). Chronoamperometry (CA) showed a repeatable biofilm growth of S. loihica PV-4 on graphite electrode. CA, cyclic voltammetry (CV) and its first derivative shows that both direct electron transfer (DET) mediated electron transfer (MET) mechanism contributes to the overall anodic (oxidation) current. The maximum anodic current density recorded on graphite was 90 μA cm − 2 . Fluorescence emission spectra shows increased concentration of quinone derivatives and riboflavi…

ShewanellaElectroactive biofilmBioelectric Energy SourcesExtracellular Electron TransferRiboflavinInorganic chemistryBiophysicsElectrochemical cellElectron TransportElectron transferGraphite electrodeElectrochemistryGraphitePhysical and Theoretical ChemistryElectrodesMicroscopy ConfocalChemistryQuinonesBiofilmmediated electron transferElectrochemical TechniquesGeneral MedicineChronoamperometryAnodeSpectrometry FluorescenceShewanella loihica PV- 4Extracellular Electron Transfer; Shewanella loihica PV- 4; Electroactive biofilms; Graphite electrode; mediated electron transferBiofilmsMicroscopy Electron ScanningGraphiteDifferential pulse voltammetryCyclic voltammetryOxidation-ReductionBioelectrochemistry
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Synthesis and helical supramolecular organization of discotic liquid crystalline dibenzo[hi,st]ovalene

2019

Dibenzo[hi,st]ovalene (DBOV) has emerged as a new polycyclic aromatic hydrocarbon (PAH) with intriguing optical properties with strong red emission. Nevertheless, DBOV derivatives thus far synthesized either had mesityl groups that hinder the pi-pi stacking of the aromatic cores or showed low solubility, and the self-assembly of DBOVs has not been investigated. In this work, two 3,4,5-tris(dodecyloxy)phenyl (TDOP) groups are introduced at the meso-positions of DBOV in order to enhance its solubility without compromising the intermolecular interactions. The obtained DBOV-TDOP forms at elevated temperatures a discotic liquid crystalline phase. Due to pi-pi-stacking interactions as well as loc…

TechnologyMaterials scienceMaterials ScienceStackingSupramolecular chemistryMaterials Science Multidisciplinary02 engineering and technologyOvalene010402 general chemistry01 natural sciencesPhysics Appliedchemistry.chemical_compoundHighly oriented pyrolytic graphitePhase (matter)Materials ChemistrySide chainCHARGE-TRANSPORTScience & TechnologyBilayerPhysicsHEXA-PERI-HEXABENZOCORONENESGeneral Chemistry021001 nanoscience & nanotechnology0104 chemical sciencesCrystallographychemistryMOBILITYPhysical SciencesAlkoxy groupDISK-LIKE MOLECULES0210 nano-technology
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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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Effect of graphene nanoplatelets on the dielectric permittivity and segmental motions of electrospun poly(ethylene-co-vinyl alcohol) nanofibers

2021

The influence of the addition of graphene nanoplatelets (GNPs) on the intra/inter – molecular segmental motions of poly(ethylene-co-vinyl alcohol) (EVOH) was assessed by means of dielectric thermal analysis (DETA). The relaxation spectra were studied in terms of the dielectric permittivity (ε′) and the dielectric loss tangent (tan δ) at wide ranges of frequency (from 10−2 to 107 Hz) and temperature (from -150 to 140 °C). Two relaxation zones were disthinguished. Below the glass transition temperature (Tg), two β-relaxations were observed, which are characteristic local modes of mobility of the EVOH side groups, and related to the influence of the different surroundings of ethylene or vinyl …

Vinyl alcoholEngineeringTECNOLOGIA DE ALIMENTOSPolymers and PlasticsSegmental cooperativityDielectric permittivityPoly(ethylene-co-vinyl alcohol) EVOH02 engineering and technology010402 general chemistry01 natural scienceschemistry.chemical_compoundExfoliated graphite nano-plateletsRegional developmentDielectric permittivityDynamic fragilityMaterials ChemistryPoly ethylenebusiness.industryBusiness administrationPolymer nanocompositesEconomic support021001 nanoscience & nanotechnologyCondensed Matter Physics0104 chemical scienceschemistryMechanics of MaterialsMAQUINAS Y MOTORES TERMICOSChristian ministry0210 nano-technologybusinessGraphene nanoplatelets GNPsPolymer Degradation and Stability
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Effect of pressure on the electrochemical generation of hydrogen peroxide in undivided cells on carbon felt electrodes

2017

The electrochemical generation of H2O2can be performed in aqueous solutions by cathodic reduction at carbonaceous cathodes of oxygen coming from air. The performances of the process in terms of concentration of H2O2and current efficiency (CE) are limited by the low solubility of oxygen in water at atmospheric pressure. However, the solubility of oxygen can be increased upon enhancing the air pressure. The effect of pressure on the electrochemical generation of hydrogen peroxide was studied in undivided cells changing the pressure from 0 to 30 relative bar and the current density from 1 to 100 mA cm−2. Simple carbon felt and compact graphite cathodes were first used. A dramatic effect of…

carbon blackGeneral Chemical EngineeringInorganic chemistrychemistry.chemical_elementhydrogen peroxide02 engineering and technologyElectrolyte010402 general chemistryElectrochemistry01 natural sciencesOxygenchemistry.chemical_compoundcarbon feltmodified cathodeElectrochemistryChemical Engineering (all)GraphiteHydrogen peroxideElectro generationAtmospheric pressureCarbon blackSettore ING-IND/27 - Chimica Industriale E Tecnologica021001 nanoscience & nanotechnologyCompact graphite0104 chemical scienceschemistryair pressure0210 nano-technologyBar (unit)
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Electron-phonon interaction in flat-band superconductivity

2017

Parhaiten tunnettu suprajohtavuuden syntymekanismi perustuu fononien välittämään vetovoimaan elektronien välillä. Tässä tutkielmassa tutkin fononien välittämää suprajohtavuutta systeemeissä, jossa elektronivyöt ovat tasomaisia. Tasovyöllä elektronien dispersio on erittäin heikko, jolloin tilatiheys on tavanomaista suurempi. Tämän takia suprajohtavuus tasovyöllä on tavanomaista voimakkaampi silloin kun elektronien välinen vetovoima on heikko. Eliashbergin teoria on elektroni–fononi-suprajohtavuuden teoria, joka ottaa luonnollisella tavalla fononien äärellisen nopeuden huomioon elektronien välisessä vuorovaikutuksessa. Pohjustuksena tasovyösuprajohtavuuteen perehdyn Eliashbergin teoriaan ensi…

suprajohtavuussuperconductivityflat bandelektroni-fononi-vuorovaikutusromboedrinen grafiittielektronitpintatilattasovyörombohedral graphiteEliashbergin teoriaelectron-phonon interactionsurface statesEliashberg theoryfononit
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