Search results for " Graphene"

showing 10 items of 102 documents

FLEXIBLE ELECTRODE BASED ON GOLD NANOPARTICLES AND REDUCED GRAPHENE OXIDE FOR URIC ACID DETECTION USING LINEAR SWEEP VOLTAMMETRY

2021

In this work, an electrochemical sensor for uric acid determination is shown with a preliminary study for its validation in real samples (milk and urine). Uric acid can be electrochemically oxidized in aqueous solutions and thus it is possible to obtain electrochemical sensors for this chemical by means of this electrooxidation reaction. Indium tin oxide coated on flexible polyethylene terephthalate substrate, modified with reduced graphene oxide and gold nanoparticles by co-electrodeposition, was used. Electrodeposition was performed at -0.8V vs SCE for 200 s. All samples were characterized by electron scan microscopy and electron diffraction spectroscopy. A careful investigation on the ef…

TK7885-7895Computer engineering. Computer hardwareMilkChemical engineeringSettore ING-IND/23 - Chimica Fisica ApplicataElectrochemical sensorTP155-156UrineUric acidUric acid Electrochemical sensors Reduced graphene oxide Gold nanoparticles Milk Urine
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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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Synthesis and characterisation of a ternary composite of polyaniline, reduced graphene-oxide and chitosan with reduced optical band gap and stable aq…

2019

A ternary composite comprising of p-toluene sulfonic acid doped polyaniline (PANI), chitosan and reduced graphene oxide (RGO) with stable aqueous dispersibility has been synthesised via oxidative polymerisation of aniline in chitosan/RGO dispersion. For comparison; PANI, PANI/chitosan and PANI/RGO composites were also synthesised using the same procedure. FTIR, Raman, XPS, XRD and UV-VIS confirmed the successful synthesis of the PANI and the composites. The aqueous dispersions of the PANI/chitosan and the ternary composites were found to be stable even after more than four months. The stability of the dispersion was attributed to the polycationic nature of the chitosan. The thermogravimetri…

Thermogravimetric analysisMaterials scienceReduced graphene-oxideComposite numberGeneral Physics and Astronomy02 engineering and technologySulfonic acid01 natural sciencesInverse Emulsion Polymerizationlaw.inventionAbsorptionChitosanCorrosion Protectionchemistry.chemical_compoundFabricationOptical band gaplaw0103 physical sciencesPolyanilineThermal stabilityChemical-Modification010302 applied physicschemistry.chemical_classification[PHYS]Physics [physics]ChitosanNanocompositeGrapheneSensorsTernary composite021001 nanoscience & nanotechnologylcsh:QC1-999Enhanced Electrical-ConductivityDoped polyanilinechemistryChemical engineeringFacile SynthesisAdsorption0210 nano-technologyTernary operationlcsh:Physics
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Noisy dynamics in long and short Josephson junctions

The study of nonlinear dynamics in long Josephson junctions and the features of a particular kind of junction realized using a graphene layer, are the main topics of this research work. The superconducting state of a Josephson junction is a metastable state, and the switching to the resistive state is directly related to characteristic macroscopic quantities, such as the current the voltage across the junction, and the magnetic field through it. Noise sources can affect the mean lifetime of this superconducting metastable state, so that noise induced effects on the transient dynamics of these systems should be taken into account. The long Josephson junctions are investigated in the sine-Gor…

Transient dynamickinkmean switching timeSettore FIS/02 - Fisica Teorica Modelli E Metodi Matematicigraphenebreathernoise induced effectlong Josephson junctiondynamic resonant activationGaussian noisenoise enhanced stabilitysine-Gordonshort Josephson junctionnonlinear relaxation timeJosephson junctionJosephson junction; sine-Gordon; Transient dynamics; noise induced effect; noise enhanced stability; dynamic resonant activation; stochastic resonant activation; resonant activation; soliton; breather; kink; Gaussian noise; non Gaussian noise; graphene; short Josephson junction; long Josephson junction; mean switching time; nonlinear relaxation time;stochastic resonant activationresonant activationnon Gaussian noisesoliton
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Investigation on Metal–Oxide Graphene Field-Effect Transistors With Clamped Geometries

2019

In this work, we report on the design, fabrication and characterization of Metal-Oxide Graphene Field-effect Transistors (MOGFETs) exploiting novel clamped gate geometries aimed at enhancing the device transconductance. The fabricated devices employ clamped metal contacts also for source and drain, as well as an optimized graphene meandered pattern for source contacting, in order to reduce parasitic resistance. Our experimental results demonstrate that MOGFETs with the proposed structure show improved high frequency performance, in terms of maximum available gain and transition frequency values, as a consequence of the higher equivalent transconductance obtained.

Work (thermodynamics)FabricationMaterials scienceTransconductanceOxide02 engineering and technologySettore ING-INF/01 - Elettronica01 natural scienceslaw.inventionchemistry.chemical_compoundlaw0103 physical sciencesElectrical and Electronic Engineering010302 applied physicsbusiness.industryGrapheneGraphene metal-oxide graphene field-effect transistors (MOGFETs) microwave transistors clamped geometries meandered graphene contacts.TransistorSettore ING-INF/02 - Campi Elettromagnetici021001 nanoscience & nanotechnologyElectronic Optical and Magnetic MaterialschemistryLogic gateParasitic elementOptoelectronics0210 nano-technologybusinessBiotechnologyIEEE Journal of the Electron Devices Society
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Carbon Dots Dispersed on Graphene/SiO2/Si: A Morphological Study

2019

Low-dimensional carbon materials occupy a relevant role in the field of nanotechnology. Herein, the authors report a study conducted by atomic force microscopy and Raman spectroscopy on the deposition of carbon dots onto graphene surfaces. The study aims at understanding if and how the morphology and the microstructure of chemical vapor deposited graphene on Si/SiO2 may change due to the interaction with the carbon dots. Potential alteration in the graphene's electrical properties might be detrimental for optoelectronic applications. The deposition of carbon dots dispersed in water and ethanol solvents are explored to investigate the effect of solvents with different fluidic properties. The…

atomic force microscopyMaterials scienceGrapheneAtomic force microscopychemistry.chemical_elementSurfaces and InterfacesCondensed Matter PhysicsSurfaces Coatings and FilmsElectronic Optical and Magnetic Materialslaw.inventionGraphene carbon dotssymbols.namesakechemistryChemical engineeringlawchemical vapor deposited graphenecarbon dotsRaman spectroscopyMaterials ChemistrysymbolsElectrical and Electronic EngineeringRaman spectroscopyCarbon
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$PT$-symmetric graphene under a magnetic field

2016

We propose a $PT$-symmetrically deformed version of the graphene tight-binding model under a magnetic field. We analyze the structure of the spectra and the eigenvectors of the Hamiltonians around the $K$ and $K'$ points, both in the $PT$-symmetric and $PT$-broken regions. In particular we show that the presence of the deformation parameter $V$ produces several interesting consequences, including the asymmetry of the zero-energy states of the Hamiltonians and the breakdown of the completeness of the eigenvector sets. We also discuss the biorthogonality of the eigenvectors, which {turns out to be} different in the $PT$-symmetric and $PT$-broken regions.

deformed grapheneGeneral Mathematicsmedia_common.quotation_subjectMathematicsofComputing_GENERALStructure (category theory)General Physics and AstronomyFOS: Physical sciencesDeformation (meteorology)01 natural sciencesAsymmetrySpectral linelaw.inventionTheoretical physicslawCompleteness (order theory)0103 physical sciencesMesoscale and Nanoscale Physics (cond-mat.mes-hall)biorthogonal eigenstate010306 general physicsSettore MAT/07 - Fisica MatematicaEigenvalues and eigenvectorsResearch ArticlesMathematical Physicsmedia_commonPhysicsCondensed Matter - Mesoscale and Nanoscale Physics010308 nuclear & particles physicsGrapheneGeneral Engineering-symmetric HamiltonianMathematical Physics (math-ph)Magnetic field
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Microwave gas sensor based on graphene aerogel for breath analysis

2022

Exhaled breath can be used for early detection and diagnosis of diseases, monitoring metabolic activity, and precision medicine. In this work, we design and simulate a microwave sensor in which thin graphene aerogels are integrated into rectangular microwave waveguides. Graphene aerogels are ideal sensing platforms for gases and volatile compounds as they combine extremely high surface-to-volume ratio and good electrical conductivity at RF and microwave frequencies. The latter is modified by exposure to different gases, and -when integrated into a waveguide- these changes result in significant shifts in transmission and reflection scattering parameters. We model the aerogel as a graphene gr…

gas sensors graphene aerogel microwave sensors rectangular waveguideSettore ING-INF/01 - Elettronica2022 IEEE International Symposium on Medical Measurements and Applications (MeMeA)
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Synthesis of a biocompatible aerogel based on graphene oxide and a modified polyethylene glycol

2016

The synthesis and self-assembly of a 3D aerogel built by graphene oxide (GO) and a modified polyethylene glycol (PEG) was achieved by a multi-step synthetic procedure, involving the preparation of an amino-terminated PEG (PEG-NH2) and the subsequent coupling with GO by carbodiimide in water, exploiting the carboxyl and epoxy moieties of GO and –NH2 terminations of the biopolymer. The resulting nanohybrid hydrogel was successively converted into an aerogel via dialysis plus freeze-drying [1] and fully characterized. FTIR, Raman, XPS, XRD and BET measurements were performed to confirm the successful modification for each reaction step, while morphological, mechanical and hemolytic tests were …

graphene oxide PEG aerogel graphene
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An Overview of Functionalized Graphene Nanomaterials for Advanced Applications

2021

Interest in the development of graphene-based materials for advanced applications is growing, because of the unique features of such nanomaterials and, above all, of their outstanding versatility, which enables several functionalization pathways that lead to materials with extremely tunable properties and architectures. This review is focused on the careful examination of relationships between synthetic approaches currently used to derivatize graphene, main properties achieved, and target applications proposed. Use of functionalized graphene nanomaterials in six engineering areas (materials with enhanced mechanical and thermal performance, energy, sensors, biomedical, water treatment, and c…

graphene quantum dotsComputer scienceGrapheneGeneral Chemical EngineeringgrapheneFunctionalized grapheneNanotechnologyReviewDrug releasefuel cellssensorsCatalysisNanomaterialslaw.inventionChemistrylawDrug releaseFuel cellsgraphene oxideTissue engineeringWater treatmentGeneral Materials ScienceQD1-999energyNanomaterials
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