Search results for "nanotecnologia"
showing 10 items of 67 documents
Optimizing Energy Transduction of Fluctuating Signals with Nanofluidic Diodes and Load Capacitors
2018
[EN] The design and experimental implementation of hybrid circuits is considered allowing charge transfer and energy conversion between nanofluidic diodes in aqueous ionic solutions and conventional electronic elements such as capacitors. The fundamental concepts involved are reviewed for the case of fluctuating zero-average external potentials acting on single pore and multipore membranes. This problem is relevant to electrochemical energy conversion and storage, the stimulus-response characteristics of nanosensors and actuators, and the estimation of the accumulative effects caused by external signals on biological ion channels. Half-wave and full-wave voltage doublers and quadruplers can…
Continuous Broadband MWP True-Time Delay with PbS-PMMA and -SU8 waveguides
2016
[EN] A new microwave true-time delay (TTD) photonic unit based on the dispersion of PbS colloidal quantum dots (QDs) in a Polymethyl methacrylate (PMMA) and the SU8 photoresist is presented. With this aim, the PbS-PMMA and PbS-SU8 nanocomposites are integrated on a silicon platform in the form of a planar and ridge waveguides, respectively. When PbS QDs on those structures are pumped below their band-gap, a phase shift and a temporal delay in an optically conveyed (at 1550 nm) microwave signal is performed. The results of these devices show potential benefits over current TTD technologies, since the proposed photonic waveguide structures allows real-time adjustment of the temporal delay by …
Polarized and resonant Raman spectroscopy on single InAs nanowires
2011
We report polarized Raman scattering and resonant Raman scattering studies on single InAs nanowires. Polarized Raman experiments show that the highest scattering intensity is obtained when both the incident and analyzed light polarizations are perpendicular to the nanowire axis. InAs wurtzite optical modes are observed. The obtained wurtzite modes are consistent with the selection rules and also with the results of calculations using an extended rigid-ion model. Additional resonant Raman scattering experiments reveal a redshifted E1 transition for InAs nanowires compared to the bulk zinc-blende InAs transition due to the dominance of the wurtzite phase in the nanowires. Ab initio calculatio…
Phonon-plasmon coupling in Si doped GaN nanowires
2016
Abstract The vibrational properties of silicon doped GaN nanowires with diameters comprised between 40 and 100 nm are studied by Raman spectroscopy through excitation with two different wavelengths: 532 and 405 nm. Excitation at 532 nm does not allow the observation of the coupled phonon–plasmon upper mode for the intentionally doped samples. Yet, excitation at 405 nm results in the appearance of a narrow peak at frequencies close to that of the uncoupled A 1 (LO) mode for all samples. This behavior points to phonon–plasmon scattering mediated by large phonon wave-vector in these thin and highly doped nanowires.
Design of Bistable Gold@Spin‐Crossover Core–Shell Nanoparticles Showing Large Electrical Responses for the Spin Switching
2019
<p>A simple protocol to prepare core-shell gold@spin-crossover (Au@SCO) nanoparticles (NPs) based on the 1D spin-crossover [Fe(Htrz)<sub>2</sub>(trz)](BF<sub>4</sub>) coordination polymer is reported. The synthesis relies on a two-step approach consisting on a partial surface ligand substitution of the citrate-stabilized Au NPs followed by the controlled growth of a very thin layer of the SCO polymer. As a result, colloidally stable core@shell spherical NPs of 19 nm in size exhibiting a narrow distribution in sizes have been obtained, revealing a switchable SCOshell of <i>ca.</i>4 nm. Temperature-dependent charge transport measurements of an electri…
Molecular magnetism: from chemical design to spin control in molecules, materials and devices
2019
The field of molecular magnetism is rapidly evolving towards the use of magnetic molecules and molecule-based magnetic materials in physics-driven and nanotechnology-driven fields, in particular molecular spintronics, quantum technologies, metal–organic frameworks (MOFs) and 2D materials. In molecular spintronics, the goal is the development of a new generation of spintronic devices based on molecular materials or, in the longer term, on one or a few molecules. In the area of quantum technologies, the milestones reached in the design of molecular spin qubits with long quantum coherence times and in the implementation of quantum operations have raised expectations for the use of molecular sp…
WS2 2D Semiconductor Down to Monolayers by Pulsed-Laser Deposition for Large-Scale Integration in Electronics and Spintronics Circuits
2020
International audience; We report on the achievement of a large-scale tungsten disulfide (WS2) 2D semiconducting platform derived by pulsed-laser deposition (PLD) on both insulating substrates (SrTiO3), as required for in-plane semiconductor circuit definition, and ferromagnetic spin sources (Ni), as required for spintronics applications. We show thickness and phase control, with highly homogeneous wafer-scale monolayers observed under certain conditions, as demonstrated by X-ray photoelectron spectroscopy and Raman spectroscopy mappings. Interestingly, growth appears to be dependent on the substrate selection, with a dramatically increased growth rate on Ni substrates. We show that this 2D…
Membrane potential of single asymmetric nanopores: Divalent cations and salt mixtures
2019
We study the electric potential difference (membrane potential) that arises across a single-pore membrane which separates two aqueous solutions at different salt concentrations. This potential difference is obtained here as the reversal potential of a conical nanopore, defined as the applied voltage needed to obtain a zero current through the membrane. To this end, different monovalent (LiCl, NaCl, KCl, and CsCl) and divalent (CaCl2, MgCl2, and BaCl2) cations are considered over a wide range of concentrations and salt mixtures for the two asymmetric nanostructure directionalities. The experimental data allows discussing fundamental questions on the interaction of the charges fixed to the po…
Use of Silica Based Materials as Modulators of the Lipase Catalyzed Hydrolysis of Fats under Simulated Duodenal Conditions
2020
[EN] The effect of silica materials and their functionalization in the lipase catalyzed fat hydrolysis has been scarcely studied. Fifteen silica materials were prepared and their effect on the fat hydrolysis was measured, under simulated duodenal conditions, using the pH-stat method. The materials are composed of the combination of three supports (Stober massive silica nanoparticles, Stober mesoporous nanoparticles and UVM-7) and four surface functionalizations (methyl, trimethyl, propyl and octyl). In addition, the non-functionalized materials were tested. The functional groups were selected to offer a hydrophobic character to the material improving the interaction with the fat globules an…
NANOTECNOLOGIE PER L'ARCHITETTURA TEMPORANEA
2009
È il tempo a sancire e a governare da sempre il rapporto fra architettura e storia. È il tempo che evidenzia la capacità dell’architettura di essere tramandata ai posteri, di essere eredità e testimonianza, di divenire simbolo caratterizzante un determinato periodo storico. Oggi il concetto di durata trova nuove variabili ed è soggetto a giudizio: la necessità di dare risposte immediate, una modernità sempre più indirizzata al rapido consumo, le esigenze continuamente mutevoli, la disponibilità di nuovi materiali, di componenti e di sistemi costruttivi hanno reso più attuale la realizzazione di manufatti provvisori e mobili. Il progetto si appropria così del tempo e ne controlla il suo stat…