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Bosisio R.,NEST | Gorini C.,University of Regensburg | Fleury G.,CEA Saclay Nuclear Research Center | Pichard J.-L.,CEA Saclay Nuclear Research Center
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2016

We consider nanowires in the field effect transistor device configuration. Modeling each nanowire as a one dimensional lattice with random site potentials, we study the heat exchanges between the nanowire electrons and the substrate phonons, when electron transport is due to phonon-assisted hops between localized states. Shifting the nanowire conduction band with a metallic gate induces different behaviors. When the Fermi potential is located near the band center, a bias voltage gives rise to small local heat exchanges which fluctuate randomly along the nanowire. When it is located near one of the band edges, the bias voltage yields heat currents which flow mainly from the substrate towards the nanowire near one boundary of the nanowire, and in the opposite direction near the other boundary. This opens interesting perspectives for heat management at submicron scales: arrays of parallel gated nanowires could be used for a field control of phonon emission/absorption. © 2016.

Bosisio R.,NEST | Gorini C.,University of Regensburg | Fleury G.,CEA Saclay Nuclear Research Center | Pichard J.-L.,CEA Saclay Nuclear Research Center
Physical Review Applied | Year: 2015

We study arrays of parallel doped semiconductor nanowires in a temperature range where the electrons propagate through the nanowires by phonon-assisted hops between localized states. By solving the random-resistor-network problem, we compute the thermopower S, the electrical conductance G, and the electronic thermal conductance Ke of the device. We investigate how those quantities depend on the position - which can be tuned with a back gate - of the nanowire impurity band with respect to the equilibrium electrochemical potential. We show that large power factors can be reached near the band edges, when S self-averages to large values while G is small but scales with the number of wires. Calculating the amount of heat exchanged locally between the electrons inside the nanowires and the phonons of the environment, we show that phonons are mainly absorbed near one electrode and emitted near the other when a charge current is driven through the nanowires near their band edges. This phenomenon could be exploited for a field control of the heat exchange between the phonons and the electrons at submicron scales in electronic circuits. It could be also used for cooling hot spots. © 2015 American Physical Society.

Albertazzi L.,TU Eindhoven | Storti B.,Center for Nanotechnology Innovation | Brondi M.,Center for Nanotechnology Innovation | Sato S.S.,Center for Nanotechnology Innovation | And 3 more authors.
Journal of Visualized Experiments | Year: 2013

The development of fluorescent indicators represented a revolution for life sciences. Genetically encoded and synthetic fluorophores with sensing abilities allowed the visualization of biologically relevant species with high spatial and temporal resolution. Synthetic dyes are of particular interest thanks to their high tunability and the wide range of measureable analytes. However, these molecules suffer several limitations related to small molecule behavior (poor solubility, difficulties in targeting, often no ratiometric imaging allowed). In this work we introduce the development of dendrimer-based sensors and present a procedure for pH measurement in vitro, in living cells and in vivo. We choose dendrimers as ideal platform for our sensors for their many desirable properties (monodispersity, tunable properties, multivalency) that made them a widely used scaffold for several biomedical devices. The conjugation of fluorescent pH indicators to the dendrimer scaffold led to an enhancement of their sensing performances. In particular dendrimers exhibit reduced cell leakage, improved intracellular targeting and allow ratiometric measurements. These novel sensors were successfully employed to measure pH in living HeLa cells and in vivo in mouse brain.

Sreekumar A.,NEST | Meena A.,NEST | Shahabudeen S.,NEST
SAE International Journal of Passenger Cars - Electronic and Electrical Systems | Year: 2014

This paper presents an overview of the telematics domain, with specific focus on the Indian Market. Telematics service areas broadly includes V2X (vehicle-to-vehicle and vehicle-to-infrastructure) and safety communications, fleet management and monitoring, vehicle security, diagnostics, emergency and roadside assistance, automatic crash notification, service appointment scheduling, toll collection, vehicle insurance. Navigation, infotainment and in-car communications are also closely related areas. An emerging trend is that V2X telematics may be delivered using smartphones and networks such as 4G. The primary reason is cost advantage in utilizing smartphones as the platform to bring services to vehicles. Smartphone based applications and web portals can be used to enable remote access features. In fact, if Federal Communications Commission (FCC) decides to eventually share the 5.9 GHz DSRC band, telematics may in fact rely much more on standard telecommunications infrastructure. Thus, a good strategy in the near future may be to reduce reliance on DSRC equipment in vehicles and use smartphones and standard 4G and other telecommunication infrastructure to provide useful telematics services, especially for emerging markets such as India. For India, where road and vehicle safety are major issues and opportunities for customized value added services abound, a detailed analysis of the trends in telematics is required. In terms of telematics services, India is significantly behind other BRICS countries such as China and Brazil. This paper presents some insights into technologies and services that are likely to take off in India in the near future. A user survey has been conducted to gauge the market preferences for Telematics services in India. © 2014 SAE International.

Abbandonato G.,NEST | Storti B.,NEST | Signore G.,Center for Nanotechnology Innovation at | Beltram F.,NEST | Bizzarri R.,NEST
Microscopy Research and Technique | Year: 2016

Reversible photoswitching has been proposed as a way to identify molecules that are present in small numbers over a large, non-switching, background. This approach, called optical-lock-in-detection (OLID) requires the deterministic control of the fluorescence of a photochromic emitter through optical modulation between a bright (on) and a dark state (off). OLID yields a high-contrast map where the switching molecules are pinpointed, but the fractional intensities of the emitters are not returned. The present work presents a modified OLID approach (quantitative OLID or qOLID) that yields quantitative information of the switching (fSW) and non-switching (fNS) components. After the validation of the method with a sample dataset and image sequence, we apply qOLID to measurements in cells that transiently express the photochromic protein EYQ1. We show that qOLID is efficient in separating the modulated from the non-modulated signal, the latter deriving from background/autofluorescence or fluorophores emitting in the same spectral region. Finally, we apply qOLID to Förster (Fluorescence) Resonance Energy Transfer (FRET) imaging. We here demonstrate that qOLID is able to highlight the distribution of FRET intensity in a sample by using a photochromic donor and a non-photochromic acceptor. © 2016 Wiley Periodicals, Inc.

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