Time-Resolved Diffusing Wave Spectroscopy for selected photon paths beyond 300 transport mean free paths

This paper is devoted to the theoretical and experimental demonstration of the possibility to perform time-resolved diffusing wave spectroscopy: we successfully registered field fluctuations for selected photon path lengths that can overpass 300 transport mean free paths. Such a performance opens new possibilities for biomedical optics applications.Comment: 12 pages, 3 figure

Un outil de desserte et de désenclavement : le téléphérique

L’étude attentive des téléphériques comme moyens de transport polyvalents est révélatrice des genres de vie des populations en montagne, mais aussi des politiques de développement et des grands chantiers nés après la révolution industrielle. L’invention du câble d’acier en 1834, en Allemagne, amplifie ce phénomène largement sous-estimé, apparu avec l’usage déjà fort ancien de cordes au travers de gorges. Ces téléphériques développés d’abord pour le transport de marchandises, puis celui de personnes, vont rendre d’inestimables services aux populations montagnardes, participant au désenclavement de villages en Suisse (Valais, Uri), partout en Europe, puis au Nouveau Monde ou en Asie. Bois, bidons de lait, fourrage, vendanges, mais aussi charges lourdes, ciment, charbon, minerais divers... La liste longue, voire surprenante, des usages rendus possibles par ces câbles de toutes dimensions n’a d’égale que la souplesse d’adaptation aux reliefs, aux contraintes locales, sous tous les climats

OM-MADE:An open-source program to simulate one-dimensional solute transport in multiple exchanging conduits and storage zones

International audienceOM-MADE (One-dimensional Model for Multiple Advection, Dispersion, and storage in Exchanging zones) is an open-source python code for simulating one-dimensional solute transport in multiple exchanging conduits and storage zones in steady-state flow conditions. It aims at helping the interpretation of multi-peaked skewed breakthrough curves (BTCs) that can be observed in tracer tests conducted in karstic systems. OM-MADE is based on the resolution of classical mass conservation equations. In OM-MADE, all parallel and exchanging flow zones are divided along the direction of flow into reaches, in which all model parameters are kept constant. The total flowrate may be modified through lateral in and outflows. The solute may also be affected by decay processes either in mobile or immobile zones. Each reach is subdivided into discrete segments of equal length. The partial differential equations can be solved using two second order schemes, one based on an operator-split approach, the other on Crank-Nicholson pondered scheme. A verification is performed against analytical solutions, OTIS software [Runkel, 1998], and the dual-advection dispersion equation (DADE) proposed by Field and Leij [2012]. An application to a tracer test carried out in the karstic area of Furfooz (Belgium) is then performed to reproduce the double-peaked positively skewed BTC that has been observed. It constitutes a demonstration of the software capacities in the case of two reaches and three exchanging zones, among which two are mobile ones and one represents a storage zone. It thus permits to verify numerically the consistency of the conceptual interpretation of the observed BTC

Assessment of spray drift potential reduction for hollow-cone nozzles: Part 1. Classification using indirect methods

Spray drift is one of the main pollution sources identified when pesticides are sprayed on crops. In this work, in order to simplify the evaluation of hollow-cone nozzles according to their drift potential reduction, several models commonly used were tested by three indirect methods: phase Doppler particle analyser (PDPA) and two different wind tunnels. The main aim of this study is then to classify for the first time these hollow-cone nozzle models all of them used in tree crop spraying (3D crops). A comparison between these indirect methods to assess their suitability and to provide guidelines for a spray drift classification of hollow-cone nozzles was carried out. The results show that, in general terms, all methods allow hollow-cone nozzle classifications according to their drift potential reduction (DPR) with a similar trend. Among all the parameters determined with the PDPA, the V100 parameter performed best in differentiating the tested nozzles among drift reduction classes. In the wind tunnel, similar values were obtained for both sedimenting and airborne drift depositions. The V100 parameter displayed a high correlation (up to R2 = 0.948) with the drift potential tested with the wind tunnel. It is concluded that in general, the evaluated indirect methods provide equivalent classification results. Additional studies with a greater variety of nozzle types are required to achieve a proposal of harmonized methodology for testing hollow-cone nozzles.This work was partly funded by the Secretaria d'Universitats i Recerca del Departament d'Empresa i Coneixement de la Generalitat de Catalunya, the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF) under Grants 2017 SGR 646, AGL2007-66093-C04-03, AGL2010-22304-04-C03-03, and AGL2013-48297-C2-2-R. The authors also wish to thank Mr. Antonio Checa (Randex Iberica, S.L.) for giving us free Albuz nozzles for the spray tests. Universitat de Lleida is also thanked for Mr. X. Torrent's pre-doctoral fellowship

Time-resolved measurements from speckle interferometry

We present time-resolved measurements by speckle interferometry of the light scattered by a liquid medium. Measurements were performed by use of reflectance geometry and are compared with results obtained in the same conditions with a femtosecond laser and a streak camera. The setup was also tested in vivo on the forearm of a human volunteer to demonstrate the potential utility of such a setup for biomedical applications

Time-resolved diffusing wave spectroscopy applied to dynamic heterogeneity imaging

We report in this paper what is to our knowledge the first observation of a time-resolved diffusing wave spectroscopy signal recorded by transillumination through a thick turbid medium: the DWS signal is measured for a fixed photon transit time, which opens the possibility of improving the spatial resolution. This technique could find biomedical applications, especially in mammography.Comment: 9 pages, 4 figure

Hydrogen storage in carbon nanotubes: Residual metal content and pretreatment temperature

Hydrogen storage in MWNT was enhanced via the catalytic activity of NiMgO. The magnitude of the hydrogen to metal ratio for the MWNT/NiMgO system, combined with temperature programmed adsorption and desorption studies, showed hydrogen spillover from the catalyst to the carbon surface. Metal doping combined with temperature activation studies showed that both nickel and magnesium are active in the catalytic process. The yield, quality, and carbon-metal contact were shown to affect hydrogen uptake. Higher pretreatment temperatures enhanced uptake, for both low- and high-pressure measurements, due to increased carbon-metal contact and activation of the catalyst. At 69 bar (or 1,000 psia), the hydrogen adsorption and desorption of the MWNT/NiMgO system were 3.7% and 3.6%, respectively.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34249/1/690490619_ftp.pd