Kinetics of photoinduced matter transport driven by intensity and polarization in thin films containing azobenzene

We investigate the kinetics of photoinduced deformation phenomena in azobenzene-containing thin solid films. We show that a light intensity pattern and a light polarization pattern produce two distinct material transport processes whose direction and kinetics can be independently controlled. The kinetics of the intensity-driven deformation scales with the incoming light power while the kinetics of the polarization-driven mass transport scales with the amplitude of the electromagnetic field pattern. We conclude that these two processes are fully independent one from the other and originate from two different microscopic mechanisms

Photonic crystal-driven spectral concentration for upconversion photovoltaics

International audienceThe main challenge for applying upconversion (UC) to silicon photovoltaics is the limited amount of solar energy harvested directly via erbium-based upconverter materials (24.5 W m(-2)). This could be increased up to 87.7 W m(-2) via spectral concentration. Due to the nonlinear behavior of UC, this could increase the best UC emission by a factor 13. In this paper, the combined use of quantum dots (QDs)for luminescent down-shiftingand photonic crystals (PCs)for reshaping the emissionto achieve spectral concentration is shown. This implies dealing with the coupling of colloidal QDs and PC at the high-density regime, where the modes are shifted and broadened. In the first fabricated all-optical devices, the spectral concentration rises by 67%, the QD emission that matches the absorption of erbium-based upconverters increases by 158%, and the vertical emission experiences a 680% enhancement. Remarkably, the PC redshifts the overall emission of the QDs, which could be used to develop systems with low reabsorption losses. In light of this, spectral concentration should be regarded as one of the main strategies for UC photovoltaics

Modeling electrodialysis and a photochemical process for their integration in saline wastewater treatment.

Oxidation processes can be used to treat industrial wastewater containing non-biodegradable organic compounds. However, the presence of dissolved salts may inhibit or retard the treatment process. In this study, wastewater desalination by electrodialysis (ED) associated with an advanced oxidation process (photo-Fenton) was applied to an aqueous NaCl solution containing phenol. The influence of process variables on the demineralization factor was investigated for ED in pilot scale and a correlation was obtained between the phenol, salt and water fluxes with the driving force. The oxidation process was investigated in a laboratory batch reactor and a model based on artificial neural networks was developed by fitting the experimental data describing the reaction rate as a function of the input variables. With the experimental parameters of both processes, a dynamic model was developed for ED and a continuous model, using a plug flow reactor approach, for the oxidation process. Finally, the hybrid model simulation could validate different scenarios of the integrated system and can be used for process optimization

Interactions of lipid monolayers with the natural biopolymer hyaluronic acid

AbstractThe interaction of the natural mucopolysaccharide hyaluronic acid with different lipids, present in the natural membranes, was studied at the lipid/water interface using thermodynamic methods and X-ray diffraction. The results show that this biopolymer modifies the properties and the structure of the lipid monolayer. The two-dimensional crystalline lattice and domain structure of the charged octadecylamine monolayer are strongly disturbed by the hyaluronic acid, the monolayer compressibility increases and the monolayer collapse pressure drops down. In addition, the presence of charged lipid interfaces influences the structural organisation of the hyaluronic acid at the membrane/water interfaces. The impacts of these results on the structural organisation at the membrane interface are discussed

Non-thermal emission from star-forming galaxies detected in gamma rays

Star-forming galaxies (SFGs) emit non-thermal radiation from radio to gamma-rays. We aim to investigate the main mechanisms of global CR transport and cooling in SFGs. The way they contribute in shaping the relations between non-thermal luminosities and SFR could shed light onto their nature. We develop a model to compute the CR populations of SFGs, taking into account their production, transport, and cooling. The model is parameterised only through global galaxy properties, and describes the non-thermal emission in both radio and gamma-rays. We focus on the role of diffusive and advective transport by galactic winds, either driven by turbulent or thermal instabilities. We compare model predictions to observations, for which we compile a homogeneous set of luminosities in these radio bands, and update those available in gamma-rays. Our model reproduces reasonably well the observed relations between the gamma-ray or 1.4 GHz radio luminosities and the SFR, assuming a single power-law scaling of the magnetic field with the latter with index beta=0.3, and winds blowing either at Alfvenic speeds or typical starburst wind velocities. Escape of CR is negligible for > 30 Mo/yr. A constant ionisation fraction of the interstellar medium fails to reproduce the 150 MHz radio luminosity throughout the whole SFR range. Our results reinforce the idea that galaxies with high SFR are CR calorimeters, and that the main mechanism driving proton escape is diffusion, whereas electron escape also proceeds via wind advection. They also suggest that these winds should be CR or thermally-driven at low and intermediate SFR, respectively. Our results globally support that magnetohydrodynamic turbulence is responsible for the dependence of the magnetic field strength on the SFR and that the ionisation fraction is strongly disfavoured to be constant throughout the whole SFR range.Comment: Submitted to Astronomy & Astrophysics (on 12/05/2021

A discrimination algorithm inside λ-β-calculus

AbstractA finite set {F1,…,Fn} of λ-terms is said to be discriminable if, given n arbitrary λ-terms X1,…,Xn, there exists a λ-term Δ such that: ΔFi ⩾ Xi for 1 ⩽ i ⩽ n. In the present paper each finite set of normal combinators which are pairwise non α-η-convertible is proved to be discriminable. Moreover a discrimination algorithm is given

3‐D GPR Imaging of Complex Fluvial Stratigraphy at the Boise Hydrogeophysical Research Site

A series of three-dimensional (3-D) ground-penetrating radar (GPR) data sets were acquired over the central wellfield area at the Boise Hydrogeophysical Research Site (BHRS). The survey region is 30 m x 18 m and encompasses 13 wells. The goal of the surveys is to image the complex fluvial (cobble-and-sand) stratigraphy around the wellfield. These images will be used to construct 3-D models of the sedimentary architecture and to help constrain fine-scale models of hydrologic and geophysical parameters at the site. The data sets were acquired using 25 MHz, 50 MHz, 100 MHz and 200 MHz antennas. Depth of penetration ranges from -9.6 m for the 200 MHz data to -22 m for the 25 MHz data. Processing significantly improves the reliability and interpretability of the images. The images suggest that the deposit can be subdivided laterally and vertically into several distinct units or radar architectural elements; these elements are typically separated by erosional bounding surfaces. Horizontal bedding, cross-bedding and channel structures are clearly evident in the 100 MHz and 200 MHz data, and a clay layer that underlies the cobble-and-sand aquifer at -20 m depth is successfully imaged in the 25 MHz and 50 MHz data. The water table, at a depth of l-2 m, is imaged in the 100 MHz and 200 MHz data. Time slices and vertical cuts through the data volumes are used to identify the shape and orientation of the different architectural elements, and to accurately locate important hydrostratigraphic boundaries. These data are being used to construct a 3-D model of the hydrogeologic zonation of the aquifer. Hydrologic and geophysical parameter values associated with each zone will be determined from additional field measurements (e.g., hydraulic tests in wells, crosshole radar and seismic tomography, transient electromagnetics, and well logs). The 3-D GPR surveys provide valuable information about the location, scale and geometry of different stratigraphic units at the BHRS

Narrow Band Imaging and High Definition Television in endoscopic evaluation of upper aero-digestive tract cancer.

Narrow band imaging and high definition television are recent innovations in upper aero-digestive tract endoscopy. Aim of this prospective, non-randomized, unblinded study was to establish the diagnostic advantage of these procedures in the evaluation of squamous cell cancer arising from various upper aero-digestive tract sites. Between April 2007 and January 2010, 444 patients affected by upper aero-digestive tract squamous cell cancer, or previously treated for it, were evaluated by white light and narrow band imaging ± high definition television endoscopy, both in the pre-/intra-operative setting and during follow-up. Tumour resection was performed taking into account narrow band imaging and high definition television information to obtain histopathologic confirmation of their validity. Endoscopic and pathologic data were subsequently matched to obtain sensitivity, specificity, positive, negative predictive values, and accuracy. Overall, 110 (25%) patients showed adjunctive findings by narrow band imaging ± high definition television when compared to standard white light endoscopy. Of these patients, 98 (89%) received histopatological confirmation. The sensitivity, specificity, positive, negative predictive values, and accuracy for white light-high definition television were 41%, 92%, 87%, 82%, and 67%, for narrow band imaging alone 75%, 87%, 87%, 74%, and 80%, and for narrow band imaging-high definition television 97%, 84%, 88%, 96%, and 92%. The highest diagnostic gain was observed in the oral cavity and oropharynx (25%). Narrow band imaging and high definition television were of value in the definition of superficial tumour extension, and in the detection of synchronous lesions in the pre-/intra-operative settings. These technologies also played an important role during post-treatment surveillance for early detection of persistences, recurrences, and metachronous tumours