Hydrophilic or hydrophobic coating of whey protein aerogels obtained by supercritical-CO2-drying: Effect on physical properties, moisture adsorption and interaction with water and oil in food systems

Aerogel monoliths, prepared by water-to-ethanol substitution and supercritical-CO2-drying of whey protein hydrogels, were dip-coated with hydrophilic (alginate, AL; agar, AG) or hydrophobic (ethylcellulose, EC) polymers. AL coating induced aerogel collapse, due to solvent absorption. AG and EC rapidly set onto aerogel surface, forming layers of 65 and 100 μm thickness, respectively. While AG-coating induced 20% volume shrinkage, 25% apparent density increase and 75% firmness increase, EC-coating maintained the original aerogel structure. Upon exposure to 100% equilibrium relative humidity, aerogels showed moisture uptake in the order AG-coated>uncoated>EC-coated. When immersed in water or oil, the AG-coated aerogel showed an uptake respectively 40 and 60% lower than the uncoated control. The oil barrier capacity of AG-coated aerogel was also demonstrated in a lipid food system (stearin-oil mixture). Although not reducing oil uptake, EC-coating reduced water uptake by 30% and its water barrier properties were demonstrated upon immersion in an aqueous food system (water-flour batter). Industrial relevance: The obtained results indicate tailored coating as a feasible strategy to enhance aerogel functionality in food. This would open further possibilities, including the use of aerogels as smart food ingredients able to modulate aroma and bioactive delivery both in the food product and during digestion. These findings are thus important in supporting the industrial development of aerogel-based ingredients with customized functionalities

Surface composition of BaTiO3/SrTiO3(001) films grown by atomic oxygen plasma assisted molecular beam epitaxy

We have investigated the growth of BaTiO3 thin films deposited on pure and 1% Nb-doped SrTiO3(001) single crystals using atomic oxygen assisted molecular beam epitaxy (AO-MBE) and dedicated Ba and Ti Knudsen cells. Thicknesses up to 30 nm were investigated for various layer compositions. We demonstrate 2D growth and epitaxial single crystalline BaTiO3 layers up to 10 nm before additional 3D features appear; lattice parameter relaxation occurs during the first few nanometers and is completed at {\guillemotright}10 nm. The presence of a Ba oxide rich top layer that probably favors 2D growth is evidenced for well crystallized layers. We show that the Ba oxide rich top layer can be removed by chemical etching. The present work stresses the importance of stoichiometry and surface composition of BaTiO3 layers, especially in view of their integration in devices.Comment: In press in J. Appl. Phy

Study of the Effect of L-PBF Technique Temporal Evolution on Microstructure, Surface Texture, and Fatigue Performance of Ti gr. 23 Alloy

Titanium alloys are widely used in various technological fields due to their excellent performance. Since the early stages of the 3D printing concept, these alloys have been intensively used as materials for these processes. In this work, the evolution of the performance of the 3D printing process has been studied by analysing the microstructure and the mechanical properties, fatigue and tensile, of the Ti gr. 23 alloy produced by two different models of Concept Laser M2 Cusing machines (an old model and a more recent one). The process parameters recommended by the manufacturer were adopted for each machine. Both microstructural and surface texture characterisations were carried out to better correlate the differences with the production process technique. For the same purpose, tensile tests and microhardness profiles were obtained, while the dynamic mechanical properties were evaluated by means of fatigue tests aimed at determining the fatigue limit of the material using a staircase approach. The mechanical tests were carried out on specimens with three different orientations with respect to the building platform, using two different SLM techniques. The fatigue behaviour was then analysed by evaluating the fracture surfaces and, in particular, the crack nucleation sites. By comparing the calculated fatigue values with the results of local fatigue calculations, an estimate of the residual stresses near the crack nucleation site was obtained. The results showed that the specimens produced on a newer machine had lower roughness (about 10%), slightly higher ductility, and a higher fatigue limit (10–20 MPa) compared to the specimens produced with the same material but on older equipment

Radiation Induced Defects in 8T-CMOS Global Shutter Image Sensor for Space Application

International audienceWe propose to identify the displacement damage defects induced by proton and carbon irradiations in a commercial off-the-shelf pinned photodiode (PPD) 8T-CMOS image sensors (CISs) dedicated to space application operating in global shutter mode. This paper aims to provide a better understanding of defects creation in a specific space image sensor. Therefore, it leads to comparable results to those we could find during the mission. The study focuses on bulk defects located in the PPD depleted region which represents the main dark current contribution in PPD CIS. Four sensors have been irradiated with carbon ions and protons at different energies and fluencies. Using both the dark current spectroscopy and the random telegraph signal (RTS) analysis, we investigate defects behavior for different isochronal annealing temperatures. By combining these results, we make the connection between two complementary phenomena and bring out the prevalence of divacancies-based defects in term of dark current contribution

Crystallographic structure of ultrathin Fe films on Cu(100)

We report bcc-like crystal structures in 2-4 ML Fe films grown on fcc Cu(100) using scanning tunneling microscopy. The local bcc structure provides a straightforward explanation for their frequently reported outstanding magnetic properties, i.e., ferromagnetic ordering in all layers with a Curie temperature above 300 K. The non-pseudomorphic structure, which becomes pseudomorphic above 4 ML film thickness is unexpected in terms of conventional rules of thin film growth and stresses the importance of finite thickness effects in ferromagnetic ultrathin films.Comment: 4 pages, 3 figures, RevTeX/LaTeX2.0

The use of ALD and PVD coatings as defect sealants to increase the corrosion resistance of thermal spray coatings

Thermal spray coatings are widely used to improve the surface properties of materials, in particular the wear and oxidation resistance. Nevertheless, the corrosion resistance is slightly increased due to the fact that this type of coatings present some internal defects (pores, cracks) that allow the corrosive media to penetrate up to the substrate, that undergoes to corrosion degradation. The amount of these defects is strongly influenced by both the deposition technique and the material deposited. The aim of this work is to seal the internal porosities of the thermal spray coatings by the use of both PVD and ALD coatings or the combination of the two. The thermal spray coating analysed in this work is a pure alumina coating, deposited by Air Plasma Spray (APS) technique, that has been sealed with CrN coating, deposited by PVD (Physical Vapour Deposition) technique, and/or TiO2 coatings, deposited by ALD (Atomic Layer Deposition). The substrate used is a common medium C steel. The samples were then characterized in order to determine the microstructure (SEM+EDXS, light microscope) and the chemical composition (Rf-GDOES elemental profiling), that is important to determine the depth of penetration of the PVD and/or ALD coating inside the thermal spray deposit. Afterwards, a detailed electrochemical characterization in 3,5wt% NaCl aqueous solution was performed to verify the efficiency of the sealant treatment. In detail, a monitor in function of the time of the OCP potential was performed up to 24h of immersion time. In addition, potentiodynamic tests were performed using a 3 electrode electrochemical cell (CE: Pt wire, RE: Ag/AgCl). The same tests were then performed on the same samples that present an artificial defect produced by Rf-GDOES. The main goal of these tests is to determine the maximum depth of a defect that can allow the corrosive media to penetrate the thermal spray coating. Preliminary results showed that the use of PVD and ALD coatings as sealants can reduce the permeation of the corrosive media on the substrate

The Use of Thin Films as Defect Sealants to Increase the Corrosion Resistance of Thermal Spray Coatings

Thermal spray-coated components are widely used as wear-resistant coatings in many applications. However, these coatings have high levels of discontinuities that affect the corrosion resistance of the coated system. To reduce this problem, these coatings are usually sealed with liquid sealants (metals, organic or inorganic). The aim of this work is to seal the surface discontinuities of thermal-sprayed coatings using PVD and/or ALD coatings. To this end, CrN (arc deposition PVD) and TiO2 (ALD) coatings were deposited on thermal-sprayed alumina coatings. The samples produced were then analysed in both cross-sectional and planar views to detect the possible permeation of the thin film coatings into the thermal spray defects. Rf-GDOES measurements were performed to detect the very thin ALD deposit on the surface. The corrosion resistance of the sealed coatings was verified with immersion tests, wherein the OCP was monitored for 24 h, and potentiodynamic tests were performed after 15 min and 24 h immersions. The results showed that the thin films were not able to block the permeation of corrosive media, but they could reduce the permeation of corrosive media with a beneficial behaviour on corrosion resistance

A Comparative Analysis of the Determinants of Executive Compensation between Canadian and U.S. Firms

Partout en Amérique du Nord, la rémunération des dirigeants de sociétés ouvertes fait de plus en plus l'objet d'un examen minutieux. Cette préoccupation se reflète dans la presse populaire {Globe and Mail, 10 avril 1993 ; Time, 9 janvier 1992) et dans les multiples revues de littérature sur la rémunération des dirigeants (Gomez-Mejia et Welbourne 1989 ; Lambert et Larcker 1991 ; Milkovich et Rabin 1991). Toutefois, la quasi-totalité de la recherche a été réalisée dans un contexte américain. En effet, alors qu'aux États-Unis la Securities and Exchange Commission (SEC) exige que les sociétés ouvertes divulguent la rémunération de leurs cinq dirigeants les mieux payés, les réglementations canadiennes n'obligeaient jusqu'à récemment les sociétés ouvertes à ne divulguer que la somme reçue par leurs dirigeants en tant que groupe.La présente étude vise à combler partiellement ce vide en utilisant les seules données fiables sur la rémunération des dirigeants canadiens, lesquelles sont publiées par des sociétés dont le siège social est au Canada et dont les actions sont négociées sur un marché boursier américain. Ces sociétés sont sujettes à la réglementation américaine de divulgation de la rémunération des dirigeants. La rémunération des dirigeants de ces sociétés canadiennes est d'abord analysée quant à l'étendue des quatre liens suivants (1) la relation entre la taille de l'organisation et la rémunération des dirigeants, (2) celui entre la performance organisationnelle et la rémunération des dirigeants, (3) l'effet direct du contrôle financier de la firme sur la rémunération des dirigeants et, (4) l'effet modérateur du contrôle financier d'une firme sur la relation entre la performance organisationnelle et la rémunération des dirigeants. Par la suite, la rémunération des dirigeants de ces sociétés canadiennes est comparée à celle des dirigeants de sociétés américaines similaires (taille, secteur) quant à l'étendue des quatre liens susmentionnés. L'ampleur des liens est inférée des coefficients obtenus d'analyses de régressions des moindres carrés.Les résultats obtenus indiquent que la taille d'une organisation est reliée positivement à la rémunération des dirigeants des sociétés canadiennes, et de façon plus étroite que pour les dirigeants de sociétés américaines. Les résultats sont cohérents avec ceux obtenus par les études antérieures tant britanniques qu'américaines. Les résultats de l'étude indiquent également que la performance organisationnelle, mesurée par le rendement de l'avoir des actionnaires, influence positivement la rémunération des dirigeants de sociétés canadiennes. Cette relation est toutefois plus forte dans le cas des dirigeants de sociétés américaines. Il ressort également de l'étude que la présence d'actionnaires importants dans une société (contrôle restreint) réduit le niveau de rémunération de ses dirigeants comparativement aux sociétés sans bloc de contrôle (propriété dispersée). Cet effet est plus marqué pour les sociétés américaines. La relation entre la performance organisationnelle et la rémunération des dirigeants de sociétés canadiennes et américaines est toutefois modifiée par l'introduction du contrôle financier comme variable modératrice. En effet, la performance organisationnelle — estimée à partir d'un indice de marché — a un effet positif sur la rémunération des dirigeants de sociétés canadiennes à propriété dispersée mais non sur la rémunération des dirigeants de sociétés canadiennes à contrôle restreint. Par contre, pour les dirigeants de sociétés américaines, la relation entre la performance organisationnelle — estimée par un indice de marché — et la rémunération des dirigeants est positive uniquement pour les sociétés à contrôle restreint mais non pour les sociétés à propriété dispersée. Les résultats obtenus pour les firmes américaines, mais non pour les firmes canadiennes, sont cohérents avec l'interprétation de la théorie des agences proposée par Tosi et Gomez-Mejia (1989). Selon ces auteurs, l'existence d'un bloc de contrôle dans l'actionnariat d'une firme devrait amener l'établissement d'un lien plus étroit entre la performance organisationnelle et la rémunération des dirigeants car les actionnaires ont la capacité d'imposer une formule de rémunération contingente à la performance.This study attempts to identify determinants of executive compensation in Canada while comparing how they differ between Canada and the United States. Results suggest that firm size, firm performance, and firm ownership structure all determine executive compensation in Canada. However, several differences between the determinants of executive compensation in Canada and the U.S. are identified

What is a fish? The life and legend of David L.G. Noakes

David Lloyd George Noakes (1942–2020) is best known for his insatiable curiosity, his quick wit and dry sense of humor, his scientific contributions to the field of animal behaviour, and his ability to form and maintain long-lasting connections. His research interests were vast but remained grounded in early life history, behaviour, social behaviour, the evolution of behaviour, behavioural genetics, and evolutionary ecology. David had a remarkable ability to establish and maintain strong connections within the international academic community. David was also internationally recognized for his numerous contributions as a scientific editor, promoting accessibility to the international community that he served. We memorialize David’s legacy in this tribute article, ensuring that his accomplishments and the momentous impact he had on the scientific community are not soon forgotten