Portail HAL UHA (Université de Haute-Alsace)
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Intensity-energy response function of Al/Cr-K α x-ray photoemission instruments: An inter-laboratory study
No full textInternational audienceThe question of the intensity-energy response of photoemission spectrometers has been approached through a round-robin involving 13 instruments working with low (Al/Mg-K) and high (Cr-K) energy photon sources. An algorithm based on the analysis of inelastic background previously proposed [S. Guilet et al., J. Electron Spectrosc. Relat. Phenom. 285 (2022) 147225)] was intensively tested against calibrated Al/Mg-K instruments and calculated relative sensitivity factors (RSFs) over the 15 core level peaks of coinage metals (Ag, Au, Cu). In both cases, the linear correlation within %, over two orders of magnitude in intensity and for kinetic energies ranging from to , showed the consistency of the approach. All the contributions to RSFs (e.g. non-dipolar terms in the photo-ionization cross section, elastic scattering effects, surface excitations, beam polarization by the monochromator) were critically reviewed and taken into account using the state-of-the-art modellings and databases. Strong variations were evidenced among instruments, regarding not only the response functions, but also the theoretical RSFs due to different measurement geometries. For the Cr-K hard x-ray instruments, the same analysis was performed with a set of different materials (Al, Si, Ge, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ag, W, Au). A % satisfactory agreement against theoretical RSFs over 69 core levels spanning a large kinetic energy range (300–4000 eV) could be achieved with a common response function. Despite limitations that are reviewed, this work opens interesting perspectives for a systematic calibration of photoemission instruments
Supercondensateurs en carbone fonctionnant à 1,8 V basés sur des électrolytes aqueux concentrés : Impacts de la concentration d’électrolyte et propriétés du carbone
No full textInternational audienceAqueous electrolytes with high concentrations of salt are of great interest in increasing the energy density and safety of carbon supercapacitors. Herein, electrolytes based on potassium acetate salt in different concentrations (20–60 wt %) are studied, and a concentration of 40 wt % results in the highest capacitance and rate capability. This behavior is a compromise between the electrolyte ion adsorption, which is small for low concentrations, and the resistance, which is large for high-concentration electrolytes. An increase in the voltage window of 1.8 V is achieved, which significantly improves the capacitance to 162 F g–1 at 0.1 A g–1 and the energy density to 22.9 W h kg–1 at a power density of 45 W kg–1. In addition, the long cycling retention shows the best retention for 1.5 V (104%), which decreases for 1.8 V (72%), however, without significantly increasing the electrode resistance. At 2.0 V, the capacitance drops, and the resistance increases considerably. Subsequently, a series of microporous and mesoporous carbons with different characteristics are investigated with 40 wt % potassium acetate in water at 1.8 V. The development of the specific surface area to 2300 m2 g–1 enables the capacitance to increase (to 182 F g–1 at 0.1 A g–1). At high current density, mesoporosity proved to play a crucial role in enhancing the capacitance retention. Along with the presence of a high oxygen content, the electrolyte diffusion and interactions are favored, which is beneficial for enhanced rate capability. Other properties, such as pore connectivity, material structure, and morphology, are determined to achieve the optimal performance
Guidance on the use of microscopy in the detection of zoosporic parasites of phytoplankton in natural systems and algal biotechnology
No full textThe objective of this methodological paper is to outline a microscopy protocol for detecting and observing fungal zoosporic parasites of phytoplankton in natural environments, with potential applications in algal biotechnology to enhance the success and sustainability of algal cultivation endeavors. The fluorescent dual staining with wheat germ agglutinin (WGA) and Calcofluor White (CFW) showcased during the Training School "Identification and detection of zoosporic parasites" in Neuglobsow (Germany) from 16 th till 18 th of May 2023 and organized and funded by COST Action ParAqua (European Cooperation in Science and Technology) illustrated its ease of implementation and suitability for diverse natural and artificial systems
Plasmon Active Functional Coatings with Hybrid Bimetallic Nanoparticles@Polymers by a Single Step Photoinduced Approach
No full textInternational audienceThis study presents a direct method for creating bimetallic nanoparticles (Ag/Au BNPs) within a polymerizable host by a UV light process under atmospheric conditions (air, temperature and pressure). This approach offers both simplicity and efficiency by combining the photo-induced reduction of metal precursors (AgNO and KAuCl) and the radical photopolymerisation of a polyethylene glycol diacrylate in a single step. As a result, plasmon active coatings were obtained with three different BNPs in the form of Ag-Au alloy or core-shells (Ag@Au or Au@Ag) confined in the polymer matrix, with an average diameter between 4 and 6 nm respectively. The method requires only 15 to 45 minutes depending on the desired BNPs system that were easily triggered by playing with the redox potentials of the metal pairs and small amounts (200-300 µL) of water or acetonitrile solvents used to dissolve these precursors. This control determines which metal is reduced first to form the core and which follows for the shell, or even both simultaneously for the formation of the alloy system. Moreover, double-layered systems such as Ag@Au@Ag can also be synthesised with this approach. Various advanced characterisation techniques, including real-time UV-Vis spectroscopy, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and transmission electron microscopy (in particular STEM-HAADF imaging and EDS elemental mapping), were used to monitor the synthesis process and identify the formed BNPs system. These new plasmonic materials exhibit unique optical properties depending on the BNPs system, making them promising for multiple applications such as sensing, SERS, optics, catalysis or photocatalyse, and easily scalable for large-scale production
Recent Advances and Current Trends in Transmission Tomographic Diffraction Microscopy
No full textInternational audienceOptical microscopy techniques are among the most used methods in biomedical sample characterization. In their more advanced realization, optical microscopes demonstrate resolution down to the nanometric scale. These methods rely on the use of fluorescent sample labeling in order to break the diffraction limit. However, fluorescent molecules’ phototoxicity or photobleaching is not always compatible with the investigated samples. To overcome this limitation, quantitative phase imaging techniques have been proposed. Among these, holographic imaging has demonstrated its ability to image living microscopic samples without staining. However, for a 3D assessment of samples, tomographic acquisitions are needed. Tomographic Diffraction Microscopy (TDM) combines holographic acquisitions with tomographic reconstructions. Relying on a 3D synthetic aperture process, TDM allows for 3D quantitative measurements of the complex refractive index of the investigated sample. Since its initial proposition by Emil Wolf in 1969, the concept of TDM has found a lot of applications and has become one of the hot topics in biomedical imaging. This review focuses on recent achievements in TDM development. Current trends and perspectives of the technique are also discussed
Présentation et retour d'expériences de la construction d'une « SAE Recherche » à destination des étudiants de BUT 3 du département TC de l'IUT de Colmar (Université de Haute Alsace)
No full textInternational audiencePrésentation et retour d'expériences de la construction d'une « SAE Recherche » à destination des étudiants de BUT 3 du département TC de l'IUT de Colmar (Université de Haute Alsace
Sur les traces de la métallurgie de l'antimoine du district de Brioude-Massiac (Haute-Loire -Cantal)
No full textInternational audienceLes vestiges des exploitations de l’antimoine (XVIIIe siècle-années 1970) dans la région de Brioude-Massiac (Haute-Loire¬–Cantal) sont encore bien visibles. En revanche, les traces de la métallurgie dans cette même région sont beaucoup plus rares : les usines ont été démolies. À l’heure d’un regain d’intérêt pour les « métaux stratégiques », il est intéressant de se pencher sur les différents résidus de cette industrie. Ils peuvent en effet receler des teneurs importantes en antimoine ; leur connaissance pourrait ainsi inspirer d’éventuels travaux de valorisation pour la récupération de cet élément. Enfin, ces objets industriels sont des ressources pédagogiques intéressantes pour l’étude de la minéralogie de haute température et les microstructures associées
Near-infrared photocatalysis with cyanines: synthesis, applications and perspectives
No full textInternational audienceCyanine are organic dyes bearing two Aza-heterocycles linked by a polymethine chain. Excited states, fluorescence, redox activity, and energy transfer are interesting properties which have been used by chemists. Moreover, they are easily accessible and highly tunable. For all these reasons, cyanines are often selected for applications like fluorescent probes, phototherapy and photovoltaic. However, considering cyanine as a photocatalyst is a new field of investigation and has been sparsely reported in the literature. This field of research has been launched on the basis of near-infrared light photocatalysis. With a deeper NIR light penetration, the irradiation is compatible with biological tissues. Due to the longer wavelengths that are involved, the safety of operator can be guaranteed. In this perspective review, the photophysical /redox properties of cyanines are reported as well as preparations and applications in modern synthetic approaches. Finally, recent examples of cyanine based NIR-photocatalysis are discussed including photopolymerization and organic synthesi
Désintermédiation et contre-discours des ONG. Lutter contre la désinformation sur les migrations. Le cas de la Cimade
No full textInternational audienceIn the digital age, the need for the humanitarian world to adapt to new information and communication technologies (NICTs) naturally leads non-governmental organisations (NGOs) to practise what is in reality a form of disintermediation. NGOs produce messages which they disseminate in their digital public spaces to inform the public directly, without the mediation of traditional media. These info-communication practices can be a useful way of gaining visibilitsy and combating misinformation about migration. Taking the case of Cimade, the article examines the construction of the NGO counter-discourse and sheds light on the discursive and argumentative processes employed by activists defending the rights of refugees and migrants, with the aim of countering the hegemonic discourses circulating within the media and political spaces. The article shows that NGOs can play a major role in curating information to combat misinformation about migration. However, they face new challenges, particularly in the context of the information war.À l’ère du numérique, la nécessaire adaptation du monde humanitaire aux nouvelles technologies de l’information et de la communication (NTIC) conduit naturellement les organisations non gouvernementales (ONG) à pratiquer ce qui est en réalité, une forme de désintermédiation. Les ONG produisent des messages qu’elles diffusent au sein de leurs espaces publics numériques pour informer directement les publics, sans la médiation des médias traditionnels. Ces pratiques info-communicationnelles peuvent se révéler pertinentes pour gagner en visibilité et lutter contre la désinformation sur les migrations. En prenant le cas de la Cimade, l’article examine la construction du contre-discours des ONG et permet de mettre en lumière les procédés discursifs et argumentatifs employés par les militants de défense des droits des personnes réfugiées et migrantes, dans l’objectif de contrecarrer les discours hégémoniques circulant au sein des espaces médiatiques et politiques. L’article démontre que les ONG peuvent jouer un rôle majeur dans la curation de l’information pour lutter contre la désinformation sur les migrations. Pour autant, elles doivent faire face à de nouveaux enjeux, notamment dans un contexte de guerre de l’information
Multi-Task Learning for PBFT Optimisation in permissioned Blockchains
No full textInternational audienc