Portail HAL UHA (Université de Haute-Alsace)
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Par choix ou par défaut. L’essai des minerais au four à moufle, du XVe au XXIe siècle
No full textInternational audienceAssay of ores played several roles in the history of mining production, particularly from the late medieval period onwards. At this time, laboratory technics of analysis were developed. Then, assays were operated on a few grams of ore into a muffle furnace. Thanks to its representativeness and reproducibility, dry ore assaying methods were useful for mining management, ore trade and optimisation of metallurgical processes. Furthermore, it allowed a rigorous control of the production. Muffle furnace assay was improved all along the 16th century, especially by Lazarus Ercker. No real change was done in the process up to the 19th century. It is still used today, yet other methods exist. Wet processes were elaborated between the 17th and the 19th centuries, and mass spectrometry came in the 20th century. But they never totally replaced dry assaying techniques, which was even the first choice until the mid-19th century.L’essai des minerais a joué plusieurs rôles dans l’économie de la production minière, notamment à partir de la fin de la période médiévale. C’est à cette époque qu’ont été développées des techniques d’analyse opérant sur quelques grammes de minerai dans un four à moufle. Représentatif et reproductible, cet essai par voie sèche était utile à la gestion des chantiers miniers, au commerce des minerais, à l’optimisation des procédés métallurgiques tout en permettant le contrôle de la production. Les modes opératoires de l’essai au four à moufle, perfectionnés au cours du xvie siècle notamment par Lazarus Ercker, ont été pratiqués sans grands changements jusqu’au xixe siècle et le sont encore de nos jours. Une concurrence avec d’autres techniques, développées pour la voie humide du xviie au xixe siècle et pour la spectrométrie de masse au xxe siècle, n’a jamais fait disparaître l’essai par voie sèche. Il a même été préféré à tout autre procédé jusqu’au milieu du xixe siècle
Development of polymer-dye hybrids for optical limitation: photopolymerization versus thermal polymerization
No full textInternational audienceHigh-intensity and low-divergence laser beams can cause damage to the human eye, sensors, and photoreceptors. In harsh environments, optical sensors can be damaged by pulsed laser radiation if exposed beyond their capacity. To protect against such threats, passive optical limiting devices are used. These devices are self-activated systems with a low activation threshold, neutral color, and low response time. Methacrylate-based thermosets were synthesized via radical polymerization using a reactive oligomer and a monomer. Two processes were investigated in this study: thermal polymerization, which is solvent-free, allows to collect directly the sample and can take several hours, and 3D printing, which uses photopolymerization to produce samples. This is an innovative method that allows for the production of multiple samples in under 10 minutes. Furthermore, a non-linear dye has been incorporated into the methacrylate matrix. In this study, optical filters with a methacrylate matrix and a 0.01 wt% loading dye are prepared by bulk polymerization and photopolymerization processes. The samples are then characterized to demonstrate the same chemical composition and thermal behavior. Finally, the optical limiting properties of the thermoset polymers at a wavelength of 1064 nm are investigated. The two processes are compared to determine their relevance
Sustainable extraction of phenolic compounds from olive mill wastewater: harnessing the potential of hydrophobic Deep Eutectic Solvents.
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Advertising endorsement and facial based-image self-threat: an exploratory study in cosmetics
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Chemical Method Based on Thermally Activated Free Radical Polymerization to Determine the Temperature in Thermoplasmonics
No full textRelationship between reflectance and degree of polarization in the VNIR-SWIR: A case study on art paintings with polarimetric reflectance imaging spectroscopy
No full textInternational audienceWe study the relationship between reflectance and the degree of linear polarization of radiation that bounces off the surface of an unvarnished oil painting. We design a VNIR-SWIR (400 nm to 2500 nm) polarimetric reflectance imaging spectroscopy setup that deploys unpolarized light and allows us to estimate the Stokes vector at the pixel level. We observe a strong negative correlation between the S 0 component of the Stokes vector (which can be used to represent the reflectance) and the degree of linear polarization in the visible interval (average -0.81), while the correlation is weaker and varying in the infrared range (average -0.50 in the NIR range between 780 and 1500 nm, and average -0.87 in the SWIR range between 1500 and 2500 nm). By tackling the problem with multi-resolution image analysis, we observe a dependence of the correlation on the local complexity of the surface. Indeed, we observe a general trend that strengthens the negative correlation for the effect of artificial flattening provoked by low image resolutions
Optical and photocatalytic properties of sol-gel AuNPs@TiO2 ultrathin film
No full textThe optical and photocatalytic properties of ultrathin TiO2 layers were investigated in order to stress out the effect of nanoscale thickness on the film properties. The method relies on monitoring localized surface plasmon resonance (LSPR) through UV–visible spectroscopy and enhanced Raman spectroscopy (SERS). To achieve this, TiO2 thin films were prepared using the sol–gel method on high density gold nanoparticles arrays (AuNPs). TiO2 anatase phase was obtained by thermal annealing and confirmed by XRD, HRTEM, and SERS. Our results reveal that the thinnest TiO2 layers consist of compact TiO2NPs of small dimensions and lower porosity compared to the thicker TiO2NPs layers. Subsequently, these thin TiO2 layers functionalizing AuNPs were applied in plasmonic photocatalysis, specifically for the N-demethylation of methylene blue in the visible range. When comparing layers with the same thickness (a single deposition layer with layers prepared by stacking various thin layers), the stacked layers demonstrated enhanced photocatalytic activity. This novel, stable form of TiO2 has the potential to open numerous opportunities in the fields of photocatalysis and detection
Bayesian image segmentation under varying blur with triplet Markov random field
No full textInternational audienceIn this paper, we place ourselves in the context of the Bayesian framework for image segmentation in the presence of varying blur. The proposed approach is based on Triplet Markov Random Fields (TMRF). This method takes into account, during segmentation, peculiarities of an image such as noise, blur, and texture. We present an unsupervised TMRF method, which jointly deals with the problem of segmentation, and that of depth estimation in order to process fluorescence microscopy images. In addition to the estimation of the depth maps using the Metropolis-Hasting and the Stochastic Parameter Estimation (SPE) algorithms, we also estimate the model parameters using the SPE algorithm. We compare our TMRF method to other MRF models on simulated images, and to an unsupervised method from the state of art on real fluorescence microscopy images. Our method offers improved results, especially when blur is important
Hydrodenitrogenation of 1, 2, 3, 4‐Tetrahydroquinoline Over CoMoS/Mesostructured TiO 2 Catalysts
No full textInternational audienceHerein, the design of new catalysts obtained by the dispersion of the CoMoS active phase on mesostructured titania having different pore size and kind of porosity (monomodal vs. dual) for hydrodenitrogenation (HDN) of 1, 2, 3, 4‐tetrahydroquinoline (1234THQ) is reported. Obtained results show that with a selectivity around 93%, the hydrogenated pathway is by far the main route for 1234THQ hydrodenitrogenation. It is also demonstrated that the catalytic activities depend on the mesopore diameter: the larger the size of the mesopores is, the higher the HDN activity is. Comparing with the conventional CoMoP/Al2O3 catalyst, a slightly higher activity is obtained for the mesostructured TiO2 ‐based catalyst due to the promoter effect of titania