Portail HAL UHA (Université de Haute-Alsace)
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Rolled-up gastroretentive oral dosages for controlled release of riboflavin and propranolol
No full textInternational audienceWe present a simple approach to make gelatin gastroretentive oral dosages for controlled release of riboflavin and propranolol. The approach is based on rolling-up of thin selfadhesive gelatin films, on which the reservoirs of the drugs are formed by casting. The radial position of the reservoir and, hence, the lag time and the rate of the drugs release are determined by the lateral position of the reservoir on the film before rolling. Gelatin is stabilized against dissolving in the gastric environment by enzymatic cross-linking mediated by transglutaminase (Tgase). The dosages, which have the form of tight scrolls, are stabilized against unrolling by the crosslinking of the consecutive layers. The scrolls swell in the release media, Fasted State Simulated Gastric Fluid (FaSSGF), to the dimensions which make difficult their passage by the human pyloric sphincter, but remain mechanically robust to resist the stomach peristaltic contractions during at least 24 hours, sufficient for the drug release. Eventually the scrolls are degraded by the release media and can be evacuated from the stomach.</div
Evaluation of micro-hologram activation for dynamic display applications
No full textInternational audienceWe explore the implementation of dynamic behavior in holographic displays through the activation of static elementary holograms. This research takes place in an ambitious concept of near-eye display, free of any focusing optical system. We investigate the dynamic addressing of holographic elements with a size of about 27 µm, distributed on centimeter-size samples. We project dynamic images with a resolution of 10 × 10 pixels. This first demonstration validates the ability to activate pixelated holograms with low cross talk, with an SNR of about 26. We project various images and analyze their rendering in an optical scheme consistent with visual behavior, using the integration time of a camera to mimic visual persistence. We demonstrate the image projection in a free space optical set-up using an SLM. This demonstration may pave the way to further potential developments implementing photonic integrated circuits inside the display
Mechano-metabolism of metastatic breast cancer cells in 2D and 3D microenvironments
No full textCells regulate their shape and metabolic activity in response to the mechano-chemical properties of their microenvironment. To elucidate the impact of matrix stiffness and ligand density on the bioenergetics of mesenchymal cells, we developed a nonequilibrium, active chemo-mechanical model that accounts for the mechanical energy of the cell and matrix, chemical energy from ATP hydrolysis, interfacial energy, and mechano-sensitive regulation of stress fiber assembly through signaling. By integrating the kinetics and energetics of these processes, we define the cell "metabolic potential" that, when minimized, provides testable predictions of cell contractility, shape, and ATP consumption. Specifically, we show that the morphology of MDA-MB-231 breast cancer cells in 3D collagen changes from spherical to elongated to spherical with increasing matrix stiffness, which is consistent with experimental observations. On 2D hydrogels, our model predicts a hemispherical-to-spindle-to-disc shape transition with increasing gel stiffness. In both cases, we show that these shape transitions emerge from competition between the energy of ATP hydrolysis associated with increased contractility that drives cell elongation and the interfacial energy that favors a rounded shape. Furthermore, our model can predict how increased energy demand in stiffer microenvironments is met by AMPK activation, which is confirmed experimentally in both 2D and 3D microenvironments and found to correlate with the upregulation of mitochondrial potential, glucose uptake, and ATP levels, as well as provide estimates of changes in intracellular adenosine nucleotide concentrations with changing environmental stiffness. Overall, we present a framework for relating adherent cell energy levels and contractility through biochemical regulation of underlying physical processes
Towards electrochemical regeneration of redox photocatalysts? The example of the tris(2,2′-bipyridine)ruthenium(II)/methylviologen system
No full textInternational audienceThe regeneration of redox photocatalysts usually requires the use of sacrificial reagents that are added to the medium in stoichiometric amounts, either as an electron donor or as an electron acceptor, to act as an electron relay to the photocatalyst to ensure its effective regeneration. In the present work, we consider the possibility of direct electrochemical regeneration of the catalyst using a model system made of tris(2,2′-bipyridine)ruthenium (II) ([Ru(bpy) 3 ] 2+ ) as photosensitizer and methylviologen (MV 2+ ) as quenching substrate. Based on hydrodynamic amperometry experiments, we demonstrate that this can indeed be possible provided that appropriate potential values are applied to ensure the electrochemical reduction of [Ru(bpy) 3 ] 3+ back to [Ru(bpy) 3 ] 2+ while avoiding interfering processes arising from electron transfer reactions involving the quencher and/or the products/intermediates generated in the course of the photocatalytic event. Furthermore, using EDTA as a sacrificial electron donor, we show that photocurrents can also be exploited for regenerating the quenching substrate by reduction of the reaction product MV•+ (back into MV 2+ ).</div
De l’introspection à la prospection : dynamique collective d’une trajectoire entrepreneuriale d’un tiers-lieu Culturel. Cas de La Friche la Belle de Mai,
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Novel High-Performance Glyoxylate Derivative-based Photoinitiators for Free Radical Photopolymerization and 3D Printing with Visible LED
No full textInternational audienceInvestigations concerning the glyoxylate moiety as a photocleavable functional group for visible light photoinitiators, particularly in the initiation of free radical photopolymerization remain limited. This study introduces nine innovative carbazole‐based ethyl glyoxylate derivatives (CEGs), which are synthesized and found to exhibit excellent photoinitiation abilities as monocomponent photoinitiating systems. Notably, these structures demonstrate robust absorption in the near‐UV/visible range, surpassing the commercial photoinitiators. Moreover, the newly developed glyoxylate derivatives show higher acrylate function conversions compared to a benchmark photoinitiator (MBF) in free radical photopolymerization. Elucidation of the photoinitiation mechanism of CEGs is achieved through a comprehensive analysis involving the decarboxylation reaction and electron spin resonance spin trapping. Furthermore, their practical utility is confirmed during direct laser writing and 3D printing processes, enabling the successful fabrication of 3D printed objects. This study introduces pioneering concepts and effective strategies in the molecular design of novel photoinitiators, showcasing their potential for highly advantageous applications in 3D printing
Comparative analysis of optical and numerical models for reflectance and color prediction of monolithic dental resin composites with varying thicknesses
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Empowering Energy Consumption Forecasting in Smart Buildings: Towards a Hybrid Loss Function
No full textInternational audienceEnergy consumption forecasting is of paramount importance in achieving energy conservation goals. While numerous approaches have been developed to optimize building energy usage, predictive analytics stands out as a cornerstone tool for informed decision-making. Deep learning models have gained popularity for forecasting energy consumption in smart buildings. These models leverage a variety of techniques, including loss functions, activation functions, and optimizers, to enhance training effectiveness. However, the commonly used Mean Squared Error (MSE) as a loss function has a notable drawback as it treats overestimations and underestimations equally. In this study, we propose a novel Hybrid Loss Function (HLF) tailored to address this limitation. The HLF penalizes the model more for underestimating energy consumption during abnormal seasons while maintaining its ability to accurately predict actual consumption, particularly under normal operating conditions. Through extensive simulations, our findings demonstrate that our proposed approach outperforms existing methods in the literature, providing exceptionally accurate and robust forecasts of energy consumption
Sunlight-driven photoinitiating systems for photopolymerization and application in direct laser writing
No full textInternational audienceCurrently, there are only a few industrial and academic works focused on photopolymerization conducted under natural light. To address this challenge, six new dyes are synthesized as photosensitizers and combined with additives (an amine and an iodonium salt) to create three-component photoinitiation systems. These systems can efficiently initiate both the free radical polymerization (FRP) of an acrylate monomer and the cationic polymerization (CP) of an epoxy monomer. Remarkably, the FRP process, facilitated by these systems under natural sunlight, required only a low loading of dyes (0.1 wt% relative to the monomer), and the conversion obtained with dye-B1 as the photosensitizer can reach 90% within 5 minutes. It highlights the viability of natural sunlight as an efficient light source for polymerization processes. More interestingly, dye-B1 can effectively initiate metal-free CP of an epoxy monomer. The chemical mechanism underlying photopolymerization is comprehensively investigated through a combination of theoretical calculations, photolysis experiments, fluorescence quenching experiments, cyclic voltammetry (CV), and electron spin resonance spin trapping (ESR-ST) experiments. Leveraging the exceptional photoinitiation ability of dye-B1, the corresponding three-component photoinitiating system is applied to 3D printing, achieving high-precision 3D patterns via direct laser writing (DLW)