HAL Portal IOGS (nstitut d'Optique Graduate School)
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Advanced 1D heterostructures based on nanotube templates and molecules
No full textInternational audienceRecent advancements in materials science have shed light on the potential of exploring hierarchical assemblies of molecules on surfaces, driven by both fundamental and applicative challenges. This field encompasses diverse areas including molecular storage, drug delivery, catalysis, and nanoscale chemical reactions. In this context, the utilization of nanotube templates (NTs) has emerged as promising platforms for achieving advanced one-dimensional (1D) molecular assemblies. NTs offer cylindrical, crystalline structures with high aspect ratios, capable of hosting molecules both externally and internally (Mol@NT). Furthermore, NTs possess a wide array of available diameters, providing tunability for tailored assembly. This review underscores recent breakthroughs in the field of Mol@NT. The first part focuses on the diverse panorama of structural properties in Mol@NT synthesized in the last decade. The advances in understanding encapsulation, adsorption, and ordering mechanisms are detailed. In a second part, the review highlights the physical interactions and photophysics properties of Mol@NT obtained by the confinement of molecules and nanotubes in the van der Waals distance regime. The last part of the review describes potential applicative fields of these 1D heterostructures, providing specific examples in photovoltaics, luminescent materials, and bio-imaging. A conclusion gathers current challenges and perspectives of the field to foster discussion in related communities
Tailoring the statistics of light emitted from two interacting quantum emitters
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Theoretical investigation of refractive index detection limit in the Surface Plasmon Resonance-triggered switch effect
No full textInternational audienceThe metrological performances of a SPR-based sensor exploiting the plasmon-triggered switch effect are investigated in this article. The switch effect, recently demonstrated, is a lossless energy transfer phenomenon between the 0th and -1st diffracted orders, through SPR excited modes, which only occurs in a deep metallic grating while the incidence angle or the wavelength varies. A differential measurement of diffraction efficiencies of these two propagative diffracted orders and an optimized signal filtering, allows to retrieve the sensing signal at a fixed wavelength or fixed incidence angle. For a deep metallic grating illuminated under TM polarization, such a sensor provides a high sensitivity and a limit of detection lower than 10-7 RIU reaching thus the limits of the best current plasmonic methods. The theoretical sensitivity and measurement uncertainties are rigorously investigated considering digital signal processing in order to provide an optimized signal processing and thus increase the sensitivity and the current Limit of Detection (LOD). Due to its performances and its implementation simplicity, this new SPR based sensor is very promising for the detection and quantification of chemical and biological species both in liquid and gaseous environments
CXCL10-dependent epithelial-vascular cross-talk for endothelial activation following Sars-CoV-2 infection
No full textAbstract The vasculature is heavily impacted by SARS-CoV-2 infection. Conflicting results exist concerningthe mechanisms by which the SARS-CoV-2 virus acts on the vasculature. The presence of the virus within endothelial cells has been reported in patient samples. However, the ACE2 receptor wasnot detected in endothelial cells when analyzed by RNAseq analysis. Thus, how SARS-CoV-2 contributes to vascular inflammation and whether cross-talk between epithelial cells and endothelial cells is involvedare unclear. Therefore, we investigated the interaction between SARS-CoV-2 and the vasculature using 2D and 3D in vitro models, as well asour previously developed 3D vesseloid model. We first determined the suitability of the 3D vesseloid model for our study and then assessed whether SARS-CoV-2 is able to directly infect endothelial cells. In the absence of ACE2 in endothelial cells, no infection was detected. When ACE2 was overexpressed in endothelial cells, low uptake of viral particles by endothelial cells was observed without efficient viral production. We then explored the possibility that an indirect effect of SARS-CoV-2 infection involvesepithelial-endothelial cellcross-talk. After infection of the epithelial cells, a significant inflammatory response was detected in the endothelial cells. Furthermore, we investigated the cytokines possibly implicated and identified CXCL10 as the most highly expressed proinflammatorycytokine and explored its function in this context. Finally, the clinical relevance of our findings was confirmed by evaluating CXCL10 and alternative cytokine dosages in blood samples fromSARS-CoV-2-infected patients, which were validated in silico in an independent patient cohort
Numerical analysis of the mechanisms involved in integrated THz imaging with a NIR femtosecond laser illumination
No full textInternational audienceFemtosecond laser allows the production of THz radiation that is very promising for the imaging of various tissues and, namely, for in vivo cancer detection. Despite numerous very convincing experimental demonstrations, the mechanisms involved in image formation are still under discussion. In this paper, based on modeling, we analyze the major physical processes involved in THz laser interactions with tissues, namely with skin. Particular attention is given to the mechanisms involved in integrated THz imaging with NIR femtosecond laser illumination. An effective medium approach is found to be helpful. The difference in water fraction, pores, and additional nanoparticles and nanorods are shown to play a role in the considered non-invasive optical imaging of skin cancer
Ultra-cold atom quantum tunneling through single and double optical barriers
No full textInternational audienceWe realize textbook experiments on Bose-Einstein condensate tunneling through thin repulsive potential barriers. In particular, we demonstrate atom tunneling though a single optical barrier in the quantum scattering regime where the de Broglie wavelength of the atoms is larger than the barrier width. Such a beam splitter can be used for atom interferometry and we study the case of two barriers creating an atomic Fabry-P\'erot cavity. Technically, the velocity spread of the atoms is reduced due to the use of a 39K Bose-Einstein condensate with no interactions. The potential barriers are created optically and their width is tunable due to the use of a digital micro-mirror device. In addition, our scattering experiments enable in situ characterization of the optical aberrations of the barrier optical system
Multi-task learning for identifying multi-activity situations and application type from network traffic
No full textInternational audienceOptimizing networks to meet user needs has been a long-standing goal for the various key players in the network sector. To this end, a large number of studies have addressed the case of classifying network traffic into a set of activities (e.g., streaming) and applications (e.g., Spotify). Nonetheless, the fastpaced growth of the digital market has favored the advent of new consuming habits such as the simultaneous performance of multiple activities. This concept is referred to as multiactivity situations or media multi-tasking. Conceiving solutions that can cope with these emerging consuming patterns may enable network operators and service providers to better adapt their network management solutions and commercial plans. In this paper, we propose a novel approach that can deal with a challenging scenario comprising both single-activity and multi-activity situations. The proposed approach pre-processes a network trace over a time-window and then determines to which situation type it belongs. Furthermore, it identifies the type of the activities being performed and the applications being used (e.g., chat on Facebook & streaming on Spotify). Our experiments highlighted that our solution is able to achieve a satisfactory level of performance despite the complexity of the scenario that we target. Indeed, our obtained results are comparable to stateof-the-art techniques addressing less challenging scenarios that involve only single-activity situations
Radiation Effects on Graded Index Germanosilicate Multimode Optical Fibers
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A comprehensive performance evaluation of bifacial photovoltaic modules: insights from a year-long experimental study conducted in the Canadian climate
No full textInternational audienceBifacial photovoltaic (PV) modules, capable of capturing solar energy from both sides of the cells, are becoming increasingly popular as their manufacturing costs approach those of traditional monofacial modules. Accurate estimation of their power generation capacity is essential for optimizing their use. This study evaluates a power production model for bifacial PV modules using local irradiance data from Razon+ in Sherbrooke, Canada, and Solcast irradiance data derived from satellite imagery and weather models. The model's performance was assessed throughout the year, with particular attention to the impact of snow coverage during winter. To address computational efficiency, the study evaluated ray tracing and a 2D view factor model, selecting the more time-efficient method. Experimental validation showed that, using local irradiance data, the model achieved Normalized Root Mean Square Errors (NRMSE) of 18.77%, 4.94%, 3.93%, and 6.22% for winter, spring, summer, and fall, respectively. With Solcast data, the NRMSEs were 22.76%, 15.32%, 14.72%, and 17.78% for the corresponding seasons. While the model performed satisfactorily in spring, summer, and fall, it was less accurate in winter. To enhance winter accuracy, the model incorporated snow coverage, using snow depth as a metric to detect snow on the front surface. This adjustment improved the accuracy by 51.1%
