Paul Pascal Research Center

The conformational, (chir)optical and aromatic properties of singly and triply twisted Möbius-shaped cyclotris[5]helicenes are scrutinized.

This systematic review on novel 3D technologies aims to discuss the current evidence on the usefulness of 3D printing, virtual reality (VR) and augmented reality (AR) simulators in the education and training of young urologists for kidney cancer surgery, highlighting the modalities employed, their educational impact, and areas for future development. We performed a comprehensive literature search limited to the last 10 years across PubMed and Embase libraries, identifying studies evaluating the use of 3D technologies as educational tools in urologist training for kidney cancer surgery. The review followed PRISMA guidelines, and two reviewers independently screened eligible studies. We extracted data on study designs and on urologists' education outcomes, through different subcategories. Seventeen studies were included, mostly small-scale validation or descriptive investigations. Twelve investigated 3D-printed models and five VR/AR platforms. Simulations focused on laparoscopic and robot-assisted partial nephrectomy, often using patient-specific models for rehearsal and skill development. Training outcomes included improved spatial anatomy understanding, increased technical performance, greater procedural confidence, and enhanced familiarity with complex surgical steps. However, considerable heterogeneity in methodology and limited sample sizes across studies underscore the need for standardized evaluation of these educational tools. 3D technologies, including 3D-printed models and VR/AR platforms, show promise in enhancing surgical training for renal cancer by improving anatomical understanding and procedural skills. These technologies demonstrate good precision and can help assess trainee surgical skill. However, evidence remains limited, and further research is needed to validate their effectiveness, cost-efficiency, and integration into standardized urological training curricula.

The development of implantable glucose sensors is of significant interest in the management of diabetes. This work focuses on developing an implantable, biocompatible nanoporous gold electrode prototype based on Kapton® for the subcutaneous detection of glucose. The electrodes were first modified with a layer containing glucose oxidase and Os(2,2'-bipyridine)2Cl·PVI (Os(bpy)2Cl PVI). An additional polymeric layer containing poly(2-methacryloyloxyethyl phosphorylcholine-co-glycidyl methacrylate) was then added to reduce biofouling and foreign body reaction effects. The modified electrode had a VMAX of 211±13μAcm-2 and a KMapp of 6.1±0.8mM in pseudo physiological conditions, with a linear detection range from 1 to 4mM and a sensitivity of 28.6±2.1μAcm-2mM-1. In artificial plasma, the response of the sensor was saturated at 3mM, with a VMAX of 113±10μAcm-2 and a KMapp of 2.1±0.4mM with a linear detection range from 1 to 2.5mM and a sensitivity of 14.6±3.3μAcm-2mM-1. Mechanical stress testing demonstrated that there was a 40% reduction of the redox polymer coverage after 320 deformation events, however the catalytic activity was still detectable after 160 events. Minimal cytotoxicity effects of the electrodes were observed. When subcutaneously implanted the electrodes showed fairly good mechanical stability after one week and detachment of the metallic layer on some electrodes after 21days, probably due to electrode bending. A limited foreign body reaction was observed. These results indicated that the electrodes could be implanted for a period of up to 1week.

Abstract Metamaterial research has sought to create nanostructures with strong directional optical scattering to control light propagation at the nanoscale. Core–shell architectures comprised of both resonant cores and resonant shells are suggested as candidate particles in which the spectral overlap of the electric and magnetic dipoles is controlled to create strong directional scattering. In this study, Au‐decorated Si core–shell (Si@Au) particles are presented, studying the role of the architecture (particulate, discontinuous shells vs continuous) and dimensions of the shell. The core–shell particles are synthesized by first creating Si particles, through the thermal disproportionation of hydrogen silsesquioxane (HSQ), which are then decorated with ≈4 nm diameter Au nanoparticles. The resonant behavior of the core–shell particles is characterized using electron energy‐loss spectroscopy mapping and optical single‐particle scatter spectroscopy. These observations are supported by T‐matrix simulations and Mie‐theory calculations of the scattering spectra, which show that, compared to Si, Si@Au particles demonstrate a dampened magnetic dipole resonance for smaller Si core diameters (100–130 nm) and an enhanced magnetic dipole resonance for larger Si core sizes (150–200 nm). The study indicates that the previously reported hybridized modes do not exist in particulate Au shells around a Si core and can only exist in continuous plasmonic shells. Thus, it is shown here how important it is to be as precise as possible regarding the nanomaterial architecture used in simulations. No configuration of Si@Au core–shell particles with a particulate shell could be found that strongly enhanced directional scattering, and a continuous shell may do so only modestly. However, the simulations show that the synthesis of thin, continuous Ag shells might represent an alternative route towards achieving good directional scattering properties.

Recent studies on semi-dilute Calf-Thymus DNA (CT-DNA) solutions have revealed the presence of birefringence and small-scale textures influenced by shear and ionic strength. In this study, we investigate these phenomena on the same solutions to elucidate the underlying shear-induced supramolecular organization and relaxation dynamics using rheo-birefringence, rheology, and rheo-SAXS (small-angle X-ray scattering). Static SAXS confirmed concentration-dependent inter-chain correlations in the 15–25 nm range, while rheology revealed a slipping yield-stress behavior. Oscillatory strain sweep and steady state rheo-birefringence experiments correlated the appearance of textures with the onset of flow and a stress plateau observed over a shear rate range from approximately 1 to 1000 s−1. Transient rheo-birefringence and rheo-SAXS revealed two distinct relaxation mechanisms on well-separated time scales: a fast process lasting a few seconds, inversely proportional to the shear rate, consistent with the orientational relaxation of DNA segments on a ~20 nm scale; and a slower relaxation over tens of seconds, independent of the shear rate, associated with the disappearance of textures, and attributed to a diffusive process. These findings provide significant insights into the mechanisms governing DNA organization and dynamics in semi-dilute solutions under flow and highlight the need for temporally resolved start-up rheo-SAXS and rheo-birefringence measurements, as well as theoretical models describing these processes across various spatial and temporal scales.

The Purcell effect can be used in plasmonic multipod structures to enhance the spontaneous emission of magnetic dipole transitions, which are notoriously weak in nature, while inhibiting the emission of the electric dipole transition. Here, the optical emission from a magnetic dipole transition in a dielectric particle surrounded by metallic satellites, positioned so as to be formal solutions to the Thomson problem, are optimized. Quasi-normal modes (QNMs) are employed for the analysis, offering a significant advantage over traditional real-frequency approaches in reducing a vast parameter space and providing more physical insight. We demonstrate that highly symmetrical N-pods, which can currently be fabricated, are excellent candidates for achieving a large, orientation- and volume-independent magnetic Purcell factor with minimal Ohmic losses. Additionally, we successfully suppress the electric dipole transition, obtaining a magnetic branching ratio exceeding 95% for nearly all N-pod particles. For particles exhibiting a high degree of symmetry, radiated magnetic Purcell factors in excess of 180 are predicted after optimization of the core and satellite radii.

Trinaphthyl-triazines exhibiting persistent room temperature hexagonal columnar mesomorphism with spontaneous homeotropic alignment, large S 0 –S 1 /T 1 energy gaps, and aggregate-based fluorescence.

Abstract We study theoretically the emission and lasing properties of a single nanoshell spaser nanoparticle with an active core and a plasmonic metal shell. Using time-dependent equations for the gain medium and metal, we calculate the lasing threshold through an instability analysis. Below threshold, the nanoshell acts as an optical amplifier when excited by an external probe field, while above threshold, it enters a regime of autonomous lasing. At the gain threshold, the lasing starts at one frequency, typically a plasmon resonance of the nanoparticle. With increasing gain, the emission then broadens to additional frequencies. This result contrasts with previous findings reporting only a single emission wavelength above threshold. We also compute the full spectrum and linewidth of the nanolaser, revealing strong frequency shifts and an asymmetrical lineshape. Finally, we demonstrate that the emission line can be tuned across the visible spectrum by modifying the aspect ratio of the nanoshell.

A new paramagnetic ligand, 4-(2'-4-(2''-furyl)-pyrimidyl)-1,2,3,5-dithiadiazolyl (furylpymDTDA) and three transition metal coordination complexes, M(hfac)2(furylpymDTDA) M=Mn, Co, Ni; hfac=1,1,1,5,5,5-hexafluoroacetylacetonato-), are reported. The solid-state structures are influenced by the geometry of the coordination sphere of the M(II) centers: trigonal (Mn) vs. octahedral (Co and Ni). While the hs-Mn(II) complex exhibits pairwise multi-centre 2-electron bonds (i. e., pancake bonds) between the planar π radical DTDA moieties, the hs-Co(II) and Ni(II) complexes crystallize with close contacts between coordinated furylpymDTDA radical ligands that define linear 1D arrays of molecular units. The magnetic data for the hs-Co(II) and Ni(II) complexes indicate ferromagnetic (FM) interactions between molecular units, apparently mediated by radical-radical contacts along the supramolecular chains. Computational analysis suggests proximity between regions of large α- and β-spin density on neighbouring molecular sites enabling FM exchange, in accordance with the McConnell I mechanism. The magnetic data for the Ni(II) complex are consistent with a Heisenberg spin chain, whereas the hs-Co(II) complex exhibits Ising-like spin chain behaviour and a magnetic phase transition to an FM ordered state at 4.6 K.

Abstract The water bottle flip experiment is a recreational, non-conventional illustration of the conservation of angular momentum. When a bottle partially filled with water is thrown in a rotational motion, water redistributes throughout the bottle, resulting in an increase of moment of inertia and thus a decrease in angular velocity, which increases the probability of it falling upright on a table as compared with a bottle filled with ice. The investigation of this phenomenom is accessible to undergraduate students and should allow them to gain better understanding of combined translational and rotational motions in classical mechanics. We report a series of detailed experiments that are quantitatively compared with numerical calculations based on a simple theoretical framework in which the water volume is decomposed into thin slices of a rigid body that are subjected to fictitious forces in the non-inertial frame of the spinning bottle. This model also allows us to capture and predict other experimental configurations. Finally, we discuss additional counter-intuitive effects that contribute to bottle stabilization on landing.