Synthesis and luminescence properties of Eu3+ -doped silicate nanomaterial

AbstractIn this paper, we introduce a sol-gel process for preparing Y 2Si2O7:Eu3+ nanocrystals. The rare earth compounds were dispersed in the SiO2 colloids and the monodisperse nano-scale composite materials were prepared. The reactant mass fraction and heat treatment temperatures could affect the structures and emission spectrum properties of as-synthesized samples. The samples emit the strong red light upon excitation under the ultraviolet. The main peaks originate from 5D0−7F2 electric dipole transition of Eu3+. With regard to the samples treated at different temperatures, the emission spectra obtained under 266 nm excitation show different shapes of spectra lines and relative intensities, indicating that the Eu3+ ions have been located in different local environments

Interpretable and Flexible Target-Conditioned Neural Planners For Autonomous Vehicles

Learning-based approaches to autonomous vehicle planners have the potential to scale to many complicated real-world driving scenarios by leveraging huge amounts of driver demonstrations. However, prior work only learns to estimate a single planning trajectory, while there may be multiple acceptable plans in real-world scenarios. To solve the problem, we propose an interpretable neural planner to regress a heatmap, which effectively represents multiple potential goals in the bird's-eye view of an autonomous vehicle. The planner employs an adaptive Gaussian kernel and relaxed hourglass loss to better capture the uncertainty of planning problems. We also use a negative Gaussian kernel to add supervision to the heatmap regression, enabling the model to learn collision avoidance effectively. Our systematic evaluation on the Lyft Open Dataset across a diverse range of real-world driving scenarios shows that our model achieves a safer and more flexible driving performance than prior works

Safety-Critical Scenario Generation Via Reinforcement Learning Based Editing

Generating safety-critical scenarios is essential for testing and verifying the safety of autonomous vehicles. Traditional optimization techniques suffer from the curse of dimensionality and limit the search space to fixed parameter spaces. To address these challenges, we propose a deep reinforcement learning approach that generates scenarios by sequential editing, such as adding new agents or modifying the trajectories of the existing agents. Our framework employs a reward function consisting of both risk and plausibility objectives. The plausibility objective leverages generative models, such as a variational autoencoder, to learn the likelihood of the generated parameters from the training datasets; It penalizes the generation of unlikely scenarios. Our approach overcomes the dimensionality challenge and explores a wide range of safety-critical scenarios. Our evaluation demonstrates that the proposed method generates safety-critical scenarios of higher quality compared with previous approaches

The Antitumor Effects of Plasma-Activated Saline on Muscle-Invasive Bladder Cancer Cells in Vitro and in Vivo Demonstrate Its Feasibility as a Potential Therapeutic Approach

Muscle-invasive bladder cancer (MIBC) is a fast-growing and aggressive malignant tumor in urinary system. Since chemotherapy and immunotherapy are only useable with a few MIBC patients, the clinical treatment of MIBC still faces challenges. Here, we examined the feasibility of plasma-activated saline (PAS) as a fledgling therapeutic strategy for MIBC treatment. Our data showed that plasma irradiation could generate a variety of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in saline. In vivo tests revealed that pericarcinomatous tissue injection with PAS was effective at preventing subcutaneous bladder tumor growth, with no side effects to the visceral organs after long-term administration, as well as having no obvious influence on the various biochemistry indices of the blood in mice. The in vitro studies indicated that adding 30% PAS in cell culture media causes oxidative damage to the bladder transitional cells T24 and J82 through enhancing the intracellular ROS level, and eventually induces cancer cells\u27 apoptosis by activating the ROS-mediated Fas/CD95 pathway. Therefore, for an intracavity tumor, these initial observations suggest that the soaking of the tumor tissue with PAS by intravesical perfusion may be a novel treatment option for bladder cancer

1D Fluid model of RF-Excited Cold Atmospheric Plasmas in Helium with Air Gas Impurities

Cold atmospheric plasmas (CAPs) in helium with air gas impurities (HeþAir for abbreviation) compromise the discharge stability of helium and the chemical reactivity of air, having great prospects for various applications such as plasma biomedicine. However, different kinds of reactive species are produced in HeþAir CAPs but only a few of them could be measured, and the plasma chemistry is so complex that the reported simulation models are simplified to a large extent, such as neglecting the space variation of CAPs by using a 0D model. As a result, much remains unknown for HeþAir CAPs, which hinders the development of their applications. For that reason, a 1D fluid model of HeþAir CAPs is developed in this paper, incorporating 48 chemical species and 118 volume reactions, which are extracted from a complex chemistry set by a reported 0D model, and then the density distribution of reactive species, the power dissipation pathways, and the chemistry pathways among the reactive species are obtained as a function of air concentration from 500 to 10 000 ppm. It is found that O and NO are the dominant reactive oxygen species (ROS) and reactive nitrogen species (RNS), respectively. Taking the ROS as a whole, it is mainly produced by the electron impact dissociation and excitation of O2; taking the RNS as a whole, it is mainly produced by the oxidation of atomic nitrogen [N and N(2D)], and NO is the precursor for all the other RNS

Caractérisation expérimentale de l’effet de l’injection de bulles dans une couche limite turbulente

To investigate the effect of intermediate sized bubble injection into a turbulent boundary layer under a strong gravity effect, we measure the velocity field of two-phase flow in a horizontal cavitation tunnel with 2D Particle Tracking Velocimetry in vertical plane perpendicular to the upper wall and 1D Laser Doppler Velocimetry technique for longitudinal velocity component. In this study, we focus on an horizontal boundary layer where the Reynolds number, based on the thickness of momentum and external velocity is Re 3976. The air injection panel is located at the upper wall of the tunnel’s test section and it allows to cover the injection of a large range of bubble sizes (from 40 to 300 viscous lengths) as well as varying the void fraction between 0.01% and 0.11%. The results reveal that two flow regimes exist: with the increase of the global air injection, a longitudinal speed deficit is observed in the log zone altogether with a longitudinal speed increase in the sub-viscous layer and a Reynolds stress drop. This is in agreement with a phenomena of aspiration caused by the bubble buoyancy. Beyond a critical bubble size, wake bubbles are found in the flow and contribute to a drop in viscous friction and in turbulent shear stress in the near wall region, this phenomenon could be associated to a blowing effect.Cette étude a pour objectif de caractériser expérimentalement les effets de l’injection de bulles de tailles intermédiaire (millimétriques), soumises à un fort effet de gravité, sur un écoulement de couche limite turbulente. La configuration expérimentale est celle d’une couche limite horizontale en développement pour un nombre de Reynolds caractéristique, basé sur l’épaisseur de quantité de mouvement et la vitesse externe, Re= 3976. Le système d’injection d’air localisé sur la paroi supérieure du tunnel a permis de faire varier la taille des bulles dans une large gamme (de 40 à 300 longueurs visqueuses), et de faire varier le taux de vide moyen entre 0.01% et 0.11%. Nous avons mesuré la vitesse du liquide dans la zone interne de la couche par Vélocimétrie par Images de Particules en 2D, pour les composantes de vitesse dans le plan vertical et Vélocimétrie par effet Doppler en 1D pour la composante longitudinale. Les résultats montrent l’existence de deux régimes d’écoulement. Avec l’augmentation du débit global d’air injecté, un déficit de vitesse longitudinale se manifeste dans la zone logarithmique, associé à un excès de vitesse longitudinale dans la sous couche visqueuse et une diminution des tensions de Reynolds. Ceci est en accord avec un phénomène d’aspiration dû à la flottabilité induite par les bulles. Au-delà d’une certaine taille de bulles, des bulles de sillage sont présentes dans l’écoulement, contribuant ainsi à une diminution tant du frottement visqueux que du frottement turbulent en très proche paroi, associé à un effet de soufflage.ANR-ASTRID F-DRAIH

Fluid Model of Plasma-Liquid Interaction: The Effect of Interfacial Boundary Conditions and Henry\u27s Law Constants

Plasma–liquid interaction is a critical area of plasma science, mainly because much remains unknown about the physicochemical processes occurring at the plasma–liquid interface. Besides a lot of experimental studies toward the interaction, a few fluid models have also been reported in recent years. However, the interfacial boundary conditions in the models are different and the Henry\u27s law constants therein are uncertain; hence, the accuracy and robustness of the simulation results are doubtable. In view of this, three 1D fluid models are developed for the interaction between a plasma jet and deionized water, each of which has a unique interfacial boundary condition as reported in the literature. It is found that the density distribution of reactive species is nearly independent of the interfacial boundary conditions in both the gas and liquid phases, except for that in the interfacial gas layer with a thickness of several tens of micrometers above water. The densities of the reactive species with high Henry\u27s law constants (H \u3e 104) are much different in such gas layers among the interfacial boundary conditions. Moreover, some Henry\u27s law constants are changed in the models according to their uncertainty reported in the literature, and only the reactive species with low Henry\u27s law constants (H \u3c 1) have their aqueous densities following the change. These densities are very low in the plasma-activated water. It could be concluded that the simulation of plasma–liquid interaction is generally independent of the interfacial boundary conditions and the uncertainty in Henry\u27s law constants

Caractérisation expérimentale de l’effet de l’injection de bulles dans une couche limite turbulente

To investigate the effect of intermediate sized bubble injection into a turbulent boundary layer under a strong gravity effect, we measure the velocity field of two-phase flow in a horizontal cavitation tunnel with 2D Particle Tracking Velocimetry in vertical plane perpendicular to the upper wall and 1D Laser Doppler Velocimetry technique for longitudinal velocity component. In this study, we focus on an horizontal boundary layer where the Reynolds number, based on the thickness of momentum and external velocity is Re 3976. The air injection panel is located at the upper wall of the tunnel’s test section and it allows to cover the injection of a large range of bubble sizes (from 40 to 300 viscous lengths) as well as varying the void fraction between 0.01% and 0.11%. The results reveal that two flow regimes exist: with the increase of the global air injection, a longitudinal speed deficit is observed in the log zone altogether with a longitudinal speed increase in the sub-viscous layer and a Reynolds stress drop. This is in agreement with a phenomena of aspiration caused by the bubble buoyancy. Beyond a critical bubble size, wake bubbles are found in the flow and contribute to a drop in viscous friction and in turbulent shear stress in the near wall region, this phenomenon could be associated to a blowing effect.Cette étude a pour objectif de caractériser expérimentalement les effets de l’injection de bulles de tailles intermédiaire (millimétriques), soumises à un fort effet de gravité, sur un écoulement de couche limite turbulente. La configuration expérimentale est celle d’une couche limite horizontale en développement pour un nombre de Reynolds caractéristique, basé sur l’épaisseur de quantité de mouvement et la vitesse externe, Re= 3976. Le système d’injection d’air localisé sur la paroi supérieure du tunnel a permis de faire varier la taille des bulles dans une large gamme (de 40 à 300 longueurs visqueuses), et de faire varier le taux de vide moyen entre 0.01% et 0.11%. Nous avons mesuré la vitesse du liquide dans la zone interne de la couche par Vélocimétrie par Images de Particules en 2D, pour les composantes de vitesse dans le plan vertical et Vélocimétrie par effet Doppler en 1D pour la composante longitudinale. Les résultats montrent l’existence de deux régimes d’écoulement. Avec l’augmentation du débit global d’air injecté, un déficit de vitesse longitudinale se manifeste dans la zone logarithmique, associé à un excès de vitesse longitudinale dans la sous couche visqueuse et une diminution des tensions de Reynolds. Ceci est en accord avec un phénomène d’aspiration dû à la flottabilité induite par les bulles. Au-delà d’une certaine taille de bulles, des bulles de sillage sont présentes dans l’écoulement, contribuant ainsi à une diminution tant du frottement visqueux que du frottement turbulent en très proche paroi, associé à un effet de soufflage.ANR-ASTRID F-DRAIH