Label-Free Study of the Global Cell Behavior during Exposure to Environmental Radiofrequency Fields in the Presence or Absence of Pro-Apoptotic or Pro-Autophagic Treatments

It remains controversial whether exposure to environmental radiofrequency signals (RF) impacts cell status or response to cellular stress such as apoptosis or autophagy. We used two label-free techniques, cellular impedancemetry and Digital Holographic Microscopy (DHM), to assess the overall cellular response during RF exposure alone, or during co-exposure to RF and chemical treatments known to induce either apoptosis or autophagy. Two human cell lines (SH-SY5Y and HCT116) and two cultures of primary rat cortex cells (astrocytes and co-culture of neurons and glial cells) were exposed to RF using an 1800 MHz carrier wave modulated with various environmental signals (GSM: Global System for Mobile Communications, 2G signal), UMTS (Universal Mobile Telecommunications System, 3G signal), LTE (Long-Term Evolution, 4G signal, and Wi-Fi) or unmodulated RF (continuous wave, CW). The specific absorption rates (S.A.R.) used were 1.5 and 6 W/kg during DHM experiments and ranged from 5 to 24 W/kg during the recording of cellular impedance. Cells were continuously exposed for three to five consecutive days while the temporal phenotypic signature of cells behavior was recorded at constant temperature. Statistical analysis of the results does not indicate that RF-EMF exposure impacted the global behavior of healthy, apoptotic, or autophagic cells, even at S.A.R. levels higher than the guidelines, provided that the temperature was kept constant.     

基于CO2激光单点加热的微泡腔制备及其性能研究

为了简化微泡腔的制备工艺,在传统CO_2激光双向加热方案的基础上,采用CO_2激光单点加热毛细管。通过精确控制加热温度和气体流速,制备出半球形的微泡腔,进而通过调节激光光斑,增加加热面积的方式制备出球形的微泡腔。使用光学显微镜和原子力显微镜(AFM)对制备的球形微泡腔进行表征,并通过COMSOL仿真验证了所制备微泡腔的性能。所制备的微泡腔表面光滑,壁厚最薄处可达到亚微米量级。研究结果表明,通过CO_2激光单点加热制备的微泡腔的壁厚存在轻微的不均匀性,但其谐振Q值仍然较高,可广泛应用于传感领域。     

Contribution to DEMO reactor RH maintenance assessment

The scope of this paper is a preliminary assessment of the maintenance scheme in support of the European study for the next generation of fusion reactor: DEMO. Despite other fusion machine requiring remote handling maintenance operations, DEMO is supposed to work under steady state operational conditions. Therefore, requirement on the maintenance scheme is stronger. To target a good availability of the machine along machine operation plan, it is necessary to draw an adequate maintenance scheme. Indeed, due to the high fluxes generated by the plasma in the vacuum vessel, the first wall lifetime is limited, so the frequent replacement is necessary. On current fusion experimental machine, as first wall load conditions are less severe, DEMO condition implies high level of requirement on maintenance time. During DEMO lifetime, several full first wall replacements are expected. To provide access to the vacuum vessel machine for first wall removal, preparatory work is required to set the machine to adequate maintenance conditions and to open the machine properly, the same situation at the end of the maintenance period. Shutdown duration for first wall replacement should be as short as possible to reach the availability target of the machine. From this statement, the maintenance duration should not exceed 20% of the total lifetime of the reactor operation. First wall segmentation (i.e. total number of component to replace) has a high impact onto the replacement time. Considering the number of feasible designs for the first wall segmentation, we concentrate remote handling concept assessments one type of segmentation, the one minimizing the numbers of modules to replace [4], [5], [6]. Assumption on Divertor segmentation for these DEMO studies have similarities with Divertor ITER design; therefore ITER design output is relevant [1], [2]. We assume divertor removal performed in shadow time, while removing the other first wall modules.     

The heat treatment and the gelation are strong determinants of the kinetics of milk proteins digestion and of the peripheral availability of amino acids

This study aimed to determine the kinetics of milk protein digestion and amino acid absorption after ingestion of four dairy matrices by six minipigs: unheated or heated skim milk and corresponding rennet gels. Digestive contents and plasma samples were collected over a 7 h-period after meal ingestion. Gelation of milk slowed down the outflow of the meal from the stomach and the subsequent absorption of amino acids, and decreased their bioavailability in peripheral blood. The gelled rennet matrices also led to low levels of milk proteins at the duodenum. Caseins and β-lactoglobulin, respectively, were sensitive and resistant to hydrolysis in the stomach with the unheated matrices, but showed similar digestion with the heated matrices, with a heat-induced susceptibility to hydrolysis for β-lactoglobulin. These results suggest a significant influence of the meal microstructure (resulting from heat treatment) and macrostructure (resulting from gelation process) on the different steps of milk proteins digestion.     

Phase Separation and Spatial Morphology in Sodium Silicate Glasses by AFM,Light Scattering and NMR

The morphological and structural properties of sodium silicate (Na₂O–SiO₂) glasses were analyzed using atomic force microscopy (AFM) and light scattering following thermal treatments. AFM observations indicated that the glass surface microstructure evolves during the phase separation mechanisms from continuous interpenetrating phases in the spinodal decomposition process to separated droplets embedded in a continuous matrix for the nucleation/growth one. Raman mapping gave evidence of a phase separation through the nucleation/growth process with formation of silica‐rich clusters characterized by higher polymerization degree as separate droplets. The variations in inhomogeneities versus temperature investigated by Brillouin are exponential for spinodal decomposition and linear in the case of nucleation/growth mechanism. Nuclear magnetic resonance spectroscopy was used to investigate the spatial distribution of the various Q_n species present in thermally treated glasses and allows determining fractal dimension between two and three.     

Modular Functionalization of Electrodes by Cross‐Coupling Reactions at Their Surfaces

Due to the increasing importance of modified electrodes for many applications in nanotechnology, including molecular electronics, bioelectronics, and sensors, there is a need to find ways to chemically attach suitable molecular films onto the electrodes. Combining the electroreduction of aryl diazonium salts with the Sonogashira cross‐coupling reaction, a new modular technique to modify electrodes is presented. The new technique allows a wide range of functional groups to be introduced onto electrode surfaces with high surface coverage by the functional subunit. Various organic subunits, including redox chromophores, are successfully attached to platinum electrodes. The corresponding films are characterized using cyclic voltammetry, X‐ray photoelectron spectroscopy, atomic force microscopy, and contact‐angle measurements. The electroreduction of diazonium salts is successfully achieved on a broad variety of conducting and semiconducting surfaces, which shows that the technique is applicable to a broad variety of substrates.     

Spark Plasma Sintering of fine alpha-silicon nitride ceramics with LAS for spatial applications

Many space systems such as satellite mirrors and their supporting structures require to be made from very low-thermal expansion materials combining both high hydrostability and relatively high mechanical properties. In this study, we have applied the “composite concept” in order to explore the possibility of fabricating near zero thermal expansion silicon nitride based ceramics. Consequently, a negative thermal expansion material belonged to the lithium aluminosilicate family (LAS powder crystallized under de β-eucryptite structure) was introduced in an alpha-silicon nitride fine powder (5 and 20 vol% of LAS) and the resulting composite system was sintered by Spark Plasma Sintering (SPS) at 1400 and 1500 °C. In the case of 20 vol% LAS compositions, relatively well-densified ceramics (94.4% of the theoretical density) were produced without adding any further sintering additive. The addition of yttria and alumina oxides allowed enhancing the densification level up to 98.2% (20 vol% LAS compositions) or from 62.3% up to 96.7% of the theoretical density in 5 vol% LAS materials. Nevertheless, it was impossible to full consolidate silicon nitride/LAS composite ceramics at temperatures lower than the temperature at which β-eucryptite melts, even by using SPS technology. Moreover, because of the relatively low temperatures involved in SPS, the α to β-Si₃N₄ transformation was avoided, resulting in microstructures composed of fine equiaxed α-Si₃N₄ grains (<200 nm) and of a glassy phase. Even if the effect of having a very large negative thermal expansion material was lost during the sintering step (because of the β-eucryptite melting), ceramics containing only 20 vol% of LAS-based phase exhibited very interesting values as regards of mechanical properties (strength, hardness, toughness, and Young's modulus), thermal conductivity and thermal expansion coefficient. We discuss in this work why we are so interested in developing dense silicon nitride/LAS ceramics sintered without any further additive addition, even though β-eucryptite is melted during the process and the transformation to the β phase is avoided.     

Digital three-dimensional image correlation by use of computer-reconstructed integral imaging

We use integral images of a three-dimensional (3D) scene to estimate the longitudinal depth of multiple objects present in the scene. With this information, we digitally reconstruct the objects in three dimensions and compute 3D correlations of input objects. We investigate the use of nonlinear techniques for 3D correlations. We present experimental results for 3D reconstruction and correlation of 3D objects. We demonstrate that it is possible to perform 3D segmentation of 3D objects in a scene. We finally present experiments to demonstrate that the 3D correlation is more discriminant than the two-dimensional correlation.