Study of Xenon Mobility in the Two Forms of MIL-53(Al) Using Solid-State NMR Spectroscopy

The Al-based metal–organic framework (MOF) MIL-53­(Al) exhibits a structural transition between a large-pore (<i>lp</i>) form and a narrow-pore (<i>np</i>) one. Such change is induced by temperature, external pressure, or the adsorption of guest molecules. ¹²⁹Xe solid-state NMR experiments under static and magic-angle spinning (MAS) conditions have been used to study the <i>lp</i>–<i>np</i> transition in MIL-53­(Al) initially loaded with xenon gas under a pressure of 5 × 10⁴ Pa (at room temperature). The conversion of the <i>lp</i> form into the <i>np</i> one when the temperature decreases from 327 to 237 K and the reopening of the pores below 230 K are then observed. Furthermore, ¹H → ¹²⁹Xe cross-polarization under MAS (CPMAS) experiments demonstrate the possibility to observe the <i>np</i> phase at <i>T</i> ≤ 230 K, while the <i>lp</i> one is unseen because the xenon residence time is too short for successful cross-polarization transfer. Moreover, even for the <i>np</i> phase at 199 K, the xenon atoms still exhibit significant motion on time scale faster than a few milliseconds. We prove the exchange of Xe atoms between the <i>lp</i> and <i>np</i> forms at room temperature with the two-dimensional (2D) ¹²⁹Xe EXchange SpectroscopY (EXSY) NMR method. Using ¹²⁹Xe selective inversion recovery (SIR) experiments, the rate for this exchange has been measured at 43 ± 6 s^–1

Data from: Ultrasonic cavitation induces necrosis and impairs growth in three-dimensional models of pancreatic ductal adenocarcinoma

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is a rapidly increasing cause of mortality whose dismal prognosis is mainly due to overwhelming chemoresistance. New therapeutic approaches include physical agents such as ultrasonic cavitation, but clinical applications require further insights in the mechanisms of cytotoxicity. Three dimensional in vitro culture models such as spheroids exploit realistic spatial, biochemical and cellular heterogeneity that may bridge some of the experimental gap between conventional in vitro and in vivo experiments. Purpose: to assess the feasibility and efficiency of inertial cavitation associated or not with chemotherapy, in a spheroid model of PDAC. Methods: we used DT66066 cells ,derived from a genetically-engineered murine PDAC, isolated from KPC-transgenic mice (LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1- Cre). Spheroids were obtained by either a standard centrifugation-based method, or by using a magnetic nano-shuttle method allowing the formation of spheroids within 24 hours and facilitating their handling. The spheroids were exposed to ultrasonic inertial cavitation in a specially designed setup. Four conditions were studied: control, gemcitabine alone , US cavitation alone , US cavitation + gemcitabine. Five US inertial cavitation indexes, corresponding to increased US intensities, were evaluated . The effectiveness of treatment was assessed after 24 hours with the following criteria: spheroid size (growth), ratio of phase S cells (proliferation), proportion of cells in apoptosis or necrosis (cellular mortality). These parameters were assessed by quantitative immunofluorescence techniques. Results: The 3D culture model presented excellent reproducibility. Eight or nine spheroids were analyzed for each condition. Cavitation induced a significant decrease in the size of spheroids , an effect significantly correlated to an increasing cavitation index (p < 0.0001). The treatment induced cell death whose predominant mechanism was necrosis (p < 0.0001). There was a tendency to a synergistic effect of US cavitation and gemcitabine at 5μM concentration, however significant in only one of the cavitation indexes used (p = 0. 013). Conclusion: Ultrasonic inertial cavitation induced a significant reduction of tumor growth in a spheroid model of PDAC., with necrosis rather than apoptosis as a Cell dominant mechanism of cell death. More investigations are needed to understand the potential role of inertial cavitation in overcoming chemoresistance

Modélisation d'un tube par élément fini de type poutre enrichi permettant l'ovalisation de la section

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Frequency-domain simulation of power electronic systems based on multi-topology equivalent sources modelling method

International audienceElectroMagnetic Interference (EMI) simulation of power converters helps engineers in the design process. In this paper, we describe a frequency-domain simulation method based on the Multi-Topology Equivalent Sources (MTES) model. The aim is to reproduce the non-linear behavior of power switches for a fast evaluation of the conducted EMI. The method performance is validated on a DC-DC converter

Pseudo-Random Sonications for Brain HIFU

While transcranial high intensity focused ultrasound is used in clinics for treating essential tremor and proposed for many other brain disorders, this promising treatment modality requires high energy resulting eventually in undesired cavitation and potential side effects. In this project, we tested the hypothesis that using pseudo-random sonication, instead of CW, it could be possible to increase of the pressure cavitation threshold during intracranial brain HIFU treatment

Triaxial Cell for Determining Shielded Cable Transfer Impedance During Environmental Stress

International audienceTransfer impedance is a main characteristic to describe the shielding performance of shielded cables at least up to 1 GHz. Traditionally, methods like line-injection and triaxial cell have been used to characterize it at ambient laboratory conditions. While the ambient laboratory conditions might represent appropriate environmental conditions for some industries, in others, like automotive, they are only a small subset of the real conditions. Thus, there is a need to characterize the transfer impedance over different environmental conditions. In this article, the authors present and verify a new triaxial cell design that is aimed to provide reliable measurements during high thermal and mechanical stresses. First, the cell performance is compared to a commercial cell at laboratory ambient conditions. Then, measurements are performed with the new cell at highly accelerated life testing conditions. Under these high thermal and mechanical stress conditions the cell performance is verified, and results on typical shielded cable performance under the same conditions are given

SonicHoop: Using Interactive Sonification to Support Aerial Hoop Practices

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Developing a Universal Exchange Format for Near-Field Scan Data

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