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[Display omitted] • The morphology of freeze tape cast electrodes for solid oxide cells were characterized by X-Ray tomography. • A particle-based model was built to synthetically impregnate the electrode 3D reconstructions. • A sensitivity analysis on the nanoparticle size and catalyst loading was carried out to optimize the electrode microstructure. • Influence of nanoparticles size and scaffold morphology on the catalyst percolating properties and number of active sites was indicated. Microstructural correlations of impregnated freeze tape cast scaffolds for solid oxide cells are studied by coupling experimental and modelling approaches. The functional and supporting layers of the hierarchical porous backbones are initially reconstructed by synchrotron X-ray micro- and nano-holotomography, respectively. A particle-based model was then built to numerically infiltrate the scaffold walls with hemispherical nanoparticles. The electrode microstructural properties are evaluated on the artificially impregnated electrodes as function of the catalyst loading. A parametric investigation on the effect of the nanoparticle size is performed to analyse the evolution of the electrode characteristics. It has been shown that the volume fraction of the infiltrated phase necessary to reach the percolating threshold is increased while increasing the nanoparticle size. The density of active sites presents a maximum as function of the catalyst loading that depends on the particle size. The volume fraction of infiltrated phase required to reach the percolating threshold in the diffusion layer is one order of magnitude lower than in the functional layer (∼1 vol% compared to 3–8 vol%, respectively). The analyses contained in this paper aim at guiding the manufacturing process to the shaping of innovative electrodes microstructures combining both high activation and mass transfer properties. [ABSTRACT FROM AUTHOR]

Abstract Objectives This study sought to describe the procedural and clinical outcomes of patients undergoing transcarotid (TC) transcatheter aortic valve replacement (TAVR) with the Edwards Sapien 3 device. Background The TC approach for TAVR holds the potential to become the optimal alternative to the transfemoral gold standard. Limited data exist regarding safety and efficacy of TC-TAVR using the Edwards Sapien 3 device. Methods The French Transcarotid TAVR prospective multicenter registry included patients between 2014 and 2018. Consecutive patients treated in 1 of the 13 participating centers ineligible for transfemoral TAVR were screened for TC-TAVR. Clinical and echocardiographic data were prospectively collected. Perioperative and 30-day outcomes were reported according to the updated Valve Academic Research Consortium (VARC-2). Results A total of 314 patients were included with a median (interquartile range) age of 83 (78 to 88) years, 63% were males, Society of Thoracic Surgeons mortality risk score 5.8% (4% to 8.3%). Most patients presented with peripheral artery disease (64%). TC-TAVR was performed under general anesthesia in 91% of cases, mostly using the left carotid artery (73.6%) with a procedural success of 97%. Three annulus ruptures were reported, all resulting in patient death. At 30 days, rates of major bleeding, new permanent pacemaker, and stroke or transient ischemic attack were 4.1%, 16%, and 1.6%, respectively. The 30-day mortality was 3.2%. Conclusions TC-TAVR using the Edwards Sapien 3 device was safe and effective in this prospective multicenter registry. The TC approach might be considered, in selected patients, as the first-line alternative approach for TAVR whenever the transfemoral access is prohibited. Sapien 3 device was safe and effective in our multicenter cohort. Graphical abstract [ABSTRACT FROM AUTHOR]

Due to the mixed ionic electronic conductive properties of the Lanthanum Strontium Cobalt Ferrite (LSCF) La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ compound, it is of great scientific and technological interest. Especially in the Solid Oxide Fuel Cell (SOFC) technology, this compound has receiving great attention as a cathode material. However, its chemical reactivity with the Yttria-stabilized Zirconia (YSZ) electrolyte still remains one of the main challenges, which demands a comprehension in the μm and sub-μm range. In order to address the reactivity issues locally in the micrometre scale range, 2D and 3D X-ray μ-diffraction and μ-fluorescence analysis have been performed on a pristine LSCF cathode layer. The cathode was deposited on a dense YSZ electrolyte substrate spaced by a thin Gadolinium doped Ceria Oxide (CGO) barrier layer in between LSCF and YSZ to limit the reactivity. The present approach offers a larger field of view in comparison to electron microscopy techniques. The method can provide a more representative information and may offer some insights on the reactivity distribution along the interfaces. The formation of micro SrZrO 3 inclusions in LSCF layer is then indubitably identified, as well as in the CGO/YSZ interface. [ABSTRACT FROM AUTHOR]

Background: Isolated exclusion of the non-coronary sinus (NCS) is an attractive strategy in valve-sparing aortic root surgery, which avoids the mobilisation and re-implantation of coronary ostia. However, the long-term durability of aortic valve repair and the fate of remnant sinuses of Valsalva remain unclear.Method: From January 2006 to December 2013, 29 patients underwent replacement of the ascending aorta extending to the NCS (group NCS) and 56 patients underwent a modified Yacoub procedure (group MY) in our centre by a single surgeon. Significant difference of preoperative parameters was observed between two groups in the presence of bicuspid aortic valve (41.4% vs 12.5%, p=0.002) and the diameter of the sinus of Valsalva (47.3±4.7 mm vs 51.5±4.9 mm, p=0.01).Results: The group NCS, as compared to the group MY, was associated with significantly shorter cardiopulmonary bypass time (106.6±40.5 min vs 138.4±37.5 min, p=0.001) and aortic cross clamping time (69.0±21.8 min vs 105.4±27.8 min, p<0.01). The mean follow-up was 11.5±2.8 years. No surgical re-intervention was performed for aortopathies of the aortic root; the neo-sinus were not dilated in either groups (38.2±4.2 mm vs 34.0±4.0 mm, p<0.01). The 10-year freedom from aortic valve-related re-operation was estimated to be 96.6±3.4% and 94.5±3.1% (p=0.58), and the cumulative 10-year survival rates were 95.2±4.6% and 85.6±4.7% (p=0.61) in the group NCS and the group MY, respectively.Conclusions: Aortic valve-sparing isolated NCS replacement can be safely performed in selected patients; its early outcomes, overall survival and long-term freedom from aortic valve-related or aortopathy-related re-intervention were comparable to those obtained with the Yacoub procedure. [ABSTRACT FROM AUTHOR]

• Electrochemical characterizations of Ni-3YSZ electrode in SOFC and SOEC conditions. • Electrochemical impedance spectra measured up to high steam partial pressure. • Electrode microstructure reconstructed by synchrotron X-ray holotomography. • Dynamic model with a micro kinetic elementary description for porous Ni-3YSZ cermet. • Reaction pathways and rate-limiting steps in SOFC and SOEC modes. The electrochemical reactions of hydrogen oxidation and steam reduction have been investigated for a porous cermet electrode made of Ni and 3YSZ. The electrochemical characterizations have been performed over a large range of gas compositions at 700°C. It has been shown that the fuel electrode response is activated by the potential under anodic current while a limiting current density appears under cathodic polarization. Moreover, the impedance diagrams exhibit a shape representative of a kind of finite-length Gerischer element with a low-frequency contribution sensitive to the steam content. To interpret these experimental results, a continuous dynamic model has been developed by describing the mass and charge transfers within the electrode. The reaction has been divided into a sequence of elementary steps considering two scenarios of charge transfer based on the oxygen and hydrogen spillover mechanisms. Three-dimensional reconstructions obtained by synchrotron X-ray nano-holotomography have been used to provide the cermet structural properties for the simulations. The numerical computations have shown that the hydrogen spillover scenario is the most appropriate mechanism to reproduce correctly the experiments. Besides, the electrode response is controlled by the charge transfer at triple phase boundary lengths, the oxygen vacancies migration in the 3YSZ network and a pure chemical surface process depending on the polarization. In fuel cell mode, desorption of water molecules from 3YSZ would co-limit the electrode response, while in electrolysis mode, the steam adsorption on Ni would become one of the rate determining steps. Finally, a sensitivity analysis has shown that surface diffusion would also play a key role in the electrode response. [ABSTRACT FROM AUTHOR]