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Transcatheter aortic valve replacement (TAVR) is an alternative technique to surgical valve replacement for over 300,000 patients worldwide. The valve material used in the TAVR is made of biological tissues, whose durability remains unknown. The success of the TAVR favors the research toward synthetic valve leaflet materials as an alternative to biological tissues. In particular, polyethylene terephthalate (PET) textile valves have recently proven durability over a 6-month period in animal sheep models. Excessive fibrotic tissue formation remains, however, a critical issue to be addressed. The aim of this work was therefore to investigate the potential of PET textiles covalently conjugated with polyethylene glycol (PEG), known for its antifouling properties, to modulate the fibrosis formation both in vitro and in vivo. For this purpose, the surfaces of heart valves made of PET textiles were functionalized with an atmospheric pressure plasma, leading to the formation of carboxylic acid (COOH) groups, further used for PEG-NH

Carbon anodes used in Hall–Heroult electrolysis cells are involved in both electrical and chemical processes of the cell. Electrical resistivity of anodes depends on electrical properties of its constituents, of which carbon coke aggregates are the most prevalent. Electrical resistivity of coke aggregates is usually characterized according to the ISO 10143 standardized test method, which consists of measuring the voltage drop in the bed of particles between two electrically conducing plungers through which the current is also applied. Estimation of the electrical resistivity of coke particles from the resistivity of particle bed is a challenging task and needs consideration of the contribution of the interparticle void fraction and the particle/particle contact resistances. In this work, the bed resistivity was normalized by subtracting the interparticle void fraction. Then, the contact size was obtained from discrete element method simulation and the contact resistance was calculated using Holm’s theory. Finally, the resistivity of the coke particles was obtained from the bed resistivity.

Hall-Héroult cell stability is highly affected by anode changing operations. Upon the insertion of a cold anode in the cell, a layer of molten cryolite freezes under the anode. The thickness, microstructure, and chemical composition of this layer vary as a function of time and its location in the cell. To better understand the evolution of the frozen layer, mandatory for the validation of numerical models, a measurement campaign was conducted on the anodes having a few hours of operation in the cell. The macrostructure of the selected frozen bath samples has been investigated using computed tomography while scanning electron microscope (SEM) has been used to qualify its microstructure. An energy-dispersive X-ray spectroscope (EDS) coupled to the SEM has revealed the chemical content. The results showed not only very different macrostructures between samples, but also significantly heterogeneous structure within the same sample. Nevertheless, for all samples, there is a clear distinction between the frozen cryolite and alumina/dusting phases, with the latter surrounding the cryolite matrix.

A large amount of energy is lost at the interface between materials in electrodes, reducing process energy efficiency. Thus, the characterization of thermo-electro-mechanical behaviour of the interfaces is necessary to support the numerical modelling as an essential step in improving the design of the anode connection. Experiments have been performed on carbon-cast iron-steel samples taken from the anode assembly. The samples have been designed and prepared in such a way that they are representative of the industrial sealing process.

The study of the deformation behaviour of the collector bar at conditions experienced within the aluminium reduction cell is of great importance to optimizing the efficiency and increasing the life span of the cell. This paper communicates the results of an experimental program carried out on the steel collector bar material (AISI 1006) to investigate its behaviour in relation to its thermal, mechanical and the creep properties. Tests were carried out in compression at low stresses, 0.5 to 2 MPa and high temperature, 900 °C. Different behaviour was observed at low stresses below 2 MPa, which can be characterised by time and applied stress level. For the test at 2 MPa, a conventional creep curve with dominating secondary creep region was obtained. Oxidation and corrosion were factors considered due to the aggressive environment of the test condition. Metallographic inspection showed effect of oxides on tested sample.

A new apparatus for characterizing electrical contact resistance and thermal contact conductance has been developed and tested. The heating of the samples inside the apparatus was achieved via induction heating of a stainless steel billet to create a powerful heat generator instead of the commonly used convection furnace. With this equipment, the thermo-electro-mechanical (TEM) behavior of metal-carbon and metal-metal interfaces can be reproduced using a controlled inert gas environment, temperature up to 1000°C and mechanical pressure up to 2 MPa. A major advantage of this new concept is that the temperature equilibrium of the samples can be reached quickly (within two or three hours) while precisely controlling the heat flux. Recent experimental results performed on steel-carbon samples show that this concept is feasible and very efficient. This apparatus will be used to establish the constitutive laws of interfaces for electrical contact resistance and thermal contact conductance in the electrode connections to support numerical modeling of the aluminium reduction cell.