Glass reactive sintering as an alternative route for the synthesis of NZP glass–ceramics

The NZP-type crystal structure allows a large number of ionic substitutions which leads to ceramics with adjustable thermal expansion properties or interesting ionic conductivity. However, NZP is difficult to fabricate into monoliths because it requires both high temperatures and long sintering times. An alternative low temperature route to obtain a tungsten (IV) and tin (IV) containing NZP crystalline phase uses a process of glass reactive sintering of a phosphate glass. Using a microwave oven, a glass with the appropriate composition in the NaPO3–Sn(II)O–W(VI)O3 ternary diagram is prepared by a conventional melting and casting technique. After crushing, the glass powder is pressed at room temperature. The green pellet is cured during various times at temperatures where glass reactive sintering takes place. From XRD and DTA experiments, we have shown that different parameters influence the achievement of NZP phase. Consequently, specific conditions, such as (i) initial glass composition, (ii) equimolar quantities of SnO and WO3, (iii) glass particle size lower than 100 μm, and (iv) curing conducted under air, are required to obtain a glass–ceramic with a single crystalline phase with the NZP-type crystal structure.     

Ultrafast Doppler imaging of blood flow dynamics in the myocardium

Imaging intramyocardial vascular flows in real-time could strongly help to achieve better diagnostic of cardiovascular diseases. To date, no standard imaging modality allows describing accurately myocardial blood flow dynamics with good spatial and temporal resolution. We recently introduced a novel ultrasonic Doppler imaging technique based on compounded plane waves transmissions at ultrafast frame rate. The high sensitivity of this ultrafast Doppler technique permits to image the intramyocardial blood flow and its dynamics. A dedicated demodulation-filtering process is implemented to compensate for the large tissue velocity of the myocardium during the cardiac cycle. A signed power Doppler processing provides the discrimination between arterial and venous flows. Experiments were performed in vivo in a large animal open chest model ( N = 5 sheep) using a conventional ultrasonic probe placed at the surface of the heart. Results show the capability of the technique to image intramyocardial vascular flows in normal physiological conditions with good spatial (200 μm) and temporal resolution (10 ms). Flow dynamics over the cardiac cycle were investigated and the imaging method demonstrated a phase opposition of flow waveforms between arterial and venous flows. Finally, ultrafast Doppler combined with tissue motion compensation was found able to reveal vascular flow disruption in ischemic regions during occlusion of the main diagonal coronary artery.     

Circulating Monocyte Subsets and Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR), as an alternative to open heart surgery, has revolutionized the treatment of severe aortic valve stenosis (AVS), the most common valvular disorder in the elderly. AVS is now considered a form of atherosclerosis and, like the latter, partly of inflammatory origin. Patients with high-grade AVS have a highly disturbed blood flow associated with high levels of shear stress. The immediate reopening of the valve during TAVR leads to a sudden restoration of a normal blood flow hemodynamic. Despite its good prognosis for patients, TAVR remains associated with bleeding or thrombotic postprocedural complications, involving mechanisms that are still poorly understood. Many studies report the close link between blood coagulation and inflammation, termed thromboinflammation, including monocytes as a major actor. The TAVR procedure represents a unique opportunity to study the influence of shear stress on human monocytes, key mediators of inflammation and hemostasis processes. The purpose of this study was to conduct a review of the literature to provide a comprehensive overview of the impact of TAVR on monocyte phenotype and subset repartition and the association of these parameters with the clinical outcomes of patients with severe AVS who underwent TAVR.     

Optimal 3D arm strategies for maximizing twist rotation during somersault of a rigid-body model

Multibody System Dynamics - Looking for new arm strategies for better twisting performances during a backward somersault is of interest for the acrobatic sports community while being a complex...     

Hybrid Touch/Tangible Spatial 3D Data Selection

We discuss spatial selection techniques for three‐dimensional datasets. Such 3D spatial selection is fundamental to exploratory data analysis. While 2D selection is efficient for datasets with explicit shapes and structures, it is less efficient for data without such properties. We first propose a new taxonomy of 3D selection techniques, focusing on the amount of control the user has to define the selection volume. We then describe the 3D spatial selection technique Tangible Brush, which gives manual control over the final selection volume. It combines 2D touch with 6‐DOF 3D tangible input to allow users to perform 3D selections in volumetric data. We use touch input to draw a 2D lasso, extruding it to a 3D selection volume based on the motion of a tangible, spatially‐aware tablet. We describe our approach and present its quantitative and qualitative comparison to state‐of‐the‐art structure‐dependent selection. Our results show that, in addition to being dataset‐independent, Tangible Brush is more accurate than existing dataset‐dependent techniques, thus providing a trade‐off between precision and effort.     

Bioinspired Electro‐Thermo‐Hygro Reversible Shape‐Changing Materials by 4D Printing

Hygromorph composites are moisture‐induced shape‐changing materials that are increasingly studied to develop autonomously actuated deployable structures. The morphing mechanism is based on the high affinity for moisture and the hygroexpansive nature of at least one component, combined with a bilayer microstructure. Among available hygromorphs, those consisting of cellulosic or hydrogel material‐based actuators trigger fast responses to moisture. Their stiffness however decreases significantly with the moisture content and that restricts their potential application as soft actuators. This work proposes a novel 4D printed multistimuli‐responsive structural material based on conductive carbon reinforcements and combined with a moisture sensitive polymer. These 4D printed materials possess a microstructure that provides the capability of natural actuators like pine cones. The actuation of these functional materials could be either triggered passively by the variation of the ambient moisture, or by electroheating, with the latter leading to the control of the moisture content in initially wet samples via Joule effects. This new class of functional materials shows an increase of the actuation speed by a factor 10 compared to other existing hygromorphs with the same responsiveness. When the electrical heating is turned off, passive cooling and moisture driven actuation is triggered in a full reversible mode.     

High speed milling, electro discharge machining and direct metal laser sintering: A method to optimize these processes in hybrid rapid tooling

Prototype injection moulds for plastic parts must face two constraints: be designed and manufactured as quickly as possible and have a short lead time. Moreover, moulds have to evolve in the same way as the part does, to provide either a new functionality or a variant of this part. The current approach is based on a multi component tooling (hybrid rapid tooling) in order to more easily manufacture each component of the mould and to have a greater reactivity to each product evolution. In this paper, we propose a method to manufacture the mould in multi components. This approach is based on process capability criteria (i.e. topological and geometrical criteria). An industrial example is presented. We will focus on the choice between three processes mainly used in hybrid rapid tooling: high speed machining (HSM), electro discharging machining (EDM) and direct metal laser sintering (DMLS).     

Sensor fault detection and isolation filter for polytopic LPV systems: A winding machine application

In this paper, a fault diagnosis method is developed for a particular class of nonlinear systems described by a polytopic linear parameter varying (LPV) formulation. The main contribution consists in the synthesis of an accurate fault detection and isolation (FDI) filter and also a sensor fault magnitude estimation with a quality factor. This quality factor of the filter underlines if the fault estimation can be used or not. Stability conditions of the polytopic LPV filter are studied by ensuring poly-quadratic stability with Linear Matrix Inequality (LMI) representation. The effectiveness of this global FDI scheme through LPV modelization, filter design and stability analysis, is illustrated on a real winding machine under multiple sensor faults.     

An efficient numerical model for liquid water uptake in porous material and its parameter estimation

The goal of this study is to propose an efficient numerical model for the predictions of capillary adsorption phenomena in a porous material. The Scharfetter–Gummel numerical scheme is proposed to solve an advection–diffusion equation with gravity flux. Its advantages such as accuracy, relaxed stability condition, and reduced computational cost are discussed along with the study of linear and nonlinear cases. The reliability of the numerical model is evaluated by comparing the numerical predictions with experimental observations of liquid uptake in bricks. A parameter estimation problem is solved to adjust the uncertain coefficients of moisture diffusivity and hydraulic conductivity.