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Electrostatic spray drying : advantages for thermosensitive actives
No full textInternational audienceSpray drying (SD) and freeze drying (FD) represent common methods utilized across various industries to achieve powdered final products. Electrostatic spray drying (ESD) is an emerging alternative as a continuous process to dry sensitive products without degradation, challenging the established drying techniques. This study aims to explore the efficacy of this process (ESD) in preserving the integrity of active components like oils, lactic acid bacteria (LAB), and enzymes. Additionally, a life cycle assessment (LCA) of these three drying technologies was conducted for a comprehensive evaluation. In oil encapsulation, the study showed that oxidation was significantly influenced by the formulation and the drying processes employed, where higher encapsulation efficiency resulted in lower degradation. This was observed, for instance, in the saponin composition dried with ESD. For LAB encapsulation, the results demonstrated higher preservation using FD and ESD. However, the impact of climate change using FD is twice superior to the ESD process. Finally, for enzyme application, β-gal activity was retained maximally while encapsulating using skim milk or maltodextrin. Specifically, regardless of drying technique, maltodextrin exhibited a maximum retention of β-gal activity, exceeding 30%. In all the case studies, ESD proved to excel in encapsulating thermosensitive actives, highlighting superior retention of native viability and properties compared to SD. Additionally, ESD generated results comparable to those achieved with FD. Therefore, ESD appears to be a promising method for high powder quality and a more sustainable process than FD and SD
Generalization of the Wong-Sandler mixing rule to a generic cubic equation of state: examples of use for systems of industrial interest (Hydrogen, CCUS, refrigeration)
No full textInternational audienceCubic equations of state (EoS) remain the most widely used models in chemical engineering, and their predictive capabilities are highly dependent on mixing rules (MR). Considered as one of the most accurate, Wong Sandler's (WS) MR, have been generalized in this work, to allow its use with all 2-parameter (PR, SRK, …) and 3-parameter (PT, mPT, NEOS, …) cubic EoSs. The procedure for implementing the generalized WS MR is presented and tested with PR, PT and its variants (mPT and NEOS) on vapor-liquid equilibrium (VLE) and density data on various classes of mixtures for different types of use (hydrogen, CCUS, refrigeration). The results clearly show the benefits of this type of MR, especially around the critical point and for density data without considering volume translation frequently used with PR and SRK EoS
Epoxy Vitrimer Formulation for Resin Transfer Molding: Reactivity, Process, and Material Characterization
No full textInternational audienceInitially bound for landfill or incineration due to strong limitations in their repair or recycling, thermoset composite materials have recently received considerable attention in order to improve their end-of-life. In this respect, vitrimers appear to be a solution of choice, as they possess the capability for topological reconfiguration through an associative exchange mechanism, imparting them glass-like properties at high temperatures. However, despite these advances, studies with particular focus on the process such as pultrusion, impregnation, and resin transfer molding (RTM) remain scarce. In this work, a detailed reactivity study was conducted on a vitrimer formulation based on disulfide exchange chemistry toward the RTM process, which includes the development of a time–temperature–transformation (TTT) diagram. On this basis, vitrimer plates were successfully prepared by RTM, yielding thermal and mechanical properties similar to the reference epoxy resin. Additionally, while exhibiting very competitive properties, the resulting vitrimer materials demonstrated the ability to be reshaped and reprocessed. This work covers resin formulation, reactivity, implementation into the RTM process and, ultimately, material and mechanical characterization
Effects of grain size and β fraction on the deformation modes of a Ti-6Al-2Sn-4Zr-2Mo-Si alloy with equiaxed (α + β) microstructures: Slip trace analysis and multiscale simulation of polycrystal plasticity
No full textInternational audienceThis study investigates the mechanisms behind the great mechanical properties observed at room temperature for a dual-phase Ti-6Al-2Sn-4Zr-2Mo-Si titanium alloy with equiaxed (α + β) microstructures. More precisely, analyzing the material deformation modes and the possible effects of β fraction and grain size was done to better understand such micromechanisms. With this idea in mind, uniaxial tensile deformation tests were performed at room temperature, and the resulting mechanical behaviors were analyzed. It was observed that increasing β fraction would enhance the overall ductility and work hardening while conversely decreasing the material resistance. Additionally, the material strengthening due to grain size effect, quantified by the Hall-Petch parameter, was also found to be dependent on β fraction. Slip trace analysis was conducted to understand the effects of grain size and β fraction on the activation of the basal , prismatic , and pyramidal slip systems and their critical resolved shear stress (CRSS) ratios were established. The qualitative study of CRSS ratios revealed that at smaller grain sizes, the basal slip systems were dominant (e.g. basal/prismatic CRSS ratio of 0.86 for d=2.98 µm) whereas the prismatic slip systems were prevalent and more easily activated for coarser grains (e.g. basal/prismatic CRSS ratio of 1.19 for d=4.21 µm). Such CRSS ratios were then used to identify the material parameters of a self-consistent multiscale model employed to reproduce the tensile behaviors. For a more quantitative analysis, the CRSS values were evaluated and correlated to grain sizes with Hall-Petch relations. Clear correlations regarding grain size and β fraction were found for the CRSS of prismatic and pyramidal systems. However, special attention was given to the ambiguous results regarding basal slip systems because of the potential manifestation of the compatibility stresses and grain boundary sliding mechanisms due to the higher density of grain boundaries at small grain sizes
Advanced Nickel-based Catalytic Materials on Hydroxyapatite: Effect of the Metal Particle Size on Tri-reforming of Methane
No full textInternational audienceA new strategy based on an organometallic approach for the preparation of Ni-based catalytic materials permitting to control the morphology and distribution of the nanoparticles on the support has been developed, leading to spherical, small (mean diameter below 5 nm) and homogenously distributed nickel nanoparticles on hydroxyapatite. The as-prepared materials were characterized by different techniques (N2-physisorption, powder X-ray diffraction, transmission electron microscopy, infrared spectroscopy, temperature programmed reduction, temperature-programmed desorption of ammonia, temperature-programmed desorption of carbon dioxide and thermogravimetric analyses, among the most relevant). The catalytic performance of these materials was evaluated in the tri-reforming of methane at 800-850 ºC and 1.4 bar (molar feed composition CH4:CO2:H2O:O2 = 63.3:30.7:0.04:5.95, gas hourly space velocity = 14.9 L·gcat-1·h-1), in view of syngas production. Outstanding catalytic performance, in terms of activity, selectivity and stability, were achieved with the catalysts prepared via an organometallic method precluding structural modifications on the support. A comparative study between these catalytic materials proved higher activity and stability of the aforementioned materials in comparison with those prepared by a conventional incipient wetness impregnation methodology, mainly associated to stronger metal support interactions and higher surface area
Domain shared features for visual inspection of complex mechanical assemblies based on synthetically generated data
No full textIssue du 16th international conference on quality control by artificial vision 2023 - AlbiInternational audienceEven though neural network methodologies have been established for a long time, only recently have they achieved exceptional efficacy in practical deployments, predominantly due to improvements in hardware computational capacity and the large amounts of available data for learning. Nonetheless, substantial challenges remain in utilizing deep learning in many domains, mainly because of the lack of large amounts of labeled data that are versatile enough for deep learning models to learn useful information. For instance, in mechanical assembly inspection, annotating data for each type of mechanical part to train a deep learning model can be very labor-intensive. Additionally, it is required to annotate data after each modification of mechanical part specification. Also, the system for inspection is typically not available until the first few samples are built to collect data. This paper proposes a solution for these challenges in case of the visual mechanical assembly inspection by processing point cloud data acquired via a three-dimensional (3D) scanner. To reduce the necessity for manually labeling large amounts of data, we employed synthetically generated data for both training and validation purposes, reserving the real sensor data exclusively for the testing phase. Our approach reduces the need for large amounts of labeled data by using synthetically generated point clouds from computer-aided design models for neural network training. Domain gap is a significant challenge for the usage of synthetically generated data. To reduce the domain gap, we used different preprocessing techniques, as well as a neural network architecture that focuses more on shared features that will not significantly change between synthetically generated data and real data from the 3D sensor
An innovative carrier for the formulation of amorphous solid dispersion by hot-melt extrusion with no further downstream processes: a case study with indomethacin
No full textInternational audienceThe aim of this work was to study the possibility to use SepitrapTM as a carrier for the formulation of amorphous solid dispersions by HME (hot melt extrusion) processing aiming solubility enhancement of poorly water-soluble drugs. SepitrapTM is a microencapsulated powder solubilizer designed to simplify the manufacture of drugs in oral solid forms, not yet tested for this purpose. The performance of SepitrapTM was evaluated in HME processing for amorphous solid dispersions of poorly-water soluble drugs with indomethacin as a model drug. The study was conducted using a twin-screw extruder, two compositions of SepitrapTM and different loads of indomethacin, demonstrating that SepitrapTM could represent a new range of carriers for amorphous solid dispersions for HME processing, reducing necessary downstream steps such as grindin
Supercritical CO2 assisted extrusion foaming of PLA- cellulose fibre composites: effect of fibre on foam processing and morphology
No full textInternational audienceThis work is focused on the effect of the content and length of cellulose fibres on PLA foams produced by extrusion-foaming process assisted by sc-CO2. The produced foamed samples were characterised by water pycnometry, modulated differential scanning calorimetry, and scanning electron microscopy. Increasing the length and the content of cellulose fibres results in a reduction of the expansion of the foams at a given die temperature. Nevertheless, long fibres at low content allows an increase of the longitudinal expansion of the foams. Furthermore, composite foams can be processed at a lower die temperature than neat PLA, providing a wider processing window. In general, the addition of cellulose fibres increases the crystallinity of the foams. Narrower cell size distributions and smaller cells are obtained when adding fibres, implying more homogeneous foam structure
A new reactive absorption model using extents of reaction and activities. II. Application to CO 2 absorption into aqueous MDEA solutions
No full textInternational audienceAbsorption into basic aqueous solutions is widely used for CO 2 separation from raw natural gas or from flue gases. This study implements a general steady-state model for reactive gas-liquid absorption. This work expands upon a first case study where the model was applied with the stagnant film theory (Whitman, 1923) to alkaline salts-water-CO 2 systems. This second case study uses the resulting Arrhenius expression to examine published CO 2 absorption and desorption flux data in MDEA-water-CO 2 system. Arrhenius parameters are optimised for the reaction CO 2 + MDEA + H 2 O ↔ HCO 3-+ MDEAH + with lnk (m 3 .mol-1 .s-1) = 16.69-6385/T (K). Results emphasise the role of CO 2 physical solubility representation in reactive absorption model overall performance. Global modelling is needed: kinetic parameters should be used together with all underlying parameters with which they were obtained. The relevance of activity-based modelling is shown, especially at high CO 2 absorption/desorption driving force
