IMT Mines Albi

Scale formation on reactor walls remains a major operational challenge in high-pressure acid leaching (HPAL) of nickel laterites, leading to reduced heat transfer efficiency, increased maintenance, and process downtime. This study investigates the influence of slurry solid content and acid-to-ore (A/O) ratio on autoclave scale formation during laterite leaching. Experiments performed under typical HPAL conditions (265 °C and ~50 bar) with laterite ore examined how these parameters affect metal extraction, scale quantity, and mineralogical composition. Scale deposits were quantified and analysed to determine their composition and to evaluate the precipitation tendency of potential scale-forming minerals through solution speciation and supersaturation behaviour during HPAL leaching. The results show that increasing slurry solids significantly promotes scale formation, producing denser and more strongly adherent deposits, while higher acid dosage further enhances precipitation of sulphate-bearing phases. Mineralogical analyses indicate that the scales are primarily composed of hematite, hydronium alunite, and magnesium sulphates, whose formation is driven by solution supersaturation during leaching. Elevated solids content also promotes incorporation of valuable metals into the scale matrix, leading to reduced nickel and cobalt recovery. In contrast, operation at moderate solids content and near-stoichiometric acid addition limits scale accumulation while maintaining high metal extraction. These findings highlight the coupling between HPAL operating conditions, solution chemistry, and fouling behaviour, and suggest an operational window for reducing scale formation without the use of chemical additives that may interfere with downstream processing. • Experimental study of autoclave wall scale under HPAL conditions (265 °C). • Scale mineralogy and morphology linked to solution chemistry evolution. • High solids promote denser scale with strong wall adhesion. • Operating window suggested to limit fouling without chemical additives.

Polyamide 6,6 (PA66) is a key engineering polymer, whose unique mechanical properties arise from strong interchain hydrogen bonding. However, its hygroscopic nature makes it highly sensitive to water uptake, which markedly alters its thermomechanical behavior. Contrary to traditional experimental approaches, this study uses atomistic molecular dynamics (MD) simulations to investigate the role of water in modifying the glass transition temperature (Tg) and the viscoelastic response of amorphous PA66. Simulations capture a nonmonotonic dependence of Tg on water content. At low water concentrations, isolated water molecules bind to amide groups and restrict chain mobility, while beyond ∼2.5 wt %, water clustering disrupts the hydrogen-bond network and causes a pronounced Tg depression. Analysis of amide-group fluctuations reveals a master correlation between local segmental dynamics and bulk density, verifying the known temperature-humidity equivalence in terms of density variation. The computed Young's modulus exhibits systematic softening with increasing temperature and water content, consistent with experimental trends, albeit a more pronounced impact of water at low temperatures. Time-temperature superposition behavior is observed for both dry and hydrated systems. This work provides molecular-scale information on the hygromechanical coupling in PA66 and demonstrates the ability of MD simulations to predict water-induced transitions that govern the macroscopic behavior of polyamides.

Amorphous solid dispersions (ASDs) are widely recognized as an effective formulation strategy to enhance the in vivo performance of poorly water-soluble drugs; however, their broader application is often limited by insufficient long-term physical stability especially if the drug load is higher than the saturation concentration of the drug in the polymer under standard storage temperature conditions. In this study, the objective was to investigate the functional role of a lipid coating in modulating physical stability and in vitro release and bioaccessibility of a supersaturated praziquantel amorphous solid dispersions (ASD-PZQ). ASD-PZQ systems composed of praziquantel and a vinylpyrrolidone–vinyl acetate copolymer was coated using two lipid-based formulations predominantly composed of either beeswax or tristearin. These lipid systems differ in chemical composition, physicochemical characteristics, and biopharmaceutical behavior, particularly with respect to lipid digestibility. Selected additives (surfactants) were incorporated to tailor manufacturability, stability, and coating functionality. As amorphous systems are particularly sensitive to moisture-induced recrystallization, the coated ASDs were deliberately directly exposed to harsh storage conditions, namely excessive humidity (60% RH) and their physical stability was monitored over a six-month period. To better capture the complexity of gastrointestinal processes, the bioperformance of the lipid coating was assessed using an in vitro multicompartmental digestion model. From a stability standpoint, the lipid coating reduced moisture-induced plasticization during storage. In terms of biopharmaceutical performance, ASD-PZQ coated with beeswax-based formulations exhibited enhanced bioaccessibility compared with uncoated ASD-PZQ, whereas tristearin-based coatings resulted in a prolonged drug release profile. Overall, this work demonstrates that a lipid coating on supersaturated amorphous solid dispersions would mitigate key stability challenges associated with ASD development but also enables the introduction of new functional attributes. These findings position lipid-coated ASDs as advanced, multifunctional drug delivery systems for poorly water-soluble compounds and reinforce their relevance as high-value platforms in pharmaceutical research. • Lipid hot melt coating improves stability and performance of praziquantel solid dispersions • Lipid coating reduces moisture-induced plasticization of praziquantel solid dispersions • Beeswax-based coating formulation best limits mobility and delays drug recrystallization • Tristearin-based coating formulation protects from moisture and delays recrystallization • Lipid digestion enhances solubilization and biopharmaceutical performance

Mechanochemistry enables selective access to fcu and hcp UiO-66 phases starting from PET bottles and coloured textile waste.

This work is devoted to the synthesis, the characterization, and the evaluation of hydroxyapatite-supported ruthenium catalysts, with or without Ba and/or Cs promotion. Thus, a series of catalysts containing Ru, Cs, and Ba was synthesized by the incipient wetness impregnation method. Such catalysts are characterized by different physicochemical methods, providing insights into their properties. These catalysts are evaluated in the ammonia synthesis reaction at 350-500 °C and 10-25 bar. Sample 1Ru/hydroxiapatite (HAP), without promoter, shows a negligible catalytic activity, due to the formation of large Ru nanoparticles, which are not favorable for the formation of ammonia. On the other hand, the addition of Cs and Ba improves the catalytic performance, and Ba is found to be better than Cs. The pretreatment of the barium-containing catalysts under Ar flow at 600 °C is also found to be crucial for the decomposition of barium nitrate into barium oxide, thereby enhancing catalytic activity.

Abstract Strong metal–support interactions can significantly influence catalytic performance. On titania supports, these interactions often involve the formation of a substoichiometric TiO X overlayer during high‐temperature reduction, which can be reversed by treatments under dioxygen. Under CO 2 hydrogenation conditions, where water is produced, complete removal of the TiO X overlayer has been reported, raising questions about its stability in the presence of a mild oxidant such as CO 2 . In this study, in situ and operando techniques were employed to examine the effect of varying conditions on both the titania overlayer and cobalt species in a Co/TiO 2 catalyst. After reduction at 350 °C, the overlayer consisted of stoichiometric anatase TiO 2 , while cobalt remained partially reduced. Exposure to CO 2 /H 2 at 220 °C enabled complete cobalt reduction without affecting the TiO 2 overlayer. In contrast, pure CO 2 at 220 °C caused overlayer removal and full cobalt oxidation. The impact of this CO 2 ‐mediated reversibility on CO 2 hydrogenation was also evaluated. Although steady‐state activity was largely unaffected, the transient regime showed substantial changes in selectivity and behavior. These results demonstrate that different treatments can strongly influence both the stability and reactivity of Co/TiO 2 catalysts, highlighting the importance of dynamic SMSI effects in CO 2 hydrogenation.

ABSTRACT Probing stiffness anisotropies in three-dimensional materials non-destructively is a major challenge in disciplines as diverse as aeronautics and medicine. While the former typically relies on various mechanical tests—such as tensile, compression, bending, and shear—performed on sample parts, the latter often employs acoustic techniques or wave propagation through matter. The choice of techniques will depends on the size of the sample of interest and the desired resolution. In our case, to probe the mechanical properties of sub-millimetre micro-tissues, it is necessary to use methods with high resolution and as furtive as possible. We present a method based, 1/ on imaging the displacement of microbeads within a hydrogel resulting from the growth of a three-dimensional micro-tissue and, 2/ on finite element modelling of the deformations underlying bead displacements. This approach allows us to determine the elastic properties of the hydrogel and, in particular, to show that beyond a certain thickness, incomplete cross-linking of the hydrogel results in a stiffness gradient. We show that when the micro-tissue contacts with an immediately rigid alginate wall, the pressure exerted over time increases very rapidly, whereas when the micro-tissue encounters a substrate with a stiffness gradient, the pressure increase is more gradual. Uncovering this could provide a better understanding of the role of tumour microenvironment stiffness in metastatic escape processes.