High-throughput approach to the catalytic combustion of diesel soot II: Screening of oxide-based catalysts

Following the development of a high-throughput (HT) methodology for the evaluation of diesel soot oxidation catalysts in a 16 parallel channels reactor, a library of over 60 catalysts was tested under optimized conditions. The catalyst compositions were chosen to include solids which specific properties like oxygen storage capacity, oxygen mobility and ionic conductivity. The key parameters for high activity appear related to the presence of active and mobile surface oxygen species, and to an appropriate catalyst particle size in order to favour the number of contacts with the soot. In contrast, high oxygen storage capacity and bulk oxygen ion mobility do not appear as relevant properties for high catalytic activity. Nine new formulations were found to perform better than the reference catalyst “high surface area (HSA) ceria” (Rhodia).     

Two‐Dimensional Nanomaterials for Biomedical Applications: Emerging Trends and Future Prospects

Two‐dimensional (2D) nanomaterials are ultrathin nanomaterials with a high degree of anisotropy and chemical functionality. Research on 2D nanomaterials is still in its infancy, with the majority of research focusing on elucidating unique material characteristics and few reports focusing on biomedical applications of 2D nanomaterials. Nevertheless, recent rapid advances in 2D nanomaterials have raised important and exciting questions about their interactions with biological moieties. 2D nanoparticles such as carbon‐based 2D materials, silicate clays, transition metal dichalcogenides (TMDs), and transition metal oxides (TMOs) provide enhanced physical, chemical, and biological functionality owing to their uniform shapes, high surface‐to‐volume ratios, and surface charge. Here, we focus on state‐of‐the‐art biomedical applications of 2D nanomaterials as well as recent developments that are shaping this emerging field. Specifically, we describe the unique characteristics that make 2D nanoparticles so valuable, as well as the biocompatibility framework that has been investigated so far. Finally, to both capture the growing trend of 2D nanomaterials for biomedical applications and to identify promising new research directions, we provide a critical evaluation of potential applications of recently developed 2D nanomaterials.     

Fracture Toughness to Understand Stretch-Flangeability and Edge Cracking Resistance in AHSS

The edge fracture is considered as a high risk for automotive parts, especially for parts made of advanced high strength steels (AHSS). The limited ductility of AHSS makes them more sensitive to the edge damage. The traditional approaches, such as those based on ductility measurements or forming limit diagrams, are unable to predict this type of fractures. Thus, stretch-flangeability has become an important formability parameter in addition to tensile and formability properties. The damage induced in sheared edges in AHSS parts affects stretch-flangeability, because the generated microcracks propagate from the edge. Accordingly, a fracture mechanics approach may be followed to characterize the crack propagation resistance. With this aim, this work addresses the applicability of fracture toughness as a tool to understand crack-related problems, as stretch-flangeability and edge cracking, in different AHSS grades. Fracture toughness was determined by following the essential work of fracture methodology and stretch-flangeability was characterized by means of hole expansions tests. Results show a good correlation between stretch-flangeability and fracture toughness. It allows postulating fracture toughness, measured by the essential work of fracture methodology, as a key material property to rationalize crack propagation phenomena in AHSS.     

The effect of lutein supplementation on visual fatigue: A psychophysiological analysis

We used psychophysiological technology to examine the effect of an oral supplement, a combination of lutein, zeaxanthin and blackcurrant extract (LUT), on visual fatigue, within the context of a randomized, double-blind, placebo-controlled cross-over trial. The LUT supplement and placebo samples were randomly assigned to thirteen participants, who took the samples for two LUT (and vice versa) for another 2 week. Each participant completed visual proof reading tasks for 2 h during each of four testing sessions. Saccade tests were administered before and after the proof reading task, during which the participants moved their eyes back and forth between two targets positioned in the center of two checkerboards. We recorded EEG, EOG, heart rate, and facial muscle potential/performance during the saccade tests. Blood pressure was measured and subjective fatigue and stress scores were collected before and after the proof reading task. We averaged EEG starting at saccade offset in order to analyze eye fixation related potentials (EFRP). Our results suggested that the proof reading task induced visual fatigue. An analysis of EFRP and other psychophysiological data revealed significant differences between the LUT and placebo conditions. These results suggest that supplementation with LUT could help to reduce symptoms of visual fatigue.     

Sol–Gel-Prepared Pure and Lithium-Doped Hexacelsian Polymorphs: An Infrared, Raman, and Thermal Expansion Study of the β-Phase Stabilization by Frozen Short-Range Disorder

Monoclinic and hexagonal forms of celsians (BaAl₂Si₂O₈) were synthesized by hydrolysis–polycondensation of Si/Al alkoxide mixtures. Dilatometry, Raman scattering, IR absorption, and X-ray diffraction techniques were used to identify various hexacelsian phases and their conversion into the monoclinic phase as a function of thermal treatments and doping. Emphasis is given to the relationship between the shrinkage behavior and the static and dynamic short-range disorders in the XO₄ tetrahedra (X = Si/Al) arrangement. The α hexagonal phase exhibits a well-defined α–β_HT transition at about 300°C but a statically disorderedβ_SD form, which does not vary very much with temperature and is very similar to the β_HT form obtained below 300°C for some materials. This statically disordered phase is preferentially observed for fast-sintered lithium-free compositions and transforms gradually in the ordered form by annealing above 1100°C. Such stabilization of the high-temperature phase by the static disorder arising from the peculiar synthesis through alkoxide hydrolysis and the gel route, which freeze the dynamic disorder of gel-forming entities in a static disorder at the gelation step, is discussed in the light of previously observed cases. The thermal expansion behavior is very sensitive to the synthesis conditions, doping, and thermal treatments. The ordered α phase is more easily achieved with lithium-doped compositions, but lithium addition shifts the hexagonal-to-monoclinic phase transformation onset toward lower temperatures and promotes complete transformation with thermal annealing.     

Kinetics and mechanism of radical polymerization of methylmethacrylate using p-acetylbenzylidene triphenylarsonium ylide (p-ABTAY) as an initiator

Solution polymerization of methylmethacrylate (MMA) initiated by p-acetylbenzylidene triphenylarsonium ylide in dioxane was carried out at 60±0.2 °C up to 10 hrs. in a polymerization tube under a nitrogen atmosphere. The values of the initiator and the monomer exponent were computed as 0.46 and 1.03, respectively. The overall activation energy and kp²/k_t were calculated as 53 KJ/mole and 1.19 × 10⁻² L/mol·s, respectively for the polymerization.     

Concomitant use of liquid–liquid batch and continuous plug flow reactors for kinetic model discrimination. Application to the Rh/TPPTS catalysed reduction of the C–C double bond in dimethylitaconate

The biphasic catalytic reduction of the C–C double bond of dimethylitaconate with a water soluble rhodium/triphenylphosphinetrisulphonated sodium salt (TPPTS) complex is investigated. Kinetic studies in a well-mixed batch reactor provide kinetics parameters and an activation energy of 71 kJ mol⁻¹ but cannot discriminate between a first order or a complex kinetic model within the range of substrate concentration where the approximation of linear liquid/liquid partition is respected. Catalytic tests in the centrifugal partition chromatograph (CPC) reactor under steady-state operations in chemical regime and plug flow mode allow discriminating the kinetic models, the complex kinetic rate law being preferred.     

Towards processible poly(pyrrol-2-ylsquaraines)

Summary In an attempt to produce a processible poly(pyrrol-2-ylsquaraine) by forming a copolymer of poly(pyrrol-2-ylsquaraine) with polymethylmethacrylate, two synthetic routes were utilised. The first included forming the polysquaraine and then polymerising the attached methacrylate groups to form the desired product and the second proceeded via the preformed methacrylate polymer, containing N-alkylpyrrole side chains, which was then condensed with squaric acid. Difficulties arose in the first route when the polysquaraine product was found to be insoluble, hence preventing any further polymerisation but partial solubility during the second procedure did allow bissquaraines to be formed and, as a consequence, the resultant product exhibited fluorescent properties. Yet the desired processible poly(pyrrol-2-ylsquaraine) was not achieved. Received: 30 October 1997/Revised version: 22 January 1998/Accepted: 23 January 1998