X‐ray Diffraction Study of the Effect of High‐Temperature Heat Treatment on the Microstructural Stability of Third‐Generation SiC Fibers

Third‐generation SiC fibers [High Nicalon S (HNS) and Tyranno SA3 (Ty–SA3)] were studied by X‐ray diffraction and transmission electron microscopy (TEM) after heat treatments in neutral atmosphere up to 1900°C. The microstructural changes in both materials were determined using a modified Hall–Williamson method introducing an anisotropy parameter taking into account the high density of planar defects. HNS fibers exhibit significant modifications in the coherent diffraction domains (CDD) size, which drastically increases from 24 to 70 nm in the range 1600°C–1900°C. TEM observations support these results. The residual microstrain values decrease from 0.0015 to 0.0005 between 1750°C and 1850°C. Similarly, the anisotropy parameter significantly decreases in the same temperature range. Concerning the Ty–SA3 fibers, no evolution in terms of CDD size and residual microstrain was observed. However, the anisotropy parameter decreases at 1800°C. TEM observations did not show noticeable grain growth. The grain size was found to be larger than the CDD and the planar defects density to decrease at high temperature. In both types of fibers, the CDD sizes are similar for the highest temperature heat treatments.     

Invar Like Behavior of the Cr2AlC MAX Phase at Low Temperature

The structure of Cr₂AlC has been studied using neutron scattering experiments performed in a temperature range running from room temperature down to 1.8 K. It is shown that the unit cell volume does not vary significantly below 80 K. This anomalous behavior, correlated with the existence of a weak ferromagnetic ordering revealed from superconducting quantum interference device experiments, is similar to that characteristic of Invar alloys. Just above the Curie temperature T_C ~ 73 ± 5 K, the Cr₂AlC undergoes significant distortions of the octahedron and triangular prisms units. Above 100 K, Cr₂AlC follows an usual thermal expansion.     

Formation Mechanisms of Ti3SnC2 Nanolaminate Carbide Using Fe as Additive

Reactive sintering of 3Ti:Sn:2C and 3Ti:Sn:2C:0.6Fe powder mixtures is studied in the temperature range 510°C–1200°C under argon. It is demonstrated that the recently discovered Ti₃SnC₂ phase is formed, provided that Fe is added to a 3Ti:Sn:2C reactant mixture within the synthesis conditions used. Using dilatometric and X‐Ray diffraction analyses, the formation mechanism of Ti₃SnC₂ is discussed. Results show that at low temperature (about 510°C), tin is consumed to form Fe_xSn_y intermetallics. At high temperature (about 1060°C), tin is newly available to form Ti₃SnC₂ due to the melting of Fe_xSn_y. Then, the intermediate phases, TiC and Ti₂SnC, and/or Ti₅Sn₃, TiC, C, and Ti are dissolved in the (Fe + Sn) liquid phase and Ti₃SnC₂ very likely precipitate from the melt. The second part of the study deals with the optimization of the Fe content in the initial 3Ti:Sn:2C reactant powder mixture to synthesize samples with larger Ti₃SnC₂ content by hot isostatic pressing.     

Evaluation of the Skin Peptide Defenses of the Oregon Spotted Frog Rana pretiosa Against Infection by the Chytrid Fungus Batrachochytrium dendrobatidis

Population declines due to amphibian chytridiomycosis among selected species of ranid frogs from western North America have been severe, but there is evidence that the Oregon spotted frog, Rana pretiosa Baird and Girard, 1853, displays resistance to the disease. Norepinephrine-stimulated skin secretions were collected from a non-declining population of R. pretiosa that had been exposed to the causative agent Batrachochytrium dendrobatidis. Peptidomic analysis led to identification and isolation, in pure form, of a total of 18 host-defense peptides that were characterized structurally. Brevinin-1PRa, -1PRb, -1PRc, and -1PRd, esculentin-2PRa and -PRb, ranatuerin-2PRa, -2PRb, -2PRc, and -2PRe, temporin-PRb and -PRc were identified in an earlier study of skin secretions of frogs from a different population of R. pretiosa known to be declining. Ranatuerin-2PRf, -2PRg, -2PRh, temporin-PRd, -PRe, and -PRf were not identified in skin secretions from frogs from the declining population, whereas temporin-PRa and ranatuerin-2PRd, present in skin secretions from the declining population, were not detected in the current study. All purified peptides inhibited the growth of B. dendrobatidis zoospores. Peptides of the brevinin-1 and esculentin-2 families displayed the highest potency (minimum inhibitory concentration = 6.25–12.5 μM). The study provides support for the hypothesis that the multiplicity and diversity of the antimicrobial peptide repertoire in R. pretiosa and the high growth-inhibitory potency of certain peptides against B. dendrobatidis are important in conferring a measure of resistance to fatal chytridiomycosis.     

Role of elongational viscosity of feedstock in extrusion-based additive manufacturing of powder-binder mixtures

The 3D printing of metals and ceramics by the extrusion of a powder/thermoplastic binder feedstock is an extrusion-based additive manufacturing (EAM) techn     

Comparative Genomics of Eight Fusarium graminearum Strains with Contrasting Aggressiveness Reveals an Expanded Open Pangenome and Extended Effector Content Signatures

Fusarium graminearum, the primary cause of Fusarium head blight (FHB) in small-grain cereals, demonstrates remarkably variable levels of aggressiveness in its host, producing different infection dynamics and contrasted symptom severity. While the secreted proteins, including effectors, are thought to be one of the essential components of aggressiveness, our knowledge of the intra-species genomic diversity of F. graminearum is still limited. In this work, we sequenced eight European F. graminearum strains of contrasting aggressiveness to characterize their respective genome structure, their gene content and to delineate their specificities. By combining the available sequences of 12 other F. graminearum strains, we outlined a reference pangenome that expands the repertoire of the known genes in the reference PH-1 genome by 32%, including nearly 21,000 non-redundant sequences and gathering a common base of 9250 conserved core-genes. More than 1000 genes with high non-synonymous mutation rates may be under diverse selection, especially regarding the trichothecene biosynthesis gene cluster. About 900 secreted protein clusters (SPCs) have been described. Mostly localized in the fast sub-genome of F. graminearum supposed to evolve rapidly to promote adaptation and rapid responses to the host’s infection, these SPCs gather a range of putative proteinaceous effectors systematically found in the core secretome, with the chloroplast and the plant nucleus as the main predicted targets in the host cell. This work describes new knowledge on the intra-species diversity in F. graminearum and emphasizes putative determinants of aggressiveness, providing a wealth of new candidate genes potentially involved in the Fusarium head blight disease.     

Ingested Ketone Ester Leads to a Rapid Rise of Acetyl-CoA and Competes with Glucose Metabolism in the Brain of Non-Fasted Mice

The role of ketone bodies in the cerebral energy homeostasis of neurological diseases has begun to attract recent attention particularly in acute neurological diseases. In ketogenic therapies, ketosis is achieved by either a ketogenic diet or by the administration of exogenous ketone bodies. The oral ingestion of the ketone ester (KE), (R)-3-hydroxybutyl (R)-3-hydroxybutyrate, is a new method to generate rapid and significant ketosis (i.e., above 6 mmol/L) in humans. KE is hydrolyzed into β-hydroxybutyrate (βHB) and its precursor 1,3-butanediol. Here, we investigate the effect of oral KE administration (3 mg KE/g of body weight) on brain metabolism of non-fasted mice using liquid chromatography in tandem with mass spectrometry. Ketosis (Cmax = 6.83 ± 0.19 mmol/L) was obtained at Tmax = 30 min after oral KE-gavage. We found that βHB uptake into the brain strongly correlated with the plasma βHB concentration and was preferentially distributed in the neocortex. We showed for the first time that oral KE led to an increase of acetyl-CoA and citric cycle intermediates in the brain of non-fasted mice. Furthermore, we found that the increased level of acetyl-CoA inhibited glycolysis by a feedback mechanism and thus competed with glucose under physiological conditions. The brain pharmacodynamics of this oral KE strongly suggest that this agent should be considered for acute neurological diseases.     

In Silico Identification of Potential Druggable Binding Sites on CIN85 SH3 Domain

Protein-protein interactions (PPIs) play a pivotal role in the regulation of many physiological processes. The dysfunction of some PPIs interactions led to the alteration of different biological pathways causing various diseases including cancer. In this context, the inhibition of PPIs represents an attractive strategy for the design of new antitumoral agents. In recent years, computational approaches were successfully used to study the interactions between proteins, providing useful hints for the design of small molecules able to modulate PPIs. Targeting PPIs presents several challenges mainly due to the large and flat binding surface that lack the typical binding pockets of traditional drug targets. Despite these hurdles, substantial progress has been made in the last decade resulting in the identification of PPI modulators where some of them even found clinical use. This study focuses on MUC1-CIN85 PPI which is involved in the migration and invasion of cancer cells. Particularly, we investigated the presence of druggable binding sites on the CIN85 surface which provided new insights for the structure-based design of novel MUC1-CIN85 PPI inhibitors as anti-metastatic agents.     

Prototyping and Validating a Non-immersive Virtual Reality Serious Game for Healthcare Fire Safety Training

Fire Technology - In a healthcare context, the success of a fire safety procedure in a real-life emergency mainly depends on staff decisions and actions. One of the factors influencing staff...