Phase evolution and electrical behaviour of samarium-substituted bismuth ferrite ceramics

Bi_1-xSm_xFeO₃ (x?=?0.15–0.18) ceramics with high density were produced using spark plasma sintering. The effects of composition, synthesis conditions and temperature on the phase evolution were studied, using XRD, TEM and dielectric spectroscopy. The coexistence of the ferroelectric R3c, antiferroelectric Pnam and paraelectric Pnma phases was revealed, with relative phase fractions affected by both calcination conditions and Sm concentration. Experiments on powdered samples calcined at different temperatures up to 950?°C suggest higher calcination temperatures promote Sm diffusion, allowing samples to reach compositional homogeneity. The structural transitions from the Pnam and R3c phases to the Pnma phase were comprehensively investigated, with phase transition temperatures clearly identified. The dielectric permittivity, electrical resistivity and breakdown strength were increased upon Sm-substitution, while ferroelectric switching was suppressed. The polarization-electric field loop became increasingly narrow with increasing Sm-content, but double hysteresis loops, which may reflect a reversible antiferroelectric to ferroelectric transformation, were not observed.     

Prediction of individual learning curves across information visualizations

Confident usage of information visualizations is thought to be influenced by cognitive aspects as well as amount of exposure and training. To support the development of individual competency in visualization processing, it is important to ascertain if we can track users’ progress or difficulties they might have while working with a given visualization. In this paper, we extend previous work on predicting in real time a user’s learning curve—a mathematical model that can represent a user’s skill acquisition ability—when working with a visualization. First, we investigate whether results we previously obtained in predicting users’ learning curves during visualization processing generalize to a different visualization. Second, we study to what extent we can make predictions on a user’s learning curve without information on the visualization being used. Our models leverage various data sources, including a user’s gaze behavior, pupil dilation, and cognitive abilities. We show that these models outperform a baseline that leverages knowledge on user task performance so far. Our best performing model achieves good accuracies in predicting users’ learning curves even after observing users’ performance on a few tasks only. These results represent an important step toward understanding how to support users in learning a new visualization.     

Proteomics of Muscle Microdialysates Identifies Potential Circulating Biomarkers in Facioscapulohumeral Muscular Dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is caused by a complex epigenetic mechanism finally leading to the misexpression of DUX4 in skeletal muscle. Detecting DUX4 and quantifying disease progression in FSHD is extremely challenging, thus increasing the need for surrogate biomarkers. We applied a shotgun proteomic approach with two different setups to analyze the protein repertoire of interstitial fluids obtained from 20 muscles in different disease stages classified by magnetic resonance imaging (MRI) and serum samples from 10 FSHD patients. A total of 1156 proteins were identified in the microdialysates by data independent acquisition, 130 of which only found in muscles in active disease stage. Proteomic profiles were able to distinguish FSHD patients from controls. Two innate immunity mediators (S100-A8 and A9) and Dermcidin were upregulated in muscles with active disease and selectively present in the sera of FSHD patients. Structural muscle and plasminogen pathway proteins were downregulated. Together with the upstream inhibition of myogenic factors, this suggests defective muscle regeneration and increased fibrosis in early/active FSHD. Our MRI targeted exploratory approach confirmed that inflammatory response has a prominent role, together with impaired muscle regeneration, before clear muscle wasting occurs. We also identified three proteins as tissue and possibly circulating biomarkers in FSHD.     

Oxidation resistance of SIC-AlN ceramics coated by oxidation-assisted-pack cementation process

Liquid-phase-pressureless-sintered SiC-AlN-Y₂O₃ composites were coated by means of modified pack cementation process (OXPAC, OXidation-assisted-PAck Cementation) using rare-earth oxides, RE₂O₃ (RE = Sc, Er, Sm, Lu, Ho), as reactive powders. The coatings, composed by the oxidation products of SiC, AlN and rare-earth silicates, were adherent to the substrate, without porosity and with a thickness of 10 μm. The oxidation resistance of the coated SiC-AlN-Y₂O₃ ceramics was also investigated at 1500 °C for a period of 200 h. The coated samples showed specific weight gain lower than the uncoated and pre-oxidised samples. Furthermore, the specific weight gain linearly increased with the rare-earth cationic radius.     

Engineered organic/inorganic hybrids for superhydrophobic coatings by wet and vapour procedures

Siloxane/oxide hybrids have attracted growing attention thanks to their ability to modulate the surface energy, wettability, or self-lubricity of a material. Here, we compare two functionalisation procedures (chemical vapour deposition and wet impregnation) on substrate films composed by preformed oxide particles. Three kinds of particles, characterised by different natures (SiO₂ and TiO₂) and average particle size, were studied to highlight possible effects related to the chemical and morphological state of the substrate surface. Morphological characterisations were carried out using dynamic light scattering and scanning electron microscopy, while the structure of the hydrophobing layer was studied by combining Fourier transform infrared spectroscopy and solid-state nuclear magnetic resonance. The degree of functionalisation and the features of the siloxane layer vary significantly among the adopted oxides and functionalisation methods. The wettability features of the different hybrids closely mirror the results of the spectroscopic characterisations, giving rise to either Lotus leaf or patch-wise hydrophobic systems depending on the adopted conditions.