Assessing the interdependencies between scientific disciplinary profiles

The investigation of the dynamics of national disciplinary profiles is at the forefront in quantitative investigations of science. We propose a new approach to investigate the complex interactions among scientific disciplinary profiles. The approach is based on recent pseudo-likelihood techniques introduced in the framework of machine learning and complex systems. We infer, in a Bayesian framework, the network topology and the related interdependencies among national disciplinary profiles. We analyse data extracted from the Incites database which relate to the national scientific production of most productive world countries at disciplinary level over the period 1992–2016.     

Thermal wave interferometry for measuring the thermal diffusivity of thin slabs

Thermal wave interferometry applied to the evaluation of thermal diffusivity of freestanding coatings and single layers is herewith presented. Measurements on a set of eight different materials (oxides free copper, an aluminium alloy, Armco iron, AISI 316 stainless steel, Nimonic90 and IN738 nickel based alloys and Yttria partially stabilised Zirconia coatings) have been carried out. The corresponding thermal diffusivity values cover a very large range (about three order of magnitude). A comparison of 1D and 3D models has been done in order to optimise the main measurement parameters. Sample thickness, heating beam size and modulation frequency range have been selected in order to maximise the photothermal signal and its phase variation as a function of the frequency. Experimental results give evidence of a very good agreement between literature and experimental values for all samples confirming the capability of this technique for measuring the thermal diffusivity of thin slabs.     

Composite Cathodes for Proton Conducting Electrolytes

Different composite materials made of mixed protonic/electronic conductors, SrCe_0.9Yb_0.1O_3–δ (10YbSC) or BaCe_0.9Yb_0.1O_3–δ (10YbBC), and a mixed oxygen‐ion/electronic conductor, La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF), were investigated for cathode application in intermediate temperature solid oxide fuel cells (IT‐SOFCs) using a high temperature proton conducting BaCe_0.8Y_0.2O_3–δ electrolyte. Only the LSCF/10YbBC composite was found to be chemically stable. Area specific resistance (ASR) measurements were performed in wet air for LSCF/10YbBC cathodes, changing the weight ratio between the phases and the sintering procedure. The best performance was obtained for the composite cathode containing 50 wt.‐% of LSCF and 50 wt.‐% of 10YbBC, sintered at 1,100 °C. Electrochemical impedance spectroscopy (EIS) measurements of the tested cathodes showed two depressed semicircles in the middle and low frequency range, respectively. Performing ASR measurements at different p allowed us to attribute the two semicircles to charge transfer and oxygen diffusion processes, respectively. The microstructure of the LSCF/10YbBC(1:1) composite cathode was optimised changing the ratio of the particle sizes between the two phases. The lowest ASR values (0.14 Ω cm² at 700 °C) were observed for the LSCF/10YbBC(1:1) composite cathode with different particle size (sub‐micrometer particles for LSCF and nanometer particles for 10YbBC). Fuel cell polarisation curves demonstrated superior performance of the LSCF/10YbBC (1:1) cathode with respect to Pt.