[en] Short communication

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[en] A simple processing technology for oxide confined vertical-cavity surface-emitting lasers (VCSELs) fabrication is reported in this article. Results of the burn-in test up to the present-day show that the high temperature lifetime of the fabricated devices exceeded 70:00 h. The eye diagrams show that the devices can be modulated up to 10 Gbps

[en] Ceramic-Matrix Composites (CMCs) consist of a ceramic fiber architecture in a ceramic matrix, bonded together through a thin interphase. The present contribution is limited to non-oxide CMCs. Their constituents being oxidation-prone, they are protected by external coatings. We state here that CMCs display a hybrid feature, when at least one of their components is not homogeneous from a chemical or microstructural standpoint. Hybrid fiber architectures are used to tailor the mechanical or thermal CMC-properties whereas hybrid interphases, matrices and coatings to improve CMC resistance to aggressive environments.

[en] Electrostatic comb-drive actuators in electrolytes have many potential applications, the most popular of which is characterizing the mechanical properties of biological structures at small scales. Maximizing the utility of these devices for such applications requires a model capable of accurately predicting their behavior. The current state of the art model of these actuators assumes (i) that the native oxide is a pure dielectric, (ii) that the ion concentration of the bulk electrolyte is constant, and (iii) that the Stern layer can be neglected compared to the oxide layer. This model captures the general behavior of the electrostatic actuator in electrolytes, but has limited accuracy. We propose a hierarchy of models that addresses the suitability of these assumptions separately and in concert. We find that the model which removes assumptions (i) and (ii) is sufficient to accurately predict the displacement of a comb-drive actuator in electrolytes. (paper)

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[en] Chemical and structural information as obtained by Moessbauer spectroscopy when applied on the study of the catalysts under controlled temperature and pressure of the sample environment or under conditions close to the reaction ones is reviewed. Several cells for these in situ or operando measurements, respectively, are described: working at high and/or low temperature, under vacuum or rather high pressure, in a static atmosphere or in a flow, in gas or liquid phase, in the presence of magnetic fields or by applying the electric field. Examples of catalytic reactions being studied in such in situ cells are given, focusing on the oxide catalysts either crystalline or amorphous or on the oxide supported catalysts. The advantages of in situ measurements were noticed, especially for unraveling the reaction mechanism. (authors)