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Photoacoustic spectroscopy (PAS) based gas sensors with high sensitivity, wide dynamic range, low cost, and small footprint are desirable in energy, environment, safety, and public health. However, most works have focused on either acoustic resonator to enhance acoustic wave or optical resonator to enhance optical wave. Herein, we develop a gas sensor based on doubly resonant PAS in which the acoustic and optical waves are simultaneously enhanced using combined optical and acoustic resonators in a centimeter-long configuration. Not only the lower detection limit is enhanced by the double standing waves, but also the upper detection limit is expanded due to the short resonators. As an example, we developed a sensor by detecting acetylene (C2H2), achieving a noise equivalent absorption of 5.7 × 10−13 cm−1 and a dynamic range of eight orders. Compared to the state-of-the-art PAS gas sensors, the developed sensor achieves a record sensitivity and dynamic range.

This paper describes technical details and new scientific opportunities offered by the new High Power Laser Facility at the ESRF, opened to users since 2022. This facility enables laser-induced dynamic compression experiments probed by ultra-fast X-ray Absorption Spectroscopy at beamline ID24-ED. This capability allows to reach and probe more extreme pressure and temperature states and higher strain rates with respect to static compression, addressing open questions in fundamental, planetary and material science. [ABSTRACT FROM AUTHOR]

Objective: The objective of this prospective study was to assess possible changes in the position and shape of the temporomandibular joint (TMJ) articular disc in patients treated with two protocols of rapid maxillary expansion (RME) and face mask (FM) therapy. Methods: A sample of 88 patients with Class III or Class III subdivision malocclusions, aged between 6 and 13 years, were consecutively selected and divided into three groups (G): G1‐34 patients were treated with RME, followed by FM therapy; G2‐34 patients were treated using RME according to modified alternate rapid maxillary expansion and constriction (ALT‐RAMEC) protocol, followed by FM therapy. These treated groups were randomly (1:1 allocation ratio) distributed according to the two treatment protocols. G3 – Control Group – 20 untreated patients were followed. Magnetic resonance imaging (MRI) TMJs were obtained before (T1) and after (T2) a treatment period or follow‐up. McNemar test, Fisher's exact test and intra‐ and inter‐observer concordance (K) were performed (p ≤.05). Results: There were no statistically significant differences in the baseline cephalometric variables at T1 between the groups. There were statistically significant differences between the groups (p <.001) in relation to the disc shape in T1, since G1 (8 TMJs −11.76%) presented higher occurrences of altered forms in comparison with G2 (no changes). No significant differences were observed in disc position CM and OM (G1 – p >.999; G2 – p =.063; G3 – p =.500) and shape (G1 – p > 0.999; G2 – p =.250; G3 – not calculable), between T1 × T2, in any of the groups studied. Conclusion: The two treatment protocols did not have adverse effects on the position and shape of the TMJ disc, in a short‐term evaluation. [ABSTRACT FROM AUTHOR]

The climate and energy crisis requires immediate countermeasures. Renewable energy communities (RECs) are capable of enhancing the consumption of renewable energy, involving citizens with a leading role in the energy transition process. The main objective of a REC is to maximize the consumption of renewable energy by reducing the mismatch between energy supply and demand. This is possible through the use of strategies and technologies including energy storage systems. Among these, the use of thermal energy storage (TES) is an efficient strategy due to the lower investment required compared to other storage technologies, like electric batteries. This study aims to define the role of TES in RECs, through a bibliometric analysis, in order to highlight research trends and possible gaps. This study shows that the existing literature on TES does not present terms related to RECs, thus presenting a research gap. On the other hand, RESs address the topic of energy storage in the literature, without focusing on TES in particular but considering the general aspect of the topic. Therefore, this leaves open a possibility for the development of research on TES as a possible technology applied to a REC to maximize the renewable energy sharing. [ABSTRACT FROM AUTHOR]

In this article, the tracking control problem for a class of nonlinear time‐delay systems is investigated. In particular, a new methodology for the design and the digital implementation of observer‐based tracking controllers is provided for a class of control‐affine nonlinear systems with state delays. First, a procedure for the design of continuous‐time observer‐based tracking controllers ensuring the global asymptotic stability of the corresponding closed‐loop tracking error system is provided for the considered class of systems. Then, sufficient conditions are provided for the existence of a suitably fast sampling and of an accurate quantization of the input/output channels such that the digital implementation of the proposed continuous‐time observer‐based tracking controller ensures the semi‐global practical stability property of the related sampled‐data quantized closed‐loop tracking error system, with arbitrarily small final target ball of the origin. Moreover, it is shown that, in the special case of delay‐free nonlinear systems, the sufficient conditions provided for the digital implementation of the proposed continuous‐time observer‐based tracking controller can be strongly relaxed. In the theory here developed, time‐varying sampling periods and nonuniform quantization of the input/output channels are taken into account. The proposed results are validated through examples concerning a class of neural networks systems and a class of time‐delay systems including, as a special case, a delay‐free actuated inverted pendulum. [ABSTRACT FROM AUTHOR]