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The exploitation of phonon-polaritons in nanostructured materials offers a pathway to manipulate infrared (IR) light for nanophotonic applications. Notably, hyperbolic phonon-polaritons (HP2) in polar bidimensional crystals have been used to demonstrate strong electromagnetic field confinement, ultraslow group velocities, and long lifetimes (up to ∼12 ps). Here we present nanobelts of α-phase molybdenum trioxide (α-MoO3) as a low-dimensional medium supporting HP2 modes in the mid- and far-IR ranges. Through real-space nanoimaging techniques with synchrotron and tunable laser IR light, we observe HP2 Fabry-Perot resonances that demonstrate distinct anisotropic propagation and frequency dependence. We remark an anisotropic propagation that critically depends on the frequency range. Our findings are supported by the convergence of experiment, theory, and numerical simulations. Our work shows that the low dimensionality of natural nanostructured crystals, like α-MoO3 nanobelts, provides an attractive platform to study polaritonic light-matter interactions and offers appealing cavity properties that could be harnessed in future designs of compact nanophotonic devices.

The use of radioactive isotopes in radioactive decay studies can be a problem due to the manipulation of radioisotopes, expensive equipment, and the difficulty of finding samples with a reasonable half-life (between 1 and 10 min). In this paper, we present a mock-up of a Geiger-Mu¨ller counter plus three fictitious radioisotopes. They form an experimental kit that teachers and professors can use in laboratories of schools and universities. Inside the Geiger electronic box, an Arduino board can recognize the isotope specimen sample the student inserts in the Geiger-Mu¨ller tube support. Once the measuring process starts, the Arduino simulates the particle counting as a function of time for that chosen isotope. The complete kit presented here costs approximately US$ 20.00, and it can be an alternative to other simulations for radioactive decay lessons.

Malus's law states that the intensity of light after passing through two polarizers is proportional to the square of the cosine of the angle between the polarizers. We present a simple setup demonstrating this law. The novelty of our work is that we use a multi-turn potentiometer mechanically linked to one of the polarizers to measure the polarizer's rotation angle while keeping the other polarizer fixed. Both the potentiometer and light sensor used to measure the transmitted light intensity are connected to an Arduino board so that the intensity of light is measured as a function of the rotation angle.

The popularization of microcontrollers like Arduino bring new possibilities of experiments for physics laboratories. For instance, load cell sensors have been used in experiments on impulse and buoyancy. Here we propose an experimental apparatus using Arduino connected to a load cell to measure surface tension by the du Noüy method (or ring method). The load cell gives the instantaneous and the maximum force value achieved during the experiment. This apparatus is presented as a simple and low-cost opSensorstion for physics laboratories.

Most of the practical applications in electrocatalysis require porous electrodes, built by dispersing the nanoparticles (NPs) on a gas diffusion layer, as carbon paper (CP). The lack of correlation between classic measurements in clean, controlled surfaces and thin films with those of porous electrodes, used in practical application, is largely neglected. Since catalysis depends on the area available, it is clear that the distribution of the NPs on the porous material is pivotal to the efficiency of the catalyst. Here we show a low‐cost method to disperse NPs on CP assisted in ultrasonic bath. Such method improves the Pt/C NPs distribution over the CP compared to the immersion method. As proof‐of‐concept, we show an increase in output current by using Pt/C/CP for 10 mM glucose electrooxidation and O2 eletroreduction in buffered solution at 37 °C, which is ascribed to the increase in collision factor. Furthermore, the cathodic reaction is facilitated compared to electrodes prepared by immersion, yielding an unprecedented open circuit voltage of 800 mV for the coupled reaction. The glucose/oxygen reaction is also investigated in passive flow in an H‐type cell to produce power. This concept shows promising application to build any kind of porous electrodes with improved area utilization. [ABSTRACT FROM AUTHOR]

A nanosensor and microsensor fabrication method employing scanning probe microscopy (SPM) is demonstrated. Within such process, nano- or microscale metal oxide (MoO(x) or TiO(x)) structures, constituting the active region of a sensor, are directly fabricated onto a microscopic metal track via SPM-assisted local anodic oxidation (LAO). Two distinct LAO routes, a slow (conventional) or a fast (unusual) one, are employed to produce nano- and microsensors, which are tested at different temperatures using CO2 and H2 as test gases. Sensitivities down to ppm levels are demonstrated, and the possibility of easy integration into microfabrication processes is also discussed.