Assessment of elemental composition in commercial fish of the Bay of Cádiz, Southern Iberian Peninsula.

The assessment of trace metal content in our fish diet is important due to the adverse effect on human health. Despite the increasing interest about the fish quality, little information is available for Southern Spain, a region characterized by high seafood intake. Nine species from the Bay of Cádiz with high commercial value were selected. Similar values were measured in the nine studied species for most of the elements, except for the macroelements Ca and S, and the microelements Fe, Mn and As, which showed significant differences among species. Metal Pollution Index (MPI) did not differ among species, and it was similar to those obtained for other Atlantic and Mediterranean locations. The values measured for the nine species were below the health limits provided by World, European and Spanish legislations, indicating that, in general terms, consumption of these species is safe in the study area.

Natural Ventilation Characterization in a Classroom under Different Scenarios.

The COVID-19 pandemic has pointed to the need to increase our knowledge in fields related to human breathing. In the present study, temperature, relative humidity, carbon dioxide (CO2) concentration, and median particle size diameter measurements were taken into account. These parameters were analyzed in a computer classroom with 15 subjects during a normal 90-minute class; all the subjects wore surgical masks. For measurements, Arduino YUN, Arduino UNO, and APS-3321 devices were used. Natural ventilation efficiency was checked in two different ventilation scenarios: only windows open and windows and doors open. The results show how ventilation affects the temperature, CO2 concentration, and median particle diameter size parameters. By contrast, the relative humidity depends more on the outdoor meteorological conditions. Both ventilation scenarios tend to create the same room conditions in terms of temperature, humidity, CO2 concentration, and particle size. Additionally, the evolution of CO2 concentration as well as the particle size distribution along the time was studied. Finally, the particulate matter (PM2.5) was investigated together with particle concentration. Both parameters showed a similar trend during the time of the experiments.

Piezoelectric Energy Harvesting Controlled with an IGBT H-Bridge and Bidirectional Buck-Boost for Low-Cost 4G Devices.

In this work, a semi-submersible piezoelectric energy harvester was used to provide power to a low-cost 4G Arduino shield. Initially, unsteady Reynolds averaged Navier-Stokes (URANS)-based simulations were conducted to investigate the dynamic forces under different conditions. An adaptive differential evolution (JADE) multivariable optimization algorithm was used for the power calculations. After JADE optimization, a communication cycle was designed. The shield works in two modes: communication and power saving. The power-saving mode is active for 285 s and the communication mode for 15 s. This cycle consumes a determinate amount of power, which requires a specific piezoelectric material and, in some situations, an extra power device, such as a battery or supercapacitor. The piezoelectric device is able to work at the maximum power point using a specific Insulated Gate Bipolar Transistor (IGBT) H-bridge controlled with a relay action. For the extra power supply, a bidirectional buck-boost converter was implemented to flow the energy in both directions. This electronic circuit was simulated to compare the extra power supply and the piezoelectric energy harvester behavior. Promising results were obtained in terms of power production and energy storage. We used 0.59, 0.67 and 1.69 W piezoelectric devices to provide the energy for the 4G shield and extra power supply device.

Oscillating U-Shaped Body for Underwater Piezoelectric Energy Harvester Power Optimization.

Vibration energy harvesting (VeH) techniques by means of intentionally designed mechanisms have been used in the last decade for frequency bandwidth improvement under excitation for adequately high-vibration amplitudes. Oil, gas, and water are vital resources that are usually transported by extensive pipe networks. Therefore, wireless self-powered sensors are a sustainable choice to monitor in-pipe system applications. The mechanism, which is intended for water pipes with diameters of 2-5 inches, contains a piezoelectric beam assembled to the oscillating body. A novel U-shaped geometry of an underwater energy harvester has been designed and implemented. Then, the results have been compared with the traditional circular cylinder shape. At first, a numerical study has been carried at Reynolds numbers Re = 3000, 6000, 9000, and 12,000 in order to capture as much as kinetic energy from the water flow. Consequently, unsteady Reynolds Averaged Navier-Stokes (URANS)-based simulations are carried out to investigate the dynamic forces under different conditions. In addition, an Adaptive Differential Evolution (JADE) multivariable optimization algorithm has been implemented for the optimal design of the harvester and the maximization of the power extracted from it. The results show that the U-shaped geometry can extract more power from the kinetic energy of the fluid than the traditional circular cylinder harvester under the same conditions.

Experimental Evaluation of Perfluorocarbon Aerosol Generation with Two Novel Nebulizer Prototypes.

The potential of non-invasive ventilation procedures and new minimally invasive techniques has resulted in the research of alternative approaches as the aerosolization for the treatment of respiratory distress syndrome (RDS). The aim of this work was to design two nebulizer prototypes and to evaluate them studying the particle size distribution of the inhaled droplets generated with distilled water and two perfluorocarbons (PFCs). Different experiments were performed with driving pressures of 1⁻3 bar for each compound. An Aerodynamic Particle Sizer was used to measure the aerodynamic diameter (Da), the mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD). The results showed that both prototypes produced heterodisperse aerosols with Da mean values in all cases below 5 µm. The initial experiments with distilled water showed MMAD values lower than 9 µm and up to 15 µm with prototype 1 and prototype 2, respectively. Regarding the PFCs, relatively uniform MMAD values close to 12 µm were achieved. The air delivery with outer lumens of prototype 1 presented more suitable mass distribution for the generation and delivery of a uniform aerosol than the two half-circular ring geometry proposed in the prototype 2.

Experimental and Numerical Modeling of Aerosol Delivery for Preterm Infants.

Respiratory distress syndrome (RDS) represents one of the major causes of mortality among preterm infants, and the best approach to treat it is an open research issue. The use of perfluorocarbons (PFC) along with non-invasive respiratory support techniques has proven the usefulness of PFC as a complementary substance to achieve a more homogeneous surfactant distribution. The aim of this work was to study the inhaled particles generated by means of an intracorporeal inhalation catheter, evaluating the size and mass distribution of different PFC aerosols. In this article, we discuss different experiments with the PFC perfluorodecalin (PFD) and FC75 with a driving pressure of 4-5 bar, evaluating properties such as the aerodynamic diameter (Da), since its value is directly linked to particle deposition in the lung. Furthermore, we develop a numerical model with computational fluid dynamics (CFD) techniques. The computational results showed an accurate prediction of the airflow axial velocity at different downstream positions when compared with the data gathered from the real experiments. The numerical validation of the cumulative mass distribution for PFD particles also confirmed a closer match with the experimental data measured at the optimal distance of 60 mm from the catheter tip. In the case of FC75, the cumulative mass fraction for particles above 10 µm was considerable higher with a driving pressure of 5 bar. These numerical models could be a helpful tool to assist parametric studies of new non-invasive devices for the treatment of RDS in preterm infants.