Installation of flat solar collectors (FSCs) has been increasing due to the zero cost of renewable energy. However, the performance of this equipment is limited by the area, the material and the thermophysical properties of the working fluid. To improve the properties of the fluid, metal and metal oxide nanoparticles have mainly been used. This paper presents the performance assessment of the FSCs using simple and hybrid carbon nanofluids of low thermal capacity. Energy and mass balance modeling was performed for this study. A parametric analysis was conducted to examine the impact of key variables on the performance of the solar collectors using simple graphite and fullerene nanofluids, as well as hybrid metal–oxide–carbon nanofluids. From the results of heat transfer in FSCs, using graphite and fullerene nanofluids, it can be concluded that adding these nanoparticles improves the convection coefficient by 40% and 30%, respectively, with 10% nanoparticles. The graphite and fullerene nanoparticles can enhance the efficiency of FSCs by 2% and 1.5% more than base fluid. As the decrease in efficiency using fullerene with magnesium oxide is less than 0.2%, fullerene hybrid nanofluids could still be used in FSCs.

In this work, the performance of a low-temperature solar collector (LTSC) is evaluated, using carbon nanoparticles in water as working fluid. The nanoparticles used are crystallized fullerenes, with a red parameter of 1.42 nm ± 0.5 nm, with different volume fractions in water. The thickness of the carbon film was approximately 140 to 520 nm. The study is divided into three parts: modeling and simulation of an LTSC, low-cost production and characterization of nanoparticles, and thermal evaluation of the LTSC. For the study, fullerenes were produced by microwave synthesis from a terpenoid resin (Camphor) and the nanoparticles were characterized by scanning electron microscopy (SEM) and High-Resolution Transmission (HRTEM). Tests were carried out with different volumetric flow rates, 0.0111 LT/s, 0.0166 LT/s and 0.0194 L/s, and two volumetric concentrations, 0.035% and 0.063%. The results obtained from the fullerene nanofluid showed an improvement in the thermophysical properties compared to the properties of water. The performance results showed that the efficiency increases up to 47.2% compared to that of water, with a volume fraction of 0.063%, and a flow rate of 0.0194 LT/s.

This study conducts a comparative performance analysis of three different low-temperature solar collector systems: flat plate solar collectors (FPCs), heat pipe evacuated tube solar collectors (HPETCs), and heat pipe flat plate solar collectors (HPFPCs). Key performance parameters, such as heat transfer coefficients, useful heat, and thermal efficiency, are analyzed under varying mass flow rate, fluid temperature, and antifreeze concentration. The objective is to evaluate the thermal performance of these systems using different heat transfer fluids, specifically water, and mixtures of 30% and 50% ethylene glycol and propylene glycol. The performance data indicate that the heat transfer coefficient in the HPFPC diminishes by 28% and 41% when antifreeze is employed at concentrations of 30% and 50%, respectively. Furthermore, the integration of heat pipes with water in a flat plate solar collector results in efficiency enhancements, with respect to FPCs, of up to 13% at a fluid temperature of 30 °C, and up to 21% at 80 °C. At the elevated fluid temperature of 80 °C, an efficiency increase of 13% is observed with a 30% ethylene glycol concentration. The incorporation of heat pipes leads to an efficiency improvement of up to 6.5% in comparison to traditional flat plate solar collectors. This study highlights the significant impact of fluid properties, affecting the convective heat transfer coefficient, on the overall efficiency of solar collectors, emphasizing the importance of optimizing fluid composition and operating conditions for enhanced thermal performance.

A prosthetic scheme is presented for the design of transtibial lower limb prostheses for replacement in users with moderate energy activities. It is based on elastic and rigid components that allow energy storage and return during the gait phases. The design is based primarily on the location of the centres of mass of the biological regions that are being replaced. A computational tool was developed to support the design, which calculates the location of the centres of mass. The results were verified against those obtained from healthy biological limbs of a population ranging in height from 150 cm to 189 cm. The calculation tool was found to have a variation of around 1%, which is considered acceptable and favours the stability of the prosthesis and its overall interaction to achieve a viable and functional design.

Financial inclusion should be shared with university students so that they link access to and use of financial products and services to low costs, without discrimination or inequality, to achieve the Sustainable Development Goals. This study aims to map the literature on the relationship between financial inclusion and undergraduate students within a contextual approach. The mapping was conducted through a scoping review, utilizing keyword pairwise searches, which we referred to as contextual constellations, as an emergent method. The search was conducted on the Web of Science and Scopus databases. The range of publications found ranges from 1973 to July 2024. The contextual analysis considered the following keywords: financial inclusion, undergraduate students, financial literacy, financial well-being, experiment, behavior, sustainable development goals, social and solidarity economy, decision, and innovation. The relationships were analyzed using VOSviewer software, version 1.6.20. The findings found the main articles that have contributed to knowledge about the relationship between financial inclusion and undergraduate students from the proposed context. Therefore, the research gaps in the relationship between financial inclusion and undergraduate students were identified. This research also offers the potential to conduct a mapping from a contextual perspective, identifying strong and weak relationships between research topics and keywords of interest.

En este trabajo se expone el desarrollo y fabricación de un módulo educativo destinado a facilitar la instrucción mediante experimentos prácticos en el campo de los circuitos eléctricos, empleando técnicas de impresión 3D basadas en la Fabricación por Filamento Fundido. El diseño se basa en un modelo comercial desactualizado, con el propósito de ofrecer opciones de sustitución para el equipamiento en el laboratorio de ingeniería mecánica, específicamente en el sector eléctrico. Se detalla el proceso de diseño aplicando principios de ingeniería mecánica y enfocándose en el prototipado acelerado. El módulo fue modelado en AutoCAD 2025 en su versión para estudiantes, preparado para impresión en Creality Print y producido con una impresora ENDER-3 V3 SE utilizando filamento de ácido poliláctico. Se incluyen las características definitivas del módulo creado, junto con los parámetros de impresión que facilitaron la obtención de un dispositivo operativo.