Hydrogels are gaining widespread popularity in the biomedical field due to their extraordinary properties, such as biocompatibility, biodegradability, zero toxicity, easy processing, and similarity to physiological tissue. They have applications in controlled drug release, wound dressing, tissue engineering, and regenerative medicine. Among these applications, hydrogels as a controlled drug delivery system stands out, which releases active substances in precise amounts and at specific times. To explore the latest advances in the design of hydrogels, a literature review of articles published in indexed scientific journals, in Scopus and Science Direct, was carried out. This review aimed to discover and describe the most innovative hydrogel research with applications in the biomedical field; hydrogels synthesized with polymers of different origins were selected, such as; i. Natural (dextran, agarose, chitosan, etc.); ii. Synthetic (polyacrylamide, polyethylene glycol, polyvinyl alcohol, etc.); iii. Composites (interpenetrants, hybrid crosslinkers, nanocomposites, etc.). Comparative analysis revealed that hydrogels with composite materials show the most promise. These composite hydrogels combine the advantages of different polymers or incorporate additional components, offering enhanced properties and functionalities. In summary, hydrogels are versatile biomaterials with immense potential in biomedicine. Their unique properties make them suitable for diverse applications. However, innovative designs and formulations must continue to be explored to further advance the capabilities of hydrogels and expand their biomedical applications.

This review presents an analysis and discussion about heat transfer phenomena during quenching solid steel from high temperatures. It is shown a description of the boiling curve and the most used methods to characterize heat transfer when using liquid quenchants. The present work points out and criticizes important aspects that are frequently poorly attended in the technical literature about determination and use of the boiling curve and/or the respective heat transfer coefficient for modeling solid phase transformations in metals. Points to review include: effect of initial workpiece temperature on the boiling curve, fluid velocity specification to correlate with heat flux, and the importance of coupling between heat conduction in the workpiece and convection boiling to determine the wall heat flux. Finally, research opportunities in this field are suggested to improve current knowledge and extend quenching modeling accuracy to complex workpieces.

Composite materials based on polyaniline and graphite were prepared using in situ polymerization of an aniline monomer without any previous treatment. Three monomer/graphite weight ratios during polymerization were studied, which were 1:1, 1:2, and 1:3. The composite materials showed a nanochain-like structure whose dimensions vary with the graphite content. Materials were deposited over a fluorine-doped tin oxide (FTO) substrate to evaluate its capacitive performance. The electrochemical measurements carried out in a 0.1 M aqueous solution of H₂SO₄ showed that PANI-Gr1 composite electrode exhibits a capacitance of 238 F·g⁻¹ at 0.5 A·g⁻¹ within a potential window of 0–0.6 V vs. Ag/AgCl. At a current density of 4.0 A·g⁻¹, the PANI-Gr1 composite shows an energy density of 3.0 Wh·kg⁻¹ that is 30% higher than pure PANI, results due to an increase in electrical conductivity concomitant with the morphology change and surface area increase. Composite materials showed promising properties as easily processable and scalable electrodes for supercapacitors.

This work presents the non-destructive assessment of polymeric composites based on synthetic matrices low-density polyethylene (LDPE) and polystyrene (PS) enhanced with chitosan (CS) biopolymer for use in active packaging systems for moisture control. Composites were prepared by incorporating CS at different contents (1, 3 and 5 phr) into LDPE and PS matrices. To evaluate the structural and thermal alterations induced by biopolymer loading, the materials were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The composites’ water-regulating properties—specifically, moisture absorption, retention, diffusion, and water vapor transmission rate—were quantitively tracked. Furthermore, the mechanical integrity of both dried and water-exposed systems was assessed via Shore D hardness testing. The results reveal a direct correlation between CS concentrations and enhanced hydrophilic behavior and water absorption, primarily attributed to the polar hydroxyl and amine groups within its molecular structure. The composites maintained adequate mechanical strength even after water exposure, confirming their structural stability for practical applications. This study demonstrates that the incorporation of CS into non-polar synthetic matrices significantly improves water affinity without requiring chemical compatibilizers, representing a cost-effective route to develop responsive packaging. The promise of these composites as responsive materials for real-time environmental interaction is highlighted by the successful non-destructive monitoring of their performance. This research establishes the feasibility and efficacy of non-destructive monitoring techniques in developing active packaging technologies, accelerating the progress of polymer-based systems with integrated and tunable moisture regulation capabilities.

El TiO₂ se ha estudiado como un material fotocatalítico debido a su buena estabilidad y capacidad para degradar contaminantes orgánicos. Este tipo de material se utiliza en el control de la contaminación ambiental y en recubrimientos antimicrobianos y fotocatalíticos, entre otras aplicaciones. Dada la importancia actual de este material, en el presente trabajo se realizó la síntesis de nanopartículas de TiO₂ (NPsTiO₂) utilizando extracto de Ricinus communis. Para la obtención de las NPsTiO₂, el extracto vegetal y TiCl₄ se mezclaron en presencia de hidróxido de amonio NH₄OH y se mantuvieron en agitación constante durante 2 h a 80 °C; posteriormente, las nanopartículas fueron secadas y calcinadas a 500 °C durante 4 h. Las nanopartículas obtenidas se analizaron mediante FT-IR, donde se identificaron bandas asociadas a los grupos presentes en el extracto. El análisis por DRX mostró picos de difracción característicos de la fase anatasa, ubicados a 2θ = 25°, 37°, 48°, 53°, 62°, 68° y 74°. Por DLS, las NPsTiO₂ presentaron dos poblaciones con tamaños de 87 y 317 nm. En cuanto a su actividad biológica, las NPsTiO₂ presentaron actividad antibacteriana frente a Staphylococcus aureus, observándose un incremento de la actividad después de la irradiación con luz UV durante 30 min, mientras que bajo irradiación con luz solar no se observó actividad antimicrobiana. Asimismo, en la evaluación de citotoxicidad sobre células A549, utilizando concentraciones de 100 y 200 ppm, se observó el menor porcentaje de citotoxicidad a 200 ppm con irradiación UV y el mayor porcentaje a 100 ppm sin irradiación. Estos resultados evidencian que las NPsTiO₂ obtenidas mediante una ruta verde presentan actividad antibacteriana y un comportamiento diferencial sobre la viabilidad celular dependiendo de las condiciones de irradiación y concentración.