Search Results (658)

Service learning (SL) is at a pivotal moment as education systems worldwide confront the challenges and opportunities posed by artificial intelligence (AI) and digital technologies. This scoping review synthesizes regional perspectives on SL and examines the barriers to its implementation in higher education. This study adopts a methodological approach widely used in prior educational research, enriched with selected PRISMA processes, namely identification, screening, and eligibility, to enhance its transparency and rigor. A total of 101 peer-reviewed articles were analyzed, using a mixed methods approach. Results are presented for six regions, Africa, Asia, Latin America, Europe, North America, and Oceania, revealing context-specific constraints, such as technological infrastructure, policy frameworks, linguistic diversity, and socio-economic disparities. Common barriers across regions include limited faculty training, insufficient institutional support, and misalignment with community needs. AI is explored as a potential enabler of SL, not as an empirical outcome, but as part of a reasoned argument emerging from the documented complexity of SL implementation in the literature. Ethical considerations, including algorithmic bias, equitable access, and the preservation of human agency, are addressed, alongside mitigation strategies that are grounded in participatory design and community engagement. This review offers a comparative, context-sensitive understanding of SL implementation challenges, providing actionable insights for educators, policymakers, and researchers, aiming to integrate technology-enhanced solutions responsibly. Full article

The paradigm of reinforcement learning (RL) refers to agents that learn iteratively through continuous interactions with their environment. However, when the value function is unknown, a neural network is used, which is typically encoded into an unknown temporal difference equation. When RL is implemented in physical systems, explicit convergence and stability analyses are required to guarantee the worst-case operations for any trial, even when the initial conditions are set to zero. In this paper, physical RL (p-RL) refers to the application of RL in dynamical systems that interact with their environments, such as robot manipulators in contact tasks and humanoid robots in cooperation or interaction tasks. Unfortunately, most p-RL schemes lack stability properties, which can even be dangerous for specific robot applications, such as those involving contact (constrained) tasks or interaction tasks. Considering an unknown and disturbed DAE2 robot, in this paper a p-RL approach is developed to guaranteeing robust stability throughout a continuous-time-adaptive actor–critic, with local exponential convergence of force–position tracking error. The novel adaptive mechanisms lead to robustness, while an integral sliding mode enforces tracking. Simulations are presented and discussed to show our proposal’s effectiveness, and some final remarks are addressed concerning the structural aspects. Full article

Microbial fuel cells (MFCs) can have high pollutant removal efficiencies and generate electricity; however, the use of selective membranes represents a considerable expense. In this investigation, the performance of a membraneless MFC was evaluated at different hydraulic retention times (HRTs) of 12, 24, 36, and 48 h. The chemical oxygen demand removal efficiencies (CODREs) were 93.5, 90.9, 87.3, and 85.4%, and the biochemical oxygen demand (BODRE) values were 94.5, 91.5, 88.9, and 85.5 at HRTs of 48, 36, 24, and 12 h, respectively. Lower concentrations of solids (suspended solids and total dissolved solids), total nitrogen, phosphorus, fats and oils, and microbiological contamination (helminth eggs and fecal coliforms) were detected when operating the system at a 48 h HRT. At an HRT of 12 h, no decrease in electrical conductivity was detected, whereas at 48 h, it decreased by 19.6%. The oxidation–reduction potential and OCV increased at longer HRTs. The microorganisms detected at the anode were Achromobacter denitrificans, Achromobacter anxifer, and Pseudomonas aeruginosa. The 48 h HRT improved the chemical, physical, and microbiological quality of the municipal wastewater, favoring voltage generation. Full article

Development of site index models for shrubby species in arid ecosystems remains a challenge, due to the absence of dominant height–age relationships and the complexity of ecological drivers in these environments. In this study, a multivariate approach to classify site quality for Agave lechuguilla Torr, a wild non-timber species of ecological and economic importance in northern Mexico, was performed. Data were collected from 112 sampling plots where the abundance, height, basal diameter, and crown diameter for the A. lechuguilla plants were measured. Sites were grouped into three site index categories (low, medium, and high) using the Importance Value Index (IVI). Afterward a classical discriminant analysis (CDA) was applied to derive linear functions capable of classifying new sites into these predefined categories. Statistical assumptions of multivariate normality, homogeneity of covariance matrices, and low multicollinearity were met. The discriminant functions showed high classification accuracy (95.54%), with full correct classification of low and high site index categories. Additional validation through MANOVA and principal component analysis (PCA) confirmed the separation of groups and the ecological coherence of the selected variables. This approach provides a simple, practical, and replicable model for assessing shrubland site quality using field measurable features. It also offers a tool for sustainable harvesting and conservation of A. lechuguilla. Full article

This study investigated the influence of process parameters on the recovery of phenolic compounds and antioxidant activity from pineapple peel using green extraction technologies: ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE). A two-level factorial design was used to evaluate the effects of the solvent-to-solid ratio, time, temperature, ethanol concentration, and power on the yield of hydrolyzable and condensed polyphenols. The extracts were characterized using HPLC-MS, and their antioxidant activity was assessed using DPPH, ABTS, and FRAP assays. UAE yielded the highest condensed polyphenol content (323.82 mg/g), while MAE extracts demonstrated superior antioxidant activity (FRAP: 90.40 mgEqTrolox/g). The predominant compound identified using both methods was 1-caffeoylquinic acid. The most influential variable in UAE was the solvent-to-solid ratio, whereas extraction time was the most significant variable in MAE. These findings highlight the potential of pineapple peel valorization through sustainable extraction methods, with UAE favoring phenolic yield and MAE enhancing bioactivity, thereby supporting their application in the food and nutraceutical industries. Full article

The increasing demand for food necessitates that agri-food systems adopt innovative techniques to enhance food production while optimizing the use of limited resources, such as water. In agriculture, hydrogels are being increasingly used to enhance water retention and reduce irrigation requirements. However, most of these materials are based on synthetic polymers that are not biodegradable. This raises serious environmental and health concerns, highlighting the urgent need for sustainable, biodegradable alternatives. Biomass-derived from agro-industrial waste presents a substantial potential for producing hydrogels, which can effectively function as water collectors and suppliers for crops. This review article provides a comprehensive overview of recent advancements in the application of agro-industrial waste for the formulation of hydrogels. Additionally, it offers a critical analysis of the development of hydrogels utilizing natural and compostable materials. Agro-industrial and food waste, which are rich in hemicellulose and cellulose, have been utilized to enhance the mechanical properties and water absorption capacity of hydrogels. These biomaterials hold significant potential for the development of effective hydrogels in agricultural applications; they can be either hybrid or natural materials that exhibit efficacy in enhancing seed germination, improving water retention capabilities, and facilitating the controlled release of fertilizers. Natural hydrogels derived from agro-industrial waste present a sustainable technological alternative that is environmentally benign. Full article

Thermal analysis (TA) has been a valuable tool for controlling the carbon equivalent (CE) of cast irons. Additionally, this technique can provide enhanced control over melt quality, allowing for the avoidance of defects such as undesirable graphite morphology and the formation of carbides. To obtain the most valuable information from the TA, it is necessary to minimize the variations in the filling operation of the TA cups. However, the mass and pouring temperature of TA cups can vary in TA’s typical foundry operations. A design of experiments was performed to determine whether specific parameters of cooling curves used for quality control can distinguish the inoculation effect in the melt when the mass and the pouring temperature of TA cups are varied. The minimum temperature of the eutectic arrest proved to be a robust inoculation potential control parameter when variations in the cup’s mass were within a range of 268–390 g and were filled at any pouring temperature between 1235 and 1369 °C. Lighter cups under 268 g and poured at a low temperature are not suitable for controlling inoculation potential by TA; however, they remain helpful in controlling CE. These later cups are related to cooling times of less than 180 s, which can serve as a criterion for discarding unsuitable samples. A bimodal population of cell surfaces was revealed in the samples, with the population of small cells being proportionally more numerous in samples with lower TE_min values. Full article

Background: Cognitive decline is a growing public health concern in Latin America, driven by rapid aging, widespread micronutrient inadequacies, and socioeconomic disparities. Despite the recognized importance of nutrition, many older adults struggle to meet daily dietary micronutrients requirements, increasing the risk of mild cognitive impairment (MCI). This study aimed to establish expert consensus on the role of Multivitamin and Mineral supplements (MVMs) in promoting cognitive healthy aging among older adults in Latin America. Methods: A panel of nine experts in geriatrics, neurology, and nutrition applied a modified Delphi methodology to generate consensus statements. The panel reviewed the literature, engaged in expert discussions, and used structured voting to develop consensus statements. Results: Consensus was reached on 14 statements. Experts agreed that cognitive aging in Latin America is influenced by neurobiological, lifestyle, and socioeconomic factors, including widespread micronutrient inadequacies (vitamins B-complex, C, D, E, and minerals such as zinc, magnesium, chromium, copper, iron and selenium), which were identified as critical for global cognitive function and brain structures, yet commonly inadequate in the elderly. While a balanced diet remains essential, MVMs can be recommended as a complementary strategy to bridge nutritional gaps. Supporting evidence, including the COSMOS-Mind trials, demonstrate that MVM use improves memory and global cognition, and reduces cognitive aging by up to 2 years in older adults. Conclusions: MVMs offer a promising, accessible adjunct for cognitive healthy aging in Latin America’s elderly population, particularly where dietary challenges persist. Region-specific guidelines, public health initiatives, and targeted research are warranted to optimize outcomes and reduce health inequities. Full article

Vermicomposting is a sustainable biotechnological process that transforms organic waste through the synergistic activity of earthworms, such as Eisenia fetida, and their associated microbiota. This study evaluated bacterial and physicochemical dynamics during the vermicomposting of bovine manure by analyzing the microbial composition of the substrate and the gut of E. fetida at three time points (weeks 0, 6, and 12). The V3–V4 region of the 16S rRNA gene was sequenced, and microbial diversity was characterized using QIIME2. Significant differences in alpha diversity (observed features, Shannon index, and phylogenetic diversity) and beta diversity indicated active microbial succession. Proteobacteria, Bacteroidota, and Actinobacteriota were the dominant phyla, with abundances varying across habitats and over time. A significant enrichment of Proteobacteria, Bacteroidota, and the genera Chryseolinea, Flavobacterium, and Sphingomonas was observed in the manure treatments. In contrast, Actinobacteriota, Firmicutes, and the genera Methylobacter, Brevibacillus, Enhygromyxa, and Bacillus, among others, were distinctive of the gut samples and contributed to their dissimilarity from the manure treatments. Simultaneously, the physicochemical parameters indicated progressive substrate stabilization and nutrient enrichment. Notably, the organic matter and total organic carbon contents decreased (from 79.47% to 47.80% and from 46.10% to 27.73%, respectively), whereas the total nitrogen content increased (from 1.70% to 2.23%); these effects reduced the C/N ratio, which is a recognized indicator of maturity, from 27.13 to 12.40. The macronutrient contents also increased, with final values of 1.41% for phosphorus, 1.50% for potassium, 0.89% for magnesium, and 2.81% for calcium. These results demonstrate that vermicomposting modifies microbial communities and enhances substrate quality, supporting its use as a biofertilizer for sustainable agriculture, soil restoration, and agrochemical reduction. Full article

The synthesis of bioplastics from renewable resources is essential for green living. PHBV (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) is a biodegradable and biocompatible material ideal for various industrial applications. The impact of levulinic (LA), valeric acids (VA), and sodium propionate (SPr) as co-substrates in biomass and the synthesis of 3-hydroxy valerate (3HV) and co-polymerization of PHBV by Burkholderia thailandensis E264 (BtE264) was assessed. Thermogravimetric, XRD, NMR, and mechanical characterization were performed on the homopolymer (PHB) and co-polymer (PHBV), and compared to the PHBV-STD. BtE264 produced the co-polymer PHBV when adding any of the three co-substrates. LA showed a higher positive effect on microbial growth (8.4 g∙L⁻¹) and PHBV production (3.91 g∙L⁻¹), representing 78 and 22 mol % of 3HB and 3HV, respectively. The PHBV obtained with LA had a melting temperature (Tm) lower than the PHB homopolymer and presented lower values for melting enthalpies (ΔHf); the degree of crystallization and TGA values indicated that PHBV had better thermal stability. Additionally, FTIR and NMR revealed that BtE264 synthesizes PHBV with an organization in monomeric units (3HB-3HV), suggesting differentiated incorporation of the monomers, improving 3.4 times the break elongation the co-polymer’s tensile properties. This study highlights the co-substrates’ relevance in PHBV synthesis using BtE264 for the first time. Full article

Biotechnological valorization of Flourensia cernua foliage was carried out using fungal solid-state fermentation; several outcomes of this bioprocess were identified which added value to the plant material. F. cernua leaves placed in aluminum trays were inoculated with Aspergillus niger; extracts of this plant were evaluated and the foliage was tested for in vitro digestibility. The solid bioprocess was carried out at 75% humidity for 120 h and after the fermentation, β-glucosidase activity; phenolics and in vitro digestibility were quantified and measured. Two high β-glucosidase production levels were detected at 42 and 84 h with 3192 and 4092 U/L, respectively. Several phenolics of industrial importance were detected with a HPLC-ESI-MS, such as glycosides of luteolin and apigenin. The other outcome was a substantial improvement in anaerobic digestibility. The unfermented sample registered a 30% in vitro degradability, whereas samples subjected to 84 h of fungal fermentation increased degradability by up to 51%. This bioprocess was designed to detect more than one product, which can contribute to an increase in the added value of F. cernua foliage. Full article

Tomato crops are treated with high concentrations of synthetic fertilizers and insecticides to increase yields, but the careless use of these chemicals harms the environment and human health and affects plant pathogen resistance. The effect of foliar spray of three concentrations of chitosan (500, 1000, and 2000 mg L⁻¹) on plant growth, yield, fruit quality, and physiological performance in two tomato varieties (Floradade and Candela F1) was studied. Physiological traits such as photosynthesis, chlorophyll content, and leaf area index of the plants were positively affected by chitosan, an effective compound that biostimulates growth, with increases in biomass of organs with respect to the control treatment. Chitosan also improved tomato quality, such as increases in polyphenols, antioxidant capacity, flavonoids, carotenoids, vitamin C, and total soluble solids in both tomato varieties. Finally, yield increased by 76.4% and 65.4% in Floradade and Candela F1, respectively. The responses of tomato plants to chitosan application were different depending on the variety evaluated, indicating a differential response to the biostimulant. The use of chitosan in agriculture is a tool that has no negative effects on plants and the environment and can increase the productive capacity of tomato plants. Full article

Although favorable effects of Selenium nanoparticles (SeNPs or nSe) in tomato have been reported, research has concentrated on stress alleviation and disease management. From the above it is noticeable that the effect of NPs varies greatly depending on the model plant, nanoparticle (concentration, size, shape), and application (foliar or drenching). For this reason, the objective of this study was to investigate the impact of biostimulating tomato plants under no stressor conditions (Solanum lycopersicum cv. ‘Pomodoro’ L.) with SeNPs on morpho-physiological and fruit quality parameters. Three doses of Selenium nanoparticles (5, 15, and 30 mg L⁻¹), and a control were applied via a foliar application after transplanting. The results indicate that a 5 mg L⁻¹ SeNP treatment improved the growth and yield of the tomato, with the exception of the root length and leaf weight. Moreover, all doses modified the evaluated physiology, bioactive compounds, and fruit quality parameters. This research helped in understanding the SeNPs’ effect on tomato plants in greenhouses under a no stressor condition. Full article

Precipitation-hardenable stainless steels (PHSS) are widely used in various applications in the aeronautical industry such in as landing gear supports, actuators, and fasteners, among others. This research aims to study the pitting corrosion behavior of passivated martensitic precipitation-hardening stainless steel, which underwent passivation for 120 min at 25 °C and 50 °C in citric and nitric acid baths before being immersed in solutions containing 1 wt.% sulfuric acid (H₂SO₄) and 5 wt.% sodium chloride (NaCl). Electrochemical characterization was realized employing electrochemical noise (EN), while microstructural analysis employed scanning electron microscopy (SEM). The result indicates that EN reflects localized pitting corrosion mechanisms. Samples exposed to H₂SO₄ revealed activation–passivation behavior, whereas those immersed in NaCl exhibited pseudo-passivation, indicative of an unstable oxide film. Current densities in both solutions ranged from 10⁻³ to 10⁻⁵ mA/cm², confirming susceptibility to localized pitting corrosion in all test conditions. The susceptibility to localized attack is associated with the generation of secondary oxides on the surface. Full article

A parallel bacterial foraging algorithm was developed for the multiple sequence alignment problem. Four sets of homologous genetic and protein sequences related to Alzheimer’s disease among various species were collected from the NCBI database for convergence analysis and performance comparison. The main question was the following: is the bacterial foraging algorithm suitable for the multiple sequence alignment problem? Three versions of the algorithm were contrasted by performing a t-test and Mann–Whitney test based on the results of a 30-run scheme, focusing on fitness, execution time, and the number of function evaluations as performance metrics. Additionally, we conducted a performance comparison of the developed algorithm with the well-known Genetic Algorithm. The results demonstrated the consistent efficiency of the bacterial foraging algorithm, while the version of the algorithm based on gap deletion presented an increased number of function evaluations and excessive execution time. Overall, the first version of the developed algorithm was found to outperform the second version, based on its efficiency. Finally, we found that the third bacterial foraging algorithm version outperformed the Genetic Algorithm in the third phase of the experiment. The sequence sets, the algorithm’s Python 3.12 code and pseudocode, the data collected from the executions, and a GIF animation of the convergence on various different sets are available for download. Full article