University of the Frontier (Spanish: Universidad de La Frontera) or UFRO is a university in Temuco, Araucanía Region, Chile. It is a derivative university and part of the Chilean Traditional Universities. UFRO boasts a student body with a variety of abilities and from a variety of backgrounds, many of them are Mapuche descent..
Background Active school commuting is a relevant opportunity to increase daily physical activity among adolescents. However, participation rates remain low, particularly in middle-income countries, where structural, environmental, and social factors may interact in complex ways. Understanding these multilevel associations is essential to inform effective transport and public health strategies. Objectives To examine the associations between distance to school, perceived built environment, type of school, and active school commuting among adolescents in Chile. Methods A cross-sectional study was conducted with 200 secondary school students (mean age: 17.0 ± 0.35 years) from public, subsidized, and private schools in Talca, Chile. Active commuting was assessed via self-report and categorized as active (walking or cycling) or motorized. Distance to school was classified as <3 km or ≥3 km. Perceived built environment was measured using the ALPHA questionnaire. A binary logistic regression model was used to examine associations, adjusting for school type, sex, home-to-school distance, and the perceived built-environment dimensions retained in the final model: connectivity, home environment, and school environment. Results are presented as odds ratios (OR) with 95% confidence intervals (CI). Results The prevalence of active commuting was low (10.9% to school; 23.8% from school). Distance to school showed the strongest association with active commuting (OR = 0.44; 95% CI: 0.28–0.69; p < .001), with greater distances associated with lower likelihood of active travel. Perceived connectivity was also inversely associated with active commuting (OR = 0.71; 95% CI: 0.54–0.92; p = .011). No significant associations were found for type of school, sex, or other environmental variables. Conclusions Active school commuting among adolescents is primarily associated with structural factors, particularly distance to school, rather than individual or perceived environmental characteristics. These findings highlight the need to integrate urban planning, educational policies, and transport strategies to promote active commuting, especially in middle-income contexts characterized by spatial inequalities.
In this paper, we study thermodynamics and its applications of a family of static charged dilaton black holes in 2+1 dimensions found by Chan and Mann [Phys. Rev. D50, 6385 (1994) [Erratum-ibid. 52, 2600 (1995)]] and Xu [Eur. Phys. J. C79, 642 (2019)]. There is a dimensionless parameter N in the black hole solutions presented: It is related to the coupling constant for the dilaton with the electromagnetic field and the gravitational field. Black hole horizons exist only for 2/3 <= N<2. N=1 black hole is a solution to low-energy string theory. Thermodynamics is studied in the canonical ensemble where charge is constant as well as in grand canonical ensemble where the potential is constant. The cosmological constant is considered as a thermodynamical variable where the pressure P=-Lambda 8 pi. We computed the first law and the Smarr relations for the black hole and introduced two new thermodynamical parameters in order to satisfy the first law. We computed temperature, thermodynamic volume, specific heat capacities, Gibbs free energy and studied local and global stability of the black hole. Thermodynamic volume differs from the geometric volume. In the canonical ensemble, we noticed that thermodynamic behavior falls into two broad categories: For 23 <= N<1, small black holes are locally stable and large black holes are not. For 1 <= N<2, the black hole is locally and globally stable for all values of the horizon radius. In order to demonstrate the two broad categories, we have presented N=1,23 and N=67 black holes in detail. There were no phase transitions for the above values of N. In the grand canonical ensemble, we noticed that there is a Hawking-Page phase transition for the black hole with N=6/5. We have also studied the Joule-Thomson expansion and the Reverse Isoperimetric Inequality of these black holes. We made the observation that the charged dilaton black hole does not violate the Reverse Isoperimetric Inequality for certain values of the parameters of the theory. Finally, we have suggested future work.
Water-scarcity driven by climate change, stagnant agricultural productivity, and rapid population growth trigger food security. Sustainable alternatives such as the use of plant-growth promoting microorganisms (PGPM), including arbuscular mycorrhizal fungi (AMF), yeast (PGPY) and rhizobacteria (PGPR) offer promising sustainable solutions. However, the potential of microbial consortia remains insufficiently explored. This study aimed to evaluate the effects of synthetic microbial communities (SynComs) on the morphophysiological responses of maize, common bean, and squash under drought stress. Six microbial strains (two AMF, two PGPY and two PGPR) were combined into eight SynComs. Seeds were inoculated with AMF at germination, followed by PGPY and PGPR every 15 days after transplanting. Biomass production and leaf water potential were assessed under controlled drought conditions. Water-deficit reduced overall biomass production; yet specific SynComs, significantly enhanced plant performance. Maize and common bean inoculated with the consortium Funneliformis mosseae, Naganishia albida and Bacillus tequilensis showed increases exceeding 40
Mining tailings are waste generated continuously in large quantities and have accumulated over time, posing significant environmental challenges. This study evaluates the influence of low (MinPC) and high (MaxPC) current densities on the recovery of elements from untreated mining tailings obtained from SCM Paicav & iacute; by electrodeposition. To define both conditions, tailings were placed in containers with electrodes spaced 3-18 cm apart, and controlled currents of 1-100 mA were applied. Although MaxPC electrodes recovered a greater mass of material (1.51 g) than MinPC (0.22 g), the latter achieved higher enrichment of elements such as Ni and Mn. Under MinPC conditions, Ni exhibited the highest recovery, enrichment (19.3), and selectivity (4.8), whereas under MaxPC, the enrichment and selectivity decreased to 9.6 and 2.0, respectively. Elemental analyses (XRF, AAS, ICP-MS), together with mineralogical characterization (XRD, FT-IR, and SEM-EDS), identified quartz, pyrite, and chlorite as the main phases associated with the recovered elements. Overall, the results demonstrate that direct electrodeposition enables selective metal recovery from untreated tailings without pretreatment, chemical reagents, or additional water consumption, providing a novel and environmentally sustainable route for tailings valorization.
Abstract According to Global Cement and Concrete Association (GCCA), the cement industry is responsible for about 7–8% of all anthropogenic CO2 emissions released into the atmosphere as reported by GCCA et al. (CCUS in the Indian Cement Industry: A Review of CO2 Hubs and Storage Facilities, 2024). Clinker production results in high energy costs and the release of CO2 due to the calcination or decarbonation of its main raw material, limestone. In addition, energy is consumed to heat and maintain the temperature inside the rotary kiln, involving another significant CO2 release. This work presents a review of mitigation processes in seven Ibero-American countries (Argentina, Brazil, Chile, Colombia, Peru, Portugal and Spain) that guide the cement industry toward carbon-neutral production by 2030 and 2050. The mitigation parameters are analysed based on the global roadmap published by GCCA (Global Cement and Concrete Association), FICEM (Inter-American Cement Federation) and CEMBUREAU (European Cement Association), as well as the national roadmaps. The six main parameters identified across the countries’ roadmaps were the reduction of total direct CO2 emissions in cement production, thermal efficiency, electrical efficiency, the clinker factor, the use of alternative fuels and (re)carbonation. The adoption of biomass as an alternative fuel and the reduction of the clinker factor through the use of SCM were identified as the main strategies for lowering CO2 emissions from Portland cement production in all seven countries analysed. Despite current efforts, CO2 mitigation in the cement industry has limits. Achieving carbon neutrality by 2050 will require substantial investment in CO2 capture, storage and utilization technologies.
