Search Results (1,244)

Although it is the wettest continent, droughts are a regular occurrence in South America. As the effects of anthropogenic influences, including climate change, become more pronounced, droughts are expected to increase in frequency and severity. The purpose of this study is to assess the relative drought vulnerability of the countries in South America. Each country is evaluated for drought exposure, sensitivity, adaptive capacity, and overall vulnerability. Sixteen drought-related indicators were used to measure the relative vulnerability of each country and to measure separate scores for exposure, sensitivity, and adaptive capacity to identify what factor(s) contributed to a country’s vulnerability. The results indicate that Ecuador, a country with a high population and limited water resources, is the most vulnerable to drought in South America, followed by Colombia and Uruguay. Conversely, the country least vulnerable to drought is Guyana, followed by Suriname and Chile. Our analysis suggests that there are both geographic and as well as economic factors influencing the relative drought vulnerability of countries in South America. Full article

We present a dynamical systems approach to modeling nonlinear flood dynamics using 20 years of water level data from Durazno, Uruguay. Flood events are identified, and their periodicity and temporal distribution are analyzed in relation to rain gauge precipitation. Phase space reconstruction enables data-driven neural network modeling and quantification of the relationship between water level and soil moisture. Bifurcation diagrams define basin-specific flood thresholds, offering a mechanistic framework for improved flood forecasting and risk assessment. Full article

Climate extremes threaten the resilience of Eucalyptus plantations, yet hybridization with drought-tolerant species may enhance stress tolerance. This study analyzed xylem anatomical and functional drought responses in commercial Eucalyptus grandis (GG) clones and hybrids: E. grandis × camaldulensis (GC), E. grandis × tereticornis (GT), and E. grandis × urophylla (GU1, GU2). We evaluated vessel traits (water transport), fibers (mechanical support), and wood density (D) in stems and branches. Theoretical stem hydraulic conductivity (k_Stheo), vessel lumen fraction (F), vessel composition (S), and associations with previous hydraulic and growth data were assessed. While general drought responses occurred, GC had the most distinct xylem profile. This may explain it having the highest performance in different irrigation conditions. Red gum hybrids (GC, GT) maintained k_Stheo under drought, with stable F and a narrower vessel size, especially in branches. Conversely, GG and GU2 reduced F and S; and stem k_Stheo declined for a similar F in these clones, indicating vascular reconfiguration aligning the stem with the branch xylem. Almost all clones increased D under drought in any organ, with the highest increase in red gum hybrids. These results reveal diverse anatomical adjustments to drought among clones, partially explaining their growth responses. Full article

The search for natural sources of bioactive compounds with health-promoting properties has intensified in recent years. Among these, Tannat grape pomace (TGP), a primary byproduct of winemaking, stands out for its high phenolic content, although its bioactivity may be affected during gastrointestinal digestion. This study aimed to evaluate the impact of in vitro digestion on the antioxidant (ABTS, ORAC-FL, intracellular ROS inhibition), anti-diabetic (α-glucosidase inhibition), anti-obesity (lipase inhibition), and anti-inflammatory (NO inhibition) properties of five sugar-free biscuits formulated with varying percentages of TGP and sucralose. No significant differences were observed in the bioaccessible fractions (BFs, representing the compounds potentially released in the small intestine) between control biscuits and those enriched with TGP, suggesting limited release of phenolics at this stage. Conversely, the colonic fractions (CFs, simulating the material reaching the colon) from biscuits with higher TGP content exhibited greater bioactivities. HPLC-DAD-MS analysis of the CF from the biscuit containing 20% TGP and 4% sucralose revealed a high content of procyanidin trimers, indicating the persistence of these specific phenolic compounds after in vitro digestion. These findings suggest that TGP-enriched biscuits may deliver health benefits at the colonic level and support their potential application in the formulation of functional foods. Further microbiota and in vivo studies should be assessed to confirm the latter. Full article

A novel model of the electrical demand of a power system capable of representing the hourly power load and its dependence on temperature is presented. The application of the model to the Colombian system is described with an evaluation of the error obtained. For the simulation of the optimal operation of systems with high renewable energy participation, a model such as the one presented is of vital importance in order to take into account the dependence of demand on meteorological variables. It is also necessary for the simulation of the expected effects of climate change on electricity demand. Full article

Falkland Islands English (FIE) began its development in the first half of the 19th century. In part, as a consequence of its youth, FIE is an understudied variety. It shares some morphosyntactic features with other anglophone countries in the Southern Hemisphere, but it also shares lexical features with regional varieties of Spanish, including Rioplatense Spanish. Che is one of many South American words that have entered FIE through Spanish, with its spelling ranging from “chay” and “chey” to “ché”. The word has received some marginal attention in terms of its meaning. It is said to be used in a similar way to the British dear or love and the Australian mate, and it has been compared to chum or pal, and is taken as an equivalent of the River Plate, hey!, hi!, or I say!. In this work, we explore the hypothesis that che entered FIE through historical contact with Rioplatense Spanish, drawing on both linguistic and sociohistorical evidence, and presenting survey, corpus, and ethnographic data that illustrate its current vitality, usage, and social meanings among FIE speakers. In situ observations, fieldwork, and an online survey were used to look into the vitality of che. Concomitantly, by crawling social media and the local press, enough data was gathered to build a small corpus to further study its vitality. A thorough literature review was conducted to hypothesise about the borrowing process involving its entry into FIE. The findings confirm that the word is primarily a vocative, it is commonly used, and it is indicative of a sense of belonging to the Falklands community. Although there is no consensus on the origin of che in the River Plate region, it seems to be the case that it entered FIE during the intense Spanish–English contact that took place during the second half of the 19th century. Full article

Remote sensing tools have been proposed to assist with rice crop monitoring but have been developed and validated on ponded rice. This two-year study was conducted on a commercial rice farm with irrigation automation technology aimed to (i) understand how canopy reflectance differs between high-yielding ponded and aerobic rice, (ii) validate the feasibility of using the squared simplified canopy chlorophyll content index (SCCCI²) for N uptake estimates, and (iii) explore the SCCCI² and similar chlorophyll-sensitive indices for grain quality monitoring. Multispectral images were collected from an unmanned aerial vehicle during both rice-growing seasons. Above-ground biomass and nitrogen (N) uptake were measured at panicle initiation (PI). The performance of single-vegetation-index models in estimating rice N uptake, as previously published, was assessed. Yield and grain quality were determined at harvest. Results showed that canopy reflectance in the visible and near-infrared regions differed between aerobic and ponded rice early in the growing season. Chlorophyll-sensitive indices showed lower values in aerobic rice than in the ponded rice at PI, despite having similar yields at harvest. The SCCCI² model (RMSE = 20.52, Bias = −6.21 Kg N ha⁻¹, and MAPE = 11.95%) outperformed other models assessed. The SCCCI², squared normalized difference red edge index, and chlorophyll green index correlated at PI with the percentage of cracked grain, immature grain, and quality score, suggesting that grain milling quality parameters could be associated with N uptake at PI. This study highlights canopy reflectance differences between high-yielding aerobic (averaging 15 Mg ha⁻¹) and ponded rice at key phenological stages and confirms the validity of a single-vegetation-index model based on the SCCCI² for N uptake estimates in ponded and non-ponded rice crops. Full article

Vaccine adjuvants are non-immunogenic agents that enhance or modulate immune responses to co-administered antigens and are essential to modern vaccines. Despite their importance, few are approved for human use. The rise of new pathogens and limited efficacy of some existing vaccines underscore the need for more advanced and effective formulations, particularly for vulnerable populations. Aluminum-based adjuvants are commonly used in vaccines and effectively promote humoral immunity. However, they mainly induce a Th2-biased response, making them suboptimal for diseases requiring cell-mediated immunity. In contrast, saponin-based adjuvants from the Quillajaceae family elicit a more balanced Th1/Th2 response and generate antigen-specific cytotoxic T cells (CTL). Due to ecological damage and limited availability caused by overharvesting Quillaja saponaria Molina barks, efforts have intensified to identify alternative plant-derived saponins with enhanced efficacy and lower toxicity. Quillaja brasiliensis (A.St.-Hil. and Tul.) Mart. (syn. Quillaja lancifolia D.Don), a related species native to South America, is considered a promising renewable source of Quillajaceae saponins. In this review, we highlight recent advances in vaccine adjuvant research, with a particular focus on saponins extracted from Q. brasiliensis leaves as a sustainable alternative to Q. saponaria saponins. These saponin fractions are structurally and functionally comparable, exhibiting similar adjuvant activity when they were formulated with different viral antigens. An alternative application involves formulating saponins into nanoparticles known as ISCOMs (immune-stimulating complexes) or ISCOM-matrices. These formulations significantly reduce hemolytic activity while preserving strong immunoadjuvant properties. Therefore, research advances using saponin-based adjuvants (SBA) derived from Q. brasiliensis and their incorporation into new vaccine platforms may represent a viable and sustainable solution for the development of more less reactogenic, safer, and effective vaccines, especially for diseases that require a robust cellular immunity. Full article

Phytochemicals are a potential alternative to antibiotic growth promoters. This study evaluated the effects of phytochemicals (curcuminoids, trans-cinnamaldehyde, and piperine) and monensin on performance and ruminal fermentation during the transition period in grazing dairy cows. In a complete randomized design, 60 Holstein cows (36 multiparous, 24 primiparous; 9 fistulated) were assigned to (1) control (CTL), (2) monensin (MON, 0.30 g/cow/day), or (3) phytochemicals (PHY, 50 g/cow/day) treatment from 30 days prepartum to 60 days postpartum. Prepartum, cows received a total mixed ration (TMR); postpartum, they grazed between a.m. and p.m. milking and were supplemented with TMR. Ruminal fermentation was evaluated at −7, 30, and 60 days postpartum. Prepartum dry matter intake was lower in MON primiparous cows than in CTL and PHY. Additives increased milk yield and lactose percentage in primiparous cows. PHY cows had lower acetate, higher propionate, and reduced acetate-to-propionate and ketogenic-to-glucogenic ratios at 60 days postpartum. MON reduced prepartum protozoa, while PHY increased prepartum branched-chain volatile fatty acids (BCVFAs). Both additives decreased BCVFA and protozoa postpartum. Additives reduced ammonia at 30 days, but only PHY persisted at 60 days. MON and PHY improved primiparous performance, enhanced ruminal fermentation, and promoted glucogenic fermentation while reducing ammonia and protozoa. Full article

This study developed an Energy Quadrilemma Index (EQI) for Latin American countries, analyzing data from six countries from 2014 to 2020. Using the Principal Component Analysis method, this work reduced the dimensionality of 20 indicators grouped into four dimensions: energy security, energy equity, sustainable development, and a new social context axis. The results reveal significant disparities among the countries in the study. For example, Uruguay shows robust indicators, Paraguay exhibits low utilization of the energy it produces, and Chile displays the poorest results in the sustainable development axis. Many countries’ widespread dependence on hydroelectricity makes them vulnerable to water crises. The results show that social, economic, and structural inequalities represent the main barriers to the energy transition, often marginalizing low-income populations. Ensuring a fair and inclusive transition requires implementing targeted policies and solutions adapted to each country’s specific context. Although Costa Rica leads in performance, it faces significant challenges in the field of sustainability. In contrast, Honduras has made some progress with sustainable development but still demonstrates weaknesses in other areas. These results highlight that standardized solutions can exacerbate regional inequalities, demanding approaches more tailored to local needs. This work’s novelty lies in the use of the social context dimension as a feature to assess energy poverty in selected countries. Full article

A simple and fast analytical method was developed and applied to assess the effect of two forms of zinc fertilization on a pecan tree cultivar in Uruguay: fertigation and foliar application with a specially formulated fertilizer. Zinc content was determined in 36 leaf samples from two crop cycles: 2020–2021 and 2021–2022. Fresh samples were dried, ground, and sieved. Analytical determinations were performed by flame atomic absorption spectrometry (FAAS, considered a standard method) and energy dispersive X-ray spectrometry (EDXRF, the proposed method). In the first case, sample preparation was carried out by microwave-assisted digestion using 4.5 mol L⁻¹ HNO₃. In the second case, pellets (Φ 13 mm, 2–3 mm thick) were prepared by direct mechanical pressing. Figures of merit of both methodologies were adequate for the purpose of zinc monitoring. The results obtained from both methodologies were statistically compared and found to be equivalent (95% confidence level). Based on the principles of Green Analytical Chemistry, both procedures were evaluated using the Analytical Greenness Metric Approach (AGREE and AGREEprep) tools. It was concluded that EDXRF was notably greener than FAAS and can be postulated as an alternative to the standard method. The information emerging from the analyses aided decision-making at the agronomic level. Full article

The high water demand of rice cultivation is mainly due to flood irrigation, which requires large volumes not only to meet evapotranspiration needs, but also due to losses from percolation, lateral seepage, and surface runoff. In addition to lowering water use efficiency, surface runoff may transport nutrients. This study aimed to calibrate and validate a daily water balance model to estimate surface runoff losses across three rice-growing seasons. During the first two seasons, different model components were calibrated by comparing simulated and observed water depths. In the final season, the calibrated model was validated using direct runoff measurements obtained from weirs and flowmeters. Results showed strong agreement between model estimates and direct measurements of water depth and surface runoff. Linear regression models showed good fit, with coefficients of determination (R²) above 0.80 for water depth and 0.79 for runoff. A validated daily water balance model, combined with periodic monitoring of water depth, proved to be a reliable tool for estimating surface runoff during the rice-growing season. Total runoff—from irrigation, rainfall, and final drainage—represented between 7.5% and 18% of the total water input. This approach offers a practical tool for improving irrigation water management and understanding runoff-driven nutrient transport. Full article

Background/Objectives: Climate change is a major factor exacerbating non-communicable diseases (NCDs) such as cardiovascular diseases, neoplasms, respiratory diseases, and diabetes, especially in vulnerable Latin American regions. This study analyzes the impact of environmental exposures related to climate change on the NCD burden in eight Latin American countries by quantifying the disability-adjusted life years (DALYs) attributable to these factors. Using Global Burden of Disease (GBD) data (1990–2021), we performed multiple linear regression to assess associations between DALYs and environmental risk factors—air pollution (particulate matter, nitrogen dioxide), radon, lead, and extreme temperatures—in Argentina, Brazil, Chile, Colombia, Costa Rica, Mexico, Peru, and Uruguay. The study included major NCDs, and the population was stratified by age and sex. Results: Ischemic heart disease was the leading cause of DALYs in most countries. Particulate matter pollution was the main environmental risk factor contributing to the NCD burden, mainly affecting cardiovascular and respiratory diseases. Mexico showed the highest DALYs from particulate and ozone pollution; temperature and lead exposure also contributed in some countries. Nitrogen dioxide was the primary risk factor for asthma. Statistically significant relationships between environmental factors and DALYs were confirmed. Conclusions: Climate change-related exposures significantly increase the burden of NCDs in Latin America. Targeted interventions in industry, transportation, and energy, along with sustainable urban policies, are essential to mitigate health impacts and reduce disparities. Integrating environmental health into public policies can improve health outcomes amid ongoing climate challenges. Full article

The shelf life of minimally processed fresh (MPF) pears is affected by raw material characteristics and production factors. This study evaluated the effect of raw material storage (3 months in regular atmosphere [RA], 3 and 6 months in controlled atmosphere [CA]) on the organoleptic and functional quality of MPF pears packaged in polypropylene (PP) and low-density polyethylene (LDPE) for 0, 10, and 15 days at 0 °C. Wedges from 3-month CA showed the lowest respiratory activity (about 8.31 mg CO₂ kg⁻¹ h⁻¹), and those from 6-mounth CA maintained higher firmness after 15 days. Lightness decreased during storage, less so in harvest samples, which also showed less browning. Nevertheless, polyphenol oxidase (PPO) activity increased fivefold after 15 days. Total polyphenol content decreased by about 50% during storage. Wedges in PP packaging exhibited higher total antioxidant capacity (TAC) measured by DPPH than those in LDPE (15.55 and 13.77 mg EAA 100 g⁻¹ FW, respectively). In both, the contents were reduced after 15 days (15–38%). No differences in TAC were observed in the FRAP assay, where values remained unchanged. Significant correlations between PPO activity, TAC, and color variables suggest ongoing oxidative processes. In contrast to the effect of raw material storage, the type of packaging did not significantly affect any of the measured variables. Full article

Background: Traditional sandblasted large-grit acid-etched (SLA) surface treatments frequently utilize alumina (Al₂O₃) blasting, which may leave residual particles embedded in implant surfaces, potentially compromising biocompatibility and osseointegration. This study investigates a contamination-free alternative: titanium dioxide particle (TiO₂) blasting followed by hydrochloric acid (HCl) etching, aimed at generating a cleaner, hierarchical micro–nano-textured surface. Methods: Grade IV titanium disks were treated either with TiO₂ sandblasting alone or with an additional HCl etching step. Surfaces were analyzed via atomic force microscopy (AFM), scanning electron microscopy (SEM), contact angle measurements, and profilometry. hFOB osteoblasts were cultured to assess adhesion, proliferation, metabolic activity, and morphology. Results: The combination treatment produced a more homogeneous micro–nano structure with significantly increased roughness and a cleaner surface chemistry. Osteoblast proliferation and metabolic activity were notably improved in the TiO₂ and HCl group. SEM imaging showed a more organized cytoskeletal structure and pronounced filopodia at 72 h. Conclusions: Titanium blasting combined with HCl etching yields a cost-effective, contamination-free surface modification with promising early-stage cellular responses. This approach represents a safer and effective alternative to conventional SLA treatment. Full article