Search Results (24)

This research focuses on synthesizing novel tetrahydroquinoline–1,2,3-triazole hybrids as potential agents for neurodegenerative diseases, particularly Alzheimer’s disease (AD). The series of structurally distinct hybrid compounds synthesized in this study has not been previously reported in the literature. The synthetic strategy involved a diastereoselective imino Diels–Alder reaction (Povarov reaction) to construct the tetrahydroquinoline (THQ) core, where various catalysts, including phthalic acid, Lewis acids, KSF (montmorillonite), and ceric ammonium nitrate (CAN), were screened. Phthalic acid was selected as the most efficient catalyst for this crucial step. Following this, we employed efficient click chemistry to introduce the triazole moiety, adhering to green chemistry principles throughout the process. The chemical structure of the synthetized compounds was assigned using an analysis of Nuclear Magnetic Resonance (NMR), Mass Spectrometry (MS), and Infrared (IR) spectroscopy. Furthermore, in silico analyses performed with Swiss ADME and OSIRIS Property Explorer indicated that most compounds exhibited excellent drug-like characteristics and favorable pharmacokinetic profiles. The synthesized compounds were evaluated as inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) using the modified Ellman methodology. The inhibitory activity is presented as IC₅₀ values for each enzyme and compared to galantamine as a reference standard. These findings offer promising directions for the development of new therapeutic agents for AD based on organic synthesis. Full article

The widespread but often poorly regulated use of pesticides has triggered urgent debates on their hidden effects beyond resistance in target pests. This study investigates the morphological effects of pesticide exposure, specifically the organophosphate chlorpyrifos, using geometric morphometrics to assess fluctuating asymmetry (FA) in wing shapes of houseflies. Developmental stability (DS), the capacity of an organism to maintain an optimal phenotype under stress, serves as a key indicator of environmental and genetic stress. Flies collected from pesticide-exposed areas in rural areas in Chile (Arbolillo) exhibited significantly higher wing asymmetry than those from less exposed zones, reflecting developmental disturbances caused by chlorpyrifos. These findings emphasize the potential of FA as a biomarker for pesticide-related environmental stress. By linking pesticide exposure to measurable phenotypic disruption, this study calls for urgent integration of morphometric and genomic tools to better understand resistance mechanisms, while also promoting sustainable pest management practices. Our findings demonstrate that even a common insect like the housefly can serve as a biological sentinel, warning of broader ecological and public health risks in pesticide-dominated landscapes. Full article

Shiga toxin-producing Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) are E. coli pathovars of particular relevance to infant health. While the intestinal tract of humans and animals constitutes their primary habitat, these bacteria can also persist in natural environments such as sand. The aim of this study was to evaluate the persistence of STEC and EPEC strains in sand microcosms under controlled conditions of heat and desiccation in order to estimate their viability in this matrix and provide evidence regarding the potential risks associated with the use of sandboxes in public spaces. The study included STEC strains belonging to clinically important serotypes (O26:H11, O103:H2, O111:H8, O121:H19, O145:NM, O157:H7 and O174:H28), animal-derived EPEC strains, and a non-pathogenic E. coli strain (NCTC 12900). The strains were inoculated into sterile sand microcosms and maintained at 37 °C. Death curves, persistence in the matrix, presence of virulence genes, and ability to produce biofilm were evaluated. The death and persistence curves varied by serotype; some strains remained viable in the viable but non-culturable state for extended periods. All strains retained their virulence-associated genetic markers throughout the assays. None of the STEC strains was classified as a biofilm producer under the experimental conditions, whereas the two EPEC strains were identified as weak and moderate biofilm producers. However, no association was found between biofilm formation and persistence in the matrix. The findings provide an initial approach and provide relevant evidence of the capacity of STEC and EPEC strains to survive in sand, which could represent a potential risk in recreational environments. Full article

Within the area of study of neurodegenerative diseases, particularly Alzheimer’s disease (AD), this research focused on the synthesis and evaluation of novel tetrahydroquinoline (THQ) derivatives with potential antioxidant activity. The toluidine N-propargylation synthesis protocol was optimized, achieving a significant increase in yield by using sodium carbonate and reaction temperature variation. Subsequently, four THQ compounds with alkene variation were successfully synthesized, including some which had not been previously reported in the literature. The synthesized compounds were characterized by nuclear magnetic resonance (NMR), mass spectrometry, and infrared spectroscopy (IR), which confirmed their structures and purity. In silico analyses performed with SwissADME and OSIRIS Property Explorer indicated that most of the compounds exhibited excellent drug-like characteristics and favorable pharmacokinetic profiles. Antioxidant evaluation was performed using DPPH and ABTS assays, in which all compounds demonstrated excellent antioxidant capacity, with EC50 values below 10 μg/mL in the ABTS assay, significantly outperforming the ascorbic acid control (EC50 = 35 μg/mL). The results suggest that the predominant radical-scavenging mechanism is single electron transfer (SET). This study provides a solid foundation for further investigations into the potential of THQs’ derivatives as antioxidants, and potential cholinesterase inhibitors in the context of neurodegenerative diseases such as Alzheimer’s. As a future projection, an enzymatic evaluation, including regarding mechanisms of action and the exploration of a hybrid synthesis of THQ/triazole, is proposed based on these promising results. Full article

Many scientific articles have been written about management students’ perceptions of corporate social responsibility. Most of these investigations were carried out on small samples, made up of students from a single university. Very few investigations have compared students from different universities and countries. The main objective of this paper is to investigate whether students’ countries operate as an explanatory variable for their perceptions of this concept. Fifty-four previous articles were reviewed, identifying some important conceptual problems and a high amount of methodological diversity. The second objective of this paper is to describe and analyze these problems and methodologies, with the aim of contributing to the development of this field of research. A sample of 1992 undergraduate students in management courses who were studying at 18 universities located in three countries (Colombia, Ecuador and Peru) was selected. A definition of corporate social responsibility was adopted. This concept was operationalized through a set of 18 indicators. An exploratory factor analysis showed that these indicators operationalize the main dimensions of social responsibility. It was found that there are statistically significant differences between the perceptions of the students from the 18 universities, but when comparing universities from the same country, these differences disappear. In addition, it was found that the relationship between perception and country is independent of gender, age, work experience and the degree that students are pursuing. This work contributes to our current knowledge in this field of study, because it shows that the university environment of each country operates as an explanatory variable for students’ perceptions of social responsibility. Also, this work contributes to the design of appropriate methodological strategies for carrying out comparative studies on the perceptions of social responsibility, both locally and internationally. Full article

Background and Objectives: The Ventilatory Workload Kinetic Index (VWKI) has been proposed as a clinical instrument to evaluate ventilatory balance–imbalance. However, the regulated application of scales that allow an integral evaluation of the object of study and their subsequent reliability evaluation should be continuous. The objective was to determine the reliability of the VWKI between two evaluators and its applicability in the clinical field of physiotherapy. Materials and Methods: The methodology was divided into three stages: (i) induction period, (ii) application of the VWKI, and (iii) assessment of reliability. Results: The VWKI total score obtained excellent inter-rater reliability (ICC = 0.913, p < 0.05). The airway resistance (AR) showed moderate inter-rater reliability (ICC = 0.528, p < 0.05), while the use of accessory musculature (UAM) showed poor inter-rater reliability (ICC = 0.483, p < 0.05). In the physiotherapy care prioritization system, for both evaluator A (EA) and evaluator B (EB), the total VWKI score was significantly higher in priority 1 (p = 0.001; p < 0.05, respectively). Regarding the total VWKI score by services, it was observed that both EA and EB rated the VWKI significantly higher in the intensive care unit (ICU) than in medicine and the other services (p = 0.001, p = 0.0001 and p < 0.05, p < 0.05, respectively). Conclusions: VWKI is highly reliable in the total score. It is also consistent with the system of prioritization of physiotherapy care and the ability to determine the severity of clinical respiratory symptoms. Full article

Reusing the by-products from wood pulp processing can promote the efficient use of resources. In this sense, the objective of this research was to determine the agronomic efficiency of CaCO₃ and Na₂SO₄ by-products from wood pulp processing to establish criteria for their use and avoid undesirable side effects when applying these materials to the soil. Six treatments in proportions of 1; 0.9; 0.75; 0.5, 0.25, and 0, of CaCO₃/Na₂SO₄, respectively, were incubated at a constant temperature and humidity for 15 days. The first proportion consisted of 100% CaCO₃, while M1 mixed 90% CaCO₃ and 10% Na₂SO₄, M2: 75% CaCO₃ and 25% Na₂SO₄, M3: 50% CaCO₃ and 50% Na₂SO₄, M4: 25% CaCO₃ and 75% Na₂SO₄, with the last proportion comprised of 100% Na₂SO₄. Samples of 40 g from two soil series, Licantén (Inceptisol) and San José (Andisol), were used. The rates applied for each treatment were 0, 1, 2, 4, and 8 g of material per kg of dry soil. At the end of the incubation period, pH in water, pH in CaCl₂, exchange bases (Ca²⁺, Mg²⁺, K⁺ and Na⁺) and extractable sulfur were determined. The results showed that the San José soil had a pH buffering capacity three times higher than that of the Licantén soil. The linear increase in pH was thus explained by the soil type in relation to the applied rate of CaCO₃. The analysis of the increase in the exchangeable Na percentage (ESP) showed that the soils increased up to about 70% of their ESP with the highest added rate of Na₂SO₄. The application of a mixture of 25% Na₂SO₄ and 75% CaCO₃ resulted in an increase in the ESP close to 15%; therefore, it is not recommended to use mixtures with a Na₂SO₄ content higher than 25% in these soils. Finally, we affirm that for M2 the maximum recommended dose for application should be 4 Mg ha⁻¹, i.e., 3 g of material per kg of soil. Full article

Agricultural soils account for about 60% of the global atmospheric emissions of the potent greenhouse gas nitrous oxide (N₂O). One of the main processes producing N₂O is denitrification, which occurs under oxygen-limiting conditions when carbon is readily available. On grazed pastures, urine patches create ideal conditions for denitrification, especially in soils with high organic matter content, like Andisols. This lab study looks at the effects of Urine-urea-N load on the Andisol potential to emit N₂O. For this, we investigated the effects of three levels of urea-N concentrations in cow urine on emissions of N₂O, N₂, and CO₂ under controlled conditions optimised for denitrification to occur. Results show total N₂O emissions increased with increasing urine-N concentration and indicate that denitrification was the main N₂O-producing process during the first 2–3 days after urine application, though it was most likely soil native N rather than urine-N being utilised at this stage. An increase in soil nitrate indicates that a second peak of N₂O emissions was most likely due to the nitrification of ammonium hydrolysed from the added urine, showing that nitrification and denitrification have the potential to play a big part in N losses and greenhouse gas production from these soils. Full article

To assess ventilatory evolution through the Ventilatory Workload Kinetic Index (VWKI) in patients with asthma and chronic obstructive pulmonary disease (COPD) during stability and exacerbation. Retrospective analysis. Conducted at the Padre Alberto Hurtado Hospital, Santiago, Chile. Ten patients with asthma and fifty-five with COPD participated. Sixty-five clinical records were reviewed. The VWKI in stability and exacerbation of these patients was extracted. When analyzing the baseline with the peak in both asthma and COPD, there was a significant increase in the VWKI. Similarly, the loads, translations, and supports significantly increased from the baseline to the peak. However, in the loads, there were no changes in airway resistance for asthma or in cough for COPD. Likewise, the supports for asthma and COPD showed no changes in the O₂. The VWKI determined ventilatory issues in outpatients and made locating the greatest compromise in loads, translations, or supports possible. Full article

The cultivar selection and nitrogen (N) fertilization are key management factors to improve potato yield. The aim of the present study was to evaluate the ecophysiological determinants of biomass and tuber yield in potato genotypes in response to N availability under field conditions. Experiments 1 and 2 were carried out in a volcanic soil of southern Chile during the 2021–2022 season. Treatments were applied in the factorial combination of (i) fifteen genotypes of potatoes and (ii) three N fertilization rates (0, 200 and 400 kg N ha⁻¹, 0 N, 200 N and 400 N, respectively). A wide range in total dry matter biomass (5.9–22.1 Mg DM ha⁻¹) and tuber yield (5.1–18.3 Mg DM ha⁻¹) was observed across the experiments. In both experiments, the total biomass and tuber yield were affected by the N rate (p < 0.05) and genotype (p < 0.01), but not by their interaction (p > 0.05). Tuber dry matter yield was strongly related (R² = 0.94, p < 0.01) to total biomass and weakly related to the harvest index (HI). In both experiments, the total biomass was explained by the radiation use efficiency (RUE) (R² = 0.69–0.75, p < 0.01). The principal components analysis showed that tuber yield, biomass and RUE were related. The Finlay and Wilkinson analysis revealed that different cultivars varied significantly (p < 0.001) in their sensitivity to N availability. Across environments (3 N rates × 2 experiments), the most responsive cultivars to N availability were Pukara, Rodeo, Asterix and Patagonia. This information will be useful for potato production systems aimed at improving tuber yield and N use efficiency. Full article

Urea present in cattle urine contributes large amounts of nitrogen (N) to grazed pastures, which can be the equivalent to approximately 1000 kg N ha⁻¹. However, there are no studies in volcanic soils of southern Chile on the effect of different concentrations of urinary N deposited in the soil, nor of the effect different wetting and drying conditions mimicking the variation in weather conditions on the nitrification process from urea to NH₄⁺ and total oxidized nitrogen (TON) over time. In addition, the inhibition of nitrification driven by the accumulation of NH₃ at high rates of N applied to Andisol has not been evaluated. Fresh cattle urine was applied at three different rates of N equivalent to 247 kg N ha⁻¹ (Low N), 461 kg N ha⁻¹ (Medium N), and 921 kg N ha⁻¹ (High N), as well as deionized water as a control. Further, three moisture conditions were imposed: constant moisture (CM), drying–rewetting (DRW) cycles at 7-day intervals, and soil drying (SD). Destructive soil core samples were evaluated for top and bottom halves individually every 7 days over a 36-day period to measure changes on inorganic N and pH. There were no interaction effects for N rates and soil moisture. The main effect of the different rates of N on mineralization was significant throughout the incubation period, while the effect of the different moisture conditions was variable over time. High N was associated with elevated NH₃ concentrations and could explain why total N mineralization was partially inhibited. These results suggest that the presence of different nitrifying microorganisms in soil under different chemical and physical conditions determines nitrification, and thus, the oxidation of ammonia should be studied in more detail as the first step of nitrification, specifically in volcanic soils. Full article

Atmospheric cold plasma (ACP) is a non-thermal technology whose ability to inactivate pathogenic microorganisms gives it great potential for use in the food industry as an alternative to traditional thermal methods. Multiple investigations have been reviewed in which the cold plasma is generated through a dielectric barrier discharge (DBD) type reactor, using the atmosphere of the food packaging as the working gas. The results are grouped into meats, fruits and vegetables, dairy and lastly cereals. Microbial decontamination is due to the action of the reactive species generated, which diffuse into the treated food. In some cases, the treatment has a negative impact on the quality. Before industrializing its use, alterations in colour, flavour and lipid oxidation, among others, must be reduced. Furthermore, scaling discharges up to larger regions without compromising the plasma homogeneity is still a significant difficulty. The combination of DBD with other non-thermal technologies (ultrasound, chemical compounds, magnetic field) improved both the safety and the quality of food products. DBD efficacy depends on both technological parameters (input power, gas composition and treatment time) and food intrinsic properties (surface roughness, moisture content and chemistry). Full article

Cow urine is a rich source of mobile nutrients such as nitrate (NO₃⁻) and potassium (K⁺). The aim of this experiment was to evaluate the wetting pattern distribution through soil profile of cow urine patch in an andisol. Two field experiments across two consecutive years were carried out to compare cow urine patches in relation to initial wetting pattern and volume of soil affected. Bromide (Br⁻) has successfully been used as an inert hydrologic tracer to indicate the movement of NO₃⁻ and K⁺ in soil–water systems. The distribution of Br⁻ (used as a urine tracer) on the soil surface and down the profile was irregular in all the patches. Cow urine patches covered a surface area of 0.27 and 0.35 m², respectively, and penetrated to a depth of 70 cm. The rapid downward movement of urine occurred through macropore flow but even so, between 27% and 40% of the applied Br⁻ was detected in the 0–5 cm soil layer. Br⁻ showed concentrations greater than 1500 mg kg⁻¹ and up to 3000 mg kg⁻¹, and as the concentration of Br⁻ decreases, the frequency and depth of affected layers increases. Despite the differences in moisture and in the distribution of the Br⁻ concentration in both years, the concentration frequency of 500 to 1500 mg kg⁻¹ represented around 37% of the affected volume of soil (bulb of urine) in both years. Up to 40% of the bulb represented N equivalent rates between 187 and 975 kg N ha⁻¹. These values can potentially be emitted in gases such as NH₃, N₂O, and N₂. It is suggested that the presence of N in the volume of affected soil could vary due to the moisture content of the soil, and that in andisols of southern Chile under permanent grasslands there are a large number of macropores that would induce preferential flows. Full article

The objective of this study was to assess N dynamics in the soil, and the response in regard to dry matter yield (DM yield; kg·DM·ha⁻¹), N yield (g·N·m⁻²) and N concentration (g·N·kg⁻¹ DM) under urine patches and dung pats and in the affected zone of the grassland soil over 304 days. The amount of N under the urine and dung patches increased until day 10 and then started to decrease until the end of the experiment, reaching control treatment levels. The DM yield in the urine patch zone and the 0–10 cm zone around the dung pat was higher than in the control treatment throughout the evaluated period, while in the 0–30 cm zone around the urine patch and the 10–20 cm zone around the dung pat the DM yield was negatively affected by the application of excreta. The maximum accumulated N yield was up to two times higher than the control in the 0–10 cm zone of the dung pat, while the mean concentration of N throughout the period was 42% higher than the control for the “urine patch” zone and 47% higher in the 0–10 cm area around the dung pat. The total absorbed N was 19% and 15% for urine and dung excreta, respectively. Further research is needed to explain the variables that might affect the results obtained, and it is necessary to evaluate the botanical composition as a factor that contributes to this effect. Full article

HLA-DRB1 shared epitope (SE) alleles are important genetic contributors for the risk of developing anti-citrullinated protein antibodies (ACPA)-positive rheumatoid arthritis (RA), particularly in Caucasians. We aimed to analyze the contribution of HLA-DRB1 alleles and single nucleotide polymorphisms (SNPs) within the major histocompatibility complex (MHC) region to the susceptibility to develop ACPA-positive RA in a Latin American (LA) population with admixed ancestry. A total of 289 ACPA-positive RA patients and 510 controls were enrolled in this study. The presence of HLA-DRB1*04:01, *09:01 and *10:01 was increased in ACPA-positive RA patients compared with healthy controls (p < 0.0001, p < 0.001 and p < 0.01, respectively), whereas DRB1*07:01 and *08:02 was associated with a decreased risk of ACPA-positive RA (p < 0.001 and p < 0.01, respectively). These results showed a strong correlation with estimates from studies in Asians but not in Caucasian populations. The present study describes the protective effects of the HLA-DRB1*07:01 and *08:02 alleles in ACPA-positive RA patients in a LA population for the first time. Identifying relationships between HLA-DRB1 alleles and RA is important for identifying disease associations in different ethnic groups in order to reach a better understanding of RA worldwide. Full article