Universidad de Magallanes
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Dynamic response of the performance and emissions of an LPG diesel dual-fuel engine with water injection
No full textThis paper evaluated the dynamic response of the compression ignition engine's performance parameters and emissions when water was injected into the intake manifold at different water ratios. This technique effectively decreased NOx emissions and mitigated knock intensity when the engine ran at dual fuel mode. With a WR = 143 %, NOx emissions were reduced by 52 % at 100 % diesel operation, whereas with a WR = 132 %, NOx emissions were reduced by 57 % at dual fuel mode operation. The knock intensity decreased from 1.52 V to 1.12 V using a water ratio of 133 % when the engine operated with a substitution of diesel by LPG of 50 % on a mass basis. The results also revealed that water injection increased HC emissions from 220 +/- 1 ppm to 430 +/- 1 ppm, whereas the Particle Matter (PM2.5) increased from 42.4 mu g/kWh to 127.3 mu g/kWh at 100 % diesel operation. When the engine operated at dual fuel mode PM2.5 increased from 42.4 mu g/kWh to 84.3 mu g/kWh. Finally, two First Order plus Dead Time models were deduced through the system identification technique to simulate the dynamic response of Knock Intensity when a step change of water ratio was made. These models play a key role in tuning system controllers for knock suppression
Adiponectin and resistin modulate the progression of Alzheimer's disease in a metabolic syndrome model
No full textMetabolic syndrome (MetS), a cluster of metabolic conditions that include obesity, hyperlipidemia, and insulin resistance, increases the risk of several aging-related brain diseases, including Alzheimer's disease (AD). However, the underlying mechanism explaining the link between MetS and brain function is poorly understood. Among the possible mediators are several adipose-derived secreted molecules called adipokines, including adiponectin (ApN) and resistin, which have been shown to regulate brain function by modulating several metabolic processes. To investigate the impact of adipokines on MetS, we employed a diet-induced model to induce the various complications associated with MetS. For this purpose, we administered a high-fat diet (HFD) to both WT and APP/PSN1 mice at a pre-symptomatic disease stage. Our data showed that MetS causes a fast decline in cognitive performance and stimulates A beta(42) production in the brain. Interestingly, ApN treatment restored glucose metabolism and improved cognitive functions by 50% while decreasing the A beta(42/40) ratio by approximately 65%. In contrast, resistin exacerbated Ab pathology, increased oxidative stress, and strongly reduced glucose metabolism. Together, our data demonstrate that ApN and resistin alterations could further contribute to AD pathology
Late glacial climate evolution in the Patagonian Andes (44-47° S) from alpine glacier modelling
No full textNumerical glacier models applied to moraine chronologies provide an opportunity to quantify past climate change. Here we apply a two-dimensional coupled mass balance -ice flow model to well-dated moraine sequences deposited by former alpine glaciers at two central Patagonian sites: Cerro Rinon (43.97 degrees S, 71.64 degrees W) and Rio Tranquilo (47.50 degrees S, 72.38 degrees W), to reconstruct the local temperatures during both the Antarctic Cold Reversal (14.7-13 ka) and the Younger Dryas (12.9-11 ka). Modelled tempera-ture anomalies during the Antarctic Cold Reversal are-2.6 +/- 0.4 degrees C at 44 degrees S, and-2.9 +/- 0.6 degrees C at 47 degrees S. At both locations this cold event is followed by temperature increases of +0.6-0.7 degrees C or precipitation re-ductions of c. 20% to drive glacier retreat to moraines deposited during Younger Dryas time. The consistent climatic anomalies between these two latitudes suggest this region of Patagonia was responding to a common climatic event. Further, the late-glacial temperature anomalies found here compare well to those determined by similar glacier modelling techniques in New Zealand, at 43-44 degrees S. These results support a trans-Pacific response throughout the southern mid to high latitudes (43-47 degrees S) during the ACR that is best explained by a northward expansion of the south westerly winds.(c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Harmful algal blooms in Patagonian fjords and channels systems: Recent advances, gaps, and priorities in a changing ocean
No full textA simple and low-cost open dynamic chamber for the versatile determination of methane emissions from aquatic surfaces
No full textMethane (CH4) emissions from aquatic ecosystems require accurate monitoring in the context of climate change. Among the several methods for CH4 flux measurement, open dynamic chambers (ODC) are a reliable option. This method consists of a floating chamber through which a carrier gas is constantly flowing, providing accurate flux measurement with high temporal resolution. However, this method requires expensive and heavy CH4 analyzers with high sensitivity, as well as a carrier gas system that comprises a gas cylinder and a gas flow controller, among other components. This system involves significant weight and cost challenges, limiting method implementation in certain settings and hindering its wider adoption. To address these limitations, we developed a simplified ODC configuration using atmospheric air as the carrier gas and a light and relatively less expensive detector. We applied this method to a 450-ha urban lake with CH4 emissions ranging from moderate diffusive to high ebullitive fluxes. Concurrent measurements using a high-sensitivity CH4 analyzer allowed us to compare the accuracy of the simplified ODC method and to assess its advantages and disadvantages. Results show that our method provides accurate CH4 flux measurements with a spatial resolution comparable to high-sensitivity analyzers. This offers a more cost-effective, straightforward, and lightweight alternative to high-sensitivity detectors and carrier gas systems, simplifying ODC deployment in aquatic ecosystems
Impact of polyethylene microplastics and copper nanoparticles: Responses of soil microbiological properties and strawberry growth
No full textMicroplastics (MPs) can act as vectors of contaminants such as fungicides and trace metals. Their presence in water or soil might affect fruits and vegetables, while interactions between MPs and copper (Cu) nanoparticles might pose greater risks to soil properties, plant development and yield. The objective of this study was to evaluate the effect of the presence of MPs and Cu nanoparticles on plant growth and yield of strawberry, as well as on soil microbiological properties. The experiment was carried out in pots in a greenhouse; the soil was contaminated with polyethylene MPs and Cu nanoparticles. The design was completely randomized with four treatments (control, MPs, Cu, and Cu + MPs). Six months after planting, significant changes were observed in terms of plant height, stem diameter and root surface area. When compared to the control treatment, the MPs treatment resulted in a 27 % decrease in plant height, lower stem diameter values in all the contaminant treatments, and decreases in root surface area by 20 %, 21 % and 17 % in the MPs, Cu, and Cu + MPs treatments, respectively. Regarding number of inflorescences, total number of fruits, fruit weight and total aerial biomass, the MPs, Cu, and Cu + MPs treatments were statistically lower than the control (p < 0.05). The soil dehydrogenase activity decreased by 30 % due to the combined application of MPs and Cu nanoparticles, but this was not observed when MPs or Cu nanoparticles were applied alone, evidencing possible effects on the biological activity of the soil. Significant differences were found in acid phosphatase and urease activities in the Cu treatments with respect to the control and MPs treatments except for soil respiration. It can be concluded that the presence of Cu nanoparticles combined with polyethylene MPs favored a greater Cu availability in the soil and root Cu accumulation of strawberry plants
Effectiveness of elastic band training and group-based dance on physical-functional performance in older women with sarcopenia: a pilot study
No full textBackground Sarcopenia is a syndrome associated with aging that causes progressive loss of skeletal muscle mass and muscle function. In this pilot study, we compared the effectiveness of elastic band training regarding group-based dance on fat mass, fat-free mass, handgrip strength (HGS; dominant and non-dominant hand), leg strength, timed up-and-go (TUG) and walking speed in older women with sarcopenia.Methods This is a randomized controlled trial, single-blind, repeated measures of parallel groups (elastic band group: EBG, n = 21; group-based dance: GBD, n = 19), and a quantitative methodology. Three 60-minute sessions per week for 12 weeks were dedicated to the interventions with pre- and post-assessments. A two-factor mixed analysis of variance (ANOVA) model with repeated measures was performed to measure the groupxtime effect.Results A significant interaction revealed for fat-free mass (F-1,F-16= 18.91; p < 0.001; EBG + 10.9% vs. GBD - 1.97%), HGS dominant hand (F-1,F-16= 7.44; p = 0.014; EBG + 10.9% vs. GBD + 0.59%), HGS non-dominant hand (F1,16= 6.41; p = 0.022; EBG + 10.21% vs. GBD + 3.80%), leg strength (F1,16= 17.98; p < 0.001; EBG + 9.1% vs. GBD + 3.83%), TUG (F1,16= 7.52; p = 0.014; EBG - 14.7% vs. GBD - 1.0%) and walking speed (F1,16 = 6.40; p = 0.019; EBG - 7.6% vs. GBD - 4.35%) in favor of EBG.Conclusion Elastic band training produces significantly greater responses on physical-functional performance regarding group-based dance in older women with sarcopenia. On the other hand, the EBG revealed a significant improvement in fat-free mass and upper and lower limb muscle strength, as well as a significant decrease time in TUG, and walking speed. Elastic band exercise is a safe, easy, affordable, and effective physical activity strategy, according to the findings
pSESYNTH project: Community mobilization for a multidisciplinary paleo database of the Global South
No full textHow to enhance paleoscientific research, collaboration and application in the Global South? The INQUA-funded multi-year pSESYNTH project envisions the first multi-disciplinary Holocene paleo database through a collaborative vision for past human–environmental systems in the Global South, and their future sustainability
Decoupled Control for Double-T Dc-Dc MMC Topology for MT-HVdc/MVdc Grids
No full textFeatured Application The control method proposed in this work can be applied to power converters operating in multi-terminal high-voltage dc systems. This paper proposes a decoupled control of a dc-dc modular multilevel converter (MMC) based on a double-T topology intended for multi-terminal high voltage direct current (MT-HVdc) transmission systems or emerging distribution systems operating in medium voltage direct current (MVdc). The aim of the proposed control strategy is to obtain an input current with reduced harmonic content and to eliminate the output ac common-mode voltage, which is not allowed in MT-HVdc systems. The control strategy consists of injecting two circulating ac currents and two dc currents that allow the energy balance between the arms of the converter and the general energy balance of the topology. The dc and ac currents are decoupled and allow control over load variations and reference changes in the dc-links. The proposed topology is mathematically modeled and the control method is then derived. Simulation results are presented to validate the proposed system
Evaluating population histories in Patagonia and Tierra del Fuego, Chile, using ancient mitochondrial and Y-chromosomal DNA
No full textObjectives: This study aims to characterize the genetic histories of ancient hunter-gatherer groups in Fuego-Patagonia (Chile) with distinct Marine, Terrestrial, and Mixed Economy subsistence strategies. Mitochondrial (mtDNA) and Y-chromosome data were generated to test three hypotheses. H-0: All individuals were drawn from the same panmictic population; H-1: Terrestrial groups first populated the region and gave rise to highly specialized Marine groups by similar to 7,500 cal BP; or H-2: Marine and Terrestrial groups represent distinct ancestral lineages who migrated independently into the region. Methods: Ancient DNA was extracted from the teeth of 50 Fuegian-Patagonian individuals dating from 6,895 cal BP to after European arrival, and analyzed alongside other individuals from previous studies. Individuals were assigned to Marine, Terrestrial, and Mixed Economy groups based on archeological context and stable isotope diet inferences, and mtDNA (HVR1/2) and Y-chromosome variation was analyzed. Results: Endogenous aDNA was obtained from 49/50 (98%) individuals. Haplotype diversities, F-ST comparisons, and exact tests of population differentiation showed that Marine groups were significantly different from Terrestrial groups based on mtDNA (p < 0.05). No statistically significant differences were found between Terrestrial and Mixed Economy groups. Demographic simulations support models in which Marine groups diverged from the others by similar to 14,000 cal BP. Y-chromosome results showed similar patterns but were not statistically significant due to small sample sizes and allelic dropout. Discussion: These results support the hypothesis that Marine and Terrestrial economic groups represent distinct ancestral lineages who diverged during the time populations were expanding in the Americas, and may represent independent migrations into Fuego-Patagonia