Universidad Católica del Maule
Recent publications
Delay discounting refers to the depreciation of the value of a reward as a function of the time it takes to obtain it. Growing evidence shows altered delay discounting in several pathological conditions, including neurological disorders. Here, we conducted a systematic review and meta-analysis of the published literature on delay discounting (DD) in Parkinson’s Disease (PD). We found steeper DD in patients with PD, compared to healthy controls, both in “on” and “off” dopaminergic medication. This pattern was unaffected by the presence of impulse control disorders. Moreover, we found steeper DD in “on medication” compared to “off medication” condition. These results confirm altered DD in PD and suggest an independent influence of the dopaminergic medication and the clinical condition itself on it.
The study of nanoparticles (NPs) and their application in different areas of research, including biomedicine, is attracting the attention of researchers worldwide. Numerous investigations published during the last 20 years cover the fabrication of new materials in the nanoscale, and several uses have been proposed. Metallic nanoparticles (MNPs) have generated a high level of interest, based on improved optical, electrical and magnetic properties, ease of manufacturing, small sizes, and easy functionalization. However, when it comes to Biomedicine, particle aggregation, possible toxicity, and the need for effective cell internalization, still demand active investigation. The main strategy to overcome these drawbacks is possibly the use of capping agents to increase the stability of the particles in dispersion, their biocompatibility and functionalization. In this review, important concepts and characteristics of MNPs, are collected and described. The importance of surface coating for biomedical applications of metallic nanoparticles as well as the most used capping agents and metallic nanomaterials, are also discussed. Finally, the text includes examples and essential characteristics for the biomedical use of MNPs, including the consideration of important challenges. Aspects such as relevant biological activity, increased biocompatibility and functionalization potential are among the most desirable attributes of a capping agent. Capping agents are essential to overcome biocompatibility, particle internalization by cells and the stability of metallic nanoparticles (MNPs) in dispersion. This review deals with the modification of MNPs with surfactants to obtain improved nanomaterials for biomedical applications. The text includes several examples from the scientific literature and is a guide in the use of MNPs for biomedical purposes.
Due to the unique characteristics of composite materials, the study of composite beams is far more complex than the study of homogeneous beams. The finite element method has proven to be a powerful approach to analyze composites subjected to the most distinctive situations. In the present work, two element solutions using cubic polynomials are considered: with continuous stresses and with discontinuous stresses along the transverse direction. Both converge to the analytical solution as the number of elements increase, i.e. with a finer mesh. Besides satisfying the boundary conditions at the surfaces and interfaces, the first solution gives better outcomes close to the center of the beam. On the other hand, the second solution gives better outcomes close to the borders of the beam, but it has a larger number of nodal parameters. The results are compared to a zig-zag element solution which has a number of nodal parameters independent of the number of layers. An element based on the Reissner mixed variational theorem is also included for additional comparisons. It is concluded that the cubic polynomials used to expand the cross section functions, must be different in each layer in order to achieve a reasonable agreement between the analytical and the calculated transverse normal stress.
Bitter pit (BP) is one of the most relevant post-harvest disorders for apple industry worldwide, which is often related to calcium (Ca) deficiency at the calyx end of the fruit. Its occurrence takes place along with an imbalance with other minerals, such as potassium (K). Although the K/Ca ratio is considered a valuable indicator of BP, a high variability in the levels of these elements occurs within the fruit, between fruits of the same plant, and between plants and orchards. Prediction systems based on the content of elements in fruit have a high variability because they are determined in samples composed of various fruits. With X-ray fluorescence (XRF) spectrometry, it is possible to characterize non-destructively the signal intensity for several mineral elements at a given position in individual fruit and thus, the complete signal of the mineral composition can be used to perform a predictive model to determine the incidence of bitter pit. Therefore, it was hypothesized that using a multivariate modeling approach, other elements beyond the K and Ca could be found that could improve the current clutter prediction capability. Two studies were carried out: on the first one an experiment was conducted to determine the K/Ca and the whole spectrum using XRF of a balanced sample of affected and non-affected ‘Granny Smith’ apples. On the second study apples of three cultivars (‘Granny Smith’, ‘Brookfield’ and ‘Fuji’), were harvested from two commercial orchards to evaluate the use of XRF to predict BP. With data from the first study a multivariate classification system was trained (balanced database of healthy and BP fruit, consisting in 176 from each group) and then the model was applied on the second study to fruit from two orchards with a history of BP. Results show that when dimensionality reduction was performed on the XRF spectra (1.5 - 8 KeV) of ‘Granny Smith’ apples, comparing fruit with and without BP, along with K and Ca, four other elements (i.e., Cl, Si, P, and S) were found to be deterministic. However, the PCA revealed that the classification between samples (BP vs. non-BP fruit) was not possible by univariate analysis (individual elements or the K/Ca ratio).Therefore, a multivariate classification approach was applied, and the classification measures (sensitivity, specificity, and balanced precision) of the PLS-DA models for all cultivars evaluated (‘Granny Smith’, ‘Fuji’ and ‘Brookfield’) on the full training samples and with both validation procedures (Venetian and Monte Carlo), ranged from 0.76 to 0.92. The results of this work indicate that using this technology at the individual fruit level is essential to understand the factors that determine this disorder and can improve BP prediction of intact fruit.
Background Fear is one of the basic emotions generated during periods of infectious diseases. Therefore, the aim of this study was to develop and validate a scale that assesses monkeypox fear, the Monkeypox Fear Scale (MFS). Methods A total of 451 Peruvians participated (61% women and 39% men), with a mean age of 28.31 years (SD = 9.72). based on procedures from classical test theory (CTT) and item response theory (IRT). Classical Test Theory (CTT) and Item Response Theory (IRT) procedures were used. Results The results showed that MFS has a two-factor structure related to emotional and physiological fear factors (χ2 = 41.87; df = 12; p < .001; CFI = .99; TLI = .99; RMSEA = .074 [IC90% .051–.100]). In addition, the physiological and emotional factors showed good reliability. Measurement invariance analysis showed that the factor structure of the MFS is strictly invariant between male and female groups. Finally, the discrimination and difficulty parameters of the items show adequacy. In addition, the scale seems to be more accurate in measuring high levels of fear of monkeypox. Conclusion The MFS has adequate psychometric evidence to assess fear of monkeypox in the Peruvian population. These findings may guide future studies related to the consequences of monkeypox on mental health.
The metal carbonyl clusters have been recognized as one of the most successful organometallic complexes with extensive catalytic applications. In this paper, we carried out a DFT study of the stability, electronic structure and thermodynamic properties of the intermediates [M3(CO)11] and [M3(CO)10] in the synthesis of [M3(2,3-bpp)(CO)10] (M=Ru and Os). CO binding energy analysis revealed that [M3(CO)10(μ-CO)], [Ru3(CO)8(μ-CO)2] and [Os3(CO)6(μ3-CO)2(μ-CO)2] are the most stables compounds due to the presence of bridge carbonyls which favor a covalent interaction. Sigma donation from the carbonyl to metal d orbital is the most significant contribution. Moreover, spectroscopic and computational studies indicated that [Ru3(2,3-bpp)(CO)10] is in good agreement with the analogues osmium complex. Regarding the pathway associated to the formation of [M3(2,3-bpp)(CO)10] we have found that the determinant step is the dissociation of a second CO axial into [M3(CO)10(μ-CO)]. Thus, unsaturated metal carbonyl intermediates exert a thermodynamic and kinetically control as consequence of the orbital reorganization.
Various environmental alterations resulting from the current global change compromise the persistence of species in their habitual environment. To cope with the obvious risk of extinction, plastic responses provide organisms with rapid acclimatization to new environments. The premise of plastic rescue has been theoretically studied from mathematical models in both deterministic and stochastic environments, focusing on analyzing the persistence and stability of the populations. Here, we evaluate this premise in the framework of a consumer-resource interaction considering the energy investment towards reproduction vs. maintenance as a plastic trait according to positive/negative variation of the available resource. A basic consumer-resource mathematical model is formulated based on the principle of biomass conversion that incorporates the energy allocation toward vital functions of the life-cycle of consumer individuals. Our mathematical approach is based on the impulsive differential equations at fixed moments considering two impulsive effects associated with the instants at which consumers obtain environmental information and when energy allocation strategy change occurs. From a preliminary analysis of the non-plastic temporal dynamics, namely when the energy allocation is constant over time and without experiencing changes concerning the variation of resources, both the persistence and stability of the consumer-resource dynamic are dependent on the energy allocation strategies belonging to a set termed stability range. We found that the plastic energy allocation can promote a stable dynamical pattern in the consumer-resource interaction depending on both the magnitude of the energy allocation change and the time lag between environmental sensibility instants and when the expression of the plastic trait occurs.
Atmospheric longwave downward radiation (Ld) is one of the significant components of net radiation (Rn), and it drives several essential ecosystem processes. Ld can be estimated with simple empirical methods using atmospheric emissivity (εa) submodels. In this study, eight εa global models were evaluated, and the one with the best performance was calibrated on a global scale using a parametric instability analysis approach. Climatic data were obtained from a dynamically consistent scale resolution of basic atmospheric quantities and computed parameters known as NCEP/NCAR reanalysis (NNR) data. The model's goodness of fit was evaluated with monthly average values of the NNR data. The εa Brutsaert model resulted in the best performance, and then it was calibrated. The seasonal global trend of Brutsaert’s εa equation calibrated coefficient ranged between 1.2 and 1.4, and five homogeneous zones with similar behavior (clusters) were found with the K-means analysis. Finally, the calibrated Brutsaert’s εa equation improved the Rn estimation, with an error reduction, at the worldwide scale, of 64%. Meanwhile, the error reduction for every cluster ranged from 18 to 77%. Hence, Brutsaert’s equation coefficient should not be considered a constant value for use in εa estimation, nor in time nor space.
Chemical structures of selective blockers of TASK channels contain aromatic groups and amide bonds. Using this rationale, we designed and synthesized a series of compounds based on 3-benzamidobenzoic acid. These compounds block TASK-1 channels by binding to the central cavity. The most active compound is 3-benzoylamino-N-(2-ethyl-phenyl)-benzamide or F3, blocking TASK-1 with an IC50 of 148 nM, showing a reduced inhibition of TASK-3 channels and not a significant effect on different K+ channels. We identified putative F3-binding sites in the TASK-1 channel by molecular modeling studies. Mutation of seven residues to A (I118A, L122A, F125A, Q126A, L232A, I235A, and L239A) markedly decreased the F3-induced inhibition of TASK-1 channels, consistent with the molecular modeling predictions. F3 blocks cell proliferation and viability in the MCF-7 cancer cell line but not in TASK-1 knockdown MCF-7 cells, indicating that it is acting in TASK-1 channels. These results indicated that TASK-1 is necessary to drive proliferation in the MCF-7 cancer cell line.
Chile underwent profound social changes at the end of the 19th and beginning of the 20th centuries. In this context, women began to organize themselves in public spaces to improve their living conditions in different spheres. This article analyses the contribution of Amanda Labarca to the organization of the first feminist institutions in Chile (1910-1922). It looks at this from a cultural-historical perspective to understand the implications that such women's organizations had on the country's progress at the time, drawing on both primary and secondary sources of evidence. The findings show that Labarca played a leading role in the then incipient Chilean feminist movement, as materialized by her leadership in the creation of the Círculo de Lectura in 1915. She also played an active role in various women's groups that evolved into academic, cultural, and political organizations that were consolidated between 1930-1950.
Este artículo analiza lo que nos cuentan las imágenes fotográficas en su reverso y en las huellas del verso, a través de las anotaciones, marcas o descripciones que contienen, que entregan información importante de su contexto de producción, de los sujetos u objetos fotografiados y de su trayectoria. Así, se configura un sentido apropiado de la imagen. Este artículo, pone el foco en imágenes fotográficas escolares porque representan un espacio de convivencia particular y de intercambio de experiencias que, en alguna medida, se captura y resguarda en ellas. En los pliegues, en los bordes oscurecidos o desgastados, en los márgenes marchitos y en las marcas de óxido o de otros materiales, es posible también encontrar historias, restos de memorias, afectos y rostros en un contrapunto que va más allá de la motivación del fotógrafo para captar el instante en un encuadre específico. Para el análisis, se presentan algunas imágenes fotográficas pertenecientes al archivo escolar de un centro educativo de la ciudad de Talca en la región del Maule (Chile), pues permiten develar el significado familiar, mnemónico y comunitario que estas adquieren al reunirse en ese repertorio. Este valor igualmente se desprende de la observación del material oculto en el reverso y de las marcas del verso de las imágenes fotográficas.
Background Invasive plants may displace native species. This is the case of Poa annua, the only non-native plant species successfully established in Maritime Antarctica. Nonetheless, it is uncertain which factors drive the competitive success of P. annua in the harsh environmental conditions of the region. The ability of this plant species to establish novel mutualistic interactions with resident soil fungi may be crucial for its invasiveness. Such ability may be linked to the vertical transmission of the fungal endophytes via seeds. Aims We undertook a study to assess the role of seed fungal endophytes as promoters of the establishment and invasion of Poa annua in Maritime Antarctica. Methods We explored the composition and diversity of fungal communities associated with different P. annua tissues (seeds, leaves and roots) and the soil. We also measured parameters including germination rate, above-ground biomass, reproductive structures, and the survival of invasive P. annua as well as of the native Colobanthus quitensis and Deschampsia antarctica grown from seeds with and without endophytes. Furthermore, we conducted inter- and intraspecific competition experiments among native and invasive plants, where chemically-mediated plant-to-plant interference (allelopathy) and plant growth rate were measured to calculate a relative competition index. Results We found that fungal endophyte taxa associated with P. annua tissues were very different from those in the soil. Fungal endophytes in P. annua differed among seed, root and shoot tissues, which suggests low transmission among different organs. The removal of endophytes from P. annua seeds was associated with reduced seed germination, plant growth and survivorship, while the competitive ability of P. annua (assessed by accumulated biomass) relative to native species, as well as levels of allelochemicals in soils, were higher in the presence of seed fungal endophytes. Conclusion Our results suggest that fungal endophytes, maternally inherited through seeds, improve host fitness and may contribute to the invasive success of P. annua in Antarctica.
The amount of walking for daily transport has decreased significantly over the last decades in Temuco, Chile. Moreover, the percentage of older adults (aged over 65) who did not meet the recommendations of at least 150 min of physical activity per week has increased during this time. In this regard, the present study examines the contribution of socio-demographic and built environment factors on the walking behavior of older adults in Temuco, Chile, with a view to improving their level of physical activity. A cross-sectional study was conducted among 463 older adults aged 60 years and over. Travel Diary Data taken from "Encuesta Origin Destino (EOD) 2013, Geographic information systems (GIS), audits (PEDS with certain revisions) and finally, multiple regression analysis, were used to examine the objectives. Associations were found between the walking behavior of older adults and several socio-demographic factors, as well as several built environment factors including destination (the number of parks and the land use mix), functionality (street connectivity, length of street sections and off-street parking lots) and aesthetics (views of nature, building height, and articulation in building design). These findings should be considered by urban/transport policymakers to improve the walking behavior of older adults in this city.
High-entropy alloys (HEAs) display outstanding mechanical properties which make possible new technological applications. There are many studies of bulk HEAs, but here we focus on FeCrNiCuCo single-crystal face-centered cubic (FCC) samples with 40% and 50% nanoscale porosity, where the pores constrain plasticity. In order to disentangle the role of chemical complexity during deformation, we compare HEA samples to Average Atom (AA) samples with the same average properties as the HEA, but where all atoms are equivalent. Elastic modulus and plastic yielding are much higher than expected from Au nanofoam scaling predictions. We find that HEA and AA materials behave similarly to each other and to other FCC nanoporous samples until the point where failure begins. Deformation produces mostly partial dislocations that move and leave behind stacking faults crossing filaments, with sessile dislocations and some dislocation tangles forming due to the large plastic strain. Differences in sample failure modify the evolution of void and ligament size distributions. The AA sample presents ductile necking and ductile fracture of a few filaments, as in other single element FCC nanoporous samples. Failure in the HEA sample not only includes some ductile filaments fracture, but also brittle fracture of the filaments due to localized shear, which causes plane slippage, as identified by machine learning methods. Therefore, chemical complexity diminishes ductility in nanoporous FCC HEA samples. Graphical abstract
Implicancias etimológicas, ontológicas y epistémicas para la profesión-disciplina de las kinesiólogas y los kinesiólogos
Nanotechnology is a burning field of scientific interest for researchers in current era. Diverse plant materials are considered as potential tool in green chemistry based technologies for the synthesis of metal nanoparticles (NPs) to cope with the hazardous effects of synthetic chemicals, leading to severe abiotic climate change issues in today’s agriculture. This study aimed to determine the synthesis and characterization of metal-based nanoparticles using extracts of the selected plant Calotropis gigantea and to evaluate the enzyme-inhibition activities and antibacterial and antifungal activity of extracts of metal-based zinc nanoparticles using C. gigantea extracts. The crystal structure and surface morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). C. gigantea was examined for antimicrobial activity against clinical isolates of bacteria and fungi. The water, ethanolic, and acetone extracts of C. gigantea were studied for their antagonistic action against bacterial strains (E. coli, S. aureus, P. multocida, and B. subtilis) and selected fungal strains (A. paracistic, F. solani, A. niger, S. ferrugenium, and R. nigricans). In vitro antimicrobial activity was determined by the disc diffusion method, where C. gigantea wastested for AChE and BChE inhibitory activity using Ellman’s methodology. The kinetic analysis was performed by the proverbial Berthelot reaction for urease inhibition. The results showed that out of all the extracts tested, ethanolic and water extracts possessed zinc nanoparticles. These extracts showed the maximum zone of inhibition against F. solani and P. multocida and the lowest against S. ferrugenium and B. subtilis. A potential source of AChE inhibitors is certainly provided by the abundance of plants in nature. Numerous phyto-constituents, such as AChE and BChE inhibitors, have been reported in this communication. Water extract was active and has the potential for in vitro AChE and BChE inhibitory activity. The urease inhibition with flower extracts of C. gigantea revealed zinc nanoparticles in water extracts that competitively inhibited urease enzymes. In the case of cholinesterase enzymes, it was inferred that the water extract and zinc nanoparticles have more potential for inhibition of BChE than AChE and urease inhibition. Furthermore, zinc nanoparticles with water extract are active inthe inhibition of the bacterial strains E. coli, S. aureus, and P. multocida and the fungal strains A. paracistic, F. solani, and A. niger.
Verbal fluency tasks are frequently used in neuropsychological assessment, standing out for their easy application and good sensitivity to early cognitive impairment. However, in Argentina, the availability of updated norms is limited, especially for the action fluency variant. There is also little evidence of validity. Objectives: The aim of this study was to obtain Argentine norms for three verbal fluency tasks and to analyze their convergent validity. Methods: Using a nonprobability sampling method, 303 Argentines from a nonclinical population (age mean=66.8, 50–91 years) were recruited to participate in this study. Those with medical conditions that could compromise neuropsychological performance were excluded. Three verbal fluency tasks (i.e., phonological, semantic, and action), the Montreal Cognitive Assessment (MoCA) test, and the Digit Span-WAIS III test were administered. Correlations and multiple regressions were subsequently performed. Results: Education and age significantly explained 11.8% of the variance in phonological fluency, 15.8% of the variance in semantic fluency, and 20.2% of the variance in action fluency. Hence, the normative data varied according to educational level and age group, with normal performance limit values between 9 and 14 for phonological fluency, 11 and 18 for semantic fluency, and 8 and 17 for action fluency. Positive correlations were obtained between all verbal fluency tasks, as well as between the MoCA test and the Digit Span test. Conclusions: This study supports the applicability of three verbal fluency tasks in an Argentine context by providing age- and education-corrected norms and acceptable evidence of convergent validity.
The rhodium-catalysed ortho-selective carbenes insertion strategy to activate the non-acidic sp2 C-H bond of β-carboline and isoquinoline scaffolds was developed. This transformation endows facile fabrication of C-C bond with high atom economy, pleasant yields and wide functional group tolerance exploiting directing properties of pyridinic nitrogen. In this protocol, diazo compounds of diethyl malonate, dimethyl dimedone and oxindole are tested as carbene source with the release of environmentally benign N2 gas as the by-product. Moreover, to perceive mechanistic insights, ESI-MS studies were conducted, and the key intermediates associated with this transformation were identified. In addition, the metal-free construction of planar polycyclic indolizine-indole frameworks has been accomplished from the synthesized products. Furthermore, the neoplastic and fluorescence properties of C-N annulated compounds were also determined.
As a consequence of the megadrought in Central Chile, it is expected that most of the distribution of woody species will be narrowed in the northern limits because of restrictions imposed by soil matric potential on seed germination. In this study, we analyzed the effect of the soil matric potential on seed germination and initial recruitment of the sclerophyllous species Prosopis chilensis, Quillaja saponaria and Cryptocarya alba from contrasting geographic origins (i.e., seed sources). We evaluated the germination capacity (%) under different matric potentials (i.e., 0, −6, −33, −750 and −1250 kPa) for 100 days. Soil matric potential of −1250 kPa negatively affected the germination capacity of the three species. P. chilensis seeds stopped germinating under soil matric potential close to −1200 kPa, whereas in Q. saponaria and C. alba the complete inhibition of germination was under −1000 kPa. Seed sources also differed in their germination capacity by soil matric potential: northern seed sources of P. chilensis germinated with the lowest soil matric potential. There was no clear trend in Q. saponaria and C. alba, but in general, southern seed sources performed better than the northern ones. The results showed that Ѱm in the soil played an important role in the germinative capacity against different seed source origins, but not in soils with a north–south gradient.
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1,574 members
Antonio Roberto Zamunér
  • Departamento Kinesiología
Ileana Gonzalez
  • Laboratorio de Investigaciones Biomédicas
Armando Rojas
  • Laboratorio de Investigaciones Biomédicas
Andrés Solórzano
  • Departamento de Ciencias Biológicas y Químicas
Jorge Valenzuela
  • Departamento de Fundamentos de la Educación
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Avda. San Miguel 3605, Talca, Talca, Chile
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www.ucm.cl
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(56) (71) 2-203 100