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Antibacterial Films of Silver Nanoparticles Embedded into Carboxymethylcellulose/Chitosan Multilayers on Nanoporous Silicon: A Layer-by-Layer Assembly Approach Comparing Dip and Spin Coating
No full textThe design and engineering of antibacterial materials are key for preventing bacterial adherence and proliferation in biomedical and household instruments. Silver nanoparticles (AgNPs) and chitosan (CHI) are broad-spectrum antibacterial materials with different properties whose combined application is currently under optimization. This study proposes the formation of antibacterial films with AgNPs embedded in carboxymethylcellulose/chitosan multilayers by the layer-by-layer (LbL) method. The films were deposited onto nanoporous silicon (nPSi), an ideal platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. We focused on two alternative multilayer deposition processes: cyclic dip coating (CDC) and cyclic spin coating (CSC). The physicochemical properties of the films were the subject of microscopic, microstructural, and surface-interface analyses. The antibacterial activity of each film was investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria strains as model microorganisms. According to the findings, the CDC technique produced multilayer films with higher antibacterial activity for both bacteria compared to the CSC method. Bacteria adhesion inhibition was observed from only three cycles. The developed AgNPs-multilayer composite film offers advantageous antibacterial properties for biomedical applications
Seasonality in the feeding ecology of Black-necked swans (<i>Cygnus melancoryphus</i>) in a temperate wetland of southern Chile
No full textThe concomitant effects of environmental physical constraints associated with the availability and quality of food will finally affect the energy budget of wild animals. This study aimed to determine the effect of seasonality on water level, behavioural and nutritional status of Black-necked swans inhabit the Budi Lake, Chile. In winter and spring, the water level was recorded using a graduated rod and a time budget of 60 swans/hours was recorded from 8 am to 6 pm using binoculars and the focal method. In order to determine nutritional status a subset of 20 birds were captured and weight, length, wingspan, and tarsal length were measured. Also, blood sample was collected to determine cholesterol, triglycerides, and total proteins plasma concentrations. Budi Lake's water level increase in winter (111 +/- 3 cm vs 54 +/- 0.6 cm, P = 0.04). In addition, winter swan population increased significantly the time allocated to foraging at morning, and the proportion of effortful foraging behaviour (37/222 vs 14/185, P = 0.01), assigning less time to resting activities (7 +/- 4 % vs 11 +/- 2 %, P = 0.05) compared with spring population. Nutritional status was not compromised in swan populations in both seasons. In conclusion, behavioral adjustments allow Black-necked swan populations to maintain an adequate nutritional status despite the increase in water level during winter season
Mathematical Modeling and Numerical Approximation of Heat Conduction in Three-Phase-Lag Solid
No full textIn this article, we propose a mathematical model for one-dimensional heat conduction in a three-layered solid considering that an interfacial condition is present for the temperature and heat flux conditions between the layers. The numerical approach is developed by constructing a finite difference scheme to solve the initial boundary-interface problem. The numerical scheme is designed by considering the accuracy of the model on the inner part of each layer, then extending to the interfaces and boundaries by incorporating the continuous interfacial conditions. The finite difference scheme is unconditionally stable, convergent, and easy to implement since it consists of the solution of two algebraic systems. We provide three numerical examples to confirm that our numerical approximation is consistent with the analytical solution and the physical phenomenon
Sustainable coastal tourism-an overview
Get PDFAn elementary theory of sustainable coastal tourism mainly depends on the crystal clear water, healthy ecosystem, and well preserved coastal environment. Coastal tourism has drawn worldwide attention and has become extremely competitive as everybody tries to increase their profit in terms of beach visitors, both domestic and international [Joseph, and Pakkeerappa,2015]. Usually, any coastal area growth is always looked at from a business perspective, while the environmental aspect is mostly neglected. This strategy leads towards impractical beachfront development, which has different negative ramifications, on the climate and society. It is uneconomical as it destroys the actual ecological structures, such as the beach scenery, the biodiversity, and the biological system in the ocean and on the land. Also the travel industry exercise at the seaside territory destroys the beach. This study summarizes environmental impacts of coastal Tourism and the sustainable options to make it eco-friendly. The sustainable solutions were suggested for better coastal conservation. Also the study points out the future crisis pertaining to the latest Environmental Impact Assessment (EIA) 2020 by the government of India.Una teoría elemental del turismo costero sostenible depende principalmente del agua cristalina, un ecosistema saludable y un entorno costero bien conservado. El turismo costero ha atraído la atención mundial y se ha vuelto extremadamente competitivo ya quetodos intentan aumentar sus ganancias en términos de visitantes de la playa, tanto nacionales como internacionales [Joseph y Pakkeerappa, 2015]. Por lo general, el crecimiento de cualquier área costera siempre se considera desde una perspectiva comercial,mientras que el aspecto ambiental se descuida en su mayor parte. Esta estrategia conduce a un desarrollo frente a la playa poco práctico, que tiene diferentes ramificaciones negativas sobre el clima y la sociedad. Es antieconómico ya que destruye las estructuras ecológicas reales, como el paisaje de la playa, la biodiversidad y el sistema biológico en el océano y en la tierra. También el ejercicio de la industria de viajes en el territorio costero destruye la playa. Este estudio resume los impactos ambientales del turismo costero y las opciones sostenibles para hacerlo ecológico. Se sugirieron las soluciones sostenibles para una mejor conservación costera. Además, el estudio señala la futura crisis relacionada con la última Evaluación de Impacto Ambiental (EIA) 2020 del gobierno de India
Wild, Indigenous, Lame, Invalid: Anti-Ableist Epistemologies of the South
No full textThe aim of the article was to present a first approach to an epistemological proposal that reflects on and deals with the construction and legitimation of knowledge generated from abject, abnormal, or crippled corporeities geopolitically located in the South. It pays special attention to the sex-gender-ability system in the social and epistemological organization of knowledge. In this development, we identify a positionality and wasted wealth for regional social analysis and transformation as a result of a modern colonial order. Hence, this proposal is inscribed within the Latin American critical thinking to reflect on those other places of abject enunciation
Balsas de puya (Puya chilensis Molina 1782) en el litoral higromórfico de Chile entre los siglos XVI y XIX
Get PDFEn el litoral higromórfico chileno se utilizaron diversas embarcacio-nes para múltiples propósitos. Una de las menos conocidas es la balsa de troncos de puya, cuyo uso está bien documentado en la obra del historiador jesuita Die-go de Rosales (1877 [1674], 1991 [1680]). La evidencia arqueológica de su uso es indirecta (la existencia de algunas islas pobladas) y en este trabajo nos interesa evaluar la información proporcionada por Rosales, cotejándola con la entrega-da por otros europeos que observaron la balsa, antes y después de las descrip-ciones del cronista jesuita. Es importante destacar que la descripción de la bal-sa de troncos de puya se hace contra el trasfondo de la balsa andina u oceánica registrada por diversos cronistas desde el siglo XVI. A pesar de lo fragmentario de la documentación, la balsa de puya es una embarcación de gran interés para entender los diversos sistemas de navegación desarrollados en las costas del Centro Sur de Chile por los grupos que la habitaron hasta fines del siglo XIX.In the Chilean hygromorphic coast, various vessels were used for multiple purposes. One of the least known is the puya log raft, which use is well documented by the works of the Jesuit historian Diego de Rosales (1877 [1674], 1991 [1680]). The archaeological evidence of its use is indirect (the existence of some populated islands) and in this paper we intend to evaluate the informa-tion provided by Rosales, comparing it with that provided by other Europeans who observed the raft, before and after the descriptions of the Jesuit chronicler. It’s important to note that the description of the Puya log raft is made against the background of the Andean or Oceanic raft recorded by various chroniclers since the 16th century. Despite its fragmentary documentation, the puya log raft is a vessel of great importance for understanding the diverse navigation systems developed on shores of Central-South Chile by the groups that inhabi-ted it until the end of the 19th century
Validation of an instrument to evaluate the satisfaction of the professional practice in pertaining students to the program of Nutrition and Dietary
No full textIntroduction. Professional practice is a relevant process for the personal and academic development of students. It uses learning contexts located in real scenarios and enables the acquisition of knowledge, skills, and competencies necessary for professional practice.Objective. To design and validate an instrument designed to evaluate students' satisfaction with their professional practice process.Materials and methods. Mixed-method study, non-probabilistic sample by convenience of 196 participants. The sample is formed by 20Nutritionists and 176 students belonging to the Nutrition and Dietetics undergraduateprogram. The statistical software SPSS version 22 was used to analyze reliability by Cronbach'salpha and the Delphi method for content validity. An instrument with 32 items grouped in 4dimensions was elaborated and applied to 116 students to analyze reliability. The instrument was adjusted to 25 items, and content validity was analyzed by a panel of experts. The judge'sconsensus was the foundation for developing a 29-item version grouped into 4dimensions. This version was applied to 60 students to obtain Cronbach's alpha validation.Results. The instrument presents an excellent level of reliability, with a Cronbach's Alphacoefficient of 0.927.Conclusions. The instrument designed to measure satisfaction with professional practices is a reliable and valid measure, since it allows knowing the students' evaluation at the end of their professional practice proces
The Mediating Role of Cardiorespiratory Fitness in the Association between a Negative Lifestyle and Poor Mental Health in Chilean Schoolchildren
No full textBackground: A negative lifestyle has a reported relationship with psychological problems and deteriorated well-being. However, there is little information regarding the mediating role of cardiorespiratory fitness (CRF) in this relationship. Objectives: The objectives of the present study are twofold: first, to investigate the association between negative lifestyle, physical self-concept (PSC), and depression, and second, to assess the potential mediating role of CRF in this complex relationship. Methods: This cross-sectional study included 612 schoolchildren aged between 9 and 14 years from the Araucan & iacute;a region (southern Chile). CRF was measured using the Leger test, and lifestyle, depression, and PSC were measured using validated questionnaires. Results: A negative lifestyle reported an inverse association with PSC (p < 0.001) and a positive association with depression levels (p < 0.001). The mediation analysis showed that CRF was positively related to PSC (p < 0.001) and inversely related to depression (p = 0.001); besides, the indirect effect CRF acted as a partial mediator in the association between a negative lifestyle and PSC (indirect effect = -1.15; SE = 0.01; 95% CI, -1.87, -0.55) and depression levels (indirect effect = 0.22; SE = 0.08; 95% CI, 0.08, 0.38). Conclusion: In conclusion, CRF in schoolchildren played a potential mediating role in the association between a negative lifestyle and depression and PSC
Massive scalar field perturbations of black holes immersed in Chaplygin-like dark fluid
No full textWe consider massive scalar field perturbations in the background of black holes immersed in Chaplygin-like dark fluid (CDF), and we analyze the photon sphere modes, the de Sitter modes as well as the near extremal modes and discuss their dominance, by using the pseudospectral Chebyshev method and the third order Wentzel-Kramers-Brillouin approximation. We also discuss the impact of the parameter representing the intensity of the CDF on the families of quasinormal modes. Mainly, we find that the propagation of a massive scalar field is stable in this background, and it is characterized by quasinormal frequencies with a smaller oscillation frequency and a longer decay time compared to the propagation of the same massive scalar field within the Schwarzschild-de Sitter background
EXCHANGE, TERRITORIALISATION AND WOMEN IN THE CIRCULATION OF MAKUÑ IN WALLMAPU (18TH-19TH CENTURY): A CRITICAL BIBLIOGRAPHICAL REVIEW
No full textThe article analyzes the circulation and exchange of the makun/poncho textile from authors who investigate the history of Mapuche society in the eighteenth and nineteenth centuries, from the border and interethnic approach in the economic, territorial and socio-political dimensions linked to the textile garment. Differences are raised about the recognition of the role of the makun in the different dimensions presented and in the understanding of the participation of women in the processes of Mapuche economic and socio-political transformation