Mechanical analysis of Genoa 03 stirling engine

Due to the new technologies development based on renewable sources of energy, in recent years Stirling engines have become very important in the energetic sector. Many of them do not allow the use of fluid lubricants and, thus, the effect of friction losses is important. For this purpose, a mathematical model has been developed based on the force balance in the crankshaft using the pressure distribution in the cylinders. The aim of this work is to characterize the mechanical losses in a Genoa 03 Stirling engine using a numerical model and experimentally via the drag method. The results of this model have been compared with those obtained experimentally on Genoa 03 Stirling engine. In the experimental results, a proportional increase in friction torque due to the average pressure and the speed of the crankshaft is observed. The first of these is caused by an increase of dry friction forces and the second, by the viscous friction between the working fluid and the inner walls of the engine. Also in this paper, irreversible processes in a beta type Stirling engine have been investigated in order to highlight the impact of losses on mechanical power and its performance. This article develops the first study of the mechanical losses of Genoa 03 experimental Stirling engine, which has an output power of 3 kW. Although the model response follows the same trends as the experiments, those simplifications provide errors which become more significant as the engine speed increases.Ministerio de Economía y Competitividad ENE2013-43465-

A lab-scale rotary kiln for thermal treatment of particulate materials under high concentrated solar radiation: Experimental assessment and transient numerical modeling

Rotary kilns are worldwide used for industrial processes that involve thermal treatments of particulate materials. However, a great amount of fossil fuels is employed in such processes. As alternative, solar rotary kilns are considered for this application due to their versatility and potential to substitute traditional fossil-fuel driven devices. In order to boost the development of this technology, efforts have to be focused on the control of the particle temperature during the treatment. In this context, a lab-scale rotary kiln was built and tested using a 7- kWe high-flux solar simulator at University of Antofagasta. It was conceived to treat particulate materials of different nature and it is able to reach temperatures higher than 800 °C under different operation strategies. Silicon carbide was selected for initial tests because it is inert, endures high temperatures (up to 1600 °C) and it has been proposed as thermal storage vector in several researches on concentrated solar power. In a first stage, the empty kiln was preheated up to about 800 °C, reaching a steady state in less than three hours and with a power of approximately 370 W entering the kiln cavity. Afterwards, 43 g of silicon carbide were introduced in the furnace and the system was heated again up to a second steady state above 800 °C. In this stage, particles showed a fast increment of their temperature and exceeded 700 °C in less than three minutes after loading. A one-dimensional transient numerical model was also developed to perform the thermal analysis of the kiln and the estimation of both the particle temperature and the system efficiency. Numerical results showed good agreement with experimental data and thermal losses could be quantified in detail. Therefore, the model was also used to predict the thermal behavior of a solar rotary kiln working in batch mode.The authors acknowledge the financial support provided by the FONDECYT project number 3150026 of CONICYT (Chile), the Education Ministry of Chile Grant PMI ANT 1201, as well as CONICYT/ FONDAP/15110019 “Solar Energy Research Center” SERC-Chile. The authors also gratefully acknowledge the financial support received from the Sectorial Fund CONACYT-SENER-Energy Sustainability, through grant 207450, Mexican Center for Innovation in Solar Energy (CeMIE-Sol), whithin strategic project P-10 “Solar Fuels and Industrial Processes” (COSOLpi). Special thanks go to the students Lou Cardinale, Rodrigo Méndez, and Daniel Vidal who gave a precious contribution during the experimental trials at LaCoSA of University of Antofagasta

Use of rotary kilns for solar thermal applications: Review of developed studies and analysis of their potential

Rotary kilns have a long history of use in classical industries. They are able to achieve high temperatures with higher thermal efficiencies than other reactor types. Their performance has been widely studied and classified according to different parameters. Since it is a well-known technology, rotary kilns have been selected for high temperature solar processes. This article initially presents a brief review of the rotary kiln technology and it focuses on the employment of these devices for thermal and thermochemical processes conducted by concentrating solar energy. Among the solar devices, a novel rotary kiln prototype for thermochemical processes is presented and compared with a static solar reactor. Finally, some practical conclusions on the design and operation of solar rotary kilns are remarked and an analysis of their main limitations is presented.The authors acknowledge the financial support provided by the FONDECYT project number 3150026 of CONICYT (Chile), the Education Ministry of Chile Grant PMI ANT 1201, as well as CONICYT/FONDAP/ 15110019 ‘‘Solar Energy Research Center” SERC-Chile. Also, the second author wish to thank to the Plataforma Solar de Almería and the University of Almería for the collaboration and assistance devoted to the development of his Ph.D research

Estudio por elementos finitos de la biomecánica lumbar humana. Análisis de la degeneración discal

El dolor lumbar es una de las patologías crónicas más extendidas. Se dice que aproximadamente el 80% de la población va a padecer dolor lumbar o va a desarrollar una patología discal en algún momento de su vida. Algunos estudios clínicos han demostrado que el 90% de las patologías de la columna vertebral están localizadas en la columna lumbar. El uso de modelos matemáticos y simulación computacional puede servir de base para predecir la aparición y evolución de patologías lumbares. Por tanto, la metodología seguida para desarrollar este proyecto ha sido por medio de modelos computacionales de elementos finitos que pretenden simular la respuesta de los discos intervertebrales frente a distintos estados de carga y distintas patologías. Los discos intervertebrales están compuestos por tejido cartilaginoso y constan de tres regiones diferenciadas. La región interna o núcleo pulposo, una estructura altamente hidrofílica capaz de soportar el 75% de la carga, distribuyendo los esfuerzos de forma horizontal al anillo. La región externa del disco o anillo fibroso, compuesta por capas concéntricas de fibras de colágeno (cuya rigidez aumenta en las capas más exteriores) que encierran al núcleo. Y la placa terminal compuesta por una fina capa de cartílago hialino que separa el disco del cuerpo vertebral. La porosidad y permeabilidad de cada una de las partes del disco juegan un papel fundamental en su comportamiento. Debido a estas características del disco se consideran tres modelos distintos para la simulación del anillo fibroso: un primer modelo porohiperelástico fibrado en el que se incluye el caracter hidrofílico de los discos intervertebrales, un segundo modelo porohiperelástico no fibrado y un último modelo poroelástico. Se analizan cada modelo en función de los distintos discos lumbares y de la patología discal. Por otro lado, los 3 créditos ECTS correspondientes a trabajo clínico o de usuario final, han sido realizados en una empresa I+D de biotecnología (Alphasip S.L.). Estas prácticas están íntimamente relacionadas con las asignaturas de "caracterización nanométrica en biomedicina y nanosensores" y "sistemas de liberación de fármacos" impartidas en el master de Ingeniería Biomédica. El trabajo desempeñado en dicha empresa ha sido el siguiente: - Colaboración en la fabricación de biosensores de diagnóstico molecular. - Estudio del funcionamiento y correcta funcionalización de nanotubos de carbono en chips. - Control de calidad y stock de los biosensores. - Tratamiento y análisis de datos electrónicos. - Elaboración de programas informáticos para automatizar los análisis de datos. - Apoyo técnico. - Reuniones con científicos nacionales e internacionales así como con empresas privadas

Can we achieve biomimetic electrospun scaffolds with gelatin alone?

Introduction: Gelatin is a natural polymer commonly used in biomedical applications in combination with other materials due to its high biocompatibility, biodegradability, and similarity to collagen, principal protein of the extracellular matrix (ECM). The aim of this study was to evaluate the suitability of gelatin as the sole material to manufacture tissue engineering scaffolds by electrospinning.Methods: Gelatin was electrospun in nine different concentrations onto a rotating collector and the resulting scaffold’s mechanical properties, morphology and topography were assessed using mechanical testing, scanning electron microscopy and white light interferometry, respectively. After characterizing the scaffolds, the effects of the concentration of the solvents and crosslinking agent were statistically evaluated with multivariate analysis of variance and linear regressions.Results: Fiber diameter and inter-fiber separation increased significantly when the concentration of the solvents, acetic acid (HAc) and dimethyl sulfoxide (DMSO), increased. The roughness of the scaffolds decreased as the concentration of dimethyl sulfoxide increased. The mechanical properties were significantly affected by the DMSO concentration. Immersed crosslinked scaffolds did not degrade until day 28. The manufactured gelatin-based electrospun scaffolds presented comparable mechanical properties to many human tissues such as trabecular bone, gingiva, nasal periosteum, oesophagus and liver tissue.Discussion: This study revealed for the first time that biomimetic electrospun scaffolds with gelatin alone can be produced for a significant number of human tissues by appropriately setting up the levels of factors and their interactions. These findings also extend statistical relationships to a form that would be an excellent starting point for future research that could optimize factors and interactions using both traditional statistics and machine learning techniques to further develop specific human tissue

Early alterations in vascular contractility associated to changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue

Aim: To test the early effect of fructose-induced changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue (PVAT) upon vascular contractility.Methods: Adult male Wistar rats were fed a commercial diet without (CD) or with 10% fructose (FRD) in the drinking water for 3 weeks. We measured plasma metabolic parameters, lipid composition and oxidative stress markers in aortic PVAT. Vascular contractility was measured in aortic rings sequentially, stimulated with serotonin (5-HT) and high K+-induced depolarization using intact and thereafter PVAT-deprived rings.Results: Comparable body weights were recorded in both groups. FRD rats had increased plasma triglyceride and fructosamine levels. Their PVAT had an increased saturated to mono- or poly-unsaturated fatty acid ratio, a significant decrease in total superoxide dismutase and glutathione peroxidase activities and in the total content of glutathione. Conversely, lipid peroxidation (TBARS), nitric oxide content, and gluthathione reductase activity were significantly higher, indicating an increase in oxidative stress. In aortic rings, removal of PVAT increased serotonin-induced contractions, but the effect was significantly lower in rings from FRD rats. This effect was no longer observed when the two contractions were performed in PVAT-deprived rings. PVAT did not affect the contractions triggered by high K+-induced depolarization either in CD or FRD rats.Conclusions: FRD induces multiple metabolic and endocrine systemic alterations which also alter PVAT and the vascular relaxant properties of this tissue. The changes in PVAT would affect its paracrine modulation of vascular function.Facultad de Ciencias Exacta

Experimental verification of hybrid renewable systems as feasible energy sources

[EN] Renewable energies are a central element in the search for energy sustainability, so they are becoming a substantial component of the energy scenario of every country, both as systems connected to the grid or in stand-alone applications. Feasibility of these renewable energy systems could be necessary not only in their application in isolated areas, but also in systems connected to the grid, in this last case when their contribution reaches a substantial fraction of the total electricity demand. To overcome this reliability problem, hybrid renewable systems could become essential and activities to optimize their design should be addressed, both in the simulation and in the experimental areas. In this paper, a laboratory to simulate and verify the reliability of hybrid renewable systems is presented and its application to the feasibility analysis of multicomponent systems including photovoltaic panels, wind generator and biomass gasification plant, plus energy storage in a battery bank, are described.Pérez-Navarro, Á.; Alfonso-Solar, D.; Ariza-Chacón, HE.; Cárcel Carrasco, FJ.; Correcher Salvador, A.; Escrivá-Escrivá, G.; Hurtado, E.... (2016). Experimental verification of hybrid renewable systems as feasible energy sources. Renewable Energy. 86(2):384-391. doi:10.1016/j.renene.2015.08.030S38439186

Leadership, management, quality, and innovation in organ donation: 2019 Kunming recommendations for One Belt & One Road countries

The findings and recommendations of the 2019 consensus conference in organ donation, held in Kunming, China, are here reported. The main objective of the conference was to gather relevant information from experts involved in the field. The data and opinions provided allowed to propose a series of recommendations for 'One Belt & One Road Countries' on how to achieve self-sufficiency in organ donation. Leadership in organ donation should be results-oriented and goal-driven based on the principles of excellence, empowerment, and engagement, providing the means, resources, and strategies necessary to reach the goal in earnest. Management includes good governance and transparency of a national registry of patients in the waiting list, donors, transplants, transplant teams, quality, and safety programs with continuous educational training of health care professionals. Mandatory monitoring, auditing and evaluation of quality must be incorporated into donation practices as relevant points in innovation, as well as the adoption of already established and novel processes and technologies. Achievement of self-sufficiency in organ donation is a crucial step to fight against transplant tourism and to prevent organ trafficking. Based on recommendations arising from the conference, each country could review and develop individualized action plans adjusted to its own circumstances and reality

Homogeneización del proceso de tutorización del trabajo final de grado en estudiantes de Fisioterapia

La asignatura de trabajo final de grado (TFG) es una incorporación del espacio europeo con la que el alumno integra los contenidos adquiridos durante su formación. A pesar de intentar homogeneizar la formación, la inexistencia de instrucciones específicas produce diferencias en el desarrollo de los trabajos, incluso en una misma facultad debido a las diferencias metodológicas de los docentes, frustrando al alumnado. Este trabajo evaluó la influencia del uso de rúbricas y tutoriales como herramientas para homogeneizar el proceso de tutorización del TFG en el grado de satisfacción del alumnado con la asignatura. Durante dos años académicos, 9 profesores recibieron rúbricas y tutoriales para guiar la tutorización. El resto de profesores no recibieron ningún material adicional. Después de la presentación del trabajo, el alumnado contestó un cuestionario para evaluar el grado de satisfacción con el TFG. Los resultados mostraron que el uso de rúbricas no mejora la percepción de la organización de la asignatura ni del aprendizaje adquirido, así como tampoco aumenta el grado de satisfacción con el tutor y la asignatura. Sin embargo, esta metodología puede ser útil para minimizar la creencia de la exigencia de las tareas vinculadas al tutor, y con ello, la posible frustración del alumnado

Chronological and biological aging of the human left ventricular myocardium: Analysis of microRNAs contribution

Aging is the main risk factor for cardiovascular diseases. In humans, cardiac aging remains poorly characterized. Most studies are based on chronological age (CA) and disregard biological age (BA), the actual physiological age (result of the aging rate on the organ structure and function), thus yielding potentially imperfect outcomes. Deciphering the molecular basis of ventricular aging, especially by BA, could lead to major progresses in cardiac research. We aim to describe the transcriptome dynamics of the aging left ventricle (LV) in humans according to both CA and BA and characterize the contribution of microRNAs, key transcriptional regulators. BA is measured using two CA-associated transcriptional markers: CDKN2A expression, a cell senescence marker, and apparent age (AppAge), a highly complex transcriptional index. Bioinformatics analysis of 132 LV samples shows that CDKN2A expression and AppAge represent transcriptomic changes better than CA. Both BA markers are biologically validated in relation to an aging phenotype associated with heart dysfunction, the amount of cardiac fibrosis. BA-based analyses uncover depleted cardiac-specific processes, among other relevant functions, that are undetected by CA. Twenty BA-related microRNAs are identified, and two of them highly heart-enriched that are present in plasma. We describe a microRNA-gene regulatory network related to cardiac processes that are partially validated in vitro and in LV samples from living donors. We prove the higher sensitivity of BA over CA to explain transcriptomic changes in the aging myocardium and report novel molecular insights into human LV biological aging. Our results can find application in future therapeutic and biomarker research