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Para disminuir el peso de los componentes utilizados en la industria aeroespacial se han desarrollado aleaciones de aluminio de alta resistencia con litio como aleante principal. Este aleante reduce considerablemente el peso final de la aleación y mejora las propiedades mecánicas, convirtiendo a esta aleación en termotratable. Actualmente, estos materiales no se producen en el país y su importación es difícil debido a su naturaleza estratégica. Este trabajo muestra los resultados obtenidos del estudio de los efectos del control de la velocidad de enfriamiento de la aleación AA2195. El análisis se realizó mediante micrografías y ensayos de dureza. Se observa la formación de estructuras de Widmanstätten con enfriamiento lento tras el recocido, lo que impide el conformado plástico. Con el uso de temple tras el recocido, se inhibe la formación de estas estructuras, mejorando notablemente la trabajabilidad de la aleación.  

El presente trabajo muestra una comparativa de estudios realizados a torres de enfriamiento húmedas a contraflujo para sintetizar aportes, estudios y metodologías que permitan dar un contexto reciente al estado actual de la investigación en este campo. Este trabajo parte desde los fundamentos básicos en torres de enfriamiento, sus secciones de estudio y problemáticas a resolver, con un enfoque hacia el consumo de agua en los procesos evaporativos por transferencia de calor en gotas de agua para calcular las pérdidas de agua por evaporación y arrastre. Se revisan y discuten los fundamentos de torres de enfriamiento y aplicaciones generales, los métodos comunes de investigación en torres de enfriamiento utilizados, con énfasis en las características particulares según el tipo de estudio, ya sea desde el punto de vista de diseño de la torre de enfriamiento, las características que afectan su funcionamiento o desempeño, los fundamentos de análisis energético, las sugerencias en la realización de estudios numéricos y simulaciones por CFD, además de su validación correspondiente mediante estudios experimentales. La información recopilada en este trabajo proporciona una visión general y simplifica los avances esenciales en la reducción de las pérdidas por evaporación y arrastre en torres de enfriamiento a contraflujo, las características y tendencias en el desarrollo de modelos matemáticos computacionales y recomendaciones para llevar a cabo estudios teóricos y experimentales para comprender más ampliamente los mecanismos de transferencia de calor y masa.

A study of an alternative ejector cooling system is proposed in this paper. A mathematical model without irreversibility is developed and simulated. The numerical results are validated with literature data for two working fluids (R134a and R152a). The performance and behavior of the system using conventional refrigerants (HFC's, HC's) and unconventional (R717, R718) is obtained; the process uses 100 kW of heat available in a waste stream. Finally, the paper explores the reduction of problems associated with the use of conventional refrigerants by introducing the use of R718 (water) as the working fluid of the proposed system.

Introduction: Laser treatment of biological tissue generates significant heat, which can lead to thermal damage if not properly controlled. Cooling systems play a critical role in minimizing this risk. Objective: The objective of this study was to evaluate the temperature distribution in biological tissue during laser treatment and to analyze the effectiveness of an air-cooled heat exchanger in controlling excessive heating. Methodology: A transient thermal analysis was carried out to simulate the combined process of laser irradiation and air-cooling. In parallel, experimental tests were conducted to validate the numerical predictions. Results: The findings indicated that, in the absence of cooling, the tissue surface temperature exceeded 85 °C, creating a risk of thermal injury. With the integration of the air-cooled heat exchanger, the maximum surface temperature was reduced to 72.4 °C, while the temperature at a 2 mm depth was maintained at 58.2 °C. The cooling system promoted a rapid post-exposure temperature drop and limited the temperature gradient between surface and deeper layers to 8–12 °C. Discussion: The results demonstrated consistency with existing literature on the importance of cooling techniques in medical laser applications. The cooling mechanism not only improved heat dissipation but also reduced the risk of overheating compared with previously reported systems. Conclusions: This study confirmed that precise thermal management is essential for safe and efficient laser treatment. The integration of an air-cooled heat exchanger enhances treatment efficiency and minimizes tissue damage. Introducción: El tratamiento con láser de tejidos biológicos genera un calor considerable, lo que puede provocar daños térmicos si no se controla adecuadamente. Los sistemas de refrigeración desempeñan un papel fundamental para minimizar este riesgo. Objetivo: El objetivo de este estudio fue evaluar la distribución de temperatura en el tejido biológico durante un tratamiento con láser y analizar la eficacia de un intercambiador de calor refrigerado por aire en el control del sobrecalentamiento. Metodología: Se realizó un análisis térmico transitorio para simular el proceso combinado de irradiación láser y enfriamiento por aire. Paralelamente, se llevaron a cabo pruebas experimentales para validar las predicciones numéricas. Resultados: Los hallazgos indicaron que, en ausencia de refrigeración, la temperatura superficial del tejido superaba los 85 °C, lo que generaba un riesgo de lesión térmica. Con la incorporación del intercambiador de calor refrigerado por aire, la temperatura máxima en la superficie se redujo a 72,4 °C, mientras que a 2 mm de profundidad se mantuvo en 58,2 °C. El sistema de refrigeración favoreció una rápida disminución de la temperatura tras la exposición y limitó el gradiente térmico entre la superficie y las capas más profundas a 8–12 °C. Discusión: Los resultados mostraron coherencia con la literatura existente sobre la importancia de las técnicas de refrigeración en aplicaciones médicas con láser. El mecanismo de enfriamiento no solo mejoró la disipación del calor, sino que también redujo el riesgo de sobrecalentamiento en comparación con sistemas reportados previamente. Conclusiones: Este estudio confirmó que una gestión térmica precisa es esencial para un tratamiento con láser seguro y eficaz. La integración de un intercambiador de calor refrigerado por aire mejora la eficiencia del tratamiento y minimiza el daño tisular. Introdução: O tratamento com laser de tecidos biológicos gera um calor considerável, que pode provocar danos térmicos se não for controlado adequadamente. Os sistemas de refrigeração desempenham um papel fundamental para minimizar este risco. Objectivo: O objectivo deste estúdio foi avaliar a distribuição da temperatura no tecido biológico durante um tratamento com laser e analisar a eficácia de um permutador de calor arrefecido a ar no controlo do sobreaquecimento. Metodologia: Foi realizada uma análise térmica transitória para simular o processo combinado de irradiação laser e arrefecimento por ar. Paralelamente, foram levados ao cabo testes experimentais para validar as previsões numéricas. Resultados: Os hallazgos indicam que, em ausência de refrigeração, a temperatura superficial do tecido ultrapassa os 85 °C, o que gera um risco de lesão térmica. Com a incorporação do permutador de calor arrefecido a ar, a temperatura máxima à superfície é reduzida para 72,4 °C, enquanto 2 mm de profundidade é mantida a 58,2 °C. O sistema de refrigeração favoreceu uma rápida diminuição da temperatura para além da exposição e limitou o gradiente térmico entre a superfície e as capas mais profundas a 8–12 °C. Discussão: Os resultados mostram coerência com a literatura existente sobre a importância das técnicas de refrigeração em aplicações médicas com laser. O mecanismo de arrefecimento não só melhorou a dissipação de calor, como também reduziu o risco de sobreaquecimento em comparação com os sistemas anteriormente reportados. Conclusões: Este estudo confirmou que uma gestão térmica precisa é essencial para um tratamento com laser seguro e eficaz. A integração de um permutador de calor arrefecido a ar melhora a eficiência do tratamento e minimiza os danos nos tecidos.

Job's tears is an essential cereal with rich nutrients and functional chemical compositions. However, systematic knowledge of its starch content is still lacking. This study sought to investigate the resistant starch (RS) properties prepared from Job's tears starch by autoclaving-cooling treatment. RS contents for native and autoclave-cooled Job's tears starches were measured as 8.35%-10.53% and 26.57%-31.65%, respectively. The \"Maltese crosses\" of RS disappeared, and its morphology exhibited irregular sheet structure with layered strips and gully shapes on the surface. Additionally, the XRD pattern of RS presented a combination of B and V types, and disrupted short-range ordered structure. Compared with native starch, the water solubility, swelling power, light transmittance, and water- holding capacity of RS were higher, whereas its hardness, chewiness, resilience, and gumminess were significantly lower. These results will provide insights into the future study of starch in Job's tears and application of RS in the food industry.

Background: The production of biofuels has caused an increase in the prices of agricultural commodities. Thus, the ecological footprint, social inclusion and profitability of production systems have encouraged the use of agroindustrial products as an alternative in ruminant feeds. Objective: To evaluate carcass yields, noncarcass components, and the economic viability of including licuri oil in diet of Santa Ines ewes. Methods: A total of 32 Santa Ines ewes (multiparous, nonlactating, 2–4 years old, and 36.7±0.87 kg of body weight—BW) were allotted to a randomized block design with four treatments (diets containing 0, 2, 4 or 5% licuri oil) with eight replicates per treatment, and confined for 77 days. Results: The incremental inclusion of licuri oil promoted a quadratic response on slaughter BW, carcass and true yields, chest widths, heart fat, pancreas, omental fat, and ribeye area (p<0.05). Carcass, heart and loin weight, shank yield, fat thickness and loin fat were reduced (p<0.05); while cooling losses, left halfcarcass weight, saw blade yield, and proportion of meat in the loin increased (p<0.05) with increasing dietary levels of licuri oil. The control diet resulted in the best gross revenue (USD $609.39); however, there was a loss (USD$ 50.96) regarding economic performance indicators. Conclusion: The use of up to 2% licuri oil in the diet increased carcass yield of discard ewes.

Las casas-patio tradicionales de la ciudad de Lima fueron edificadas bajo una evidente influencia árabe, en lo constructivo, formal y estilístico. La similitud en el clima desértico litoral permitió la transferencia de algunas estrategias bioclimáticas, entre ellas una disposición particular con dos patios. La ubicación relativa, escala y acabados de dichos patios sugieren la intención de calentar el primero y más amplio, procurando mantener más fresco y húmedo el segundo, y con ello inducir la ventilación por convección de modo que el aire atraviese los ambientes principales. El estudio pretende identificar la presencia de dicha estrategia, para lo cual se realizó un monitoreo energético de la Casa Riva-Agüero en un día cálido y soleado de verano. Los resultados permitieron demostrar que sí se logra activar una ventilación por convección entre los patios, ayudando a mantener los niveles de temperatura al interior de los espacios principales dentro de rangos confortables.

The mechanisms imposing a gibberellin (GA) requirement to promote the germination of dormant and non-dormant Arabidopsis seeds were analyzed using the GA-deficient mutant ga1, several seed coat pigmentation and structure mutants, and the abscisic acid (ABA)-deficient mutant aba1. Testa mutants, which exhibit reduced seed dormancy, were not resistant to GA biosynthesis inhibitors such as tetcyclacis and paclobutrazol, contrarily to what was found before for other non-dormant mutants in Arabidopsis. However, testa mutants were more sensitive to exogenous GAs than the wild-types in the presence of the inhibitors or when transferred to a GA-deficient background. The germination capacity of the ga1-1 mutant could be integrally restored, without the help of exogenous GAs, by removing the envelopes or by transferring the mutation to a tt background (tt4 and ttg1). The double mutants still required light and chilling for dormancy breaking, which may indicate that both agents can have an effect independently of GA biosynthesis. The ABA biosynthesis inhibitor norflurazon was partially efficient in releasing the dormancy of wild-type and mutant seeds. These results suggest that GAs are required to overcome the germination constraints imposed both by the seed coat and ABA-related embryo dormancy.

The sterile insect technique (SIT) is as an important component to the area-wide integrated management of the false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), which was successfully implemented in the Western Cape region of South Africa and subsequently expanded to citrus areas in the Eastern Cape region of South Africa. This integrated control program, which transports sterile moths from a rearing facility in Citrusdal, South Africa to orchards in both the Western and Eastern Cape, must continuously examine production, handling, processing, transport, and release protocols to ensure the delivery of high-quality sterile moths. While the use of cold temperature to immobilize moths is standard protocol for SIT programs to increase the density of moths for purposes of collecting, handling, irradiation, transport and release, some concern has been raised that rapid chilling and long cold temperature storage of moths may negatively impact field performance of some insectary-reared insects. We conducted trials to examine the effect of irradiation with 150 Gy of gamma rays and cold temperature storage on the performance of T. leucotreta moths released in citrus orchards. The radiation treatment did not significantly affect the performance of T. leucotreta moths released in citrus orchards. However, compared with moths held at room temperature, moths that were rapidly chilled were less likely to be captured in pheromone traps and less likely to disperse as great distances following release in citrus orchards. Additional research is needed to identify an alternative to rapid chilling and cold temperature storage that does not impair mating competitiveness and dispersal of irradiated T. Leucotreta adults. Procedural changes that will maintain or enhance sterile T. leucotreta moth quality and performance in the field, while allowing for the cost-effective handling and processing of the sterile moths, need to be considered.

Transgenic tobacco seedlings that overexpress a cDNA encoding an enzyme with both glutathione S-transferase (GST) and glutathione peroxidase (GPX) activity had GST- and GPX-specific activities approximately twofold higher than wild-type seedlings. These GST/GPX overexpressing seedlings grew significantly faster than control seedlings when exposed to chilling or salt stress. During chilling stress, levels of oxidized glutathione (GSSG) were significantly higher in transgenic seedlings than in wild-types. Growth of wild-type seedlings was accelerated by treatment with GSSG, while treatment with reduced glutathione or other sulfhydryl-reducing agents inhibited growth. Therefore, overexpression of GST/GPX can stimulate seedling growth under chilling and salt stress, and this effect could be caused by oxidation of the glutathione pool.