Search

The urgent climate situation resulting from the indiscriminate consumption of fossil fuels together with the current geopolitical instability has prompted a series of policies in Europe to boost the energy transition through the large-scale installation of renewable energy sources (RES). To combat the intermittency and fluctuations associated with their operation, renewable hydrogen is presented as a versatile solution to decarbonize different economic sectors. Hence, the design and implementation of a hybrid renewable-hydrogen power system has turn out in the first electrically self-sufficient social housing of Spain installed in the town of Novales (Cantabria, Spain). The entire process is automated and controlled by a programmable logic controller (PLC) and monitored by a SCADA system. Under this framework, the HY2RES project proposes a digital twin (DT) modeling of the pilot plant to optimize the control system and the operating parameters thanks to the application of machine learning (ML) and artificial intelligence (AI) techniques to the data collected. The paper shows some initial results of the proposed DT, which features the electrical components of the physical system. The obtained results both validate the proposed methodology and evince the possibilities brought by it.

Mineral oil has traditionally been used as a cooling fluid in power transformers, but its low biodegradability and low fire point have motivated the search of alternatives. In this work, six different dielectric fluids have been studied, including four vegetable liquids, from sunflower, rapeseed, soybean, and palm, one synthetic ester and a mineral oil used for comparison. These oils were subjected to an accelerated thermal ageing in glass vessels at 150°C for four weeks (672 hours) in presence of Kraft insulating paper. Different oils parameters were measured during the ageing, i.e. breakdown voltage, dielectric dissipation factor, permittivity, DC resistivity, density, kinematic viscosity, flash and fire points, interfacial tension, acidity, and dissolved gases; additionally, the degree of polymerisation (DP) of the paper was measured. Results showed that the changes of the natural esters properties, except for the palm oil, were similar along the ageing time. Palm oil results were similar to those of the mineral oil, whereas synthetic ester showed a behaviour similar to natural esters. The kraft paper degradation was higher in the mineral oil, followed by the synthetic ester and the palm oil. No significant differences were found in the ageing with the natural esters.

The structural elements within power transformers are commonly constructed from high-density pressboard, chosen for its favourable mechanical and dielectric properties. Among these elements are the spacers employed in the windings of transformers, which endure compressive loading during operation. The spacers are immersed in dielectric fluid and exposed to high temperatures and chemical reactions over the transformer's lifespan, resulting in the degradation of their dielectric and mechanical properties. The mechanical integrity of the power transformer significantly relies on these factors; hence, it is imperative to comprehend how ageing deteriorates the mechanical response of the high-density pressboard.The present article presents experimental data on the compressive mechanical properties of a commercially available high-density pressboard, commonly employed in power transformer spacers, under various ageing conditions (induced through accelerated thermal ageing and assessed by the degree of polymerisation). These data hold potential for diverse applications. They can enhance the existing comprehension of the mechanical behaviour and degradation mechanisms of cellulosic insulation in power transformers and provide reference benchmarks for comparison with factory-obtained values by manufacturers. In the realm of engineering failure analysis, these values can be utilised to evaluate the mechanical failures of paper-based materials utilised as structural components in power transformers.

RESUMEN Introducción. El compromiso tumoral metastásico del melanoma al tracto genitourinario es frecuente, pero, la metástasis a vejiga es rara, constituye menos del 2% de los casos. Sin embargo, en autopsias realizadas a pacientes con melanoma se ha encontrado metástasis en la vejiga en entre un 18% y un 37% de los casos, lo que la convierte en la segunda en incidencia posterior al adenocarcinoma gástrico. La media de supervivencia suele ser entre 6 - 7.5 meses. El objetivo de este trabajo es presentar el caso de un melanoma metastásico a vejiga, entidad poco frecuente y poco diagnosticada por ser la mayoría de las veces asintomática. Presentación del caso. Paciente femenina de 62 años, con antecedente de melanoma al nivel del primer artejo del pie, con manejo quirúrgico y farmacológico. Consultó por hematuria. La cistoscopia evidenció una lesión única sólida, eritematosa, con necrosis y fácil sangrado y se indicó realizar resección transuretral (RTU). La patología demostró compromiso por melanoma ulcerado metastásico. Se inició manejo de segunda línea (Pembrolizumab) y presentó progresión a miembros superiores y recaída a nivel vesical. La paciente falleció un año después. Discusión. Las metástasis de melanoma al tracto genitourinario son frecuentes, pero las metástasis vesicales aisladas son raras. El tratamiento suele ser RTU de la lesión, cistectomía, quimioterapia y radioterapia. La RTU es curativa para las lesiones restringidas al epitelio, aunque la cistectomía radical suele ser la terapia de elección ante un paciente con un tumor localizado. El Pembrolizumab ha demostrado aumentar la supervivencia. El pronóstico depende del tamaño y profundidad de la invasión. Conclusiones. El compromiso vesical metastásico es poco frecuente y diagnosticado, puede estar presente en pacientes con melanoma, síntomas irritativos urinarios no específicos y hematuria. Suele ser de mal pronóstico, y requiere de manejo quirúrgico asociado a manejo sistémico. ABSTRACT Introduction. Metastatic tumor compromise of melanoma to the genitourinary tract is frequent, but metastasis to the bladder is rare, representing less than 2% of cases. However, autopsies performed on patients with melanoma have found metastases in the bladder in 18-37% of cases, making it the second incidence after gastric adenocarcinoma. The median survival is usually 6 to 7.5 months. The objective of this work is to present the case of a metastatic melanoma to the bladder, a rare and underdiagnosed condition because most of the time it is asymptomatic. Case Presentation. 62-year-old female patient, with a history of melanoma at the level of the first toe, with surgical and pharmacological management. The reason for consultation was hematuria. Cystoscopy revealed a single solid, erythematous lesion with necrosis and easy bleeding, and a transurethral resection (TUR) was indicated. The pathology found compromise for metastatic ulcerated melanoma. Second-line treatment (Pembrolizumab) was started and presented progression to the upper limbs and relapse at the bladder level. The patient died a year later. Discussion. Melanoma metastases to the genitourinary tract are common, but isolated bladder metastases are rare. Treatment is usually TUR of the lesion, cystectomy, chemotherapy, and radiation therapy. TUR is curative for lesions restricted to the epithelium, although radical cystectomy is usually the therapy of choice in patients with a localized tumor. Pembrolizumab has been shown to increase survival. The prognosis depends on the size and depth of the invasion. Conclusions. Metastatic bladder compromise is rare and underdiagnosed, it may be present in patients with melanoma, non-specific urinary irritative symptoms, and hematuria. It tends to have a poor prognosis, and requires surgical management associated with systemic management. RESUMO Introdução. O comprometimento do tumor metastático do melanoma no trato geniturinário é comum, mas a metástase na bexiga é rara, constituindo menos de 2% dos casos. Entretanto, em autópsias realizadas em pacientes com melanoma, foi encontrada metástase na bexiga entre 18% e 37% dos casos, o que a torna a segunda em incidência após o adenocarcinoma gástrico. A média de sobrevivência é geralmente entre 6 - 7,5 meses. O objetivo deste trabalho é apresentar o caso de um melanoma metastático na bexiga, uma entidade pouco frequente e subdiagnosticada, pois na maioria das vezes é assintomática. Apresentação do caso. Paciente do sexo feminino, 62 anos, com antecedentes de melanoma no nível do hálux, com manejo cirúrgico e farmacológico. Ela consultou por hematúria. A cistoscopia revelou uma única lesão sólida, eritematosa com necrose e sangramento fácil, e foi indicada uma ressecção transuretral (RTU). A patologia mostrou comprometimento de melanoma ulceroso metastático. O tratamento de segunda linha (Pembrolizumab) foi iniciado e a patologia avançou para os membros superiores e uma recaída no nível da bexiga. A paciente morreu um ano depois. Discussão. As metástases de melanoma para o trato geniturinário são frequentes, mas as metástases vesicais isoladas são raras. O tratamento é geralmente RTU da lesão, cistectomia, quimioterapia e radioterapia. A RTU é curativa para lesões restritas ao epitélio, embora a cistectomia radical seja geralmente a terapia de escolha para um paciente com um tumor localizado. O Pembrolizumab demonstrou aumentar a sobrevivência. O prognóstico depende do tamanho e da profundidade da invasão. Conclusões. O comprometimento vesical metastático é raro e subdiagnosticado, pode estar presente em pacientes com melanoma, sintomas irritantes urinários não específicos e hematúria. Geralmente tem um prognóstico negativo e requer manejo cirúrgico em associação com manejo sistêmico.

The mitigation of greenhouse gases (GHG) triggered by the broad employment of fossil fuels requires a complete energy transition towards the utilization of renewable energy sources (RES), the increase in the efficiency of the systems, implementation of carbon, capture, storage, and utilization (CCSU) technologies to decarbonize the use of fossil fuels and switch to zero-emissions energy carriers. Thus, hydrogen has emerged as a clean and versatile energy carrier that ensures a higher RES penetration that is fundamental to achieving the required energy transition. In this context, the SUDOE ENERGY PUSH project combines RES, novel hydrogen technologies, building information modelling (BIM) methodology, and passive renovation to improve the energy efficiency of social housing in the regions of south-western Europe. In this context, the techno-economic feasibility of a combined renewable hydrogen-based system (RHS) to supply electricity to a residential building has been analyzed in three different locations across the SUDOE region (Spain, France and Portugal) where a pilot plant will be deployed. The evaluation has been carried out by means of HOMER Pro software, studying every configuration in terms of dimensions, energy mix, levelised cost of energy (LCOE), net present cost (NPC) and pollutant emissions. The work reflects a greater potential and competitiveness of an RHS located in Portugal as it is the location with the greatest RES potential and the highest electricity price.

Reverse electrodialysis (RED), an emerging membrane-based technology, harnesses salinity gradient energy for sustainable power generation. Accurate characterization of electrical parameters in RED stacks is crucial to monitoring its performance and exploring possible applications. In this study, a DC electronic load module (DCELM) is implemented in a constant current condition (CC mode) for characterization of lab scale RED process, using a RED prototype in-house designed and manufactured (RU1), at different data capture setups (DCS), on which the total number of steps for data capture (NS) and the number of measurements per step (ρ) are the parameters that were modified to study their effect on obtained electrical parameters in RED. NS of 10, 50, and 100 and ρ of 10 and 20 were used with this purpose. The accuracy of resulting current and voltage steps can be enhanced by increasing NS and ρ values, and according to obtained results, the higher accuracy of resulting output current and voltage steps, with low uncertainty of the average output steps (AOS) inside the operational region of power curve, was obtained using a DCS of NS = 100 and ρ = 20. The developed DCELM is a low-cost alternative to commercial electronic load devices, and the proposed methodology in this study represents an adaptative and optimizable CC mode characterization of RED process. The results obtained in this study suggest that data capture conditions have a direct influence of RED performance, and the accuracy of electrical parameters can be improved by optimizing the DCS parameters, according to the required specifications and the scale of RED prototypes.

Finding stable solutions for hydrogen storage is one of the main challenges to boosting its deployment as an energy vector and contributing to the decarbonization of the energy sector. In this context, sodium borohydride (NaBH4) has been largely studied as a hydrogen storage material due to its significant advantages, such as low pressure, stability, and high hydrogen storage density. The development of catalysts and additive materials for the on-demand hydrolysis of NaBH4 for hydrogen release is a key research area. This work studies the effects of non-toxic and environmentally friendly additives for the hydrolysis process in terms of yield, lag time, hydrogen generation rate, and gravimetric density. Specifically, four additives, including sodium carboxymethylcellulose (CMC), polyacrylamide (PAM), sodium dodecyl sulfate (SDS), and β-cyclodextrin (BCD), were studied for their application in the storage and release of hydrogen. The best results were provided by the use of sodium carboxymethyl cellulose and polyacrylamide. In the first case, a hydrolysis yield of 85%, a lag time of 70 s, a hydrogen production rate of 1374 mL·min−1·gcat−1, and a storage capacity of 1.8 wt% were obtained. Using polyacrylamide as additive, a hydrolysis yield of almost 100% was achieved, although it required a significantly higher time period for complete conversion.

The application of alternative dielectric oils as esters in power transformers is hindered by the lack of knowledge regarding their properties and respecting which are the best techniques to ensure their proper performance. In this sense one of the fields needing an impulse is the impregnation processes of transformers cellulosic materials with these alternative oils, currently impregnated in most of the cases with mineral oils. This paper studies the impregnation behavior of eight usual dielectric solids, with two esters and a traditional mineral oil. Empirical equations of the impregnation evolution with time have been obtained, from these the rigid cellulosic materials present in the transformers and the viscosity of the dielectric oils have been identified as the key materials and properties to consider during impregnation. An adaptation of the current impregnation processes to the alternative oils have been proposed by increasing their temperature from ambient temperature up to 61-74°C, depending on the viscosity of the oil used.

Salinity gradient energy has gained attention in recent years as a renewable energy source, especially employing reverse electrodialysis technology (RED), which is based on the role of ion exchange membranes. In this context, many efforts have been developed by researchers from all over the world to advance the knowledge of this green source of energy. However, the influence of divalent ions on the performance of the technology has not been deeply studied. Basically, divalent ions are responsible for an increased membrane resistance and, therefore, for a decrease in voltage. This work focuses on the estimation of the resistance of the RED membrane working with water flows containing divalent ions, both theoretically by combining the one-thread model with the Donnan exclusion theory for the gel phase, as well as the experimental evaluation with Fumatech membranes FAS-50, FKS-50, FAS-PET-75, and FKS-PET-75. Furthermore, simulated results have been compared to data recently reported with different membranes. Besides, the influence of membrane resistance on the overall performance of reverse electrodialysis technology is evaluated to understand the impact of divalent ions in energy generation. Results reflect a minor effect of sulfate on the gross power in comparison to the effect of calcium and magnesium ions. Thus, this work takes a step forward in the knowledge of reverse electrodialysis technology and the extraction of salinity gradient energy by advancing the influence of divalent ions on energy recovery.

In recent years, the need to reduce energy consumption worldwide to move towards sustainable development has led many of the conventional technologies used in the industry to evolve or to be replaced by new alternatives. Oxygen is a compound with diverse industrial and medical applications. For this reason, obtaining it from air is one of the most interesting separations, traditionally performed by cryogenic distillation and pressure swing adsorption, two techniques which are very energetically expensive. In this sense, the implementation of membranes in a hollow fiber configuration is presented as a much more efficient alternative to carry out this separation. The aim of this work is to develop cost-effective multilayer hollow fiber composite membranes made of Matrimid and polydimethylsiloxane (PDMS) for the separation of oxygen and nitrogen from air. PDMS is used as a cover layer but can also enhance the performance of the membrane. In order to compare these two materials, three different configurations are studied. First, integral asymmetric Matrimid hollow fiber membranes were produced using the spinning method. Secondly, by using dip-coating method, a PDMS dense selective layer was deposited on a self-made polyvinylidene fluoride (PVDF) hollow fiber support. Finally, the performance of a dual-layer hollow fiber membrane of Matrimid and PDMS was studied. Membrane morphology was characterized by SEM and separation performance of the membranes was evaluated by mixed-gas permeation experiments. The novelty presented in this work is the manufacture of hollow fiber membranes and the way Matrimid is treated. This makes it possible to develop much thinner dense layers than in the case of flat-sheet membranes, which leads to higher permeance values. This is a key factor when implementing this technology on an industrial scale. Membranes prepared in this work were compared to the current state of the art, reporting quite good performance for the dual-layer membrane, reaching O2 permeance of 30.8 GPU and O2/N2 selectivity of 4.7, with a thickness of about 5–10 μm (counting both selective layers). In addition, the effect of operating temperature on the membrane permeances has been studied experimentally; we analyze its influence on the selectivity of the separation process.

The very high-power transformer lifespan depends mainly on the temperature that cellulose insulation reaches during its operation. Traditionally, its cooling has been carried out using mineral oil as coolant. Nowadays, alternative ester-based liquids are under study as substitutes due to their better environmental and fire-safety properties. This paper compares the cooling capacity of two ester-based fluids with that of a mineral oil using a 3D numerical model of a 100 MVA low voltage winding of a power transformer with axial cooling system and ONAN cooling mode. Heat-run test results with mineral oil have been used to validate this model. As a first approximation, according to the comparison developed, ester-based fluids could replace mineral oils in this type of transformers when they are going to work in a range of powers close to the rated one.

The growing interest in the production of biofuels has motivated numerous studies on separation techniques that allow the separation/concentration of organics produced by fermentation, improving productivity and performance. In this work, the preparation and characterization of new butanol-selective membranes was reported. The prepared membranes had a hollow fiber configuration and consisted of two dense selective layers: a first layer of PEBA and a second (outer) layer of PDMS. The membranes were tested to evaluate their separation performance in the selective removal of organics from a synthetic ABE solution. Membranes with various thicknesses were prepared in order to evaluate the effect of the PDMS protective layer on permeant fluxes and membrane selectivity. The mass transport phenomena in the pervaporation process were characterized using a resistances-in-series model. The experimental results showed that PEBA as the material of the dense separating layer is the most favorable in terms of selectivity towards butanol with respect to the other components of the feed stream. The addition of a protective layer of PDMS allows the sealing of possible pinholes; however, its thickness should be kept as small as possible since permeation fluxes decrease with increasing thickness of PDMS and this material also has greater selectivity towards acetone compared to other feed components.

Amidst the new techniques facing the improvement of cooling and insulating efficiency and the design of electric transformers, constrained by the current technologies, one of the more promising is the substitution of traditional dielectric oils for nanofluids. Research on nanofluids for their application in transformers as a coolant and dielectric medium have been performed during the last two decades and continue today. This review tries to collect and analyze the available information in this field and to offer it already dissected to researchers, focusing on the preparation methods and how nanoparticles affect the main properties of the base fluids. Here we also addressed the influence of different parameters as particle characteristics or environmental conditions in nanofluids performance, the evolution with time of the measured properties, or the neighboring relationship of nanofluids with other transformer components. In this sense, the most reviewed articles reflect enhancements of thermal conductivity or dielectric strength, as well as an improvement of time evolution of these properties, with respect to those that are found in base fluids, and, also, a better interaction between these nanofluids and dielectric cellulosics. Thus, the use of dielectric nanofluids in transformers may allow these machines to work safer or over their design parameters, reducing the risk of failure of the electrical networks and enhancing their life expectancy. Nevertheless, these advantages will not be useful unless a proper stability of nanofluids is ensured, which is achieved in a small part of revised articles. A compendium of the preparation methodology with this aim is proposed, to be checked in future works.

The solid insulation in the windings of power transformers, which generally consists of oil-impregnated thin paper, is one of the key elements for the performance and durability of these electrical machines. Insulation paper is subjected to static and dynamic forces of electromagnetic origin, in combination with high temperatures and chemical reactions, during the operating life of a power transformer. The mechanical properties of the cellulosic insulation are relevant parameters because its breakage could result in the electric failure of the transformer. Indeed, paper manufacturers usually provide values of the tensile strength and elongation at breakage of the insulating paper in its two principal material directions, the MD (machine direction) and CD (cross-direction). However, paper is a highly anisotropic material and its material properties evolve as the paper insulation ages. The paper insulation in an operating transformer is subjected to a multiaxial stress state field including compressive and shear stresses. This article reports experimental data on the tensile and compressive mechanical properties of two types of paper, plain Kraft and crepe paper, typically used as insulation in power transformers, under different ageing states (which were induced through accelerated thermal ageing and quantified by means of the degree of polymerisation). These data could be reused for several purposes. They can improve the current understanding of the mechanical response and degradation processes of the cellulosic insulation in power transformers, and give some reference values that can be compared with others obtained in the factory by manufacturers. In the field of engineering failure analysis, those values could be reused for the assessment of mechanical failure of paper materials used in power transformers, see [1].

El fenómeno del cierre urbano constituye una faceta del desarrollo habitacional de afianzada popularidad en Latinoamérica, en México la crisis securitaria actual incide en la percepción de vulnerabilidad, lo que ha favorecido su implementación masiva. La relación entre el miedo y el encierro se analiza desde el concepto de agorafobia urbana, categoría analítica que incorpora cuatro aspectos fundamentales: global, de Estado, social e individual. Partiendo del concepto de seguridad como bien colectivo y commodity —entendido como bien asequible—, y mediante el uso de técnicas etnográficas urbanas (entrevistas, narrativa, mapas cognitivos) se busca comprobar la premisa de que el residente, al adquirir una vivienda en estos desarrollos cerrados, apuesta por la obtención de un blindaje imaginario al entorno inseguro de la ciudad abierta mediante su participación en un sentido de membresía y comunitario hipotéticamente más estrecho y participativo, donde la convivencia entre iguales y el control le brindan seguridad. El objetivo del artículo es develar y entender los miedos, expectativas, experiencia y elecciones residenciales desde la narrativa de los habitantes del caso de estudio; la trama de relación intracomunitaria es un instrumento defensivo emergente frente a entornos considerados adversos. Como resultado de esta investigación, se identificaron conflictos por la limitada capacidad en la toma de decisiones y por la administración condominal, lo que debilita el sentido de pertenencia, la identificación intravecinal y, además, se generan procesos de retribalización y blindaje frente a la desconfianza y el conflicto, lo que se aleja de la utopía armónica y segura del mundo intramuros.

This contribution presents the early results of a R&D collaboration established between the University of Cantabria and the Power Transformer Manufacturer EFACEC. This paper tests two different techniques of steady state thermal modelling applied to power transformer windings, Computational Fluid Dynamics (CFD) and Thermal-Hydraulic Network Modelling (THNM). The state of the art of thermal modelling demonstrates that these techniques have been used to calculate both average and hotspot winding temperatures by solving the winding temperature and flows profiles within the winding. THNM models have worse accuracy than CFD in the predicted results. The improvement of these THNM models is a topic of study in transformer thermal modelling. The first goal of this paper is to test the accuracy of a new calibrated THNM model of a disc-type winding immersed in mineral oil. Then, this THNM model is tested with ester-based liquids, such as a natural ester and a synthetic ester, to determine if it can be applied to these liquids without further calibrations. Finally, the cooling performance of both type of liquids is compared using only the THNM model results. The results of this work show that the THNM model developed herein gives good estimations of temperatures compared to those obtained with CFD for both types of liquids. Also, the use of alternative fluids leads to lower temperatures when considering the same oil flow rate and temperature as inlet boundary condition.

In recent years, the use of biodegradable fluids as liquid insulation for distribution and power transformers is spreading. The main biodegradable fluids used are natural and synthetic esters, although biodegradable hydrocarbons have been recently proposed. Biodegradable fluids have a much lower environmental impact than mineral oil, limiting the risk of soil contamination in leaks, which makes them a suitable solution for applications such as offshore transformers or railway transformers. Additionally, these fluids have a higher flash point than conventional mineral oils, which dramatically reduces the risk of fire and collateral damage derived from explosion and fire. Despite these advantageous factors, there are still some aspects that hinder the broadening of their use, such as the difference in thermal properties or the lack of accepted maintenance procedures for transformers that use them as liquid insulation. This paper presents the current status of biodegradable insulating fluids, analyzing some of their properties and discussing the aspects that are still to be investigated in order to make them a real alternative to petroleum-based fluids.

Over the last few decades the insulating performance of transformer oils has been broadly studied under the point of view of nanotechnology, which tries to improve the insulating and heat dissipation performance of transformer oils by suspending nanoparticles. Many authors have analyzed the thermal and dielectric behavior of vegetable oil based-nanofluids, however, very few works have studied the evolution of these liquids during thermal aging and their stability. In this paper has been evaluated the performance of aged vegetable oil based-nanofluids, which have been subjected to accelerated thermal aging at 150 °C. Nanoparticles of TiO2 and ZnO have been dispersed in a commercial natural ester. Breakdown voltage, resistivity, dissipation factor and acidity of nanofluid samples have been measured according to standard methods, as well as stability. Moreover, it has been analyzed the degradation of Kraft paper through the degree of polymerization (DP). The results have showed that although nanoparticles improve breakdown voltage, they increase the ageing of insulation liquids and dielectric paper.

The assessment of a TiO2 vegetal-based dielectric nanofluid has been carried out, and its characteristics and behavior have been tested and compared with a previously tested maghemite nanofluid. The results obtained reflect a similar affectation of the main properties, with a maximal improvement of the breakdown voltage of 33% at 0.5 kg/m3, keeping the thermal conductivity and the viscosity almost constant, especially the first one. This thermal characterization agrees with the results obtained when applying the TiO2 optimal nanofluid in the cooling of an experimental setup, with a slightly worse performance than the base fluid. Nevertheless, this performance is the opposite to that noticed with the ferrofluid, which was capable of improving the cooling of the transformer and decreasing its temperature. The similarities between the characterizations of both nanofluids, the differences in their cooling performances and their different magnetic natures seem to point out the presence of additional thermomagnetic buoyancy forces to support the improvement of the cooling.

Pinus subsección Australes es un grupo de pinos duros de América del Norte que comprende aproximadamente 29 especies de árboles importantes económicamente y ecológicamente distribuidos a lo largo de toda América del Norte y Central y las Islas Caribeñas. Estudios previos han mostrado que las especies de esta subsección a menudo comparten haplotipos de ADN de plastidio, un patrón que es atribuido a la hibridación introgresiva y la retención de polimorfismos ancestrales. Aquí describimos la diversidad de haplotipos de plastidio y la morfología para este grupo de especies en los estados de Guerrero y Oaxaca, México. Siete especies de Pinus subsección Australes son reconocidas en el área de estudio, una de las cuales, P. patulaincluye dos variedades. Siete sitios variables y nueve haplotipos fueron encontrados amplificando un fragmento de 840 p. b. de ADN de la región codificante ycf1. Se encontraron haplotipos compartidos para P. patulavar. patula, P. patula var. longipedunculata, P.herrerae y P. tecunumanii. Cuatro de los nueve haplotipos encontrados están restringidos a Oaxaca. Aunque las genealogías de genes son valiosas para estudiar la evolución de este grupo, se requieren mayor muestreo de individuos y más sitios variables para la inferencia de relaciones entre las especies.

Transformers are installed in power distribution systems to perform changes in supply voltage. Large consumers often have several transformers installed in parallel to ensure continuity of supply in the event of failure. These machines can achieve very high efficiency, but their efficiency is not constant since it depends on the power demanded at each time. Therefore, the level of efficiency that correspond to the operation of a specific transformer depends on two factors: machine technical characteristics and electrical load. In this work, the authors have proposed a methodology which shows the optimal number of transformers to be connected at each period in the substations of a large Spanish hospital, in order to achieve the maximum seasonal efficiency of these machines. The results of the energy saving are determined with respect to the current situation, in which all the transformers are permanently connected. On the other hand, the European Union has established a new regulation that sets the minimum energy efficiency requirements for new power transformers. This efficiency improvement is proposed to be applied gradually in two stages, a first limit came into force in 2015, while a more restrictive approach will appear in the year 2021. This work has also studied the potential energy savings that would occur when the substations of the hospital have more efficient transformers complying with the new European Regulation 548/2014.

El síndrome de Evans Fisher, descrito por primera vez en 1951, es un desorden autoinmune caracterizado por la presencia simultánea o secuencial de anemia hemolítica, trombocitopenia inmune y, en ocasiones, neutropenia inmune; con una prueba de antiglobulina directa positiva. Puede ser de causa primaria o secundaria a otras condiciones, como el lupus eritematoso sistémico, los síndromes linfoproliferativos o inmunodeficiencias primarias. Es muy rara su asociación con la esclerodermia. Con el término esclerodermia, que en sentido literal significa piel dura, se designa un grupo de enfermedades y síndromes que tienen como característica común la induración y el engrosamiento cutáneos. Se caracteriza por la presencia de un depósito excesivo de los componentes del tejido conjuntivo, expresado en forma de fibrosis hística, y por alteraciones estructurales del lecho vascular. Con un cuadro clínico muy amplio, afecta fundamentalmente la piel y ciertos órganos internos, como tubo digestivo, pulmón, corazón y riñón. Se presenta una paciente femenina de 75 años de edad, piel negra, con antecedentes de hipertensión arterial, diabetes mellitus tipo 2, cardiopatía isquémica y esclerodermia, esta última diagnosticada seis meses antes de su ingreso. Acudió por decaimiento marcado, palidez cutáneo-mucosa intensa y petequias generalizadas. En los estudios realizados se detectó anemia y trombocitopenia severas, reticulocitosis, prueba de antiglobulina directa positiva e hipercelularidad medular con hiperplasia severa de los sistemas megacariopoyético y eritropoyético. Se diagnosticó un síndrome de Evans Fisher y se trató con esteroides e inmunomoduladores; se logró la mejoría clínica y la remisión hematológica.

Objetivos: examinar el perfil de anticuerpos en pacientes con lupus eritematoso sistémico y establecer la correlación entre los niveles de anticuerpos y la actividad de la enfermedad y de la nefritis lúpica. Métodos: en 213 pacientes con lupus eritematoso sistémico, atendidos de forma consecutiva, se determinaron los anticuerpos anti-DNA de doble cadena (DNAdc), antinucleosoma (Nu), anti-Sm, anti-RNP, anti-Ro, anti-La y anti-Scl-70 por ensayo inmunoadsorbente ligado a enzima (ELISA), el C3 y el C4. La actividad de la enfermedad fue evaluada por el índice SLEDAI-2K, sin la contribución de anti-DNAdc, C3 ni C4. Los niveles de anticuerpos, el complemento y la actividad del lupus eritematoso sistémico fueron correlacionados. Resultados: los niveles de todos los anticuerpos resultaron superiores significativamente en los pacientes en fase activa de la enfermedad con respecto a los que se hallaban en la fase inactiva. Los coeficientes de correlación de Spearman más altos con la puntuación de SLEDAI-2K correspondieron a los anti-Nu y anti-DNAdc (p= 0,856 y p= 0,616, respectivamente, p < 0,001 para ambos). Las áreas bajo de la curva (AUC) del análisis COR de la actividad del LES fueron en orden decreciente para los anti-Nu= 0,948, anti-DNAdc= 0,810, anti-RNP= 0,705, C4= 0,704, anti-Sm= 0,703, C3= 0,688, anti-Scl-70= 0,611, anti-La= 0,601 y anti-Ro= 0,593; y de la actividad renal para los anti-Nu= 0,845, anti-DNAdc= 0,755, C4= 0,694, C3= 0,670, anti-Sm= 0,641, anti-RNP= 0,630, anti-Scl-70= 0,611, anti-Ro= 0,593 y anti-La= 0,567. Conclusión: los anticuerpos anti-Nu mostraron una capacidad discriminatoria excelente para la actividad del LES y de la actividad renal lúpica, superior a la de los anti-DNAdc y el resto de los marcadores.