Computational design of a Massive Solar-Thermal Collector enhanced with Phase Change Materials Peralta, Ignacio; Fachinotti, Victor Daniel; Koenders, Eduardus A.B.; Caggiano, Antonio A cement-based device that can meet, partially or completely, the heating loads of a building by absorbing the solar radiation and converting it into thermal energy can be defined as a Massive Solar-Thermal Collector. The absorbing material for the incoming radiation is made of a cementitious composite, generally concrete, and flowing water inside tubes acts as a heat transfer medium. For an optimized performance, during periods of solar radiation, the device has to efficiently conduct the heat flow from the absorbing surface of the collector and transfer this heat energy to the water. Then, when the radiation is reduced or became null, the device should retain as much as possible the heat energy, reducing the heat that is escaping the collector and consequently the losses to the surrounding environment. In this work, by performing a parametric analysis, different absorbing materials are tested with the objective of finding the best configuration that maximizes the energy efficiency of the collector. Cementitious materials, in combination with Phase Change Materials with distinct melting (and solidification) temperatures, are selected as candidate absorbing materials. The weather variables of an entire year and for two different locations are considered to evaluate the behavior of these devices in opposite climates. After numerical simulations, in where an enthalpy-based finite element formulation is used to solve the physical problem, the obtained results allow to conclude that the inclusion of Phase Change Materials within the absorber material of the collectors, if it is done in a correct way, can improve the energy performance of these devices. In this study, 34 °C and 53 °C are chosen as the most appropriated melting temperatures, which conduct to considerable improvements in the achieved performances, and in both warm and cold climates.

Nest-sharing behavior of captive Broad-snouted caimans (Caiman latirostris): Cooperation or exploitation? Pierini, Sofía Evelyn; Imhof, Alba; Larriera, Alejandro; Piña, Carlos Ignacio; Simoncini, Melina Soledad Communal egg-laying is not frequently observed in crocodilians that exhibit nest attendance. However, it has been reported for both wild and captive Caiman latirostris. To understand the proximate causes of communal nesting, we aim to describe the nesting behavior of caimans during communal egg-laying in a captive population. Video cameras were placed at nests and the behavior of females was monitored throughout three incubation periods. We documented and analyzed social behavioral data. Nest-sharing behavior consisted of several females congregating and performing nest construction, nest vigilance and nest maintenance. It was observed in all nests previous to egg-laying. After the first laying, one female prevented others from approaching. The second egg-laying female negatively affected the previous clutch. Working together at the same nest would appear to be an exploitative rather than a cooperative activity, and communal nesting could be a competitive interaction, due to limited suitable nesting sites or overcrowding due to captivity.

De qué lado de la mecha te encontrás: Juventudes y política en el cine argentino contemporáneo Zgaib, Jacobo Iván Este artículo busca reflexionar en torno a dos películas recientes que aparecen como excepciones dentro de los modos dominantes de retratar a las juventudes y los procesos políticos y culturales de Argentina. Tanto Camila saldrá esta noche (2021) como Ciudad Universitaria (2022) pueden entenderse como exploraciones estéticas y narrativas que toman distancia de la neutralidad y la baja intensidad que caracterizó a los dramas juveniles del cine argentino desde fines de los años ‘90.

Describir objetos fotográficos: Reflexiones y recursos para su registro en bases de datos informáticas; Describing Photographic Objects:Thoughts and Resources for Their Recording in Computer Databases Lapenda, María Agustina; Aguilar, Clara; Tomasini, Clara Agustina Este artículo aborda problemáticas detectadas en el trabajo con archivos y colecciones fotográficas tanto públicas como privadas relativas a la catalogación, gestión y acceso a la información de objetos fotográficos, a su correcta descripción y a los esquemas de metadatos y vocabulario utilizados para registrarlos. En función de esto, y mediante un enfoque interdisciplinario (archivística, humanidades, conservación, informática), ofrecemos un conjunto de recursos y lineamientos orientados a facilitar la carga y el acceso a la información relativa a documentos fotográficos, contemplando sus múltiples dimensiones y especificidades. Se presenta, además, un detalle de los antecedentes locales e internacionales que guiaron la elaboración de dichas herramientas, y se especifican algunos fundamentos y definiciones técnicas sobre las posibilidades de las bases de datos computacionales. Por último, se busca mostrar la importancia de la reflexión crítica y situada en el desarrollo e implementación de herramientas informáticas en acervos fotográficos.; This article talks about difficulties detected when working with photographic archives and collections -both public and private- related to the processes of cataloging, managing, and accessing information of photographic objects, as well as their description through metadata schemes and vocabulary. Based on the latter, and via an interdisciplinary approach (archival studies, humanities, conservation, computer science), we offer a set of resources and guidelines that aim to facilitate both registering and accessing information related to photographic documents, considering their multiple dimensions and specificities. A detail of the local and international previous efforts and works that guided the elaboration of these tools is also presented. Moreover, fundamentals and technical definitions of the possibilities of computational databases are specified. Finally, the article seeks to show the importance of critical and contextualized thinking in the development and implementation of computer tools in photographic collections.

Looking under stones: A new Ctenomys species from the rocky foothills of the Sierras Grandes of central Argentina Mapelli, Fernando Javier; Teta, Pablo Vicente; Contreras, Facundo; Pereyra Villaurreta, Maria Daniela Renée; Priotto, Jose Waldemar; Coda, José Antonio Ctenomys (tuco-tucos) is one of the most speciose genera of mammals, and the number of species that compose it continues to increase. Of the 65 species currently recognized for the genus, 15% have been described in the last 10 years. In this work, based on morphological and molecular evidence, we describe a new species of tuco-tuco for Central Argentina. This new species inhabits stony soils in the foothills of Sierras Grandes in Córdoba province and is distinguished from its congeners by a combination of anatomical characters, including a unique morphology of the posterolateral extension of the palatine. The molecular phylogeny based on the mitochondrial cytochrome b gene showed that this new species does not belong to any species complex described for Ctenomys. On the contrary, this new taxon shows a high genetic divergence with the rest of the species and species groups of Ctenomys and was recovered as an independent lineage within the phylogeny of the genus. This finding increases the richness of Ctenomys to 66 species. Our results highlight the need to increase the geographic sampling of studies in this genus to achieve a more complete understanding of its diversity.

"A la vuelta de mi casa había un transa”: de la implicación de adolescentes varones con el narcotráfico hacia el mapeo del crimen organizado en el Gran Buenos Aires, Argentina; "Around the corner, there was a drug dealer": from the involvement of male adolescents in drug trafficking towards a methodological proposal for the mapping of organized crime in Greater Buenos Aires, Argentina Rocha, Heder Leandro En este trabajo presento una propuesta metodológica para el mapeo del narcotráfico en el Gran Buenos Aires, Argentina. Es una aproximación, no definitiva y “de abajo para arriba”. Es decir, sale del eslabón más “bajo” del narcotráfico para conocer las estructuras superiores. Utilizo 13 entrevistas en profundidad con jóvenes y adolescentes residentes del Gran Buenos Aires y que en noviembre de 2017 estaban bajo tratamiento por consumo de drogas en una comunidad terapéutica de Lomas de Zamora. La metodología utilizada sistematiza en una red semántica y en un mapa síntesis los relatos de interacción con el narcotráfico, reconstruyendo así algunas formas de espacialización, algunas relaciones de poder de su jerarquía interna y algunos de sus actores. Por fin, el esfuerzo desagua en una metodología capaz de iluminar el accionar espacial de otras actividades del crimen organizado como el tráfico de armas y la trata de personas.; In this article, I present a methodological proposal for the mapping of drug trafficking in Greater Buenos Aires, Argentina. It is a non-definitive, bottom-up approximation. In other words, it rises from the 'lowest' rung of drug trafficking to gain knowledge about the higher structures. I use 13 indepth interviews with young people and adolescents residing in Greater Buenos Aires who in November 2017 were undergoing treatment for problematic drug use in a therapeutic community in Lomas de Zamora. e methodology used systematizes the stories of interaction with drug trafficking in a semantic network and a synthesis map, thus reconstructing some forms of spatialization, some power relations in its internal hierarchy, and some of its actors. Finally, the effort culminates in a methodology which can illuminate the spatial action of other organized crime activities such as arms trafficking and human trafficking.

Development of new 1, 3-dihydroxyacridone derivatives as Akt pathway inhibitors in skeletal muscle cells Irazoqui, Ana Paula; Menéndez, Cintia Anabella; Steingruber, Sebastián; González, Agustina; Appignanesi, Gustavo Adrian; Buitrago, Claudia Graciela; Gerbino, Darío César In the present work, four new compounds based on the privileged structure acridone were efficiently synthesized following simple operational techniques and biologically tested on proliferative skeletal muscle cells (C2C12) and rhabdomyosarcoma cells (RD) showing no significant changes in the number of dead or viable cells at 1 µM during 24 or 48 h of treatment. Of relevance, acridone derivatives 3a-3d at 0.5 µM for 24 h effectively inhibited Akt activation in C2C12, while at 1 µM only compounds 3a and 3b have effect. RD cells showed a different response pattern. These cells treated with 3a (0.5 µM), 3b (0.5 µM) or 3d (0.5 or 1 µM) for 24 h shown significant Akt inhibition. In addition, 3a-3d assayed at 1 µM for 48 h were highly successful in inhibiting Akt phosphorylation. Finally, based on molecular docking and molecular dynamics simulations, we rationalize the experimental results mentioned above and propose that 3-phosphoinositide-dependent kinase-1 (PDK1) could be one of the molecular targets of this new series of 1, 3-dihydroxyacridone derivatives. Biological and in silico studies revealed that 3b could be considered as the most promising prototype for the development of new antitumor agents.

Hongos colectados en el sur de Argentina Ejemplares colectado por MATTHEW SMITH e investigadores locales durante las campañas de colecta realizadas en el sur Argentino, durante los años 2015-2016. Producto de un proyecto en conjunto entre el IMBIV y el Herbario de la Universidad de Florida.

First records of Anthopleura nigrescens (Verrill, 1928) and Telmatactis panamensis (Verrill, 1869) (Cnidaria, Anthozoa, Actiniaria) in the Coiba National Park, Pacific coast of Panama Acuña, Fabian Horacio; González Muñoz, Ricardo Enrique; Garese, Agustin; Díaz Ferguson, Edgardo We report two species of sea anemones, Anthopleura nigrescens (Verrill, 1928) and Telmatactis panamensis (Verrill, 1869), for the first time from Parque Nacional Coiba, a large, protected area in the Pacific off Panama. In addition, we describe the external anatomical taxonomic characters and provide images of live specimens of each species. The number of sea anemones species known for Panama is updated to 57. This work constitutes the first study in the documentation of sea anemones of Coiba Island.

GEMA—An Automatic Segmentation Method for Real-Time Analysis of Mammalian Cell Growth in Microfluidic Devices Isa Jara, Ramiro Fernando; Pérez Sosa, Camilo José; Macote Yparraguirre, Erick Leonel; Revollo Sarmiento, Natalia Veronica; Lerner, Betiana; Miriuka, Santiago Gabriel; Delrieux, Claudio Augusto; Pérez, Maximiliano; Mertelsmann, Roland Nowadays, image analysis has a relevant role in most scientific and research areas. This process is used to extract and understand information from images to obtain a model, knowledge, and rules in the decision process. In the case of biological areas, images are acquired to describe the behavior of a biological agent in time such as cells using a mathematical and computational approach to generate a system with automatic control. In this paper, MCF7 cells are used to model their growth and death when they have been injected with a drug. These mammalian cells allow understanding of behavior, gene expression, and drug resistance to breast cancer. For this, an automatic segmentation method called GEMA is presented to analyze the apoptosis and confluence stages of culture by measuring the increase or decrease of the image area occupied by cells in microfluidic devices. In vitro, the biological experiments can be analyzed through a sequence of images taken at specific intervals of time. To automate the image segmentation, the proposed algorithm is based on a Gabor filter, a coefficient of variation (CV), and linear regression. This allows the processing of images in real time during the evolution of biological experiments. Moreover, GEMA has been compared with another three representative methods such as gold standard (manual segmentation), morphological gradient, and a semi-automatic algorithm using FIJI. The experiments show promising results, due to the proposed algorithm achieving an accuracy above 90% and a lower computation time because it requires on average 1 s to process each image. This makes it suitable for image-based real-time automatization of biological lab-on-a-chip experiments.

Mujeres y política: Antiperonismo y moralidad sexual en Argentina (1946- 1952); Women and politics: Anti-peronism and sexual morality in Argentina (1946-1952) Perrig, Sara Angélica El presente artículo estudia el posicionamiento político de mujeres opositoras al gobierno de Juan Domingo Perón en Argentina (1946-1952) que participaban de las diferentes fuerzas partidarias de la época. Por un lado, analiza el modo en que estas desarrollaron un pensamiento sobre las mujeres y su inserción política atravesado por contradicciones y paradojas propias de los reclamos históricos por sus derechos. Por otro lado, aborda cómo las antiperonistas recurrían a una moralidad sexual tradicional para oponerse al peronismo, la misma que actuaba en las bases de su opresión y subordinación respecto a los hombres. Finalmente, el artículo sostiene que, a pesar de estar atravesadas por los obstáculos de pensar(se) desde un lugar de dominación, las mujeres participaron activamente de la esfera pública-política y reflexionaron sobre la incursión femenina en un ámbito masculinizado.

Reducing Operational Expenses of LoRaWAN-Based Internet of Remote Things Applications Finochietto, Mariano; Santos, Rodrigo Martin; Ochoa, Sergio F.; Meseguer, Roc LoRaWAN has become the most widely used low-power wide-area network technology to implement monitoring solutions based on the Internet of remote things (IoRT) paradigm. Typically, these solutions interconnect remote sensing areas and data processing infrastructure located in urban centers. The operation expenses of these solutions depend mainly on the traffic sent through the network backhaul, i.e., the link that connects the remote sensing area and the urban area where the data are usually processed and stored. This service is provided by telecommunication companies and represents the main operation cost of IoRT solutions. These expenses usually limit the affordability of IoRT-based systems in developing countries, and also in scenarios where the operational cost is an issue to address. This paper presents an extension to the LoRaWAN protocol, named Node-Aware-LoRaWAN (NA-LoRaWAN), that reduces the traffic in the backhaul, thus decreasing the operational expenses of IoRT-based systems. In order to evaluate the performance of NA-LoRaWAN, it was compared to a regular LoRaWAN implementation. Depending on the network scenario, the proposed extension reduced the traffic through the backhaul in the range of 12–34%. This extension opens several opportunities to use IoRT solutions in application domains with a low operational budget, e.g., precision agriculture, environmental monitoring and natural hazards’ early detection.

La Incidencia De La Variabilidad Pluviométrica Sobre La Hidroquímica Y El Riesgo Sanitario Potencial De Los Contaminantes Naturales En Una Cuenca Endorreica Del Sur De La Llanura Pampeana; Incidence Of Rainfall Variability On Hydrochemistry And The Potential Health Risk Of Natural Pollutants In An Endorheic Basin Of The Southern Pampean Plain Espósito, Martín Eduardo; Fernández, Sandra Noemí; Brandizi, Laura Daniela; Parodi, Elisa Rosalia A variabilidade das precipitações modifica a presença dos contaminantes naturais (As – F) dos recursos hídricos, deixando importante porcentagem de habitantes da zona rural e da periferia urbana exposta ao desenvolvimento de enfermidades. O objetivo é analizar a variação hidroquímica producida pelas variação das precipitações e determinar o risco sanitário potencial causado pela ingestão e contato dérmico com a água. Na bacia da Laguna de Puan se extraíram dez amostras de água em diferentes períodos pluviométricos durante três anos, para fins de determinação de valores As-F e realização de análises de risco à saúde. A profundidade do lençol freático foi determinada para estudar a hidrodinâmica. Todas as variáveis foram analisadas estatisticamente. Em um período de baixa pluviosidade, as concentrações do par As-F aumentam nas águas subterrâneas utilizadas para consumo humano, estabelecendo que a presença de As representa um alto risco à saúde das pessoas, ao contrário de F. A água da lagoa não é adequada para consumo humano e não representa risco devido ao contato com a pele para a saúde da população que pratica esportes aquáticos; The rainfall variability modifies the presence of natural pollutants (As-F) in this water resource, leaving a significant percentage of rural and peri-urban inhabitants exposed to the development of diseases. The objective is to analyze the hydrochemical variation produced by rainfalls and determine the potential health risk caused by ingestion and dermal contact of water. In order to determine the As-F values and perform health risk analyses, ten water samples were extracted from the Puán lagoon basin in different rainfall periods for 3 years. The water table depth was determined in order to study the hydrodynamics. All variables were analyzed statistically. In a period of low rainfall, the As-F concentrations in groundwater for human consumption increase, showing that the presence of As represents a high health risk for people, unlike F. The water in the lagoon is unfit for human consumption, and does not represent a risk due to dermal contact for the health of those who play water sports

IAPT chromosome data 36 Rodriguez Mata, Orlando Abrahan; Gianini Aquino, Analía Cecilia; Daviña, Julio Rubén; Honfi, Ana Isabel AMARYLLIDACEAE. Habranthus cardenasianus Traub & I. S. Nelson, 2n = 24; Argentina, Salta, 10 Oct 2013, D 666 (MNES). The karyotypic formula consists in 12 metacentric (m) and 12 submetacentric (sm) chromosomes (Fig. 3). The genomic size is 213.73 µm. Fluorescent in situ hybridization showed the hybridization sites of the ribosomal DNA probes. The presence of active ribosomal genes (rDNA 18S / 26S) was located on the short arm of chromosomes 9 and 10 (m), on the long arm of chromosome 1 (m) and on the short arm of submetacentric chromosomes 23 and 24.

Oxidation of α-Trifluoromethyl and Nonfluorinated Secondary Alcohols to Ketones Using a Nitroxide Catalyst Politano, Fabrizio; Brydon, William P.; Leadbeater, Nicholas E. A methodology for the oxidation of E-trifluoromethyl alcohols to the corresponding trifluoromethyl ketones is presented. A catalytic quantity of a nitroxide is used, and potassium persulfate serves as the terminal oxidant. The methodology proves effective for aromatic, heteroaromatic, and conjugated alcohol substrates. It can be extended to nonfluorinated secondary alcohols and, in this case, can be applied to a range of aromatic, heteroaromatic, and aliphatic alcohols.

Cuerpos, emociones, temporalidades y espacialidades del personal de salud durante la pandemia del COVID 19; Bodies, emotions, temporalities and spatialities of health personnel during the COVID 19 pandemic Alzina, Pilar Mercedes; Danel, Paula Mara; Favero Avico, Agustina Maria El propósito de este artículo es compartir algunas reflexiones sobre las corporalidades y las emociones del personal de salud durante la pandemia del COVID19 en el período marzo 2020 hasta mayo 2021, momento en que se realizó la primer tanda de entrevistas semiestructuradas a 15 profesionales de la salud de todas las regiones del país, en el marco de la Red del Estudio Nacional Colaborativo de Representaciones sobre la Pandemia en Argentina (ENCResPA). El artículo inicia con una introducción que explicita el objetivo del trabajo. En un segundo momento se presenta un apartado metodológico con los criterios elegidos para conformar la muestra cualitativa y la fundamentación teórico - metodológica. En la tercera parte se describen los antecedentes teóricos desde el giro afectivo y los empíricos del tema desarrollado. En la cuarta parte, se describen las percepciones del uso del tiempo y del espacio por parte del personal de salud, en el ámbito familiar y laboral. En la quinta parte se describieron los temores sobre el contagio del COVID 19 y los conflictos que surgieron en el espacio laboral y familiar en el período analizado. Hacia al final, en el sexto apartado, describe cómo se proyectaba el personal de salud para 2022. A modo de cierre, esbozans algunos interrogantes que nos interpelan a seguir reflexionando en torno a los objetivos propuestos.; The purpose of this article is to share some reflections on the corporalities and emotions of health personnel during the COVID19 pandemic in the period from March 2020 to May 2021, when the first round of semi-structured interviews was conducted with 15 health professionals. from all regions of the country, within the framework of the Network of the National Collaborative Study of Representations on the Pandemic in Argentina (ENCResPA). The article begins with an introduction that explains the objective of the work. In a second moment, a methodological section is presented with the criteria chosen to form the qualitative sample and the theoretical-methodological foundation. The third part describes the theoretical background from the affective and empirical background of the topic developed. The fourth part describes the perceptions of the use of time and space by health personnel, in the family and work environment. In the fifth part, the fears about the spread of COVID 19 and the conflicts that arose in the work and family space in the analyzed period were described. Towards the end, in the sixth section, we will describe how the health workforce was projected for 2022. By way of closing, we will outline some questions that challenge us to continue reflecting on the proposed objectives.

Integration of mark–recapture and acoustic detections for unbiased population estimation in animal communities Jarrett, Crinan; Haydon, Daniel T.; Morales, Juan Manuel; Ferreira, Diogo F.; Forzi, Francis Alemanji; Welch, Andreanna J.; Powell, Luke L.; Matthiopoulos, Jason Abundance estimation methods that combine several types of data are becoming increasingly common because they yield more accurate and precise parameter estimates and predictions than are possible from a single data source. These beneficial effects result from increasing sample size (through data pooling) and complementarity between different data types. Here, we test whether integrating mark–recapture data with passive acoustic detections into a joint likelihood improves estimates of population size in a multi-guild community. We compared the integrated model to a mark–recapture-only model using simulated data first and then using a data set of mist-net captures and acoustic recordings from an Afrotropical agroforest bird community. The integrated model with simulated data improved accuracy and precision of estimated population size and detection parameters. When applied to field data, the integrated model was able to produce, for each bird guild, ecologically plausible estimates of population size and detection parameters, with more precision compared with the mark–recapture model. Overall, our results show that adding acoustic data to mark–recapture analyses improves estimates of population size. With the increasing availability of acoustic recording devices, this data collection technique could readily be added to routine field protocols, leading to a cost-efficient improvement of traditional mark–recapture population estimation.

Paranasal sinus system and upper respiratory tract evolution in Mesozoic pelagic crocodylomorphs Cowgill, Thomas; Young, Mark T.; Schwab, Julia A.; Walsh, Stig; Witmer, Lawrence; Herrera, Laura Yanina; Dollman, Kathleen N.; Choiniere, Jonah N.; Brusatte, Stephen L. Thalattosuchians were a predominately marine clade of Mesozoic crocodylomorphs, including semi-aquatic teleosauroid and obligately pelagic metriorhynchid subclades. Recent advances in our understanding of thalattosuchian endocranial anatomy have revealed new details of the evolutionary transition from terrestrial to marine to pelagic taxa. Paranasal sinuses, however, have received little attention. Herein, we investigate the evolution of the paranasal sinus system and part of the upper respiratory system (nasopharyngeal ducts) in Thalattosuchia, by reconstructing the nasal and paranasal anatomy in CT scans of seven thalattosuchian skulls: one teleosauroid, two basal metriorhynchoids and four metriorhynchids. Our outgroups were: three extant crocodylian species (including adult and subadult skulls) and the basal crocodyliform Protosuchus. We found thalattosuchians exhibit exceptionally reduced paranasal sinus systems, solely comprising the antorbital sinus, as has been previously proposed. The semi-aquatic basal thalattosuchians Palgiopthalmosuchus gracilirostris and Pelagosaurus typus both have an antorbital sinus partially located medial to a reduced external antorbital fenestra and broadly communicating with the dorsal alveolar canal. In pelagic metriorhynchids, the antorbital cavity is more extensive than in basal taxa and possibly had an active function associated with a hypothesized accessory suborbital diverticulum, but our reconstructions are insufficient to confirm or reject the presence of such a diverticulum. The nasopharyngeal ducts of metriorhynchids are dorsoventrally enlarged, possibly enabling stronger ventilation. The sequence of acquisition of craniofacial adaptations show a mosaic pattern and appears to predate many skeletal adaptations, suggesting these changes occurred early in the thalattosuchian marine transition.

Violacein and its antifungal activity: comments and potentialities Durán, N.; Castro, Guillermo Raul; Portela, R. W. D.; Fávaro, W. J.; Durán, M.; Tasic, L.; Nakazato, G. Violacein is an important natural antimicrobial pigment that is mainly produced by Chromobacterium violaceum and Janthinobacterium lividum. It presents a significant range of effects against phytopathogenic and human fungi, besides being featured as having low toxicity, and by its important ecological role in protecting amphibian species and applications in dyed medical fabric. The hypothesis about violacein's action mechanisms against mucormycosis (Rhizopus arrhizus) and candidiasis (Candida auris) is herein discussed based on data available in the scientific literature.

Shocks in the Outflow of the RS Oph 2021 Eruption Observed with X-Ray Gratings Orio, Marina; Behar, E.; Luna, Gerardo Juan Manuel; Drake, J. J.; Gallagher, J.; Nichols, J. S.; Ness, J. U.; Dobrotka, A.; Mikolajewska, J.; Della Valle, M.; Ignace, R.; Rahin, R. The 2021 outburst of the symbiotic recurrent nova RS Oph was observed with the Chandra High Energy Transmission Gratings (HETG) on day 18 after optical maximum and with XMM-Newton and its Reflection Grating Spectrographs (RGS) on day 21, before the supersoft X-ray source emerged and when the emission was due to shocked ejecta. The absorbed flux in the HETG 1.3-31 Å range was 2.6 × 10-10 erg cm-2 s-1, three orders of magnitude lower than the γ-ray flux measured on the same date. The spectra are well fitted with two components of thermal plasma in collisional ionization equilibrium, one at a temperature ≃ 0.75 keV and the other at a temperature in the 2.5-3.4 keV range. With the RGS we measured an average flux of 1.53 × 10-10 erg cm-2 s-1 in the 5-35 Å range, but the flux in the continuum and especially in the lines in the 23-35 Å range decreased during the 50 ks RGS exposure by almost 10%, indicating short-term variability on a timescale of hours. The RGS spectrum can be fitted with three thermal components, respectively at plasma temperatures between 70 and 150 eV, 0.64 keV, and 2.4 keV. The post-maximum epochs of the exposures fall between those of two grating spectra observed in the 2006 eruption on days 14 and 26: they are consistent with a similar spectral evolution, but in 2021 cooling seems to have been more rapid. Iron is depleted in the ejecta with respect to solar values, while nitrogen is enhanced.