Bioplastics are revolutionizing the packaging industry Ehman, Nanci Vanesa; Area, Maria Cristina The production of bioplastics is a growing trend. The utilization of renewable sources, in some cases currently wasted, to replace petroleum derivatives, is providing opportunities to achieve more environmentally friendly product life cycles. The possibility of producing biodegradable products under normal environmental conditions is another goal of recent studies. This editorial summarizes current aspects in the production of bioplastics. We highlight new studies that make it possible to obtain biodegradable composites using a natural, renewable, high availability, and low-cost material, such as cellulose.

Quasi-bifurcation and Imperfection-sensitivity of Cylindrical Shells under Pressures due to an Explosion Ameijeiras, Mariano Pablo; Godoy, Luis Augusto The static and dynamic behavior of a horizontal cylindrical shell (as used to store fuels in tanks) is investigated in this work by means of computational modeling. Under a distributed pressure commonly used to model effects due to explosions, the geometrically nonlinear behavior is explored to identify bifurcation and limit points along the static equilibrium path, and the associated displacements. Critical load reductions due to imperfections are found in the order of 25%. The dynamic analysis is next presented to identify the possibility of reaching a quasi-bifurcation. It is found that the first peak in the transient response at which the displacement reaches the same value as in the limit static case occurs for a load which is about 3.5 times the static bifurcation load. The velocity is zero at this state and is identified as a quasi-bifurcation, at which the shell is expected to display a static instability. Imperfection-sensitivity of the quasi-bifurcation load is found to be of the same order as the static one. This is the first quasi-bifurcation study of a shell to identify dynamic buckling due to a nearby explosion.

Potentials of constrained sliding mode control as an intervention guide to manage COVID19 spread Nuñez, Sebastián; Inthamoussou, Fernando Ariel; Valenciaga, Fernando; Garelli, Fabricio This work evaluates the potential of using sliding mode reference conditioning (SMRC) techniques as a guide for non-pharmaceutical intervention (NPI) to control the COVID-19 pandemic. In particular, for the epidemiological problem addressed here, it is used to compute the contact rate reduction requirement in order to limit the infectious population to a given threshold. The SMRC controller allows the desired output variable limit and its approaching rate to be tuned explicitly. Implementation issues are taken into account and a periodically update of the NPI is proposed for the real life application. The strategy is evaluated under different scenarios where its distinctive features are exhibited.

Afrontamiento docente en tiempos de COVID-19; Teacher coping strategies in times of COVID-19; Enfrentamento de professores em tempos de covid-19 Marsollier, Roxana Graciela; Expósito, Cristián David INTRODUCCIÓN. Las personas enfrentan cotidianamente en el mundo del trabajo distintas situaciones que pueden ser estresantes y conflictivas. Frente a ellas, desarrollan determinados pensamientos o acciones para eliminar los estresores externos o bien mitigar sus efectos. En tiempos de pandemia, las estrategias de afrontamiento desarrolladas por las personas han sido cruciales en su manera de posicionarse ante la crisis y hacer frente a la situación. OBJETIVO. La presente investigación tiene por finalidad indagar sobre las estrategias de afrontamiento utilizadas por los docentes frente al desafío que presenta la enseñanza virtual en situación de confinamiento social a causa de la pandemia por COVID-19 durante el año 2020. MÉTODO. Se trabajó con una muestra intencional de docentes y directivos (n=777) de instituciones de distintos niveles educativos de Mendoza, Argentina. Se aplicó la prueba psicométrica Brief COPE-28 sobre afrontamiento y se evaluaron otras variables de base y contextuales. RESULTADOS. Los resultados indican que ante la situación de crisis predomina un estilo de afrontamiento efectivo o funcional, mediante el uso de estrategias de afrontamiento activo, aceptación, planificación y reinterpretación positiva, entre las más señaladas. DISCUSIÓN Y CONCLUSIONES. Los hallazgos obtenidos impulsan a seguir investigando las complejas consecuencias educativas acaecidas durante esta pandemia. A su vez, invitan a generar nuevas acciones de intervención orientadas al fortalecimiento de estrategias efectivas que mitiguen el impacto de los riesgos psicosociales emergentes.; INTRODUCTION. People live every day in the world of work in situations that can be stressful and conflictive. This leads people to develop certain thoughts or actions to eliminate external stressors or mitigate their effects. In times of pandemic, the coping strategies developed by people have been crucial to position themselves in the face of the crisis and coping the situation. OBJECTIVE. The objective of this study is to research the coping strategies used by teachers in the face of the challenge presented by virtual teaching in a situation of social confinement due to the COVID-19 pandemic, in 2020. METHOD. We worked with an intentional sample of teachers and directors (n=777) of institutions of different educational levels in Mendoza, Argentina. The Brief COPE-28 psychometric test on coping strategies was applied and other sociodemographic variables were evaluated. RESULTS. The results indicate that in the face of the crisis situation, an effective or functional coping style predominates, through the use of active coping strategies, acceptance, planning and positive reinterpretation, among the most indicated. DISCUSSION AND CONCLUSIONS. The results obtained encourage further investigation of the complex educational consequences that occurred during this pandemic. In turn, they invite the generation of new intervention actions aimed at strengthening effective strategies that mitigate the impact of emerging psychosocial risks.

Evaluation of a physiologically based model to predict Dalbulus maidis occurrence in maize crops: validation in two different subtropical areas of South America Rossini. Luca; Virla, Eduardo Gabriel; Luft Albarracin, Erica Beatriz; Van Nieuwenhove, Guido Alejandro; Speranza, Stefano The maize leafhopper, Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae), is a specialist herbivore that develops on maize plants (Zea mays L., Poaceae). Every year, it is responsible for considerable reductions in yields of the maize fields of the Americas, because alongside its direct damages it is also a vector of three relevant plant pathogens. The transmitted diseases come to have a high incidence, resulting in significant yield losses, thereby forcing farmers and technicians to attempt a tight control of the fields mostly using non-specific insecticides. Decision support systems based on mathematical models may be valuable in helping to reduce the use of agrochemicals in this regard, as they can provide a projection of the future situation based on past and present data. With this precondition, this work aims to apply and validate a physiologically based model to describe populations of D. maidis developing in two experimental fields located in Argentina, which are characterised by different climatic conditions. Experimentation in the two fields involved a 3-year survey during the growing seasons 2009, 2010, and 2011, where the adult populations of maize leafhoppers were monitored from the sowing of maize plants to the end of the phenological stage at which they are most susceptible to D. maidis activity. Results showed a good response of the model in describing maize leafhopper populations, also allowing the possibility of setting a threshold for intervention and a projection of the situation if any control action is applied.

Screening methods for isolation of biocontrol epiphytic yeasts against penicillium digitatum in lemons Pereyra, Martina María; Diaz, Mariana Andrea; Soliz Santander, Fabricio Fabián; Poehlein, Anja; Meinhardt, Friedhelm; Daniel, Rolf; Dib, Julian Rafael Worldwide, the green rot caused by Penicillium digitatum is one of the most aggressive postharvest diseases of lemons. Searching for sustainable alternatives to chemical fungicides, epi-phytic yeasts as potential biocontrol agents were isolated from citrus fruits using a tailor-made selective medium. For disclosing their antagonistic potential against P. digitatum, obtained isolates were subjected to direct screening methods, both in vitro and in vivo. In the course of the primary in vitro screening that comprised dual culture assays, 43 yeast strains displaying antagonistic activities against the pathogen were selected. Subsequently, such strains were subjected to an in vivo screening that consisted of a microscale test, allowing the selection of six yeast strains for further analysis. In the final screening using macroscale in vivo tests, three strains (AcL2, AgL21, and AgL2) displaying the highest efficiencies to control P. digitatum were identified. The protection efficiencies in lemons were 80 (AcL2), 76.7 (AgL21), and 75% (AgL2). Based on sequence analysis of the PCR amplified D1/D2 domains of the 26S rRNA genes, they were identified as representatives of the species Clavispora lusitaniae. Interestingly, the strains exhibited a broad action spectrum among citrus fruits as they were also able to combat the green mold disease in grapefruit and two orange varieties. The direct screening methods applied in this study favored the recovery of effi-cient candidates for application as biological control agents to combat fungal infestations of citrus fruits.

Houssay en su boda con María Angélica Catán Bernardo Houssay en su boda con la Dra. María Angélica Catán, junto a dos personas. Fotografía gentileza del Banco de Imágenes de la Biblioteca Central de la Facultad de Medicina de la Universidad de Buenos Aires. Base de datos: CPA, id 004

Houssay en la cátedra de Fisiología de Facultad de Ciencias Médicas de la Universidad de Buenos Aires Gentileza del Archivo General de la Nación, AR-AGN-AGAS01- Caja 590 - Inventario 87584.

Distintas ediciones del libro Fisiología Humana de Houssay A la izquierda, en azul-violeta la primera edición del libro que data de 1945, cuyos autores fueron Houssay, Lewis, Orías, Braun Menéndez, Hug y Foglia. En la 2da. edición en español (color rojo) del año 1950, participa Luis Leloir como co-autor. En otra edición en español (color naranja) Caldeyro-Barcia, Covián, Fasciolo; Alberto B. Houssay, L. de Soldati. La obra fue parte de la bibliografía usada para la formación de generaciones de médicos en Argentina y tuvo trascendencia internacional, fue traducida a distintos idiomas como ingles, francés, portugués, griego, italiano, tamil, sinhala.

Instituto de Biología y Medicina Experimental: hall central Vista del hall central de la sede del IBYME en la calle Costa Rica 4185, Palermo, Buenos Aires, fue la primera sede del Instituto en el año 1944.

Instituto de Biología y Medicina Experimental: vista de un laboratorio (I) Vista de uno de los laboratorios en la primera sede del Instituto, en la calle Costa Rica 4185 del barrio de Palermo en Buenos Aires.

Instituto de Biología y Medicina Experimental: Vista de un laboratorio (II) Vista de uno de los laboratorios en la primera sede del Instituto, en la calle Costa Rica 4185 del barrio de Palermo en Buenos Aires.

Instituto de Biología y Medicina Experimental: vista exterior El Instituto de Biología y Medicina Experimental en su primera sede en la calle Costa Rica 4185, Palermo, Buenos Aires. Año 1944.

Bernardo Houssay, retrato Bernardo Houssay de pie, lleva guardapolvos y las manos en los bolsillos. Plano medio largo. año 194?. Una copia de esta fotografía se usó como portada de Acta Physiológica Latinoamericana en el año 1971.

Houssay de vacaciones en familia en Mar del Plata No especifica Houssay con su familia de vacaciones en Mar del Plata. Gentileza del Banco de Imágenes de la Biblioteca Central de la Facultad de Medicina de la Universidad de Buenos Aires. Base de datos: CPA, id. 007

Houssay con su familia de vacaciones No especifica Bernardo Houssay con su mujer, María Angélica Catán y sus tres hijos en la playa. Fotografía gentiteleza de la Casa Museo Houssay-FECIC.

Bernardo Houssay a los 13 años Houssay a los 13 años. Plano medio corto. A esa edad Bernardo finalizó el bachillerato. Fotografía gentileza de la Dra. Patricia Saragüeta. Original conservado en la la Casa Museo Houssay-FECIC.

Mixed methods for degenerate elliptic problems and application to fractional Laplacian Cejas, María Eugenia; Duran, Ricardo Guillermo; Prieto, Mariana Ines We analyze the approximation by mixed finite element methods of solutions of equations of the form −div (a∇u) = g, where the coefficient a = a(x) can degenerate going to zero or infinity. First, we extend the classic error analysis to this case provided that the coefficient a belongs to the Muckenhoupt class A2. The analysis developed applies to general mixed finite element spaces satisfying the standard commutative diagram property, whenever some stability and interpolation error estimates are valid in weighted norms. Next, we consider in detail the case of Raviart–Thomas spaces of arbitrary order, obtaining optimal order error estimates for simplicial elements in any dimension and for convex quadrilateral elements in the two dimensional case, in both cases under a regularity assumption on the family of meshes. For the lowest order case we show that the regularity assumption can be removed and prove anisotropic error estimates which are of interest in problems with boundary layers. Finally we apply the results to a problem arising in the solution of the fractional Laplace equation.

Computational model for membrane transporters: Potential implications for cancer Carusela, María Florencia; Rubi, J. Miguel To explain the increased transport of nutrients and metabolites and to control the movement of drug molecules through the transporters to the cancer cells, it is important to understand the exact mechanism of their structure and activity, as well as their biological and physical characteristics. We propose a computational model that reproduces the functionality of membrane transporters by quantifying the flow of substrates through the cell membrane. The model identifies the force induced by conformational changes of the transporter due to hydrolysis of ATP, in ABC transporters, or by an electrochemical gradient of ions, in secondary transporters. The transport rate is computed by averaging the velocity generated by the force along the paths followed by the substrates. The results obtained are in accordance with the experiments. The model provides an overall framework for analyzing the membrane transport proteins that regulate the flows of ions, nutrients and other molecules across the cell membranes, and their activities.

Evaluation of viral concentration methods for SARS-CoV-2 recovery from wastewaters Barril, Patricia Angelica; Pianciola, Luis Alfredo; Mazzeo, Melina; Ousset, Maria Julia; Jaureguiberry, María Virginia; Alessandrello, Mauricio; Sanchez, Gloria; Oteiza, Juan Martín Wastewater-based epidemiology (WBE) is a useful tool that has the potential to act as a complementary approach to monitor the presence of SARS-CoV-2 in the community and as an early alarm system for COVID-19 outbreak. Many studies reported low concentrations of SARS-CoV-2 in sewage and also revealed the need for methodological validation for enveloped viruses concentration in wastewater. The aim of this study was to evaluate different methodologies for the concentration of viruses in wastewaters and to select and improve an option that maximizes the recovery of SARS-CoV-2. A total of 11 concentration techniques based on different principles were evaluated: adsorption-elution protocols with negatively charged membranes followed by polyethylene glycol (PEG) precipitation (Methods 1-2), PEG precipitation (Methods 3-7), aluminum polychloride (PAC) flocculation (Method 8), ultrafiltration (Method 9), skim milk flocculation (Method 10) and adsorption-elution with negatively charged membrane followed by ultrafiltration (Method 11). To evaluate the performance of these concentration techniques, feline calicivirus (FCV) was used as a process control in order to avoid the risk associated with handling SARS-CoV-2. Two protocols, one based on PEG precipitation and the other on PAC flocculation, showed high efficiency for FCV recovery from wastewater (62.2 % and 45.0 %, respectively). These two methods were then tested for the specific recovery of SARS-CoV-2. Both techniques could recover SARS-CoV-2 from wastewater, PAC flocculation showed a lower limit of detection (4.3 × 102 GC/mL) than PEG precipitation (4.3 × 103 GC/mL). This work provides a critical overview of current methods used for virus concentration in wastewaters and the analysis of sensitivity for the specific recovery of SARS-CoV-2 in sewage. The data obtained here highlights the viability of WBE for the surveillance of COVID-19 infections in the community.