Divulgación de la ciencia para niños a través de revistas producidas en México: aproximación a partir de las estrategias editoriales y discursivas

El discurso de la divulgación de la ciencia para niños en revistas, sus productores y sus pretensiones son los objetos y sujetos que se observan a lo largo de esta investigación, desde la perspectiva de producción del medio. Se indaga en el interior de las revistas y se establece un diálogo con sus productores, con el fin de conocer el proceso de selección de los temas a publicar y los tratamientos que se les da a éstos, y de entender cómo el discurso sobre la ciencia toma forma antes de llegar a su público meta. El proyecto parte del supuesto de que, con la publicación de revistas de divulgación científica para niños, se pretende incidir positivamente en los procesos de aprendizaje, pensamiento crítico y educación informal de sus lectores

Rammed earth walls in Mediterranean climate: material characterization and thermal behaviour

Rammed earth is considered a very sustainable construction system due to its low embodied energy, long service life and high recyclability. However, authors found that there is a lack of experimental results at real scale regarding rammed earth thermal behaviour. For this reason, this paper is first focused on the characterization of two different types of earth in order to check the suitability of being used in rammed earth walls. After the characterization, two experimental cubicle-shape buildings were built in Barcelona and Puigverd de Lleida (Spain) in order to test the thermal behaviour of their walls in two different climatic conditions. Temperature profiles inside walls have been monitored using thermocouples and temperature profile of southern walls was analysed in free floating conditions during summer and winter periods of 2013. Results show that thermal amplitude from outside to inside temperatures are decreased by rammed earth walls, achieving constant temperatures in inner surface of southern walls.Peer ReviewedPostprint (published version

Overexpression of FurA in Anabaena sp. PCC 7120 Reveals New Targets for This Regulator Involved in Photosynthesis, Iron Uptake and Cellular Morphology

Previous genomic analyses of the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 have identified three ferric uptake regulator (Fur) homologs with low sequence identities and probably different functions in the cell. FurA is a constitutive protein that shares the highest homology with Fur from heterotrophic bacteria and appears to be essential for invitro growth. In this study, we have analysed the effects of FurA overexpression on the Anabaena sp. phenotype and investigated which of the observed alterations were directly operated by FurA. Overexpression of the regulator led to changes in cellular morphology, resulting in shorter filaments with rounded cells of different sizes. The furA-overexpressing strain showed a slower photoautotrophic growth and a marked decrease in the oxygen evolution rate. Overexpression of the regulator also decreased both catalase and superoxide dismutase activities, but did not lead to an increase in the levels of intracellular reactive oxygen species. By combining phenotypic studies, reverse transcription-PCR analyses and electrophoretic mobility shift assays, we identified three novel direct targets of FurA, including genes encoding a siderophore outer membrane transporter (schT), bacterial actins (mreBCD) and the PSII reaction center protein D1 (psbA). The affinity of FurA for these novel targets was markedly affected by the absence of divalent metal ions, confirming previous evidence of a critical role for the metal co-repressor in the function of the regulator invivo. The results unravel new cellular processes modulated by FurA, supporting its role as a global transcriptional regulator in Anabaena sp. PCC 712

The Challenge of Iron Stress in Cyanobacteria

Iron is an essential nutrient for most living organisms. Due to the low solubility of ferric iron at physiological pH, the transition from an anaerobic atmosphere to the actual oxidant environment caused a dramatical decrease of iron bioavailability. Therefore, most organisms had to adapt their lifestyle to survive under an iron-depleted environment. In cyanobacteria, the electron transport chains involved in photosynthesis and respiration, as well as the enzymes involved in nitrogen metabolism have a high content of iron. Hence, cyanobacterial iron requirements are much higher than those of heterotrophic organisms. In this chapter, we revise different strategies developed by this important group of microorganisms to cope with iron deficiency, as well as the regulatory networks involved in the homeostasis of this indispensable element

Rammed earth walls in Mediterranean climate: material characterization and thermal behaviour

Rammed earth is considered a very sustainable construction system due to its low embodied energy, long service life and high recyclability. However, authors found that there is a lack of experimental results at real scale regarding rammed earth thermal behaviour. For this reason, this paper is first focused on the characterization of two different types of earth in order to check the suitability of being used in rammed earth walls. After the characterization, two experimental cubicle-shape buildings were built in Barcelona and Puigverd de Lleida (Spain) in order to test the thermal behaviour of their walls in two different climatic conditions. Temperature profiles inside walls have been monitored using thermocouples and temperature profile of southern walls was analysed in free floating conditions during summer and winter periods of 2013. Results show that thermal amplitude from outside to inside temperatures are decreased by rammed earth walls, achieving constant temperatures in inner surface of southern walls.The work was partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER)), in collaboration with the City Hall of Puigverd de Lleida. The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2014 SGR 123). This project has received funding from the European Commission Seventh Framework Programme (FP/2007-2013) under Grant agreement Nº PIRSES-GA-2013-610692 (INNOSTORAGE) and from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES). Barcelona cubicle has been conducted under the direction of the company Casa S-Low, with the collaboration of Luis Allepuz y Cristian Poza in their final degree project at EPSEB (UPC)

Addition of microencapsulated PCM into single layer mortar: physical and thermal properties and fire resistance

The energy consumption in buildings has increased in the last years due to the energy demand for thermal comfort. The improvement of thermal properties in building materials is one of the key points to achieve a reduction of the energy demand. Thermal energy storage (TES) is an alternative to save energy that has been investigated extensively in recent years. The addition of phase change materials (PCM) in a material increases its thermal inertia because PCM are able to store and release energy in sensible and latent heat. In this paper coatings used in the outer walls of buildings are studied, in particular single layer mortar. Microencapsulated paraffin PCM is added into the material to improve the thermal properties of the building envelope. The use of PCM combined with thermal insulation can reduce the energy consumption of buildings by absorbing heat gains and reducing the heat flow. Two types of single layer mortar Weber.Therm.Mineral commerzialized by Weber Saint Gobain incorporating different percentages of microencapsulated PCM type Micronal® DS5001 (20%, 10% and 0%) in their formulations are studied in this paper. The main objective of this work is to analyze the effect of PCM addition on the properties of two single layer mortars. Fresh mortar properties, as well as fire behavior, physical, mechanical and thermal properties of hardened mortar have been evaluated. The results show that physical and mechanical properties of single layer mortar are affected by the addition of microencapsulated PCM. Compressive strength decreases 60% with the addition of 20% of PCM in the formulation while the formulation with 10% of PCM has approximately the same compressive strength than a single layer mortar without PCM. The addition of PCM in the formulation decreases in 35% the adherence of the single layer mortar to a concrete surface. The presence of PCM in the mortar formulation worsens the fire behavior, due to the organic, and therefore flammable, composition of Micronal® DS5001. Flammability increases according to the percentage of PCM added. As a general conclusion, physical and mechanical properties of the single layer mortar become worse when the percentage of the added microencapsulated PCM is increased. Nevertheless, an improvement of thermal properties is expected and the quantification will be done that could justify the addition of PCM to some extent.Peer ReviewedPostprint (published version

Redox-based transcriptional regulation in prokaryotes: revisiting model mechanisms

Significance: The successful adaptation of microorganisms to ever-changing environments depends, to a great extent, on their ability to maintain redox homeostasis. To effectively maintain the redox balance, cells have developed a variety of strategies mainly coordinated by a battery of transcriptional regulators through diverse mechanisms. Recent Advances: This comprehensive review focuses on the main mechanisms used by major redox-responsive regulators in prokaryotes and their relationship with the different redox signals received by the cell. An overview of the corresponding regulons is also provided. Critical Issues: Some regulators are difficult to classify since they may contain several sensing domains and respond to more than one signal. We propose a classification of redox-sensing regulators into three major groups. The first group contains one-component or direct regulators, whose sensing and regulatory domains are in the same protein. The second group comprises the classical two-component systems involving a sensor kinase that transduces the redox signal to its DNA-binding partner. The third group encompasses a heterogeneous group of flavin-based photosensors whose mechanisms are not always fully understood and are often involved in more complex regulatory networks. Future Directions: Redox-responsive transcriptional regulation is an intricate process as identical signals may be sensed and transduced by different transcription factors, which often interplay with other DNA-binding proteins with or without regulatory activity. Although there is much information about some key regulators, many others remain to be fully characterized due to the instability of their clusters under oxygen. Understanding the mechanisms and the regulatory networks operated by these regulators is essential for the development of future applications in biotechnology and medicine