Homogeneously bright, flexible and foldable lighting devices with functionalised graphene electrodes

Alternating current electroluminescent technology allows the fabrication of large area, flat and flexible lights. Presently the maximum size of a continuous panel is limited by the high resistivity of available transparent electrode materials causing a visible gradient of brightness. Here, we demonstrate that the use of the best known transparent conductor FeCl$_{3}$-intercalated few-layer graphene boosts the brightness of electroluminescent devices by 49$\%$ compared to pristine graphene. Intensity gradients observed for high aspect ratio devices are undetectable when using these highly conductive electrodes. Flat lights on polymer substrates are found to be resilient to repeated and flexural strains.Comment: Published on ACS Materials and Interface

Trust and accountability in times of pandemics

La pandemia de COVID-19 llegó en un contexto de creciente polarización política y desconfianza en las instituciones políticas en muchos países. ¿Pudieron las deficiencias en la gestión de la pandemia erosionar la confianza en las instituciones públicas? ¿Interfirió la ideología de los ciudadanos en la forma en que procesaban la información sobre el desempeño de los Gobiernos? Para investigar ambas cuestiones, en noviembre de 2020 llevamos a cabo en España un experimento online prerregistrado. A los encuestados del grupo de tratamiento les proporcionamos información sobre el número de rastreadores de contactos en su comunidad autónoma, una política clave bajo el control de los Gobiernos autonómicos. Encontramos que las personas sobrestiman en gran medida el número de rastreadores de su región. Cuando proporcionamos el número real de rastreadores, encontramos lo siguiente: una pérdida de la confianza en los Gobiernos; una reducción en la voluntad de financiar instituciones públicas, y una disminución de la aceptación de la vacuna contra el COVID-19. También encontramos que los individuos cambian endógenamente su atribución de responsabilidades al recibir el tratamiento. En las regiones donde los Gobiernos regionales y central están gobernados por diferentes partidos, los simpatizantes del Gobierno regional reaccionan a las malas noticias sobre la gestión del Gobierno atribuyendo una mayor responsabilidad al Gobierno central. A esto lo llamamos «efecto de blame-shifting». En estas regiones, la información negativa no se traduce en una menor intención de voto para el Gobierno regional. Estos resultados sugieren que la rendición de cuentas puede ser particularmente difícil en entornos con alta polarización política y donde las áreas de responsabilidad no están claramente delimitadas.The COVID-19 pandemic took place against the backdrop of growing political polarization and distrust in political institutions in many countries. Did deficiencies in government performance further erode trust in public institutions? Did citizens’ ideology interfere with the way they processed information on government performance? To investigate these two questions, we conducted a pre-registered online experiment in Spain in November 2020. Respondents in the treatment group were provided information on the number of contact tracers in their region, a key policy variable under the control of regional governments. We find that individuals greatly over-estimate the number of contact tracers in their region. When we provide the actual number of contact tracers, we find a decline in trust in governments, a reduction in willingness to fund public institutions and a decrease in COVID-19 vaccine acceptance. We also find that individuals endogenously change their attribution of responsibilities when receiving the treatment. In regions where the regional and central governments are controlled by different parties, sympathizers of the regional incumbent react to the negative news on performance by attributing greater responsibility for it to the central government. We call this the blame shifting effect. In those regions, the negative information does not translate into lower voting intentions for the regional incumbent government. These results suggest that the exercise of political accountability may be particularly difficult in settings with high political polarization and areas of responsibility that are not clearly delineated

Wrapped M2/M5 Duality

A microscopic accounting of the entropy of a generic 5D supersymmetric rotating black hole, arising from wrapped M2-branes in Calabi-Yau compactified M-theory, is an outstanding unsolved problem. In this paper we consider an expansion around the zero-entropy, zero-temperature, maximally rotating ground state for which the angular momentum J_L and graviphoton charge Q are related by J_L^2=Q^3. At J_L=0 the near horizon geometry is AdS_2 x S^3. As J_L^2 goes to Q^3 it becomes a singular quotient of AdS_3 x S^2: more precisely, a quotient of the near horizon geometry of an M5 wrapped on a 4-cycle whose self-intersection is the 2-cycle associated to the wrapped-M2 black hole. The singularity of the AdS_3 quotient is identified as the usual one associated to the zero-temperature limit, suggesting that the (0,4) wrapped-M5 CFT is dual near maximality to the wrapped-M2 black hole. As evidence for this, the microscopic (0,4) CFT entropy and the macroscopic rotating black hole entropy are found to agree to leading order away from maximality.Comment: 10 pages, no figure

Metastability effects on the photoluminescence of ZnO nano-micro structures grown at low temperature and influence of the precursors on their morphology and structure

Nanocrystalline ZnO films were grown on silicon substrate by hydrothermal synthesis at 125 °C, using diethanolamine as stabilizer. A powder containing ZnO spheres, with diameters between 100 to 200 nm and formed by aggregation of ZnO nanoparticles, was also obtained as a secondary reaction product. The samples were studied by scanning electron microscopy, X-ray diffraction and photoluminescence (PL) spectroscopy. The effects of the [diethanolamine]/[Zn+2] molar ratio on morphological, structural and optical properties were studied, as well as the effect of laser illumination (=325 nm) and annealing treatment on photoluminescence properties. The film samples exhibited a compact columnar structure, with thickness between 180 to 210 nm, which were not strongly affected by the diethanolamine concentration. The X-ray diffraction patterns from the films evidenced preferred orientation along the c-axis of the ZnO wurzite structure; while the nanospheres did not show any preferential crystalline direction. The PL spectra from the films showed large initial UV emission and a weak defect band centered in the yellow. A PL evolution while the samples were UV illuminated, attributed to oxygen vacancy generation following the photoinduced equilibration of metastable structures, was observed.Fil: Gonzalez, Vanessa. Instituto de Física del Noroeste Argentino, INFINOA (CONICET-UNT); Argentina. NanoProject - LNPD, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán; ArgentinaFil: Marín Ramírez, Oscar Alonso. Instituto de Física del Noroeste Argentino, INFINOA (CONICET-UNT); Argentina. NanoProject - LAFISO, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán; ArgentinaFil: Tirado, Monica Cecilia. Instituto de Física del Noroeste Argentino, INFINOA (CONICET-UNT); Argentina. NanoProject - LNPD, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán; ArgentinaFil: Comedi, David Mario. NanoProject - LAFISO, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán; Argentina. Instituto de Física del Noroeste Argentino, INFINOA (CONICET-UNT); Argentin

Effects of methanol on morphology and photoluminescence in solvothermal grown ZnO powders and ZnO on Si

ZnO nano and microstructures were obtained by solvothermal synthesis using hexamethylenetetramine (HMTA) as alkaline agent, and water, water/methanol and methanol as solvents. Two types of samples were obtained: a ZnO powder that grew at the bulk solution and ZnO on silicon substrates. The effect of the solvent on the morphology and optical emission was studied, as well as the influence of the growth zone. With increasing methanol content, the morphology changed from nanorods to nanoparticles powders, and from oriented arrangement of nanorods to thin film on silicon substrates. Important changes in photoluminescence induced by the methanol content and depending on the growth zone were also observed.Fil: Marín Ramírez, Oscar Alonso. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; Argentina. Universidad Nacional de Tucumán; ArgentinaFil: González, Vanessa. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; Argentina. Universidad Nacional de Tucumán; ArgentinaFil: Tirado, Monica Cecilia. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; Argentina. Universidad Nacional de Tucumán; ArgentinaFil: Comedi, David Mario. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; Argentina. Universidad Nacional de Tucumán; Argentin

Teenagers and Automated Vehicles: Are They Ready to Use Them?

ABSTRACT: Mobility needs, expectations, and concerns vary across age groups and are closely linked to users' views on the future of the road transport system. Automated vehicles are expected to have a significant impact on the future of the road transport system, and pilot deployments are increasingly being tested in Europe and beyond, which is also thanks to the evolving regulatory landscape. As a result, several studies have started to analyse citizens' attitudes towards this technology. However, very few studies have focused on teenagers' views on automated vehicles, although today's children and teenagers could be among the first users of such vehicles. Studying teenagers and the way they envisage automated vehicles in the future is of particular significance in defining transport planning strategies and supporting upcoming policy orientations. To cover this gap, the present study aims to explore teenagers' views about automated vehicles and whether and how they could fit into their future transport setting. A series of on-line and face-to-face focus groups, a demonstration of an automated vehicle prototype, supporting engagement activities, and a post-pre survey were used to collect their views on the topic. The results show that even though the teenagers acknowledged the potential advantages, they also expressed concerns in relation to the interactions with other road users, to automated driving systems' reliability, to safety, and to data privacy. In particular, these safety concerns revealed an unwillingness on the part of the teenagers to be among the first users of automated vehicles.This research has been funded by the European Commission Joint Research Centre Institutional Funds

ZnO Nanostructures Synthesized by Vapor Transport and Liquid Phase Synthesis Techniques: Growth and Properties

In this review, we briefly describe work devoted in recent years towards the effective control of morphology, structure and optical properties of ZnO nanostructures, with particular focus on cost effective and simple methods for ZnO nanowires (NWs) fabrication. For the vapor transport technique, we describe in detail mechanisms for growth precursors generation, their transport in inert and forming gas, as well as their reactions on different pretreated substrates and corresponding growth mechanisms. As for low temperature synthesis methods, three techniques are outlined: sol-gel, solvothermal and electrophoretic deposition, with emphasis on effective morphology, structure and optical properties control. In this context, we discuss recent attempts to understand the role of solvent and alkaline agents used during solvothermal synthesis of ZnO nanostructures on their morphology and photoluminescence properties. Recent success of electrophoretic deposition of ZnO nanoparticles on pre-patterned silicon substrates in the form of NWs and NW bunches is highlighted over many previous attempts to fabricate ZnO NWs with inconvenient sacrificial templates. Finally, we present a critical discussion on the current understanding of passivation mechanisms of ZnO NW surfaces by MgO shells.Fil: Marín Ramírez, Oscar Alonso. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; ArgentinaFil: Real, Silvina Claudia. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; ArgentinaFil: Vega, Nadia Celeste. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; ArgentinaFil: Tirado, Monica Cecilia. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; ArgentinaFil: Comedi, David Mario. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; Argentin

On the properties of NiO powders obtained by different wet chemical methods and calcination

NiO powders were synthesized using coprecipitation, sol-gel, and hydrothermal synthesis methods. The powders were subjected to calcination in atmospheric air, followed by recalcination in an O2-rich atmosphere at 800°C for 2 h each. Characterization techniques, such as scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and microRaman spectroscopy, were utilized. The coprecipitation and hydrothermal methods resulted in disaggregated submicrometric particles. The average size of particles obtained by the coprecipitation method after calcination in atmospheric air and recalcination in an O2-rich atmosphere was 360 ± 140 nm and 400 ± 130 nm, respectively. Regarding the particles obtained by the hydrothermal method, the average size was 190 ± 50 and 220 ± 80 nm for calcined in atmospheric air and recalcined in O2-rich atmosphere, respectively. Conversely, the sol-gel method produced particle aggregates with an average size of 430 ± 150 nm after calcination in atmospheric air and 500 ± 200 nm for calcination in an O2-rich atmosphere. X-ray diffraction analysis revealed that only the hydrothermal method yielded pure NiO without additional Ni-related phases, irrespective of the calcination procedure. In contrast, the coprecipitation sample exhibited a Ni2O3 phase after calcination in atmospheric air, which disappeared after recalcination in an O2-rich atmosphere. The sol-gel-derived sample maintained a Ni phase after both calcination processes. Analysis of the crystallite size demonstrated an increase after recalcination in an O2-rich atmosphere for the hydrothermal and sol-gel-derived samples, while a decrease was observed for the coprecipitation-derived sample. Raman spectra exhibited defect-enabled first-order forbidden phonon modes that were sensitive to the synthesis route. The two magnon phonon modes also demonstrated dependency on the route, indicating variations in defect structures. Photocatalytic evaluation using methylene blue degradation in aqueous solutions indicated better performance for the powders recalcined in an O2-rich atmosphere.Fil: Alastuey, Patricio. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; ArgentinaFil: Pais Ospina, Daniel Humberto. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; ArgentinaFil: Comedi, David Mario. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; ArgentinaFil: Tirado, Monica Cecilia. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; ArgentinaFil: Marín Ramírez, Oscar Alonso. Universidad Nacional de Tucumán. Instituto de Física del Noroeste Argentino. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Física del Noroeste Argentino; Argentin