Adsorption of 4,4′-Dithiodipyridine Axially Coordinated to Iron(II) Phthalocyanine on Au(111) as a New Strategy for Oxygen Reduction Electrocatalysis

The coordination of PySSPy to FePc was monitored by UV/Vis spectroscopy while the adsobed FePc, anchored by PyS−Au(111), was examined by in situ STM in 0.1 M HClO4 and X-ray photoelectron spectroscopy (XPS). Rotating-disc-electrode (RDE) and linear-sweep-voltammetry (LSV) studies on the resulting FePc-modified Au(111) electrodes in an oxygen-saturated 0.1 M NaOH electrolyte exhibit excellent electrocatalytic properties for the oxygen reduction reaction (ORR), with a smaller overpotential than that observed for Au(111) with FePc deposited by direct adsorption from a benzene solution.Facultad de Ciencias Exacta

Effect of the electrode potential on the surface composition and crystal structure of LiMn2O4 in aqueous solutions

Cubic spinel LiMn2O4 has been studied for the reversible extraction of Li+ from natural brine after the application of suitable electrode potentials. In this work we report on the insertion/extraction of Li+ from natural brine of Olaroz salt flat (Jujuy, Argentina) and aqueous LiCl solutions into/from Li1-xMn2O4 (0 < x ≤ 1) to determine changes in the crystal structure and surface composition upon electrochemical polarization. In agreement with the behavior in organic electrolytes, we found that the insertion and extraction of Li+ proceeds via a two stage process and that the crystal structure undergoes two cubic phase transitions as the lattice is expanded or contracted. Contrary to the behavior in organic solvents, no decomposition layer is formed on the electrode surface and the surface composition can be controlled with the electrode potential. We also found that sodium cations present in natural brine are not inserted into the crystal lattice in the potential window explored, however they are adsorbed on the oxide surface blocking Li+ adsorption sites and decreasing the rate of Li+ exchange.Fil: Marchini, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Calvo, Ernesto Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Williams, Federico José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Modelo predictivo de la variación de los niveles de contaminación en función del tráfico urbano utilizando herramientas de Inteligencia Artificial

Elaboración de un modelo predictivo de los niveles de contaminación, con el fin de identificar aquellas situaciones en las que el tráfico va a provocar que se superen determinados límites de contaminantes. El modelo se creará utilizando herramientas de Inteligencia Artificial

Role of coherence in quantum-dot-based nanomachines within the Coulomb blockade regime

During the last decades, quantum dots within the Coulomb blockade regime of transport have been proposed as essential building blocks for a wide variety of nanomachines. This includes thermoelectric devices, quantum shuttles, quantum pumps, and even quantum motors. However, in this regime, the role of quantum mechanics is commonly limited to provide energy quantization while the working principle of the devices is ultimately the same as their classic counterparts. Here, we study quantum-dot-based nanomachines in the Coulomb blockade regime, but in a configuration where the coherent superpositions of the dots' states plays a crucial role. We show that the studied system can be used as the basis for different forms of "true"quantum machines that should only work in the presence of these coherent superpositions. We analyze the efficiency of these machines against different nonequilibrium sources (bias voltage, temperature gradient, and external driving) and the factors that limit it, including decoherence and the role of the different orders appearing in the adiabatic expansion of the charge/heat currents.Fil: Ribetto, Federico Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquímicas y Naturales. Departamento de Física; ArgentinaFil: Bustos Marun, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas; ArgentinaFil: Calvo, Hernan Laureano. Universidad Nacional de Rio Cuarto. Facultad de Cs.exactas Fisicoquímicas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentin

Role of coherence in quantum-dot-based nanomachines within the Coulomb blockade regime

During the last decades, quantum dots within the Coulomb blockade regime of transport have been proposed as essential building blocks for a wide variety of nanomachines. This includes thermoelectric devices, quantum shuttles, quantum pumps, and even quantum motors. However, in this regime, the role of quantum mechanics is commonly limited to provide energy quantization while the working principle of the devices is ultimately the same as their classic counterparts. Here, we study quantum-dot-based nanomachines in the Coulomb blockade regime, but in a configuration that resembles the quantum mechanics' paradigmatic experiment: the double-slit. We show that the coherent superposition of states appearing in this configuration can be used as the basis for different forms of "true" quantum machines. We analyze the efficiency of these machines against different non-equilibrium sources (bias voltage, temperature gradient, and external driving) and the factors that limit it, including decoherence and the role of the different orders appearing in the adiabatic expansion of the charge/heat currents.Comment: 16 pages, 7 figure

Changes in quality of care and costs induced by implementation of a diabetes program in a social security entity of Argentina

Purpose: To measure the impact of a diabetes and cardiovascular risk factors program implemented in a social security institution upon short- and long-term clinical/metabolic outcomes and costs of care. Methods: Observational longitudinal cohort analysis of clinical/metabolic data and resource use of 300 adult male and female program participants with diabetes before (baseline) and 1 and 3 years after implementation of the program. Data were obtained from clinical records (Qualidiab) and the administration's database. Results: The implementation of the program in "real world" conditions resulted in an immediate and sustainable improvement of the quality of care provided to people with diabetes incorporated therein. We also recorded a more appropriate oral therapy prescription for hyperglycemia and cardiovascular risk factors (CVRFs), as well as a decrease of events related to chronic complications. This improvement was associated with an increased use of diagnostic and therapeutic resources, particularly those related to pharmacy prescriptions, not specifically used for the control of hyperglycemia and other CVRFs. Conclusion: The implementation of a diabetes program in real-world conditions results in a significant short- and long-term improvement of the quality of care provided to people with diabetes and other CVRFs, but simultaneously increased the use of resources and the cost of diagnostic and therapeutic practices. Since controlled studies have shown improvement in quality of care without increasing costs, our results suggest the need to include management-control strategies in these programs for appropriate medical and administrative feedback to ensure the simultaneous improvement of clinical outcomes and optimization of the use of resources.Centro de Endocrinología Experimental y AplicadaFacultad de Ciencias MédicasFacultad de Ciencias Económica

Holistic development of a low-energy ammonia-based process for CO2 capture with solid formation

Absorption-based gas treatment processes allow removing CO2 from flue gas streams of large CO2-point sources, e.g. coal and natural gas fired power plants, cement plants, and steelworks, and make CO2 available at conditions suitable for geological storage. Therefore, it represents a key option in the portfolio of measures required to mitigate climate change and a valuable bridging technology that can support the shift towards a renewable-based supply of energy and chemicals. Among existing options, the chilled ammonia process (CAP) is a promising solution on the verge of commercialization. In the CAP, a cold ammonia solution absorbs CO2 from the flue gas in an absorption tower. The resulting CO2-rich solution releases CO2 upon moderate heating, while the (partially) regenerated ammonia solution can be recycled to the absorption section. At several points in the process flow-scheme, the liquid composition may exceed the solubility of the intermediate compounds at the relevant temperature. Solid formation can lead to clogging of process units. On the other hand, the formation of solids can increase the CO2 uptake capacity of the solvent with beneficial effects on the specific energy demand per unit of mass of CO2 captured. We have developed a so-called controlled solid formation-CAP (CSF-CAP), which successfully reduces the energy demand by exploiting solid formation. The new process controls the formation, separation, and subsequent dissolution of solids in a dedicated process section, whereas the absorption and stripping columns are kept free of solids. Our holistic process development strategy comprises (i) thermodynamics and (ii) kinetics, (iii) process synthesis, (iv) process integration, and (v) process optimization. The work on thermodynamics makes use of phase diagrams of the CO2-NH3-H2O system to map the process streams and analyze criticalities with respect to solid formation and opportunities for optimization. The analysis showed that the energetic optimization pushes the solvent composition towards the solubility limit. In the CSF-CAP, the CO2-rich solution is cooled down in a crystallizer to form solid ammonium bicarbonate (BC). The generated suspension is separated in a hydro-cyclone into (i) a rich slurry, which is sent to the regeneration unit, and (ii) a clear solution, which is sent to the top of the absorber. Due to the solid formation and separation, the latter stream can be introduced at lower temperature enabling a more effective control of the NH3 slip to the gas. The investigation of the kinetics considers both mass transfer and solid formation. On the one hand, pilot plant tests of the CO2 absorber have been carried out in order to study the reactive absorption process. On the other hand, the crystallization kinetics of BC in aqueous solution has been measured. The experimental investigation of this system is complicated by the evaporation of CO2 and NH3 from the solution as well as by the decomposition of the salts. Therefore, a temperature-controlled batch reactor, in which the volume of the vapor phase is minimized to limit the influence of the VLE on the liquid composition, has been developed. Metastable zone width data have been obtained, and BC growth kinetics has been modelled from the concentration profile during batch cooling seeded crystallization experiments with the help of a population balance model. The synthesis of the solid handling section has been developed combining mass, energy and population balances for the crystallization and dissolution into a rigorous rated-based model. Several process configurations, where mixed suspension mixed product removal (MSMPR) are coupled with scraped surface heat exchangers (SSHE) crystallizers, have been compared by optimizing the process productivity and energy needs. As a result, different optimal crystallization trajectories have been identified. Our optimization approach relies on a performance assessment based on the irreversibilities of the process as objective function. Equilibrium-based process simulations under the assumptions reported by Sutter et al. [1] led to an efficiency improvement of 17% in the CSF-CAP with respect to the conventional CAP. In our presentation, we will show our latest results on absorption kinetics, BC growth rate modelling, optimized flow scheme for the solid handling section, and optimal operating conditions of the process found for different flue gas compositions and CAP configurations. [1] D. Sutter, M. Gazzani and M. Mazzotti, Faraday Discuss., 2016, 192, 59-8

Initial Impact and Socioeconomic Compensation for the Closure of a Coal-Fired Power Plant in a Local Entity

[Abstract] This work contributes to improving the relevant information for the local participatory process, in a context of just energy transition. A proposal has been prepared for an objective estimate of the initial impact and the minimum socioeconomic compensation for the closure of a conventional coal-fired thermal power plant in the affected local entity. This has allowed (1) specifying and contextualizing the effects into which the initial impact of the closure can be divided, with the inclusion of the circular effect; (2) obtaining an indicator of the minimum compensation that would need to be set to neutralize this impact; and (3) establishing recommendations and conclusions based on the evidence obtained.This research was funded by MITECO Ministry (Government of Spain) and the As Pontes City Council.: 2019/C004/000030Concello das Pontes de García Rodríguez; 2019/C004/00003

A dynamical model for Brownian molecular motors driven by inelastic electron tunneling

In recent years, several artificial molecular motors driven and controlled by electric currents have been proposed. Similar to Brownian machines, these systems work by turning random inelastic tunneling events into a directional rotation of the molecule. Despite their importance as the ultimate component of future molecular machines, their modeling has not been sufficiently studied. Here, we develop a dynamical model to describe these systems. We illustrate the validity and usefulness of our model by applying it to a well-known molecular motor, showing that the obtained results are consistent with the available experimental data. Moreover, we demonstrate how to use our model to extract some difficult-to-access microscopic parameters. Finally, we include an analysis of the expected effects of current-induced forces (CIFs). Our analysis suggests that, although nonconservative contributions of the CIFs can be important in some scenarios, they do not seem important in the analyzed case. Despite this, the conservative contributions of CIFs could be strong enough to significantly alter the system's dynamics