Derivados de quinonas como sistemas electroactivos para su aplicación en baterías de flujo redox

The intermittent and fluctuating nature of renewable energy sources such as wind and solar energy, highlights the need of the development of energy storage devices capable of modulating the demand of energy in favor of increasing their application. On the other hand, Redox Flow Batteries (RFB) represent the most suitable electrochemical devices for large-scale energy storage applications due to their modular design, scalability and flexible operation. However, most of the RFBs currently available are based on the use of metallic species as active electrolytes, which are quite expensive, not very abundant and their extraction or obtaining entails problems associated with environmental impact. From this, organic redox materials based on quinones rise as alternative and promising candidates to face these drawbacks due to the important advantages that the use of these species entails, such as molecular diversity, structural adaptability and natural abundance. Due to the structural diversity of organic molecules, the discovery of quinones or other redox active organic molecules for energy storage applications is an open field of research. In this research project, we present a high-performance computational approach that applied a total of 132 molecules between quinones and hydroquinones, corresponding to 66 redox pairs, which were used both for the development of a calibration model, as well as for the molecular screening. Based on this, a highly precise method was established for the calculation of EºTeó in aqueous solvent based on ab initio / DFT theoretical calculations with the use of the functional hybrid B3LYP 6-311 ++ G (d, p). The linear fit achieved in the calibration method (R2 = 0.997) and the low mean square error observed (0.0142 V) suggest a high level of precision in terms of calculating EºTeó even higher than many reported computational studies. From the molecular screening, 8 species derived from 1,4-BQ were identified that present an EºTeó value suitable for its application as negative redox electrolytes or as positive redox electrolytes in RFB and, with a minimum value of ∆GºSolv (-81 k·J/mol). Within these species, four species were candidates for use as a negative electrolyte (43, 47, 52 and 53) and four species as a positive electrolyte (31, 32, 41 and 50). From these results, it is possible to propose the chemical synthesis of an aqueous quinone redox system from theoretical calculations for its application in redox flow batteries with a cell potential of ≈ 0.65 V and with good solubility in aqueous medium. In addition, from the studies performed by cyclic voltammetry and the calculated electrochemical parameters, 3,5-diamino-1,2,4-triazole was identified as an organic species with interesting electrochemical properties for its application in redox flow batteries in alkaline medium, and of XVI which no evidence is found until the moment of its study as a possible redox electrolyte for energy storage applications in flow batteriesLa naturaleza intermitente y fluctuante de las fuentes de energía renovables como la energía eólica y solar, resaltan como una necesidad apremiante el desarrollo de dispositivos de almacenamiento de energía capaces de modular los picos de generación y demanda de energía a favor de integrar en mayor medida la aplicación de las energías renovables. Por su parte, las Baterías de Flujo Redox (BFR) representan los dispositivos electroquímicos más adecuados para aplicaciones de almacenamiento de energía a gran escala debido a su diseño modular, escalabilidad y operación flexible. Sin embargo, la mayoría de las BFR disponibles actualmente se basan en la utilización de especies metálicas como electrolitos activos, los cuales son bastante costosos, poco abundantes y su extracción u obtención conllevan problemas asociados con la contaminación ambiental. A partir de ello, los materiales orgánicos redox basados en quinonas se alzan como candidatos alternativos y prometedores para hacer frente a estos inconvenientes debido a las importantes ventajas que conlleva el uso de estas especies como lo son la diversidad molecular, la adaptabilidad estructural y la abundancia natural. Debido al diversidad estructural de las moléculas orgánicas, el descubrimiento de quinonas u otras moléculas orgánicas activas redox para aplicaciones de almacenamiento de energía es un campo abierto de investigación. En el presente proyecto de investigación, presentamos un enfoque computacional de alto rendimiento que aplicamos a un total de 132 moléculas entre quinonas e hidroquinonas, correspondientes a 66 pares redox, las cuales se emplearon tanto para el desarrollo de un modelo de calibración, así como para el cribado molecular. A partir de ello se estableció un método altamente preciso para el cálculo del EºTeó en solvente acuoso basado en cálculos teóricos ab initio/DFT con el empleo del funcional híbrido B3LYP 6-311++G(d,p). El ajuste lineal alcanzado en el método de calibración (R2 =0.997) y el bajo error cuadrático medio observado (0.0142 V) sugieren un gran nivel de precisión en cuanto al cálculo de EºTeó incluso superior a muchos estudios computacionales reportados. Del cribado molecular se identificaron 8 especies derivadas de la 1,4- BQ que cumplieron con un valor de EºTeó adecuado para su aplicación como electrolitos redox negativos o como electrolitos redox positivos en una BFR y, con un valor mínimo de ∆GºSolv (-81 k·J/mol). Dentro de estas especies, cuatro especies resultaron candidatas para su uso como electrolito negativo (43, 47, 52 y 53) y cuatro especies como electrolito positivo (31, 32, 41 y 50). De estos resultados, es posible proponer la síntesis química de un sistema redox acuoso de quinonas a partir de cálculos teóricos para su aplicación en baterías de flujo redox con un potencial de celda de ≈ 0.65 V y con buena solubilidad en medio acuoso. XIV Además, a partir de los estudios realizados por voltamperometría cíclica y de los parámetros electroquímicos calculados, se identificó al 3,5-diamino-1,2,4-triazol como una especie orgánica con propiedades electroquímicas interesantes para su aplicación en baterías de flujo redox en medio alcalino, y de la cual no se encuentra evidencia hasta el momento de su estudio como posible electrólito redox para aplicaciones de almacenamiento de energía en baterías de flujo

Strain and temperature measurement discrimination with forward Brillouin scattering in optical fibers

A novel method that enables simultaneous and discriminative measurement of strain and temperature using one single optical fiber is presented. The method is based on the properties of transverse acoustic mode resonances (TAMRs) of the optical fiber. In particular, it is based on the different sensitivity to temperature and strain that exhibit the radial modes R(0,m) and a family of torsional-radial modes denoted as TR(1)(2,m). We show that the resonance frequencies of both types of resonances shift linearly with temperature and strain, but at different rates. By the combined use of the different sensitivities of the two families of TAMRs, we experimentally demonstrate discriminative measurements of strain and temperature. A detection limit of strain and temperature better than 25 με and 0.2 °C is achieved

High accuracy measurement of Poisson's ratio of optical fibers and its temperature dependence using forward-stimulated Brillouin scattering

Transverse acoustic mode resonances enable a high accuracy determination of Poisson's ratio and elastic properties of optical fibers. An all-optical pump and probe technique is used for efficient excitation and accurate characterization of both, radial and torsional-radial acoustic resonances of optical fibers. Simple and precise algebraic expressions for the frequencies of high order acoustic resonances are derived, enabling a rigorous analysis of the experimental data using standard least squares fitting. Following this approach, the determination of Poisson's ratio does not require the measurement of any physical length, but only frequency measurements are required. An accuracy better than 1 is achieved. The dependence of the fiber Poisson's ratio with temperature is also determined experimentally

Recent advances in Forward Brillouin Scattering: Sensor applications

In-fiber opto-mechanics based on forward Brillouin scattering has received increasing attention because it enables sensing the surrounding of the optical fiber. Optical fiber transverse acoustic resonances are sensitive to both the inner properties of the optical fiber and the external medium. A particularly efficient pump and probe technique¿assisted by a fiber grating¿can be exploited for the development of point sensors of only a few centimeters in length. When measuring the acoustic resonances, this technique provides the narrowest reported linewidths and a signal-tonoise ratio better than 40 dB. The longitudinal and transverse acoustic velocities¿normalized with the fiber radius¿can be determined with a relative error lower than 10−4, exploiting the derivation of accurate asymptotic expressions for the resonant frequencies. Using this technique, the Poisson's ratio of an optical fiber and its temperature dependence have been measured, reducing the relative error by a factor of 100 with respect to previously reported values. Using a single-point sensor, discriminative measurements of strain and temperature can be performed, achieving detection limits of ±25 με and ±0.2 °C. These results show the potential of this approach for the development of point sensors, which can be easily wavelength-multiplexed

Flora de interés corológico para Andalucía occidental

Flora of chorologycal interest for Western AndalusiaPalabras clave. Corología, Biogeografía, Andalucía Occidental, España.Key words. Chorology, Biogeography, Western Andalusia, Spain

Effects of nitrate contamination and seasonal variation on the denitrification and greenhouse gas production in La Rocina stream (Doñana National Park, SW Spain)

Climatic influence (global warming and decreased rainfall) could lead to an increase in the ecological and toxicological effects of the pollution in aquatic ecosystems, especially contamination from agricultural nitrate (NO3 −) fertilizers. Physicochemical properties of the surface waters and sediments of four selected sites varying in NO3 − concentration along La Rocina Stream, which feeds Marisma del Rocio in Do˜nana National Park (South West, Spain), were studied. Electrical conductivity, pH, content in macro and microelements, total organic carbon and nitrogen, and dissolved carbon and nitrogen were affected by each sampling site and sampling time. Contaminant NO3 − in surface water at the site with the highest NO3 − concentration (ranged in 61.6–106.6mgL−1) was of inorganic origin, most probably from chemical fertilizers, as determined chemically (90% of the total dissolved nitrogen from NO3 −) and by isotopic analysis of ı15N-NO3 −. Changes in seasonal weather conditions and hydrological effects at the sampling sites were also responsible for variations in some biological activities (dehydrogenase, -glucosidase, arylsulphatase, acid phosphatase and urease) in sediments, as well as in the production of the greenhouse gases CO2, CH4 and N2O. Both organic matter and NO3 − contents influenced rates of gas production. Increased NO3 − concentration also resulted in enhanced levels of potential denitrification measured as N2O production. The denitrification process was affected by NO3 − contamination and the rainfall regimen, increasing the greenhouse gases emissions (CO2, CH4 and especially N2O) during the driest season in all sampling sites studied.This work was supported by grants CGL2006-06870 and CTM2009-1473-C02-02 from Ministerio de Ciencia e Innovación (Spain) and RNM-4746 from Consejería de Innovación, Ciencia y Empresa de la Junta de Andalucía (Spain), all of them co-financed by the European Regional Development Fund (ERDF). Support of Junta de Andalucía to Research Group BIO-275 is also acknowledged. D. David Correa thanks Ministerio de Educación for predoctoral grant AP2007-03967.Peer reviewe

The germplasm bank of the Botanical Garden of the University of Malaga.

The collection of the Germplasm Bank of the University of Malaga began recently associated with its Botanical Garden, in October 2021. The collection is made up of diaspores (fruits/seeds) of plant species belonging to the botanical garden itself and other native species of the vegetation of different areas of the province of Malaga. After the identification of the plants and the collection of the samples, standardized procedures are applied for their adequate conservation in the short and medium term in refrigerators at 4ºC, since the objective is to maintain a dynamic collection. Additionally, the database allows international exchanges and research activities such as viability studies or the elaboration of a photo atlas supported by morphometric studies of the preserved structures. The biodiversity conserved in this germplasm bank will be also very useful in a scenario of global change in which many species are being threatened, or even disappearing, since it constitutes a reservoir that guarantees the possible recovery of the different species whose diasporas have been preserved. Currently, the germplasm bank contains a total of 155 samples belonging to 115 taxa subject to strict protocols that guarantees the maintenance of their viability and genetic integrity, the sanitary conditions of the germplasm, its availability and the physical security of the collections.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Novedades corológicas para la flora de la provincia de Córdoba

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Modelo cinético para la simulación de la autoignición en un proceso de combustión homogénea de encendido por compresión (HCCI)

El conocimiento del punto de autoignición de los motores bajo combustión HCCI es un apartado fundamental en el futuro desarrollo de estos motores. En este trabajo tratamos de proporcionar una herramienta computacional, con un detallado estudio de la cinética química, la cual resulta imprescindible para la compresión del fenómeno HCCIThis paper reviews some of the engine research results and available data from HCCI combustion kinetics studies. Homogeneous Charge Compression Ignition (HCCI) combustion has recently emerged as a viable alternative combustion process to the conventional spark ignition or compression ignition process for internal combustion engines, owing too its potential for high efficiency and extremely low NOx and particulate emissions. Methods for automatic quasi-steady-state reduction of reaction mechanisms a life time measure to detect equilibrated species has been developed and applied to homogeneous model of HCCI engine fuelled with its two fuels

Miniaturized high gain flexible spiral antenna tested in human-like tissue

A miniaturized helical antenna is presented in this work. The antenna is flexible, it is 6100 μm long and it has a diameter of 352 μm. This antenna has such a small cross-section, that permits to be implanted in the human body with fine syringes and minimally invasive surgeries. The antenna can be used to receive power and/or send information in medical devices. The antenna is made of biocompatible materials: polytetrafluoroethylene (PFTE) and copper. The fundamental parameters of the antenna have been simulated and experimentally measured in animal human-like tissues, showing good agreement. The resonant frequency of the antenna is 4.7 GHz, with a reflection coefficient of −25.1 dB, and a gain of −4.7 dBi. As expected, the resonant frequency decreases inside biological tissues comparing to the free-space open-air measurement. Reducing the resonant frequency is an advantage because power signals can penetrate deeper into body tissues