Unitized regenerative polymeric fuel cell modeling

The research's objective is to have a single machine to function as fuel cell and electrolyser based and needs, that is to say, unitized regenerative fuel cell (when fed to the machine with electric power and water flows will be obtained and H2 and O2 and conversely when the machine is fuelled with H2 and O2 will get water, heat and electricity) The study focuses on polymeric fuel cells and polymeric electrolysers. The development of this machine will make a very significant cost reduction (currently to use hydrogen as an energy store needed the electrolyser and fuel cell) as a single machine may replace the fuel cell and electrolyser. The achievement of the objective mentioned above, have been going by completing a series of stages. The stages addressed in this work are: ¿ A first stage, which will be studied in detail the polymeric fuel cells and polymeric electrolysers, in order to see the similarities between the machines and to design the unitized regenerative fuel cell. ¿ A second stage of simulation, which will develop models to show the behaviour of the unitized regenerative fuel cell and compare results with those obtained from the theoretical. ¿ A third stage of model verification generated polymer fuel cells and electrolyzers polymer on the market

Fe(II) spin crossover complexes of a derivative of 2,6-bis(pyrazol-1-yl)pyridine (1-bpp) functionalized with a carboxylic acid in the 3-pyridyl position

The preparation of a new bis(pyrazol-1-yl)pyridine (1-bpp) derivative functionalized with a carboxylic acid in the 3-pyridyl position, bpp3-COOH ligand is reported together with the structure and spin-crossover (SCO) properties of [FeII(bpp3-COOH)2](ClO4)2·0.5EtOH·0.5H2O (1). Magnetic properties of 1 indicate that LS is favored. Desolvation leads to a gradual and incomplete SCO. Solvated and desolvated compounds show LIESST effect

Assessment of Hydrogen as suistinable clean energy

The progressive depletion of fossil fuels and their high contribution to the energy supply in this modern society forces that will be soon replaced by renewable fuels. But the dispersion and alternation of renewable energy production also undertake to reduce their costs to use as energy storage and hydrogen carrier. It is necessary to develop technologies for hydrogen production from all renewable energy storage technologies and the development of energy production from hydrogen fuel cells and cogeneration and tri generation systems. In order to propel this technological development discussed where the hydrogen plays a key role as energy storage and renewable energy, the National Centre of Hydrogen and Fuel Cell Technology Experimentation in Spain equipped with installations that enable scientific and technological design, develop, verify, certify, approve, test, measure and, more importantly, the facility ensures continuous operation for 24 hours a day, 365 days year. At the same time, the system is scalable so as to allow continuous adaptation of new technologies are developed and incorporated into the assembly to verify integration at the same time it checks the validity of their development. The transformation sector can be said to be the heart of the system, because without neglecting the other sectors, this should prove the validity of hydrogen as a carrier - energy storage are important efforts that have to do to demonstrate the suitability of fuel cells or internal combustion systems to realize the energy stored in hydrogen at prices competitive with conventional systems. The multiple roles to meet the fuel cells under different conditions of operation require to cover their operating conditions, many different sizes and applications. The fourth area focuses on integration is an essential complement within the installation. We must integrate not only the electricity produced, but also hydrogen is used and the heat generated in the process of using hydrogen energy. The energy management in its three forms: hydrogen chemical, electrical and thermal integration requires complicated and require a logic and artificial intelligence extremes to ensure maximum energy efficiency at the same time optimum utilization is achieved. Verification of the development and approval in the entire production system and, ultimately, as a demonstrator set to facilitate the simultaneous evolution of production technology, storage and distribution of hydrogen fuel cells has been assessed

Hybrid Quantum-Classical Monte-Carlo Study of a Molecule-Based Magnet

Using a Monte Carlo (MC) method, we study an effective model for the Fe(II)Fe(III) bimetallic oxalates. Within a hybrid quantum-classical MC algorithm, the Heisenberg S=2 and $S'=5/2$ spins on the Fe(II) and Fe(III) sites are updated using a quantum MC loop while the Ising-like orbital angular momenta on the Fe(II) sites are updated using a single-spin classical MC flip. The effective field acting on the orbital angular momenta depends on the quantum state of the system. We find that the mean-field phase diagram for the model is surprisingly robust with respect to fluctuations. In particular, the region displaying two compensation points shifts and shrinks but remains finite.Comment: 8 pages, 7 figure

Spin-crossover iron (II) complex showing thermal hysteresis around room temperature with symmetry breaking and an unusually high T(LIESST) of 120 K

We report a Fe(II) complex based on 4′,4′′ carboxylic acid disubstituted dipyrazolylpyridine that shows a spin-crossover close to room temperature associated to a crystallographic phase transition and the LIESST effect with a high T(LIESST) of 120 K

Spin-crossover compounds based on iron(II) complexes of 2,6-bis(pyrazol-1-yl)pyridine (bpp) functionalized with carboxylic acid and ethyl carboxylic acid

Four new salts of the iron(II) complex of the 2,6-bis( pyrazol-1-yl)pyridine ligand functionalized with a carboxylic acid group (bppCOOH) of formulas [Fe(bppCOOH)2](BF4)2 (1(BF4)2), [Fe(bppCOOH)2] (CF3SO3)2·yMe2CO (1(CF3SO3)2·yMe2CO), [Fe(bppCOOH)2](AsF6)2·yMe2CO (1(AsF6)2·yMe2CO) and [Fe (bppCOOH)2](SbF6)2·yMe2CO (1(SbF6)2·yMe2CO) have been prepared and characterized together with a more complete structural and photomagnetic characterization of the previously reported [Fe (bppCOOH)2](ClO4)2 (1(ClO4)2). Furthermore, the iron(II) complex of the ethyl ester derivative of bppCOOH (bppCOOEt) has been prepared and characterized (compound [Fe(bppCOOEt)2] (ClO4)2·yMe2CO, 2(ClO4)2·yMe2CO). Isostructural 1(BF4)2 and 1(ClO4)2 show an abrupt and reversible spin transition with a much lower T1/2 for the BF4− salt. CF3SO3 , SbF6 and AsF6 counteranions and the bppCOOEt ligand lead to the incorporation of solvent molecules in the structures, which play an important role in the spin-crossover properties of these compounds. In the case of 1(CF3SO3)2·yMe2CO, a spin transition is obtained after desolvation. All these compounds show a LIESST effect

Ground-State Spin Blockade in a Single-Molecule Junction

It is known that the quantum mechanical ground state of a nanoscale junction has a significant impact on its electrical transport properties. This becomes particularly important in transistors consisting of a single molecule. Because of strong electron-electron interactions and the possibility of accessing ground states with high spins, these systems are eligible hosts of a current-blockade phenomenon called a ground-state spin blockade. This effect arises from the inability of a charge carrier to account for the spin difference required to enter the junction, as that process would violate the spin selection rules. Here, we present a direct experimental demonstration of a ground-state spin blockade in a high-spin single-molecule transistor. The measured transport characteristics of this device exhibit a complete suppression of resonant transport due to a ground-state spin difference of 3/2 between subsequent charge states. Strikingly, the blockade can be reversibly lifted by driving the system through a magnetic ground-state transition in one charge state, using the tunability offered by both magnetic and electric fields

Heteroleptic Iron(II) Spin-Crossover Complexes Based on a 2,6-Bis(pyrazol-1-yl)pyridine-type Ligand Functionalized with a Carboxylic Acid

Two new heteroleptic complexes [Fe- (1bppCOOH)(3bpp-bph)](ClO4)2·solv (1·solv, solv = various solvents; 1bppCOOH = 2,6-bis(1H-pyrazol-1-yl)- isonicotinic acid; 3bpp-bph = 2,6-bis(5-([1,1′-biphenyl]-4- yl)-1H-pyrazol-3-yl)pyridine) and [Fe(1bppCOOH)- (1bppCOOEt)](ClO4)2 ·0.5Me2CO (2·0.5Me2CO, 1bppCOOEt = ethyl 2,6-bis(1H-pyrazol-1-yl)isonicotinate) were designed and prepared. The heteroleptic compound 1· solv was obtained by the combination of stoichiometric amounts of Fe(ClO4)2, 1bppCOOH, and 3bpp-bph, and it was designed to fine-tune the spin crossover (SCO) properties with respect to the previously reported homoleptic compound [Fe(1bppCOOH)2](ClO4)2. Indeed, the introduction of a new substituted 3bpp ligand induces a weaker ligand field in addition to promoting the formation of π···π and C−H···π intermolecular interactions through the biphenyl groups. For the desolvated counterpart 1, this results in a shift of the SCO curve toward room temperature and the observation of a 13 K hysteresis width. Besides, compound 2·0.5Me2CO, which represents the first example of a heteroleptic complex containing two 1bpp tridentate ligands, stabilizes the LS state at room temperature confirming the same trend observed for the corresponding homoleptic compounds. Interestingly, both 1 and 2·0.5Me2CO heteroleptic complexes exhibit photoswitchable properties when irradiating with a 523 nm laser at 10 K. Preliminary characterization of the deposited complexes on native SiO2 by X-ray absorption measurements suggests oxidation and decomposition of the complexes

Patrones de abundancia de la macrofauna asociada a macroalgas marinas a largo de la Península Ibérica

macroalgae were studied on a spatial scale along the Iberian Peninsula. Nineteen stations and four dominant algae were selected (intertidal zone: Corallina elongata and Asparagopsis armata; subtidal zone: Stypocaulon scoparium and Cladostephus spongiosus). Five environmental factors were also considered (seawater temperature, conductivity, dissolved oxygen, turbidity and pH). The Atlantic coast was characterized by lower temperature and conductivity as well as higher values of oxygen and turbidity than the Mediterranean coast. A total of 106274 macrofaunal specimens were sorted and examined (68% arthropods, 27% molluscs, 4% annelids and 1% echinoderms). Crustaceans were the dominant group in all the macroalgae (ca. 80% in C. elongata and A. armata, ca. 50% in S. scoparium and C. spongiosus) followed by molluscs, which were more abundant in the subtidal algae (ca. 40%) than in intertidal ones (ca.10%). Abundance patterns of macrofauna along the Iberian Peninsula were similar in the four studied algae. Most of crustaceans belonged to the order Amphipoda, which showed high densities (>1000 ind/1000 ml algae) along the whole Peninsula; isopods showed the highest abundances in the Atlantic, while tanaids, cumaceans and decapods were more abundant in the Mediterranean. Among molluscs, gasteropods showed highest abundances along the Atlantic coasts, whereas bivalves showed higher densities along the MediterraneanSe llevó a cabo un estudio espacial de los patrones de abundancia y distribución de la macrofauna asociada a macroalgas a lo largo de la Península Ibérica. Se seleccionaron 19 estaciones y 4 algas dominantes (zona intermareal: Corallina elongata y Asparagopsis armata; zona submareal: Stypocaulon scoparium y Cladostephus spongiosus). Se consideraron también cinco variables ambientales (temperatura del agua, conductividad, oxígeno disuelto, turbidez y pH). La costa atlántica se caracterizó por valores más bajos de temperatura y conductividad, y más altos de oxígeno y turbidez. Se examinaron 106274 individuos de la macrofauna (68% artrópodos, 27% moluscos, 4% anélidos y 1% equinodermos). Los crustáceos fueron dominantes en todas las macroalgas (alrededor del 80% en C. elongata y A. armata, y en torno al 50% en S. scoparium y C. spongiosus), seguidos por los moluscos, que fueron más abundantes en el submareal (40%) que en el intermareal (10%). Los patrones de abundancia de la macrofauna a lo largo de la Península Ibérica fueron similares en las cuatro algas estudiadas. La mayoría de los crustáceos pertenecieron al orden Amphipoda, que mostró densidades muy altas (>1000 ind/1000 ml alga) en toda la Península; los isópodos mostraron las mayores densidades en el Atlántico, mientras que los tanaidáceos, cumáceos y decápodos fueron más abundantes en el Mediterráneo. Entre los moluscos, los gasterópodos mostraron abundancias mayores en el Atlántico, mientras que los bivalvos dominaron en el Mediterráneo. Teniendo en cuenta que todas las estaciones seleccionadas no tenían influencia antrópica importante, los patrones de abundancia obtenidos podrían explicarse en base a diferencias naturales en la temperatura del agua, oxígeno, conductividad y turbidez, existiendo un gradiente transicional entre taxones de aguas más cálidas (del norte de Africa y del Mediterráneo) y taxones de aguas más frías (del Mar del Norte y el Ártico)