Lanthanide nickelates for their application on Solid Oxide Cells

High-temperature technologies like solid oxide cells (SOC) have been employed to provide power-to-fuel and vice versa for energy conversion and storage. These technologies are a work in progress due to durability and compatibility issues between components at high temperatures. For this reason, the pursuit of optimal physical, mechanical, and chemical properties of SOC materials at lower temperatures has become more diligent. Finding suitable air electrodes has become one of the more notable obstacles to complete implementation in the industry. One of the most recent alternatives is the use of lanthanide nickelates with the Ruddlesden-Popper (RP), Lnn+1NinO3n±1 (Ln = La, Nd or Pr), and perovskite, LnNiO3-δ, structures. These materials present fast ionic and electronic transport, as well as flexible oxygen stoichiometry that makes them compelling for this purpose. As part of an ongoing study on alternative air electrode advanced materials, this review is focused on documenting the relevant findings of RP nickelates over the years, especially focusing on the current status in research and development while comparing the electrochemical performance of nickelate air electrodes

Reversible operation performance of microtubular solid oxide cells with a nickelate-based oxygen electrode

This paper describes the reversible operation of a highly efficient microtubular solid oxide cell (SOC) with a nickelate-based oxygen electrode. The fuel cell was composed of a microtubular support of nickel and yttria stabilized zirconia (Ni-YSZ), an YSZ dense electrolyte, and a double oxygen electrode formed by a first composite layer of praseodymium nickelate (PNO) and gadolinium-doped ceria (CGO) and a second one of PNO. A good performance of the cell was obtained at temperatures up to 800 °C for both fuel cell (SOFC) and electrolysis (SOEC) operation modes, specially promising in electrolysis mode. The current density in SOEC mode at 800 °C is about -980 mA cm-2 at 1.2V with 50% steam. Current density versus voltage curves (j-V) present a linear behavior in the electrolysis mode, with a specific cell area resistance (ASR) of 0.32 O cm-2. Durability experiments were carried out switching the voltage from 0.7V to 1.2V. No apparent degradation was observed in fuel cell mode and SOEC mode up to a period of about 100 h. However, after this period especially in electrolysis mode there is an accumulated degradation associated to nickel coarsening, as confirmed by SEM and EIS experiments. Those results confirm that nickelate based oxygen electrodes are excellent candidates for reversible SOCs. © 2019 Hydrogen Energy Publications LL

A taxonomy for key performance indicators management

In recent years, research on Key Performance Indicators (KPIs) management has grown exponentially, giving rise to a multitude of heterogeneous approaches addressing any aspect concerning it. In this paper, we plot the landscape of published works related with KPIs management, organizing and synthesizing them by means of a unified taxonomy that encompasses the aspects considered by other proposals, and it captures the overall characteristics of KPIs. Since most of the literature centers on the definition of KPIs, we mainly focus on such an aspect of KPIs management. Our work is intended to provide remarkable benefits such as enhancing the understanding of KPIs management, or helping users decide about the most suitable solution for their requirements

APPLIED MINERALOGY TO THE DEFINITION OF THE TYPE OF REFRACTORINESS IN EL ZANCUDO GOLD MINE, ANTIOQUIA, COLOMBIA

The physic and chemistry characteristics that give to the El Zancudo gold mine certain degree of refractoriness, were determined, regarding some initial bases about the problems that could occur at the moment of developing a conventional benefit system. The main metallic minerals found are arsenopyrite, pyrite and in smaller proportions sphalerite, tetrahedrite, boulangerite, galena, chalcopyrite, jamesonita, pyrrhotite and gold. Around 80% of the grains of gold are less than 30μm size, additionally, gold appears principally as small inclusions (<10μm) in pyrite (36%) and arsenopyrite (6,3%), which involve problems of liberation in the grinding process, requiring some type of pretreatment before cyanuration processes; on the other hand, the existence of silver within the gold grains (28 Wt.%), it could generate secondary silver sulfur coating and it becomes in a impermeable barrier for the cyanide. The existence of minerals like arsenopyrite and the pyrite can generate problems during the cyaniding due to the formation of different sulfur and arsenic composes which consume both oxygen and cyanide; all these factors cause that the velocity of dissolution be diminished. Finally, the sericite can generate a preg-robbing effect, diminishing the efficiency of the cyaniding process.   Key words: Refractoriness, Applied mineralogy, Gold, Sulphides, El Zancudo.Las características físicas y químicas que le imprimen cierto grado de refractariedad al depósito de la mina de oro El Zancudo, fueron determinadas, planteando algunas bases iniciales sobre los problemas que podrían presentarse en el momento de desarrollarse un sistema convencional de beneficio. Los principales minerales de mena encontrados son, arsenopirita, pirita y en menor proporción, esfalerita, tetraedrita, boulangerita y galena y en un porcentaje menor de 1%, calcopirita, jamesonita, pirrotita y oro. Como minerales pertenecientes a la ganga se encuentra cuarzo, carbonatos y minerales arcillosos, como sericita y saussurita. Alrededor del 80% de los granos de oro se encuentran por debajo de 30μm, adicionalmente, el oro se presenta principalmente como pequeñas inclusiones (<10μm) en pirita (36%) y arsenopirita (6,3%), lo cual implica problemas liberación durante la molienda, requiriendo algún tipo de pretratamiento antes de la cianuración; de otro lado, la presencia de plata en los granos de oro (~ 28 Wt.%), puede hacer que se generen capas de sulfuro de plata secundarios, convirtiéndose en una barrera impermeable al cianuro. La presencia de minerales tales como arsenopirita y la pirita, pueden generar problemas durante la cianuración debido a la formación de diferentes compuestos de azufre y arsénico que consumen tanto oxígeno como cianuro y, por otro lado, la pirrotita, aunque se encuentra en poca cantidad, puede formar compuestos que se adsorben sobre la superficie del oro; todos estos factores hacen que la velocidad de disolución se vea disminuida. Finalmente, la sericita, puede generar un efecto preg-robbing, disminuyendo la eficiencia del proceso de cianuración.   Palabras clave: Refractariedad, mineralogía aplicada, oro, sulfuros, El Zancudo.     &nbsp

La reincidencia delictiva: Sus consecuencias jurídicas (Quid de la agravación de la pena por reincidencia y de la accesoria de reclusión por tiempo indeterminado para multirreincidentes. Pautas para su adecuada regulación, a la luz de los principios de la

La investigación se refiere centralmente a la determinación de la legitimidad o ilegitimidad de las consecuencias jurídicas que se atribuyen al estado de reincidencia y de plurirreincidencia en el Derecho Penal. Tales cuestiones han adquirido especial actualidad en la última década, a causa de diversos precedentes judiciales que por vía de la declaración de inconstitucionalidad de reglas de la legislación penal y/o con apelación a principios penales, han dejado de lado la aplicación de éstas; asimismo el proyecto de nuevo Código Penal de 2006 eliminaba la institución jurídica en examen, que había sido constante en las sucesivos regímenes legales argentinos.

Collective dynamics of internal states in a Bose gas

Theory for the Rabi and internal Josephson effects in an interacting Bose gas in the cold collision regime is presented. By using microscopic transport equation for the density matrix the problem is mapped onto a problem of precession of two coupled classical spins. In the absence of an external excitation field our results agree with the theory for the density induced frequency shifts in atomic clocks. In the presence of the external field, the internal Josephson effect takes place in a condensed Bose gas as well as in a non-condensed gas. The crossover from Rabi oscillations to the Josephson oscillations as a function of interaction strength is studied in detail.Comment: 18 pages, 2 figure

Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.