El concepto de inestabilidad espinodal y su importancia científica

El concepto de estabilidad es clave para el entendimiento de la Química y de la mayoría de los fenómenos relevantes en sus diferentes disciplinas. Pero en esta conferencia se tratará el concepto de límite de estabilidad, o inestabilidad espinodal, y se destacará su importancia conceptual. Existen ejemplos clásicos en los que aparece el concepto espinodal, tales como la separación de fases (p. ej. al estudiar la ecuación de van der Waals) o el fenómeno de la nucleación. Sin embargo, estamos ante un concepto que suele pasar desapercibido, por no decir que es bastante desconocido. A pesar del aparente enfoque metodológico de la conferencia, el grueso de la exposición se centrará en explicar una serie de casos científicos de muy diversa índole donde el concepto de instabilidad espinodal permite establecer modelos de referencia universales y explicar de forma simple y coherente muchas evidencias experimentales.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Multianalytical characterization of Lanzarote basalts as a regolith simulant and lunar habitability resource

La búsqueda de análogos terrestres es crucial para el desarrollode futuras bases lunares permanentes o semipermanentes. Los análogos terrestres son regiones donde es posible probar no solo instrumental científico, sino también las capacidades de los astronautas en un entorno que, por su contexto geológico, geomorfológico, mineralógico, geoquímico, etc es similar al que podemos encontrar en Marte, la Luna e incluso asteroides. Este trabajo se ha centrado en la realización de una caracterización multianalítica de tres regiones de Lanzarote (Maciot, Tao y Lavas de Timanfaya) a través del empleo de diferentes técnicas geoquímicas y petrofísicas. Los resultados han sido comparados con los datos aportados por otros autores sobre muestras traídas de las misiones Apolo. Esto ha permitido determinar la analogía existente entre las regiones de estudio y la región de alunizaje del Apolo 14 conocida como Fra-Mauro. Además, se ha podido concluir qué recursos son potencialmente extraíbles del regolito lunar y su función en una futura base semipermanente. Por último, se propone la posibilidad de elaborar el primer simulante regolítico lunar usando basalto de Lanzarote.The search for Terrestrial Analogues is essential for the development of future permanent or semi-permanent lunar bases. Terrestrial Analogues are zones where it is possible to probe not only scientific instruments but also to other astronaut capabilities in an environment that is similar to the geological context, geomorphology, mineralogical, geochemistry, etc that we can find on Mars, the Moon and even asteroids. This work has focused on a multi-analytical characterization of three Lanzarote regions (Maciot, Tao y Lavas de Timanfaya), with different geochemical and petrophysical test. These results have been compared with data provided by other authors on samples brought from the Apollo missions. This has allowed to determine the analogy between the study regions and the Apollo 14 moon landing site known as Fra-Mauro formation. In addition, it is concluded which resources are potentially extractable from the Moon regolith and its function in a future semipermanent lunar base. Finally, it is proposed the possibility of developing the first Spanish lunar soil simulant through one of the Lanzarote basalts.Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

LZS-1, Lanzarote (Canary Island, Spain) lunar (Apollo 14) basaltic soil simulant

The search for Terrestrial Analogues is essential for the development of future permanent or semi-permanent lunar bases. Terrestrial Analogues are zones where it is possible to probe not only scientific instruments, but also other astronaut capabilities in an environment that is similar to the geological context, geomorphology, mineralogy, geochemistry, etc. that we can find on Mars, the Moon and even asteroids. This work has focused on a multi-analytical characterization of Peñas de Tao geosite basalts in Lanzarote (Canary Islands, Spain). This characterization starts from a field campaign in which 3000 g of basalt rocks were selected. Subsequently, they were analysed by different techniques to determine their composition at a mineralogical and geochemical level, and the results were compared with data from other lunar simulants and from the Apollo 14 mission. After that, a set of petrophysical tests was carried out in order to determine its physical properties and evaluate its capacity as an analogous material for use in situ as a resource for further geological and astrobiological (future lunar habitability) essays

Investigating Piezochromic Properties of πconjugated Materials: a combined Raman and DFT Study

Π-conjugated materials have been studied for decades due to their great interest in organic electronics. Among them, piezochromic materials, which exhibit color changes resulting from external pressure or mechanical grinding, become very attractive from a scientific viewpoint owing to their potential applications as pressure-sensing and opticalrecording systems1. The main target of the present work is to develop a joint experimental and theoretical approach able to deliver crucial information for the understanding of the structural effects causing piezochromic changes. To this end, we will focus our attention on two families of -conjugated materials with potential application as sensors. The first one is a family of 9,10-Bis((E)-n(pyrid-2-yl)vinyl) anthracene, BPnVA (n=2 orto-,3 metha- and 4 para-) compounds, see Figure 1. Interestingly, these three compounds with varying position of the nitrogen on the external pyridyl group exhibit different molecular packing modes. Grinding and the application of external pressure on the powder also led to a strong change in their photoluminescence color.2 The second familiy is based on the N,N’-Bis-Boc-3,3’-di(pyren-1yl)-2,2’-biindole compound (compound 1c in Figure 1) which also shows photoluminescence under pressure application. However, the molecular packing induced by this phenomenon is still under study 3. In both cases, it will be also very interesting to determine how temperature affects the vibrational structure of these systems.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Analysis of the ordinary chondrite of Dalgety Downs (L4): Mineralogy, geochemistry and Raman spectroscopy

El meteorito de Dalgety Downs, hallado en el Desierto de Australia Occidental, es una condrita ordinaria muy poco estudiada, que sin embargo contiene una valiosa información acerca de la evolución de la materia primitiva del Sistema Solar y los procesos que le afectan. Este ejemplar presenta unas características texturales, mineralógicas y geoquímicas en la matriz y cóndrulos que revelan procesos metamórficos de temperaturas intermedias y eventos de impacto moderados, además de una intensa alteración desarrollada durante su entrada en la atmósfera terrestre y su posterior exposición al clima, en lo que se define como la costra de fusión. Entre los métodos empleados en este estudio destaca la espectroscopía Raman como herramienta de identificación mineralógica, técnica que ha demostrado una gran precisión en materiales geológicos y que será empleada en próximas misiones espacialesThe Dalgety Downs meteorite, found in the Western Australian Desert, is a poorly studied ordinary chondrite, that however contains valuable information about the Solar System primitive matter evolution and the processes that affect it. This specimen exhibits textural, mineralogical and geochemical characteristics in matrix and chondrules that reveal metamorphic processes of intermediate temperatures and moderate impact events, in addition to an intense alteration developed during its entry into the terrestrial atmosphere and later exposure to climate, in what is defined as the fusion crust. Among the methods employed in this study, Raman spectroscopy highlights as a mineralogical identification tool, a technique of high precision in the analysis of geological materials and that is expected to be used in upcoming space mission

Charge analysis in (RE)CrO4 scheelites by combined Raman spectroscopy and computer simulations

The quest for structure-property relationships in scheelite-type (RE)CrO4 compounds (where RE is a rare earth element) is a difficult task due to the number of exceptions found in RE empirical trends and the uncommon Cr(V) oxidation state. In this work, we experimentally and computationally analyse how the stretching vibrational frequencies ν1(Ag) and ν3(Eg) associated with the [CrO4] tetrahedral units evolve in the (RE)CrO4 crystal family (RE ¼ Nd, Gd, Dy, Ho, and Lu). Since previously reported Cr–O distances and volume changes along with the RE series are not sufficiently accurate to explain the monotonic decrease observed for the ν1(Ag) and ν3(Eg) frequencies, a deeper analysis was performed involving the well-known fact that the bond strength (force constant) decreases as the interatomic distance increases. Our results demonstrates that structural and spectroscopic parameters can be reconciled with classical solid state chemistry ideas when charge effects are considered. This analysis provides a new method for predicting chromium oxidation states from Raman spectroscopy that can be generalised to the study of other crystal families