1,968 research outputs found
Advancing towards a Practical Magnesium Ion Battery
A post-lithium battery era is envisaged, and it is urgent to find new and sustainable systems for energy storage. Multivalent metals, such as magnesium, are very promising to replace lithium, but the low mobility of magnesium ion and the lack of suitable electrolytes are serious concerns. This review mainly discusses the advantages and shortcomings of the new rechargeable magnesium batteries, the future directions and the possibility of using solid electrolytes. Special emphasis is put on the diversity of structures, and on the theoretical calculations about voltage and structures. A critical issue is to select the combination of the positive and negative electrode materials to achieve an optimum battery voltage. The theoretical calculations of the structure, intercalation voltage and diffusion path can be very useful for evaluating the materials and for comparison with the experimental results of the magnesium batteries which are not hassle-free
Magnesium Deintercalation From the Spinel-Type MgMn2-yFeyO4 (0.4≤y≤2.0) by Acid-Treatment and Electrochemistry
Rechargeable magnesium batteries attract lots of attention because of their high safety and low cost compared to lithium batteries, and it is needed to develop more efficient electrode materials. Although MgMn2O4 is a promising material for the positive electrode in Mg rechargeable batteries, it usually exhibits poor cyclability. To improve the electrochemical behavior, we have prepared nanoparticles of MgMn2-yFeyO4. The XRD results have confirmed that when Mn3+ (Jahn-Teller ion) ions are replaced by Fe3+ (non-Jahn-Teller ion), the resulting MgMn2-yFeyO4 is a cubic phase. The structure and theoretical voltage are theoretically calculated by using the DFT method. The obtained samples have been chemically treated in acid solution for partial demagnesiation, and it is observed that the presence of iron inhibits the deinsertion of Mg through disproportionation and favors the exchange reaction. The electrochemical behavior in non-aqueous magnesium cells has been explored
Fast degenerate double proton transfer in the solid state between two indazolinone tautomers
The neutral dimer formed by 4,6-difluoro-1H,2H-indazolin-3-one and 3-hydroxy-4,6-difluoro-1H-indazole linked by two hydrogen bonds presents a very fast intermolecular double proton transfer in the solid state (ISSPT). The combined use of crystallography, solid state NMR and DFT [B3LYP/6-311++G(d,p)] calculations supports this interesting observation and allows us to estimate a barrier of about 20 kJ mol-1. © 2010 The Royal Society of Chemistry.Peer Reviewe
Comparación del movimiento de alcance entre sujetos Sanos y Patológicos en Neurorrehabilitación Funcional de Extremidad Superior
El presente trabajo de investigación tiene como propósito principal realizar una comparación del movimiento de alcance entre sujetos aquejados de Daño Cerebral Adquirido y el correspondiente patrón de normalidad. La finalidad de esta comparación es detectar los déficits motores que permitan posteriormente emitir una valoración funcional del movimiento como parte de un método de evaluación objetiva de la función motora. La comparación del movimiento se basa en las medidas de parámetros espaciales y de similitud. En este trabajo se han utilizado modelos de movimiento de sujetos sanos en ejecuciones de Actividades de Vida Diaria (e.g. 'servir agua de una jarra'), como punto de referencia para encontrar diferencias relevantes con respecto a los datos de movimiento de cuatro pacientes bajo un proceso de Neurorrehabilitación Funcional de Extremidad Superi
Review and new perspectives on non-layered manganese compounds as electrode material for Sodium-Ion batteries
After more than 30 years of delay compared to lithium-ion batteries, sodium analogs are now emerging in the market. This is a result of the concerns regarding sustainability and production costs of the former, as well as issues related to safety and toxicity. Electrode materials for the new sodium-ion batteries may contain available and sustainable elements such as sodium itself, as well as iron or manganese, while eliminating the common cobalt cathode compounds and copper anode current collectors for lithium-ion batteries. The multiple oxidation states, abundance, and availability of manganese favor its use, as it was shown early on for primary batteries. Regarding structural considerations, an extraordinarily successful group of cathode materials are layered oxides of sodium, and transition metals, with manganese being the major component. However, other technologies point towards Prussian blue analogs, NASICON-related phosphates, and fluorophosphates. The role of manganese in these structural families and other oxide or halide compounds has until now not been fully explored. In this direction, the present review paper deals with the different Mn-containing solids with a non-layered structure already evaluated. The study aims to systematize the current knowledge on this topic and highlight new possibilities for further study, such as the concept of entatic state applied to electrodes
Nearby supernova host galaxies from the CALIFA survey: II. Supernova environmental metallicity
The metallicity of a supernova progenitor, together with its mass, is one of the main parameters that can rule the progenitor's fate. We present the second study of nearby supernova (SN) host galaxies (0.005 10 dex) by targeted searches. We neither found evidence that the metallicity at the SN location differs from the average metallicity at the galactocentric distance of the SNe. By extending our SN sample with published metallicities at the SN location, we are able to study the metallicity distributions for all SN subtypes split into SN discovered in targeted and untargeted searches. We confirm a bias toward higher host masses and metallicities in the targeted searches. By combining data from targeted and untargeted searches, we found a sequence from higher to lower local metallicity: SN Ia, Ic, and II show the highest metallicity, which is significantly higher than those of SN Ib, IIb, and Ic-BL. Our results support the scenario according to which SN Ib result from binary progenitors. Additionally, at least part of the SN Ic are the result of single massive stars that were stripped of their outer layers by metallicity-driven winds. We studied several proxies of the local metallicity that are frequently used in the literature and found that the total host metallicity allows estimating the metallicity at the SN location with an accuracy better than 0.08 dex and very small bias. In addition, weak AGNs that cannot be seen in the total spectrum may weakly bias (by 0.04 dex) the metallicity estimate that is derived from the galaxy-integrated spectrum. © ESO, 2016.This work was partly funded by FCT with the research grant PTDC/CTE-AST/112582/2009. Support for L.G. is partially provided by FCT, by CONICYT through FONDECYT grant 3140566, and from the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC12009, awarded to The Millennium Institute of Astrophysics (MAS). V.S. acknowledges financial support from Fundacao para a Ciencia e a Tecnologia (FCT) under program Ciencia 2008. C.J.W. acknowledges support through the Marie Curie Career Integration Grant 303912.Peer Reviewe
In situ Raman characterization of minerals and degradation processes in a variety of cultural and geological heritage sites
Wetest the capabilities of in situ Raman spectroscopy for non-destructive analysis of degradation processes in invaluable
masterpieces, as well as for the characterization of minerals and prehistoric rock-art in caves. To this
end, we have studied the mechanism of decay suffered by the 15th-century limestone sculptures that decorate
the retro-choir of Burgos Cathedral (N Spain). In situ Raman probe detected hydrated sulfate and nitrateminerals
on the sculptures, which are responsible for the decay of the original limestone. In addition, in situ Raman analyses
were performed on unique speleothems in El Soplao Cave (Cantabria, N Spain) and in the Gruta de las
Maravillas (Aracena, SWSpain). Unusual cavemineralswere detected in El Soplao Cave, such as hydromagnesite
(Mg5(CO3)4(OH)2·4H2O), as well as ferromanganese oxides in the black biogenic speleothems recently discovered
in this cavern. In the Gruta de las Maravillas, gypsum (CaSO4·2H2O) was identified for the first time, as
part of the oldest cave materials, so providing additional evidence of hypogenic mechanisms that occurred in
this cave during earlier stages of its formation. Finally, we present preliminary analyses of several cave paintings
in the renowned “Polychrome Hall” of Altamira Cave (Cantabria, N. Spain). Hematite (Fe2O3) is the most abundant
mineral phase, which provides the characteristic ochre-reddish color to the Altamira bison and deer paintings.
Thus, portable Raman spectroscopy is demonstrated to be an analytical technique compatible with
preserving our cultural and natural heritage, since the analysis does not require physical contact between the
Raman head and the analyzed items
The Holocene volcanism of Gran Canaria (Canary Islands, Spain)
This work presents the first detailed map of the Holocene eruptions of Gran Canaria (Canary Islands, Spain). It provides complete and detailed information for all 24 Holocene eruptions of Gran Canaria, improving the knowledge of this recent volcanism and the assessment of volcanic hazards on the island. This map is a synthesis of collated and interpreted field data and topographic maps. We have integrated information obtained from: (1) detailed geological field surveys, (2) morphometric analysis of eruptive deposits, (3) high-resolution digital elevation models, and (4) aerial photographs
Dysfunctional profile for patients in physical neurorehabilitation of upper limb
This paper proposes a first approach to Objective Motor Assessment (OMA) methodology. Also, it introduces the Dysfunctional profile (DP) concept. DP consists of a data matrix characterizing the Upper Limb (UL) physical alterations of a patient with Acquired Brain Injury (ABI) during the rehabilitation process. This research is based on the comparison methology of UL movement between subjects with ABI and healthy subjects as part of OMA. The purpose of this comparison is to classify subjects according to their motor control and subsequently issue a functional assessment of the movement. For this purpose Artificial Neural Networks (ANN) have been used to classify patients. Different network structures are tested. The obtained classification accuracy was 95.65%. This result allows the use of ANNs as a viable option for dysfunctional assessment. This work can be considered a pilot study for further research to corroborate these results
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