Multiparameter quantum groups, bosonizations and cocycle deformations García, Gastón Andrés The multiparameter quantized enveloping algebras Uq(gA) constructed by Pei, Hu and Rosso [Quantum affine algebras, extended affine Lie algebras, and their applications, 145–171, Amer. Math. Soc., Providence, 2010] are presented as the pointed Hopf algebras Ue(Dred, `) defined by Andruskiewitsch and Schneider [Ann. of Math. (2) 171 (2010), 375–417]. The result is applied to show that under a certain assumption Uq(gA) depends, up to cocycle deformation, on only one parameter in each connected component of the associated Dynkin diagram. In the special case that gA is simple, this was already shown by Pei, Hu and Rosso in an alternative way.

Cetopsorhamdia iheringi (Siluriformes, Heptapteridae): a new record for the freshwater ichthyofauna of Argentina; Cetpsorhamdia iheringi (Siluriformes, Heptapteridae): un nuevo registro para la ictiofauna de agua dulce de Argentina Benitez, Mauricio Fabián; Teran, Guillermo Enrique; Alonso, Felipe; Aguilera, Gaston; Mirande, Juan Marcos Cetopsorhamdia es un género de bagres neotropicales con amplia distribución en las principales cuencas de Sudamérica. Aquí reportamos el primer registro de Cetopsorhamdia iheringi en la Argentina y discutimos sobre la serie tipo de la especie.; Cetopsorhamdia is a genus of Neotropical catfishes with a broad distribution in the main drainages of South America. Herein we report the first record of Cetopsorhamdia iheringi in Argentina and comment on the type series of the species.

Latitudinal and altitudinal patterns of plant community diversity on mountain summits across the tropical Andes Cuesta, Francisco; Muriel, Priscilla; Llambí, Luis Daniel; Halloy, Stephan; Aguirre, Nikolay; Beck, Stephan; Carilla, Julieta; Meneses, Rosa Isela; Cuello, Ana Soledad; Grau, Alfredo; Gámez, Luis E.; Irazábal, Javier; Jácome, Jorge; Jaramillo, Ricardo; Ramírez, Lirey; Samaniego, Natalia; Suárez Duque, David; Thompson, Natali; Tupayachi, Alfredo; Viñas, Paul; Yager, Karina; Becerra, María T.; Pauli, Harald; Gosling, William D. The high tropical Andes host one of the richest alpine floras of the world, with exceptionally high levels of endemism and turnover rates. Yet, little is known about the patterns and processes that structure altitudinal and latitudinal variation in plant community diversity. Herein we present the first continental-scale comparative study of plant community diversity on summits of the tropical Andes. Data were obtained from 792 permanent vegetation plots (1 m2) within 50 summits, distributed along a 4200 km transect; summit elevations ranged between 3220 and 5498 m a.s.l. We analyzed the plant community data to assess: 1) differences in species abundance patterns in summits across the region, 2) the role of geographic distance in explaining floristic similarity and 3) the importance of altitudinal and latitudinal environmental gradients in explaining plant community composition and richness. On the basis of species abundance patterns, our summit communities were separated into two major groups: Puna and Páramo. Floristic similarity declined with increasing geographic distance between study-sites, the correlation being stronger in the more insular Páramo than in the Puna (corresponding to higher species turnover rates within the Páramo). Ordination analysis (CCA) showed that precipitation, maximum temperature and rock cover were the strongest predictors of community similarity across all summits. Generalized linear model (GLM) quasi-Poisson regression indicated that across all summits species richness increased with maximum air temperature and above-ground necromass and decreased on summits where scree was the dominant substrate. Our results point to different environmental variables as key factors for explaining vertical and latitudinal species turnover and species richness patterns on high Andean summits, offering a powerful tool to detect contrasting latitudinal and altitudinal effects of climate change across the tropical Andes.

Indicadores de soledad y aislamiento en adolescentes de dos provincias del Norte Argentino; Indicators of Loneliness and Isolation in Adolescents from two Provinces in the North of Argentina Lacunza, Ana Betina; Coronel, Claudia Paola; Contini, Evangelina Norma; Martin, Lourdes; Medina, Susana El objetivo fue evaluar indicadores de soledad y aislamiento autopercibida por 412 adolescentes escolarizados residentes en Tucumán y Santiago del Estero (Argentina). Se trató de un estudio comparativo, transversal con muestreo accidental. Se administró el Cuestionario de Aislamiento y Soledad (CAS), la Batería de Socialización (BAS-3) y una encuesta sociodemográfica. El 28% manifestaba comportamientos riesgosos en soledad y 25% en aislamiento. Un 7% refería comportamientos con mayor propensión psicopatológica. El grupo con riesgo en soledad presentaba déficits en habilidades sociales: menor consideración con los demás, menor liderazgo y mayor retraimiento respecto a sus pares sin riesgo; los de riesgo en aislamiento mostraba menor autocontrol. Los datos descriptos identificaron indicadores de vulnerabilidad en población adolescente escolarizada y son valiosos para diseñar estrategias de intervención como prevención.; The aim of this paper was to evaluate indicators of self-perceived loneliness and isolation by 412 adolescents attending school and living in Tucumán and Santiago del Estero (Argentina). A comparative, transversal research was carried out and the technique used was accidental sampling. The loneliness and isolation questionnaire (CAS), BAS-3 Socialization Battery and a sociodemographic survey were administered. 28% evidenced risky behaviour in loneliness and 25% in isolation. Within this group, 7% presented a higher psychopathological tendency. The group in loneliness at risk showed lack of social skills related to less consideration for others, a lower degree of leadership and higher degree of withdrawal. On the other hand, the group in isolation at risk evidenced a reduced level of self-control. The data described made it possible to identify indicators of vulnerability in adolescent population who attend school and they proved to be valuable to design intervention strategies as prevention.

La maduración visomotora en niños y adolescentes: Una investigación para actualizar normas; Visuomotor maturation in children and adolescents: An investigation to update norms Contini, Evangelina Norma; Lacunza, Ana Betina; Coronel, Claudia Paola; Caballero, Silvina Valeria La maduración visomotora es una función universal, todos los niños a medida que aumenta su edad cronológica adquieren mayor maduración viso motora y, a su vez, se caracteriza por la diversidad, influida por el contexto. Objetivos: a) describir el nivel de madurez visomotora de niños y adolescentes escolarizados del Gran San Miguel de Tucumán, según edad y nivel socioeconómico (NSE), b) generar normas actualizadas del Test guestáltico visomotor de Bender y c) comparar los baremos obtenidos en la actualidad con los de 1995 para población de Tucumán. Participantes: 945 sujetos del Gran San Miguel de Tucumán, entre 5 y 12 años. Se trata de un estudio cuantitativo, comparativo, transversal, con muestreo no probabilístico intencional. Se realizaron análisis descriptivos del puntaje error y análisis univariados considerando edad y NSE. Se halló que la cantidad de errores tendían a disminuir a medida que aumentaba la edad y se encontraron diferencias estadísticas significativas en la combinación NSE y edad. Se establecieron percentiles para toda la muestra. Se efectuaron prueba t de Student para muestras independientes para comparar puntajes error del baremo Tucumán 1995 y los del presente estudio. Este trabajo aporta información valiosa al diagnóstico de la evaluación psicológica infantojuvenil.; Visuomotor maturation is a universal function. As children’s chronological age advances so does their visuomotor maturation. Such maturation is characterized by diversity, which is, in turn, infuenced by context. Objectives: a) to describe the level of visuomotor maturity of children schooled at San Miguel de Tucuman, taking into consideration age and socioeconomic status (NSE), b) to set updated norms on Bender Gestalt Test and c) to compare the recently obtained scale with that of the year 1995 for the population in Tucumán. Participants: 945 subjects from San Miguel de Tucuman, aged 5 – 12. This is a quantitative, comparative, cross-sectional, non-probability sampling based study. A descriptive analysis of the error score and a univariate analysis considering the informants’ age and socioeconomic status were carried out. Findings showed that the older the children were, the less mistakes they tended to make. Additionally, meaningful statistical differences were found when both factors namely, age and socioeconomic status, were considered. Percentiles weree stablish ed for the whole sample. Student’s t-tests for independent samples were performed so as to compare error scores from the scale Tucuman 1995 with those of the current study. This piece of research offers valuable information for the diagnosis of child and adolescent psychological assessment.

Algo más que filmes para la Corona: John Grierson y el Movimiento Documental Británico; Something More than just Films for the Crown. John Grierson and the British Documentary Film Movement Campo, Javier Alberto El primer movimiento cinematográfico en la historia del cine documental fue uno de los más controversiales, inasibles y malinterpretados de todos. El Movimiento Documental Británico, surgido al amparo de instituciones estatales, fue justamente definido más corrientemente por su vinculación con los intereses de la Corona y el gobierno inglés que por su aporte al desarrollo del cine documental durante sus primeros veinte años de vida. En buena medida las manifestaciones de los realizadores protagonistas de esta historia (y no las representaciones configuradas por los mismos) otorgaron materia a las malas interpretaciones posteriores. Pero en este estudio incluiremos lo que pocos: las películas. Es allí en donde los estudios sobre el Movimiento Británico no se pararon más que circunstancialmente. Es allí también en donde encontraremos los elementos que nos permitirán superar el umbral de «lo pedagógico institucional» de este conjunto de filmes para recuperar la real envergadura de los trabajos de Grierson y sus muchachos. Es allí en donde, por último, como dice Brian Winston: «Grierson y sus seguidores pusieron los problemas sociales con una puesta “poética”» (1995:55).; The first film movement in the history of documentary cinema was one of the most controversial, elusive and misunderstood of all. The British Documentary Film Movement, which emerged supported by state institutions, was precisely more commonly defined by its links with the interests of the Crown and the British government, than by its contribution to the development of documentary film during its first twenty years of life. To a great extent, demonstrations by protagonist filmmakers of this history (and not the representations set by them) granted subject to bad subsequent interpretations. In this study, however, we will deal with what few have dealt with before: the movies. This is what studies on the British Movement only analyzed circumstantially. It is in movies where we find the elements that allow us to overcome the threshold of «the pedagogical and institutional» in this set of films, to recover the actual importance of the work of Grierson and his boys. This is where, finally, as Brian Winston says: «Grierson and his followers portray social problems with a “poetic” staging» (1995:55).

A Structural Analysis of topic ontologies Xamena, Eduardo; Brignole, Nélida Beatriz; Maguitman, Ana Gabriela DMOZ is the largest human-edited topic ontology available on the Web. This article studies the structural properties of the DMOZ graph. A number of global and local properties of this graph and the subgraphs resulting from isolating edges of different types are examined by means of metrics commonly used in complex network analysis. In particular, we investigate the presence of various features that characterize small-world networks. This analysis is complemented by examining other characteristics of the graphs such as connectivity and centrality measures. The connectivity and centrality patterns are further studied by means of visualizations of the graphs’ k-core decomposition and a selection of strongly connected components. Several non-trivial regularities that are also encountered in other artificial and natural complex networks provide a general picture of this large human-edited topic ontology. This analysis is of major pragmatic interest as it allows a better understanding of notions such as navigability among topics, hierarchical structure and topic cohesiveness, which are of great importance in the design of topic ontologies.

Actualistic Taphonomy in Argentina: Current Status of the Research and Future Perspectives Alunni, Daniela Verónica; Alvarez, María Clara This short article reviews the state of the art of actualistic taphonomicresearch in Argentina. Taphonomic studies with actualistic approaches are undergoing substantial developments in our country. Several topics are being studying by using different methods and techniques. From this brief analysis, we consider that this discipline will continue its strong growth in the future.

Thermal buffering capacity of the germination phenotype across the environmental envelope of the Cactaceae Seal, Charlotte E.; Daws, Matthew I.; Flores, Joel; Ortega Baes, Francisco Pablo; Galindez, Guadalupe; León Lobos, Pedro; Sandoval, Ana; Ceroni Stuva, Aldo; Ramírez Bullón, Natali; Dávila-Aranda, Patricia; Ordoñez Salanueva, Cesar A.; Yáñez Espinosa, Laura; Ulian, Tiziana; Amosso, Cecilia; Zubani, Lino; Torres Bilbao, Alberto; Pritchard, Hugh W. Recruitment from seeds is among the most vulnerable stage for plants as global temperatures change. While germination is the means by which the vast majority of the world's flora regenerate naturally, a framework for accurately predicting which species are at greatest risk of germination failure during environmental perturbation is lacking. Taking a physiological approach, we assess how one family, the Cactaceae, may respond to global temperature change based on the thermal buffering capacity of the germination phenotype. We selected 55 cactus species from the Americas, all geo-referenced seed collections, reflecting the broad environmental envelope of the family across 70° of latitude and 3700 m of altitude. We then generated empirical data of the thermal germination response from which we estimated the minimum (Tb), optimum (To) and ceiling (Tc) temperature for germination and the thermal time (θ50) for each species based on the linearity of germination rate with temperature. Species with the highest Tb and lowest Tc germinated fastest, and the interspecific sensitivity of the germination rate to temperature, as assessed through θ50, varied tenfold. A left-skewed asymmetry in the germination rate with temperature was relatively common but the unimodal pattern typical of crop species failed for nearly half of the species due to insensitivity to temperature change at To. For 32 fully characterized species, seed thermal parameters correlated strongly with the mean temperature of the wettest quarter of the seed collection sites. By projecting the mean temperature of the wettest quarter under two climate change scenarios, we predict under the least conservative scenario (+3.7°C) that 25% of cactus species will have reduced germination performance, whilst the remainder will have an efficiency gain, by the end of the 21st century.

A structural and spectroscopic study on carquejol, a relevant constituent of the medicinal plant Baccharis trimera (Less.) DC. (Asteraceae) Minteguiaga, Manuel; Dellacassa, Eduardo; Iramain, Maximiliano Alberto; Catalan, Cesar Atilio Nazareno; Brandan, Silvia Antonia Carquejol and its acetate are monoterpenoids based on the rare o-menthane skeleton and distinctive components of the essential oil from Baccharis trimera. Carquejol was characterized by using Fourier Transform infrared (FT-IR) and Raman (FT-Raman), Ultraviolet–Visible (UV–Visible), Electronic Circular Dichroism (ECD), Mass, Hydrogen and Carbon Nuclear Magnetic Resonance (1H and 13C NMR) and 2D 1H–1H gCOSY, 1H–13CgHSQC, 1H–13CgHMBC spectroscopies. Due to the chirality of this monoterpenoid, six different structures were analysed, of which only four showed higher populations and minimal energies. The natural bond orbital (NBO), atoms in molecules (AIM), Merz-Kollman (MK) charges, molecular electrostatic potentials (MEP) and frontier orbitals studies were performed in order to evaluate their structural, electronic, topological and vibrational properties. All calculations were performed by using the hybrid B3LYP method and the 6-31G* and 6-311++G** basis sets. The comparison of the experimental ECD spectra with the corresponding theoretical ones confirm the (4S,5R) configuration assigned to carquejol. The force fields for the most stable configurations were computed by using those two levels of theory and the complete vibrational assignments for the two conformations of carquejol are reported. The different orientations and directions of the dipole moments of the two structures and the proximity in the nucleophilic indexes with those reported for other terpenes could justify in part the potential biological properties reported for carquejol. The MEP surfaces for both structures reveal that the nucleophilic and electrophilic sites of higher reactivity are principally centred on the OH groups.

Mutation rate of 12 X-STRs from investigator Argus X-12 kit in Argentine population García, M. G.; Gusmão, L.; Catanesi, Cecilia Ines; Penacino, G.A.; Pinto, N. The analysis of X-chromosomal markers can be important in different situations where the application of autosomal and Y- chromosomal STR markers are not sufficient to solve the cases. Currently, the Argentine population lacks a representative database on X-chromosomal markers, regarding allele and/or haplotype frequencies, and mutation rates. The absence of this information represents an important limitation for their routine use in laboratories, preventing the achievement of a quantitative, statistically supported evaluation. In order to estimate mutation rates for the twelve X-chromosomal markers included in the Argus X-12 kit, 345 father-daughter duos were genotyped. The samples were selected from all provinces of Argentina and the biological relationship of paternity was previously confirmed by the analysis of autosomal STR markers for all duos, for which likelihood ratios higher than 106 were achieved. A total of 21 mutations over 4140 allelic transmissions were observed at DXS7132, DXS10134, DXS10079, DXS10146, DXS10101, DXS10103, DXS10074, DXS10148 and DXS10135 loci. The overall X-STRmutation rate observed was 5.1 × 10−3 (95% CI, 3.1 × 10−3–7.7 × 10−3) and all the genotypic configurations were explainable by the gain or loss of a single repeat. Finally, it should be noted that the overall mutation rate observed in this work resulted higher in comparison with some other reports, likely due to only father-daughter duos had been considered. Indeed, these findings are in agreement with previous works suggesting higher mutation rates for males, due to the higher number of germ-line divisions they experience.

Legislador se hace, no se nace: El derrotero de Ramón Gil Navarro en la Confederación argentina; Legislators are made, Not born: the case of Ramón Gil Navarro at the "Argentinian Confederation" Lanteri, Ana Laura En el artículo se analiza el itinerario y la actividad legislativa de Ramón Gil Navarro, tomando como eje la rica trama de redes, recursos, espacialidades, intereses, percepciones y estrategias presentes en su diario personal. Se realizan además algunos cruces con otras fuentes documentales, como sus intervenciones en los debates legislativos y sus crónicas en el periódico oficial El Nacional Argentino. En el primer apartado se presenta una síntesis de su trayectoria privada y pública hasta su elección como diputado, focalizando en sus cualidades, vínculos y atributos de poder. En el segundo, se examina su actividad pública entre 1855 y 1856, en diálogo con ideas vertebrales de la interpretación general de la autora sobre el proceso de conformación político-institucional de la Confederación argentina (1852-1862). En especial, se propone visualizar la manera en que Navarro cimentó y desarrolló su oficio legislativo y restituir la experimentación que supuso el desafío de articularse en dicho proceso.; We analyze Ramón Gil Navarro's itinerary and legislative activity considering the networks, resources, spatialities, interests, perceptions and strategies narrated in his personal diary. We also examine other documentary sources, such as his interventions in the legislative debates and his chronicles in the official newspaper "El Nacional Argentino". In the first section, we synthesize his private and public trajectory until his election as deputy, focusing on his qualities, relationships and attributes of power. In the second, we study his public activity between 1855 and 1856, considering our general interpretation of the political-institutional conformation process of the "Argentine Confederation" (1852-1862). We emphasize his legislative action and the experimentation and challenges of Navarro in that process.

Realismo artístico e imagen cinematográfica: un problema estético de Vertov a Kluge Eugenia Roldán; Artistic Realism and Cinematic Image: an Aesthetic Problem from Vertov to Kluge Galfione, María Verónica; Roldán, Eugenia María El presente trabajo procura reconstruir algunas de las expectativas que se hallaron asociadas al cine en lo que respecta a la posibilidad de una representación fidedigna de la realidad. En este sentido se analizan tanto las primeras teorías cinematográficas del siglo XX como el proyecto vanguardistade Vertov. Posteriormente, se hace una breve mención a algunos de los motivos por los cuales estas expectativas comenzaron a ser puestas en cuestión desde finales de la segunda guerra mundial y fueron definitivamente abandonadas a partir de los años 70. Finalmente, se considera el modo en que un director de cine como Alexander Kluge ha retomado el proyecto realista; This paper aims to reconstruct some of the expectations associated to cinema and its possibility of a true representation of reality. Thus, we start analyzing the first film theories of the twentieth century and Vertov ́s avant-garde project. Then, we make a brief mention of some of the reasons that explain why these expectations began to be called into question since the end of World War II and were definitely abandoned in the 70s. Finally, we consider the way in which the film director Alexander Kluge has resumed the realistic project and has sought to reconfigure it in order to save its validity in the new media context

El traductor como huésped; The Translator as Host Garayalde, Nicolas El siguiente artículo compara dos traducciones al español del ensayo The Critic as Host, del autor norteamericano Joseph Hillis Miller. Se trata de la traducción de Manuel Asensi y María Gimeno (Teoría literaria y deconstrucción, ARCO/LIBROS), por un lado, y la de Susana Guardado y del Castro (Deconstrucción y crítica, Siglo XXI), por otro. Nos enfocaremos específicamente en la traducción del término host que Asensi y Gimeno traducen por anfitrión mientras que Guardado y del Castro por huésped y anfitrión alternativamente. El análisis comparativo nos conducirá a ponderar la hipótesis de que la traducción resignifica el ensayo de Miller, habitándolo parasitariamente (en el sentido que él mismo le da en su escrito a este término), de modo que la traducción de Guardado y del Castro pone en escena una deconstrucción del ensayo y actúa la posibilidad/imposibilidad de la traducción. Trabajaremos esta hipótesis a partir de reflexiones sobre la traducción de Jacques Derrida.; The following paper compares two translations from English to Spanish of the essay “The Critic as Host” by the American author Joseph Hillis Miller: one is the translation made by Manuel Asensi and María Gimeno (T eoría literaria y deconstrucción, ARCO/LIBROS); the other by Susana Guardado y del Castro (Deconstrucción y crítica, Siglo XXI). We will be especially focusing on the translation of the t erm host, which is translated by Asensi and Gimeno as anfitrión, while it is transla- ted by Guardado del Castro alternatively both as huésped and as anfitrión. The comparative analysis will lead us to the following hypothesis: the translation resignifies Miller’s essay in a parasitical way (in the same way that Miller does in his essay), in such a manner that the translation by Guardado y del Castro deploys the deconstruction of the essay and acts out the possibility/impossibility of the translation. We will base our hypothesis on the thinking of Jacques Derrida about translation. Keywords: host, huésped, anfitrión, translation, deconstruction, J.H. Miller.

Revitalización emergente de la ciudad construida: Microdensificación en los barrios pericentrales de Córdoba, Argentina Boccolini, Sara María Se estudió la revitalización por microdensificación que se desarrolla en los barrios pericentrales de Córdoba, en tanto proceso emergente (sin concertación entre los agentes involucrados, ni planificación "tradicional"), que consiste en incorporar nuevas unidades funcionales en parcelas ocupadas originalmente con una vivienda unifamiliar. Este proceso implica una transformación sutil pero definitiva en el tejido espacial, funcional y socioeconómico, así como nuevas lógicas de producción y acceso al hábitat urbano de clases medias. El objetivo fue determinar cuali y cuantitativamente ese impacto, y su potencial para revitalizar áreas urbanas que, aun teniendo gran calidad ambiental y urbana, hoy desarrollan procesos de pauperización del tejido construido y vaciamiento poblacional.Se reconstruyó el proceso emergente a través de las condiciones contextuales que lo catalizan (situación actual de los barrios pericentrales y la producción y consumo de hábitat urbano en Córdoba), y las condiciones que lo estructuran (lógicas de los agentes involucrados, transformaciones espaciales y funcionales del tejido construido, impacto en el mercado de hábitat urbano y en la estructura urbana de la ciudad). Finalmente, se evaluó su impacto en la estructura urbana y se discutió sobre su potencial para revitalizar áreas pericentrales e intermedias de Córdoba y otras ciudades medias de Latinoamérica.

Construcción sociodemográfica en Córdoba (Argentina): cambios de las estructuras sociales en el territorio y su impacto en la demanda de hábitat urbano; Sociodemographic construction in Córdoba (Argentina): changes of social structures in the territory and their impact on the demand for urban habitat Boccolini, Sara María Se reconstruyó la situación de Córdoba, Argentina en cuanto a tendencias sociodemográficas en el territorio en un escenario futuro tendencial a corto plazo. Se combinaron variables demográfico/territoriales de información censal oficial, junto con variables de hábitos de vida y de consumo relevados de informes específicos realizados por consultoras públicas y privadas. Esto se complementó con un análisis sociológico basado en la revisión de bibliografía específica. Se detectaron procesos simultáneos de macrocefalia y contraurbanización, así como cambios en estructuras familiares y estilos de vida característicos de la dialéctica entre transición una condición demográfica avanzada y los procesos propios del neoliberalismo posmoderno actuales.; The situation in Córdoba (Argentina) is revisited in terms of sociodemographic trends in the territory in a future short-term scenario. Demographic/territorial variables from official census data were combined, along with lifestyle and consumption variables surveyed by public and private consultants. This was complemented by a sociological analysis based on a review of the specific literature. Simultaneous macrocephaly and counterurbanization processes were detected, as well as changes in family structures and lifestyles, characteristic of the dialectic between the condition of an advanced demographic transition and processes of the current postmodern neoliberalism.

Acortamiento Paleógeno en el Tramo Medio de los Valles Calchaquíes: Depositación Sintectónica de la Formación Quebrada de los Colorados; Paleogene shortening in the middle sector of the Valles Calchaquíes: syntectonic accumulation of the Quebrada de los Colorados Formation Aramayo, Alejandro José; Hongn, Fernando Daniel; del Papa, Cecilia Eugenia Estudios realizados en diferentes sectores de la Puna y la Cordillera Oriental han confirmado el comienzo de la historia tectono-sedimentaria de la cuenca de antepaís desde el Paleógeno. El tramo medio de los Valles Calchaquíes incluye a los valles de Hualfín, Pucará y Calchaquí (Angastaco-Las Viñas-San Lucas), allí afloran los depósitos del Grupo Salta sobre los que se asienta la sucesión continental del Grupo Payogastilla. La cartografía detallada de rasgos estructurales y sedimentológicos reveló que la unidad basal de este último, de edad eocena (Formación Quebrada de los Colorados), presenta discontinuidades estratigráficas con las rocas infrayacentes y estructuras de crecimiento en sus niveles basales. Estos rasgos demuestran la existencia de un evento de deformación alrededor del Eoceno medio a tardío para este sector de los Andes del norte de Argentina. Esta deformación intracuencal mostró una propagación irregular en espacio y tiempo debido a la reactivación-inversión de las heterogeneidades previas. Las relaciones estratigráficas de la Formación Quebrada de los Colorados y las características de sus facies sedimentarias (rocas clásticas gruesas) permiten interpretar para esta unidad una depositación sintectónica con áreas de aportes locales, promovida por la actividad de las fallas de borde de las distintas zonas de acumulación que levantaron bloques de basamento que limitaron y controlaron la conectividad variable entre ellas. Por todo esto, el tramo medio de los Valles Calchaquíes conforma una zona de decenas de kilómetros donde habría ocurrido el desarrollo de cuencas en un antepaís fragmentado desde el Paleógeno.; Researches performed in several areas of the Puna and the Eastern Cordillera has confirmed the beginning of the tectono-sedimentary history of the foreland basin from the Paleogene. The middle segment of the Valles Calchaquíes region includes the Hualfín, Pucará y Calchaquí (Angastaco-Las Viñas-San Lucas) valleys. Successions of the Salta Group rift basin followed by the continental deposits of the Payogastilla Group foreland basin crop out extensively in these areas. Detailed mapping of structural-sedimentary features revealed that the lowermost unit from the Payogastilla Group of Eocene age (Quebrada de los Colorados Formation) displays stratigraphic unconformities with the underlying rocks and growth structures at its basal levels. These features represent evidences from the existence of a deformation event around the middle to late Eocene at this sector of the Andes from northern Argentina. This intrabasinal deformation showed an irregular propagation pattern in space and time due to the reactivation-inversion of the older heterogeneities. The stratigraphic relationships of the Quebrada de los Colorados Formation and the analysis of its facies (coarse clastic rocks) point to a syntectonic accumulation with local sources supply. Eocene faults bordering the different accumulation areas uplifted basement blocks that limited and controlled the variable connection between the deposition zones. The middle segment of the Valles Calchaquíes preserves the Eocene initial stages of the Payogastilla Group sedimentation. Faults displaced basement blocks from the initial stages of this Eocene broken foreland basin.

Síntesis y caracterización de nanomateriales basados en cobalto: Potenciales aplicaciones en conversión de energía Mayorga, Fabricio; Peláez, Walter José; Menzaque, Alejandro Daniel; Caramellino, Paula; Lamas, Diego Germán; Fuertes, Valeria Cintia El objetivo de este trabajo fue sintetizar la perovskita SrCoO3-d con tamaño nanométrico, a fin de retener la fase metaestable cúbica a temperatura ambiente, un buen candidato para cátodo en SOFCs. Para ello, se utilizó el método de autocombustión, a partir de nitratos precursores, utilizando tres combustibles diferentes (glicina, urea y ácido cítrico con etilenglicol) en distintas relaciones combustible/acomplejante. Tratamientos térmicos posteriores son esenciales para una buena cristalización del producto final. El tamaño de cristalita calculado usando la ecuación de Scherrer está en el intervalo de 50-60 nm. El análisis termogravimétrico mostró la presencia de SrCoO3-d (fase romboédrica) y una banda ancha a ~580 cm-1 en el espectro infrarrojo, pudo atribuirse a la señal característica de perovskitas debida al estiramiento asimétrico Co-O de los octaedros CoO6.Sin embargo, los patrones de difracción de rayos X de polvos mostraron la formación de la fase Sr6Co5O15 y pequeñas cantidades de SrCO3 y Co3O4 como fases secundarias, también corroborado por FT-IR. De estas observaciones se concluye que la perovskita romboédrica SrCoO3-d es, de hecho, una mezcla de Co3O4 con Sr6Co5O15.Aunque la fase cúbica, tecnológicamente interesante, no pudo retenerse a temperatura ambiente, la estabilización de la fase Sr6Co5O15 conduce a nuevos desafíos: sintetizar este material en la nanoescala, con un alto grado de pureza y evaluar sus propiedades como dispositivo termoeléctrico para conversión de energía.; The objective of this work was to synthesize the SrCoO3-d perovskite with nanometric size, in order to retain the metastable cubic phase at room temperature, a good candidate for cathode in SOFCs. For this, the self-combustion method was used, starting from nitrate precursors, and using three different fuels (glycine, urea and citric acid with ethylene glycol) in different fuel / complexing ratios. Subsequent thermal treatments are essential for a good crystallization of the final product. The crystallite size calculated using the Debye-Scherrer equation is in the range of 50-60 nm. Thermogravimetric analysis showed the presence of SrCoO3-? (rhombohedral phase) and a wide band at ~580 cm-1 in the infrared spectrum, could be attributed to the characteristic signal of perovskites due to the Co-O asymmetric stretching of the CoO6 octahedra. However, the X-ray diffraction powder patterns showed Sr6Co5O15 phase and small amounts of SrCO3 and Co3O4 as secondary phases, also corroborated by FT-IR. From these observations we conclude that the rhombohedral perovskite SrCoO3-? is, in fact, a mixture of Co3O4 with Sr6Co5O15. Although the technically interesting cubic phase could not be retained at room temperature, the stabilization of the Sr6Co5O15 phase leads to new challenges: to synthesize this material at the nanoscale with a high degree of purity and to evaluate its properties as a thermoelectric device for energy conversion.

Aplicación de Ánodos basados en Titanatos de Litio para Almacenamiento Electroquímico de Energía: Prototipos de Baterías de Ión-Litio Chauque, Susana; Oliva, Fabiana Yolanda; Camara, Osvaldo Raul En el presente artículo se informan resultados experimentales correspondientes al rendimiento electroquímico de dos materiales activos de titanato de litio (LTO), sintetizados por método cerámico y caracterizados previamente, para ser empleados como electrodo negativo en prototipos de baterías de ión litio (BILs). Estos materiales fueron ciclados galvanostáticamente en forma prolongada empleando litio metálico como electrodo auxiliar, mostrando una excelente reversibilidad en los procesos de carga y descarga durante 300 ciclos. A partir de la proyección de los valores de capacidad específica en función del número de ciclos, se pudo estimar que estos materiales tienen la capacidad de soportar el ciclado galvanostático durante 450-500 ciclos antes de disminuir al 80% de la capacidad inicial. Se ensamblaron dos prototipos de BILs, empleando como electrodo negativo los materiales de LTO y como electrodo positivo un compuesto de fosfato de hierro y litio comercial (LFP). El comportamiento electroquímico de los prototipos estuvo en excelente concordancia con las respuestas de ambos electrodos por separado, medidos en medias celdas con litio metálico como electrodo auxiliar. Se observó que el potencial de celda obtenido en los prototipos es igual a la diferencia de los potenciales de meseta de las celdas LTO/Li y LFP/Li, con un valor de 1,9 V, correspondiente a la inserción/de-inserción de ion litio topotáctica en los dos materiales activos de intercalación. Ambos prototipos mostraron una pérdida de tan solo el 12% de su capacidad específica a lo largo de 300 ciclos de carga/descarga en forma continua, con una muy alta eficiencia de energía observada a través de la constancia en el potencial de carga/descarga y la alta eficiencia coulómbica.; In the present article it is reported experimental results corresponding to the electrochemical performance of two lithium titanate active materials (LTO), synthesized by ceramic method and previously characterized, to be used as a negative electrode in prototypes of lithium ion batteries (BILs). These materials were galvanostatically cycled to long times using metallic lithium as an auxiliary electrode, showing an excellent reversibility in the charging and discharging processes along 300 cycles. From the variation of the specific capacity values as a function of the number of cycles, it was possible to estimate that these materials have the capacity to support the galvanostatic cycling during 450-500 cycles before decreasing to 80% of the initial capacity. Two prototypes of BILs were assembled, using the LTO materials as negative electrode and a commercial lithium iron phosphate (LFP) compound as positive electrode. The electrochemical behavior of the prototypes was in excellent agreement with the responses of both electrodes separately, measured in half cells with metallic lithium as auxiliary electrode. It was observed that the cell potential obtained in the prototypes is equal to the difference of the plateau potentials of the LTO/Li and LFP/Li cells, with a value of 1.9 V, corresponding to the topotactic insertion/deinsertion of lithium ion in the two active intercalation materials. Both BIL prototypes showed a loss in specific capacity of only 12% over 300 charge/discharge cycles, with a very high energy efficiency observed through the constancy in the charge/discharge potential and the high coulombic efficiency.

Atmospheric degradation of 2-chloroethyl vinyl ether, allyl ether and allyl ethyl ether: Kinetics with OH radicals and UV photochemistry Antiñolo, M.; Ocaña, A.J.; Aranguren Abrate, Juan Pablo; Lane, Silvia Irene; Albaladejo, J.; Jiménez, E. Unsaturated ethers are oxygenated volatile organic compounds (OVOCs) emitted by anthropogenic sources. Potential removal processes in the troposphere are initiated by hydroxyl (OH) radicals and photochemistry. In this work, we report for the first time the rate coefficients of the gas-phase reaction with OH radicals (kOH) of 2-chloroethyl vinyl ether (2ClEVE), allyl ether (AE), and allyl ethyl ether (AEE) as a function of temperature in the 263–358 K range, measured by the pulsed laser photolysis–laser induced fluorescence technique. No pressure dependence of kOH was observed in the 50–500 Torr range in He as bath gas, while a slightly negative T-dependence was observed. The temperature dependent expressions for the rate coefficients determined in this work are: kOH,2ClEVE(T)=(9.0±2.0)×10−12exp(478±72T)cm3molecule−1s−1, kOH,AE(T)=(1.3±0.4)×10−11exp(442±91T)cm3molecule−1s−1, kOH,AEE(T)=(5.8±1.3)×10−12exp(563±62T)cm3molecule−1s−1, The estimated atmospheric lifetimes (τOH) assuming kOH at 288 K were 3, 2, and 4 h for 2ClEVE, AE and AEE, respectively. The kinetic results are discussed in terms of the chemical structure of the unsaturated ethers by comparison with similar compounds. We also report ultraviolet (UV) and infrared (IR) absorption cross sections (σλ and σ(ν˜), respectively). We estimate the photolysis rate coefficients in the solar UV actinic region to be less than 10−7 s−1, implying that these compounds are not removed from the atmosphere by this process. In addition, from σ(ν˜) and τOH, the global warming potential of each unsaturated ether was calculated to be almost zero. A discussion on the atmospheric implications of the titled compounds is presented.