Peak characteristics of F2 region over Tucumán: Predictions and measurements Ezquer, Rodolfo Gerardo; Mosert, Marta Estela; Scida, Luis Alberto; López, J. Ionosonde measurements obtained at Tucuman are used to check the validity of the International Reference Ionosphere model to predict the maximum electron density of F2 region (NmF2) and its height (hmF2) over this station. Data corresponding to different months and solar activity conditions are considered. CCIR and URSI options are used to model calculations. The results show that, generally, the predictions of hmF2 are better than those of NmF2. Disagreements between predicted and measured NmF2 values are observed and the consequence in the vertical total electron content modeling are stressed.

A key to the known larvae of south american Elmidae (Coleoptera: Byrrhoidea), with a description of the mature larva of Macrelmis saltensis Manzo. Manzo, María Verónica; Archangelsky, Miguel A key to identify the known mature larvae of the South American genera of the family Elmidae is provided. The key includes seven genera presently assigned to the subfamily Larainae and 15 genera assigned to the subfamily Elminae. New distributional data for all genera and a checklist of described larvae are also included. The mature larva of Macrelmis saltensis Manzo is described and illustrated for the first time, and compared to other known larvae of the granigera species-group. Distributional notes for M. saltensis increase its known range to the north, this being the first citation of the species for Bolivia. Macrelmis isis (Hinton) is also cited for the first time for Bolivia.

Insecticidal activity of the essential oil and extracts of Gutierrezia mandonii and G. repens (Asteraceae) growning in Argentina Clemente, Sandra Viviana; Mareggiani, Graciela Silvia; Juarez, Berta Estela; Mendiondo, Maria Elena; Van Baren, Catalina Maria; Di Leo Lira, Paola Maria del Rosario; Broussalis, Adriana Maria; Bandoni, Arnaldo Luis; Ferraro, Graciela Ester The insecticidal activities of essential oils (EO), the remaining water phase (RW) from the hydrodistillation, and the dichloromethane and methanolic extracts from Gutierrezia repens Griseb. and Gutierrezia mandonii (Sch. Bip.) Solbrig were evaluated. The GC and GC/MS analyses of the oils resulted in the identification of 52 compounds from G. mandonii and 17 compounds from G. repens comprising 88.7% and 98.5% of the oils, respectively. Sabi- nene (0–13.1%), β-pinene (6.4–17.8%) limonene (0.7–13.3%), (E)-β-ocimene (1.3–7.0%), terpinen-4-ol (0.7–4.1%), spathulenol (0–4.1%) and, the isomers (6R,7R)-bisabolone (6.6–58.0%) and (6S,7R)-bisabolone (0–1.6%) were the main components of the oils. Mortality and development delays of Ceratitis capitata larvae, reared using a treated artificial diet, were recorded. Gutierrezia mandonii methanolic extracts and the oil produced lethal effects (p≤0.05). Methanolic and dichloromethane extracts, the oil and the remaining water from distillation (RW) produced sublethal effects. Meanwhile dichloromethane and methanolic extracts, the oil and RW from G. repens resulted in significant mortality (p≤0.05), and all causing also significant development delays. The required concentration of G. repens oil to avoid development in 50% of C. capitata larvae (EC50) was significantly lower than G. mandonii

La minoridad como elemento de sostén institucional y político Noceti, Maria Belen Con motivo de cumplirse 100 años de la fundación de la Institución denominada Patronato de la Infancia en la ciudad de Bahía Blanca, provincia de Buenos Aires, Argentina; desde la Universidad Nacional del Sur se realizó una investigación a fin de caracterizar un siglo de prácticas institucionales en torno a la protección de la niñez en la ciudad. En este recorrido se delimitaron distintos modelos institucionales que se sucedieron e incluso convivieron en el ámbito de dicha institución. Esta presentación muestra los resultados alcanzados en dicha intervención que combinó una investigación histórico-documental con una aproximación etnográfica respecto de las prácticas que configuran el campo de la niñez en riesgo. Los resultados aportan elementos de diagnóstico respecto de la construcción del concepto de niñez, de familia y de estado en un ámbito que resulta emblemático para la identidad bahiense y con fuerte contenido positivista, propio del paradigma jurídico de situación irregular.; On the occasion of its 100th year of the founding of the institution called the Board of Trustees for Children in the city of Bahia Blanca, province of Buenos Aires, Argentina, from the Universidad Nacional del Sur was conducted an investigation to characterize a century of institutional practices on the protection of children in the city. In this route were identified various institutional models that are succeeding and even lived in the area of the institution. This presentation shows the results achieved in that speech that combined historical research with an ethnographic documentary regarding the practices that shape the field of children at risk. The results provide diagnostic elements on the construction of the concept of childhood, family and state in an area that is emblematic for the identity and bahiense with strong positivist, legal paradigm itself irregular.

El humor o la fatalidad de la hermenéutica López Corral, Francisco El artículo pretende aportar algunos elementos en vistas a una indagación acerca de los límites de la aventura hermenéutica. A tal fin, se propone un recorrido con la intención de reconstruir la intuición que guía a la hermenéutica en su pretensión de convertirse en horizonte de toda experiencia posible (tal como se propone en el proyecto gadameriano). A continuación, se realiza un examen de la experiencia humorística, a partir del cual se desanda el camino hermenéutico para explorar la relación paradójica entre sentido y sinsentido que atraviesa el humor. Finalmente, esta contraposición entre la experiencia hermenéutica y la humorística, es planteada como línea de ensayo para una problematización sobre las posibilidades y los límites de la propia filosofía.

Envejecimiento y diferenciación socio-espacial: Calidad de vida de los adultos mayores en Bahía Blanca Formiga, Nidia Ester; Prieto, Maria Belen El envejecimiento de la población es uno de los fenómenos de mayor impacto de este siglo y es uno de los temas prioritarios en las agendas de los organismos internacionales y nacionales, decidores públicos y privados y organizaciones de la sociedad civil.

Galicia, el correo marítimo y el transporte de caudales hacia España: Una reversión geopolítica y económica para el cono sur de América Silva, Hernan Asdrubal Este trabajo se dirige a estudiar el significado que tuvo, para el Río de la Plata en particular y la navegación atlántica en general, la apertura de la ruta del Correo Marítimo Hispanoamericano entre La Coruña y Montevideo, rompiendo con el monopolio gaditano. Situación que se enriquece con el análisis de los vínculos tierra-mar, encauzados a través de las diversas carreras establecidas y del análisis del flujo de metálico, particularmente el oro.; This work seeks to study the meaning that had, for the Río de Ia Plata particularly and for the Atlantic sailing in general, the Opening of the route of the HispanicAmerican sailing mail between The Coruña and Montevideo, in that way broking with the monopoly of Cádiz. Situation that is enriched with the analysis of the land-sea ties channeled through the several established toutes, and the analysis of the metallic flow, particularly that of gold.

Movilidad de los metales y otros elementos en el acuífero Loéssico regional del suroeste bonaerense Bonorino, Alfredo Guillermo; Limbozzi, Fabiana; Albouy, Edgardo René; Lexow, Claudio Se analizaron las concentraciones de elementos mayoritarios, menores y traza en el agua subterránea del acuífero freático regional de la vertiente occidental de las Sierras Australes, contrastándolas con la composición química del loess y del vidrio volcánico loéssico. Se calculó además el grado de movilidad relativa (MR) de cada elemento en el agua subterránea. A excepción de U y As, todos los elementos analizados exhiben baja movilidad. El amplio espectro de movilidad denota que la meteorización del loess es un proceso incongruente. Zr, Al, Th y Ti son los elementos con la movilidad más baja. Los elementos que forman oxohidroxoaniones, en particular U y As, tienen altos valores de MR. La movilidad de la secuencia de los elementos alcalinos y alcalinos térreos posee un patrón análogo al orden de la afinidad de sorción con los minerales de arcilla, teniendo el Cs y el Rb los MR más bajos y el Sr, Ca y Mg los MR más altos. Los metales de la transición muestran valores intermedios de MR, entre los alcalinos-alcalinos térreos y los elementos inmóviles. Las movilidades relativas del Fe, Co y Mn son las más bajas de este grupo. El Cr, Cd y Ni tienen valores moderados mientras que debido a las condiciones oxidantes del sistema acuífero, elementos como U, Mo, Zn, As y V exhiben gran movilidad. La formación de complejos con carbonatos influencia la geoquímica de la solución del U, del As y del Sn. La fuente principal de metales incorporados al flujo subterráneo sería el vidrio volcánico loéssico. Además de As se presentan otros elementos que alteran la calidad del agua subterránea con riesgo para la salud.; The major, minor and trace metals concentrations were analyzed from twelve groundwater samples of the western slope of the Australes ranges, contrasting them with loess chemical composition and loessic volcanic glass. Also, the relative mobility of each metal in the groundwater was calculated. The main source of metals in groundwater is loessic volcanic glass; the process of weathering of loess is incongruent. Oxidizing conditions of the aquifer system enhance the mobility of some metals like As, U, V and Zn and decrease the mobility of other like Mn and Co. In addition to As several toxic metals wich modify groundwater quality promoting risk to human health are showed.

Notas sobre la vida y obra del Dr. Egidio Feruglio; Notes on the life and work of Dr. Egidio Feruglio Spalletti, Luis Antonio Egidio Feruglio nació el 1 de septiembre de 1897, en Feletto Umberto, comuna de Tavagnacco, provincia de Udine, Italia. Después de la finalización de la Primera Guerra Mundial de la que participó como oficial, y a la edad de 22 años, completó sus estudios universitarios en la Universidad de Florencia. En sus primeros tiempos como profesional se desempeñó como geólogo en la Oficina Hidrográfica y en el Departamento Agrario de Udine, y entre 1922 y 1925 ocupó el cargo de auxiliar docente de la Cátedra de Geología de la Universidad de Cagliari. Egidio Feruglio no era un político, pero tenía fuertes convicciones antifascistas. Como consecuencia de la suspensión de las actividades de los partidos políticos y el aniquilamiento de la oposición democrática por parte de Benito Mussolini, decidió emigrar a la República Argentina en 1925, incorporándose como geólogo de la entonces Dirección de Yacimientos Petrolíferos Fiscales donde inicia sus trabajos profesionales y de investigación en la región patagónica. En 1928 regresa a Italia y contrae matrimonio con la señorita Amelia Magrini. De esta unión nacerán dos hijos Anna Eugenia y Arturo. En 1929 se instala nuevamente en YPF donde ocupa las funciones de Jefe de Comisión y luego Jefe del Grupo Geológico del Golfo San Jorge hasta el 1932, año en que acepta el cargo de profesor en la Universidad de Bologna. No obstante, en 1934, retorna a nuestro país para retomar su actividad profesional en la empresa petrolera estatal. En 1940 acepta la designación de profesor en la Escuela de Agronomía de la Universidad de Cuyo, y en 1943 organiza y dirige el Instituto del Petróleo. Permanece en Mendoza hasta 1948. Terminada la Segunda Guerra Mundial e instaurada la república italiana, regresa definitivamente a su país donde ejerce las funciones de profesor en las universidades de Turín y de Roma. A principios de 1954 vuelve a Udine donde fallece el 14 de julio, a la edad de 56 años. Los trabajos publicados sobre la República Argentina por el Dr. Egidio Feruglio, abarcan desde 1926 hasta 1957 (tres años después de su muerte). Sus estudios comprenden contribuciones geológicas regionales y estratigráficas, paleontológicas, geomorfológicas y de la geología del Cuaternario, así como geográficas referidas a la orografía y glaciología del territorio argentino. Desde el punto de vista regional, sus más importantes aportes están referidos a la Patagonia continental, tanto extraandina como andina. Su obra más trascendente fue la Descripción Geológica de la Patagonia, elaborada en la década del 40, cuando el autor se desempeñaba como docente e investigador en la Universidad Nacional de Cuyo. El excepcional trabajo fue publicado por la Dirección General de Yacimientos Petrolíferos Fiscales en tres tomos, entre los años 1949 y 1950, y puede considerarse uno de los aportes más trascendentes al conocimiento geológico de nuestro país publicados por un único autor. El texto es de un rigor científico extraordinario, constituye una obra metódica en la que se brindan extensas y detalladas descripciones geológicas, paleontológicas, geomorfológicas y geográficas, y se efectúan valiosas y bien fundadas interpretaciones. La obra sintetiza toda la información obtenida por el Dr. Feruglio en largas y minuciosas tareas de campaña, pero sin excluir muy completas referencias a los trabajos realizados por investigadores que lo precedieron y que fueron sus contemporáneos. El Dr. Egidio Feruglio fue sin dudas uno de los geólogos más prominentes de nuestro país. Desde muy temprana edad sintió profundo amor por las ciencias de la Tierra. Supo entregarse a la investigación básica geología, paleontología y geomorfología, así como a la actividad profesional, especialmente en el área de la prospección de hidrocarburos. Su obra refleja un notable empeño por su trabajo, minuciosidad y creatividad. Su vida fue un ejemplo de dignidad civil y social.; Egidio Feruglio was born on 1 September 1897 at the family home of Feletto Umberto, Tavagnacco county, Udine, Italy. From his teenage years, Egidio Feruglio had held a keen interest in geology and geomorphology, becoming involved in the Udine´s Speleological Society. After the end of the World War I, in which he served as an officer of the Italian Army, and at the age of twenty two years old, he earned his geologist degree in the University of Florence. While at Udine, he worked as a geologist in the Hydrographic and Agricultural Departments. Between 1922 and 1925 he served as assistant professor in the University of Cagliari. Egidio Feruglio was not a politician, but he had strong democratic principles. When Benito Mussolini suspended de political activities and removed politically suspect employees (including university professors) from their jobs unless they had demonstrated loyalty to fascism, Feruglio decided to accept a position in the Dirección de Yacimientos Petrolíferos Fiscales (the National Oil Copany) of Argentina. Between 1925 and 1928 he worked as a regional geologist in southern Argentina (Patagonia). In 1928 he returned to Italy and married Amelia Magrini, with whom he would have two children, Ana Eugenia and Arturo. In 1929 he went back to Argentina to lead the Geologic Group of the San Jorge Gulf Basin in Yacimientos Petrolíferos Fiscales (YPF). In 1932 he relocated again in Italy as a professor in the University of Bologna, but in 1934 he decided to return to YPF until 1940, when he accepted a professor position in the University of Cuyo (Mendoza), where he organized the Petroleum Institute (1943). After the end of the World War II and the creation of the Italian Republic the Feruglios decided to move back to Italy. Since 1948 Egidio became professor of Geology of the University of Turin, but the death of his young son Arturo profoundly grieved him. He decided then to move to the University of Rome. However, early in 1954 he settled back in his natal place where he died on 14 July at the age of fifty six years old. From 1926 to 1957 (three years after his death) Feruglio published a large number of contributions on regional geology, stratigraphy, paleontology, geomorphology and Quaternary geology of Argentina, as well as several papers on its orography and glaciology. The main focus of his regional research was the south of Argentina and his monumental work entitled Descripción Geológica de la Patagonia resumes years of field work and data collection. This book was published by YPF in three volumes, between 1949 and 1950. It constitutes a detailed synthesis of the geology, paleontology, geomorphology and geography of the southern territories of Argentina. Far from a merely description, Ferugio realized valuable and well supported interpretations that demonstrated that he had a clear view of the problems of geology and the determination to solve them. Egidio Feruglio was one of the most prominent geologists of Argentina. For early on he discovered his love for Earth Sciences. He enjoyed geology as a whole, since he was able to combine basic research with valuable works on hydrocarbon exploration and exploitation.

New ages and chemical analysis on Lower Jurassic volcanism close to the dorsal de Huincul, Neuquén; Nuevas edades del volcanismo Jurásico Inferior de la cuenca Neuquina en la dorsal de Huincul Schiuma, Mario; Llambias, Eduardo Jorge New single zircon ages from hydrocarbon well cores in the A-1 Norte de la Dorsal and Anticlinal Campamento area of the Neuquén basin indicate that 199.0 ± 1.5 Ma andesite lava flow and 203.75 ± 0.26 Ma dacite breccia overlie a 286.5 ± 2.3 Ma granodiorite and 284.0 ± 1.3 Ma andesite dike. The Lower Jurassic volcanics were deposited on a regional erosion surface affecting the Permian rocks. In the studied area there is no record of Middle to Upper Triassic volcanics as in other areas of the basin. Exotic zircon crystals gave ages of Mesoproterozoic, Middle Cambian, Early Devonian and Early Carboniferous, suggesting a poliphasic basement. Chemical analyses of three selected samples show a calc-alkaline signature, supporting the existence of a volcanic arc at the Early Jurassic as it has been proposed for the center of the basin.; Se dan nuevas edades U/Pb en cristales únicos de circón de muestras de corona de pozos exploratorios en el área petrolera A-1 Norte de la Dorsal y Anticlinal Campamento de la cuenca Neuquina. Estas edades permiten acotar un volcanismo Jurásico Inferior apoyado directamente sobre un basamento ígneo del Pérmico Inferior. Una muestra de andesita arrojó una edad de 199,0 ± 1,5 Ma y una de dacita 203,75 ± 0,26 Ma. El basamento está constituido por una granodiorita de 286,5 ± 2,3 Ma intruida por diques de andesita con 284,0 ± 1,3 Ma, ambas rocas están cortadas por una superficie de erosión de carácter regional labrada durante el Triásico, posiblemente Medio. En las perforaciones estudiadas no se han encontrado rocas triásicas. Los circones exóticos hallados indican la existencia de un complejo basamento con edades del Mesoproterozoico, Cámbrico Medio, Devónico Temprano y Carbonífero Temprano. Los análisis químicos muestras una filiación calco-alcalina que apoya la hipótesis de la existencia de un arco volcánico Jurásico Temprano en el centro de la cuenca Neuquina

Nitrosation of N-methylhydroxylamine by nitroprusside: a kinetic and mechanistic study Gutierrez, Maria Marta; Alluisetti, Graciela Beatriz; Olabe Iparraguirre, Jose Antonio; Amorebieta, Valentín Tomás The kinetics of the reaction between aqueous solutions of Na 2[Fe(CN)5NO]•2H2O (sodium pentacyanonitrosylferrate(ii), nitroprusside, SNP) and MeN(H)OH (N-methylhydroxylamine, MeHA) has been studied by means of UV-vis spectroscopy, using complementary solution techniques: FTIR/ATR, EPR, mass spectrometry and isotopic labeling (15NO), in the pH range 7.1-9.3, I = 1 M (NaCl). The main products were N-methyl-N-nitrosohydroxylamine (MeN(NO)OH) and [Fe(CN)5H2O]3-, characterized as the [Fe(CN)5(pyCONH2)]3- complex (pyCONH 2 = isonicotinamide). No reaction occurred with Me2NOH (N,N-dimethylhydroxylamine, Me2HA) as nucleophile. The rate law was: R = kexp [Fe(CN)5NO2-] × [MeN(H)OH] × [OH-], with kexp = 1.6 ± 0.2 × 105 M-2 s-1, at 25.0 °C, and ΔH # = 34 ± 3 kJ mol-1, ΔS# = -32 ± 11 J K-1 mol-1, at pH 8.0. The proposed mechanism involves the formation of a precursor associative complex between SNP and MeHA, followed by an OH--assisted reversible formation of a deprotonated adduct, [Fe(CN)5(N(O)NMeOH)]3-, and rapid dissociation of MeN(NO)OH. In excess SNP, the precursor complex reacts through a competitive one-electron-transfer path, forming the [Fe(CN)5NO]3- ion with slow production of small quantities of N2O. The stoichiometry and mechanism of the main adduct-formation path are similar to those previously reported for hydroxylamine (HA) and related nucleophiles. The nitrosated product, MeN(NO)OH, decomposes thermally at physiological temperatures, slowly yielding NO.

The coordination chemistry of nitrosyl in cyanoferrates: an exhibit of bioinorganic relevant reactions Olabe Iparraguirre, Jose Antonio Sodium nitroprusside (SNP, Na 2 [Fe(CN) 5 (NO)] •2H 2 O) is a widely used NO-donor hypotensive agent, containing the formally described nitrosonium (NO + ) ligand, which may be redox-interconverted to the corresponding one-electron (NO) and two-electron (NO - /HNO) reduced bound species. Thus, the chemistry of the three nitrosyl ligands may be explored with adequate, biologically relevant substrates. The nitrosonium complex, [Fe(CN) 5 (NO)] 2- , is formed through a reductive nitrosylation reaction of [Fe III (CN) 5 (H 2 O)] 2- with NO, or, alternatively, through the coordination of NO 2 - to [Fe II (CN) 5 (H 2 O)] 3- and further proton-assisted dehydration. It is extremely inert toward NO + -dissociation, and behaves as an electrophile toward different bases: OH - , amines, thiolates, etc. Also, SNP releases NO upon UV-vis photo-activation, with formation of [Fe III (CN) 5 (H 2 O)] 2- . The more electron rich [Fe(CN) 5 (NO)] 3- may be prepared from [Fe II (CN) 5 (H 2 O)] 3- and NO, and is also highly inert toward the dissociation of NO (k = 1.6 × 10 -5 s -1 , 25.0 °C, pH 10.2). It reacts with O 2 leading to SNP, with the intermediacy of a peroxynitrite adduct. The [Fe(CN) 5 (NO)] 3- ion is labile toward the release of trans-cyanide, forming the [Fe(CN) 4 (NO)] 2- ion. Both complexes exist in a pH-dependent equilibrium, and decompose thermally in the hours time scale, releasing cyanides and NO. The latter may further bind to [Fe(CN) 4 (NO)] 2- with formation of a singlet dinitrosyl species, [Fe(CN) 4 (NO) 2 ] 2- , which in turn is unstable toward disproportionation into SNP and N 2 O, and toward the parallel formation of a tetrahedral paramagnetic dinitrosyl compound, [Fe(CN) 2 (NO) 2 ]. Emerging studies with the putative nitroxyl complex, [Fe(CN) 5 (HNO)] 3- , should allow for a complete picture of the three nitrosyl ligands in the same pentacyano fragment. The present Perspective, based on an adequate characterization of structural and spectroscopic properties, will focus on the kinetic and mechanistic description of the above mentioned reactions, which display a versatile scenario, fundamentally related to the biologically relevant processes associated with NO reactivity.

La escritura de la historia en Ecuador tiene cuerpo de mujer: A propósito de Baldomera de Alfredo Pareja Diezcanseco Nofal, Silvia Rossana El lenguaje despojado del realismo le sirve al autor, un sobreviviente al igual que su personaje, para pensar una representación de los hechos cuando los gusanos hayan destruído la materialidad de los cuerpos y sus testimonios." En Baldomera, los referentes locales adquieren universalidad en las cuestiones de género: la historia de esta heroína fracasada puede ser leída como la del país, inscrita en el cuerpo de una mujer pobre, fea y negra, que termina sus días en una cárcel. Aunque es fuerte y resiste (sobrevive sin armas la matanza de noviembre de 1922), en los enfrentamientos con la ley -con la violencia racional de sus armas-, ella pierde, esto agrega un elemento más a las tensiones entre la pequeñez y lo grande, presentes en toda la novela. Un poco como el mismo autor, sobreviviente del Grupo de Guayaquil, cuando testifica sobre el trabajo literario de los Cinco como un Puño, intelectuales modernos con voz crítica ante las realidades sociales y las contradicciones de los años treinta.; The language stripped from realism serves the author, a survivor just like his character, to think of a representation of the facts when the worms have destroyed the substance of bodies and testimony." In Baldomera, local references gain universality in regards to genre: the story of this failed heroine can be seen as that of the nation, written into the body of a poor woman, black and ugly, who finishes out her last days in jail. Though she is strong and fights (she survives the November 1922 massacre without being armed), in her encounters with the law-with the rational violence of her weapons-, she loses, this adds another element to the tensions between the small and the large, that are present throughout the novel. A bit like the author himself, survivor of the Guayaquil Group, who testifies for the literary work of the los Cinco como un Puño (Five Like a Fist), modern intellectuals with a critical voice when 1acing the contradictions and social reality 01 the 1930's.

Tensile Properties, Barrier Properties, and Biodegradation in Soil of Compression—Molded Gelatin-Dialdehyde Starch Films Martucci, Josefa Fabiana; Ruseckaite, Roxana Alejandra Glycerol (Gly)‐plasticized gelatin (Ge) films crosslinked with dialdehyde starch (DAS) as environmentally friendly crosslinking agent were successfully produced by compression molding, demonstrating the capacity of gelatin of being transformed into films by using thermoplastic processes. The effect of DAS content on the color, light transmission, total soluble matter (TSM), water uptake (WU), water vapor permeability (WVP), oxygen permeability (OP) as well as biodegradability during soil burial was investigated. The addition of up to 10 wt % DAS (Ge‐10DAS) generated transparent films, with reduced TMS, WU, WVP, and OP values but higher extensivity than the uncrosslinked counterpart. Further incorporating DAS into plasticized‐gelatin matrix conducted to phase separation with detrimental effect of transparency and tensile properties. DAS‐containing films degraded at slow rate than the uncrosslinked counterpart, suggesting that biotic attack during soil burial is restricted by covalent crosslinking points induced by DAS. Ge‐10DAS films lost about 28% of their initial mass within the first 8 days of exposure to degrading medium; therefore, the material can be classified as rapidly degradable.

Kinetic and stability studies of Ru/La2O3 used in the dry reforming of methane Carrara, Carlos Roberto; Múnera Agudelo, John Fernando; Lombardo, Eduardo Agustin; Cornaglia, Laura Maria The catalytic activity toward hydrogen production through the dry reforming of methane was determined for Ru supported on lanthanum oxide. The catalyst remained stable for more than 80 h in the 823-903 K temperature range and reactant partial pressure ratio (PCO2/PCH 4) equal to unity. However, a significant deactivation was observed during the kinetic measurements when the catalyst was exposed to P CO2/PCH4 > 1 at 823 K. In order to establish why the catalyst deactivated, the Ru reactivity in reductive and CO2 rich atmospheres was studied by in situ LRS and XPS spectroscopies. The partial re-oxidation of metallic Ru could be one of the factors that produce the catalyst deactivation. To perform the kinetic measurements, the temperature range and the partial pressure ratios were selected within the window where the Ru catalyst was stable. The kinetic data and supporting spectroscopic evidence is consistent with a mechanism in which the metal and the oxide play key roles in decomposing the paraffin and activating the CO2, respectively.

Study of a multitubular fixed-bed reactor for ethylene production via ethane oxidative dehydrogenation Lopez, Eduardo; Heracleous, Eleni; Lemonidou, Angeliki A.; Borio, Daniel Oscar In the present contribution, a theoretical study of a multitubular fixed bed reactor for the ethane to ethylene oxidative dehydrogenation reaction over a highly active and selective Ni-Nb-O mixed oxide catalyst is presented. Two reactor designs are proposed and their performance is analyzed by means of a mathematical model of the catalytic bed. The results suggest that the reactor operation would be feasible, provided that high heat transfer area per unit volume and low oxygen concentrations along the tube are maintained. A two-bed multitubular reactor with intermediate air injection proved to be superior to a single-bed design. In fact, the two-bed configuration offers higher ethylene production rates, due to the increased ethylene selectivity while operation under lower oxygen partial pressures. © 2008 Elsevier B.V. All rights reserved.

Rigorous formulation for electromagnetic planewave scattering from a generalüshaped groove in a perfectly conducting plane: Comment Skigin, Diana Carina; Depine, Ricardo Angel We show that the problem of scattering of an obliquely incident plane wave by a generalüshaped groove engraved on a perfectly conducting plane, which was recently studied by Basha et al. [J. Opt. Soc. Am. A 24, 1647 (2007)], was solved 11 years ago using the same formulation. This method was further extended to deal with a finite number of grooves and also with complex apertures including several nonlossy and lossy dielectrics, as well as real metals. © 2008 Optical Society of America.

Caffeoyl esters of threonic acid and its lactone from Viguiera Pazensis Uriburu Monasterio, Maria Laura; Gil, Roberto L.; Sosa, Virginia Estela; de la Fuente, Juana Rosa Dos ésteres de derivados de azúcares con ácido cafeico: 3-O-cafeoil-2-C-metil-D-treono-1,4-lactona, ácido 4-O-cafeoil-2-C-metil-D-treónico, junto con los compuestos previamente conocidos: 2-C-metil-D-treono-1,4-lactona, ácido cafeico, carabrona, 5,7,3'-trihidroxi-4'-metoxiflavona y 5,7,3'-trihidroxi-6,4'-dimetoxiflavona fueron aislados de la parte aérea de Viguiera pazensis. Las estructuras fueron determinadas utilizando una combinación de métodos espectroscópicos, incluyendo espectroscopia de RMN en una y dos dimensiones.; Two caffeoyl esters of sugar derivatives: 3-O-caffeoyl-2-C-methyl-D-threono-1,4-lactone, 4-O-caffeoyl-2-C-methyl-D-threonic acid, along with the previously known compounds: 2-C-methyl-D-threono-1,4-lactone, caffeic acid, carabrone, 5,7,3'-trihydroxy-4'-methoxyflavone, and 5,7,3'-trihydroxy-6,4'-dimethoxyflavone were isolated from the aerial parts of Viguiera pazensis. Their structures were elucidated by application of various spectroscopic methods, including 1D and 2D NMR spectroscopy.

Un futuro frente al río. Gestos de interpretación en el discurso de lo urbano Millán, María del Rosario En este trabajo analizo un proyecto de planificación urbana aprobado por el Concejo Deliberante de la Ciudad de Posadas, Misiones, Argentina. Concentro mi atención en relevar ciertos efectos de sentido y gestos de interpretación derivados de este texto en particular. Considero que este tipo de documentos puede ser analizado en tanto materialización del "discurso de lo urbano" entendido como el discurso referido a la organización urbana, que tiene un alcance performativo sobre la figuración física y simbólica de la ciudad, ya que constituye uno de los principales discursos que sustentan y legitiman los actuales procesos de transformación urbana que experimenta la ciudad.; In this paper I analyze a city-planning project approved by the local council of Posadas Misiones, Argentina. My interest is focus on certain effects of sense and gestures of interpretation derived from that particular text. I consider that this type of documents are materializations of what is called “urban discourse”, understood as the speech about urban organization, which has performative effects on the physical and symbolic figuration of the city, because it constitutes one of the main discourses that sustain and legitimize the present processes of urban transformation that experiences the city.

The advertisement call of Argenteohyla siemersi pederseni (Amphibia, Anura, Hylidae) and comments on its taxonomic status Zaracho, Victor Hugo; Areta, Juan Ignacio Argenteohyla siemersi, nominate A. s. siemersi and A. s. pederseni, are currently recognized. It was suggested that analysis of nuptial calls and chromosome structure would contribute to clarify their taxonomic status. In this paper we describe the advertisement call of Argenteohyla siemersi pederseni from Reserva Natural Provincial Iberá, Corrientes, Argentina, and comment on its taxonomic status. The advertisement call of A. s. pederseni is quite variable in duration and number of notes. Additionally it seems to perform synchronized duets. The call of A. s. pederseni is similar to that of A. s. siemersi in note structure and duration, but the fundamental frequency and the number of notes for call were higher in A. s. pederseni than in A. s. siemersi. These data suggest that siemersi and pederseni could belong to different biological species, although further work is needed to support this assertion; Actualmente se reconocen dos subespecies de Argenteohyla siemersi, la nominal A. s. siemersi y A. s. pederseni. Se ha sugerido que estudios cromosómicos y bioacusticos podrfan ayudar a clarificar su estado taxon6mico. En este trabajo describimos por primera vez el canto de advertencia de Argenteohyla sieniersi pederseni sobre la base de una poblaci6n procedente de la Reserva Natural Provincial Ibera, cerca de la localidad de Colonia Carlos Pellegrini, Corrientes, Argentina. El canto de A. s. pederseni es muy variable en duraci6n y numero de notas. Ademas, parecen vocalizar en duos sincronizados evitando la superposici6n de notas. En comparaci6n con la subespecie nominal, existen diferencias con respecto a la frecuencia fundainental y al número de notas por canto, siendo mayor en A. s. pederseni queen A. s. siemersi. Estos datos sugieren que siemersi y pederseni podrfan corresponder a dos especies biol6gicas distintas, pero más trabajo es necesario para corroborar esta propuesta