The Einstein Nanocrystal Bertoldi, Dalía Surena; Fernandez Guillermet, Armando Jorge; Miranda, Enrique Nestor We study the simplest possible model of nanocrystal consisting in a simple cubic lattice with a small number of atoms (NA ~ 10-10^3), where each atom is linked to its nearest neighbor by a quantum harmonic potential. Some properties (entropy, temperature, specific heat) of the nanocrystal are calculated numerically but exactly within the framework of the microcanonical ensemble. We find that the presence of a surface in the nanocrystal modifies the thermostatistic properties to a greater extent than the small number of atoms in the system. The specific heat Cv behaves similarly to the Einstein solid, with an asymptotic value for high temperatures that differs from that of the Dulong-Petit law by a term of the order of NA^(-1/3) and that can be explained easily in terms of the surface. The entropy is non-additive, but this is due to the presence of the surface and we show that the additivity is recovered in the thermodynamic limit. Finally, we find that, when calculations follow the canonical ensemble, results differ little for small systems (NA = 27) and are inexistent for larger systems (NA = 1000).

Inserción desigual de inmigrantes bolivianos en un mercado de trabajo segmentado : un estudio en municipios del este salteño; Unequal insertion of bolivian immigrants in a segmented labor market : a study in municipalities in eastern salta Ataide, Soraya En este trabajo nos proponemos aportar a los estudios sobre migración y movilidad social, analizando las trayectorias y redes migratorias de bolivianos vinculados a un mercado de trabajo agrícola. Nuestro objetivo entonces es explicar la conformación de un mercado de trabajo segmentado por la etnia nacionalidad boliviana. Partimos de la necesidad de discutir la idea de “colectividad boliviana” como un grupo homogéneo y de relativizar el éxito socio económico de ciertos inmigrantes laborales. También destacamos la importancia de observar las trayectorias y redes migratorias que conforman, atravesadas por distintas desigualdades y ancladas en diferentes contextos espacio - temporales. Nuestro referente empírico se ubica en dos municipios del este salteño, Apolinario Saravia y Gral. Pizarro, donde actualmente se desarrolla una producción hortícola de frescos, orientada al mercado interno, con una fuerte presencia de trabajadores y productores de origen boliviano, que fueron llegando, desde hace por lo menos cinco décadas, en distintos contextos espacio – temporales, nacional, regional provincial y local. Utilizamos una estrategia metodológica de tipo longitudinal cualitativa y nuestra herramienta metodológica es la trayectoria migratoria, a la vez que la utilizamos como unidad de análisis.; The aim of this paper is to contribute to studies on migration and social mobility by analysing the migratory tracks of Bolivian migrants in a horticultural labor market. Our purpose is to explain the formation of a labor market segmented by the Bolivian nationality and ethnicity. Our starting point is the need to discuss the idea of the “Bolivian community” as a homogeneous group and to relativize the socio-economic success of a small group of these immigrants. We also emphasize the importance of observing their migratory tracks and networks, crossed by different inequalities and anchored in different spatio - temporal contexts. Two municipalities of eastern Salta, Apolinario Saravia and Gral. Pizarro, constitute our empirical references. There, a horticultural production of fresh produce is being developed, oriented to the domestic market, with a strong presence of workers and producers of Bolivian origin for at least five decades in different spatio - temporal, national, regional and local contexts. We use a longitudinal qualitative methodological strategy and our methodological device and also unit of analysis is the “migratory track”.

Synergetic interplay between metal (Pt) and nonmetal (C) species in codoped TiO2: A DFT+U study Morgade, Cecilia Ines Nora; Cabeza, Gabriela Fernanda The structural, energetic, magnetic and electronic properties of Pt-C-doped and Pt/C-codoped TiO2 have been studied using first-principle calculations to elucidate the effect of the metal-nonmetal interactions. Compared with other non-metals, C-doping induces the formation of complex structures on titania. From the analysis of the electronic structures of the C-doping system, band gap narrowing as well as the formation of localized gap states are observed in it. The calculated results are in agreement with the experimental absorptions observed in the UV-visible diffuse reflectance spectroscopy spectra. Based on our results, the main findings relating to Pt/C codoping are the formation of highly symmetric coordination-like compounds and the formation of impurity states in the band gap that could be propitious for the separation of photoexcited electron-hole pairs. Is especially remarkable the case of Pt/C@Ti-codoped TiO2 which could be the most effective for the redox reaction of H2O to produce H2 and O2 because it presents the greatest narrowing of the band gap, the lower shift of the conduction band and it is the only one that favorably modifies the position of valence band. All are necessary conditions for the reaction mentioned.

New national and regional bryophyte records, 46 Ellis, L.T.; Asthana, A.K.; Srivastava, P.; Omar, I.; Rawat, K.K.; Sahu, V.; Cano, M.J.; Costa, D.P.; Dias, E.M.; Dias dos Santos, N.; Silva, J.B.; Fedosov, V.E.; Kozhin, M.N.; Ignatova, E.A.; Germano, S.R.; Golovina, E.O.; Gremmen, N.J.M.; Ion, R.; Ştefǎnuţ, S.; von Konrat, M.; Jimenez, Maria Soledad; Suarez, Guillermo Martin; Kiebacher, T.; Lebouvier, M.; Long, D.G.; Maity, D.; Ochyra, R.; Parnikoza, I.; Plášek, V.; Fialová, L.; Skoupá, Z.; Poponessi, S.; Aleffi, M.; Sabovljević, M.S.; Sabovljević, A.D.; Saha, P.; Aziz, M.N.; Sawicki, J.; Suleiman, M.; Sun, B.-Y.; Vá?a, J.; Wójcik, T.; Yoon, Y.-J.; Żarnowiec, J.; Larraín, J.

The N-terminal pre-A region of Mycobacterium tuberculosis 2/2HbN promotes NO-dioxygenase activity Pesce, Alessandra; Bustamante, Juan Pablo; Bidon Chanal, Axel; Boechi, Leonardo; Estrin, Dario Ariel; Luque, Francisco Javier; Sebilo, Anne; Guertin, Michel; Bolognesi, Martino; Ascenzi, Paolo; Nardini, Marco A unique defense mechanisms by which Mycobacterium tuberculosis protects itself from nitrosative stress is based on the O2-dependent NO-dioxygenase (NOD) activity of truncated hemoglobin 2/2HbN (Mt2/2HbN). The NOD activity largely depends on the efficiency of ligand migration to the heme cavity through a two-tunnel (long and short) system; recently, it was also correlated with the presence at the Mt2/2HbN N-terminus of a short pre-A region, not conserved in most 2/2HbNs, whose deletion results in a drastic reduction of NO scavenging. In the present study, we report the crystal structure of Mt2/2HbN-ΔpreA, lacking the pre-A region, at a resolution of 1.53 Å. We show that removal of the pre-A region results in long range effects on the protein C-terminus, promoting the assembly of a stable dimer, both in the crystals and in solution. In the Mt2/2HbN-ΔpreA dimer, access of heme ligands to the short tunnel is hindered. Molecular dynamics simulations show that the long tunnel branch is the only accessible pathway for O2-ligand migration to/from the heme, and that the gating residue Phe(62)E15 partly restricts the diameter of the tunnel. Accordingly, kinetic measurements indicate that the kon value for peroxynitrite isomerization by Mt2/2HbN-ΔpreA-Fe(III) is four-fold lower relative to the full-length protein, and that NO scavenging by Mt2/2HbN-ΔpreA-Fe(II)-O2 is reduced by 35-fold. Therefore, we speculate that Mt2/2HbN evolved to host the pre-A region as a mechanism for preventing dimerization, thus reinforcing the survival of the microorganism against the reactive nitrosative stress in macrophages. Database Coordinates and structure factors have been deposited in the Protein Data Bank under accession number 5AB8. Removal of the pre-A region in M. tuberculosis 2/2HbN (Mt2/2HbN-ΔpreA) results in dimerization and in a reduced access to the heme pocket. Kinetic measurements indicate a 4-fold decrease in kon for peroxynitrite isomerization and a 35-fold decrease in NO-scavenging relative to full-length Mt2/2HbN. Thus, the pre-A region might be involved in reinforcing survival of the microorganism against nitrosative stress in macrophages.

Eprinomectin accumulation in Rhipicephalus (Boophilus) microplus: Pharmacokinetic and efficacy assessment Lifschitz, Adrian Luis; Nava, Santiago; Mangold, Atilio Jose; Imperiale, Fernanda Andrea; Ballent, Mariana; Canevari, J.; Lanusse, Carlos Edmundo Eprinomectin (EPM) is a macrocyclic lactone used against endo-ectoparasites without withdrawal time in milk and meat after its pour-on administration at 0.5 mg/kg. Previous experiments evaluated the efficacy of EPM against Rhipicephalus (Boophilus) microplus in cattle. This study assessed EPM efficacy against R. (B.) microplus after topical administration at two dose rates and investigated the relationship between EPM systemic exposure in the host and drug concentrations accumulated in ticks recovered from treated animals. A standardized pharmaco-parasitological study was performed in two phases. In phase 1 eighteen Braford cattle naturally infected with R. (B.) microplus were divided into three experimental groups with a similar level of infestation (Kruskal-Wallis test, P > 0.05): control group and treated groups with EPM pour-on (1 and 1.5 mg/kg). Samples of heparinized blood and ticks at different life stages were taken between 0 and 21 days (d) post-administration to measure EPM concentrations by HPLC. The efficacy trial (phase 2) included eighteen Braford calves naturally infected with R. (B.) microplus divided into control group and 1 mg/kg and 1.5 mg/kg EPM treated groups. Female ticks (4.5-8 mm) on cattle were counted between 1 and 23 days post-treatment to evaluate the efficacy of EPM. The reproductive efficiency index (REI) and the fertility efficiency index (FEI) were evaluated. Plasma concentrations of EPM showed a linear relationship with the level of dose rate administered. Peak plasma concentrations were within a range between 13.8 and 90 ng/ml, which guarantee milk drug concentrations below the maximum residues level. High EPM concentrations were detected in ticks. EPM concentrations in R. (B.) microplus were correlated to plasma concentrations between 1.25 days and 21 days post-administration (r 0.84; P < 0.05). EPM efficacy calculated using the Henderson-Tilton formula was 98.9% and 99.1% (7 days post-administration) and 100% (23 days post-administration) after EPM treatment at 1 and 1.5 mg/kg, respectively. EPM administered at 1.5 mg/kg also showed a significantly higher deleterious effect on tick fertility as measured by FEI (P < 0.01). Therefore, treatment with EPM may be useful for controlling ticks in cattle, particularly in dairy production systems.

Dibujando la nación desdibujando al enemigo: Imágenes de movilización bélica en la prensa de guerra paraguaya, 1867-1868 Johansson, Maria Lucrecia Between 1864 and 1870, the Paraguayan forces clashed with the armies of Argentina, Brazil and Uruguay, in what was called the War of the Triple Alliance (1864-1870). During that war, the Paraguayan government revolutionized journalism by the creation of two illustrated newspapers: El Centinela and Cabichuí (1867-1868). The engravings of these newspapers created a system of opposition we/they that rested on opposite values and in the opposition between negative and positive images. The aim of this paper is to analyse how the press built negative images of the enemy and how those images were the basis for creating a positive representation of Paraguay.

Defining the HLA class I-associated viral antigen repertoire from HIV-1-infected human cells Ternette, Nicola; Yang, Hongbing; Partridge, Thomas; Llano, Anuska; Cedeño, Samandhy; Fischer, Roman; Charles, Philip D.; Dudek, Nadine L.; Mothe, Beatriz; Crespo, Manuel; Fischer, William M.; Korber, Bette T. M.; Nielsen, Morten; Borrow, Persephone; Purcell, Anthony W.; Brander, Christian; Dorrell, Lucy; Kessler, Benedikt M.; Hanke, Tomáš Recognition and eradication of infected cells by cytotoxic T lymphocytes is a key defense mechanism against intracellular pathogens. High-throughput definition of HLA class I-associated immunopeptidomes by mass spectrometry is an increasingly important analytical tool to advance our understanding of the induction of T-cell responses against pathogens such as HIV-1. We utilized a liquid chromatography tandem mass spectrometry workflow including de novo-assisted database searching to define the HLA class I-associated immunopeptidome of HIV-1-infected human cells. We here report for the first time the identification of 75 HIV-1-derived peptides bound to HLA class I complexes that were purified directly from HIV-1-infected human primary CD4+ T cells and the C8166 human T-cell line. Importantly, one-third of eluted HIV-1 peptides had not been previously known to be presented by HLA class I. Over 82% of the identified sequences originated from viral protein regions for which T-cell responses have previously been reported but for which the precise HLA class I-binding sequences have not yet been defined. These results validate and expand the current knowledge of virus-specific antigenic peptide presentation during HIV-1 infection and provide novel targets for T-cell vaccine development.

Esfera pública y redes sociales en Internet: ¿Qué es lo nuevo en Facebook?; Public sphere and social networks resources on Internet: What's new in Facebook? Raimondo Anselmino, Natalia; Reviglio, María Cecilia; Diviani, Ricardo Habitamos en sociedades altamente mediatizadas ya no sólo completamente atravesadas por la acción de los medios masivos de comunicación sino, también, por las nuevas tensiones que asume el proceso de mediatización a partir del desarrollo de las redes sociales en Internet. Al reconocer la naturaleza ambiental y constructiva de los medios masivos de comunicación es posible, también, considerar a la mediatización como modalidad nuclear de construcción de la esfera pública. En dicho contexto, este escrito inquiere sobre los modos en que el funcionamiento de Facebook y los discursos allí expuestos participan en la configuración de la esfera pública contemporánea, así como, además, sobre el grado de novedad que presenta dicha intervención respecto de la ejercida por los tradicionales medios masivos de comunicación. En función de articular las reflexiones expuestas con algunos de los ejes que ha asumido el debate teórico suscitado por el análisis que realizó Habermas sobre la génesis y las transformaciones estructurales de la vida pública, este texto se concentra en los siguientes tres aspectos: la gestión de la visibilidad, de la puesta en público o publicación; el lugar que ocupan el diálogo, la deliberación y el disenso; la condición múltiple y móvil de la esfera pública actual.; We live in highly mediatizated societies and not only completely traversed by the action of the mass media but also by new tensions that assumes the mediatization process from the development of social networks resources on Internet. Recognizing the environmental and constructive nature of the mass media, it is also possible to consider mediatization as nuclear mode of construction of the public sphere. In this context, this paper asks about the ways in which the operation of Facebook and discourses posted there shape contemporary public sphere, and also the degree of novelty of such intervention with respect to that exerted by the traditional mass media. For the purpose of joint thinkings reflections exposed with some of the areas that has taken the theoretical debate surrounding the Habermas's analysis about the genesis and structural transformations of public life, this text focuses on the following three aspects: the management of visibility, of commissioning public or publication; the place of dialogue, deliberation and dissent; the multiple and mobile status of the current public sphere.

La desorganización de la acción de clase en la Argentina reciente y los problemas conceptuales para el estudio del conflicto obrero; The Disorganization of the Class Action in the Recent Argentina and the Conceptual Problems for the Study of Labor Conflict Piva, Adrián Este artículo se propone discutir algunas tendencias del conflicto obrero y su lugar en el conflicto social en Argentina desde 1989 como una aproximación a los procesos de formación y desorganización de la acción colectiva de clase de los asalariados. Simultáneamente, trata el problema de las categorías de análisis del conflicto social, particularmente el laboral, para la medición de la conflictividad. Para esto se implementó una estrategia de análisis cuantitativo del conflicto a partir de datos de producción propia y de otros investigadores. La principal hipótesis es que durante la década de 1990 se desarrolló en Argentina un proceso de desorganización de la acción de clase de los asalariados, caracterizado por la pérdida de peso social de las acciones de clase dentro del conjunto de las luchas sociales y la fragmentación de las acciones de la clase obrera. Dicho proceso puso en crisis las formas tradicionales de conceptualizar y medir el conflicto social, particularmente el obrero, y exige la adecuación de los instrumentos teóricos y metodológicos con el fin de aprehender las tendencias disímiles del conflicto obrero y social.; This article discusses some trends of the labor conflict and its role in the social conflict in Argentina since 1989 as an approximation to the processes of formation and disorganization of the collective action by the salaried class. Simultaneously, it addresses the problem of the categories of analysis of the social conflict; particularly, of the labor conflict, for the measurement of the amount of conflict. In order to do this, a strategy of quantitative analysis has been implemented, whose point of departure were data of conflict both retrieved by us and from other researchers. The main hypothesis is that, during the 90s, a process of disorganization in the salaried class took place in Argentina, characterized by the loss of social force of the class action agency within the set of social struggles, and the fragmentation of the actions by the working class. This process calls into question the traditional methods for conceptualizing and measuring social conflict, particularly in the workers, and evidences the need to improve and adapt theoretical and methodological tools in order to comprehend the different trends within the social and labor conflict.

Evolutionary and Functional Relationships in the Truncated Hemoglobin Family Bustamante, Juan Pablo; Radusky, Leandro Gabriel; Boechi, Leonardo; Estrin, Dario Ariel; Ten Have, Arjen; Marti, Marcelo Adrian Predicting function from sequence is an important goal in current biological research, and although, broad functional assignment is possible when a protein is assigned to a family, predicting functional specificity with accuracy is not straightforward. If function is provided by key structural properties and the relevant properties can be computed using the sequence as the starting point, it should in principle be possible to predict function in detail. The truncated hemoglobin family presents an interesting benchmark study due to their ubiquity, sequence diversity in the context of a conserved fold and the number of characterized members. Their functions are tightly related to O2affinity and reactivity, as determined by the association and dissociation rate constants, both of which can be predicted and analyzed using in-silico based tools. In the present work we have applied a strategy, which combines homology modeling with molecular based energy calculations, to predict and analyze function of all known truncated hemoglobins in an evolutionary context. Our results show that truncated hemoglobins present conserved family features, but that its structure is flexible enough to allow the switch from high to low affinity in a few evolutionary steps. Most proteins display moderate to high oxygen affinities and multiple ligand migration paths, which, besides some minor trends, show heterogeneous distributions throughout the phylogenetic tree, again suggesting fast functional adaptation. Our data not only deepens our comprehension of the structural basis governing ligand affinity, but they also highlight some interesting functional evolutionary trends.

Prisión política y destierro en la Argentina dictatorial: Materiales y preguntas para la construcción de nuevos objetos de estudio; Political imprisonment and exile in the dictatorial Argentina: Materials and questions for the construction of new objects of study Jensen, Silvina Inés; Montero, María Lorena Este artículo se propone analizar las formas de abordaje de las relaciones entre cárcel y exilio haciendo foco en escenarios, luchas y actores concretos del pasado reciente argentino, a partir del análisis de materiales producidos por los desterrados en su accionar anti-dictatorial, en diálogo con otros emanados del propio sistema penitenciario o con las memorias de los protagonistas.; This article aims to discuss ways of addressing the relationship between prison and exile by focusing on scenarios, struggles and specific actors of the Argentine recent past, from the analysis of materials produced by the exiles in their anti-dictatorial action, in dialogue with others issued the correctional system or the memories of the protagonists.

Taxonomy, affinities, and paleobiology of the tiny metatherian mammal Minusculodelphis, from the early Eocene of South America Oliveira, Edison V.; Zimicz, Ana Natalia; Goin, Francisco Javier With less than 3 g of estimated body mass, the early Eocene Minusculodelphis minimus Paula Couto (Mammalia, Metatheria, Jaskhadelphyidae) is one of the smallest mammals, living or extinct. It has alternatively been regarded as adidelphid or a derorhynchid Bameridelphian, or even as an eometatherian marsupial. Here, we describe a new species of Minusculodelphis coming from the same locality (Itaboraí Quarry, Brazil) and age (Itaboraian age) of the type species of the genus. It differs from M. minimus in its larger size and several dental characters. The new species offers data on the upper dentition and femur, which are unknown in the type species. Compared to other Paleogene metatherians,Minusculodelphis shows closer relationships with Jaskhadelphys, from the early Paleocene of Tiupampa, Bolivia, as well as with Kiruwamaq, from the late Eocene-early Oligocene of Perú. A cladistic analysis places all three genera within the family Jaskhadelphyidae (Metatheria, Order indet.), which includes small to tiny, insectivorous-like metatherians. We argue that insectivory (soft insects) is the best-supported diet for both species of Minusculodelphis, and that the most probable microhabitat for them was the understorey or leaf litter of tropical, rain forested environments.

Partition of some key regulating services in terrestrial ecosystems: Meta-analysis and review Viglizzo, Ernesto Francisco; Jobbagy Gampel, Esteban Gabriel; Ricard, Maria Florencia; Paruelo, José Our knowledge about the functional foundations of ecosystem service (ES) provision is still limited and more research is needed to elucidate key functional mechanisms. Using a simplified eco-hydrological scheme, in this work we analyzed how land-use decisions modify the partition of some essential regulatory ES by altering basic relationships between biomass stocks and water flows. A comprehensive meta-analysis and review was conducted based on global, regional and local data from peer-reviewed publications. We analyzed five datasets comprising 1348 studies and 3948 records on precipitation (PPT), aboveground biomass (AGB), AGB change, evapotranspiration (ET), water yield (WY), WY change, runoff (R) and infiltration (I). The conceptual framework was focused on ES that are associated with the ecological functions (e.g., intermediate ES) of ET, WY, R and I. ES included soil protection, carbon sequestration, local climate regulation, water-flow regulation and water recharge. To address the problem of data normality, the analysis included both parametric and non-parametric regression analysis. Results demonstrate that PPT is a first-order biophysical factor that controls ES release at the broader scales. At decreasing scales, ES are partitioned as result of PPT interactions with other biophysical and anthropogenic factors. At intermediate scales, land-use change interacts with PPT modifying ES partition as it the case of afforestation in dry regions, where ET and climate regulation may be enhanced at the expense of R and water-flow regulation. At smaller scales, site-specific conditions such as topography interact with PPT and AGB displaying different ES partition formats. The probable implications of future land-use and climate change on some key ES production and partition are discussed.

Comando de Organización: un peronismo plebeyo, combativo y nacionalista (1961-1976); Command of Organization: a plebeian, combative and nationalistic Peronism (1961-1976) Denaday, Juan Pedro En el presente artículo se sintetizan las principales conclusiones de una primera investigación sobre el Comando de Organización de la Juventud Peronista. Se comienza por reconstruir las redes militantes de las cuales surgieron los activistas que, liderados por el dirigente peronista Alberto Brito Lima, fundaron la agrupación. Se desarrolla una descripción y análisis de aquellos rasgos políticos, ideológicos, sociológicos y culturales que se identifican como los más relevantes a los fines de hacer una caracterización del Comando de Organización. Se indaga cómo la muerte de varios de sus integrantes en episodios políticos violentos dio sitio a la construcción de un martirologio funcional a la recreación de una mística heroica, que alimentó un militantismo combativo ideológicamente asociado a un imaginario de cuño nacionalista. La reconstrucción de la historia de esta agrupación nacida a comienzos de la década del sesenta, nos aporta información que consideramos significativa para interpretar la beligerante interna justicialista acontecida en el primer lustro de la década del setenta. En la medida que estos activistas peronistas tuvieron un protagonismo en dichos acontecimientos, su estudio brinda elementos para hacer inteligible la dinámica de ese controvertido período histórico signado por el fenómeno de la violencia política.; In this article the main findings of the first investigation about the group Command of Organization of the Peronist Youth are presented. It begins by rebuilding the militant networks out of which emerged activists, led by Peronist leader Alberto Brito Lima, that founded the group. A description and analysis is made concerning those political, ideological, sociological and cultural characteristics that are identified as the most relevant ones for the purposes of making a characterization of the Command of Organization. It is shown how the death of several of its members in politically violent episodes, gave place to the construction of a martyrdom that was functional to the recreation of a heroic mystique that fueled a combative militancy ideologically associated to a nationalist imaginary. The reconstruction of the history of this group, born in the early sixties, gives us information that we consider significant to interpret the belligerent internal differences within Peronism occurred in the first half of the seventies. Since these Peronist activists played a protagonic role in these events, their analysis provides us with elements to make intelligible the dynamics of the controversial historical period marked by the phenomenon of political violence.

Electrochemical formation and characterization of Au nanostructures on a highly ordered pyrolytic graphite surface Arroyo Gomez, Jose Joaquin; Zubieta, Carolina Edith; Ferullo, Ricardo; Garcia, Silvana Graciela The electrochemical formation of Au nanoparticles on a highly ordered pyrolytic graphite (HOPG) substrate using conventional electrochemical techniques and ex-situ AFM is reported. From the potentiostatic current transients studies, the Au electrodeposition process on HOPG surfaces was described, within the potential range considered, by a model involving instantaneous nucleation and diffusion controlled 3D growth, which was corroborated by the microscopic analysis. Initially, three-dimensional (3D) hemispherical nanoparticles distributed on surface defects (step edges) of the substrate were observed, with increasing particle size at more negative potentials. The double potential pulse technique allowed the formation of rounded deposits at low deposition potentials, which tend to form lines of nuclei aligned in defined directions leading to 3D ordered structures. By choosing suitable nucleation and growth pulses, one-dimensional (1D) deposits were possible, preferentially located on step edges of the HOPG substrate. Quantum-mechanical calculations confirmed the tendency of Au atoms to join selectively on surface defects, such as the HOPG step edges, at the early stages of Au electrodeposition.

Bringing High-Rate, CO2-Based Microbial Electrosynthesis Closer to Practical Implementation through Improved Electrode Design and Operating Conditions Jourdin, Ludovic; Freguia, Stefano; Flexer, Victoria; Keller, Jurg The enhancement of microbial electrosynthesis (MES) of acetate from CO2 to performance levels that could potentially support practical implementations of the technology must go through the optimization of key design and operating conditions. We report that higher proton availability drastically increases the acetate production rate, with pH 5.2 found to be optimal, which will likely suppress methanogenic activity without inhibitor addition. Applied cathode potential as low as −1.1 V versus SHE still achieved 99% of electron recovery in the form of acetate at a current density of around −200 A m–2. These current densities are leading to an exceptional acetate production rate of up to 1330 g m–2 day–1 at pH 6.7. Using highly open macroporous reticulated vitreous carbon electrodes with macropore sizes of about 0.6 mm in diameter was found to be optimal for achieving a good balance between total surface area available for biofilm formation and effective mass transfer between the bulk liquid and the electrode and biofilm surface. Furthermore, we also successfully demonstrated the use of a synthetic biogas mixture as carbon dioxide source, yielding similarly high MES performance as pure CO2. This would allow this process to be used effectively for both biogas quality improvement and conversion of the available CO2 to acetate.

BEC-BCS crossover in a cold and magnetized two color NJL model Duarte, Dyana C.; Allen, Pablo Guillermo; Farias, R. L. S.; Manso, Pedro H. A.; Ramos, Rudnei O.; Scoccola, Norberto Nerio The BEC-BCS crossover for a Nambu-Jona-Lasinio (NJL) model with diquark interactions is studied in the presence of an external magnetic field. Particular attention is paid to different regularization schemesused in the literature. A thorough comparison of results is performed for the case of a cold and magnetized two-color NJL model. According to our results, the critical chemical potential for the BEC transition exhibits a clear inverse magnetic catalysis effect for magnetic fields in the range 1 ≲ eB=m2π≲ 20. As for the BEC-BCS crossover, the corresponding critical chemical potential is very weakly sensitive to magnetic fields up to eB ∼ 9m2π, showing a much smaller inverse magnetic catalysis as compared to the BECtransition, and displays a strong magnetic catalysis from this point on.

Carrageenan and agaran structures from the red seaweed Gymnogongrus tenuis Perez Recalde, Maria Mercedes; Canelon Gonzalez, Dilsia Josefina; Compagnone, Reinaldo S.; Matulewicz, Maria Cristina; Cerezo, Alberto; Ciancia, Marina The galactan system biosynthesized by the red seaweed Gymnogongrus tenuis (Phyllophoraceae) is con-stituted by major amounts of /-carrageenans, with predominance of -structures, which were isolatedby extraction with hot water in high yield (∼45%). A small amount of non-cyclized carrageenans mostlyof the -type was also obtained. Besides, 12% of these galactans are agaran structures, which were presentin major quantities in the room temperature water extracts, but they were also found in the hot waterextract. They are constituted by 3-linked -d-galactose units partially substituted on C-6 with sulfate orsingle stubs of -d-xylose and 4-linked residues that comprise -l-galactose units partially sulfated ormethoxylated on C-3 or sulfated on C-3 and C-6 and 3,6-anhydro--l-galactose. Related structural pat-terns were previously found for agarans synthesized by other carrageenophytes. Results presented hereshow that these agarans are low molecular weight molecules independent of the carrageenan structures,with strong interactions between them.

Rickettsial infection in ticks infesting wild birds from two eco-regions of Argentina; Infecção por riquétsias em carrapatos de aves silvestres em duas ecorregiões da Argentina Flores, Fernando Sebastián; Borges Costa, Francisco; Nava, Santiago; Diaz, Luis Adrian; Labruna, Marcelo Bahía Several tick-borne Rickettsia species are recognized human pathogens in Argentina. Here we evaluated rickettsial infection in ticks collected on passerine birds during 2011-2012 in two eco-regions of Argentina. The ticks were processed by molecular analysis through polymerase chain reaction (PCR) detection and DNA sequencing of fragments of two rickettsial genes, gltA and ompA. A total of 594 tick specimens (532 larvae and 62 nymphs), representing at least 4 species (Amblyomma tigrinum, Ixodes pararicinus, Haemaphysalis juxtakochi, Haemaphysalis leporispalustris), were evaluated. At least one A. tigrinum larva, collected on Coryphospingus cucullatus in Chaco Seco, was infected with Rickettsia parkeri, whereas at least 12 larvae and 1 nymph of I. pararicinus, collected from Troglodytes aedon, Turdus amaurochalinus, Turdus rufiventris, C. cucullatus and Zonotrichia capensis, were infected with an undescribed Rickettsia agent, genetically related to several rickettsial endosymbionts of ticks of the Ixodes ricinus complex. R. parkeri is a recognized human pathogen in several American countries including Argentina, where a recent study incriminated A. tigrinum as the potential vector of R. parkeri to humans. Birds could play an important role in dispersing R. parkeri-infected A. tigrinum ticks. Additionally, we report for the first time a rickettsial agent infecting I. pararicinus ticks.; Algumas espécies de Rickettsia transmitidas por carrapatos são reconhecidos como patógenos humanos na Argentina. Este presente trabalho avaliou a infecção por Rickettsia em carrapatos coletados em aves passeriformes, durante 2011-2012, em duas ecorregiões da Argentina. Os carrapatos foram processados pela reação em cadeia da polimerase (PCR) e sequenciamento de DNA de dois genes de Rickettsia: gltA e ompA. Ao todo, 594 amostras de carrapatos (532 larvas e 62 ninfas), representando pelo menos 4 espécies (Amblyomma tigrinum, Ixodes pararicinus, Haemaphysalis juxtakochi, Haemaphysalis leporispalustris), foram avaliadas. Pelo menos uma larva de A. tigrinum, coletada de Coryphospingus cucullatus no Chaco Seco, estava infectada com Rickettsia parkeri, enquanto pelo menos 12 larvas e 1 ninfa de I. pararicinus, coletadas de Troglodytes aedon, Turdus amaurochalinus, Turdus rufiventris, C. cucullatus e Zonotrichia capensis estavam infectadas com Rickettsia sp., geneticamente relacionada a vários endossimbiontes riquetsiais de carrapatos do complexo Ixodes ricinus. R. parkeri é reconhecidamente um patógeno humano em alguns países americanos, incluindo a Argentina, onde um estudo recente incriminou A. tigrinum como um provável vetor. Aves poderiam desempenhar um papel importante na dispersão de carrapatos A. tigrinum infectados por R. parkeri. Em adição, relata-se pela primeira vez a infecção por Rickettsia em I. pararicinus.