Importancia de la Geodiversidad. Método de Inventarización y Valoración del Patrimonio Geológico; Geodiversity importance. An inventory and assessment method for Geoheritage Medina, Walter Manuel En el presente trabajo se plantea un método de análisis cuantitativo del patrimonio geológico de un área elegida. Esta importancia nace del hecho de que el patrimonio natural -donde se involucra a la riqueza geológica-, está cada vez más amenazada producto de actividades tales como la agricultura en grandes superficies, grandes infraestructuras, etc., trayendo aparejado un deterioro o incluso la desaparición de la herencia geológica, lo cual se traduce a un empobrecimiento del patrimonio de todos y de la historia geológica del mundo. El interés que se despertó por proteger estos bienes únicos e irreemplazables llevó al desarrollo de distintas técnicas o herramientas que contribuyen a la geoconservación. En este sentido, el desarrollo de la geoconservación a nivel internacional es bastante heterogéneo y también lo son sus planes de acción para conservar las riquezas geológicas y geomorfológicas. Existen varios métodos para esta práctica, en este caso se presenta una metodología en su etapa de inventario y cuantificación de los potenciales geositios.; A geoheritage quantitative analysis method applied to a chosen area is proposed. The natural heritage, involving geological richness, is increasingly threatened by activities such as large surface agriculture, infrastructures, etc., endangering the geological heritage, which translates to an impoverishment of the general heritage and the global geological history. The interest aroused by protecting these unique and irreplaceable assets, led to the development of different techniques or tools to geoconservation. As a matter of fact, the international development of geoconservation is quite heterogeneous and so are their action plans for protecting geological and geomorphological wealth. Several methods were defined for this practice, and in this opportunity, a methodology is proposed within the initial phase of inventory and quantification of potential geosites.

Pueblo, comunidad y mito en Juan Moreira de Leonardo Favio y en Facundo. La sombra del Tigre de Nicolás Sarquís Suárez, Nicolás El trabajo aborda dos transposiciones de textos de la literatura argentina del siglo XIX que fueron llevados al cine en el último tercio del siglo XX: Juan Moreira (Leonardo Favio, 1973) y Facundo. La sombra del tigre (Sarquís, 1995). A partir de la inscripción de ambos films en sus respectivos contextos histórico-políticos, se apunta a contrastar los modelos comunitarios que emanan de cada una de las obras, así como las figuraciones de los conceptos de pueblo y mito que ellas proponen.; This article addresses two film transpositions of texts from the Argentine literature of the 19th Century: Juan Moreira (Leonardo Favio, 1973) and Facundo. La sombra del tigre (Nicolás Sarquís, 1995), both produced in the last third of the 20th century. Through the inscription of both films in their respective historic and political contexts, I aim to contrast the community models that each film implies, as well as the corresponding figurations of the concepts of people and myth.; Este trabalho aborda duas transcrições de textos da literatura argentina do sé- culo XIX que foram adaptados ao cinema no último terço do século XX: Juan Moreira (Leonardo Favio, 1973), Facundo e La sombra del tigre (Nicolás Sarquís, 1995). A partir da inscrição de ambos os filmes em seus respectivos contextos histórico-político, pretende-se contrastar os modelos comunitários que emanam de cada uma das obras, bem como as figurações dos conceitos de povo e mito que elas propõem.

Decoherent time-dependent transport beyond the Landauer-Büttiker formulation: A quantum-drift alternative to quantum jumps Fernández, Lucas Jonatan; Pastawski, Horacio Miguel We develop and implement a model for decoherence in time-dependent transport. Inspired in a dynamical formulation of the Landauer-Büttiker equations, it boils down into a form of wave function that undergoes a smooth stochastic drift of the phase in a local basis, the quantum-drift (QD) model. This drift is nothing else but a local energy fluctuation. Unlike quantum-jumps (QJ) models, no jumps are present in the density as the evolution is unitary. As a first application, we address the transport through a resonant state |0〉 that undergoes decoherence. Its numerical resolution shows the equivalence with the decoherent steady-state transport in presence of a Büttiker's voltage probe. In order to test the dynamics we consider two many-spin systems, which are cases of experimental interest, where a local energy fluctuation is a natural phenomenon. A two-spin system is reduced to a two-level system (TLS) that oscillates among |0〉≡|↑↓〉 and |1〉≡|↓↑〉. We show that the QD model recovers not only the exponential damping of the oscillations in the low perturbation regime, but also the nontrivial bifurcation of the damping rates at a critical point, i.e., the quantum dynamical phase transition. We also address the spin-wave-like dynamics of local polarization in a spin chain. By averaging over Ns realizations, the QD solution has about half the dispersion respect to the mean dynamics than QJ. By evaluating the Loschmidt echo (LE), we find that the pure states |0〉≡|↑↓〉 and |1〉≡|↓↑〉 are quite robust against the local decoherence. In contrast, the LE, and hence coherence, decays faster when the system is in a superposition state (|↑↓〉±|↓↑〉)/2, which is consistent with the general trend recently observed in spin systems through NMR. Because of its simple implementation, the method is well suited to assess decoherent transport problems as well as to include decoherence in both one-body and many-body dynamics.

Exogenous GM1 ganglioside increases accumbal BDNF levels in rats Valdomero, Analía; Perondi, María Cecilia; Orsingher, Otto Alberto; Cuadra, Gabriel R. Gangliosides are compounds that are abundant throughout the CNS, participating actively in neuroplasticity. We previously described that exogenous GM1 ganglioside pretreatment enhances the rewarding properties of cocaine, evidenced by a lower number of sessions and/or dosage necessary to induce conditioned place preference (CPP). Since GM1 pretreatment did not modify cocaine's pharmacokinetic parameters, we suspected that the increased rewarding effect found might be mediated by BDNF, a neurotrophic factor closely related to cocaine addiction. This study was performed to investigate the possibility that GM1 may induce changes in BDNF levels in the nucleus accumbens (NAc), a core structure in the brain's reward circuitry, of rats submitted to three conditioning sessions with cocaine (10. mg/kg, i.p.). The results demonstrate that GM1 administration, which showed no rewarding effect by itself in the CPP, induced a significant increase of BDNF protein levels in the NAc, which may account for the increased rewarding effect of cocaine shown in the CPP paradigm.

The pattern of secreted molecules during the co-inoculation of alfalfa plants with Sinorhizobium meliloti and Delftia sp. strain JD2: An interaction that improves plant yield Morel, M.A.; Cagide, C.; Minteguiaga, M.A.; Dardanelli, Marta Susana; Castro Sowinski, S. Delftia sp. strain JD2 is a plant-growth-promoting bacterium that enhances legume nodulation and growth, acting as nodule-assisting bacterium during the co-inoculation of plants with rhizobial strains. In this work, we evaluate how the co-inoculation of alfalfa with Sinorhizobium meliloti U143 and JD2 increases plant yield under greenhouse conditions and we analyze the pattern of secreted bioactive compounds which may be involved in the microbe-plant communication. The chemical composition of extracellular cultures (EC) produced in hydroponic conditions (collected 4, 7, and 14 days after bacterial treatment) were characterized using different chromatographic and elucidation techniques. In addition, we assessed the effect that plant irrigation with cell-free EC, produced during co-inoculation experiments, would have on plant yield. Results showed increased alfalfa shoot and root matter, suggesting that U143-JD2 co-inoculation might be a beneficial agricultural practice. The pattern of secreted secondary metabolites among treatments showed important differences. Qualitative and quantitative changes in phenolic compounds (including flavonoids), organic acids, and volatile compounds were detected during the early microbe-plant interaction, suggesting that the production of some molecules positively affects the microbe-plant association. Finally, the irrigation of co-inoculated plants with cell-free EC under greenhouse conditions increased plant yield over agronomic expectations. This effect might be attributed to the bioactive secondary metabolites incorporated during the irrigation.

Nanointegracion: obtención controlada de nanoestructuras de oxido de Grafeno reducido interconectadas en áreas macroscopicamente extendidas mediante la técnica de Langmuir Blodgett Herrera, Facundo Carlos; Ramallo Lopez, Jose Martin; Morales, Gustavo Marcelo; Lacconi, Gabriela Ines; Sanchez, Rodolfo Daniel; Lohr, Javier Hernán; Requejo, Felix Gregorio El objetivo del presente trabajo es obtener películas delgadas de óxido de grafeno (GO) empleando la técnica de Langmuir-Blodgett (L-B) y posteriormente producir la reducción de la película, analizando distintos métodos, para obtener óxido de grafeno reducido (rGO). Con el objetivo de caracterizar als muestras de GO y rGO, las mismas fueron estudiadas por microscopía de fuerza atómica (AFM), micro-Raman y espectroscopía fotoelectrónica de rayos X (XPS) con resolución espacial nanométrica. Se realizaron además medidas de conductividad tanto a escala macro como nanométrica utilizando una estación de prueba y un nanomanipulador acoplado a un equipo de microscopía electrónica de barrido (SEM). Finalmente se correlacionaron el estado químico, la estructura y los defectos presentes en las películas delgadas de rGO con sus propiedades de transporte.

Plasma deposition of silver nanoparticles on ultrafiltration membranes: antibacterial and antibiofouling properties Cruz, Mercedes Cecilia; Ruano Sandoval, Gonzalo Javier; Wolf, Marcus; Hecker, Dominic; Castro Vidaurre, Elza Fani; Schmittgens, Ralph; Rajal, Verónica Beatriz tA novel and versatile plasma reactor was used to modify polyethersulphone commercial membranes. The equipmentwas applied to: (i) functionalize the membranes with low-temperature plasmas, (ii) deposit a film of poly(methylmethacrylate) (PMMA) by Plasma Enhanced Chemical Vapor Deposition (PECVD) and, (iii) deposit silver nanopar-ticles (SNP) by gas flow sputtering. Each modification process was performed in the same reactor consecutively,without exposure of the membranes to atmospheric air. Scanning electron microscopy and transmission electronmicroscopy were used to characterize the particles and modified membranes. SNP are evenly distributed on the mem-brane surface. Particle fixation and transport inside membranes were assessed before- and after-washing assays byX-ray photoelectron spectroscopy depth profiling analysis. PMMA addition improved SNP fixation. Plasma-treatedmembranes showed higher hydrophilicity. Anti-biofouling activity was successfully achieved against Gram-positive(Enterococcus faecalis) and -negative (Salmonella) Typhimurium bacteria. Therefore, disinfection by ultrafiltrationshowed substantial resistance to biofouling. The post-synthesis functionalization process developed provides a moreefficient fabrication route for anti-biofouling and anti-bacterial membranes used in the water treatment field. To thebest of our knowledge, this is the first report of a gas phase condensation process combined with a PECVD procedurein order to deposit SNP on commercial membranes to inhibit biofouling formation.

Sim1 is required for the migration and axonal projections of V3 interneurons in the developing mouse spinal cord Blacklaws, Jake; Deska Gauthier, Dylan; Jones, Christopher T.; Petracca, Yanina Luján; Liu, Mingwei; Zhang, Han; Fawcett, James P.; Glover, Joel C.; Lanuza, Guillermo Marcos; Zhang, Ying V3 spinal interneurons (INs) are a group of excitatory INs that play a crucial role in producing balanced and stable gaits in vertebrate animals. In the developing mouse spinal cord, V3 INs arise from the most ventral progenitor domain and form anatomically distinctive subpopulations in adult spinal cords. They are marked by the expression of transcription factor Sim1 postmitotically, but the function of Sim1 in V3 development remains unknown. Here, we used Sim1(Cre) ;tdTomato mice to trace the fate of V3 INs in a Sim1 mutant versus control genetic background during development. In Sim1 mutants, V3 INs are produced normally and maintain a similar position and organization as in wild types before E12.5. Further temporal analysis revealed that the V3 INs in the mutants failed to migrate properly to form V3 subgroups along the dorsoventral axis of the spinal cord. At birth, in the Sim1 mutant the number of V3 INs in the ventral subgroup was normal, but they were significantly reduced in the dorsal subgroup with a concomitant increase in the intermediate subgroup. Retrograde labeling at lumbar level revealed that loss of Sim1 led to a reduction in extension of contralateral axon projections both at E14.5 and P0 without affecting ipsilateral axon projections. These results demonstrate that Sim1 is essential for proper migration and the guidance of commissural axons of the spinal V3 INs.

Persistent effect of organic matter pulse on a sandy soil of semiarid Patagonia Gonzalez Polo, Marina; Kowaljow, Esteban; Castán, Elisa; Sauzet, Ophelie; Mazzarino, Maria Julia Studies of degraded semiarid regions have shown that organic residue addition is a sound restoration alternative. We examined the effects of a single dose (40 Mg ha−1) of biosolids compost (BC) and compost of the organic fraction of municipal solid waste (MC) 6 years after they were applied to a sandy soil of NW Patagonia. Results were compared with those of inorganic fertilization (IF, 100 kg N+35 kg P ha−1) treatment and of unamended control. We measured plant cover, biomass, and diversity and chemical, biological, and biochemical soil properties. We did not find any significant effect of treatments on plant attributes. However, effects on soil properties were significant and more persistent with composts than with IF, especially with BC, which had higher organic C and nutrients than MC. Total soil C and N were twice as high in the BC-amended soil as in the control and IF soils. Soil extractable P was 4-fold and 2-fold higher in BC and MC-treated soils, respectively, than in the control soil, and even higher than in the IF treatment in response to BC. The highest β-glucosidase and acid phosphomonoesterase activities were found in the BC-treated soil, related to higher C and P in the soil and to higher activities of both enzymes in the biosolids compost. The highest phenol oxidase activity was found in MC and in the MC-treated soil. Potential respiration and K2SO4-extractable C were higher in the compost-treated soil, but there was no difference in microbial biomass Cbetween the compost-treated and the control soils. Despite the fact that the soil was coarse textured and a single moderate dose of compost was applied, recovery of soil chemical, microbiological, and biochemical properties was long-lasting, indicating that application of urban compost is a feasible restoration practice in this semiarid region.

Phellinus piptadeniae (Hymenochaetales: Hymenochaetaceae): taxonomy and host range of a species with disjunct distribution in South American seasonally dry forests Salvador Montoya, Carlos Alberto; Robledo, Gerardo Lucio; Cardoso, Domingos; Borba Silva, Marco A.; Fernandes, Mariana; Drechsler Santos, Elisandro Phellinus piptadeniae (Hymenochaetaceae, Hymenochaetales) is traditionally characterized by having applanate to ungulate basidiome with the pilear surface concentrically sulcate, radially cracked in old specimens, and a notorious sinuous black line in the cross section of the context. The species has been recorded in different Brazilian biomes, often associated with legume hosts and seasonally dry vegetation. It occurs highly specifically associated with Piptadenia gonoacantha in semideciduous forest of the Atlantic Forest domain at the type locality in São Paulo state, southeastern Brazil. In the Caatinga dry woodlands, northeastern Brazil, Phellinus piptadeniae occurs as host-recurrent of different Piptadenia species. During a recent polypore survey in different remnants of southeastern Atlantic Forest, specimens with the same morphology of the type were collected and the same host (P. gonoacantha) was confirmed. Morphologically similar specimens newly collected in seasonally dry tropical forests of northwestern Peru were also recorded on legume hosts (Libidibia glabrata and Pithecellobium excelsum). In this paper we discuss the morphological variation, host range, and distribution of Phellinus piptadeniae in the context of the historical biogeography of the neotropical Seasonally Dry Tropical Forest (SDTF) biome. Some putative taxonomic implications that should be further investigated in a molecular phylogenetic framework are also addressed.

Native fish larvae take advantage of introduced mussel larvae: field evidence of feeding preferences on veligers of the introduced freshwater bivalve Limnopernafortunei Paolucci, Esteban Marcelo; Almada, Pablo; Cataldo, Daniel Hugo; Boltovskoy, Demetrio Previous work has shown that the invasive bivalve Limnoperna fortunei has had a measurable impact on local food webs, but knowledge of the trophic interactions involved is still very limited. On the basis of samples collected along the lower Paraguay-middle Parana´ rivers, we studied the feeding behavior and selectivity of larval fish, with emphasis on veligers of the introduced bivalve L. fortunei. Among feeding larvae (i.e., without a yolk sac), 16.5% had only Limnoperna veligers in their guts, while 15.6% had veligers and some other prey. Half of the fish taxa recorded (8 out of a total of 16) consumed Limnoperna veligers. The Paraguay and Parana´ rivers differed strongly in the proportions of fish larvae that consumed veligers: 14 and 68%, respectively. This difference paralleled the availability of veligers in the water column, which was significantly lower in the Paraguay (0.8 ± 0.5 ind. l-1 ) than in the Parana´ River (5.5 ± 2.3 ind. l-1 ). Conversely, cladocerans, originally the staple food of fish larvae, were more abundant in the Paraguay (consumed by 48% of the individuals) than in the Parana´ River (26%). These results indicate that, when widely available, Limnoperna veligers largely replace the original prey of fish larvae, especially in their younger stages (protolarvae).

Kerr geometry in f(T) gravity Bejarano, Cecilia Soledad; Ferraro, Rafael; Guzmán Monsalve, María José Null tetrads are shown to be a valuable tool in teleparallel theories of modified gravity. We use them to prove that Kerr geometry remains a solution for a wide family of theories of gravity.

Double ionization of helium by fast electrons with the Generalized Sturmian Functions method Ambrosio, Marcelo José; Colavecchia, Flavio Dario; Gasaneo, Gustavo; Mitnik, Dario Marcelo; Ancarani, L. U. The double ionization of helium by high energy electron impact is studied. The corresponding four-body Schrödinger equation is transformed into a set of driven equations containing successive orders in the projectile–target interaction. The first order driven equation is solved with a generalized Sturmian functions approach. The transition amplitude, extracted from the asymptotic limit of the first order solution, is equivalent to the familiar first Born approximation. Fivefold differential cross sections are calculated for (e, 3e) processes within the high incident energy and small momentum transfer regimes. The results are compared with other numerical methods, and with the only absolute experimental data available. Our cross sections agree in shape and magnitude with those of the convergent close coupling method for the (10+10) eV and (4+4) eV emission energies. To date this had not been achieved by any two different numerical schemes when solving the three–body continuum problem for the fast projectile (e, 3e) process. Though agreement with the experimental data, in particular with respect to the magnitude, is not achieved, our findings partly clarify a long standing puzzle.

Admixture and genetic relationships of Mexican Mestizos regarding Latin American and Caribbean populations based on 13 CODIS-STRs Salazar Flores, J.; Zuniga Chiquette, F.; Rubi Castellanos, R.; Álvarez Miranda, J. L.; Zetina Hérnandez, A.; Martínez Sevilla, V. M.; González Andrade, F.; Corach, Daniel; Vullo, C.; Álvarez, J. C.; Lorente, J. A.; Sánchez Diz, P.; Herrera, R. J.; Cerda Flores, R. M.; Muñoz Valle, J. F.; Rangel Villalobos, H. Short tandem repeats (STRs) of the combined DNA index system (CODIS) are probably the most employed markers for human identification purposes. STR databases generated to interpret DNA profiles are also helpful for anthropological purposes. In this work, we report admixture, population structure, and genetic relationships of Mexican Mestizos with respect to Latin American and Caribbean populations based on 13 CODIS-STRs. In addition, new STR population data were included from Tijuana, Baja California (Northwest, Mexico), which represents an interesting case of elevated genetic flow as a bordering city with the USA. Inter-population analyses included CODIS-STR data from 11 Mexican Mestizo, 12 Latin American and four Caribbean populations, in addition to European, Amerindian, and African genetic pools as ancestral references. We report allele frequencies and statistical parameters of forensic interest (PD, PE, Het, PIC, typical PI), for 15 STRs in Tijuana, Baja California. This Mexican border city was peculiar by the increase of African ancestry, and by presenting three STRs in Hardy–Weinberg disequilibrium, probably explained by recurrent gene flow. The Amerindian ancestry in Central and Southeast of Mexico was the greatest in Latin America (50.9–68.6%), only comparable with the North of Central America and Ecuador (48.8–56.4%), whereas the European ancestry was prevalent in South America (66.7–75%). The African ancestry in Mexico was the smallest (2.2–6.3%) in Latin America (≥2.6%), particularly regarding Brazil (21%), Honduras (62%), and the Caribbean (43.2–65.2%). CODIS-STRs allowed detecting significant population structure in Latin America based on greater presence of European, Amerindian, and African ancestries in Central/South America, Mexican Mestizos, and the Caribbean, respectively.

Solvable models for Kodaira surfaces Console, Sergio; Ovando, Gabriela Paola; Subils, Mauro In this work, we study families of compact spaces which are of the form G/Λk,iG/Λk,i for G the oscillator group and Λk,i

Morfosedimentología del fondo marino en el sector de entrada al estuario de Bahía blanca, Argentina.; Seafloor Morphosedimentology in the Entrance Sector of Bahía Blanca Estuary, Argentina Aliotta, Salvador; Spagnuolo, Jorge Osvaldo; Ginsberg, Silvia Susana; Minor Salvatierra, Marta Elizabeth En el amplio sistema estuarial de Bahia Blanca (provincia de Buenos Aires) existen sectores carentes de un conocimiento integral de las características morfosedimentológicas submarinas. Dentro de este contexto, en el presente trabajo se estudia el fondo marino a lo largo de la costa norte ubicada en el sector de entrada del Canal Principal del estuario de Bahía Blanca. Se realizaron relevamientos acústicos (ecosonda y sonar lateral) y muestreos de sedimentos de la superficie del fondo. Se determinó la presencia de geoformas depositacionales y erosivas. Entre las de carácter acrecional se han establecido diferentes tipos de dunas y lineaciones arenosas (sand ribbons). Entre los rasgos generados por erosión se encuentran escarpas, relativamente continuas e irregulares y afloramientos rocosos aislados. Asimismo, también se diferencian fondos de sedimentos cohesivos, tanto masivos como estratificados. Como formas antrópicas se distinguen surcos de dragado y la presencia de cañerías de oleoductos y restos metálicos. El análisis de las geoformas y los sedimentos permitió establecer que en el sector este de la franja costera estudiada, prevalece un transporte sedimentario como carga de fondo hacia la Plataforma Continental, mientras que en aguas someras del sector oeste, existe una marcada deriva de sedimentos hacia el interior del estuario. La conjunción de datos morfológicos y sedimentológicos posibilitó ampliar la caracterización de dos paleoniveles costeros, indicativos de períodos de estabilización del nivel del mar durante el último proceso transgresivo.; In the large Bahia Blanca estuarine system (province of Buenos Aires) there are sectors without a comprehensive assessment of submarine morpho-sedimentological features. Within this context, in this paper the seabed along the north coast of the entrance to the Principal channel of the estuary is studied. Acoustic surveys (echo sounder and side scan sonar) and sediments sampling were performed. The presence of depositional and erosional geoforms was determined. Among those of accretional nature have been established different types of dunes and sand ribbons. The erosive forms are scarps, relatively continuous and irregular, and rocky isolated outcrops. Also, seabed cohesive sediments, both massive and stratified, were differentiated. As anthropogenic forms furrows dredging and the presence of pipes for oil and metal debris were distinguished. The analysis of geoforms and sediments determined that in the east sector of the coastal strip studied prevails sediment transport as bedload towards the Continental Shelf, while in shallow waters of the western sector, there is a marked litoral drift towards the inside of estuary. The conjunction of morphological and sedimentological data allowed to extend the characterization of two ancient coastal levels, indicative of stabilization periods of sea level during the last transgressive process.

Persistent effect of organic matter pulse on a sandy soil of semiarid Patagonia Gonzalez Polo, Marina; Kowaljow, Esteban; Castán, Elisa; Sauzet, Ophelie; Mazzarino, Maria Julia Studies of degraded semiarid regions have shown that organic residue addition is a sound restoration alternative. We examined the effects of a single dose (40 Mg ha−1) of biosolids compost (BC) and compost of the organic fraction of municipal solid waste (MC) 6 years after they were applied to a sandy soil of NW Patagonia. Results were compared with those of inorganic fertilization (IF, 100 kg N + 35 kg P ha−1) treatment and of unamended control. We measured plant cover, biomass, and diversity and chemical, biological, and biochemical soil properties. We did not find any significant effect of treatments on plant attributes. However, effects on soil properties were significant and more persistent with composts than with IF, especially with BC, which had higher organic C and nutrients than MC. Total soil C and N were twice as high in the BC-amended soil as in the control and IF soils. Soil extractable P was 4-fold and 2-fold higher in BC- and MC-treated soils, respectively, than in the control soil, and even higher than in the IF treatment in response to BC. The highest β-glucosidase and acid phosphomonoesterase activities were found in the BC-treated soil, related to higher C and P in the soil and to higher activities of both enzymes in the biosolids compost. The highest phenol oxidase activity was found in MC and in the MC-treated soil. Potential respiration and K2SO4-extractable C were higher in the compost-treated soil, but there was no difference in microbial biomass C between the compost-treated and the control soils. Despite the fact that the soil was coarse textured and a single moderate dose of compost was applied, recovery of soil chemical, microbiological, and biochemical properties was long-lasting, indicating that application of urban compost is a feasible restoration practice in this semiarid region.

Ag nanoparticles formed by femtosecond pulse laser ablation in water: self assembled fractal structures Santillán, Jesica María José; Fernandez Van Raap, Marcela Beatriz; Mendoza Zélis, Pedro; Coral, Diego Fernando; Muraca, Diego; Schinca, Daniel Carlos; Scaffardi, Lucia Beatriz We report for the first time on the formation of self-assembled fractals of spherical Ag nanoparticles (Nps) fabricated by femtosecond pulse laser ablation of a solid silver target in water. Fractal structures grew both in two and three Euclidean dimensions (d). Ramified-fractal assemblies of 2 nm height and 5–14 μm large, decorated with Ag Nps of 3 nm size, were obtained in a 2d geometry when highly diluted drops of colloidal suspension were dried at a fast heating rate over a mica substrate. When less-diluted drops were dried at slow heating rate, isolated single Nps or rosette-like structures were formed. Fractal aggregates about 31 nm size in 3d geometry were observed in the as-prepared colloidal suspension. Electron diffraction and optical extinction spectroscopy (OES) analyses performed on the samples confirmed the presence of Ag and Ag2O. The analysis of the optical extinction spectrum, using the electrostatic approximation of Mie theory for small spheres, showed the existence of Ag bare core, Ag–Ag2O and air–Ag core–shell Nps, Ag–Ag2O being the most frequent type [69 % relative abundance (r.a.)]. Core-size and shell-thickness distribution was derived from OES. In situ scattering measurements of the Ag colloidal suspension, carried out by small-angle X-ray scattering, indicate a mass fractal composed of packaged 〈DSAXS〉 = (5 ± 1) nm particles and fractal dimension df = 2.5. Ex situ atomic force microscopy imaging displayed well-ramified structures, which, analyzed with box-counting method, yield a fractal dimension df = 1.67. The growing behavior of these 2d and 3d self-assembled fractals is consistent with the diffusion-limited aggregation model.

Evaluation of the antibacterial effects of vancomycin hydrochloride released from agar-gelatin-bioactive glass composites Rivadeneira, Josefina; Di Virgilio, Ana Laura; Audisio, Marcela Carina; Boccaccini, Aldo R.; Gorustovich Alonso, Alejandro Adrian The aim of this work was to evaluate the perfomance of agar-gelatin (AG) composites and AG-containing 45S5 bioactive glass (BG) microparticles (AGBG) in relation to their water uptake capacity, sustained release of a drug over time, and antibacterial effects. The composites were fabricated by the gel-casting method. To impart the local drug release capacity, vancomycin hydrochloride (VC) was loaded in the composites in concentrations of 0.5 and 1 mg ml(-1). VC release was assessed in distilled water at 37 °C up to 72 h and quantified spectrophotometrically. The antibacterial activity of composites was evaluated by the inhibition zone test and the plate count method. The experiments were performed in vitro up to 48 h on three staphylococcus strains: Staphylococcus aureus ATCC29213, S. aureus ATCC6538 and Staphylococcus epidermidis ATCC12228. The results showed that the addition of BG to AG composites did not affect the degree of water uptake. The release of VC was significantly affected by the presence of BG. VC release was higher from AGBGVC films than from AGVC ones over prolonged incubation times. Bacterial inhibition zones were found around the composites. The halos were larger when the cells were put in contact with AGVC composites than when they were put in contact with AGBGVC ones. Nevertheless, the viable count method demonstrated that the composites inhibited Staphylococcus cell growth with no statistical differences. In conclusion, the addition of BG did not reflect an improvement in the parameters studied. On the other hand, composites loaded with VC would have a role in prophylaxis against bacterial infection.

Iron-alumina synergy in the heterogeneous Fenton-type peroxidation of phenol solutions Di Luca, Carla; Ivorra, Fernando Daniel; Massa, Paola Andrea; Fenoglio, Rosa Juana Highly dispersed Fe2O3/Al2O3 catalysts (0.5–4 wt% Fe) were prepared by incipient wetness impregnation of iron citrate over a mesoporous alumina host. Their structural and textural properties were determined by N2 adsorption–desorption at −196 °C, XRD, TEM, SEM–EDAX, Raman and XPS. The structure of the catalytic materials resulted similar to the γ-Al2O3 support, exhibiting high dispersion levels of the iron oxide active phase with a narrow pore size distribution in the range of 2–7 nm and high surface areas. The capability of these systems as efficient and active Fenton-like catalysts, were further tested for the catalytic oxidation of concentrated phenol solutions (5 g/L) with H2O2 at 70 °C in a batch reactor. The effects of iron concentration, catalyst concentration and the nature of the support were evaluated, under adjusted sub-stoichiometric oxidant concentration. Besides the positive impact of increasing the iron loading, a synergistic effect between Fe and Al species would be possibly responsible of the improvements observed using higher iron dispersions and/or support concentrations. The catalytic performance of these alumina-based catalysts resulted very promissory as they yielded: total phenol abatement, high mineralization levels (up to a maximum of 80%) and high oxidant consumption efficiencies (between 80% and 96%).