Home range size and overlap in Liolaemus multimaculatus (Squamata: Liolamidae) in pampean coastal dunes of Argentina Kacoliris, Federico Pablo; Williams, Jorge Daniel; Ruiz de Arcaute, Celeste; Cassino, Carla Corina The home range is the space used by individuals to carry out their life cycles. The Sand dune lizard (Liolaemus multimaculatus) is a vulnerable species, endemic to the pampas coasts of Buenos Aires and Río Negro Provinces in Argentina. The aim of this work was to assess home range size and overlap of the Sand dune lizard. The study was carried out at Mar Chiquita Provincial Reserve. Home range and overlap were calculated using the minimum convex polygon method. The mean ± SD home range size for all individuals was 45.90 ± 74.37 m2 and no differences were observed between males and females (p = 0.49). However, an analysis without outlier individuals showed more accurate values for females (21.31 ± 17.59 m2) and males (33.52 ± 24.62 m2), and differences between sex were observed (p = 0.04). The relationship between body size and home range size was not significant (p = 0.41). Home range overlap was high (22 to 58%; Fig. 2) and did not show differences between males and females (p > 0.05 in all cases). Our results showed some similarities with the Brazilian sand lizard (Liolaemus lutzae) in which home range value is only up to 1.5 units higher than in L. multimaculatus. Further studies about this species? social system are necessary to understand the observed patterns.

Mechanical properties of polypropylene/clay nanocomposites: Effect of clay content, polymer/clay compatibility, and processing conditions Tarapow, J. A.; Bernal, Celina Raquel; Alvarez, Vera Alejandra In this work, polypropylene/clay nanocomposites with 0.5, 1, 3, and 5 wt % of montmorillonite (MMT) (unmodified clay) were prepared by intensive mixing at 50 rpm and 10 min of mixing. For the highest clay content (5 wt %), the initial materials or the processing conditions were changed to study their independent effect. On one hand, 10 wt % of PP‐graft‐MA (PP‐g‐MA) was incorporated or MMT was replaced by organomodified clays (C10A and C30B). On the other side, for the initial system, the speed of rotation (100 and 150 rpm) and the mixing time (5 and 15 min) were altered. In all cases, the state of the clay inside the matrix (DRX), the degree of dispersion in the micro (SEM) and nano (TEM) scales, and the rheological and mechanical properties were analyzed. It was found that the stiffness increased with clay content, whereas tensile and impact strength did not significantly change. Although intercalated structures were observed in the composites with unmodified clay, in the composites with modified clay or PP‐g‐MA, improved dispersion of clay in PP was found. The mechanical properties increased accordingly. The degree of dispersion of the filler in the matrix appeared to be unaffected by the changes in the processing conditions introduced. Finally, the elastic modulus was modeled by using an effective filler‐parameter model based on Halpin–Tsai equations, which also allowed estimating the relative degree of dispersion.

4'-[2-(2-Ethoxy-ethoxy)eth-oxy]-bi-phenyl-4-carboxylic acid: Correlation between its crystalline and smectic phases Montani, Rosana Silvia; Garay, Raúl Oscar; Cukiernik, Fabio Daniel; Garland, Maria T.; Baggio, Ricardo Fortunato The crystal structure of the dimeric title compound, C19H 22O5H, is dominated by a head-to-head hydrogen-bonding inter-action between centrosymmetrically related carboxyl groups in each monomer. The result is a dimeric axis of unusual length (ca 34 Å), but still shorter than what could be expected for a fully extended chain, owing to two turning points in the oligo-eth-oxy ends. This allows for an explanation of the structure of the smectic mesophase exhibited by this compound and at the same time fully validates former geometric estimations based on PM3 calculations. © 2009 International Union of Crystallography.

Elimination of dyes from aqueous solutions using iron oxides and chitosan as adsorbents: a comparative study Pirillo, Silvina; Pedroni, Viviana Isabel; Rueda, Elsa Haydee; Ferreira, María Luján This work investigates the adsorption of Alizarin, Eriochrome Blue Black R and Fluorescein using chitosan, goethite and magnetite as adsorbents. For Alizarin, the best adsorbent is chitosan with a Langmuir parameter of 15.8 mmol dye/g adsorbent. For Eriochrome Blue Black R only 1.94 mmol dye/g chitosan is adsorbed. Langmuir parameters for the Alizarin adsorption on both iron oxides display one or two orders of magnitude lower than for chitosan and two orders of magnitude lower in the case of Eriochrome Blue Black R. Fluorescein does not adsorb in appreciable amounts on chitosan and it presents the lower affinity on the iron oxides.

Effect of blanching on drying kinetics of quince pomace undergoing conventional hot air and low-pressure superheated steam drying Brown, Valeria Anahi; Genovese, Diego Bautista; Lozano, Jorge Enrique The process of extracting fruit pectin includes the drying of pomace to prevent enzymatic destruction. It is known that best quality pectin is obtained from pomace dried at low temperature. Moreover, blanching and reduction in oxygen content as that condition obtained by low-pressure superheated steam drying (LPSSD), reduce pectin color. Last improve is obtained by inhibition of enzymatic reactions. The main objective of this work was to determine the effect of blanching on drying kinetics of quince pomace undergoing conventional hot air and LPSSD drying, a method recognized as less aggressive. Quince pomace drying was conducted to final to initial water content ratio (X/X o)< 0.07, where X is the water content. Drying curves were fitted to Page model. Results show statistical differences between drying methods; however, differences in kinetics were not found among treatments (blanching or not). As a conclusion, blanching of quince pomace did not affected drying kinetics, and both assayed methods of drying (conventional and LPSSD) required the same time to reach the same final water content. Therefore, pomace drying method should be selected by preferentially considering pectin quality and energy consumption.

Isolation of UV-B resistant bacteria from two high altitude Andean lakes (4,400 m) with saline and non saline conditions Flores, María Regina; Ordoñez, Omar Federico; Maldonado, Marcos Javier; Farias, Maria Eugenia Laguna (L.) Negra and L. Verde are high altitude Andean lakes located at the 4,400 m altitude in the Andean desert (Puna) in the Argentine northwest. Both lakes are exposed to extreme weather conditions but differ in salinity contents (salinity 6.7% for L. Negra and 0.27% for L. Verde). The aim of this work was to isolate ultraviolet B fraction (UV-B) resistant bacteria under UV-stress in order to determine, a possible connection, between resistance to UV-B and tolerance to salinity. DNA damage was determined by measuring CPDs accumulation. Connection among pigmentation production and UV resistance was also studied. Water samples were exposed to artificial UV-B radiation for 24 h. Water aliquots were plated along the exposition on different media, with different salinity and carbon source content (Lake medium (LM) done with the lake water plus agar and LB). CFU were counted and DNA damage accumulation was determined. Isolated bacteria were identified by 16S rDNA sequence. Their salinity tolerance, were measured at 1, 5 and 10% NaCl and their pigment production in both media was determined. In general it was found that UV resistance and pigment production were the optimum in Lake Medium done with lake water which maintained similar salinity. The most resistant bacteria in L. Negra were different strains of Exiguobacterium sp. and, in L. Verde, Staphylococcus sp. and Stenotrophomonas maltophilia. These bacteria showed the production and increase of UV-Vis absorbing compounds under UV stress and in LM. Bacterial communities from both lakes were well adapted to high UV-B exposure under the experimental conditions, and in many cases UV-B even stimulated growth. The idea that resistance to UV-B could be related to adaptation to high salinity is still an open question that has to be answered with future experiments.

La lucha de Kraft-Terrabusi: Comisiones Internas, izquierda clasista y “vacancia” de representación sindical; The Kraft-Terrabusi struggle: Workers organization, clasist left and union representation “vacancy” Varela, Paula; Lotito, Diego En este artículo, intentaremos un primer análisis del caso Kraft Foods desarrollando, en primer lugar, una reconstrucción de la historia reciente de la organización obrera en la empresa y, en segundo término, un análisis de un elemento que el conflicto puso sobre la mesa del debate político y conceptual: la relación entre la revitalización de la organización sindical en el lugar de trabajo, la izquierda clasista y los denominados problemas de representatividad de las cúpulas sindicales en Argentina. El abordaje de este elemento pretende, también, abrir nuevos interrogantes sobre las contradicciones y potencialidades inscriptas en la irrupción de la clase obrera en la escena política nacional, en el marco del fin de ciclo kirchnerista.; In this article, we will attempt a first analysis of the Kraft Foods case developing, in first place, a reconstruction of the recent history of labor organization in the company and, secondly, an essential element to understand what the conflict brought to the actual conceptual and political debate: the relationship between the revitalization of the union organization in the workplace, the clasist left and the so-called problems of representativeness of the union leaderships in Argentina. The approach to this element also intends to open new questions about the contradictions and potentialities inscribed in the emergence of the working class in the national political scene, as part of the end of the Kirchner political cycle.

Paleontología del Chaco Oriental. Una nueva localidad con mamíferos fósiles pleistocenos del río Bermejo (Formosa, Argentina); Paleontology of the Chaco Oriental. A new fossiliferous locality with Pleistocene fossil mammals in the Bermejo river (Formosa, Argentina) Zurita, Alfredo Eduardo; Miño Boilini, Ángel Ramón; Carlini, Alfredo Armando; Iriondo, Martin Horacio; Alcaraz, María Alejandra Los sedimentos loéssicos y palustres del Pleistoceno tardío-Holoceno temprano (ca. 130-8 ka) de la Argentina preservan uno de los registros más completos de vertebrados (principalmente mamíferos) de América del Sur. Sin embargo, no todas las áreas con esos sedimentos han recibido la misma atención, y en particular, aquellas del centro-norte y noroeste de Argentina (29º S-21º S), fueron las menos tratadas. Aquí damos a conocer una asociación de mamíferos pleistocenos provenientes del sector central del Chaco Oriental, que constituye el registro más completo para la provincia de Formosa, Argentina. Esta fauna fue exhumada de las barrancas del río Bermejo, en cercanías a la localidad de Villa Escolar, y los sedimentos son tentativamente referidos a la Formación Fortín Tres Pozos (Pleistoceno superior). El conjunto de mamíferos reconocidos está constituido por elementos ?pampeano-patagónicos: Cingulata: Glyptodon sp., Neosclerocalyptus cf. N. paskoensis, Pampatherium typum; Phyllophaga: Megatherium sp.; Artiodactyla: cf. Morenelaphus, cf. Hemiauchenia paradoxa; y Notoungulata: Toxodon sp. La presencia de Neosclerocalyptus cf. N. paskoensis sugiere una edad Lujanense (Pleistoceno tardío-Holoceno temprano), en tanto que recientes dataciones por luminiscencia estimulada ópticamente (OSL) efectuadas en sedimentos de la Formación Fortín Tres Pozos indican una edad aproximada 58,160 años AP (±4390). Esta asociación de mamíferos (más aquellos previamente conocidos para el sur y centro del Chaco Oriental) son taxones adaptados a ambientes abiertos y relativamente fríos, lo que resulta congruente con las condiciones de depositación de los sedimentos que componen el abanico aluvial del río Bermejo. En gran parte, este conjunto faunístico sería sincrónico con el Estadio Isotópico 3 (59-28 ka) y probablemente se relacione con algunas de las fases frías y semiáridas detectadas en este lapso.; The palustrian and loessic sediments of the late Pleistocene-early Holocene (ca. 130–8 ka) of Argentina contain and preserve one of the most important records of vertebrates (mainly mammals) of South America. However, except for the Pampean region of Argentina, largely studied from the middle the 19th century, other areas, especially those located between 29ºS and 21ºS are, from a palaeontological point of view, very poorly known. In this contribution an association of Pleistocene mammals is reported, coming from the center area of the Chaco Oriental, which in addition constitutes the most complete record for the Formosa province, Argentina. This association was exhumed from the cliff of the Bermejo river, near the locality of Villa Escolar, and probably corresponds to the Fortín Tres Pozos Formation (Upper Pleistocene). This ensemble of fossil mammals is represented by the following taxa: Cingulata: Glyptodon sp., Neosclerocalyptus cf. N. paskoensis, Pampatherium typum; Phyllophaga: Megatherium sp.; Artiodactyla: cf. Morenelaphus, cf. Hemiauchenia paradoxa; Notoungulata: Toxodon sp. In this context, the presence of the Glyptodontidae Neosclerocalyptus cf. N. paskoensis suggests a Lujanian age (late Pleistocene-early Holocene), while recent optically stimulated luminescence (OSL) dating in the sediments of the Fortin Tres Pozos Formation indicate an approximate age of 58,160 years BP (± 4390). This set of mammals (plus those previously published for this region) are constituted by taxa adapted to cold and arid/semiarid environmental conditions, which is consistent with the inferred conditions of the deposition of sediments that forms the alluvial fan of the Bermejo river. Much of this fauna would be synchronous with the Isotope Stage 3 (59–28 ka) and probably relates to some of the cold and arid phases detected in this period.

The Scelidotheriinae Ameghino, 1904 (Phyllophaga, Xenarthra) from the Ensenadan-Lujanian Stage/Ages (Early Pleistocene to Early-Middle Pleistocene-Early Holocene) of Argentina Miño Boilini, Ángel Ramón; Carlini, Alfredo Armando Review of the specimens assigned to Scelidotheriinae (Phyllophaga, Xenarthra) from the Ensenadan-Lujanian Stage/Ages of Argentina, showed that two genera are recognized for this territory: Scelidotherium (Owen) and Scelidodon (Ameghino), with the following species: Scelidotherium bravardi (Lydekker), for the Ensenadan Stage/Age (Early Pleistocene to Early-Middle Pleistocene), restricted to Buenos Aires Province, and the Pleistocene of San Luis Province; Scelidotherium leptocephalum (Owen), for the Bonaerian-Lujanian Stage/Ages (Middle Pleistocene-Early Holocene), of the Buenos Aires Province, in the Lujanian Stage/Age of Salta and Córdoba Provinces; Scelidotherium sp. for the Lujanian Stage/Age of Corrientes Province, Bonaerian-Lujanian Stage/Ages of Chaco Province; Scelidodon tarijensis (Gervais and Ameghino), for the Ensenadan-Bonaerian Stage/Ages of Buenos Aires Province, in Pleistocene of Córdoba Province; Scelidodon chiliense (Lydekker) for the Lujanian Stage/Age of San Luis Province, and Scelidodon sp. for the Lujanian Stage/Age of Corrientes, Buenos Aires and Entre Ríos Provinces, and the Pleistocene of Tucumán Province.

Enseñanza de la Diversidad Vegetal en la Universidad: una nueva propuesta dinámica innovadora Galetto, Leonardo; Urcelay, Roberto Carlos; Torres, Carolina Cecilia; Nattero, Julieta; Romanutti, Alejandra Aida; Scrivanti, Lidia Raquel; Anton, Ana Maria Ramona Se implementó una propuesta didáctica innovadora para la asignatura Diversidad Vegetal II, correspondiente a la Carrera de Biología de la Universidad Nacional la Universidad Nacional de Córdoba. La asignatura se desarrolló a partir de la combinación de algunos problemas y preguntas de investigación (e.g., materiales botánicos desconocidos que debieron ser caracterizados e identificados, información sobre los grupos de plantas que debió ser seleccionada y sintetizada de manera adecuada) que fueron resueltos por los alumnos, promoviéndose su participación activa en el proceso de aprendizaje. Al final del ciclo lectivo 2006 se realizó una encuesta anónima para evaluar los objetivos propuestos inicialmente y la percepción de los alumnos, y para detectar falencias en la implementación de la propuesta. La mayoría de los alumnos (78,5%) calificó como buena o muy buena la propuesta en general, y también a los trabajos prácticos (88,8%) en particular. El 85,7% de ellos consideró adecuado el modo de evaluación. El balance entre las distintas actividades fue razonable sólo para el 55,7% de los alumnos, aspecto que deberemos reconsiderar. Observamos un gran entusiasmo y motivación en los alumnos por asistir y participar en las clases, donde se sintieron estimulados para buscar información, discutirla e intentar autogestionar el conocimiento sobre plantas con la guía de los docentes.

Polycyclic aromatic hydrocarbons (PAHs) distribution in water column, native mussels (Brachydontes sp and Tagelus sp) and fish (Odontesthes sp) from an industrialized South American estuary Arias, Andres Hugo; Spetter, Carla Vanesa; Freije, Rubén Hugo; Marcovecchio, Jorge Eduardo Polycyclic aromatic hydrocarbons (PAHs), one of the major groups of anthropogenic environmental pollutants, were firstly identified and measured in coastal waters, native mussels and fish of an industrialized South American estuary. The aim of this study was to measure the PAHs concentrations and evaluate distribution and sources in surface seawater, native mussels Brachidontes sp. and Tagelus sp.) and fish (Odontesthes sp.) from various coastal sites of the Bahı´a Blanca Estuary, in order to put the estuary in a global context and assess it ecotoxicological risk. For this, 40 samples of surface water were collected between August 2004 and February 2006 and analyzed by GC/MS for 17 PAHs, including the 16 EPA priority PAHs. In addition, main physicochemical parameters, nutrients and pigments were simultaneously obtained as key parameters to evaluate possible relationships. Finally, several native mussel communities and fish specimens were also analyzed for PAHs contents. The area of study is located at the Argentinean coast and presents an intensive human and industrial activity at the north shoreline. Total PAHs (S17 PAHs) in whole surface waters ranged from undetected to more than 4 mg/l. Seasonal PAHs levels relationship with master parameters suggested a relationship between the phytoplankton microbiological cycling and the dissolved/suspended PAHs occurrence in water. In addition, Cluster Analysis was performed to identify the homogeneous groups of individual PAHs in water and Principal Component Analysis to extract underlying common factors. The result of PCA was similar to that of the cluster analysis; both could differentiate two subsets of pyrogenic sources and a petrogenic origin. PAHs levels in indigenous mussels (Brachidontes sp. and Tagelus sp.) ranged from 348 to 1597 ng/g (dry weight). Fish specimens (Odontesthes sp.) showed a mean concentration of 1095 ng/g d.w. in whole tissues. Mussel source ratios and PCA results were in good agreement with the dominant sources assessed for water samples and further enabled the linking of PAHs origins according to the sample location. The Bahı´a Blanca Estuary wide mean of the PAHs burden in mussels showed that the average PAH contamination level was within the ??moderate?? category. Levels appeared as ecotoxicologically risk safe for the inner stations; however, they were exceeding various safety criterions at the outer. Results indicate the needing of a systematic monitoring program for the area of study, in order to provide accurately assessment and management of risks for the regional population.

Xylaria berkeleyi (Xylariaceae, Ascomycota) primera cita para la República Argentina; Xylaria berkeleyi (Xylariaceae-Ascomycota) new record from the República Argentina Hladki, Adriana Ines; Romero, Andrea Irene Hladki, Adriana I. y Romero, Andrea I. 2009. Xylaria berkeleyi (Xylariaceae, Ascomycota): primera cita para la República Argentina. Lilloa 46 (1-2). Se cita a Xylaria berkeleyi por primera vez en el país. Se describen los estromas teleomórficos y las características del cultivo en agar-avena, incluyendo ilustraciones y fotografias.; Hladki, Adriana I. & Andrea I. Romero. 2009. Xylaria berkeleyi (Xylariaceae-Ascomycota) new record from the República Argentina. Lilloa 46 (1-2). Xylaria berkeleyi is described as new record from Argentina. The strain was got for the first time. It is described on oatmeal agar.

Estado actual del conocimiento de la familia Ceratopogonidae en la Patagonia (Diptera: Nematocera); Current knowledge of the family Ceratopogonidae in Patagonia (Diptera: Nematocera) Spinelli, Gustavo Ricardo; Marino, Pablo Ignacio Ceratopogonidae incluye pequeños dípteros nematoceros que crían en hábitats acuáticos o semiacuáticos. Hasta los '80, el conocimiento de su taxonomía en la Patagonia se hallaba limitado a la contribución de los comienzos de los '30 de Ingram y Macfie, sobre la base de material capturado en 1926-27, en el área del Parque Nacional Nahuel Huapi y zonas vecinas de Chile. En los últimos 25 años, se pusieron en marcha diferentes proyectos, resultando la descripción o registro de numerosos taxones para la región. Si se contabilizan los datos publicados, 102 especies habitan en la Patagonia, de las cuales 86 (84,31%) son endémicas para la región. Este alto porcentaje es evidente en los bosques de Nothofagus, con 71 especies endémicas de este bioma, nueve lo son de la estepa y seis presentan registros en bosque y estepa. Datos aún no publicados concuerdan con este esquema. Diecinueve géneros están representados en la Patagonia, diez de ellos con amplia distribución, tres de distribución transantártica y seis son endémicos para el área. Para la misma, se hallan publicadas las revisiones de Forcipomyia, Atrichopogon, Borkenthelea, Macrurohelea y Paradasyhelea; se han finalizado y aún no publicado aquellas de Dasyhelea y Palpomyia, está muy avanzada la de Stilobezzia y se prevé comenzar con las de Austrohelea, Austrosphaeromias, Physohelea y Bezzia. Se calcula que estos datos no divulgados contienen al menos 55 especies todavía no descriptas. Con respecto a los aspectos biogeográficos se pueden destacar estudios que tienden a establecer relaciones entre las áreas reconocidas en esquemas biogeográficos propuestos para la región andina.; Ceratopogonidae includes small nematoceran Diptera which breed in aquatic and semiaquatic habitats. Until the 80´s its taxonomic knowledge in Patagonia was limited to the early 30´s contribution of Ingram and Macfie, from material collected in 1926-27 in the area of the Nahuel Huapi National Park and neighboring sites of Chile. During the last 25 years several projects were performed, many new taxa were described or firstly recorded from the mentioned area. Considering the published data, 102 especies inhabit Patagonia, out of which 86 (84,31%) are endemic. This high percentage is evident in the Nothofagus forests with 71 endemic species, nine are endemic from the steppe and six occur in both biomas. Unpublished data is consistent with this squeme. Nineteen genera are represented in Patagonia, ten widely distributed, three exhibiting transantarctic distribution and six endemic of Patagonia. Revisions of Forcipomyia, Atrichopogon, Borkenthelea, Macrurohelea and Paradasyhelea for the area are published. Those of Dasyhelea and Palpomyia are finished and remain unpublished, Stilobezzia's is almost completed, and studies on Austrohelea, Austrosphaeromias, Physohelea and Bezzia will begin soon. Fifty-five undescribed species are recognized. Regarding biogeographical aspects, there are available studies aimed at establishing relationships between areas recognized in squemes of the Andean region.

A revision of the Patagonian predaceous midges of the genus Palpomyia Meigen (Diptera: Ceratopogonidae) Spinelli, Gustavo Ricardo; Grogan, William L.; Ronderos, Maria Marcela This revision of the predaceous midges in the genus Palpomyia Meigen inhabiting the Patagonian region of Argentina and Chile recognizes eight species, provides diagnoses, descriptions, illustrations and a key to all species, as well as new distributional records of previously described species. Four new species are described and illustrated: P. mapuche, P. marinoi, P. septentrionalis and P. yamana (spp. n.). Palpomyia patagonica Ingram and Macfie and P. subfuscula I. and M. are redescribed and illustrated, the previously unknown male of P. patagonica is described and illustrated, and P. subaspera (Coquillett) is recorded for the first time from Patagonia. Palpomyia chilensis Ingram & Macfie is transferred to Austrosphaeromias Spinelli (n. comb.)

Cultivos diseñados por ingeniería genética: Una alternativa atractiva para la producción de biocombustibles. Parte I Luciani, Gabriela Fabiana; Díaz, Marina; Martinez Macias, Félix; Salomón, Débora Gisele; Echenique, Carmen Viviana Hoy en día, herramientas como la ingeniería genética y el mejoramiento molecular han permitido modificar los cultivos. Los desafíos incluyen desde encontrar nuevos cultivos alternativos, capaces de reemplazar a la soja y el maíz en la producción de diésel y etanol, hasta modificar genéticamente los cultivos tradicionales para obtener mayor rendimiento o mejor calidad. La posición de nuestro país en la producción de los biocombustibles.

Cultivos diseñados por ingeniería genética: Una alternativa atractiva para la producción de biocombustibles. Parte II Luciani, Gabriela Fabiana; Díaz, Marina; Martinez Macias, Félix; Salomón, Débora Gisele; Echenique, Carmen Viviana En la producción de biocombustibles los desafíos son nuevos: la reducción de los costos de los pretratamientos que remueven la lignina, la producción de enzimas que convierten a la celulosa yhemicelulosas de la pared celular en azúcares, y la fermentación de los azúcares simples en etanol. Y en todos ellos, el denominador común es la reducción y/o modificación del contenido de lignina de la pared celular.

ROS production by endogenously generated Protoporphyrin IX in murine leukemia cells Diez, Berenice Andrea; Cordo Russo, Rosalia Ines; Teijo, Maria Julieta; Hajos, Silvia Elvira; Batlle, Alcira María del C.; Fukuda, Haydee Endogenous production of Protoporphyrin IX (Pp1X) is succesfully exploited for photodynamic therapy (PDT) on malignant cells, following 5-aminolevulinic acid (ALA) administration and light irradiation. This treatment kills cancer cells by damaging organelles and impairing metabolic pathways via cellular reactive oxygen species (ROS) generation. We studied the efficiency of Pp1X synthetized from ALA on ROS generation, in the vincristine resistant (LBR-V160), Doxorubicin resistant (LBR-D160) and sensitive (LBR-) murine leukemia cells. Cells were incubated 4hr with 1mM ALA and then irradiated during different times with flourescent light. One hour later, production of ROS was analyzed by flow cytometry using different flourescent probes: Hydroethidine (HE) for superoxide anion, 2,7 Dichlorodihydroflourescein diacetate (DCFH-DA) for hydrogen peroxide; mitochondrial damage was examined with 3,3 Dinexyloxacarbocyanine iodide (DIOC6). We found that superoxide anion production in the three cell lines increased with irradiation time whereas no peroxide hydrogen was detected. Mitochondrial damage also increased in an irradiation time dependent manner, being higher in the Vincristineresistant line. Previous studies have demonstrated that apoptotic cell death increased with irradiation time, which is consistent with these results, indicating that ROS are critical in ALA-PDT efficiency to kill malignant cells.  

A Neural Network Model for Estimating the Particle Size Distribution of Dilute Latex from Multiangle Dynamic Light Scattering Measurements Gugliotta, Luis Marcelino; Stegmayer, Georgina; Clementi, Luis Alberto; González, Verónica Doris Guadalupe; Minari, Roque Javier; Leiza, José; Vega, Jorge Ruben The particle size distribution (PSD) of dilute latex was estimated through a general regression neural network (GRNN) that was supplied with PSD average diameters derived from multiangle dynamic light scattering (MDLS) measurements. The GRNN was trained with a large set of measurements that were simulated from unimodal normal-logarithmic distributions representing the PSDs of polystyrene (PS) latexes. The proposed method was first tested through three simulated examples involving different PSD shapes, widths, and diameter ranges. Then the GRNN was employed to estimate the PSD of two PS samples; a latex standard of narrow PSD and known nominal diameter, and a latex synthesized in our laboratory. Both samples were also characterized through independent techniques (capillary hydrodynamic fractionation, transmission electron microscopy, and disc centrifugation). For comparison, all examples were solved by numerical inversion of MDLS measurements through a Tikhonov regularization technique. The PSDs estimated by the GRNN gave more accurate results than those obtained through other conventional techniques. The proposed method is a simple, effective, and robust tool for characterizing unimodal PSDs.

Reversible Ion Induced Modification of Consequent Secondary Electron Emission in Porous Silicon Ruano Sandoval, Gustavo Daniel; Ferron, Julio; Koropecki, Roberto Roman We report measurements of secondary electron emission (SEE) induced by electron and ion bombardment on porous silicon (PS). We found that electron induced emission is strongly reduced by ion bombardment, and that this reduction is reversible. The reduction effect is large even for ion fluxes much lower compared to that of the electron beam.
We attribute this effect to changes in the charge distribution of the surface dipole originated in the difference between ion and electron charge deposition depths. The nanostructure of PS plays an important role in this effect as well as in the reversibility of the process. We think that this effect could be useful in the dynamic centering and monitoring of ion and electron beams in electron spectroscopy.

Effect of anthelmintics on reproductive performance and first lactation culling rate in heifers Mejía, M. E.; Perri, Adrián Francisco; Miglierina, M. M.; Formía, N.; Becu, Damasia; Lacau, Isabel María Female Holstein calves were treated with ivermectin from birth to first oestrus to study the effect of parasitic burden and anthelmintic treatment on reproductive and productive performance. First oestrus, age at first service and age at calving were advanced by 30, 70 and 110 days, respectively (P<0·05), in ivermectin-treated animals compared with controls. No significant differences were observed in the conception rate, the number of services and the characteristics of the newborn calves and any problems at calving between the two groups. Daily milk yield, fat content in milk during first lactation, and the concentrations of growth hormone, insulin-like growth factor type 1, insulin and prolactin in serum were similar in both groups of cows. Culling during the first lactation was more common in untreated (47 per cent) than in treated (11 per cent) cows (P<0·05).