Ciencia y Tecnología
Methanol/air fuel cells: catalytic aspects and experimental diagnostics
García, M. F.; Sieben, Juan Manuel; Pilla, A. S.; Duarte, Marta María Elena; Mayer, Carlos Enrique
Methanol/air fuel cell with direct feed of methanol has received growing attention due to the possibility of using a liquid fuel of simple storing. This work comments studies on the preparation of PtRu catalysts for methanol oxidation and on the influence of different operative parameter on the performance of a lab scale fuel cell. The best conditions for PtRu catalysts preparation using metal electrodeposition techniques were found. Different carbon materials were used, such as glassy carbon, carbon paper and graphite fiber cloths and felts . The more active materials were found to be graphite felts after being preoxidized electrochemically to obtain a higher surface oxide concentration. Acceptable performance of the fuel cell was obtained working at 90 {ring operator} C and low methanol concentration, because in these conditions the potential, the transport process rates and the electrode reaction kinetics increase.
Upper Cambrian carbonate sequences of the Argentine Precordillera and the Steptoean C-Isotope positive excursion (SPICE)
Upper Cambrian carbonate sequences of the Argentine Precordillera and the Steptoean C-Isotope positive excursion (SPICE)
Sial, A. N.; Peralta, Silvio Heriberto; Ferreira, V. P.; Toselli, Alejandro Jose; Aceñolaza, Florencio Gilberto; Parada Reyes, Miguel Angel; Gaucher, C.; Alonso, Ricardo Narciso; Pimentel, Marcio
Carbon and Sr-isotope profiles in Upper Cambrian platformal carbonate Formations in the Precordillera, western Argentina (Zonda, La Flecha and La Silla Formations), were constructed for three representative sections: (a) Quebrada de la Flecha, Eastern Precordillera, (b) Cerro La Silla, Central Precordillera and (c) Quebrada de La Angostura, northern part of the Central Precordillera. At Quebrada de La Angostura, upper part of the La Flecha Formation, δ13Ccarb varies continuously up-section from - 2.0 to + 5.6‰ (PDB) and records the SPICE anomaly (+ 5‰) reported for the first time in South America. The peak of this excursion is characterized by intercalated 2 m thick beds of black shale with marl and limestone that record the onset of a sea-level change. The Steptoean Zonda Formation dolomites at the Quebrada de la Flecha exhibit a total δ13C range from - 2.7 to + 0.6‰ with discrete positive anomaly about 200 m from the transition to the overlying Sunwaptan La Flecha Formation. Pronounced C-isotope anomaly (- 5.6‰) is observed in the La Flecha Formation at about 300 m below the transition to the La Silla Formation. At the Cerro La Silla section, the Zonda Formation exhibit δ13C values of ∼ - 1‰, increasing slightly at the transition to the La Flecha Formation (- 1 to 0‰). The transition of the La Flecha to the La Silla Formations is characterized by alternation of black shales and dolomitic limestone with a discrete positive C-isotope excursion, probably corresponding to the SPICE. At the Quebrada de La Flecha, 87Sr/86Sr for the Zonda Formation varies from 0.70924 to 0.70955 and for the La Flecha Formation from 0.70908 to 0.70942. At Cerro La Silla this ratio varies from 0.70914 to 0.70923 for the La Flecha Formation, and from 0.70898 to 0.70980 for the La Silla Formation. At the Quebrada de La Angostura, ratios for the La Flecha carbonates range from 0.70918 to 0.70993. The overall variation of 87Sr/86Sr is consistent with globally reported Upper Cambrian seawater values at ca. 500 Ma. The unambiguous record of SPICE in the La Flecha Formation at the Quebrada de La Angostura supports a Steptoean age for its deposition and allows precise local, regional, and global stratigraphic correlation. The pronounced negative C-isotope excursion recorded in the La Flecha Formation carbonates at the Quebrada de La Flecha is likely equivalent to that registered in Sunwaptan carbonates of North America and Australia, and might be tied to a global event, as a valuable tool in stratigraphic correlation (SNICE, acronym for Sunwaptan negative isotope carbon excursion).
An efficient biotransformation of dialkyl esters of 2-oxoglutaric acid by Rhodotorula minuta whole cells
An efficient biotransformation of dialkyl esters of 2-oxoglutaric acid by Rhodotorula minuta whole cells
Rustoy, Eduardo Miguel; Cerrutti, Patricia; Galvagno, Miguel Angel; Baldessari, Alicia
Whole cells of the yeast Rhodotorula minuta were used in the biotransformation of dialkyl esters of 2-oxoglutaric acid. Almost 100% of conversion with 97-98% of enantiomeric excess of the (S) form of 2-hydroxydiesters was obtained through an enantioselective reduction of dimethyl and diethyl 2-oxoglutarate. When longer alkoxy chain 2-oxoglutarates were used as substrates, the corresponding 4-hydroxybutyric esters were obtained, suggesting a combination process including hydrolysis, decarboxylation and reduction. The cells showed a remarkable high productivity: high conversion and enantiomeric excess were obtained at 2 g wet weight mmol-1 substrate.
A Bayesian deconvolution strategy for immunoprecipitation-based DNA methylome analysis
A Bayesian deconvolution strategy for immunoprecipitation-based DNA methylome analysis
Down, Thomas A.; Rakyan, Vardhman K.; Turner, Daniel J.; Flicek, Paul; Li, Heng; Kulesha, Eugene; Gräf, Stefan; Johnson, Nathan; Herrero, Javier; Tomazou, Eleni M.; Thorne, Natalie P.; Bäckdahl, Liselotte; Herberth, Marlis; Howe, Kevin L.; Jackson, David K.; Miretti, Marcos Mateo; Marioni, John C.; Birney, Ewan; Hubbard, Tim J. P.; Durbin, Richard; Tavaré, Simon; Beck, Stephan G.
DNA methylation is an indispensible epigenetic modification required for regulating the expression of mammalian genomes. Immunoprecipitation-based methods for DNA methylome analysis are rapidly shifting the bottleneck in this field from data generation to data analysis, necessitating the development of better analytical tools. In particular, an inability to estimate absolute methylation levels remains a major analytical difficulty associated with immunoprecipitation-based DNA methylation profiling. To address this issue, we developed a cross-platform algorithm - Bayesian tool for methylation analysis (Batman) - for analyzing methylated DNA immunoprecipitation (MeDIP) profiles generated using oligonucleotide arrays (MeDIP-chip) or next-generation sequencing (MeDIP-seq). We developed the latter approach to provide a high-resolution whole-genome DNA methylation profile (DNA methylome) of a mammalian genome. Strong correlation of our data, obtained using mature human spermatozoa, with those obtained using bisulfite sequencing suggest that combining MeDIP-seq or MeDIP-chip with Batman provides a robust, quantitative and cost-effective functional genomic strategy for elucidating the function of DNA methylation. © 2008 Nature Publishing Group.
Intrinsic Kinetic Modeling with Explicit Radiation Absorption Effects of the Photocatalytic Oxidation of Cyanide with TiO2 and Silica-Supported TiO2 Suspensions
Intrinsic Kinetic Modeling with Explicit Radiation Absorption Effects of the Photocatalytic Oxidation of Cyanide with TiO2 and Silica-Supported TiO2 Suspensions
Marugan, Javier; Van Grieken, Rafael; Cassano, Alberto Enrique; Alfano, Orlando Mario
This study is focused on the kineticmodeling of the photocatalytic oxidation of cyanide in slurry reactors. The developed model is based on an accepted reaction mechanism and explicitly takes into account the differences in the local volumetric rate of photon absorption (LVRPA) produced by the unavoidable radiation profiles existing in the photoreactor. The model and its correspondent procedures for the evaluation of the LVRPA distribution, and the estimation of the kinetic parameters have been successfully validated with both powder TiO2 and TiO2/SiO2 photocatalysts with improved recovery properties. In both cases, the model reproduces the influence of the catalyst loading, the initial cyanide concentration, and the inlet radiation flux on the reaction rate, with errors below 5%. The kinetic parameters estimated for the model are independent of the irradiation form, as well as the reactor size and its geometrical configuration, providing the necessary information for scaling-up and designing commercial scale photoreactors.
PI3K/Akt inhibition modulates multidrug resistance and activates NF-κB in murine lymphoma cell lines
PI3K/Akt inhibition modulates multidrug resistance and activates NF-κB in murine lymphoma cell lines
García, Mariana Gabriela; Alaniz, Laura Daniela; Cordo Russo, Rosalia Ines; Alvarez, Elida Ester; Hajos, Silvia Elvira
Upregulation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway has been described in some tumors related to multidrug resistance (MDR). The aim of this work was to analyze the relationship between PI3K/Akt, MDR and NF-kappaB in murine lymphoma cell lines resistant to vincristine (LBR-V160) and doxorubicin (LBR-D160) as well as in the sensitive line (LBR-). PI3K/Akt activity, analyzed by phosphatidylinositol trisphosphate production and phosphorylated Akt (p-Akt) expression, was higher in the resistant cell lines than in the sensitive one and inhibition with wortmannin or LY294002 improved apoptosis in the resistant cell lines. Vincristine but not doxorubicin increased p-Akt expression whereas co-treatment with PI3K inhibitors and vincristine increased apoptosis in the three cell lines. Wortmannin and LY294002 inhibited P-glycoprotein (Pgp) function and also increased NF-kappaB activity. We concluded that the PI3K/Akt pathway is involved in MDR in lymphoma cell lines and PI3K/Akt inhibition correlates down-regulation of NF-kappaB activity and inhibition Pgp function.
Carbon steel passivity examined in alkaline solutions: the effect of chloride and nitrite ions
Carbon steel passivity examined in alkaline solutions: the effect of chloride and nitrite ions
Valcarce, María Beatriz; Vazquez, Marcela Vivian
The effect of chloride and nitrite ions on the passivity of steel in alkaline solutions was investigated. Four nitrite dosages were tested, resulting in various nitrite/chloride ratios. The behavior of steel was evaluated on electrodes aged during 1 and 90 days, measuring electrochemical parameters such as the corrosion, pitting and repassivation potentials, the corrosion current density, the weight loss and performing electrochemical impedance spectra. The presence of 0.8 mol l-1 of chloride induced pitting only under polarization and when the chloride/hydroxyl ratio was not less than one. Nitrite ions behave as effective inhibitors of pit propagation for all the concentrations tested (0.2-0.8 mol l-1). A nitrite/chloride ratio of 0.25 induces complete surface repassivation. Nevertheless, at open circuit potential, the high alkalinity guarantees passivation even in the presence of chlorides. In the event that the passive layer is damaged and pitting can be initiated, nitrite ions are effective in inhibiting pit propagation. © 2008 Elsevier Ltd. All rights reserved.
An anilioid snake from the Upper Cretaceous of northern Patagonia
An anilioid snake from the Upper Cretaceous of northern Patagonia
Gomez, Raul Orencio; Baez, Ana Maria; Rougier, Guillermo W.
We report the first record of anilioids from southern South America, a region where they do not live today. The fossils come from the Allen Formation (Late Campanian Early Maastrichtian) at Bajo Trapalcó and Bajo de Santa Rosa localities, Río Negro province, Argentina. The remains consist of several vertebrae, most of which belong to the mid posterior precloacal region of the column. Comparisons to other extant and extinct anilioid taxa indicate that these remains represent a new taxon, Australophis anilioides gen. et sp. nov. Australophis is morphologically closer to Palaeocene Hoffstetterella from Brazil and extant South American Anilius than to any other snake. These taxa might be closely related, in which case they would represent a lineage distinct from that including Cylindrophis and uropeltids. The two lineages must have diverged by the Late Cretaceous.
Entomofauna asociada al molle (Schinus areira L.) en la Quebrada de Humahuaca, Jujuy, Argentina
Entomofauna asociada al molle (Schinus areira L.) en la Quebrada de Humahuaca, Jujuy, Argentina; Entomofauna associated to the Peppertree (Schinus areira L.) in Quebrada de Humahuaca, Jujuy, Argentina
Neder, Lilia Estela; Zamar, María Inés; Ortiz, Felix; Montero, Teresa Eleonor; Linares, Mario Alfredo; Hamity, Verónica Cecilia; Quispe, Rosa del Valle
El molle, Schinus areira (Anacardiaceae), es una especie importante para los pobladores por sus múltiples aplicaciones. La falta de conocimiento sobre factores bióticos que pudieran incidir en la sanidad de este recurso motivó la realización del presente trabajo, cuyos objetivos fueron: identificar y evaluar la presencia, rol trófico y abundancia de los insectos asociados a S. areira en la Quebrada de Humahuca, Jujuy. Se realizaron 8 muestreos estacionales en cinco localidades de la Quebrada de Humahuaca. Cada muestra aleatoria consistió de 10 ramas de 20 cm, provenientes de 10 plantas de S. areira, llevándose un registro de la presencia y abundancia de las especies, en relación al estado fenológico del molle. Se recolectaron 679 ejemplares: Hemiptera (396), Lepidoptera (122), Thysanoptera (104), Hymenoptera (34), Diptera (13), Coleoptera (9) y Neuroptera (1). Las especies más relevantes en términos de abundancia, distribución y grado de daño que ocasionan al follaje de la planta fueron: Calophya schini Tuthill (Hemiptera), especie cecidógena de hojas, y la defoliadora Tolype guentheri (Lepidoptera). Las antófilas estuvieron representadas por Thysanoptera: Thrips tabaci, Frankliniella australis, F. gemina, F. occidentalis y F. valdiviana. Los frutos son atacados por Megastigmus sp. (Hymenoptera) y Lithraeus sp. (Coleoptera). Entre las benéficas se destaca el parasitoide de T. guentheri: Horismenus sp., (Hymenoptera). Entre los predadores de trips, pulgones y cochinillas se registraron especies de Anthocoridae (Hemiptera), Hyperaspis sp. (Coleoptera: Coccinellidae) y Hemerobiidae (Neuroptera).; The Pepper tree, Schinus areira (Anacardiaceae), is a valuable species to native inhabitants because of its multiple applications. The lack of knowledge on biotic factors that could affect the health of this resource motivated the present study. The objectives were: to identi fy and evaluate the presence, trophic role and abundance of the insects associated with S. areira in Quebrada de Humahuaca, Jujuy. Eight seasonal samples were carried out at five localities in Quebrada de Humahuaca. Each random sample consisted of 10 twenty-cm-long S. areira branches from 10 plants, recording the presence and abundance of each species in relation to the molle phenological stages. Six hundred and seventy nine specimens were collected: Hemiptera (396), Lepidoptera (122), Thysanoptera (104), Hymenoptera (34), Diptera (13), Coleoptera (9) and Neuroptera (1). The most relevant species in terms of abundance of specimens, distribution and degree of damage caused to foliage of the plant were: Calophya schini (Hemiptera), a cecidogenous species found on leaves, and the defoliating species Tolype guentheri (Lepidoptera). Anthophilous species were represented by Thysanoptera, such as Thrips tabaci, Frankliniella australis, F. gemina, F. occidentalis and F. valdiviana. Fruits were attacked by Megastigmus sp. (Hymenoptera) and Lithraeus sp. (Coleoptera). Among beneficial species, the parasitoid Horismenus sp. (Hymenoptera) of T. guentheri was observed. Among predators of thrips, aphids and scale insects, specimens of Anthocoridae (Hemiptera), Hyperaspis sp. (Coleoptera: Coccinellidae) and Hemerobiidae (Neuroptera) were recorded.
A Class of Inexact Variable Metric Proximal Point Algorithms
A Class of Inexact Variable Metric Proximal Point Algorithms
Parente, Lisandro Armando; Lotito, Pablo Andres; Solodov, M. V.
For the problem of solving maximal monotone inclusions, we present a rather general class of algorithms, which contains hybrid inexact proximal point methods as a special case and allows for the use of a variable metric in subproblems. The global convergence and local linear rate of convergence are established under standard assumptions. We demonstrate the advantage of variable metric implementation in the case of solving systems of smooth monotone equations by the proximal Newton method.
Age-related lung cell response to urban Buenos Aires air particle soluble fraction
Age-related lung cell response to urban Buenos Aires air particle soluble fraction
Ostachuk, Agustin Ignacio; Evelson, Pablo Andrés; Martin, Susana; Dawidowski, Laura Elena; Yakisich, J. Sebastián; Tasat, Deborah Ruth
Exposure to particulate matter (PM) may alter lung homeostasis inducing changes in fluid balance and host defense. Bioavailability of soluble PM compounds like polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and transition metals has been shown to play a key role in lung injury. We have previously characterized the size, shape, and chemical components of urban air particles from Buenos Aires (UAP-BA) and their biological impact on lungs. Herein, we evaluate the possible toxic effect of UAP-BA-soluble fraction (UAP-BAsf) on pulmonary cells obtained from young (1-2 months old) and aged (9-12 months old) Wistar rats using phagocytosis, oxidant-antioxidant generation, and apoptosis as endpoints. UAP-BA were collected in downtown BA and residual oil fly ash (ROFA), employed as a positive control, was collected from Boston Edison Co., Mystic Power Plant, Mystic, CT, USA. Both particle-soluble fractions (sf) were employed at concentrations ranging from 0 to 100 microg/mL. UAP-BAsf and ROFAsf even at the lowest dose assayed (10 microg/mL) showed in both lung cell populations the ability to stimulate phagocytosis and increase superoxide anion (O(2)(-)) generation. Both types of air particles caused a marked intracellular oxidant stress in aged pulmonary cells that may contribute to subsequent cell activation and production of proinflammatory mediators, leading to cell dysfunction. These data suggest that the impact of UAP-BAsf on phagocytosis, oxidant radical generation, and apoptosis is clearly dependent on the maturational state of the animal and might have different mechanisms of action.
Sympatry inference and network analysis in biogeography
Sympatry inference and network analysis in biogeography
Dos Santos, Daniel Andrés; Fernandez, Hugo Rafael; Cuezzo, Maria Gabriela; Dominguez, Eduardo
A new approach for biogeography to find patterns of sympatry, based on network analysis, is proposed. Biogeographic analysis focuses basically on sympatry patterns of species. Sympatry is a network (= relational) datum, but it has never been analyzed before using relational tools such as Network Analysis. Our approach to biogeographic analysis consists of two parts: first the sympatry inference and second the network analysis method (NAM). The sympatry inference method was designed to propose sympatry hypothesis, constructing a basal sympatry network based on punctual data, independent of a priori distributional area determination. In this way, two or more species are considered sympatric when there is interpenetration and relative proximity among their records of occurrence. In nature, groups of species presenting within-group sympatry and between-group allopatry constitute natural units (units of co-occurrence). These allopatric units are usually connected by intermediary species. The network analysis method (NAM) that we propose here is based on the identification and removal of intermediary species to segregate units of co-occurrence, using the betweenness measure and the clustering coefficient. The species ranges of the units of co-occurrence obtained are transferred to a map, being considered as candidates to areas of endemism. The new approach was implemented on three different real complex data sets (one of them a classic example previously used in biogeography) resulting in (1) independence of predefined spatial units; (2) definition of co-occurrence patterns from the sympatry network structure, not from species range similarities; (3) higher stability in results despite scale changes; (4) identification of candidates to areas of endemism supported by strictly endemic species; (5) identification of intermediary species with particular biological attributes. Copyright © Society of Systematic Biologists.
The cactus-specialist bees of the genus brachyglossula Hedicke (Hymenoptera: Colletidae): Notes on host associations and description of a new species
The cactus-specialist bees of the genus brachyglossula Hedicke (Hymenoptera: Colletidae): Notes on host associations and description of a new species
Roig Alsina, Arturo Hernan; Schlumpberger, Boris O.
The pollen-collecting behavior of three species of the South American Andean bee genus Brachyglossula is reported. Species studied are B. martinezi Trucco Alemn, B. communis Trucco Alemn, and B. ancasti Roig Alsina and Schlumpberger, new species. The new species, which is comparatively described and illustrated, inhabits the isolated mountain range of Sierra de Ancasti, in the province of Catamarca, Argentina. Observation of the bees in the field, and pollen counts from scopal loads strongly support specialization of these bees on the Cactaceae. Members of both major cactus subfamilies, the Opuntioideae and the Cactoideae, are frequently visited and represented in the pollen loads.
QTL detection for milk production traits in goats using a longitudinal model
QTL detection for milk production traits in goats using a longitudinal model
Roldán, D.L.; Rabasa, Alicia Elvira; Saldaño, S.; Holgado, F.; Poli, M. A.; Cantet, Rodolfo Juan Carlos
Summary Eight paternal half-sib families were used to identify chromosomal regions associated with variation in the lactation curves of dairy goats. DNA samples from 162 animals were amplified by PCR for 37 microsatellite markers, from Capra hircus autosomes CHI3, CHI6, CHI14 and CHI20. Milk samples were collected during 6 years, and there were 897 records for milk yield (MY) and 814 for fat (FP) and protein percentage (PP). The analysis was conducted in two stages. First, a random regression model with several fixed effects was fitted to describe the lactation function, using a scale (α) plus four shape parameters: β and γ, both associated with a decrease in the slope of the curve, and δ and φ that are related to the increase in slope. Predictions of α, β, γ, δ and φ were regressed using an interval mapping model, and F-tests were used to test for quantitative trait loci (QTL) effects. Significant (p < 0.05) QTLs were found for: (i) MY: CHI6 at 70-80 cM for all parameters; CHI14 at 14 cM for δ and φ; (ii) FP: CHI14, at 63 cM was associated with β; CHI20, at 72 cM, showed association with α; (iii) PP: chromosomal regions associated with β were found at 59 cM in CHI3 and at 55 cM in CHI20 with α and γ. Analyses using more families and more animals will be useful to confirm or to reject these findings. © 2008 Blackwell Verlag, Berlin.
Effects of natural phenolic compounds from a desert dominant shrub Larrea divaricata Cav. on toxicity and survival in mice
Effects of natural phenolic compounds from a desert dominant shrub Larrea divaricata Cav. on toxicity and survival in mice; Efectos de los compuestos fenólicos naturales de un arbusto dominante del desierto, Larrea divaricata Cav. sobre la toxicidad y sobrevida en ratones
Ríos, Juan Manuel; Mangione, Antonio Marcelo; Gianello, Jose Carlos
Los herbívoros generalistas pueden evitar la intoxicación ingiriendo pequeñas cantidades de una mezcla de metabolitos secundarios de plantas. Sin embargo, un solo compuesto, uno altamente tóxico o el más abundante en la mezcla es el que podría causar la intoxicación. La sobrevida y la toxicidad en ratones Rockland machos fueron evaluadas para determinar si los efectos tóxicos de la resina fenólica de jarilla (Larrea divaricata Cav.) se debe a su compuesto mayoritario, el ácido nordihidroguaiarético (ANDG) o a la concentración total de compuestos fenólicos en esta resina. Este objetivo fue logrado mediante la exposición de ratones a la alimentación voluntaria de alimento para rata tratado con resina y mediante el gavage oral de ratones con las siguientes dosis y compuestos: Resina-100 mg (n = 7), ANDG-15 mg (n = 8), ANDG-100 mg (n = 10) y Control (n = 6). Nuestra hipótesis fue que los efectos tóxicos de Larrea divaricata son atribuibles al ANDG solamente. La ingesta voluntaria de resina por ratones tuvo un efecto tóxico pronunciado, evidenciado en una pérdida en masa corporal y una reducción significativa de la ingesta de alimento. Ratones expuestos a gavage con Resina-100 mg, ANDG-100 mg y ANDG-15 mg mostraron una reducción significativa de la sobrevida comparada con ratones bajo las condiciones Control. Animales expuestos a ANDG-15 mg tuvieron una mayor sobrevida comparado con animales expuestos a ANDG-100 mg y una sobrevida equivalente a los animales expuestos a Resina-100 mg (que contiene a su vez 15 mg de ANDG). No se detectaron diferencias significativas en la detoxificación medida como conjugados de ácido glucurónico en orina entre los tratamientos de gavage. Dado que 15 mg de ANDG fueron suficientes para producir el mismo efecto que la resina total, sugerimos que el ANDG es el constituyente principal de la resina de Larrea divaricata responsable del efecto tóxico de esta planta.; It is known that generalist herbivores may circumvent intoxication by ingesting small quantities from a mixture of plant secondary metabolites. However a single chemical, a highly toxic one or the most abundant in the mixture could cause toxicity. Survivorship and toxicity in Rockland male mice were measured to determine if the toxic effects of the phenolic resin of creosote bush (Larrea divaricata Cav.) is due to its major constituent, the nordihydroguaiaretic acid (NDGA) or to the total concentration of phenolic compounds in this resin. This objective was accomplished by exposing mice to voluntary feeding on resin-treated rat chow and by oral gavaging of mice with the following doses and compounds: Resin-100 mg (n = 7), NDGA-15 mg (n = 8), and NDGA-100 mg (n = 10) and Control (n = 6). Our hypothesis was that NDGA is responsible for the toxicity of Larrea divaricata's phenolic resin. Voluntary resin intake by mice had a pronounced toxic effect, producing body mass loss and significant reduction of food intake. Mice gavaged with Resin-100 mg, NDGA-100 mg, and NDGA-15 mg showed a significant reduction in survival probability compared to mice under Control conditions. Animáis exposed to NDGA-15 mg had a higher survivorship compared to the NDGA-100 mg animáis, and equivalent survivorship to the Resin-100 mg (containing 15 mg of NDGA) animáis. No significant differences in detoxification, measured as glucuronic acid conjugates in urine, were detected among gavage treatments. Therefore, given that just 15 mg of NDGA were enough to produce the same effect as the whole resin, we suggest that NDGA is the main constituent of Larrea divaricata's resin responsible for the toxic effect of the phenolic resin of this plant.
Prognostic value of Bcl-2 in breast cancer patients treated with neoadjuvant anthracycline based chemotherapy
Prognostic value of Bcl-2 in breast cancer patients treated with neoadjuvant anthracycline based chemotherapy
Vargas Roig, Laura Maria; Cuello Carrión, Fernando Darío; Fernández-Escobar, Nicolás; Daguerre, Pedro; Leuzzi, Marcela; Ibarra, Jorge; Gago, Francisco E.; Nadin, Silvina Beatriz; Ciocca, Daniel Ramon
We have analyzed the predictive/prognostic value of Bcl-2 protein in breast cancer patients treated with neoadjuvant chemotherapy. One hundred and ten patients were submitted to two different chemotherapeutic regimens: a) 5-fluorouracil, adriamycin or epirubicin, and cyclophosphamide (FAC/FEC) during 2-6 cycles before surgery and 3 or 4 additional cycles of FAC/FEC after surgery (n = 40) and b) doxorubicin (D) 75 mg/m2 or epirubicin (E) 120 mg/m2 during 4 cycles before surgery, and 6 cycles of cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) after surgery (n = 70). Bcl-2 expression, evaluated by immunohistochemistry, did not change significantly after chemotherapy and was not related to clinical/pathological response. In FAC/FEC group, Bcl-2 positive expression after chemotherapy correlated with better disease free survival (DFS) and overall survival (OS) (P = 0.008 and P = 0.001). In D/E group, Bcl-2 also correlated with better DFS and OS (P = 0.03 and P = 0.054) in the post-chemotherapy biopsies. An unusual nuclear localization of Bax was observed in some biopsies, but this localization did not correlate with the tumor response or outcome of the patients. We found that a high Bcl-2 expression had no predictive value but had prognostic value in breast cancer patients treated with neoadjuvant anthracycline based chemotherapy.
Ear tufts in Ferruginous Pygmy-Owl (Glaucidium brasilianum) as alarm response
Ear tufts in Ferruginous Pygmy-Owl (Glaucidium brasilianum) as alarm response
Santillan, Miguel Angel; Sarasola, José Hernán; Dolsan, Marcelo
Eficiencia relativa de distintas técnicas de captura de heterópteros terrestres en un pastizal de montaña
Eficiencia relativa de distintas técnicas de captura de heterópteros terrestres en un pastizal de montaña
Marrero, Hugo Javier; Zalba, Sergio Martín; Carpintero, Diego Leonardo
Los insectos habitan múltiples micro-ambientes y tienen nichos tróficos muy variados, razón por la cual existen diversas alternativas para su detección. En este trabajo se testeo el uso de distintas técnicas de captura de heterópteros terrestres sobre un pastizal de montaña, procurando la técnica o la combinación de técnicas que mejor representara la diversidad del grupo y que insumiera el menor esfuerzo, de manera de optimizar acciones de monitoreo. El trabajo se realizó durante las cuatro estaciones del año, sobre cuatro niveles altitudinales en la ladera del Cerro Curamalal (provincia de Buenos Aires) usando trampas de caída, red entomológica, trampa de luz y captura manual. La red entomológica resultó la técnica más eficiente, seguida por las trampas de caída, la captura manual y la trampa de luz. La combinación de captura manual y red entomológica rindieron los mejores resultados en términos de representación de la diversidad de heterópteros en el área de estudio. Se determinó además que la época de primavera-verano y los estratos intermedios de altura concentran la mayor diversidad específica del grupo.; Insects thrive in multiple micro-habitats and correspond to diverse trophic niches which is why there are multiple and diverse alternatives for their sampling. In this study we tested different techniques for capturing terrestrial heteropterans in a mountain grassland searching for the technique or combination of techniques that best represented this group´s biodiversity in the area. Sampling took place during all four seasons at four altitudinal levels on the Curamalal hill (Buenos Aires province) and we compared pit-fall traps, entomological net, light traps, and manual capture. When considering each technique separately, entomological nets rendered the best performance, followed by pit-fall traps, manual capture and light traps. The combination of entomological net and manual capture resulted in the best representation of heteropteran diversity in the study area. Spring and summer and intermediate heights on the hills concentrate the highest species diversity in this group of insects.
Deactivation studies of the SCR of NOx with hydrocarbons on Co-mordenite monolithic catalysts
Deactivation studies of the SCR of NOx with hydrocarbons on Co-mordenite monolithic catalysts
Boix, Alicia Viviana; Aspromonte, Soledad Guadalupe; Miro, Eduardo Ernesto
The catalytic reduction of NOx with hydrocarbons (butane or methane) on CoMOR washcoated monolithic catalysts was studied in the presence of steam and excess oxygen. The significant changes observed in the catalytic behavior of CoMOR powder and monoliths depended essentially on the hydrocarbon nature (carbon number) and the concentration of water in the feed. When the reducing agent was methane, a low concentration of water (2%) decreased the NO to N2 conversion. However, when butane was used instead of methane, the maximum NOx conversions increased from 50 to 58% and from 52 to 64% for the CoMOR powder and monolith, respectively. The presence of water inhibited the NO adsorption when the reducing agent was methane but when butane was used, water helped to remove the surface-carbon deposits as indicated by TPO and XPS results. This fact explains the increase observed in the NOx conversion. The characterization with TPR and UV-vis spectroscopy showed that the main Co species present in the selective catalysts were the Co(II) ions exchanged at different sites of the mordenite and highly dispersed CoxOy moieties. More rigorous reaction conditions, i.e. 10% of water, led to the irreversible deactivation with both reductants. The Co3O4 phase was detected in all the deactivated powder and monolithic catalysts. The Co3O4 spinel was formed from the cobalt ion migration, which was promoted in wet atmosphere. In addition, for monolithic catalysts washcoated with CoMOR, the silica binder inhibited the water deactivation effect probably due to the silica-cobalt interaction, as a CoxOySi silicate.
The ATLAS Experiment at the CERN Large Hadron Collider
The ATLAS Experiment at the CERN Large Hadron Collider
Piegaia, Ricardo Nestor; Aad, G.; Romeo, G.; Sanchis Lozano, M.A; Miyagawa, P.S.; Antonelli, S.; Bendel, M.; Breiler, B.; Castrovillari, F.; Civera, J.V.; Del Prete, T.; Duffin, S.; Fichet, S.; Gaumer, O.; Goodrick, M. J.; Goujdami, D.; Herten, G.; Jeremie, A; Kieft, G.; König, S.; Kirk, J.; Lapin, V.V.; LeGeyt, B.C.; Love, J.; Merola,L.; Raith, B.; Plamondon, M.; Saavedra, A.F.; Schott, M.; Soloviev, I.
The ATLAS detector as installed in its experimental cavern at point 1 at CERN is described in this paper. A brief overview of the expected performance of the detector when the Large Hadron Collider begins operation is also presented.
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