The University of Belgrano is a private university established in 1964 and located in the Belgrano district of the city of Buenos Aires, Argentina.It has 9 Departments:Architecture and Urban PlanningLaw and Political ScienceEconomicsHumanitiesEngineering and Computer TechnologyAgricultural scienceLanguage and Foreign StudiesHealth scienceApplied scienceThe school operates 90.9 FM, a station featuring eclectic programming and daily BBC News broadcasts. Wikipedia.
Barata-Vallejo S.,University of Buenos Aires |
Postigo A.,University of Belgrano
Journal of Organic Chemistry | Year: 2010
Figure presented. Perfluoroalkyl-substituted compounds are regarded as important components of fluorophors and for the introduction of fluorous tags into organic substrates. Their syntheses in organic solvents are achieved through different methods, among which, the addition of perfluoroalkyl radicals to unsaturated bonds represents a convenient choice. On the other hand, intermolecular radical reactions in water have attracted the attention of synthetic chemists as a strategic route to carbon-carbon bond formation reactions. In this paper we undertook the intermolecular addition of perfluoroalkyl radicals on electron rich alkenes and alkenes with electron withdrawing groups in water, mediated by silyl radicals, and obtained perfluoroalkyl-substituted compounds in fairly good yields. The radical triggering events employed consist of the thermal decomposition of an azo compound and the dioxygen initiation. Our results indicate that for intermolecular carbon-carbon bond formation reactions mediated by (Me 3Si)3SiH, the decomposition of the azo compound 1,1′-azobis(cyclohexanecarbonitrile) (ACCN) is the best radical initiator. We also found that water exerts a relevant solvent effect on the rates of perfluoroalkyl radical additions onto double bonds and the H atom abstraction from the silane. Our account provides a versatile and convenient method to achieve perfluoroalkylation reactions of alkenes in water to render perfluoroalkylated alkanes as key intermediates in the synthesis of fluorophors and other fluorinated materials. This is the first report where perfluoroalkyl-substituted alkanes are synthesized through intermolecular radical carbon-carbon bond formation reactions in water, mediated by silyl radicals. © 2010 American Chemical Society.
Fernandez D.C.,University of Buenos Aires |
Fernandez D.C.,University of Moron |
Pasquini L.A.,University of Buenos Aires |
Dorfman D.,University of Buenos Aires |
And 3 more authors.
American Journal of Pathology | Year: 2012
Diabetic retinopathy is a leading cause of acquired blindness. Visual function disorders have been observed in diabetic patients with very early retinopathy or even before the onset of retinopathy. The aim of the present work was to analyze the visual pathway in an early stage of experimental diabetes. Diabetes was induced in Wistar rats by an i.p. injection of streptozotocin. A deficit in anterograde transport from the retina to the superior colliculus was observed 6 weeks after streptozotocin injection. At this time point, morphologic studies did not reveal retinal ganglion cell loss or substantial alterations in the superior colliculus. The optic nerve was morphometrically evaluated at intraorbital (unmyelinated and myelinated) and intracranial sections. In animals that had been diabetic for 6 weeks, a large increase in astrocyte reactivity occurred in the distal (but not the intraorbital) portion, which coincided with significant axon loss. Moreover, profound myelin alterations and altered morphologic features of oligodendrocyte lineage were observed at the distal (but not the proximal) optic nerve portion. The present results suggest that axoglial alterations at the distal portion of the optic nerve could be the first structural change in the diabetic visual pathway. © 2012 American Society for Investigative Pathology.
Postigo A.,University of Belgrano |
Nudelman N.S.,University of Buenos Aires
Journal of Physical Organic Chemistry | Year: 2010
The relevance of radical initiation methodologies for the classical hydrosilylation reactions of organic compounds bearing C-C multiple bonds is due to the need to come up with newer and more efficient methods to effect this reaction, on account of its applications on surface chemistry. In the past, when organic solventswere employed, thermal and photochemical methods for the chain initiation reaction have been documented (thermal and photochemical decompositions of azo compounds). We herein present the dioxygen-initiation technique of the classical radical hydrosilylation reaction of C-C triple bonds with tris(trimethylsilyl)silane ((Me3Si)3SiH) in water. This initiation technique is confronted with the photochemical radical initiation in the absence of a chemical radical precursor other than the silane and also confronted with the classical thermal initiation triggered by the decomposition of an azo compound, both performed in water. The radical-based dioxygen initiation methodology studied in water is shown to afford the highest Z:E stereoselective ratios of hydrosilylated alkenes. Copyright © 2010 John Wiley and Sons, Ltd.
Muller F.,University of Belgrano |
Palavezzatti M.C.,Maria Carolina Palavezzatti
Revista Argentina de Clinica Psicologica | Year: 2015
The aim of this article is to provide information about the relationship between theoretical orientation and clinical practice in Buenos Aires. Data was gathered from a sample of 314 psychotherapists in hospitals of the City of Buenos Aires and Gran Buenos Aires. The psychoanalytic model emerged as the predominant model, representing 52.9% of the sample. Integrative models, with 41.7% of the sample, were the second largest group. Within the group of integrationists, 61% of psychotherapists reported using psychoanalytic theory as the main theory, followed by a cognitive theory, reported by 19.1%. These results reveal both the importance of psychoanalysis in Buenos Aires, and the trend towards integrationism. © 2015 Fundación AIGLÉ.
Francescato L.N.,Federal University of Rio Grande do Sul |
Debenedetti S.L.,University of Belgrano |
Schwanz T.G.,Federal University of Santa Maria |
Bassani V.L.,Federal University of Rio Grande do Sul |
Henriques A.T.,Federal University of Rio Grande do Sul
Talanta | Year: 2013
Equisetum giganteum L., commonly called giant horsetail, is an endemic species of Latin America. Its aerial parts have been widely used in ethnomedicine as a diuretic and in herbal medicine and food supplements as a raw material. The phenolic composition of E. giganteum stems was studied by liquid chromatography coupled to diode array detection (LC-DAD) and liquid chromatography coupled to electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS), which identified caffeic acid derivatives, flavonoids and styrylpyrones. The most abundant glycosilated flavonoids in this sample were kaempferol derivatives. Other rare phenolic components, namely, quercetin-3-O-(caffeoyl)-glucoside and 3-hydroxyhispidin-3,4′-di-O- glucoside, were reported for first time in the Equisetum genus. An LC-UV method for the simultaneous quantification of flavonoid aglycones in E. giganteum obtained after hydrolysis was developed and validated. The method exhibited excellent linearity for all analytes, with regression coefficients above 0.998, LOD≥0.043 μg mL-1, LOQ≥0.158 μg mL-1 and recovery rates of 96.89-103.33% and 98.22-102.49% for quercetin and kaempferol, respectively. The relative standard deviation for the intra- and inter-day precision was≤3.75%. The hydrolysis process was optimized by central composite rotational design and response surface analysis. The second-order response models for the aglycones contents were as follows: quercetin (μg g-1)=24.8102+55.2823×HCl+0.776997×Time-7. 23852×HCl2-7.46528E-04×Time2- 0.229167×HCl×Time; kaempferol (μg g-1)=-9.66755+974. 822×HCl+11.8059×Time-130.612×HCl2-0. 0125694×Time2 -3.22917×HCl×Time, with estimated optimal conditions of 1.18 M HCl and 205 min of hydrolysis. The results obtained with these new methods were compared to those from a spectrophotometric assay used to determine the total flavonoids in the Equisetum arvense monograph (Horsetail, British Pharmacopoeia 2011). For all four species analyzed (E. giganteum, E. arvense, E. hyemale and E. bogotense), the calculated aglycone content was higher using the optimized hydrolysis conditions. Additionally, the LC method was more appropriate and specific for quantitative analysis. © 2012 Elsevier B.V.