Difosfine bieteroariliche a chiralita' atropisomerica: applicazioni catalitiche e sviluppi

Dottorato di ricerca in chimica industriale. 12. ciclo. A.a. 1998-1999. Coordinatore Francesco Minisci. Relatore Edoardo CesarottiConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 , Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Caracterización de sondeos estivales del norte de Mendoza mediante el análisis de componentes principales y obtención de un índice de convección Characterization Of Summer Soundings From Northern Mendoza By Principal Components Analysis And The Obtaining Of A Convection Index

Se utilizó el análisis de componentes principales para caracterizar radiosondeos estivales del norte de Mendoza, evaluando su capacidad para identificar patrones asociados a la ocurrencia de convección y definiendo un índice de inestabilidad. Se tomaron 326 casos, construyendo una matriz de anomalías de temperatura (T) y temperatura de punto de rocío (Td) de los niveles estándar entre 850 y 300 hPa. El análisis arrojó 6 componentes significativas que explican más del 91% de varianza. Así se obtuvieron 12 patrones que representan condiciones atmosféricas diferenciadas. Las mayores correlaciones entre patrones y casos de convección (C) y no convección (NC), se obtuvieron para las componentes 6, 2, 4 y 3. La convección se favorecería en entornos relativamente húmedos con un marcado gradiente de T en niveles medios y altos, mientras se inhibiría con capas secas en niveles medios y altos, y débiles gradientes de T en capas bajas. El indicador de C/NC puede estimarse por regresión múltiple logística dependiente de las componentes de carga, con una correlación conjunta de 0,5, determinando un índice de estabilidad/inestabilidad calculable a partir de los perfiles de T y Td y dependiente de las características climatológicas de la región. El índice mostró una efectividad del 72%.<br>The Principal Components Analysis was used to characterize the summery North Mendoza rawinsondes, evaluating their capacity to identify patterns associated to the convection occurrence and defining an instability index. It was selected 326 cases, building an entry matrix with the temperature and dew point temperature anomalies for the standard levels between 850 and 300 hPa. The analysis showed 6 significant components that explain more than 91% of variance. Therefore, 12 patterns were obtained, which represent different atmospheric conditions. The main correlations between the patterns and convection (C) and non convection (NC) cases were obtained for the components 6, 2, 4 and 3. The relatively wet environments with a strong gradient of T at mean and high levels would favour the convection, while it is inhibited with dry layers in mean and high levels, and weak gradients of T in low layers. The C/NC index can be estimated by a logistic multiple regression dependent to the component loadings, with a correlation of 0,5, determining a stability/instability index calculable from the T and Td profiles and it depends on the climatological features of the region. The index showed an efficiency of 72%

Precipitation events prediction that causes debris flow and landslides over mountainous area on norwest region of Mendoza province, Argentina

La predicción de precipitación en terrenos de orografía compleja especialmente donde las características del suelo presentan una tendencia a producir aludes, es de vital importancia desde el punto de vista estratégico a finde evitar posibles accidentes.Como consecuencia de episodios de tormentas intensas en el entorno de la Ruta Internacional Nº 7, que conecta la Argentina con el Océano Pacifico (Chile), suelen generarse grandes flujos de detritos o caídas de rocas queocasionan la interrupción del tránsito internacional. Dependiendo de la magnitud de estos aludes, los cortes de esta ruta suelen ocurrir a veces por períodos prolongados, poniendo en peligro la seguridad de las personas que la transitan y generando trastornos de índole comercial.El objetivo principal de este trabajo es analizar cuáles son los forzantes sinópticos más relevantes que ocasionan este tipo de eventos tratando, como objetivo secundario, de evaluar la mayor o menor habilidad de los modelosregionales (WRF y Eta/ PRM) para predecir eventos de precipitación en una zona topográficamente compleja ycarente de mediciones sistemáticas. Se analizaron cuatro episodios: 27 de marzo de 2007, 13 de enero de 2013, 7y 8 de febrero de 2013 y 25 de febrero de 2014.Las situaciones sinópticas que contribuyen a la ocurrencia de estos aludes tienen el común denominador depresentar características bien definidas como la anomalía negativa de la componente zonal del viento entre losniveles de 850 y 400 hPa.La validación de los pronósticos se llevó a cabo mediante el uso de estaciones meteorológicas del Servicio Meteorológico Nacional, de la Superintendencia de Irrigación de la provincia de Mendoza y con estimaciones deprecipitación global a partir de datos infrarrojos y de microondas pasivas en alta resolución espacial (8 km) y temporal (30 minutos) método conocido como CMORPH (Joyce et al., 2004).Los modelos numéricos de la atmósfera tales como WRF y Eta-PRM predicen, aunque sobreestimando, la precipitación en la zona de topografía compleja analizada y que el método CMORPH es un potencial elemento de validación en zonas con dichas características.Precipitation prediction on complex terrain, especially where the soil is vulnerable for landslides occurrence, is an important tool to prevent accidents. Severe storms along the 7 International Route that connects Argentina with Pacific Ocean (Chile) causes debris flow and landslides interrupting the international traffic. Sometimes, if the episode is severe, the blocking is large generating commercial problems and danger for the people. The principal aim of this paper is to analyze the relevant synoptic conditions that favour the occurrence of landslides and a secondary objective is to evaluate the ability of regional models such as the Weather Research and Forecasting (WRF) and Eta/MRP (Meteorological Regional Program) to predict precipitation events in a complex terrain area with a meteorological network of low density. Four events that ocasioned landslides were analyzed, namely March 27th 2007, January 13th 2013, February 7th and 8th 2013 and February 25th 2014. Negative anomaly of zonal wind between 850 hPa and 400 hPa level is one of the common synoptic characteristics for these episodes analyzed. Forecast validation was carried out by using surface data from a meteorological network of National Weather Service of Argentina, Irrigation Bureau of Mendoza province and the precipitation estimation by the CMORPH method (Joyce et al., 2004). It was observed that numerical models can predict these heavy precipitating events however with an overestimation. It worth noting that CMORPH is a good tool to estimate precipitation in mountainous terrain.Fil: Santos, Jorge Ruben. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Norte, Federico Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Moreiras, Stella Maris. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Araneo, Diego Christian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Simonelli, Silvia Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Humulus lupulus L. cv. Cascade grown in Northern Italy: morphological and phytochemical characterization

Several aroma hops (Humulus lupulus L.) were recently introduced in Northern Italy as a small-scale production of excellence. In this preliminary study, the American cultivar Cascade was investigated in a combined morphological and phytochemical survey. Morphological investigation on trichome structure, density and distribution was performed by scanning electron microscopy and light microscopy. Essential oil composition, α/β-acid and polyphenol profiles over 3 years were determined by GC-MS and HPLC analyses. Two types of non-glandular (simple and cystolithic) and glandular (peltate and bulbous) trichomes were observed on leaves and female inflorescences. The peltate trichomes resulted as the main sites of terpene production and accumulation. The essential oil profiles showed myrcene, β-caryophyllene, (E)-β-farnesene and humulene epoxide II as the dominant compounds over the three collection times, although with different relative abundances. The presence of two exclusive compounds, γ-muurolene and trans-γ-cadinene, characterized the investigated cv. Cascade, potentially enhancing herbal, woody and spicy aroma traits of this cultivation in Northern Italy. The bitter acid composition showed quantitative values consistent with literature data only for the second and third monitoring year. Qualitative differences in polyphenol content were also recorded, for the presence of quercetin-3-O-malonylglucoside and kaempferol-3-O-rutinoside, which may characterize this peculiar Italian cultivation

Electroactive bio-based chiral tweezers: Attractive selectors for enantioselective voltammetry

Ionic liquids (ILs), either chiral in themselves (CILs) or modified with small quantities of CILs or related chiral molecular salts as chiral additives, have been proposed as an effective tool to achieve enantiodiscrimination in terms of potential differences in voltammetric electroanalysis, on account of their high local order at the electrode | solution interphase. Successful cases already explored range from biobased CILs (or related chiral additives) including terpenol or bile acid building blocks, having stereocentres as stereogenic elements, to CILs (or related chiral additives) with “inherently chiral” scaffolds based on biheteroaromatic atropisomeric cores. A further attractive family of CILs and related compounds worthy to be explored is based on chiral “tweezer” dications consisting of a biobased isomannide or isosorbide chiral core with two cation arms which include heteroatoms and aromatic systems, thus providing many coordination elements for selector/probe interactions. A wide, systematic series of such chiral tweezers is presented, characterized in terms of thermal features (by thermal gravimetric analysis and differential scanning calorimetry) and stereochemical properties (by electronic circular dichroism spectroscopy), and submitted to an exhaustive electrochemical study to highlight and rationalize their redox properties. Successful preliminary chiral voltammetry tests, performed employing rac-N-3,5-dinitrobenzoyl phenylglycine methyl ester (DNB-PhGly) as well as 2,2,2-trifluoro-1-(9-anthryl)ethanol (TFAE) as chiral electroactive probes in combination with selected tweezers, confirm the attractiveness of the biobased tweezer family as chiral selectors for enantioselective electroanalysis

Widening the Scope of \u201cInherently Chiral\u201d Electrodes: Enantiodiscrimination of Chiral Electroactive Probes with Planar Stereogenicity

A series of planar-stereogenicity ferrocenes, important as chiral promoters in enantioselective catalysis, is characterized in terms of relationships between structure and electronic properties. The enantiomers of six selected model cases are then successfully discriminated in voltammetry experiments on electrodes modified with electrodeposited inherently chiral oligomer films, in terms of significant potential differences, specular inverting probe or selector configuration. Small substituent changes do not alter the enantiomer peak sequence, but result in significant modulation of peak potential differences, which appear consistent with the availability of chiral/selector matching elements. The present stereogenic plane case, combined with former ones involving stereogenic centers, axes, and/or helices, shows that the inherent chirality strategy in electroanalysis can be effective with all four rigid stereogenic elements