Agrupaciones estelares y la estructura del segundo cuadrante galáctico

Los cúmulos estelares y las regiones de formación estelar son considerados importantes objetos para la investigación astrofísica (p.e. Portegies Zwart et al. 2010). Sus características particulares los hacen muy útiles en diversos aspectos. Aproximadamente el 80 % de las estrellas de las regiones de formación estelar se encuentran en cúmulos por lo tanto son ideales para estudiar las primeras etapas de formación y evolución estelar (Lada & Lada 2003; Porras et al. 2003). Están formados por estrellas de aproximadamente la misma edad con un rango de masas estelares amplio lo cual permite derivar sus parámetros fundamentales: tamaños, excesos de color, distancias y edades. Debido a que los cúmulos jóvenes son importantes trazadores de los brazos espirales (Baume et al. 2006; Sung et al. 2013) desempeñan un papel fundamental en la comprensión de la estructura Galáctica. En este trabajo de tesis estudiamos un conjunto de 19 agrupaciones estelares jóvenes ubicadas en el segundo cuadrante Galáctico. Para ello, utilizamos fotometría en el óptico e infrarrojo: SDSS (Ahn et al. 2012) y APASS (Henden et al. 2016), 2MASS (Cutri et al. 2003) y WISE (Cutri & et al. 2013), respectivamente. Teniendo en cuenta que para las regiones de los cúmulos la fotometría en el relevamiento SDSS se encuentra incompleta, hicimos uso de las imágenes FITS y realizamos fotometría de apertura. A su vez, empleamos datos espectroscópicos e información astrom´etrica del satélite Gaia (Lindegren et al. 2018). Las agrupaciones estelares fueron abordadas de manera sistemática, uniforme y homogénea, y seleccionadas a partir de un análisis preliminar realizado sobre 250 cúmulos listados en los catálogos “Milky Way global Survey of Star Clusters” (Kharchenko et al. 2013) y “New infrared star clusters in the Northern and Equatorial Milky Way with 2MASS” Bica et al. (2003b) . El estudio fotométrico, espectro–fotométrico y astrometría detallado nos permitió estimar y calcular sus parámetros fundamentales haciendo uso de tres técnicas de análisis distintas. De la construcción de los diagramas fotométricos multi–banda estimamos los parámetros fundamentales de las 19 agrupaciones estelares. Para 11 de ellas obtuvimos datos espectroscópicos propios del observatorio Gemini, y en conjunto con la espectroscopia recopilada de la bibliografía, realizamos un análisis espectro–fotométrico estableciendo excesos de color y distancias para 17 de los 19 cúmulos estelares. Adicionalmente, para 14 de las agrupaciones estelares derivamos resultados en distancia mediante datos Gaia Data Release 2. A partir de estos resultados investigamos la vinculación de las agrupaciones a la estructura y subestructura de la Vía Láctea redefiniendo su pertenencia a los diferentes brazos espirales, en particular, al denominado Nuevo Brazo más allá del Brazo Exterior introduciendo, a su vez, la presencia de una ramificación entre dos de los brazos principales.Facultad de Ciencias Astronómicas y Geofísica

Synthesis and Characterization of TiO2 Modified with olystyrene and Poly(3-chloro-2-hydroxypropyl Methacrylate) as Adsorbents for the Solid Phase Extraction of Organophosphorus Pesticides

ARTICULO DE INVESTIGACION EN REVISTA INDEXADANovel hy br i d Ti O2 particles were developed and assessed as an adsorbent for solid phase extraction (SPE) of organophosphorus pesticides (fensulfothion, parathion methyl, coumaphos, and diazinon) from spiked water. Th sol-gel method was used to synthesize TiO2 particles, which were coated with free-radical polystyrene (PS) and poly(3-chloro-2-hydroxypropyl methacrylate) (PClHPMA) polymers. Particle structures were determined via Fourier transform infrared spectroscopy to confim that the polymers were successfully anchored to the TiO2 particles. Thrmogravimetric analysis was conducted to determine organic and inorganic matter in TiO2-PS and TiO2-PClHPMA particles showing results of 20 : 80 wt/wt% and 23 : 77 wt/wt%, respectively. SEMEDS and X-ray diffaction test were conducted to determine the morphology and semielemental composition of the particles showing amorphous characteristics. By observing the contact angle, particles coated with PClHPMA were determined to be more hydrophilic than TiO2-PS particles. Th pore size distributions obtained from the N2 adsorption-desorption isotherms were 0.150 and 0.168 cm3g−1. Th specifi surface area (BET) was 239.9 m2g−1 for TiO2-PS and 225.7 m2g−1 for TiO2-PClHPMA. Th synthesized particles showed relatively high yields of adsorption in SPE. Th pesticide recoveries obtained by high performance liquid chromatography ranged from 6 to 26% for TiO2-PClHPMA and 44 to 92% for TiO2-PS.Consejo Nacional de Ciencia y Tecnología, CONACyT (83390

Synthesis and Characterization of TiO 2

Novel hybrid TiO2 particles were developed and assessed as an adsorbent for solid phase extraction (SPE) of organophosphorus pesticides (fensulfothion, parathion methyl, coumaphos, and diazinon) from spiked water. The sol-gel method was used to synthesize TiO2 particles, which were coated with free-radical polystyrene (PS) and poly(3-chloro-2-hydroxypropyl methacrylate) (PClHPMA) polymers. Particle structures were determined via Fourier transform infrared spectroscopy to confirm that the polymers were successfully anchored to the TiO2 particles. Thermogravimetric analysis was conducted to determine organic and inorganic matter in TiO2-PS and TiO2-PClHPMA particles showing results of 20 : 80 wt/wt% and 23 : 77 wt/wt%, respectively. SEM-EDS and X-ray diffraction test were conducted to determine the morphology and semielemental composition of the particles showing amorphous characteristics. By observing the contact angle, particles coated with PClHPMA were determined to be more hydrophilic than TiO2-PS particles. The pore size distributions obtained from the N2 adsorption-desorption isotherms were 0.150 and 0.168 cm3g−1. The specific surface area (BET) was 239.9 m2g−1 for TiO2-PS and 225.7 m2g−1 for TiO2-PClHPMA. The synthesized particles showed relatively high yields of adsorption in SPE. The pesticide recoveries obtained by high performance liquid chromatography ranged from 6 to 26% for TiO2-PClHPMA and 44 to 92% for TiO2-PS

Stellar populations in the Carina region : The Galactic plane at l = 291°

Context. Previous studies of the Carina region have revealed its complexity and richness as well as a significant number of early-type stars. However, in many cases, these studies only concentrated on the central region (Trumpler 14/16) or were not homogeneous. This latter aspect, in particular, is crucial because very di erent ages and distances for key clusters have been claimed in recent years. Aims. The aim of this work is to study in detail an area of the Galactic plane in Carina, eastward η Carina.We analyze the properties of di erent stellar populations and focus on a sample of open clusters and their population of young stellar objects and highly reddened early stars. We also studied the stellar mass distribution in these clusters and the possible scenario of their formation. Finally, we outline the Galactic spiral structure in this direction. Methods. We obtained deep and homogeneous photometric data (UBVIKC) for six young open clusters: NGC 3752, Trumpler 18, NGC 3590, Hogg 10, 11, and 12, located in Carina at l ~ 291°, and their adjacent stellar fields, which we complemented with spectroscopic observations of a few selected targets. We also culled additional information from the literature, which includes stellar spectral classifications and near-infrared photometry from 2MASS.We finally developed a numerical code that allowed us to perform a homogeneous and systematic analysis of the data. Our results provide more reliable estimates of distances, color excesses, masses, and ages of the stellar populations in this direction. Results. We estimate the basic parameters of the studied clusters and find that they identify two overdensities of young stellar populations located at about 1.8 kpc and 2.8 kpc, with EB-V ~ 0.1-0.6. We find evidence of pre-main-sequence populations inside them, with an apparent coeval stellar formation in the most conspicuous clusters. We also discuss apparent age and distance gradients in the direction NW-SE. We study the mass distributions of the covered clusters and several others in the region (which we took form the literature). They consistently show a canonical IMF slope (the Salpeter one). We discover and characterise an abnormally reddened massive stellar population, scattered between 6.6 and 11 kpc. Spectroscopic observations of ten stars of this latter population show that all selected targets were massive OB stars. Their location is consistent with the position of the Carina-Sagittarius spiral arm.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica

Unveiling the nature of clusters in the Cygnus region, I: the embedded cluster DB2001-22

The Cygnus region harbours a vast diversity of rich stellar complexes. Hence, it is ideal for studying recently formed stellar clusters, and investigate how the feedback effect and radiation emitted by its massive stars modifies the interstellar medium giving place to induced star forming processes. This is the case of the small and poorly studied cluster DB2001-22. We focus our attention at analysing the cluster and its encompassing region, to distinguish different stellar populations and study their relationship with the surrounding environment. We gleaned literature and data bases for optical and IR photometry, astrometry provided by Gaia eDR3 and spectroscopy, and obtained new infrared Gemini spectra of three young stellar objects candidates (cYSOs). Furthermore, we detected two new massive stars: O7 V and B3 V, in the LAMOST data base, pointing out that DB2001-22 belongs to a much larger complex that involves an entire bubble structure and houses a richer massive population at a distance of 3.0 kpc. In this sense, DB2001-22 and the H ii region G82.6+0.4 are clearly related. Some observed gas and dust structures seem to have been sculpted by these massive stars. Infrared emission is compatible with a hot ionized gas mixed with warm dust surrounded by a structured photo-dissociation region (PDR) scenario. We found nine Class I and 56 Class II cYSOs, whose distribution along the PDR and the tips of pillar structures suggests that their formation may have been induced by the action of the earliest stars in the cluster on to their environment.Fil: Molina Lera, José Alejo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Gamen, Roberto Claudio. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Cichowolski, Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Baume, Gustavo Luis. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Cárdenas, Silvina Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Universidad Nacional de La Plata; Argentin

Natural Beverages and Sensory Quality Based on Phenolic Contents

Currently, consumers are demanding natural products, with low sugar content and high nutritional and sensory qualities. Natural beverages have taken an important place due to their mineral, vitamin, and antioxidant contents. Phenolic compounds have great relevance for food industries for their functional properties acting as good antioxidant molecules as well as aging retarders and preventing degenerative diseases. In this connection, design of functional beverages rich in phenolic compounds has been related to the acceptability, quality, and safety for consumers; however, sensory properties regarding influence of these compounds are still poorly investigated. Recent works have been conducted in order to highlight the impact of phenolics on sensory properties of natural beverages. This chapter discusses the relationship between sensory quality and the phenolic compounds in natural beverages. The antioxidant properties, methods, and statistical analysis for sensory evaluation are also reviewed

Estudio multifrecuencia en la zona de RCW 116B

A partir de la combinación de datos de diferentes relevamientos en el óptico (VPHAS+), infrarrojo (2MASS, VVV), y radio (SGPS), se realizó un estudio de la región HII RCW 116B y su entorno. Estos datos fueron complementados con información obtenida de la bibliografía de algunos objetos particulares de la zona. Se llevó a cabo un análisis de las poblaciones estelares y de las estructuras del medio interestelar en esta región evaluando la vinculación entre las diferentes componentes. Se obtuvieron valores preliminares de sus principales características (densidad estelar, distancia, enrojecimiento y tamaño) y se identificaron algunos candidatos a YSOs.A study of the HII region of RCW 116B and its surroundings was performed using a combination of data from different surveys in the optical (VPHAS+), infrared (2MASS, VVV), and radio (SGPS). For some particular objects, these data were complemented with information gathered from the literature. It was carried out an analysis of the stellar populations and structures of the interstellar medium in this region assessing the possible relation between different components. We obtained preliminary values of the main features (stellar density, distance, reddening and size) and we identified some YSO candidates.Trabajo publicado en Actas de las Terceras Jornadas de Astrofísica Estelar. La Plata, Asociación Argentina de Astronomía, 2018.Facultad de Ciencias Astronómicas y Geofísica