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Science and Technology |
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Rodríguez, Yelitza |
Rodríguez, Yelitza; Bravo, Arnaldo*, Departamento de Ciencias y Tecnología - UIA-Recinto de Arecibo
Determinacion de sustancias en mezclas por espectroscopia infrarroja. Uso de CAChe en la identificación de algunos modos mormales de vibración
Aplicaciones cuantitativas de la espectroscopia infrarroja son poco frecuentes ya que es preferentemente usada para el análisis cualitativo (identificación) de sustancias. Este trabajo está dirigido fundamentalmente a la determinación cuantitativa y simultánea de la presencia de dos estructuras orgánicas sólidas mezcladas en una muestra: el ácido benzoico y el para-aminobenzoico. El procedimiento se enfoca primeramente en el registro del espectro de cada sustancia en estado puro (o mezclado en un solvente inerte) y posteriormente en la selección adecuada de una banda única y representativa de cada sustancia a partir de ese espectro. Se aplicó el Método de Línea Base para considerar la asimetría característica de cada banda o señal escogida y la determinación cuantitativa es obtenida calculando la absorbancia (A) por una relación logarítmica de los porcentajes de transmitancia relativos. Variaciones sistemáticas en la proporción de los componentes en diferentes mezclas permiten construir una curva de calibración, validada por su aplicación a muestras desconocidas que contienen ambas sustancias. Esta metodología puede proyectarse a la cuantificación directa de sustancias en mezcla como por ejemplo los productos resultantes de una síntesis que no tenga rendimiento óptimo. Se utiliza paralelamente un programa computacional (CAChe) para identificar algunos modos de vibración que permitan estimar aquellas bandas más susceptibles de ser seleccionadas para el análisis cuantitativo. Se aplicaron diversos métodos disponibles siendo Mopac PM5 el más representativo del registro experimental. Este último aspecto se desarrolló gracias a los fondos aportados por el proyecto MSEIP en Química: ”Integration of Chemistry and Biology Through Molecular Modeling”.
González Santiago, Miguel, Universidad Interamericana, Recinto de Arecibo, Dept. de Ciencias y Tecnología.
Estudio Molecular y Cálculo de Propiedades Termodinámicas de Ácido Hipofluoroso
El estudio teórico de moléculas poliatómicas es un campo de actualidad, gracias a los avances de la mecánica cuántica y las capacidades de las computadoras personales. Es de interés, el estudio molecular y el cálculo de propiedades termodinámicas de un ácido oxidante por su capacidad desinfectante en un ambiente real. Este trabajo presenta algunos resultados de simulación computacional, a través de distintos métodos semi-empíricos y Ab initio , de la estructura, propiedades moleculares y propiedades termodinámicas de HOF.
Además, se desarrolla un análisis del enlace H-O a través del cálculo de su curva de energía potencial. Simulaciones de este tipo de curvas se pueden obtener a partir del programa computacional de Gaussian 98 utilizando diversos métodos y cuyos resultados permiten encontrar mediante un ajuste de mínimos cuadrados una serie de parámetros, tales como la energía de disociación de enlace, constantes de fuerza y longitud de enlace en el equilibrio.
La investigación presentada en este trabajo se desarrolló gracias a los fondos aportados por el proyecto MSEIP en Química, “Integration of Chemistry and Biology through Molecular Modeling ” y el apoyo de la Universidad Interamericana de Puerto Rico.
Córdova, Daianyk*UPR-Mayagüez;
Design Guidelines to Address Urban Renewal in Río Piedras
As times change, cities around the world evolve and modernize. Priorities change and new urbanism techniques and concepts emerge. In the year 2003, San Juan will inaugurate Phase I of the Tren Urbano Project. This new transit system runs through a 17.2 km route which will connect 16 stations strategically located in commercial and residential areas with the highest population density, in hopes to reduce traffic congestion.
This research aims at developing design guidelines regarding sustainable development and key engineering elements for the Rio Piedras station. This poster presents the first stage of the research, which consisted on formulating a series of checklists as a basis for the Urban Analysis for the development of Design Guidelines. Their purpose is to increase the Tren Urbano ridership by helping to create a pedestrian friendly environment. A study area was established, here in as the Rio Piedras’ Station Zone of Influence. This area consists of 6 main sectors namely Government Owned Sectors, Santa Rita, Centro Urbano, University of Puerto Rico, Villa Universitaria and Comunidad Venezuela. Their landuse and boundaries were established and an extensive literature review was conducted to identify main problems in these areas. Next, the principal urban characteristics of the wealthiest and most livable cities in the world were identified. Then, in order to know about the future plans proposed for Rio Piedras by the Planning Board, an interview to the Coordinator of Planning Programs at this government agency was arranged. Information on landuse and zoning was gathered through construction managers and urban planners. After collecting all the information, possible solutions were recommended in order to contribute to make Rio Piedras a more livable community and emphasize the immediate importance of sustainable transportation and sustainable development to the future of Rio Piedras and the growing region.
Candelario, Dayamiris*UMET, Departamento de Ciencias y Tecnología; Aust, Mike, Department of Forestry, Virginia Polytechnic Institute and State University
Ameliorative Effect of Riparian Vegetation on Stream Indices
Riparian forests interact with the hydrology, soils, and vegetation to protect and improve water quality, provide habitat for organisms, support aquatic systems and provide societal benefits. Environmental benefits associated with riparian forests have generated interest in their study, management, conservation, and restoration. This research compared the ameliorative properties of three types of riparian. This involved periodic sampling of three indicators of stream health: temperature, dissolved oxygen and benthic organisms at Stroubles Creek, a first order perennial stream below the Duck Pond, a polluted water body belonging to Virginia Polytechnic Institute and State University, Blacksburg, Virginia. During summer, 2002, samples were collected on ten different days. Samples were collected from five replicates of the three treatments and from pools and riffles within each treatment. Analyses revealed that vegetation type was not as important to the recovery of the stream water quality indices as was the distance from the pond. As distance increased, the water was reoxygenated by riffles, the shading riparian vegetation slowly cooled the water, and benthic organism population indicated improved water quality.
Sánchez, Yaysa*UMET, Dept. Ciencias y Tecnologías; Higgins, Wayne National Oceanic and Atmospheric Administration
Interanual Variations in the Tropical Cyclone Activity in the Eastern Caribbean Region
A classification of El Niño / La Niña is used to determine relationships between Eastern Caribbean tropical cyclone activity and ENSO phase (El Niño Southern Oscillation). A 51-year (August-October 1950-2000) hurricane track data set is used to identify individual storms. A synoptic climatology of major tropical cyclones in the Eastern Caribbean is developed. These studies provide a foundation for in depth study of key meteorological characteristics and standard scenarios that accompany these tropical cyclones. Composites of the surface weather and tropospheric circulation patterns that accompany these storms are used to relate local weather conditions to the large-scale atmospheric circulation. In studying the relationship to ENSO, a total of 73 tropical cyclones were considered. During moderate/strong EL Niño events only 3 tropical cyclones were observed whereas during moderate/strong La Niña events 12 tropical cyclones were observed. Given that there were almost an equal number of moderate and strong El Niño and La Niña events (6 and 7 respectively) during August-October 1950-2000 (ASO), this indicates a statistically significant increase in the frequency of tropical cyclones during La Niña. The frequency of landfalling storms near Puerto Rico is about the same for La Niña and ENSO neutral years (when the relative frequency of La Niña and ENSO neutral years is taken into account). The strongest landfalling storms, on average, occurred in the ENSO Neutral years. So, the best possible scenario for Puerto Rico (at least regarding landfalling hurricanes) is an outlook for El Niño conditions during the Hurricane Season.
Sierra, Rafael*UMET, ;
The Impact of El Niño Transition in the Saliniy of Atlantic Ocean
Precipitation and salinity data over the Tropical Atlantic Ocean were compared during the month of June, in the summers of 2001 and 2002. The salinity data was evaluated at depths of 1m to 40m at representative coordinates, paying particular attention to density changes. These changes could be attributed to the warming of the Eastern Pacific Ocean in association with El Niño transition. This transition has become more noticeable in the last couple of months, as determined through the Madden-Julian Oscillation (MJO). Variations in the water temperatures have had an impact on the distribution of precipitation over the Pacific Ocean, which also had an indirect impact on the rainfall distribution over the Tropical Atlantic Ocean. This study quantifies the impact of the El Niño transition through the evaluation of the salinity and rainfall accumulation at selected observing stations. Research shows that subtle variations in water density/composition could have a detrimental impact on sea borne flora and fauna. Some of these, such as the phytoplankton and zooplankton, cannot tolerate drastic variations in the concentration of salt/minerals. It is because they lack effective mechanisms of defense to cope with these changes in density.