Revista de Química. Vol. 22 Núm. 1-2 (2008)
URI permanente para esta colecciónhttps://hdl.handle.net/20.500.14657/185289
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Ítem Texto completo enlazado Arsenic geochemistry and its impact in public health: the Bangladesh case(Pontificia Universidad Católica del Perú, 2008) Sánez, JuanConsidered the king of poisons, arsenic occurs naturally in the environment being present in air, soil, water and food. Its presence in drinking water is of global concern. Initial chronic exposure is manifested by skin lesions. Additionally, arsenic consumption impairs certain visceral organs: bladder, liver, prostate, etc. More over, arsenic is a recognized carcinogenic substance.When in Bangladesh started the program to lead safe drinking water in the 60’s, they never imagined the catastrophic consequences. Water wells were drilled in the whole country. The arsenic problem was recognized recently in the 90’s. In order to understand the nature of arsenic in the environment and how it could possibly reach groundwater in Bangladesh, this work explains some chemical characteristics of arsenic, the geological formation of the basin, and its mobility.The origin of arsenic contamination in the Bangladesh Delta is due to the geologic nature of the basin rather than the possibility of an arsenic rich mineral. The profile of sediments shows that the Delta is not homogeneous, but rather heterogeneous even in closer areas. The driving process for arsenic mobility is mainly the reduction by iron oxyhydroxides coupled with organic matter, including other factors such as particle size, depth, morphology, metal content, as wellÍtem Texto completo enlazado Métodos para determinar la configuración absoluta de una molécula(Pontificia Universidad Católica del Perú, 2008) Cedrón, Juan CarlosMethods for the assignment of the absolute configuration of an organic molecule: The assignment of the absolute configuration of chiral molecules represents a great challenge for organic chemists. There are several techniques in order to establish it, and they are described in this work, as well as examples of how they can be applied in the assignment of the absolute configuration of natural products.Ítem Texto completo enlazado Perfil Nacional para Evaluar la Infraestructura Nacional para la Gestión de Sustancias Químicas: resumen ejecutivo(Pontificia Universidad Católica del Perú, 2008) Gamboa, NadiaEste documento fue elaborado por el Proyecto Plan Nacional de Implementación del Convenio de Estocolmo Sobre Contaminantes Orgánicos Persistentes en el Perú (GEF-SENASA-CONAM-DIGESA-PNUMA) y ha sido transcrito para adaptarse a esta publicación. La correspondencia debe ser dirigida a cop@digesa.minsa.gob.pe; mquinones@digesa.minsa.gob.pe o visitar www.copsperu.org.pe; www.digesa.minsa.gob.pe; www.senasa.gob.pe; www.conam.gob.pe.Ítem Texto completo enlazado Protein directed evolution(Pontificia Universidad Católica del Perú, 2008) Laos, RobertoDirected evolution allows us to explore protein functionalities not required in the natural environment. It mimics natural genetic processes and selective pressures. This approach is used when the molecular basis is not completely understood and rational design is a difficult task. This approach consists of serial cycles of consecutive diversification and selection which eventually lead to the accumulation of beneficial mutations. Here are presented two cases where directed evolution is used to modify two different proteins: Taq polymerase, enzyme used for DNA extension in PCR, and the LacI repressor protein which regulates gene expression on E.coli.Ítem Texto completo enlazado Pulsos láser de femtosegundo en espectroscopía y microscopía de dos fotones(Pontificia Universidad Católica del Perú, 2008) Coello, Yves; Fantus, MarcusFemtosecond laser pulses in two-photon spectroscopy and microscopy: The application of shaped ultrashort laser pulses (≤10fs) in two-photon spectroscopy and microscopy carried out in our group is described, highlighting the advantages and requirements of this approach. In addition, a brief description of pulse shaping, phase distortions experienced by femtosecond laser pulses and how to correct these distortions using a pulse shaper is also presented.