Polarization, Isopotential Maps and Tunneling in Guanine, Cytosine, and Tautomeric Forms

We have used the CNDO/2-CI method to calculate the isopotential maps for the fundamental state and the direction of the polarizations corresponding to several singlet transitions in the molecules of guanine, cytosine and tautomeric forms. We have also calculated the times for proton tunneling and equilibrium constants between both conformers corresponding to the fundamental and some excited states. The results have been compared with the available experimental data.Publicado on line en 2014.Facultad de Ciencias Exacta

The adenine and thymine molecules: some excited singlet and triplet levels of the normal and tautomeric forms

The shape of the barrier for the H transfer between the normal and tautom eric forms have been determ ined for the adenine and thymine molecules. The correlations for several singlet and triplet states has been calculated using the CNDO/2-CI method. The relative stability between both conformations and the agreement with some experimental values is also discussed.Publicado on line en 2014.Facultad de Ciencias Exacta

The tautomeric conformers for the molecules of guanine and cytosine: some remarks about their stability

In this paper we seek to determine the shape of the barrier between the normal and tautom eric conformers for some excited singlet and triplet states in the molecules of guanine and cytosine. The molecules are considered isolated and a particular movement of the H atom is analysed. The semi-empirical CNDO/2-CI has been used. The calculated results are compared with the available experimental data.Publicado on line en 2014.Facultad de Ciencias Exacta

Polarization, Barriers and Tunneling Times of Some Tautomers of Adenine and Thymine

The polarization of the radiation involved in some transitions is analysed for the normal and tautomeric forms of adenine and thymine. Tunneling times for some barriers previously reported [1] and equilibrium constants between two isomers for some excited states are also given. The calculations have been made with the CNDO/2-CI method and the results compared with the available experimental data.Publicado on line en 2014.Facultad de Ciencias Exacta

Some Theoretical Considerations About the Excited Singlet and Triplet States of Diformamide and N-Methyl Diformamide

The molecules of diformamide and N-methyl diformamide are analysed using the CNDO-CI method. Several excited singlet and triplet states corresponding to the three possible conformers and charge distributions are discussed.Publicado on line en 2014.Facultad de Ciencias Exacta

Molecular Orbital Theory of the Electronic Structure of Organic Compounds IV : A CNDO/S-CI SCF MO Study on the Lower Electronic States of Large Molecules. Singlet-triplet Transitions of Dioxodiazacycloalkanes

The semiempirical molecular orbital CNDO/S-CI spectral parameterization has been used to elucidate the lower triplet electronic states of a series of dioxodiazacycloalkanes. The 1³B₂(nₒπ*) and 1³A₂ (nₒπ*) triplet spectroscopic states involve intramolecular charge transfer from the oxygen to the carbon atom of the carbonyl group, which is supported by electron density calculations of these excited states. The solvation energy was incorporated in the calculations.Publicado on line en 2014.Facultad de Ciencias Exacta

Análisis forense de un motor diesel

Este trabajo busca determinar las causas que generaron una serie de grietas longitudinales sobre la pared interna de una camisa de un motor de combustión interna diesel V12 turbocargado, el cual se utilizaba para bombeo de crudo. La falla de este componente se descubrió al realizarse una inspección de mantenimiento en la cual se encontró agua en el interior de la camisa, retirándose el motor de servicio e iniciando un estudio forense de la falla. El análisis de la superficie interna de la camisa reveló una elevada presencia de cavidades ubicadas en la zona del punto muerto superior, las cuales actúan como concentradores de esfuerzos, facilitando la nucleación de grietas

Molecular Orbital Theory of the Electronic Structure of Organic Compounds I. Dioxodiazacycloalkanes

The stability of some heterocyclic compounds derived from the condensation of succinic and glutaric anhydrides with aliphatic diamines is compared using calculated values for the total energies. Further, some results derived from the electronic population analysis and the available experimental data are used to give information about the corresponding electronic structure. The CNDO/2 and INDO methods have been used for the calculations.Publicado on line en 2014.Facultad de Ciencias Exacta

Challenges and opportunities in rapid disaster research: lessons from the field in New Mexico and Vanuatu

Rapid research is essential to assess impacts in communities affected by disasters, particularly those communities made “hard-to-reach” due to their active marginalization across history and in contemporary practices. In this article, we describe two rapid research projects developed to assess needs for and experiences of communities hard-hit by disasters. The first is a project on the COVID-19 pandemic in southern New Mexico (USA) that was developed to provide information to local agencies that are deploying programs to rebuild and revitalize marginalized communities. The second is a project on population displacement due to a volcanic eruption in Vanuatu, a lower-middle income country in the South Pacific, with mental and physical health outcomes data shared with the Vanuatu Ministry of Health. We describe the similar and unique challenges that arose doing rapid research in these two different contexts, the potential broader impacts of the research, and a synthesis of lessons learned. We discuss the challenges of rapidly changing rules and regulations, lack of baseline data, lack of survey instruments validated for specific populations and in local languages, limited availability of community partners, finding funding for rapid deployment of projects, rapidly training and working with research assistants, health and safety concerns of researchers and participants, and communicating with local and international partners. We also specifically discuss how we addressed our own personal challenges while also conducting time-intensive rapid research. In both studies, researchers shared results with governmental and non-governmental partners who may use the data to inform the design of their own relief programs. While different in context, type of disaster, and research strategy, our discussion of these projects provides insights into common lessons learned for working with communities at elevated risk for the worst outcomes during disasters, such as the need for flexibility, compromise, and good working relationships with community partners