Unraveling reaction mechanisms by means of Quantum Chemical Topology Analysis

A chemical reaction can be understood in terms of geometrical changes of the molecular structures and reordering of the electronic densities involved in the process; therefore, identifying structural and electronic density changes taking place along the reaction coordinate renders valuable information on reaction mechanism. Understanding the atomic rearrangements that occur during chemical reactions is of great importance, and this perspective aims to highlight the major developments in quantum chemical topology analysis, based on the combination of electron localization function and catastrophe theory as useful tools in elucidating the bonding and reactivity patterns of molecules. It reveals all the expected, but still ambiguous, elements of electronic structure extensively used by chemists. The chemical bonds determine chemical reactivity, and this technique offers the possibility of their visualization, allowing chemists to understand how atoms bond, how and where bonds are broken/formed along a given reaction pathway at a most fundamental level, and so, better following and understanding the changes in the bond pattern. Their results clearly herald a new era, in which the atomic imaging of chemical bonds will constitute a new method for examining chemical structures and reaction mechanisms. The important feature of this procedure is that in practice the scope of its values is system-independent. In addition, from a practical point of view, it is cheap to calculate and implement because wave functions are the required input, which are easily available from standard calculations. To capture these results two reaction mechanisms: isomerization of C(BH)2 carbene and the thermal cycloheptatriene-norcaradiene isomerizations have been selected, indicating both the generality and utility of this type of analysis

A bonding evolution analysis for the thermal Claisen rearrangement: an experimental and theoretical exercise for testing the electron density flow

A comprehensive theoretical investigation of the thermal Claisen rearrangement of allyl vinyl ether (AVE) to allylacetaldehyde has been carried out. We present the use of the electron localization function (ELF) to monitor the bonding evolution aspects in the course of this thermal rearrangement and the results are compared with a photo-impulsive process where instantaneous vibration frequencies are monitored [Phys. Chem. Chem. Phys., 2011, 12, 5546-5555]. Our results reveal an asynchronous electron density rearrangement inasmuch that the breaking of the C3-O bond and the formation of the C1- C5 do not take place simultaneously. We also demonstrate how the bonding evolution brings about the natural appearance of the curly arrows representing the electronic flow in molecular rearrangements. This holds the key to gaining an unprecedented insight into the mapping of the electron density flow while the bonds change throughout the reaction progress

Pseudo-nitzschia australis blooms are not always toxic

Postprin

Curly arrows, electron flow, and reaction mechanisms from the perspective of the bonding evolution theory

Despite the usefulness of curly arrows in chemistry, their relationship with real electron density flows is still imprecise, and even their direct connection to quantum chemistry is still controversial. The paradigmatic description – from first principles – of the mechanistic aspects of a given chemical process is based mainly on the relative energies and geometrical changes at the stationary points of the potential energy surface along the reaction pathway; however, it is not sufficient to describe chemical systems in terms of bonding aspects. Probing the electron density distribution during a chemical reaction can provide important insights, enabling us to understand and control chemical reactions. This aim has required an extension of the relationships between the concepts of traditional chemistry and those of quantum mechanics. Bonding evolution theory (BET), which combines the topological analysis of the electron localization function (ELF) and Thom’s catastrophe theory (CT), provides a powerful method that offers insight into the molecular mechanism of chemical rearrangements. In agreement with the laws of physical and aspects of quantum theory, BET can be considered an appropriate tool to tackle chemical reactivity with a wide range of possible applications. In this work, BET is applied to address a long-standing problem: the ability to monitor the flow of electron density. BET analysis shows a connection between quantum mechanics and bond making/forming processes. Likewise, the present approach retrieves the classical curly arrows used to describe the rearrangements of chemical bonds and provides detailed physical grounds for this type of representation. We demonstrate this procedure using the test set of prototypical examples of thermal ring apertures, and the degenerated Cope rearrangement of semibullvalene

AUDITORÍA DE GESTIÓN AL PROCESO DE EMISIÓN Y RECAUDACIÓN DE IMPUESTOS A LOS PREDIOS URBANOS Y RÚSTICOS DEL GOBIERNO AUTÓNOMO DESCENTRALIZADO MUNICIPAL DEL CANTÓN MONTÚFAR, PARA EL PERIODO COMPRENDIDO ENTRE EL 1 DE ENERO AL 31 DE DICIEMBRE DEL 2014

El presente trabajo de investigación está direccionado a la ejecución de unaauditoría de gestión al proceso de emisión y recaudación de impuestos a lospredios urbanos y rústicos del Gobierno Autónomo Descentralizado Municipaldel Cantón Montúfar, para el periodo comprendido entre el 01 de eneroal 31 de diciembre del 2014.En la metodología que se utiliza se describe el tipo de investigación y losmétodos que son aplicados de acuerdo al problema investigado, también sedefine las modalidades y se explica él por qué de la selección, tomando encuenta que la metodología que se utiliza en el desarrollo del presente trabajoinvestigativo.Con la aplicación de cuestionarios del control interno en la Entidad se pudoevaluar el riesgo de control como un riego alto y nivel de confianza bajo,por lo que se diseñó un programa de auditoría a la medida y se obtuvo loshallazgos descritos en el presente trabajo, la auditoría se ejecutó siguiendolas normas de la auditoría gubernamental emitido por la Contraloría Generaldel Estado

BPM para la gestión de procesos del instituto de posgrado de la Universidad Técnica del Norte

Implantar el módulo de gestión de procesos, utilizando la librería BPMN-JS en el Instituto de Posgrado de la Universidad Técnica del Norte.El Instituto de Posgrado de la Universidad Técnica del Norte cuenta con procesos administrativos y académicos que no están integrados al sistema informático integrado universitario, lo que genera demora en el tiempo de respuesta y un inadecuado seguimiento de los mismos; además se evidencia dificultad en la comunicación entre las dependencias, ocasionando escasa regularización en los procesos. El objetivo del presente estudio es implantar el módulo de gestión de procesos, utilizando la librería BPMN-JS y APEX en el Instituto de Posgrado de la Universidad Técnica del Norte que permita organizar los procesos académicos y administrativos relacionados a matriculación y titulación. El tipo de investigación empleada como base fundamental fue la revisión bibliográfica sobre estudios realizados a la aplicación de BPM en Instituciones de Educación Superior, en cuanto a las técnicas de recolección de información se aplicó encuestas realizadas al personal académico y administrativo del Instituto de Posgrado, entrevistas al Director de informática y el análisis de contenido. Los resultados de la integración de la Herramienta APEX con la librería BMPN-JS en el sistema informático integrado universitario (SIIU) de la Universidad Técnica del Norte permite al personal Administrativo, Docente y Estudiantes del Instituto de Posgrado conocer de manera ágil las actividades y tareas de los procesos, optimizando tiempos de respuesta en la gestión

Management aspects related to tourism management and waste management in lodging companies of Puerto Quito, Ecuador

El presente artículo reflexiona sobre la gestión turística y el manejo de residuos (elementos sólidos) en el cantón Puerto Quito, especialmente en algunos sitios de alojamiento locales. Igualmente, permite determinar las alternativas de concientización ambiental y otras actividades que se pueden desarrollar para un mejor manejo de los residuos, considerando que Puerto Quito (provincia de Pichincha, Ecuador) posee diversidad de atractivos naturales relevantes: cascadas, flora y fauna tropicales nativas, lugares para realizar deportes extremos, así como sitios de hospedaje con elementos de esparcimiento interno, que se podrían ver afectados si no se mejoran las actividades de gestión actuales de los residuos. Se trabajó con tres empresas vinculadas a la operatividad turística dentro del cantón Puerto Quito y el tipo de manejo de residuos que llevan a cabo. Se aplicaron entrevistas estructuradas para sistematizar la información. Las personas entrevistadas concuerdan que el servicio actual de recolección municipal en general no abastece a la producción de residuos generados en las Hosterías, igualmente mencionan que se debe colocar más contenedores internos y aumentar la cultura ambiental en habitantes locales y en turistas para colocar los residuos en los recipientes correctos; también hace falta proveer de mayor información a estos dos grupos en torno a actividades como la reutilización, la recuperación, el reciclaje; rompiendo el esquema tradicional de “recolección - disposición final”. El Municipio en conjunto con las empresas turísticas deberán elaborar y ejecutar continuamente diferentes programas y actividades de participación en temas de concientización ambiental para los habitantes locales y para visitantes y turistas con respecto al tema de manejo de residuos sólidos.This article reflects on tourism management and waste management (solid elements) in the Puerto Quito canton (Pichincha province, Ecuador), especially in some local accommodation sites. Likewise, it allows to determine the alternatives of environmental awareness and other activities that can be developed for better waste management, considering that Puerto Quito has a diversity of relevant natural attractions: waterfalls, native tropical flora and fauna, places for extreme sports, as well as hosting sites with elements of internal recreation, which could be affected if the current waste management activities are not improved. We worked with three companies linked to tourism operations within the Puerto Quito canton and the type of waste management they carry out. Structured interviews were applied to systematize the information. The people interviewed agree that the current municipal collection service in general does not cater to the production of waste generated in the Hosterias, they also mention that more internal containers must be placed and the environmental culture must be increased in local inhabitants and tourists to place the waste in the right containers; It is also necessary to provide more information to these two groups on activities such as reuse, recovery, recycling; breaking the traditional "collection - final disposal" scheme. The Municipality, together with the tourism companies, must continuously develop and execute different programs and activities for participation in environmental awareness issues for local inhabitants and for visitors and tourists regarding the solid waste management issue

Mesoscale dynamics and niche segregation of two Dinophysis species in Galician-Portuguese coastal waters

Blooms of Dinophysis acuminata occur every year in Galicia (northwest Spain), between spring and autumn. These blooms contaminate shellfish with lipophilic toxins and cause lengthy harvesting bans. They are often followed by short-lived blooms of Dinophysis acuta, associated with northward longshore transport, at the end of the upwelling season. During the summers of 1989 and 1990, dense blooms of D. acuta developed in situ, initially co-occurring with D.acuminata and later with the paralytic shellfish toxin-producer Gymnodiniumcatenatum. Unexplored data from three cruises carried out before, during, and following autumn blooms (13⁻14, 27⁻28 September and 11⁻12 October) in 1990 showed D. acuta distribution in shelf waters within the 50 m and 130 m isobaths, delimited by the upwelling front. A joint review of monitoring data from Galicia and Portugal provided a mesoscale view of anomalies in SST and other hydroclimatic factors associated with a northward displacement of the center of gravity of D. acuta populations. At the microscale, re-examination of the vertical segregation of cell maxima in the light of current knowledge, improved our understanding of niche differentiation between the two species of Dinophysis. Results here improve local transport models and forecast of Dinophysis events, the main cause of shellfish harvesting bans in the most important mussel production area in Europe.project ASIMUTH (EC) FP7-SPACE-2010-1 EU EAPA_182/201info:eu-repo/semantics/publishedVersio

Fine scale physical-biological interactions during a shift from relaxation to upwelling with a focus on Dinophysis acuminata and its potential ciliate prey

Wind reversals and quick transitions from relaxation to upwelling in coastal areas cause major changes in water column structure, phytoplankton distribution and dominance, and rates of physiological processes. The cruise "ASIMUTH-Rías" (17–21 June 2013) was carried out in the Galician Rías and adjacent shelf, at the time of a DSP outbreak, to study small-scale physical processes associated with late spring blooms of "D. acuminata" and accompanying microzooplanktonic ciliates with the overall objective of improving predictive models of their occurrence. The cruise coincided with the initiation of an upwelling pulse following relaxation and deepening of a previously formed thin layer of diatoms. A 36-h cell cycle study carried on 18–20 June showed the vertical excursions of the thin layer, mainly delimited by the 13.5–14 °C isotherms and turbulence levels (ε) of 10−8–10−6 m2 s −3, as well as marked changes in phytoplankton composition (increased density and dominance of diatoms). There was no evidence of daily vertical migration of D. acuminata, which remained in the top layer during the cycle study, but the opposite was observed in the ciliate populations. Dinophysis and its potential prey (Mesodinium species) cell maxima overlapped after midday, when the ciliate moved to the surface, suggesting an “ambush” strategy of Dinophysis to catch prey. A remarkable decline (from 0.65 to 0.33 d−1) in division rates (µ) of D. acuminata was associated with increased turbulence (ε 2°C in about 8 h). In contrast, high division rates (µmin ∼ 0.69 d−1) persisted at a mid-shelf station where environmental conditions below the mixed layer were more stable. The onset of upwelling pulses appears to have a double negative effect on the net growth of Dinophysis populations: a direct physical effect due to advective dispersion and an indirect effect, decreased division rates. The latter would be caused by the rapid cooling of the mixed layer, and the increased turbulence at the surface resulting in shear stress to the cells. The short-term impact of upwelling pulses (and the winds promoting it) on the physiology of "Dinophysis" and its ciliate prey, and the role of mid-shelf populations of "Dinophysis" as a relatively undisturbed reservoir for the inoculation of subsequent blooms are discussed.European Commission | Ref. EC FP7-SPACE-2010-1, n. 261860Ministerio de Economía | Ref. CTM2016-75451-C2-2-RInterreg Atlantic Area | Ref. EAPA_182/2016Comisión Nacional de Ciencia y Tecnología Research (CONICYT), Chile | Ref. PAI79160065Comisión Nacional de Ciencia y Tecnología Research (CONICYT), Chile | Ref. REDES17010