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Dehydration of alcohols in the presence of copper(II) sulfate has been analyzed computationally. Density functional theory (DFT) calculations on selected alcohols indicate that this reaction can take place via two possible mechanisms: (a) concerted - although asynchronous - type II dyotropic reactions, or (b) stepwise E1-like processes, in which cleavage of the C-O bond occurs in the first step, followed by syn proton elimination. Our calculations show the relationship between the initial alcohol structure and the preferred mechanism, which is a type II dyotropic reaction for primary alcohols, whereas a stepwise process is the favored one when stable carbocation intermediates are energetically accessible. The dehydration of dehydrolinalool (2,7-dimethyl-6-en-1-yn-3-ol, DHL) to yield different alkenes of interest in the fragrance industry is discussed as a case study of its regiochemistry.
ABSTRACT
Resumo Fundamento A pandemia de COVID-19 interferiu na prestação de atendimento a doenças cardiovasculares na América Latina. No entanto, o efeito da pandemia nos volumes de procedimentos cardíacos diagnósticos ainda não foi quantificado. Objetivo Avaliar (1) o impacto de COVID-19 nos volumes de diagnóstico cardíaco na América Latina e (2) determinar sua relação com a incidência de casos de COVID-19 e as medidas de distanciamento social. Métodos A International Atomic Energy Agency realizou uma pesquisa mundial avaliando mudanças nos volumes diagnósticos cardíacos decorrentes da COVID-19. Foram obtidos os volumes diagnósticos cardíacos dos locais participantes para março e abril de 2020 e comparados com março de 2019. Foram coletados dados de distanciamento social a partir dos Relatórios de mobilidade da comunidade de Google e a incidência de COVID-19 por país a partir de Our World in Data. Resultados Foram realizadas pesquisas em 194 centros que realizam procedimentos diagnósticos cardíacos, em 19 países da América Latina. Em comparação com o mês de março de 2019, os volumes dos procedimentos diagnósticos cardíacos diminuíram 36% em março de 2020 e 82% em abril de 2020.As maiores reduções ocorreram em relação aos testes de estresse ecocardiográfico (91%), testes ergométricos de esteira (88%) e escore de cálcio por tomografia computadorizada (87%), com pequenas variações entre as sub-regiões da América Latina. As mudanças em padrões de distanciamento social (p < 0,001) estavam mais fortemente associadas com a redução do volume do que a incidência de COVID-19 (p = 0,003). Conclusões A COVID-19 foi associada a uma redução significativa de procedimentos diagnósticos cardíacos na América Latina, a qual foi mais relacionada ao distanciamento social do que ao aumento da incidência da COVID-19. São necessários melhor equilíbrio e timing de medidas de distanciamento social e planejamento para manter o acesso ao atendimento médico durante um surto pandêmico, especialmente em regiões com alta mortalidade cardiovascular.
Abstract Background The COVID-19 pandemic has disrupted the delivery of care for cardiovascular diseases in Latin America. However, the effect of the pandemic on the cardiac diagnostic procedure volumes has not been quantified. Objective To assess (1) the impact of COVID-19 on cardiac diagnostic volumes in Latin America and (2) determine its relationship with COVID-19 case incidence and social distancing measures. Methods The International Atomic Energy Agency conducted a worldwide survey assessing changes in cardiac diagnostic volumes resulting from COVID-19. Cardiac diagnostic volumes were obtained from participating sites for March and April 2020 and compared to March 2019. Social distancing data were collected from Google COVID-19 community mobility reports and COVID-19 incidence per country from the Our World in Data. Results Surveys were conducted in 194 centers performing cardiac diagnostic procedures, in 19 countries in Latin America. Procedure volumes decreased 36% from March 2019 to March 2020, and 82% from March 2019 to April 2020. The greatest decreases occurred in echocardiogram stress tests (91%), exercise treadmill tests (88%), and computed tomography calcium scores (87%), with slight variations between sub-regions of Latin America. Changes in social distancing patterns (p < 0.001) were more strongly associated with volume reduction than COVID-19 incidence (p = 0.003). Conclusions COVID-19 was associated with a significant reduction in cardiac diagnostic procedures in Latin America, which was more related to social distancing than to the COVID-19 incidence. Better balance and timing of social distancing measures and planning to maintain access to medical care is warranted during a pandemic surge, especially in regions with high cardiovascular mortality.
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Fundamentos: La Directiva 98/8/CE armoniza y regula en el mercado europeo la autorización y registro de biocidas y establece un periodo de 14 años para la revisión de sustancias activas. Este trabajo analiza los cambios más relevantes producidos en el registro de biocidas desinfectantes registrados desde la publicación de la Directiva. Métodos: La información se ha obtenido del registro de Biocidas publicado en la web del Ministerio de Sanidad, Política Social e Igualdad a mayo de 2010. Se ha utilizado una hoja de cálculo Excel para el volcado y tratamiento de los datos. Resultados: Existen 1.575 biocidas desinfectantes (1137 formulados y 438 ingredientes activos técnicos) registrados en España destinados a uso ambiental y en industria alimentaria. Los formulados están compuestos por 56 sustancias activas que están siendo estudiadas para su inclusión en la lista comunitaria de sustancias autorizadas. El 54% de los formula-dos están registrados como bactericida-fungicida, el 79% se aplican por contacto, el 42% son compuestos de amonio cuaternario y el 67.9% están elaborados con una sola sustancia activa. Respecto a su peligrosidad el 45.3% son corrosivos, el 25.7% irritantes, el 9.8% nocivos, el 1.1 % tóxicos y el 33.1% son peligrosos para el medio ambiente. Conclusiones: El registro de biocidas español se adecua a lo establecido en la Directiva cancelando los registros que contienen sustancias no incluidas en la lista. El 58% de las sustancias activas de uso ambiental y el 76,4% de uso en industria alimentaria en revisión en Europa se encuentran autorizadas en España(AU)
Background: Directive 98/8/EC harmonizes and regulates in the European market authorization and registration of biocides and establishes a period of 14 years for review of active substances. This study analyzes the most significant changes produced in the registry of biocides used as disinfectants registered since the publication of the Directive. Method: Information was obtained from the registry of biocides published in the website of the Ministry of Health, Social Policy and Equality in May 2010. We used an Excel data base for the dump and data processing. Results: There are 1575 biocides with intended use as environmental and food area disinfectants registered in Spain (1137 formulas and 438 active ingredients). Formulas are composed of 56 active sustances which are being assessed for their inclusion in the Community list of authorized substances. 54% of the formulas are registered as both bactericide and fungicide, 79% are contact disinfectants, 42% of the formulas correspond to those composed of quaternary ammonium compounds and 67.9% are made with a single active substance. Regarding hazardous properties 45.3% are corrosive, 25.7% irritant, 9.8% harmful, 1.1% toxic , and 33.1% are dangerous to the environment. Conclusions: The Spanish registry of biocides has complied with the provisions of the Directive cancelling the registrations of the formulas containing substances not included in the list. Of all the substances which are under review in Europe, 58% of environmental disinfectants and 76.4% of food area disinfectants are authorized in Spain(AU)