Sequential treatment of 2,3-dichloropropene with magnesium and n-BuLi generates the operational equivalent of 1,3-dilithiopropyne, which upon treatment with aldehydes or ketones, produces the corresponding alkoxy lithium acetylide intermediates. Reaction of this alkoxide with tosyl chloride, and t-BuLi produces 1-substituted, or 1,1-disubstituted 1,3-enynes in a one-pot reaction. When this lithium acetylide intermediates, obtained by this procedure, were used to perform palladium-catalyzed cross-coupling reactions, followed by addition of thionyl chloride and pyridine, 1,4-disubstituted or 1,1,4-trisubstituted 1,3-enynes were obtained in a one-pot protocol.
This study explores the assessments made by the inhabitants of eight Latin American countries regarding the current state of the environment, at a local, national and global scale, and how it is perceived looking ahead to the future. It also examines the assignment of responsibility in the future management of the environment. A total of 944 people took part in the study from the eight participating countries, men and women over the age of 18 with different levels of education. The study uses the Environmental Futures Scale to which two relevant items have been added to assess the environment in the region, as well as the Assignment of Environmental Responsibility Scale. The results show differences between the countries, although in general they are pessimistic regarding the current and future state of the environment at the local, national and global level, with the exception of Brazil. In general, and with the exception of Brazil, in the countries surveyed, people assign a high level of responsibility to external social agents at the different levels, increasing their judgement of external responsibility at the national and global levels of analysis. The implications of these findings for environmental policy and education in the countries of this region are also discussed.
Sequential fragmentation/transport theory (SFT) was used to analyze tephra deposits of the two main recent explosive eruptions from Irazú volcano, the 1723 and 1963-65 events. The final results provide a new way to analyze fragmentation and transport processes, which fix well with the field observations made by Alvarado (1993). A new way to process fragmentation/transport revealed 4 phi ranges that can be associated to initial volcanic fragmentation. The SFT fragmentation coefficient method is expanded to include all 5 subpopulations, allowing to compare the 1723 and 1963-65 events. SFT interpretation of 1723 eruptions is in good agreement with the volcanological description of such explosive events, whereas SFT points to a more complex 1963-65 eruption, probably due to volcanic recycling and sedimentary reworking as it is observed in the field.
The Sequential fragmentation/transport theory (SFT), applied to grain size analysis of the deposits from the 1723 and 1963-65 Irazú volcano eruptions, showed an appreciable number of cases with positive dispersion, usually associated to particle aggregation. A new fractal dimension is proposed here to explain them as a secondary fragmentation process. This leads to a new fractal model of volcanic eruptive process, where the Hurst Coefficient and the power law exponent are included. Dispersion values near zero suggest the existence of lava pools. Results deduced from the model agree well with field observations.
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