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Mora J.R.,Agricultural University of Ecuador | Mora J.R.,Venezuelan Institute for Scientific Research | Lezama J.,University of the East Venezuela | Cordova-Sintjago T.C.,University of Florida | Chuchani G.,Venezuelan Institute for Scientific Research
Molecular Physics | Year: 2015

The mechanisms of the gas-phase thermal decomposition of bicyclo[2.2.1]heptadiene and 3,7,7-trimethylbicyclo[2.2.1]hept-2-ene were examined by density functional theory calculations with the hybrid functionals: B3LYP, CAM-B3LYP, MPW1PW91, and PBEPBE. Reasonable agreements were found between theoretical and experimental values with the B3LYP hybrid functional. Three molecular concerted pathways for bicyclo[2.2.1]heptadiene decomposition are proposed. The retro-Diels-Alder (retro-DA) pathway yields cyclopentadiene and acetylene through a nearly synchronous transition state structure (Sy=0.97). The other two reaction channels are stepwisewith a common step with the formation of the intermediate bicyclo[4.1.0] heptadiene. This reaction is dominated by C-C bond breaking leading to the methylene migration by an early transition state in the reaction coordinate (Sy = 0.91). The rearrangements of the latter intermediate producing toluene were also studied. The retro-DA elimination of 3,7,7-trimethylbicyclo[2.2.1]hept-2-ene gives 1,5,5-trimethyl-cyclopenta-1,3-diene in a less synchronous process (Sy = 0.77). This fact may be due to the electronic effects of the methyl substituent. The latter product is unstable and undergoes methyl migrations to give a more stable isomer 1,2,3-trimethylcyclopenta-1,3-diene. The stepwise mechanism for the retro-DA reaction through a biradical intermediate appears to be unfavourable because the barrier is bigger than that for the concerted reaction. © 2015 Taylor & Francis. Source


Blandon-Diaz J.U.,National University of Agriculture at Nicaragua | Blandon-Diaz J.U.,Swedish University of Agricultural Sciences | Forbes G.A.,International Potato Center | Andrade-Piedra J.L.,CIP | Yuen J.E.,Agricultural University of Ecuador
Plant Disease | Year: 2011

In this study, the adequacy of the late blight simulation model LATEBLIGHT (version LB2004) was evaluated under Nicaraguan conditions. During 2007 to 2008, five field experiments were conducted in three potato-production regions in northern Nicaragua. Two susceptible ('Cal White' and 'Granola') and one resistant ('Jacqueline Lee') potato cultivars were evaluated without use of fungicides and with three application intervals (4, 7, and 14 days) of the fungicide chlorothalonil. The simulation model was considered adequate because it accurately predicted high disease severity in susceptible cultivars without fungicide protection, and demonstrated a decrease in the disease progress curves with additional fungicide applications, similar to that observed in the plots. The model also generally predicted inadequate fungicide control, even with a 4-day spray interval, which also occurred in the field. Lack of adequate fungicide protection would indicate the need for cultivars with higher levels of durable resistance, and that farmers should consider more effective fungicides applications (higher dosages or different chemistries) if susceptible cultivars are used. © 2011 The American Phytopathological Society. Source


Mora J.R.,Agricultural University of Ecuador | Mora J.R.,Venezuelan Institute for Scientific Research | Lezama J.,University of the East Venezuela | Cordova-Sintjago T.C.,Florida College | Chuchani G.,Venezuelan Institute for Scientific Research
Molecular Physics | Year: 2015

The mechanisms of the gas-phase thermal decomposition of bicyclo[2.2.1]heptadiene and 3,7,7-trimethylbicyclo[2.2.1]hept-2-ene were examined by density functional theory calculations with the hybrid functionals: B3LYP, CAM-B3LYP, MPW1PW91, and PBEPBE. Reasonable agreements were found between theoretical and experimental values with the B3LYP hybrid functional. Three molecular concerted pathways for bicyclo[2.2.1]heptadiene decomposition are proposed. The retro-Diels–Alder (retro-DA) pathway yields cyclopentadiene and acetylene through a nearly synchronous transition state structure (Sy = 0.97). The other two reaction channels are stepwise with a common step with the formation of the intermediate bicyclo[4.1.0] heptadiene. This reaction is dominated by C–C bond breaking leading to the methylene migration by an early transition state in the reaction coordinate (Sy = 0.91). The rearrangements of the latter intermediate producing toluene were also studied. The retro-DA elimination of 3,7,7-trimethylbicyclo[2.2.1]hept-2-ene gives 1,5,5-trimethyl-cyclopenta-1,3-diene in a less synchronous process (Sy = 0.77). This fact may be due to the electronic effects of the methyl substituent. The latter product is unstable and undergoes methyl migrations to give a more stable isomer 1,2,3-trimethylcyclopenta-1,3-diene. The stepwise mechanism for the retro-DA reaction through a biradical intermediate appears to be unfavourable because the barrier is bigger than that for the concerted reaction. © 2015 Taylor & Francis Source


Freile J.F.,Fundacion Numashir | Salas J.A.,University of Guayaquil | Solano-Ugalde A.,Fundacion Imaymana | Navarrete R.,Agricultural University of Ecuador
Check List | Year: 2012

We report the first confirmed evidence of a feral introduced population of Brotogeris versicolorus (Statius Müller, 1776) in Guayaquil city, Ecuador, as part of the World Parrot Count led by City Parrots. A total of 216 individuals were counted, at two places within the city, but no direct evidence of breeding was found. A previously unpublished photograph suggesting nesting activity is also presented, along with brief comments on previous and additional observations and the conservation implications of this recently established feral species. © 2012 Check List and Authors. Source


Carina V.T.,University las Fuerzas Armadas | Emilia M.M.,University las Fuerzas Armadas | Miguel U.S.,Agricultural University of Ecuador | Ortiz D.R.,University las Fuerzas Armadas | And 3 more authors.
Journal of Applied Pharmaceutical Science | Year: 2016

The effect of the co-inoculation of arbuscular mycorrhizal fungi (AMF) and Azospirillum on micro-propagated banana seedlings development during their adaptation phase was determined. At the time of transplanting, banana seedlings were inoculated with an indigenous mycorrhizal inoculum containing 10 spores/g at four doses: 0, 50, 100 and 200 g. Seventy days after fungal inoculation, 20 ml of Azospirillum in four concentrations (0, 106, 107 and 108 CFU/ml) were applied. Finally, after 98 days from the start of the experiment a second dose (40 ml) of Azospirillum in the concentrations mentioned above was inoculated. Plants were harvested 5 months after transplanting and the growth and nutritional parameters were evaluated. The analysis of the data showed that banana plants co-inoculated with 200 g of AMF and 1.5E8 CFU/ml of Azospirillum presented greater development, an increase of 7 times in height, 4 times in perimeter, 16 times in leaf area, 12 times in aerial biomass, and 8 times in root biomass relative to control plants. The results achieved were due to synergism between fungus-bacteria when inoculated at higher doses, with lower doses stimulating growth is minimal. The co-inoculation in high doses demonstrates adequate support and cooperative effect between HMA and Azospirillum crops. In addition, co-inoculation promotes optimal nutritional status because microorganisms allowed plants achieve greater absorption of phosphorus and nitrogen relative to those treated with single inoculation and the control. © 2016 Villarreal Tania Carina et al. Source

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