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Institution

Simón Bolívar University

EducationCaracas, Venezuela
About: Simón Bolívar University is a education organization based out in Caracas, Venezuela. It is known for research contribution in the topics: Population & Crystallization. The organization has 5912 authors who have published 8294 publications receiving 126152 citations.


Papers
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Journal ArticleDOI
TL;DR: In this article, Fourier transform IR spectroscopy was used to quantify the conversion of different functional groups, and these conversions could be used to infer the type of reactions that took place.
Abstract: The curing process was studied for a trifunctional epoxy resin, triglycidyl-p-aminophenol, using the hardener 4,4′-diaminodiphenylsulfone. Two curing cycles were carried out: one following the manufacturer's guidelines (2 h at 80°C, 1 h at 100°C, 4 h at 150°C, and 24 h at 200°C) and another proposed in this study, in which the two stages at low temperatures were excluded. Fourier transform IR spectroscopy was used to quantify the conversion of different functional groups (primary amine, secondary amine, epoxide, hydroxyl and ether functional groups), and these conversions could be used to infer the type of reactions that took place. These results allowed us to analyze the evolution of the curing process over time and the influence of the curing cycle. Furthermore, the enthalpy of the curing process was determined using differential scanning calorimetry, and from this the thermal conversion for the whole process was evaluated. By taking into account the autocatalytic kinetic model, the rate constants were evaluated. The glass-transition temperatures were also estimated by applying different curing cycles to the resin. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1524–1535, 2005

45 citations

Journal ArticleDOI
TL;DR: The knowledge and useful applications of various fungi by the Hoti, a recently contacted Native American society inhabiting the Sierra Maigualida region of the Venezuelan Amazon, were reported in this paper.
Abstract: This paper reports on the knowledge and useful applications of various fungi by the Hoti, a recently contacted Native American society inhabiting the Sierra Maigualida region of the Venezuelan Amazon. At least 31 folk taxa of fungi are esteemed as sources of nutrition, powerful media for hunting magic, protective charms against black magic, human medicinal agents, or body adornments. Even though the results presented here probably do not exhaust the total number of species known and used by them, they nevertheless suggest that the Hoti constitute one of the rare mycophilic societies in the Venezuelan Amazon. Further research is needed in order to obtain a more complete picture of the complexity of humanfungi relationships in this society.

45 citations

Journal ArticleDOI
TL;DR: The synthetic two-component pheromone is approximately 60 times more attractive than the female-produced blend and might facilitate the control of this pest.
Abstract: Five candidate pheromone components were identified by analyzing pheromone gland extracts by gas chromatography (GC), coupled GC-electroantennographic detection (EAD), and coupled GC-mass spectrometry (MS): (E)-11-hexadecenol(E11–16 : OH), (Z)-11-hexadecenol (Z11–16 : OH),(E)-11-hexadecenal, (E)-11-hexadecenyl acetate, and (Z)-3,(Z)-6,(Z)-9-tricosatriene (Z3,Z6,Z9–23 : Hy). In electroantennogram (EAG) recordings, synthetic E11–16 : OH elicited stronger antennal responses at low doses than other candidate pheromone components. Field tests demonstrated that synthetic E11–16 : OH as a trap bait was effective in attracting males, whereas addition of Z11–16 : OH inhibited the males' response. Z3,Z6,Z9–23 : Hy strongly enhanced attractiveness of E11–16 : OH, but was not attractive by itself. A pheromone blend with synergistic behavioral activity of an alcohol (E11–16 : OH) and hydrocarbon (Z3,Z6,Z9–23 : Hy) component is most unusual in the Lepidoptera. The synthetic two-component pheromone is approximately 60 times more attractive than the female-produced blend and might facilitate the control of this pest.

44 citations

Journal ArticleDOI
TL;DR: In this paper, a set of experimental tests were conducted to investigate the influence of the angle formed between the major axis of the expanded metal and the compressive load, and three types of collapse response were mainly observed depending on the orientation of the axes.
Abstract: Expanded metal sheeting is widely used around the world for catwalks, granting, and decorative purposes. In the literature, little information can be found regarding the behavior of structural elements made of expanded metal. This paper is aimed at studying the axial collapse of squared and round tubes made of expanded metal sheeting under compressive loading. When expanding the metal a diamond-like cell pattern is formed in the metal sheets, then these patterns are characterised by two geometrical axes. A set of experimental tests was conducted to investigate the influence of the angle formed between the major axis of the expanded metal and the compressive load. From the results, three types of collapse response were mainly observed depending on the orientation of the axes: (1) Mode 1 characterised by a plastic collapse mechanism; (2) Mode 2 local buckling of the individual cells; and (3) Mode 3 global buckling of the tube walls.

44 citations


Authors

Showing all 5925 results

NameH-indexPapersCitations
Franco Nori114111763808
Ignacio Rodriguez-Iturbe9633432283
Ian W. Hamley7846925800
Francisco Zaera7343219907
Thomas G. Habetler7339520725
Douglas L. Jones7051221596
I. Taboada6634613528
Enrique Herrero6424211653
Rudi Studer6026819876
Alejandro J. Müller5842012410
David Padua5824311155
Rudolf Jaffé5818210268
Luis Balicas5732814114
Volker Abetz5538611583
Ananias A. Escalante511608866
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20232
202220
2021286
2020384
2019340
2018312