Simón Bolívar University

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.

Breaking of Water-in-Crude Oil Emulsions. 5. Effect of Acid-Alkaline Additives on the Performance of Chemical Demulsifiers

Abstract: The objective is to understand the effects of organic acid and amine additives on the performance of commercial demulsifiers in breaking water-in-crude-oil (W/O) emulsions, according to the proportional regime test developed in previous articles. Both hydrophilic (ethylamine and acetic acid) and hydrophobic (hexanoic acid and hexylamine) species were tested, and all were found to exhibit different effects. The water-soluble species have essentially no effect, despite a change in aqueous phase pH. Hexanoic acid was found to increase the stability of the W/O emulsions, whereas the hexylamine was found to reduce it. Explanations of the effect of these additives on the interfacial formulation are proposed.

Path-based systems to guide scientists in the maze of biological data sources

Abstract: Fueled by novel technologies capable of producing massive amounts of data for a single experiment, scientists are faced with an explosion of information which must be rapidly analyzed and combined with other data to form hypotheses and create knowledge Today, numerous biological questions can be answered without entering a wet lab Scientific protocols designed to answer these questions can be run entirely on a computer Biological resources are often complementary, focused on different objects and reflecting various experts' points of view Exploiting the richness and diversity of these resources is crucial for scientists However, with the increase of resources, scientists have to face the problem of selecting sources and tools when interpreting their data In this paper, we analyze the way in which biologists express and implement scientific protocols, and we identify the requirements for a system which can guide scientists in constructing protocols to answer new biological questions We present two such systems, BioNavigation and BioGuide dedicated to help scientists select resources by following suitable paths within the growing network of interconnected biological resources

Size and shape changes in the skull accompanying speciation of South American spiny rats (Rodentia: Proechimys spp.)†

Abstract: Size and shape changes in the skull of South American spiny rats Proechimys spp. were investigated using geometric morphometrics. Six species were studied (P. guairae, P. poliopus, P. trinitatis, P. canicollis, P. mincae and Proechimys sp.) using 12 populations from Venezuela and Colombia. Proechimys poliopus, P. guairae and Proechimys sp. have undergone recent speciation coupled with chromosomal rearrangements. The separate analysis of size and shape showed that the only sexually dimorphic character is size; P. mincae is the smallest species and Proechimys sp. the largest. The populations are all recognizable by their shape, and populations of the same species share a common kind of shape modification. The prevalent non-uniform nature of morphological change in the skull shows how the various structures, such as those involved with audition, feeding and olfaction, are modified differently among species. Consequently, the modification of these different structures over a long time could reflect a progressive diversification of the microniche of each species.