Facultad de Ciencias Exactas y Naturales

URI permanente para esta comunidadhttp://10.0.96.45:4000/handle/11056/14053

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Biogenic silica-based microparticles obtained as a sub-product of the nanocellulose extraction process from pineapple peels
(Nature Publishing Group, 2018-07-10) Corrales-Ureña, Yendry R.; Villalobos-Bermúdez, Carlos; Pereira, Reinaldo; Camacho, Melisa; Estrada, Eugenia; Argüello-Miranda, Orlando; Vega-Baudrit, Jose R.
Silica in plant tissues has been suggested as a component for enhancing mechanical properties, and as a physical barrier. Pineapples present in their shell and bracts rosette-like microparticles that could be associated to biogenic silica. In this study, we show for the first time that silica-based microparticles are co-purified during the extraction process of nanocellulose from pineapple (Ananas comosus). This shows that vegetable biomass could be an underappreciated source, not only for nanocellulose, but also for a highly valuable sub-product, like 10 µm biogenic rosette-like silica-based microparticles. The recovery yield obtained was 7.2 wt.%; based on the dried initial solid. Due to their size and morphology, the microparticles have potential applications as reinforcement in adhesives, polymer composites, in the biomedical field, and even as a source of silica for fertilizers.
Contrasting patterns of leaf trait variation among and within species during tropical dry forest succession in Costa Rica
(Nature Publishing Group, 2018-01-10) Derroire, Géraldine; Powers, Jennifer S.; Hulshof, Catherine M.; Cárdenas Varela, Luis E.; Healey, John R.
A coordinated response to environmental drivers amongst individual functional traits is central to the plant strategy concept. However, whether the trait co-ordination observed at the global scale occurs at other ecological scales (especially within species) remains an open question. Here, for sapling communities of two tropical dry forest types in Costa Rica, we show large dierences amongst traits in the relative contribution of species turnover and intraspecic variation to their directional changes in response to environmental changes along a successional gradient. We studied the response of functional traits associated with the leaf economics spectrum and drought tolerance using intensive sampling to analyse inter- and intra-specic responses to environmental changes and ontogeny. Although the overall functional composition of the sapling communities changed during succession more through species turnover than through intraspecic trait variation, their relative contributions diered greatly amongst traits. For instance, community mean specic leaf area changed mostly due to intraspecic variation. Traits of the leaf economics spectrum showed decoupled responses to environmental drivers and ontogeny. These ndings emphasise how divergent ecological mechanisms combine to cause great dierences in changes of individual functional traits over environmental gradients and ecological scales.
Recovery of acetate by anion exchange with consecutive CO2-expanded methanol desorption: A model-based approach
(Elsevier BV, 2018-04-07) Cabrera-Rodrígueza, Carlos I.; Cartin-Caballeroa, Carlos M.; Platarou, Evgenia; de Weerd, Florence A.; van der Wielena, Luuk A.M.; Straathof, Adrie J.J.
Production of bio-based acetate is commonly hindered by the high costs of the downstream processing. In this paper, a model is developed to describe a new method that recovers acetate salts using anion exchange resins, and subsequently desorbs and upgrades them using CO2-expanded alcohol. The model consists of equilibrium parameters for both the adsorption and desorption step. The calculated parameters are: for the adsorption − =− KCl 0.125 Ac , − = − K 0.206 Cl HCO3 and KOV HAc , = 0.674 mol / kgresin mol / kgsolution , and for the desorption − = − pK 3.71. MeCO Ac 3 The maximum experimental concentration of acetic acid obtained in CO2-expanded methanol is 0.427 mol/kg (20 g/ LMeOH) at an operating pressure of 31 bar. The model represents the expected trends for all species, and can be used to design a multicolumn system for the recovery and upgrading of carboxylates
Spontaneous spawning, ontogeny and growth in captivity of Cynoscion squamipinnis
(Universidad de Costa Rica, 2016-09-03) Boza Abarca, Jorge
The croakers or drums are commercial species, which have been overfished in the Nicoya Gulf, Costa Rica. This study aimed to describe, for the first time, the reproduction and the ontogeny of weakfish, Cynoscion squamipinnis in captivity, in order to perform restocking and mariculture projects. Wild fish (n= 6, 1-2 Kg) were captured and maintained in the Estación de Biología Marina Juan Bertoglia Richards (Puntarenas, Costa Rica) for a two years period (October 2006- December 2008). During this period, maturation stage was monitored periodically by cannula samples in the females (n= 3) and gentle massage in males (n= 3). All fish were stocked in an 18 t tank, with aeration, 33-35 ups of salinity, and a constant temperature (29 ± 1 °C). The spawning period occurred from January to March 2009, producing 162 000 eggs in three spontaneous spawns. The fertilization percentage was 50-60%, and survival after hatching was 60-85%. The egg diameter was 0.852 mm (Standard deviation (SD)= 0.039), and oil drop of 0.269 mm (SD= 0.016). In the embryonary development, the first mitotic division (MD) was observed one hour after spawning (has), the second MD was 1:30 has, the third MD was 2:00 has, the fourth MD was 2:30 has, and fifth MD at 3:00 has. Morule was observed 3:30 has, the blastule 4:30 has, the gastrule 8:30 has, C shape at 10:00 has, and C shape at 12:00 has. After 19 has hatching larvae occurred. The total length (TL) of the larvae was 2.234 mm (SD= 0.122), and the nothochordial length (NL) was 2.179 mm (SD= 0.119). Preflexion stage was observed 49 has, flexion stage was 11 days after spawn (das) (3.767 mm LT (SD= 0.209)), and postflexion stage was 14 das (4.015 mm LT (SD= 0.302)). After 45 das, the juvenile weights 3.68 g (SD= 1.09). Hatch time of the weakfish larvae was minor than of others croaker species. The stages times of embrionary development were a little different from others croaker species, and probably respond to genetic characteristics of each species and the eggs incubation temperature. The spontaneously spawning without broodstock hormonal applications, and the juveniles production in captivity showed that weakfish is a potential species for restocking programs and mariculture projects. © 2016 Universidad de Costa Rica. All Rights Reserved. RESUMEN Las corvinas son especies de interés comercial que han sido sobre explotadas en el Golfo de Nicoya, Costa Rica. El objetivo de este estudio fue describir por primera vez, el desove espontáneo y la ontogenia de las larvas de la corvina aguada Cynoscion squamipinnis en cautiverio, con el fin de realizar repoblamiento y proyectos de maricultura. Reproductores silvestres (n= 6, 1-2 Kg), fueron capturados y mantenidos en la Estación de Biología Marina Juan Bertoglia Richards (Puntarenas, Costa Rica) por un periodo de dos años (octubre 2006-diciembre 2008). Durante este periodo, el estado de madurez de las hembras (n= 3) fue registrado mediante muestras de cánula y los machos (n= 3) mediante masaje abdominal. Todos los reproductores fueron colocados juntos en un tanque de 18 t, con aireación, a una salinidad entre 33-35 ups y expuestos a una temperatura constante (29 ± 1 °C). De enero a marzo 2009 ocurrió un periodo de desove espontáneo, obteniéndose 162000 huevos en tres desoves. El porcentaje de fertilización fue de 50-60 %, y la supervivencia después de la eclosión fue entre 60-85 %. El diámetro de los huevos fue de 0.852 mm (Desviación Estándar= 0.039), con una gota de aceite de 0.269 mm (DE= 0.016). En el desarrollo embrionario, la primera división mitótica ocurrió una hora después del desove (hdd), la segunda división 1:30 hdd, la tercera división 2 hdd, la cuarta división a las 2:30 hdd, y la quinta 3:00 hdd. La mórula fue observada a las 3:30 hdd, la blástula a las 4:30 hdd, la gástrula a las 8:30 hdd, la forma C a las 10:00 hdd, y la forma S ocurrió de las 10-19 hdd. La eclosión ocurrió 19 hdd. La larva midió 2.234 mm (DE= 0.122) de longitud total (LT), y 2.179 mm (DE= 0.119) de longitud notocordial (LN). La preflexión inició 49 hdd, la flexión 11 días después del desove (ddd) (3.767 mm LT, DE= 0.209), y la postflexión a los 14 ddd (4.015 mm LT, DE= 0.302). A los 45 ddd, los juveniles pesaron 3.68 g (DE= 1.09). El tiempo de eclosión de las larvas de la corvina aguada fue menor al de otras especies de corvina. Los tiempos de formación en las etapas embrionarias difirieron poco con respecto a los tiempos observados para otras especies de corvinas. Las diferencias observadas con respecto a otras especies, probablemente responden a las características genéticas propias de cada especie y a la temperatura de incubación de los huevos. La obtención de desoves espontáneos sin aplicaciones hormonales a los reproductores, y la producción de juveniles en cautiverio demostraron que la corvina aguada puede ser onsiderada en programas de repoblamiento y proyectos de maricultura.

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