RESUMO
Chrysobalanus icaco es una planta que pertenece a la familia Chrysobalanaceae. En Tabasco, Mexico, esta planta se distribuye en los municipios de la costa. La finalidad de esta investigacion fue la caracterizacion cromosomica de dos fenotipos con color de fruto rosa y purpura mediante tincion convencional. Con tal fin, se recolectaron frutos maduros en la comunidad de Penjamo, Paraiso, Tabasco. Las semillas se dejaron germinar por 30 dias a una temperatura constante de 30 °C. Se utilizaron raicillas de 1,00 cm de longitud, las cuales fueron sometidas a hidrolisis acida y posterior tincion con orceina. Se fotografiaron 295 metafases y se midieron los cromosomas de 35 placas metafasicas del fenotipo purpura y 30 del fenotipo rosado. Ambos fenotipos presentaron 18 cromosomas pequenos, los cuales se ordenaron en nueve pares homologos segun su tamano relativo. No se observaron diferencias morfologicas ni numericas entre los cariotipos de ambos fenotipos. Ademas la prueba de t-Student (α=0,05) revelo que no se encuentran diferencias significativas entre los complementos cromosomicos de ambos fenotipos.
Chrysobalanus icaco is a plant that belongs to the Chrysobalanaceae family. In Tabasco, Mexico, this plant is distributed in the municipalities of the coastline. The main purpose of this research was to characterize the chromosomal structure of phenotypes with pink and purple fruits by the use of conventional staining. To this end, mature fruits were collected in the community of Penjamo, Paraiso, Tabasco. Seeds were allowed to germinate for 30 days at a constant temperature of 30° C. Roots of 1.00 cm in length were subjected to acid hydrolysis and subsequent staining with orcein. A total of 295 metaphases were photographed and chromosomes of 35 metaphases of the purple phenotype and 30 of the pink phenotype were measured. Both phenotypes presented 18 small chromosomes, which were ordered in nine homologous pairs according to their relative size. No morphological or numerical differences were observed between the karyotypes of both phenotypes. In addition, the t-Student (α=0.05) test did not reveal significant differences between the chromosomes complements of both phenotypes.
RESUMO
In this Letter, we stress the essential role played by gas inertia in the breakup of gas bubbles. Our results reveal that, whenever the gas to liquid density ratio Lambda=rhog/rhol is different from zero, tiny satellite bubbles may be formed as a result of the large gas velocities that are reached close to pinch-off. Moreover, we provide a closed expression for the characteristic satellite diameter, which decreases when decreasing Lambda and which shows order of magnitude agreement with the micron-sized satellite bubbles observed experimentally.
RESUMO
Analytical considerations and potential-flow numerical simulations of the pinch-off of bubbles at high Reynolds numbers reveal that the bubble minimum radius, rn, decreases as tau proportional to r2n sqrt[1lnr2n], where tau is the time to break up, when the local shape of the bubble near the singularity is symmetric. However, if the gas convective terms in the momentum equation become of the order of those of the liquid, the bubble shape is no longer symmetric and the evolution of the neck changes to a rn proportional to tau1/3 power law. These findings are verified experimentally.
RESUMO
Here we report a simple microfluidics phenomenon which allows the efficient mass production of micron size gas bubbles with a perfectly monodisperse and controllable diameter. It resorts on a self-excited breakup phenomenon (which locks at a certain frequency) of a short gas microligament coflowing in a focused liquid stream. In this work, we describe the physics of the phenomenon and obtain closed expressions for the bubble diameter as a function of the liquid and gas properties, geometry, and flow parameters, from a large set of experimental results.