Analytical obtention of eigen-energies for lens-shaped quantum dot with finite barriers

The bound states of a particle in a lens-shaped quantum dot with finite confinement potential are obtained in the envelope function approximation. The quantum dot has circular base with radius $a$ and maximum cap height $b$, and the effective mass of the particle is considered different inside and outside the dot. A 2D Fourier expansion is used in a semi-sphere domain with infinite walls which contains the geometry of the original potential. Electron energies for different values of lens deformation $b/a$, lens radius $a$ and barrier height $V_o$ are calculated. In the very high confinement potential limit, the results for the infinite barrier case are recovered.Comment: 5 pages, 3 figures, accepted for publication in The European Physical Journal

Alternativas de cultivos intercalados para el establecimiento de plantaciones de cítricos en el Piedemonte del departamento del Meta

Uno de los limitantes para la plantación de los huertos citrícolas en Colombia es el alto costo del establecimiento y el periodo improductivo en sus fases inciales. En condiciones del departamento del Meta, tomando como referencia árboles injertados en madarina, la entrada en producción después del transplante es: cuatro años para naranja, seis o más para tangelo, cinco para mandarina y dos para lima.Naranja-Naranja dulce - Citrus sinensis. P

Análisis y ejecución de estrategias en la industria de sensores mediante la simulación CAPSIM

Documento en el que se muestra el trabajo realizado en la dirección de una empresa de la industria de sensores dentro del simulador de negocios Capsim. Se presenta un análisis de la industria de los sensores, se describe la empresa en la que se trabajó, las estrategias de negocio y el proceso de su implementación, así como los resultados finales

In vitro gastrointestinal digestion of microencapsulated extracts of Flourensia cernua, F. microphylla, and F. retinophylla

Recently, some species of the genus Flourensia have been identified by their potential health effects (e.g. anti-inflammatory and apoptotic). Encapsulation of plant extracts is a process that can allow an adequate dosage administration, as well as to protect bioactive compounds and improve their controlled release in the gastrointestinal (GI) system. Therefore, the aims of this work were: to microencapsulate the ethanol extracts of F. cernua, F. microphylla, and F. retinophylla; and to evaluate the controlled release of the microencapsuled extracts in an in vitro GI system. Leaves of Flourensia spp. were collected in wild sites of Coahuila State, and the ethanol extracts were obtained by the Soxhlet method. The encapsulation was performed by the gelation technique, using alginate. The microcapsules formed were characterized in terms of total phenol content (Folin-Ciocalteu method), antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic) diammonium acid (ABTS), and the ferric reducing antioxidant power (FRAP) assays, scanning electron microscopy (SEM), and thermal analysis, and in vitro GI digestion. The microcapsules were found to have spherical-shape and a micro-scale dimension in the range of 2.168.8??m. Also, the built of microcapsules was confirmed by the appearance of an exothermic peak centered at 600?°C in the DSC analysis. F. microphylla noted for its strong antioxidant activity, even in its encapsulated form. In the gastric system the extracts of fresh microcapsules were released from 7.7% to 14.5%, while values of 26.5% to 53.3% were observed for those dried. For the intestinal system, the higher release was observed for dried microcapsules (59.9% to 78.4%) than for those fresh (26.3% to 30.2%). Thus, it was demonstrated that the alginate microcapsule protected the extracts until they were delivered to the target site in the GI model, and this effect was better with the dried microcapsules of Flourensia spp. This study would set the guide for the application of Flourensia spp. extracts in order to take advantage of their benefits to human health.Author G.N. Puente Romero thanks Mexican Science and Technology Council (CONACYT, Mexico) for MSc fellowship support. Authors would like to thank to María Guadalupe Moreno Esquivel, Edith E. Chaires Colunga, Olga L. Solís Hernández, and M. Leticia Rodríguez González of the Phytochemistry Laboratory from Universidad Autónoma Agraria Antonio Narro, for their support in the lab experiments.info:eu-repo/semantics/publishedVersio

Extreme Saharan dust event over the southern Iberian Peninsula in september 2007: active and passive remote sensing from surface and satellite

This study investigates aerosol optical properties during the extreme Saharan dust event detected from 3 to 7 September 2007 over Granada, southern Iberian Peninsula, with both active and passive remote sensing instrumentation from surface and satellite. The intensity of the event was visualized on the aerosol optical depth series obtained by the sun-photometer Cimel CE 318-4 operated at Granada in the framework of AERONET from August 2004 until December 2008 (level 2 data). A combination of large aerosol optical depth (0.86–1.50) at 500 nm, and reduced Angström exponent (0.1–0.25) in the range 440–870 nm, was detected on 6 September during daytime. This Saharan dust event also affected other Iberian Peninsula stations included in AERONET (El Arenosillo and Évora stations), and it was monitored by MODIS instrument on board Aqua satellite. Vertically resolved measurements were performed by a ground-based Raman Lidar and by CALIPSO satellite. During the most intense stage, on 6 September, maximum aerosol backscatter values were a factor of 8 higher than other maxima during this Saharan dust event. Values up to 1.5×10−2 km−1 sr−1 at 355 and 532 nm were detected in the layer with the greatest aerosol load between 3–4 km a.s.l., although aerosol particles were also detected up to 5.5 km a.s.l. In this stage of the event, dust particles at these altitudes showed a backscatter-related Angström exponent between –0.44 and 0.53 for the two spectral intervals considered. The results from different measurements (active/passive and ground-based/satellite) reveal the importance of performing multi-instrumental measurements to properly characterize the contribution of different aerosol types from different sources during extreme events. The atmospheric stabilization effect of the aerosol particles has been characterized by computing the solar heating rates using SBDART code.This work is supported by the Spanish Ministry of Education project CGL2007-66477-C02-01 and CSD2007-00067, by Andalusian Regional Government projects P06-RNM-01503 and P08-RNM-3568, and by the EARLINETASOS project (EU Coordination Action, contract No. 025991 (RICA))

Characterization of Oct4-GFP transgenic mice as a model to study the effect of environmental estrogens on the maturation of male germ cells by using flow cytometry

Oct4 is involved in regulation of pluripotency during normal development and is down-regulated during formation of postnatal reservoir of germ cells. We propose thatOct4/GFP transgenic mouse, which mimics the endogenous expression pattern of Oct4, could be used as a mammalian model to study the effects of environmental estrogens on the development of male germ cells. Oct4/GFP maturation profile was assessed during postnatal days -PND- 3, 5, 7, 10, 14 and 80, using flow cytometry. Then, we exposed pregnant mothers to 17a-ethinylestradiol (EE2) from day post coitum (dpc) 5 to PND7. Percentage of Oct4/GFP-expressing cells and levels of expression of Oct4/GPF were increased in PND7 after EE2 exposure. These observations were confirmed by analysis of GFP and endogenous Oct4 protein in the seminiferous tubules and by a reduction in epididymal sperm count in adult mice. We introduced Oct4/ GFP mouse together with flow cytometry as a tool to evaluate changes in male germ cells development.Agencia Nacional de Investigación e InnovaciónFONCyT (Fondo para la InvestigaciónCientífica y Tecnológica de la Agencia Nacional de PromociónCientífica y Tecnológica, ANPCyT, Argentina)FOCEM (MERCOSUR Structural Convergence Fund), COF 03/11CONICET (becas doctoral y postdoctoral

Eficacia de la alta presión hidrostática como tratamiento cuarentenario para mejorar la calidad de los frutos del mango infestados por la mosca de la fruta Mexicana Anastrepha ludens

High hydrostatic pressure (HPP) has been reported as an alternative quarantine process in fruits infested by Ceratitis capitata Wiedemann, Rhagoletis indifferens Curran and Cydia pomonella (L.). In Mexico and other Latin-American countries, the Mexican fruit fly Anastrepha ludens Loew is one of the most important insects infesting mangoes, citrus, and other fruits. The present study aimed to determine the effect of pressure level and time on the survival of eggs and larvae of the Mexican fruit fly. Eggs and larvae were pressurized at 25, 50, 75, 100, or 150 MPa for 0, 5, 10 or 20 min at 25 8C. Ripe and green mangoes were also pressurized under the same conditions. On pressurized eggs of 1, 2, 3, and 4 days old, their ability to hatch was recorded. On pressurized first, second and third instars, the percentage of survival was registered. Furthermore, third instars were studied for their ability to pupate and to develop adults. The results showed that although most of eggs and larvae died at pressures lower than 100 MPa, some of them were able to survive even at 150 MPa, and a few third instars were able to pupate and to develop to adulthood. Green mangoes were affected by pressures above 75 MPa but they were more resistant than ripe mangoes. HPP treatments seem to be feasible as a quarantine process for mangoes; however, more studies, such as combining HPP with temperature treatments, are needed in order to decrease the pressure level to avoid fruit damageLa alta presión hidrostática ha sido descrita como un proceso de cuarentena alternativa en frutas infestadas por Ceratitis capitata Wiedemann, Rhagoletis indifferens Curran y Cydia pomonella (L.). En México y otros países Latinoamericanos, la mosca de la fruta mexicana Anastrepha ludens Loew es uno de los más importantes insectos que infestan los mangos, cítricos y otras frutas. El presente estudio tuvo como meta determinar el efecto del nivel de presión y tiempo sobre la supervivencia de huevos y larvas de la mosca de la fruta mexicana. Huevos y larvas se presurizaron a 25, 50, 75, 100, y 150 MPa durante 0, 5, 10, y 20 min a 25 8C. Mangos maduros y verdes también se presurizaron bajo las mismas condiciones. En huevos presurizados de uno, dos, tres y cuatro días de vida, se registró su capacidad para eclosionar. En primera, segunda y tercera etapa larvaria presurizada, el porcentaje de supervivencia también se registró. Además, en la tercera etapa larvaria se estudió su capacidad para salir de la crisálida y desarrollar adultos. Los resultados mostraron que aunque la mayoría de los huevos y larvas murieron a presiones por debajo de 100 MPa, algunos de ellos fueron capaces de sobrevivir aun a 150 MPa, y unas pocas larvas de tercera etapa fueron capaces de salir de la crisálida y desarrollar adultos. Los mangos verdes se vieron afectados por las presiones por encima de 75 MPa pero fueron más resistentes que los mangos maduros. Los tratamientos de alta presión hidrostática parecen ser un proceso viable como método cuarentenario para mangos, sin embargo, se necesitan más estudios tales como la combinación de alta presión hidrostática junto con tratamientos térmicos para disminuir los niveles de presión y evitar daños en la frutaThe authors are grateful to Fondo Mixto CONACYT –Gobierno del Estado de Tamaulipas for the financial support of this work (Project TAMPS-2003-C02-15), to CONACYT for the scholarship granted to author Hugo Ernesto CandelarioS