Defect-Seeded Atomic Layer Deposition of Metal Oxides on the Basal Plane of 2D Layered Materials

Atomic layer deposition (ALD) on mechanically exfoliated 2D layered materials spontaneously produces network patterns of metal oxide nanoparticles in triangular and linear deposits on the basal surface. The network patterns formed under a range of ALD conditions and were independent of the orientation of the substrate in the ALD reactor. The patterns were produced on MoS2 or HOPG when either tetrakis(dimethylamido)titanium or bis(ethylcyclopentadienyl)manganese were used as precursors, suggesting that the phenomenon is general for 2D materials. Transmission electron microscopy revealed the presence, prior to deposition, of dislocation networks along the basal plane of mechanically exfoliated 2D flakes, indicating that periodical basal plane defects related to disruptions in the van der Waals stacking of layers, such as perfect line dislocations and triangular extended stacking faults networks, introduce a surface reactivity landscape that leads to the emergence of patterned deposition

Fast seed histology protocols: Benzene derivatives-free vs xylene-dependent

Introduction. Seeds are complex structures that allow the biological and crop propagation of plants. Seed histology can be used for teaching, researching, and for pathological diagnostic. Histology protocols are commonly divided into 5 different stages: fixation, processing, cutting, staining, and mounting. Xylene is a dangerous reagent used during the processing, staining, and mounting of histological specimens that can contaminate the environment and is toxic for users. Objective. To compare two new protocols for seed histology accelerated with microwave, tested on seeds of economic importance species. Materials and methods. The experiments were done between January and May of 2022 at the Centro de Investigaciones en Granos y Semillas (CIGRAS) of the Universidad de Costa Rica. The compared protocols were: a benzene derivatives-free (BDF) and a xylene-dependent (XD). Seeds of Carica papaya L. (Caricaceae) var. Pococí, Coffea arabica L. (Rubiaceae) var. Obata, Glycine max L. (Fabaceae) var. CIGRAS-06, Phaseolus vulgaris L. (Fabaceae) var. Tayni, Oryza sativa L. (Poaceae) var. Lazarroz FL, and Zea mays L. (Poaceae) var. EJN-2 were used. Three technical replicates of five seeds of each species were tested with the XD and BDF protocols, on different days each replicate. Results. The photomicrographs obtained with both protocols showed that the samples maintained the morphology integrity of embryo, endosperm or cotyledons, and other seed structures. BDF and XD protocols produced seed histology slides and microphotographs. PAS-Coomassie Blue staining made a good differentiation of carbohydrates and proteins. Fastness of both protocols is a benefit compared with other protocols for plant histology that can take several days or even weeks. Conclusions. The BDF and XD protocols were suitable for seed histology analysis of bean, coffee, maize, papaya, and soybean, slides were obtained in less than 5 hours. BDF protocol is the first for plant tissue processing that does not use benzene derivatives and that uses paraffin as embedding medium.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro para Investigaciones en Granos y Semillas (CIGRAS

Formulación para tratamientos adecuados a la fibrosis quística utilizando árboles de decisión

La minería de datos como una herramienta científica, ha sido de gran importancia en muchas áreas del conocimiento, entre ellas la medicina. Ha tomado mucha fuerza en las últimas décadas gracias a la gran capacidad de manejo de datos importantes contenidos en una gran base de datos sin importar el tipo de investigación. Los pacientes con fibrosis quística debido a que su enfermedad tiene un número variado de síntomas y tratamientos aplicables; se buscan a partir de esta tecnología mejorar la calidad de vida de los pacientes que la padecen. Haciendo uso de las nuevas técnicas de la inteligencia artificial, se pueden resolver esta clase de problemas. Se busca que a partir de los árboles de decisión se logre dar un tratamiento adecuado para la problemática de los pacientes que sufren esta enfermedad. Se le dará explicación al uso de esta técnica aplicándola a esta enfermedad y se desarrollara un prototipo de la aplicación para que formule los tratamientos adecuados a los pacientes

Sistema de telemetría para el monitoreo y registro de las variables ambientales de un cultivo hidropónico

En Colombia el mal uso de las tierras para la plantación de diversos cultivos ha provocado el aumento de suelos erosionados, impidiendo la correcta producción de diversas frutas y vegetales, además de no permitir la producción de diversos productos agrícolas que sirvan para la exportación y mismo consumo del país, este factor se encuentra en aumento dado a la falta de nutrientes y minerales necesarios para cumplir con los consumidos por cada planta sembrada en estos terrenos. Por ende se busca la implementación nuevos métodos que permitan solucionar esta problemática. Los cultivos hidropónicos son cultivos que no se siembran en la tierra como es lo habitual, la siembra se realiza en agua, a la cual se le añaden los nutrientes necesarios para el cultivo… sin embargo requiere de constante vigilancia e intervención para que funcione. El proyecto propone como posible solución el diseño de un sistema de monitoreo y registro de las variables ambientales de un cultivo hidropónico, permita hacer la revisión del estado del cultivo por un medio web, además de poder obtener análisis de los datos para una correcta supervisión. El proyecto contara con varios desarrollos relacionados entre sí: Primero: Analizar las variables a ser medidas y realizar el diseño de un sistema de instrumentación y medida de cada variable. Segundo: Realizar el diseño de un sistema de comunicaciones entre el sistema de instrumentación y el sistema de registro. Tercero: Realizar el diseño de una interfaz web que permita la visualización y manejo de los datos adquiridos. Cuarto: Validar estadísticamente los datos adquiridos. Quinto: Realizar el diseño del prototipo de cultivo a ser censado

Education inequalities in Latin America and the Caribbean

Education is a crucial asset for a country’s economic prospects and for its inhabitants. In addition to its direct impact on growth via the accumulation of human capital, it is a critical ingredient in producing an informed citizenry, enhancing their ability to obtain and exert human and political rights and their facility to adapt to changing environments (generated by, e.g., technological or climatic change) among other benefits. In this chapter, we study education inequality in LAC (both in quantity and quality), assess how it emerges and amplifies or dampens existing inequalities, and examine the interaction of education inequality with other forms of inequality, primarily income and labor market outcomes. Our analysis is based on primary data from multiple sources

Embryo development in Carica papaya Linn

Proyecto interdisciplinarioPapaya (Carica papaya Linn.) is a tropical plant whose draft genome has been sequenced. Papaya produces large fruits rich in vitamins A and C and is an important cash crop in developing countries. Nonetheless, little is known about how the female gametophyte develops, how it is fertilized and how it develops into a mature seed containing an embryo and an endosperm. The Papaya female gametophyte displays a Polygonum-type architecture consisting of two synergid cells, an egg cell, a central cell, and three antipodal cells. Reports are available of the presumed existence of varieties in which cross fertilization is bypassed and autonomous development of embryos occurs (e.g., apomixis). In this study, we analyzed the development of female gametophytes in a commercial Hawaiian parental line and in the presumed apomictic Costa Rican line L1. Samples were collected before and after anthesis to compare the overall structure, size and transcriptional patterns of several genes that may be involved in egg and endosperm cell fate and proliferation. These genes were the putative papaya homologs of ARGONAUTE9 (AGO9), MEDEA (MEA), RETINOBLASTOMA RELATED-1 (RBR1), and SLOW WALKER-1 (SWA1). Our results suggest that its feasible to identify the contour of structural features of Polygonum-type development, and that in bagged female flowers of line L1 we might have observed autonomous development of embryo-like structures. Possible downregulation of papaya homologs for AGO9, MEA, RBR1 and SWA1 was observed in embryo sacs from line L1 before and after anthesis, which may suggest a tentative link between suspected apomixis and transcriptional downregulation of genes for RNA-directed DNA methylation, histone remodelers, and rRNA processing. Most notably, the large size of the papaya embryo sac suggests that it could be a cytological alternative to Arabidopsis thaliana for study. Significant variation in embryo sac size was observed between the varieties under study, suggesting wide differences in the genetic regulation of anatomical features.Universidad de Costa Rica/[736-B5-A13]/UCR/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM)UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de BiologíaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Jardín Botánico Lankester (JBL

Two-step BEC coming from a temperature dependent energy gap

We report the effects on the thermodynamic properties of a 3D Bose gas caused by a temperature dependent energy gap $\Delta (T)$ at the lower edge of the energy spectrum of the particles constituting the Bose gas which behaves like an ideal Bose gas when the gap is removed. Explicit formulae are given for the critical temperature, the condensate fraction, the internal energy and the isochoric specific heat, which are calculated for three different gaps that abruptly go to zero at temperature $T_B$, as well as for the damped counterparts whose drop to zero we have smoothed. In particular, for the undamped BCS (Bardeen, Cooper and Schrieffer) gap it is observed that the Bose-Einstein condensation (BEC) critical temperature $T_c$ is equal to that of the ideal Bose gas $T_0$, for all $T_B \leq T_0$; surprisingly, the condensate fraction presents two different filling rates of the ground state at $T_c = T_0$ and at $T_B < T_0$; while the specific heat shows a finite jump at $T_c$ as well as a divergence at $T_B$. Three-dimensional infinite Bose gas results are recovered when the temperature independent gap is either a constant or equal to zero.Comment: 10 pages, 17 figure

La concurrencia de proponentes en la subasta inversa

La tesis que se plantea en el presente artículo, tiene su origen en la interpretación de los principios de pluralidad de concurrentes y de economía, la cual pretende que la actividad contractual no sea el resultado de la improvisación y el desorden, sino que obedezca a una verdadera planeación para satisfacer necesidades de la comunidad. La ausencia de múltiples de oferentes en la subasta rompe en consecuencia con el principio de igualdad, y significaría la adopción de formas encubiertas de discriminación perturbadoras sustancialmente de los propósitos definidos

La Evaluación de los Aprendizajes en Inglés como Lengua Extranjera desde una Perspectiva Fenomenológica

La evaluación de los aprendizajes siempre ha tenido un rol importante dentro de los procesos pedagógicos. Recientemente, investigaciones nacionales e internacionales han investigado el fenómeno de la evaluación en el aula