Toward mass production of microtextured microdevices: linking rapid prototyping with microinjection molding

The possibility of manufacturing textured materials and devices, with surface properties controlled from the design stage, instead of being the result of machining processes or chemical attacks, is a key factor for the incorporation of advanced functionalities to a wide set of micro and nanosystems. Recently developed high-precision additive manufacturing technologies, together with the use of fractal models linked to computer-aided design tools, allow for a precise definition and control of final surface properties for a wide set of applications, although the production of larger series based on these resources is still an unsolved challenge. However, rapid prototypes, with controlled surface topography, can be used as original masters for obtaining micromold inserts for final large-scale series manufacture of replicas using microinjection molding. In this study, an original procedure is presented, aimed at connecting rapid prototyping with microinjection molding, for the mass production of two different microtextured microsystems, linked to tissue engineering tasks, using different thermoplastics as ultimate materials.

Glycerin and lecithin inclusion in diets for brown egg-layinghens: Effects on egg production and nutrient digestibility

The effects of the inclusion of raw glycerin (GLYC) and lecithin in the diet on egg production,egg quality and total tract apparent retention (TTAR) of dietary components was studied inbrown egg-laying hens from 23 to 51 wk of age. The experimental design was completelyrandomized with six diets combined as a 2 × 3 factorial with two levels of GLYC (0 vs.70 g/kg) and three animal fat to lecithin ratios (40:0, 20:20 and 0:40 g/kg). Each treatmentwas replicated eight times and the experimental unit was a cage with ten hens. Productionwas recorded by replicate every 28-d period and cumulatively. For the entire experiment,the inclusion of GLYC in the diet hindered feed conversion ratio per kilogram of eggs (2.071vs. 2.039; P < 0.05) but did not affect any of the other production or egg quality traits studied.The replacement of animal fat by lecithin (40:0, 20:20 and 0:40 g/kg) increased egg weight(60.1, 60.7 and 61.8 g, respectively; P < 0.001) and egg mass production (56.8, 57.5 and58.8 g/d, respectively; P < 0.01) and improved yolk color as measured by the DSM colorfan (9.2, 9.2 and 9.5, respectively; P < 0.001) and feed conversion ratio per kilogram of eggs(2.072, 2.068 and 2.027, respectively; P < 0.05). Feed intake, egg production and body weightgain, however, were not affected. The inclusion of GLYC in the diet did not affect nutrientretention but lecithin inclusion improved TTAR of dry matter (P < 0.05), organic matter(P < 0.05), ether extract (P < 0.001) and gross energy (P < 0.001). In summary, the inclusionof 70 g glycerol/kg diet hindered feed conversion ratio per kilogram of eggs but did notaffect any other production or digestibility trait. The replacement of animal fat by lecithinimproved egg weight, egg yolk color and nutrient digestibility. Consequently, lecithin canbe used as a lipid source in laying hen diets with beneficial effects on egg production

Regional and seasonal patterns of litterfall in tropical South America

The production of aboveground soft tissue represents an important share of total net primary production in tropical rain forests. Here we draw from a large number of published and unpublished datasets (n = 81 sites) to assess the determinants of litterfall variation across South American tropical forests. We show that across old-growth tropical rainforests, litterfall averages 8.61±1.91Mgha?1 yr?1 (mean±standard deviation, in dry mass units). Secondary forests have a lower annual litterfall than old-growth tropical forests with a mean of 8.01±3.41Mgha?1 yr?1. Annual litterfall shows no significant variation with total annual rainfall, either globally or within forest types. It does not vary consistently with soil type, except in the poorest soils (white sand soils), where litterfall is significantly lower than in other soil types (5.42±1.91Mgha?1 yr?1). We also study the determinants of litterfall seasonality, and find that it does not depend on annual rainfall or on soil type. However, litterfall seasonality is significantly positively correlated with rainfall seasonality. Finally, we assess how much carbon is stored in reproductive organs relative to photosynthetic organs. Mean leaf fall is 5.74±1.83Mgha?1 yr?1 (71% of total litterfall). Mean allocation into reproductive organs is 0.69±0.40Mgha?1 yr?1 (9% of total litterfall). The investment into reproductive organs divided by leaf litterfall increases with soil fertility, suggesting that on poor soils, the allocation to photosynthetic organs is prioritized over that to reproduction. Finally, we discuss the ecological and biogeochemical implications of these results.

Los cerramientos verticales de Jean Prouvé variables de intercambio con el exterior

A finales del siglo XIX y principios del XX, la aparición de nuevos materiales, como el acero y el hormigón armado, y la experimentación en procedimientos industriales provocan un cambio en el concepto de cerramiento y en la forma de construir. La fachada se libera y se independiza de la estructura principal, y el nuevo cerramiento debe responder a los principios arquitectónicos y constructivos de este momento. Se busca, por tanto, un cerramiento nuevo. Un cerramiento ligero, de poco peso, de poco espesor, autoportante, multicapa, montado en seco, de grandes dimensiones y que cumpla las exigencias de todo cerramiento. Se puede afirmar que, hasta que Jean Prouvé experimenta con distintos materiales y sistemas de fabricación, la técnica de los cerramientos ligeros no se desarrolla por completo. En sus trabajos se pueden encontrar aplicaciones de los nuevos materiales y nuevas técnicas, e investigaciones sobre prefabricación ligera en acero y aluminio, en un intento de aplicar la producción industrial y en serie a la construcción. Esta Tesis realiza un análisis en profundidad, tanto gráfico como escrito, de los cerramientos verticales desarrollados por Jean Prouvé, sin tratarlos como objetos aislados, entendiendo que forman parte de una obra arquitectónica concreta y completa. Dicho análisis sirve para clasificarlos según las funciones esenciales que debe garantizar un cerramiento: aislar, iluminar, ventilar y proteger, y para comprender cuáles son las claves, los recursos e intenciones, utilizadas por el autor para conseguir este propósito. El resultado de la investigación se plasma de dos formas diferentes. En la primera, se realizan reflexiones críticas para extraer los temas importantes de los elementos analizados, lo que posibilita el acercamiento a otros arquitectos y ampliar el campo de visión. En la segunda, de tipo gráfico, se elabora un atlas de los distintos tipos de cerramientos verticales desarrollados por Jean Prouvé. ABSTRACT In the late nineteenth and the early twentieth century, the appearance of new materials, like steel or reinforced concrete, and the experimentation in industrial procedures cause a change in the concept of façade and in the way of build. The façade is released and become independent of the main structural frame, and the new building enclosure must answer the architectural and construction principles of that moment. A new façade is therefore looked for. A light, thin, self supported, multi layer, dry mounted and big dimensions façade that meet the exigencies of all building enclosure. You can ensure that until Jean Prouvé experiment with several materials and fabrication systems, the light façade technic does not develop completely. In his work we can find new materials applications and new technics and studies about light prefabrication with steel and aluminium, in an attempt of apply the mass production to construction. This Thesis carries out a deep analysis, graphic and written, of the vertical enclosure panels of Jean Prouvé’s work. This is made without studying them like isolated objects, but understanding that they are part of a particular architectural work, as a whole. The analysis is used for classify the panels according to main functions that a façade must satisfy: isolate, light up, ventilate and protect. And also to understand which are the keys, the resources and intentions used by Prouvé to achieve this goal. The result of the research is presented in two different ways. In the first one, a critical reflection is made in order to extract the important issues of the analyzed elements. That makes possible the approach to other architects and gives us a bigger range of vision. In the second, graphic, an atlas of the different types of vertical façade panels of Jean Prouvé is made.