The design of scaffolds to reach similar three-dimensional structures mimicking the natural and fibrous environment of some cells is a challenge for tissue engineering, and 3D-printing and electrospinning highlights from other techniques in the production of scaffolds. The former is a well-known additive manufacturing technique devoted to the production of custom-made structures with mechanical properties similar to tissues and bones found in the human body, but lacks the resolution to produce small and interconnected structures. The latter is a well-studied technique to produce materials possessing a fibrillar structure, having the advantage of producing materials with tuned composition compared with a 3D-print. Taking the advantage that commercial 3D-printers work with polylactide (PLA) based filaments, a biocompatible and biodegradable polymer, in this work we produce PLA-based composites by blending materials obtained by 3D-printing and electrospinning. Porous PLA fibers have been obtained by the electrospinning of recovered PLA from 3D-printer filaments, tuning the mechanical properties by blending PLA with small amounts of polyethylene glycol and hydroxyapatite. A composite has been obtained by blending two layers of 3D-printed pieces with a central mat of PLA fibers. The composite presented a reduced storage modulus as compared with a single 3D-print piece and possessing similar mechanical properties to bone tissues. Furthermore, the biocompatibility of the composites is assessed by a simulated body fluid assay and by culturing composites with 3T3 fibroblasts. We observed that all these composites induce the growing and attaching of fibroblast over the surface of a 3D-printed layer and in the fibrous layer, showing the potential of commercial 3D-printers and filaments to produce scaffolds to be used in bone tissue engineering.
O presente trabalho teve como finalidade ajustar modelos matemáticos para estimar o volume do fuste e ramos para a espécie Brachystegia gossweilerii Hutch. & Burt Davy. Para o efeito, foram derrubadas e rigorosamente cubadas 53 árvores da espécie acima mencionada. A área de estudo corresponde a floresta de Miombo da Aldeia Calombo, comuna do Cuima, Município da Caála, Província do Huambo. Os dados, obtidos das árvores foram processados, utilizando para o efeito o programa SPSS versão 15.0 para Windows. Os modelos de melhor ajuste para estimativa do volume do fuste com casca é o modelo aritmético de entrada simples logVrt = -1,058+1,023loggt+0,485*1/ log2gt, enquanto para os ramos foi o modelo Vrt = 0,297 * gt1,987.
La investigación se realizó con el objetivo de aplicar algunos modelos económico mate- máticos que faciliten el análisis de los indicadores de eficiencia en la producción de leche. Se propusieron, evaluaron y probaron diferentes variables económicas y productivas que caracterizan a las entidades productoras de leche. La metodología propuesta se basa en la interpretación del comportamiento de indicadores que se combinan a partir de variables de diferente naturaleza (económicas, técnicas, productivas) que sintetizan el uso de los factores de producción en sistemas ganaderos. Los modelos que se utilizan son el análisis envolvente de datos (AED) y el modelo estadístico de medición de impactos (MEMI). Este último basa- do en las técnicas del análisis multivariado y considerando que las aplicaciones en varia- bles económicas han sido escasas. Se incorporó en el trabajo un estudio de caso a través de una base de datos conformada por la información de seis Unidades Básicas de Producción Cooperativa (UBPC) en el período comprendido entre enero de 2008 y diciembre de 2010. Se pudo corroborar que las herramientas estadísticas utilizadas ayudan a perfeccionar los análisis en los diferentes niveles de organización de la producción (productores, inves- tigadores, profesores y decisores) que considera la interrelación existente en el sistema de variables, para formar índices que midan la eficiencia de la gestión. Se pudo comprobar el valor del AED y otras herramientas económico-matemáticas para definir los referentes productivos en las empresas ganaderas y su repercusión en el uso óptimo de los recursos de que dispone la ganadería en Cuba.
The objective of the study was to evaluate the main causes that affect the low productivity and quality of the primary link of the cattle production chain as an input for the food transformation industry and related to other destinations in the Ecuadorian Amazon region (RAE). Questionnaire were conducted with 399 variables from each of the Amazonian provinces to evaluate behavior in the productive, environmental, economic and social dimensions of livestock systems and animal behavior of the different breeds. The results were analyzed once the livestock systems were typified in each productive purpose, we analyzed the discrete variables that affect the behavior of the systems, related to the productive dimensions (individual milk production and birth rate) and ANAVA for breeding breeds more frequent in each of the provinces. The composition of the systems in the RAE showed that the most frequent breeds are Criollo (35.9) and mestizos without records (63.3%) with a specialized breed deficit that means that the agroindustrial sector is almost non-existent. The Norman races; Holstein and Brown Swiss present births of 82.47; 78.19 and 66.47% respectively, however they do not express their milk production potential due to the management system used. It is concluded that the link that presents the greatest vulnerability is the primary one (livestock farmers) mainly because in the RAE are producing with important productive deficiencies.
The milk industry seen from the farms of producers in the Ecuadorian Amazon.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.