Bone was a crucial biological material for the evolution of large terrestrial organisms and is today essential for most of our daily activities and well-being. From an engineering perspective, this living material features highly desirable properties for modern load-bearing structures. It is made of abundant and environmental-friendly building blocks, which are combined into a tough and durable structure that can continuously modify itself to adapt to changes in the mechanical load imposed by the surroundings. In this review article, we compile and discuss scientific findings that allow us to understand bone as a complex system with properties that emerge from cell-mediated interactions of molecules and particles at multiple length scales. Analogous to other complex systems, such interactions lead to self-organization, hierarchical structures and adaptive behavior without the need of a central controlling unit. A rich range of physical, chemical and biological phenomena provide a framework for information to be generated and processed in this complex system. Understanding the interplay between such underlying phenomena and their emerging properties should help the diagnosis and treatment of bone-related medical conditions and might provide guidelines for the future development of more sustainable materials and engineering structures.
Abstract Plant oils and their derivatives have been vigorously exploited as alternatives for synthesis of epoxides due to depletion of petroleum resources. In this study, crude jatropha oil (CJO) was subjected to a transesterification process to form jatropha methyl esters (JME) using peroxyacetic acid generated in situ from hydrogen peroxide and acetic acid via an acidic ion exchange resin (AIER). The effect of temperature, molar ratio of hydrogen peroxide to unsaturation, molar ratio of acetic acid to unsaturation, and catalyst loading were investigated. This study revealed that the maximum 89.9% relative conversion to oxirane rings was achieved after 6 h with the optimal reaction conditions of temperature at 70 ˚C, the molar ratio of hydrogen peroxide to unsaturation of 1.5 mol, the molar ratio of acetic acid to unsaturation of 0.5 mol, and catalyst loading of 16%. Fourier Transform Infrared (FTIR) spectra of the epoxidized jatropha methyl esters (EJME) showed oxirane peaks (doublet) at 825 and 843 cm-1.1H NMR confirmed the diepoxide group at 2.85 ppm and 2.98 ppm, while the diepoxide signals of 1C NMR were present at 56.88-57.06 ppm. Production of bio-epoxides from Jatropha methyl esters hence looks promising with favorable physicochemical properties, availability, and versatility.
The construction of dams can increase the emission of greenhouse gases (GHG), mainly methane (CH4) by the anaerobic decomposition of forest residues like twigs, branches, leaves and miscellaneous flooded. The aim of this study was to evaluate the emission of CH4 after the flooding of soil covered with residuals of forests. Experimental units were built with PVC tubes containing soil covered with different combinations of dose (0; 21.2; 42.3 and 64.1 Mg ha-1) and type (branches, leaves and miscellaneous; twigs; and original composition) of forest residues and river water. The experimental design was completely randomized with factorial arrangement and three replications. Rates of CH4 emission were monitored in 19 events during one year (February/2012 to March/2013). Approximately, 75 days after incubation of soil with residue, a significant increase in CH4 emission was observed occurring two emission peaks: at 111 and 249 days. The cumulative emission of CH4 in the first year after flooding was 200 g C m-2 in the dose zero, until above 400 g C m-2 in the 21.2 Mg ha-1 and higher doses, with no effect of type of residues, only the dose as an isolated factor.
A construção de represas pode aumentar a emissão de gases do efeito estufa (GEE), principalmente metano (CH4) pela decomposição anaeróbica dos resíduos florestais, como galhos, ramos, folhas e miscelânea inundados. Objetivou-se, neste estudo, avaliar a emissão de CH4 após a inundação do solo coberto com resíduos florestais. Unidades experimentais foram construídas com tubos de PVC contendo solo e diferentes combinações de dose (0; 21,2; 42,3 e 64,1 Mg ha-1) e tipo de resíduos (folhas, ramos e miscelânea, galhos e composição original) e água de rio. O delineamento experimental foi inteiramente casualizado com arranjo fatorial e três repetições. As taxas de emissão de CH4 foram monitoradas em 19 eventos durante um ano (Fevereiro/2012 a Março/2013). Cerca de 75 dias após a incubação do solo com resíduos florestais verificou-se aumento das emissões de CH4, ocorrendo dois picos de emissão, aos 111 e aos 249 dias. A emissão acumulada de CH4 no primeiro ano de alagamento foi de 200 g C m-2 na dose zero, passando a valores próximos a 400 g C m-2 nas doses de 21,2 Mg ha-1 e maiores, não havendo efeito do tipo de resíduo, apenas da dose, como fator isolado.