32 research outputs found

    Both “illness and temptation of the enemy”: melancholy, the medieval patient and the writings of King Duarte of Portugal (r. 1433–38)

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    Recent historians have rehabilitated King Duarte of Portugal, previously maligned and neglected, as an astute ruler and philosopher. There is still a tendency, however, to view Duarte as a depressive or a hypochondriac, due to his own description of his melancholy in his advice book, the Loyal Counselor. This paper reassesses Duarte's writings, drawing on key approaches in the history of medicine, such as narrative medicine and the history of the patient. It is important to take Duarte's views on his condition seriously, placing them in the medical and theological contexts of his time and avoiding modern retrospective diagnosis. Duarte's writings can be used to explore the impact of plague, doubt and death on the life of a well-educated and conscientious late-medieval ruler

    Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)

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    From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions

    El arte de crear escribiendo: la producción textual en niños de la primera etapa de educación básica

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    Estudio de tipo cualitativo que persigue conocer el proceso seguido por un grupo de niños de primero y segundo grado en la producción de textos narrativos: cuentos. Se recolectó información a través de documentos escritos, observación participante, entrevista no estructurada. El análisis se realizó paralelamente a la recolección de los datos, ello fue base para organizar la propuesta pedagógica en el marco de un ambiente proclive para el aprendizaje de la escritura como proceso para construir significados. Se encontraron dos grandes categorías: 1.- Conocimiento que poseen los niños acerca del cuento como género literario: resultados obtenidos al analizar el primer borrador creado por los niños. 2.- Características del proceso de producción de cuentos: aspectos considerados por los niños al momento de producir sus textos, las dificultades encontradas, las soluciones ofrecidas y los avances logrados. En conclusión, los niños lograron: (a) Conocer la estructura básica del género literario cuento: inicio, conflicto, desenlace y final. (b) Utilizar el borrador como un instrumento para la producción escrita. (c) Incorporar la revisión como subproceso indispensable del proceso de escritur

    Supramolecular motifs in dynamic covalent PEG-hemiaminal organogels

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    \u3cp\u3eDynamic covalent materials are stable materials that possess reversible behaviour triggered by stimuli such as light, redox conditions or temperature; whereas supramolecular crosslinks depend on the equilibrium constant and relative concentrations of crosslinks as a function of temperature. The combination of these two reversible chemistries can allow access to materials with unique properties. Here, we show that this combination of dynamic covalent and supramolecular chemistry can be used to prepare organogels comprising distinct networks. Two materials containing hemiaminal crosslink junctions were synthesized; one material is comprised of dynamic covalent junctions and the other contains hydrogen-bonding bis-hemiaminal moieties. Under specific network synthesis conditions, these materials exhibited self-healing behaviour. This work reports on both the molecular-level detail of hemiaminal crosslink junction formation as well as the macroscopic behaviour of hemiaminal dynamic covalent network (HDCN) elastomeric organogels. These materials have potential applications as elastomeric components in printable materials, cargo carriers and adhesives.\u3c/p\u3

    Recyclable, strong thermosets and organogels via paraformaldehyde condensation with diamines

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    Nitrogen-based thermoset polymers have many industrial applications (for example, in composites), but are difficult to recycle or rework. We report a simple one-pot, low-temperature polycondensation between paraformaldehyde and 4,4′-oxydianiline (ODA) that forms hemiaminal dynamic covalent networks (HDCNs), which can further cyclize at high temperatures, producing poly(hexahydrotriazine)s (PHTs). Both materials are strong thermosetting polymers, and the PHTs exhibited very high Young's moduli (up to ∼14.0 gigapascals and up to 20 gigapascals when reinforced with surface-treated carbon nanotubes), excellent solvent resistance, and resistance to environmental stress cracking. However, both HDCNs and PHTs could be digested at low pH (<2) to recover the bisaniline monomers. By simply using different diamine monomers, the HDCN- and PHT-forming reactions afford extremely versatile materials platforms. For example, when poly(ethylene glycol) (PEG) diamine monomers were used to form HDCNs, elastic organogels formed that exhibited self-healing properties

    Recyclable, strong thermosets and organogels via paraformaldehyde condensation with diamines

    No full text
    Nitrogen-based thermoset polymers have many industrial applications (for example, in composites), but are difficult to recycle or rework. We report a simple one-pot, low-temperature polycondensation between paraformaldehyde and 4,4′-oxydianiline (ODA) that forms hemiaminal dynamic covalent networks (HDCNs), which can further cyclize at high temperatures, producing poly(hexahydrotriazine)s (PHTs). Both materials are strong thermosetting polymers, and the PHTs exhibited very high Young's moduli (up to ∼14.0 gigapascals and up to 20 gigapascals when reinforced with surface-treated carbon nanotubes), excellent solvent resistance, and resistance to environmental stress cracking. However, both HDCNs and PHTs could be digested at low pH (&lt;2) to recover the bisaniline monomers. By simply using different diamine monomers, the HDCN- and PHT-forming reactions afford extremely versatile materials platforms. For example, when poly(ethylene glycol) (PEG) diamine monomers were used to form HDCNs, elastic organogels formed that exhibited self-healing properties.</p

    Recyclable, strong thermosets and organogels via paraformaldehyde condensation with diamines

    No full text
    \u3cp\u3eNitrogen-based thermoset polymers have many industrial applications (for example, in composites), but are difficult to recycle or rework. We report a simple one-pot, low-temperature polycondensation between paraformaldehyde and 4,4′-oxydianiline (ODA) that forms hemiaminal dynamic covalent networks (HDCNs), which can further cyclize at high temperatures, producing poly(hexahydrotriazine)s (PHTs). Both materials are strong thermosetting polymers, and the PHTs exhibited very high Young's moduli (up to ∼14.0 gigapascals and up to 20 gigapascals when reinforced with surface-treated carbon nanotubes), excellent solvent resistance, and resistance to environmental stress cracking. However, both HDCNs and PHTs could be digested at low pH (&lt;2) to recover the bisaniline monomers. By simply using different diamine monomers, the HDCN- and PHT-forming reactions afford extremely versatile materials platforms. For example, when poly(ethylene glycol) (PEG) diamine monomers were used to form HDCNs, elastic organogels formed that exhibited self-healing properties.\u3c/p\u3
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