A epidemiologia da cardiomiopatia de Takotsubo no Brasil e os principais fatores de risco da cardiomiopatia de Takotsubo: The epidemiology of Takotsubo cardiomyopathy in Brazil and the main risk factors for takotsubo cardiomyopathy

A Cardiomiopatia de Takotsubo (CTT) é uma disfunção cardíaca reversível, a qual está relacionada, diretamente, ao estresse físico ou emocional. Objetiva-se através dessa pesquisa evidenciar os principais fatores de risco da CT. Trata-se de uma revisão sistemática realizada no motor de busca Biblioteca Virtual em Saúde (BVS) na base de dados das “Ciências em Saúde em Geral” (Scielo, Medline, Lilacs). Percebeu-se que que a CT apresenta uma ocorrência maior em mulheres na fase de pós-menopausa, onde são atingidas pelo estresse emocional, bem como a inserção de marcapasso também pode desencadear a doença. Entretanto, a etiologia da CT ainda é marcada por controvérsias, mas há concordância acerca do surgimento da CT estar relacionado com a abundância de catecolaminas circulantes

Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4′-diphenylmethane diisocyanate (MDI) was investigated. 31P NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers

Blends of ground tire rubber devulcanized by microwaves/HDPE - Part B: influence of clay addition

AbstractThe main objective of this work is to study the influence of clay addition on dynamically revulcanized blends of Ground Tire Rubber (GTR)/High Density Polyethylene (HDPE). GTR was previously devulcanized in a system comprised of a conventional microwave oven adapted with a motorized stirring, with a fixed microwave power and at various exposure times. The influence of clay addition on the final properties of the blends was evaluated in terms of mechanical, viscoelastic, thermal and rheological properties, with morphology being also analyzed. The results depict that the clay can modify the rheological behavior of the GTR phase, in addition to the thermal and mechanical properties of some blends

Blends of ground tire rubber devulcanized by microwaves/HDPE - Part A: influence of devulcanization process

<title>Abstract</title><p>The main objective of this work is the study of the influence of microwaves devulcanization of the elastomeric phase on dynamically revulcanized blends based on Ground Tire Rubber (GTR)/High Density Polyethylene (HDPE). The devulcanization of the GTR was performed in a system comprised of a conventional microwave oven adapted with a motorized stirring at a constant microwaves power and at various exposure times. The influence of the devulcanization process on the final properties of the blends was evaluated in terms of mechanical, viscoelastic, thermal and rheological properties. The morphology was also studied.</p

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved