Natural Rubber Latex Biomaterials in Bone Regenerative Medicine

Natural rubber latex (NRL) is a white and milky solution that exudes from Hevea brasiliensis bark when perforated, and it has been appointed as a new promising biomaterial. NRL has been proven to be a very biocompatible material, and several new biomedical applications have been proposed. NRL has been proven to stimulate angiogenesis, cellular adhesion and formation of extracellular matrix, besides promoting replacement and regeneration of tissue. NRL also can be used as an occlusive membrane for guided bone regeneration (GBR) with promising results. Therefore, the aim of this chapter is to review NRL studies and to present NRL membrane as a promising biomembrane for use in bone trauma and injury

IN VITRO ASSESSMENT OF CYTOTOXICITY AND OXIDATIVE STRESS PARAMETERS OF NATURAL RUBBER LATEX MEMBRANES STABILIZED WITH DIFFERENT CONCENTRATIONS OF AMMONIA IN CHO-K1 CELLS

The purpose of this study was to assess in vitro cytotoxicity of natural rubber (NR) latex membranes stabilized with different concentrations of ammonia, as well as evaluate possible changes in oxidative stress parameters. To this end, CHO-k1 cells were exposed to NR membranes for 24 h. Cytotoxicity was assessed by the MTT assay and the oxidative stress parameters were established by glutathione (GSH) and malondialdehyde (MDA) levels. The results show that the ammonia present in the NR latex membranes can deplete cell viability and enhance GSH consumption in the cells. NR latex membranes stabilized with 2.00% of ammonia were cytotoxic to the cell lineage used in this study. From these results, it is possible to infer that the use of ammonia to stabilize NR latex membranes with biomedical purposes has to be done carefully, to avoid possible harmful effects to human health

A investigação enquanto prática de deliberação curricular: o caso do projecto ICR

Este artigo refere-se a um projecto de investigação curricular colaborativa que nasceu da conjugação entre, por um lado, a preocupação de alguns professores do ensino básico com o desinteresse manifestado por determinados alunos em relação à escola e ao currículo e, por outro, o interesse de alguns professores universitários em estudar questões de relevância curricular. Dessa conjugação resultou a assunção de uma dimensão investigativa na prática profissional dos referidos professores do ensino básico, concretizada num projecto de investigação-acção colaborativa conduzido por uma equipa de quatro docentes universitários e dez docentes do ensino básico (todos os ciclos), que têm estudado a problemática do reconhecimento (ou não), por parte dos alunos, da relevância das aprendizagens escolares. A recolha de dados tem sido feita em sucessivos ciclos de investigação-acção, com a duração de um ano escolar cada, principalmente através do registo sistemático de manifestações de desinteresse (por parte dos alunos em relação ao currículo) observadas nas aulas e de entrevistas aos alunos, conduzidas pelos seus professores. Os dados têm sido analisados pelos próprios professores do ensino básico, com o apoio dos docentes universitários, e sujeitos a interpretações individuais e de equipa, sendo essas interpretações inspiradoras de novas estratégias de ensino, que são continuamente monitorizadas e revistas. Os processos já amadurecidos e os resultados já gerados sugerem que, apesar da existência de algumas dificuldades, é possível desenvolver nas escolas do ensino básico práticas de gestão curricular que integrem uma componente de investigação.ABSTRACT: This article describes a project of collaborative research on curriculum, which was created by a team that includes (1) elementary school teachers worried about the lack of interest shown by some of their students with regard to the school and the curriculum, and (2) university professors interested in studying issues of curriculum relevance. This partnership has contributed to an increased use of research in classrooms by those elementary school teachers, through an action research project focused on students’ acknowledgment of the relevance of what they learn in school. Data has been collected in successive cycles of action research, mainly through classroom field notes that provide evidence of given students’ lack of interest with regard to the curriculum, and through interviews conducted by the teachers. Each action research cycle is one school year long. Data have been analyzed by the elementary school teachers, sometimes with support from the university professors, and interpreted both individually and collectively. Such interpretation of data inspires teachers in designing new teaching strategies, which are continuously monitored and reviewed. The processes that have already been consolidated and the results that have already been generated by this project suggest that, despite some difficulties, it is possible to develop curricula in elementary schools in ways that entail research

Sustainable blends of LDPE/NR and sugarcane bagasse ashes with PE-g-MA thermomechanical relationships

The polymer blends obtained with residues that before were called wastes has been growing as a viablesolution, allowing improvements in the mechanical properties and as sustainable alternative. This workreports the effects of blends of low-density polyethylene (LDPE) and natural rubber (NR), with sugarcane bagasse ash (SCBA) as filler, with and without polyethylene-graft-maleic anhydride (PE-g-MA)how coupling agent. The dynamic mechanical behavior and a stress-strain analysis were studied. Thematerials were further evaluated by differential scanning calorimetry and morphological observations.The results showed that incorporation of the PE-g-MA reduced the strain and improved the stress and theYoung module of the mixtures. Moreover, the presence of SCBA increased the hardness whilemaintaining the tensile strength and the elongation behavior of the polymer. The results demonstrate thepotential use of SCBA in the elastomer and thermoplastic mixture, free of vulcanization agents.Keywords: Sustainable blends, sugarcane bagasse ashes, natural rubber, low density polyethylene,polyethylene-graft-maleic anhydride