Study of the surface hardness and modulus of elasticity of conventional and microwave-cured acrylic resins

The aim of this study was to evaluate the following acrylic resins: Clássico®, QC-20® and Lucitone®, recommended specifically for thermal polymerization, and Acron MC® and VIPI-WAVE®, made for polymerization by microwave energy. The resins were evaluated regarding their surface nanohardness and modulus of elasticity, while varying the polymerization time recommended by the manufacturer. They were also compared as to the presence of water absorbed by the samples. The technique used was nanoindentation, using the Nano Indenter XP®, MTS. According to an intra-group analysis, when using the polymerization time recommended by the manufacturer, a variation of 0.14 to 0.23 GPa for nanohardness and 2.61 to 3.73 GPa for modulus of elasticity was observed for the thermally polymerized resins. The variation for the resins made for polymerization by microwave energy was 0.15 to 0.22 GPa for nanohardness and 2.94 to 3.73 GPa for modulus of elasticity. The conclusion was that the Classico® resin presented higher nanohardness and higher modulus of elasticity values when compared to those of the same group, while Acron MC® presented the highest values for the same characteristics when compared to those of the same group. The water absorption evaluation showed that all the thermal polymerization resins, except for Lucitone®, presented significant nanohardness differences when submitted to dehydration or rehydration, while only Acron MC® presented no significant differences when submitted to a double polymerization time. Regarding the modulus of elasticity, it was observed that all the tested materials and products, except for Lucitone®, showed a significant increase in modulus of elasticity when submitted to a lack of hydration.

Effect of Low-Level Laser Therapy on Malondialdehyde Concentration in Random Cutaneous Flap Viability

Objective: The aim of this study was to assess the effects of 830 and 670 nm laser on malondialdehyde (MDA) concentration in random skin-flap survival. Background Data: Low-level laser therapy (LLLT) has been reported to be successful in stimulating the formation of new blood vessels and activating superoxide-dismutase delivery, thus helping the inhibition of free-radical action and consequently reducing necrosis. Materials and Methods: Thirty Wistar rats were used and divided into three groups, with 10 rats in each one. A random skin flap was raised on the dorsum of each animal. Group 1 was the control group; group 2 received 830 nm laser radiation; and group 3 was submitted to 670 nm laser radiation. The animals underwent laser therapy with 36 J/cm(2) energy density immediately after surgery and on the 4 days subsequent to surgery. The application site of the laser radiation was 1 point, 2.5 cm from the flap's cranial base. The percentage of the skin-flap necrosis area was calculated 7 days postoperative using the paper-template method, and a skin sample was collected immediately after as a way of determining the MDA concentration. Results: Statistically significant differences were found between the necrosis percentages, with higher values seen in group 1 compared with groups 2 and 3. Groups 2 and 3 did not present statistically significant differences (p > 0.05). Group 3 had a lower concentration of MDA values compared to the control group (p < 0.05). Conclusion: LLLT was effective in increasing the random skin-flap viability in rats, and the 670 nm laser was efficient in reducing the MDA concentration.

Generation and characterization of human insulin-releasing cell lines

Background: The in vitro culture of insulinomas provides an attractive tool to study cell proliferation and insulin synthesis and secretion. However, only a few human beta cell lines have been described, with long-term passage resulting in loss of insulin secretion. Therefore, we set out to establish and characterize human insulin-releasing cell lines. Results: We generated ex-vivo primary cultures from two independent human insulinomas and from a human nesidioblastosis, all of which were cultured up to passage number 20. All cell lines secreted human insulin and C-peptide. These cell lines expressed neuroendocrine and islets markers, confirming the expression profile found in the biopsies. Although all beta cell lineages survived an anchorage independent culture, none of them were able to invade an extracellular matrix substrate. Conclusion: We have established three human insulin-releasing cell lines which maintain antigenic characteristics and insulin secretion profiles of the original tumors. These cell lines represent valuable tools for the study of molecular events underlying beta cell function and dysfunction.

Undergraduate student experiences and perceptions of group projects

This paper reports the experiences and perceptions of student group projects of three cohorts of undergraduates: a 3rd year capstone course in professional communication (N = 54), a 3rd year elective in chemical engineering (N = 29), and a core 2nd-year course in chemical engineering (N = 74).

Triple objective team mentoring: achieving learning objectives with chemical engineering students

A sophisticated style of mentoring has been found to be essential to support engineering student teams undertaking technically demanding, real-world problems as part of a Project-Centred Curriculum (PCC) at The University of Queensland. The term ‘triple-objective’ mentoring was coined to define mentoring that addresses not only the student’s technical goal achievement but also their time and team management. This is achieved through a number of formal mentor meetings that are informed by a confidential instrument which requires students to individually reflect on team processes prior to the meeting, and a checklist of technical requirements against which the interim student team progress and achievements are assessed. Triple-objective mentoring requires significant time input and coordination by the academic but has been shown to ensure effective student team work and learning undiminished by team dysfunction. Student feedback shows they value the process and agree that the tools developed to support the process are effective in developing and assessing team work and skills with average scores mostly above 3 on a four point scale.

Reconceptualising social sustainability in urban development

Although the social dimension is often cited as the third leg of triple bottom line sustainability, there is at present general agreement on the difficulty of saying just what social sustainability is and how it can be related to enivironmental sustainability. This paper proposes that a sociotechnical understanding of the relationship beween human behaviour and technical developments provides a way of making the social dimension accessible to engineers, designers and developers. We draw on early work in master planned urban developments to show how a sociotechnical model, married to a life cycle assessment approach can help us understand and design for effective and efficient implementation of sustainability systems

Height and weight gains in a nutrition rehabilitation day-care service

Objective: To evaluate nutritional recovery patterns in 106 undernourished children assisted by the Center of Nutritional Recovery and Education (CREN, in Portuguese) between January 1995 and December 1999. Design: CREN assists undernourished children aged 0 to 72 months living in the southern regions of Sao Paulo, in an outpatient setting. Nutritional status was assessed by Z-scores of weight-for-age, height-for-age and weight-for-height. Nutritional recovery evaluation considered Z-score gains in weight-for-age and height-for-age, grouping into four categories (Z-score increment of 0.50 between groups). Children with birth weight less than 2500 g were classified as low birth weight (LBW), while those born at term and with LBW were classified as small for gestational age. Setting: CREN (Center of Nutritional Recovery and Education in Portuguese), Sao Paulo, Brazil. Subjects: One hundred and six children from CREN. Results: Among the 106 evaluated children, ninety-eight (92.5%)recovered their weight or height and seventy-two (67.9%) recovered both. Nearly half of studied children presented a nutritional recovery (increase in Z-score) of more than 0.50 in height-for-age (46.2%) and about 40% in weight-for-age (38.7%). Multivariate analysis showed that treatment duration and initial weight-for-age contributed to weight-for-age Z-score increment, explaining 25% of the variation; and treatment duration, initial height-for-age and weight-for-age Z-score increment contributed to height-for-age Z-score increment, explaining 62% of the variation. Conclusions: Our findings show that nutritional recovery among children who attended CREN was influenced primarily by the degree of nutritional deficit at admission. It has also been shown that biological variables are more important than socio-economic status in determining the rate of nutritional recovery.

Mutations involved in Aicardi-Goutieres syndrome implicate SAMHD1 as regulator of the innate immune response

Aicardi-Goutieres syndrome is a mendelian mimic of congenital infection and also shows overlap with systemic lupus erythematosus at both a clinical and biochemical level. The recent identification of mutations in TREX1 and genes encoding the RNASEH2 complex and studies of the function of TREX1 in DNA metabolism have defined a previously unknown mechanism for the initiation of autoimmunity by interferon-stimulatory nucleic acid. Here we describe mutations in SAMHD1 as the cause of AGS at the AGS5 locus and present data to show that SAMHD1 may act as a negative regulator of the cell-intrinsic antiviral response.

Tooth Tissue Engineering: Optimal Dental Stem Cell Harvest Based on Tooth Development

Our long-term objective is to devise reliable methods to generate biological replacement teeth exhibiting the physical properties and functions of naturally formed human teeth. Previously, we demonstrated the successful use of tissue engineering approaches to generate small, bioengineered tooth crowns from harvested pig and rat postnatal dental stem cells (DSCs). To facilitate characterizations of human DSCs, we have developed a novel radiographic staging system to accurately correlate human third molar tooth developmental stage with anticipated harvested DSC yield. Our results demonstrated that DSC yields were higher in less developed teeth (Stages 1 and 2), and lower in more developed teeth (Stages 3, 4, and 5). The greatest cell yields and colony-forming units (CFUs) capability was obtained from Stages 1 and 2 tooth dental pulp. We conclude that radiographic developmental staging can be used to accurately assess the utility of harvested human teeth for future dental tissue engineering applications.

Estudo do efeito aprendizagem em exames audiométricos sequenciais de trabalhadores de indústria metalúrgica e suas implicações nos programas de conservação auditiva

A avaliação audiométrica é crucial nos programas de prevenção das disacusias ocupacionais. Exames periódicos são comparados, um a um, com um exame admissional e a ocorrência de pioras desencadeia ações preventivas sobre o trabalhador e seu posto de trabalho. Muitos trabalhadores "melhoram" seus limiares, nos primeiros anos, devido ao efeito aprendizagem. Se tais melhoras forem contempladas pela legislação, a detecção das perdas auditivas poderá ser antecipada. OBJETIVO: Identificar o efeito aprendizagem nas audiometrias industriais e avaliar suas implicações, particularmente sobre a validade do exame audiométrico admissional. FORMA DE ESTUDO: Clínico retrospectivo. MATERIAL E MÉTODO: Foram analisados 835 audiogramas de 167 metalúrgicos e comparados cinco exames periódicos com o respectivo exame admissional. Foram consideradas como efeito aprendizagem as melhoras de 5 dB em freqüências isoladas ou em grupos de freqüências. RESULTADOS: De 92 a 96% dos trabalhadores apresentaram melhoras de 5 dB, entre 500 e 6.000 Hz, no período pesquisado. De 31 a 37% apresentaram melhoras de 5 dB, do segundo para o primeiro exame e de 23 a 35%, do quinto para o primeiro. Na média aritmética dos limiares em 500, 1.000 e 2.000 Hz e em 3.000, 4.000 e 6.000 Hz, de 16 a 23% apresentaram melhoras do segundo para o primeiro exame e de 11 a 15%, do quinto para o primeiro. CONCLUSÕES: O efeito aprendizagem produziu melhoras dos limiares tonais em mais de um terço da população estudada, nos seis primeiros exames audiométricos seqüenciais. Questiona-se, assim, a validade do primeiro exame audiométrico como referencial, para ser comparado com os seqüenciais.

Bois-bumbás de Parintins: síntese metafórica da realidade?

Este artigo analisa como os atores sociais internos percebem o evento dos bois-bumbás da cidade de Parintins, tendo em vista o valor que tal fenômeno representa para a comunidade local nos aspectos culturais, econômicos e sociais, e por criar um espaço onde os seus integrantes possam refletir, falar e produzir conhecimento sobre sua realidade. Procurou-se identificar a percepção dos atores sociais internos sobre a influência desse fenômeno cultural nas dimensões sistêmica e cultural do desenvolvimento local sustentável (DLS) da cidade de Parintins. Os pressupostos que orientaram o estudo foram: elementos da cultura brasileira estão presentes na cultura local representada pelo contexto dos bois-bumbás; a cultura indígena amazônica dá significado aos elementos que possibilitam a construção dos bois-bumbás; e o boi-bumbá está se transformando em mercadoria subsumida às necessidades do capital. O referencial de análise baseou-se principalmente nos conceitos de DLS, modo de produção capitalista e cultura. A metodologia utilizada foi de natureza qualitativa. As conclusões sinalizam para a confirmação dos pressupostos.

Gestão do conhecimento numa instituição pública de assistência técnica e extensão rural do Nordeste do Brasil

Um dos problemas mais graves enfrentados pelas organizações públicas é a perda de conhecimento em transferências, rotatividade e aposentadorias de pessoal, pois tem como consequência a perda de know-how e capital intelectual, já que muitas informações, conhecimentos importantes e detalhes dos processos de trabalho ainda estão guardados apenas na mente das pessoas. Portanto, o objetivo deste estudo é identificar, a partir da percepção dos gestores de uma instituição pública de assistência técnica e extensão rural, a gestão do conhecimento. Para isso, utilizou-se do modelo de Diagnóstico de Gestão do Conhecimento proposto por Bukowitz e Williams (2002). A instituição estudada é um órgão de educação não formal do Nordeste do Brasil que executa políticas públicas de assistência técnica e extensão rural que beneficiam agricultores familiares. Trata-se de um estudo de caso de campo com abordagem quantitativa e método descritivo. Os dados foram registrados em planilhas eletrônicas e foram utilizadas as instruções do modelo escolhido para apuração dos resultados. Os resultados sinalizam uma contradição: uma organização que dissemina saberes para agricultores familiares não possui internamente a gestão formal do conhecimento que produz. Além disso, a instituição pesquisada é criadora de conhecimento, porém esse não é considerado seu negócio principal, por isso não gera inovação constante.

Consumo de substâncias psicoativas entre estudantes de rede privada

Em uma amostra de 1.441 alunos, representativa de estudantes de primeiro e segundo graus da rede privada do Distrito Federal (Brasil), foi realizado, em 1988, pesquisa com o objetivo de determinar a prevalência de consumo de álcool, fumo e drogas. Como instrumento de coleta de dados utilizou-se questionário adotado pela OMS, modificado. As prevalências do uso de substâncias psicoativas na vida (incluindo desde a experimentação até o uso diário) mostraram taxas de 67,2% para o álcool, 28,7% para o fumo, 13,9% para os inalantes, 6,1% para a maconha e 1,8% para a cocaína. O consumo da maioria das drogas mostrou-se crescente com a idade. Em relação ao sexo, as drogas ilícitas foram mais freqüentemente utilizadas pelos homens.

Diagnóstico nutricional de crianças de zero a cinco anos atendidas pela rede municipal de saúde em área urbana da região sul do Brasil, 1988

Como um dos requisitos para a operacionalização do Sistema de Vigilância Alimentar e Nutricional (SISVAN) no município de Curitiba, PR, Brasil, foi realizado um levantamento epidemiológico retrospectivo com dados de 1988, que buscou através do exame antropométrico conhecer a prevalência e as formas de desnutrição calórico-protéico de crianças menores de cinco anos atendidas pela Rede Municipal de Saúde de Curitiba. Numa amostra de 4.213 crianças encontrou-se pela Classificação de Gòmez 28,1% de desnutridos, sendo que 3,6% destes situam-se no grau II e III. A Classificação de Seoane e Latham modificada por Batista Filho revelou que 19,7% das crianças apresentam alguma forma de desnutrição. O perfil antropométrico revelou maior concentração de crianças no primeiro decil a partir do sexto mês de vida, sendo esta mais acentuada no grupo etário de 12 a 24 meses para os índices: peso/idade e altura/idade.

Avaliação da criopreservação e posterior capacidade fecundante de sémen de touto da Raça Brava a partir da recolha post-mortem

Dissertação de Mestrado, Engenharia Zootécnica, 24 de Abril de 2015, Universidade dos Açores.