993 resultados para Corrosion protection


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This article argues for the adoption of an evidence-based approach to decision-making in child protection. Such a change hinges upon the availability of good quality, up-to-date evidence that is readily accessible to practitioners and policy-makers. Following a resume' of the arguments for recognizing controlled trials as methodologically superior to other forms of methodology in evaluating professional interventions, the article presents the case for adopting a similarly rigorous approach to synthesizing research findings. It then identifies a range of obstacles to promoting evidence-based practice and makes recommendations for changes in training, research, and practice which might facilitate improvement in both primary research and in reviews of the literature.

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The chemical and mechanical stability of slag activated with two different concentrations of sodium sulfate (Na2SO4) after exposure to elevated temperatures ranging from 200 to 800 °C with an increment of 200 °C has been examined. Compressive strengths and pH of the hardened pastes before and after the exposure were determined. The various decomposition phases formed were identified using X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. The results indicated that Na2SO4 activated slag has a better resistance to the degradation caused by exposure to elevated temperature up to 600 °C than Portland cement system as its relative strengths are superior. The finer slag and higher Na2SOconcentration gave better temperature resistance. Whilst the pH of the hardened pastes decreased with an increase in temperature, it still maintained a sufficiently high pH for the protection of reinforcing bar against corrosion.

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International evidence confirms that early childhood educators can enter professional practice unprepared for child protection due to inadequate pre-service preparation. This paper makes an original contribution by using the Child Protection Questionnaire for Educators (CPQE) to examine the pre- and post- intervention child maltreatment and protection knowledge of early childhood and primary teaching students. While students’ knowledge increases significantly after participating in a child protection training programme, Pastoral Pathways, as part of their undergraduate study, post-intervention scores vary between groups. The study provides evidence of programme effectiveness and future training needs of pre-service educators. Findings are relevant to teacher educators and child care training providers in relation to programme content development and evidencing knowledge and skills acquisition.

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This study was conducted to determine the perivascular cell responses to increased endothelial cell expression of insulin-like growth factor binding protein-3 (IGFBP-3) in mouse retina. The contribution of bone marrow cells in the IGFBP-3-mediated response was examined using green fluorescent protein-positive (GFP(+)) adult chimeric mice subjected to laser-induced retinal vessel occlusion injury. Intravitreal injection of an endothelial-specific IGFBP-3-expressing plasmid resulted in increased differentiation of GF(P)+ hematopoietic stem cells (HSCs) into pericytes and astrocytes as determined by immunohistochemical analysis. Administration of IGFBP-3 plasmid to mouse pups that underwent the oxygen-induced retinopathy model resulted in increased pericyte ensheathment and reduced pericyte apoptosis in the developing retina. Increased IGFBP-3 expression reduced the number of activated microglial cells and decreased apoptosis of neuronal cells in the oxygen-induced retinopathy model. In summary, IGFBP-3 increased differentiation of GFP(+) HSCs into pericytes and astrocytes while increasing vascular ensheathment of pericytes and decreasing apoptosis of pericytes and retinal neurons. All of these cytoprotective effects exhibited by IGFBP-3 overexpression can result in a more stable retinal vascular bed. Thus, endothelial expression of IGFBP-3 may represent a physiologic response to injury and may represent a therapeutic strategy for the treatment of ischemic vascular eye diseases, such as diabetic retinopathy and retinopathy of prematurity. (Am J Pathol 2011, 178:1517-1524; DOI: 10.1016/j.ajpath.2010.12.031)