VICARIA: An e-Learning System for Risk Assessment

An e-learning system in the risk assessment engineering domain has been developed by a consortium led by Ligeron® in the context of the Vicaria project (Leonado da Vinci – N° PP 118018). The e-learning platform: www.vicaria.fr has been implemented and hosted by OVH in compliance with SCORM (Shareable Content Object Reference Model) standard. The Vicaria modules contents have been defined according to an investigation performed in different European countries, particularly in France, to gather the user requirements. The Vicaria contents dedicated mainly to the environmental risks and ICPE are now available for use in French. The issue of the performed work and the e-learning system specifics are partly summarized in this pape

Impact properties analysis of rotationally molded polyethylene and polypropylene for a wide range of temperatures

Rotational molding is an established and growing manufacturing method for large, hollow plastic components. In this work the impact properties of rotationally molded Polyethylene (PE) and Polypropylene (PP) were tested at temperature in the range of -40 °C to 30 °C. Dynamic mechanical thermal analysis (DMTA) was performed to analyse the measured impact properties of PP and PE plastics. For PP, a very good relationship was found between peak impact strength and the loss modulus curve obtained in DMTA analysis. A relationship between density, β peak height and peak impact strength was found for PE which is different from previous findings in the literature. It is concluded that further work should focus on developing an understanding of the PE material's microstructure in order to more fully understand its impact properties

An investigation of low velocity impact properties of rotationally moulded skin-foam-skin sandwich structure

In this study, the low velocity impact properties of rotationally moulded skin-foam-skin sandwich structures were investigated experimentally since there is a need for a greater understanding of the impact behaviour of these composites in service to extend the range of their applications. Polyethylene rotationally moulded sandwich structures were manufactured at various skin and core layer thickness combinations and tested using an instrumented low velocity drop weight impact testing machine at 20J to 100J impact energy levels, at room temperature. This allowed the identification of the impact response, failure mode, the effects of the skin and core layer thickness on impact resistance. Force-deflection curves, maximum force, contact time, maximum deflection versus impact energy curves were analysed. Samples were seen to fail due to the indentation dart piercing the upper and lower skins, with crushing and consolidation seen in the core foamed layer. Delamination at the core/skin interface was not observed. It was found that fracture initiates from the lower skin and then continues to grow to the upper skin via the foamed core layer. The impact resistance was noted to increase with increasing skin and core layer thickness, though an increase in skin layer thickness had a greater contribution than an increase in the core layer thickness. Keywords: Rotational moulding, skin-foam-skin, sandwich, low velocity impact, PE

Preliminary evaluation of tooth coloration potential and wear of full-contour alumina in vitro

PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact [email protected] (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2013 (Department of Restorative Sciences and Biomaterials).Includes bibliography: leaves 54-64.Objective: The objective of this study was: a. to evaluate the effect of color-infusion of alumina at pre-sintered porous stage with different metal salt solutions, at different concentrations; resulting in a variety of shades corresponding to VITA Classical and VITA 3D Master shade guides; b. to assess the wear behavior of alumina against VITA Mark II (VMKII). Methods: Color: thirty four alumina tiles (19x15x3mm) were sliced and made off of In-Ceram 2000 AL-20 blocks (Vident VITA) to be infused with coloring solutions. Six different elements were chosen to form our coloring solutions: rare earths Ce, Er, Nd, and Pr along with Zn in the form of acetate at two different concentrations of 1% and 5% (by weight); and Sn solution in the form of oxide at 15% concentration. Thus, we had eleven solution groups (n=3) and one alumina tile was not color-infused as the control. Color measurement was done with a clinical spectrophotometer (Easyshade Compact, Vident VITA) for shades and CIEL*a*b* parameters. Three measurements were made for each specimen. [Delta]E values relative to the control were compared for 1% and 5% concentrations of each solution. Unpaired student t-test was used for statistical analysis, [alpha]=0.95. Wear: Feldspathic porcelain VITA Mark II pins (Vident VITA) were trephined out of ceramic blocks and cemented on one end of brass rods. Alumina tiles were mounted onto metal plates to form tracks for the pins to slide against them in the wear simulator for 200,000 cycles and at baseline, 1K, 10K, 50K, 100K, 150K, and 200K data-gathering points the following parameters were measured: length (Mark II), weight, surface roughness (alumina), and groove depth (alumina only at baseline and 200K). Results: Mean [Delta]E values were as follows: Ce: 1%: 17.01[plus or minus]0.08, 5%: 24.57[plus or minus]0.15; Er: 1%: 6.29[plus or minus]0.23, 5%: 8.28[plus or minus]0.21; Nd: 1%: 10.54[plus or minus]0.10, 5%: 20.23[plus or minus]0.34; Zn: 1%: 10.05[plus or minus]0.61, 5%: 11.31[plus or minus]0.38; Pr: 1%: 7.71[plus or minus]0.52, 5%: 13.14[plus or minus]0.56; Sn 15%: 8.37[plus or minus]0.39. There were significant differences between [Delta]E values for 1% and 5% concentrations (P[less than]0.05). Mean length loss and weight loss for Mark II specimens almost followed the same continuous trend until around 150K cycles when the trend started to show a marked decrease. Surface roughness values decreased throughout the experiment for alumina until it plateaued at 150K cycles, indicating a highly polished surface (0.023[plus or minus]0.005 Ra, [mu]m). Weight loss values for alumina specimens were marked as zero because they were not detectable by the weight measurement device used in this study. Conclusion: All coloring solutions changed the color of alumina specimens relative to the control into shades corresponding to VITA Classical and 3D Master shades and the results were concentration-dependent; alumina specimens remained almost intact throughout the wear experiment in terms of weight and groove depth, While Mark II specimens exhibited weight and vertical length loss; unpolished alumina caused a higher wear rate of VITA Mark II specimens; but decrease in surface roughness of alumina specimens resulted in decrease in their abrasiveness

Pseudoplastic deformation pits on polished ceramics due to cavitation erosion

In a previous study, pseudoplastic deformation pits created by cavitation exposure were reported in silicon nitride and zirconia. In this research, further comparison of the size and number of pits between several silicon nitride and zirconia materials is carried out. The pits are larger and much more numerous in silicon nitride than in zirconia although silicon nitride is harder than zirconia. An explanation of this phenomenon is given. Also, in the previous study it was reported that apparently a partially stabilized zirconia with yttria oxide developed a delay in the phase transformation from tetragonal to monoclinic after being exposed to cavitation. In this research, further experiments related with this phase transformation delay are carried out. Also, the phase transformation is verified with X-ray diffraction analysis. It is concluded that the “activation” of the partial stabilized zirconia happens regardless of the oxide used to stabilize it

Estimation of the workload added on the health system due to unwanted pregnancies and Children born of these pregnancies in kohgiloyeh Boyrahmad province 2010-2011

Background & aim: Unwanted pregnancy increases maternal and child mortality and increases health centers workload. The purpose of this study was to estimate the additional workload caused by unwanted pregnancies in the province's health system of Kohgilouyeh & Boyerahmad province, Iran. Methods: The present cross-sectional study was conducted in the second half of 2009 on the prenatal care for pregnant women referred to city health centers. Frequency of maternal and child care were assessed according to the latest Ministry of Health guidelines. Average time required to provide each patient was calculated based on the role results, then added workload was assessed. Data were analyzed using SPSS software. Results: An overall 350 unwanted pregnancy cases were identified. Assuming the same unwanted pregnancies in the first half and the second year of 2009 total of 21,140 times the equivalent of 3696 hours of extra work visit were added to the labor working primary health care centers in the city. Conclusion: Unwanted pregnancies resulting in increased staff workload of health centers, and if not provided with sufficient manpower, it may lead to the reduction of maternal and child health care qualities of these centers