On shrinkage and structure changes of pure and blended Portland concretes

This research investigates the long‐term shrinkage and Relative Mass Loss (RML) of mature Portland concretes (pure CEMI and blended CEMV/A), at temperatures of 20°C and 80°C. When placed at 80°C and at relative humidities (RH) below 50‐60%, concrete shrinkage increases with very slow stabilization kinetics by several hundreds of μm/m, while RML remains of about 0.2%. The origins of this continued shrinkage, simultaneously with limited RML, are investigated through the changes in (i) the pore structure of the concretes (by Mercury Intrusion Porosimetry and nitrogen adsorption) and in (ii) their solid phases (by TGA/DTA, FTIR spectroscopy coupled to DVS, quantitative X‐Ray Diffraction by Rietveld analysis, and ²⁹Si and ²⁷Al MAS NMR). While the pore structure coarsens during continued shrinkage, several phase transformations occur, namely ettringite decomposition and changes in the silicate chain length of the C–A–S–H. While these structural changes are documented, their relationship with shrinkage/RML and to the pore structure is novel.     

X-Ray Opaque Methacrylate Polymers for Biomedical Applications

The synthesis of a number of halogenated aromatic methacrylate monomers was achieved by (1) the esterification of hydroxyl-containing methacrylate esters with 2,3,5-tri-iodobenzoic acid and (2) by the nucleophilic addition of 2,3,5-tri-iodobenzoic acid, or polyhalogenated phenols, to 2,3-epoxypropyl methacrylate, yielding white crystalline products which were fully characterized. These monomers could be homopolymerized in the melt to produce clear, intensely X-ray opaque glasses possessing high refractive indices. The monomers themselves were soluble in a variety of methacrylate monomers with which they could be copolymerized to produce clear radiopaque materials. The stability of the homopolymers in an aqueous environment was excellent as was thermal stability, exhibiting little decomposition below 300°C. © 1997 SCI.     

Experiencing standardized media fragment annotations within HTML5

W3C’s Video in the Web activity aims at a better integration of media within the Web. In this paper, we show how two specifications currently under development within this activity, i.e., Media Fragment URIs and Media Annotations, can be combined within media-enabled HTML5 Web applications. In particular, we introduce a number of extensions for the Media Annotations ontology in order to close the gap with Media Fragment URIs. Additionally, we show how rich media fragment annotations can be converted into a WebVTT file. The latter can be used by HTML5-enabled players to show the annotations in a synchronized way. Further, a fully integrated Web application has been developed that shows how both specifications can work together within an HTML5 environment. This application relies on NinSuna, our media delivery platform targeted at multichannel publication that provides server-side support for both Media Fragment URIs and Media Annotations.     

High-temperature vibrational Raman spectroscopy of gaseous species for solid-oxide fuel cell research

This work reports the development of a novel high temperature, optically-accessed experimental facility and optical methods for Solid Oxide Fuel Cell (SOFC) research at the University of British Columbia (UBC). Vibrational Raman spectroscopy is applied to determine the flow-wise distributions of key gaseous species in a model Direct Internal Reforming (DIR) SOFC reformer fuelled with methane at operating temperatures of 600 and 700 °C. This work describes key aspects of the rig design for high temperature operation and details the in-situ calibration methodology developed to allow results to be reported in terms of mole fraction. A sample set of experimental results is presented and discussed. Elements of the reformer design and the operating characteristics of the apparatus that directly influence the results are identified. Potential applications of the apparatus are described.     

Prevalence and characteristics of overweight and obesity in indigenous Australian children: A systematic review

Evidence-based profiling of obesity and overweight in Indigenous Australian children has been poor. This study systematically reviewed evidence of the prevalence and patterns of obesity/overweight, with respect to gender, age, remoteness, and birth weight, in Indigenous Australian children, 0–18 years (PROSPERO CRD42014007626). Study quality and risk of bias were assessed. Twenty-five publications (21 studies) met inclusion criteria, with large variations in prevalence for obesity or overweight (11 to 54%) reported. A high degree of heterogeneity in study design was observed, few studies (6/21) were representative of the target population, and few appropriately recruited Indigenous children (8/21). Variability in study design, conduct, and small sample sizes mean that it is not possible to derive a single estimate for prevalence although two high-quality studies indicate at least one in four Indigenous Australian children are overweight or obese. Four of six studies reporting on gender, found overweight/obesity higher in girls and eight studies reporting on overweight/obesity by age suggest prevalence increases with age with one high quality large national study reporting total overweight/obesity as 22.4% of children aged 2–4 years, 27.5% of those aged 5–9, 38.5% aged 10–14, and 36.3% aged 15–17. Three of four studies, reporting obesity/overweight by region, found lower rates for children living in more remote areas than urban areas.     

Disposable microscope objective lenses for fluorescence correlation spectroscopy using latex microspheres

We explore the combination of a latex microsphere with a low NA lens to form a high performance optical system, and enable the detection of single molecules by fluorescence correlation spectroscopy (FCS). Viable FCS experiments at concentrations 1-1000 nM with different objectives costing less than $40 are demonstrated. This offers a simple and low-cost alternative to the conventional complex microscope objectives.     

Nd:YAG激光焊接中装夹预紧力对焊缝的影响

由于在焊缝处热影响区会产生较小的力的作用,预夹持力的大小在焊接过程中会不断变化.热膨胀、冷却过程中的收缩以及工件宽度的微小减少都会通过焊点影响夹持力的变化.试样的拉伸试验结果表明,加裁在试样上的夹持力一般会提高焊缝的断裂力,更重要的是可以得到优化后的焊接夹持力.