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Tissue engineered bone scaffolds are potential alternatives to bone allografts and autografts. Porous scaffolds based on triply periodic minimal surfaces (TPMS) are good candidates for tissue growth because they offer high surface-to-volume ratio, have tailorable stiffness, and can be easily fabricated by additive manufacturing. However, the range of TPMS scaffold types is extensive, and it is not yet clear which type provides the fastest cell or tissue growth while being sufficiently stiff to act as a bone graft. Nor is there currently an established methodology for TPMS bone scaffold design which can be quickly adopted by medical designers or biologists designing implants. In this study, we examine six TPMS scaffold types for use as tissue growth scaffolds and propose a general methodology to optimise their geometry. At the macro-scale, the optimisation routine ensures a scaffold stiffness within suitable limits for bone, while at the micro-scale it maximises the cell growth rate. The optimisation procedure also ensures the scaffold pores are of sufficient diameter to allow oxygen and nutrient delivery via capillaries. Of the examined TPMS structures, the Lidinoid and Split P cell types provide the greatest cell growth rates and are therefore the best candidates for bone scaffolds. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) lacquer is a complex synthetic polymer. The mechanical properties of PU lacquers are influenced by the in-service environment, which may affect their function as protective coatings. As of date, limited research work has been published on the mechanical properties of PU lacquer films under environmental ageing conditions. This paper presents an investigation of the mechanical and hygroscopic behaviour of a commercial PU lacquer film. By means of water absorption and desorption tests, the diffusion coefficient and coefficient of hygroscopic expansion were determined. Tensile tests at constant displacement rates and creep tests under various UV/humidity ageing conditions showed a complex dependence of material properties on environmental conditions. A modified Burgers model with environment-dependent parameters is shown to satisfactorily model the mechanical behaviour of the PU lacquer in typical service conditions. [ABSTRACT FROM AUTHOR]

An experiment to measure granular temperature in a sheared low density granular bed containing a range of sizes of particles has been performed. Using positron emission particle tracking, a single particle was tracked from different size phases. From the coordinate data, the second moment of the velocity fluctuations about the mean flow in each direction was determined. It was found that the larger particles are 'hotter' and that most of the energy is contained in the θ (shearing) direction fluctuations. Evidence was found for Knudsen layer and higher order Burnett effects, suggesting extensions of the Navier-Stokes approaches are necessary to describe heat transport in polydisperse systems. [ABSTRACT FROM AUTHOR]

Background:There are limited data concerning the relationships between changes in adipocytokines and cardiovascular disease (CVD) risk factors.Objective:To examine the longitudinal associations between leptin, adiponectin, resistin and ghrelin levels and CVD risk factor levels in women at midlife.Design:Prospective, observational study.Subjects and measurements:Leptin, adiponectin, resistin, ghrelin levels and CVD risk factors were measured in specimens collected from 40 women at 3 points in time corresponding to the pre-, peri- and postmenopause stages of their natural menopause transition.Results:In longitudinal analyses adjusted for CVD risk factors and leptin at the previous menopausal stage, aging, education, smoking and physical activity, greater increases in leptin over the menopause transition were associated with greater decreases in high-density lipoprotein cholesterol (HDL-c) and greater increases in diastolic blood pressure, glucose, insulin and insulin resistance (all P<0.05). Larger decreases in adiponectin over the menopause transition were associated with greater increases in systolic blood pressure, insulin and insulin resistance and with greater decreases in HDL-c. Greater increases in ghrelin levels over the menopausal transition were associated with greater low-density lipoprotein cholesterol increases (P=0.014). Resistin was not associated with CVD risk factor changes.Conclusion:There were significant adverse associations of adipocytokines and ghrelin with multiple CVD risk factor changes in women across midlife. Given that this time period is dynamic for CVD risk, these data underscore the need for additional prospective studies.International Journal of Obesity (2008) 32, 740–748; doi:10.1038/sj.ijo.0803782; published online 8 January 2008 [ABSTRACT FROM AUTHOR]