Surfactant-laden liquid plug propagation and rupture occurring in lower lung airways are studied computationally using a front-tracking method. The plug is driven by an applied constant pressure in a rigid axisymmetric tube whose inner surface is coated by a thin liquid film. The evolution equations of the interfacial and bulk surfactant concentrations coupled with the incompressible Navier–Stokes equations are solved in the front-tracking framework. The numerical method is first validated for a surfactant-free case and the results are found to be in good agreement with the earlier simulations of Fujioka et al. (Phys. Fluids, vol. 20, 2008, 062104) and Hassan et al. (Intl J. Numer. Meth. Fluids, vol. 67, 2011, pp. 1373–1392). Then extensive simulations are performed to investigate the effects of surfactant on the mechanical stresses that could be injurious to epithelial cells, such as pressure and shear stress. It is found that the liquid plug ruptures violently to induce large pressure and shear stress on airway walls and even a tiny amount of surfactant significantly reduces the pressure and shear stress and thus improves cell survivability. However, addition of surfactant also delays the plug rupture and thus airway reopening.

The transport of relativistic electron beam in compressed cylindrical targets was studied from a numerical and experimental point of view. In the experiment, cylindrical targets were imploded using the Gekko XII laser facility of the Institute of Laser Engineering. Then the fast electron beam was created by shooting the LFEX laser beam. The penetration of fast electrons was studied by observing Kα emission from tracer layers in the target.

Recent studies suggest that sand can serve as a vehicle for exposure of humans to pathogens at beach sites, resulting in increased health risks. Sampling for microorganisms in sand should therefore be considered for inclusion in regulatory programmes aimed at protecting recreational beach users from infectious disease. Here, we review the literature on pathogen levels in beach sand, and their potential for affecting human health. In an effort to provide specific recommendations for sand sampling programmes, we outline published guidelines for beach monitoring programmes, which are currently focused exclusively on measuring microbial levels in water. We also provide background on spatial distribution and temporal characteristics of microbes in sand, as these factors influence sampling programmes. First steps toward establishing a sand sampling programme include identifying appropriate beach sites and use of initial sanitary assessments to refine site selection. A tiered approach is recommended for monitoring. This approach would include the analysis of samples from many sites for faecal indicator organisms and other conventional analytes, while testing for specific pathogens and unconventional indicators is reserved for high-risk sites. Given the diversity of microbes found in sand, studies are urgently needed to identify the most significant aetiological agent of disease and to relate microbial measurements in sand to human health risk.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

The orbital ordering in perovskite-type vanadium oxides, RVO3 (R: rare earth), has been investigated by resonant X-ray scattering (RXS) near the V K-edge energy. The G-type orbital order, C-type orbital order and orbital disorder phases are elucidated on the basis of the azimuthal-angle and polarization dependence of the RXS signal reflecting the orbital ordering.

Leakage currents through MIS (Metal Insulator Semiconductor) structures with several ultra-thin (14–30Å) insulators (silicon dioxide, silicon oxynitride, and silicon nitride) have been investigated. The leakage currents through both dioxide and oxynitride films sandwiched between n-type poly-Si gates and n-type substrates can be well fitted by the equation for the electron direct tunneling mechanism using the same effective mass and barrier height. This result indicates that incorporation of a minute amount of nitrogen atoms does not seriously affect the basic electrical properties of the oxide films. Leakage currents through ultra-thin nitride can te also fitted with the equation for the direct tunneling mechanism without assuming any extra conduction mechanisms such as hopping through defects.