Study of anisotropic thermal conductivity in textured thermoelectric alloys by Raman spectroscopy.

Polycrystalline p-type Sb1.5Bi0.5Te3 (SBT) and n-type Bi2Te2.7Se0.3 (BTS) compounds possessing layered crystal structure show anisotropic electronic and thermal transport properties. This research is in pursuit of better understanding the anisotropic thermal properties using Raman spectroscopy. A systematic Raman spectroscopic study of the hot-pressed pellet of the textured p-type SBT and n-type BTS is reported in both directions: parallel (‖) and perpendicular (⊥) to the pressing axis as a function of temperature and laser power. The first-order temperature coefficient, optical thermal conductivity, and phonon lifetime are qualitatively determined from the temperature and laser power-dependent frequency and full-width half maximum (FWHM) of Raman peaks (A1 1g, E2 g & A2 1g). Anisotropy in experimental phonon thermal conductivity in both directions is correlated with the approximated optical thermal conductivity, phonon lifetime and phonon anharmonicity. The anisotropy in phonon anharmonicity in both directions is explained by the modified Klemens-Hart-Aggarwal-Lax phonon decay model. In this study, the symmetric three-phonon scattering process is considered responsible for thermal transport in the temperature range of 300 to 473 K.

A robust sebum, oil, and particulate pollution model for assessing cleansing efficacy of human skin.

With increasing concerns over the rise of atmospheric particulate pollution globally and its impact on systemic health and skin ageing, we have developed a pollution model to mimic particulate matter trapped in sebum and oils creating a robust (difficult to remove) surrogate for dirty, polluted skin. OBJECTIVE: To evaluate the cleansing efficacy/protective effect of a sonic brush vs. manual cleansing against particulate pollution (trapped in grease/oil typical of human sebum). METHODS: The pollution model (Sebollution; sebum pollution model; SPM) consists of atmospheric particulate matter/pollution combined with grease/oils typical of human sebum. Twenty subjects between the ages of 18-65 were enrolled in a single-centre, cleansing study comparisons between the sonic cleansing brush (normal speed) compared to manual cleansing. Equal amount of SPM was applied to the centre of each cheek (left and right). Method of cleansing (sonic vs. manual) was randomized to the side of the face (left or right) for each subject. Each side was cleansed for five-seconds using the sonic cleansing device with sensitive brush head or manually, using equal amounts of water and a gel cleanser. Photographs (VISIA-CR, Canfield Imaging, NJ, USA) were taken at baseline (before application of the SPM), after application of SPM (pre-cleansing), and following cleansing. Image analysis (ImageJ, NIH, Bethesda, MD, USA) was used to quantify colour intensity (amount of particulate pollutants on the skin) using a scale of 0 to 255 (0 = all black pixels; 255 = all white pixels). Differences between the baseline and post-cleansing values (pixels) are reported as the amount of SPM remaining following each method of cleansing. RESULTS: Using a robust cleansing protocol to assess removal of pollutants (SPM; atmospheric particulate matter trapped in grease/oil), the sonic brush removed significantly more SPM than manual cleansing (P < 0.001). While extreme in colour, this pollution method easily allows assessment of efficacy through image analysis.

LBM-EP: Lattice-Boltzmann method for fast cardiac electrophysiology simulation from 3D images.

Current treatments of heart rhythm troubles require careful planning and guidance for optimal outcomes. Computational models of cardiac electrophysiology are being proposed for therapy planning but current approaches are either too simplified or too computationally intensive for patient-specific simulations in clinical practice. This paper presents a novel approach, LBM-EP, to solve any type of mono-domain cardiac electrophysiology models at near real-time that is especially tailored for patient-specific simulations. The domain is discretized on a Cartesian grid with a level-set representation of patient's heart geometry, previously estimated from images automatically. The cell model is calculated node-wise, while the transmembrane potential is diffused using Lattice-Boltzmann method within the domain defined by the level-set. Experiments on synthetic cases, on a data set from CESC'10 and on one patient with myocardium scar showed that LBM-EP provides results comparable to an FEM implementation, while being 10 - 45 times faster. Fast, accurate, scalable and requiring no specific meshing, LBM-EP paves the way to efficient and detailed models of cardiac electrophysiology for therapy planning.