Comparative analysis of two models for phonon polaritons in van der Waals materials: 2D and 3D.

Phonon polaritons with ultralow losses and high confinement in extremely anisotropic media have opened up new avenues for manipulating the flow of light at the nanoscale. Recent advances in var der Waals (vdW) materials reveal unprecedented dispersion characteristics of polaritons using a two-dimensional (2D) model, treating the slab as a surface without thickness. However, the difference between the 2D and three-dimensional (3D) models of hyperbolic polaritons remains largely unexplored.

Comparative analysis of two models for the optical response of a thin slab: a film of finite thickness a surface current sheet.

An accurate description of the electromagnetic properties of materials is fundamental to optical and electric devices. As a current research hotspot, thin slabs generally are modeled as a film of finite thickness with a dielectric function. However, inspired by two-dimensional materials, thin slabs can be regarded as surface current sheets with conductivity.

Surface and volume phonon polaritons in a uniaxial hyperbolic material: optic axis parallel versus perpendicular to the surface.

Uniaxial hyperbolic materials enable excitation of phonon polaritons with utrahigh wavevectors that have been shown to be promising for many optical and thermal radiative applications and thus have attracted much attention recently. However, the characteristics of surface and volume phonon polaritons excited with uniaxial hyperbolic materials that exhibit in-plane anisotropy or in-plane isotropy have not been discussed thoroughly and some issues have so far remained elusive. In this paper, we conducted a comprehensive investigation on surface and volume phonon polaritons in a bulk or a thin slab of hexagonal boron nitride (hBN).

Multiband selective absorbers made of 1D periodic Ag/SiO/Ag core/shell coaxial cylinders horizontally lying on a planar substrate.

In this paper, we present a one-dimensional periodic microstructure for multiband selective absorbers of thermal radiation. The microstructure is made of Ag/SiO/Ag core/shell coaxial cylinders horizontally lying on top of a SiO dielectric spacer and an opaque silver substrate. The spectral-directional absorptivity of the proposed structure was numerically investigated with the finite element based Comsol Multiphysics software.

[Hemodynamic analyses of large intracranial aneurysms].

Objective: To simulate the computational hemodynamics of large intracranial aneurysms and analyze the hemodynamics of three types of large intracranial aneurysms.

Methods: A total of 32 patient-specific models of large intracranial aneurysms were constructed with the data of DSA (digital subtraction angiography). According to the location of outflow vessel, plane of main vortex and impact zone, large intracranial aneurysms were classified into type A (outflow vessel in the plane of main vortex), type B1 (outflow vessel out of plane of main vortex, impact zone at the lateral wall of aneurysm) and type B2 (outflow vessel out of plane of main vortex, impact zone at the dome of aneurysm).

Modeling calcium wave based on anomalous subdiffusion of calcium sparks in cardiac myocytes.

Ca(2+) sparks and Ca(2+) waves play important roles in calcium release and calcium propagation during the excitation-contraction (EC) coupling process in cardiac myocytes. Although the classical Fick's law is widely used to model Ca(2+) sparks and Ca(2+) waves in cardiac myocytes, it fails to reasonably explain the full-width at half maximum(FWHM) paradox. However, the anomalous subdiffusion model successfully reproduces Ca(2+) sparks of experimental results.

Slip-flow and heat transfer of a non-newtonian nanofluid in a microtube.

The slip-flow and heat transfer of a non-Newtonian nanofluid in a microtube is theoretically studied. The power-law rheology is adopted to describe the non-Newtonian characteristics of the flow, in which the fluid consistency coefficient and the flow behavior index depend on the nanoparticle volume fraction. The velocity profile, volumetric flow rate and local Nusselt number are calculated for different values of nanoparticle volume fraction and slip length.

Blood flow and macromolecular transport in complex blood vessels.

Numerical simulations of pulsatile flows and macromolecular (such as LDL) transport in complex blood vessels, including the cerebral artery, are carried out using the FLUENT software. The hemodynamic factors such as axial velocity, secondary flow as well as LDL concentration distribution in the complex vessel are obtained. It is found that in the case of pulsatile flow, the LDL concentration is higher in the central region of the flow than on the wall.

Brewster angle with a negative-index material.

The demonstration and confirmation of metamaterials with simultaneous negative permittivity and permeability, and thus a negative refractive index, has resulted in a surge of interest in the reflection and refraction phenomena at the interfaces of these so-called negative-index materials (NIMs). We present a systematic study of the Brewster angle, i.e.