Light field intensity distribution in three-dimensional polylactide scaffolds after irradiation with low-intensity light from one side of the samples has been determined in the visible and near-infrared regions of the spectrum. Two different types of scaffolds manufactured by the methods of supercritical fluid foaming and surface selective laser sintering have been investigated. The problem is solved by numerical calculation according to the Monte Carlo method involving experimentally obtained information about effective optical parameters of the scaffold material. Information about intensity distribution of the incident light in the matrix volume is needed to assess the radiation level for the scaffold cells after photobiostimulation. It has been shown that the formation of the light field in case of strongly scattering media, such as polylactide scaffolds, is determined by anisotropy g and the scattering coefficient μs.
A combination of approaches to the image analysis in cross-polarization optical coherence tomography (CP OCT) and high-resolution imaging by nonlinear microscopy and atomic force microscopy (AFM) at the different stages of atherosclerotic plaque development is studied. This combination allowed us to qualitatively and quantitatively assess the disorganization of collagen in the atherosclerotic arterial tissue (reduction and increase of CP backscatter), at the fiber (change of the geometric distribution of fibers in the second-harmonic generation microscopy images) and fibrillar (violation of packing and different nature of a basket-weave network of fibrils in the AFM images) organization levels. The calculated CP channel-related parameters are shown to have a statistically significant difference between stable and unstable (also called vulnerable) plaques, and hence, CP OCT could be a potentially powerful, minimally invasive method for vulnerable plaques detection.
Atomic Force Microscopy (AFM) gives a possibility to study and control the surface structure at submicron spatial
scales. The essential problem in studying the surfaces is their adequate parameterization. It is necessary to extract
information from the surface roughness profiles h(x) and h(y) along coordinates x and y. These profiles contain regular (resonant) components as well as chaotic (noisy) components with "long memory". The main questions are
how to extract useful information about the surface state and study the effect of various external factors on it by
analyzing the spatial series h(x) and h(y) and separate out the information contents of chaotic and resonant
components. These problems can be solved by using Flicker-Noise Spectroscopy (FNS) approach. According to
FNS, the information hidden in chaotic surface profiles is represented by correlation links in sequences of different
types of irregularities: spikes, jumps, and discontinuities in derivatives of different orders at all spatial hierarchical
levels of the systems. In this paper, the FNS is used to parameterize AFM images of sufficiently homogeneous
structures obtained for surfaces of lithium fluoride single crystals as well as two dendritic (treelike) structures
formed on mica surface from solutions of surfactant copolymers.