Hyperspectral system for Imaging of skin chromophores and blood oxygenation

We developed a compact, fast, hand-held hyperspectral imaging system for 2D neural network-based visualization of skin chromophores and blood oxygenation. Here, we present results of the system tests on healthy volunteers

Ultrafast Hot-Carrier Dynamics in Ultrathin Monocrystalline Gold

Applications in photodetection, photochemistry, and active metamaterials and metasurfaces require fundamental understanding of ultrafast nonthermal and thermal electron processes in metallic nanosystems. Significant progress has been recently achieved in synthesis and investigation of low-loss monocrystalline gold, opening up opportunities for its use in ultrathin nanophotonic architectures. Here, we reveal fundamental differences in hot-electron thermalisation dynamics between monocrystalline and polycrystalline ultrathin (down to 10 nm thickness) gold films. Comparison of weak and strong excitation regimes showcases a counterintuitive unique interplay between thermalised and non-thermalised electron dynamics in mesoscopic gold with the important influence of the X-point interband transitions on the intraband electron relaxation. We also experimentally demonstrate the effect of hot-electron transfer into a substrate and the substrate thermal properties on electron-electron and electron-phonon scattering in ultrathin films. The hot-electron injection efficiency from monocrystalline gold into TiO2, approaching 9% is measured, close to the theoretical limit. These experimental and modelling results reveal the important role of crystallinity and interfaces on the microscopic electronic processes important in numerous applications.Comment: 9 pages, 4 figure

Second harmonic generation in multilayer graphene induced by direct electric current

Optical second harmonic generation (SHG) is studied from multilayer graphene films in the presence of DC electric current flowing in the sample plane. Graphene layers are manufactured by chemical vapour deposition (CVD) technique and deposited on an oxidised Si(001) substrate. SHG intensity from graphene layer is found to be negligible in the absence of the DC current, while it increases dramatically with the application of the electric current. The current-induced change of the SHG intensity rises linearly with the current amplitude and changes its sign under the reversal of the current direction to the opposite. The observed effect is explained in terms of the interference of second harmonic radiation reflected from the Si surface and that induced by the DC current in multilayer graphene

Advances in Dynamic Light Scattering Imaging of Blood Flow

Dynamic light scattering (DLS) is a well known experimental approach uniquely suited for the characterization of small particles undergoing Brownian motion in randomly inhomogeneous turbid scattering medium, including water suspension, polymers in solutions, cells cultures, and so on. DLS is based on the illuminating of turbid medium with a coherent laser light and further analyzes the intensity fluctuations caused by the motion of the scattering particles. The DLS-based spin-off derivative techniques, such laser Doppler flowmetry (LDF), diffusing wave spectroscopy (DWS), laser speckle contrast imaging (LSCI), and Doppler optical coherence tomography (DOCT), are exploited widely for non-invasive imaging of blood flow in brain, skin, muscles, and other biological tissues. The recent advancements in the DLS-based imaging technologies in frame of their application for brain blood flow monitoring, skin perfusion measurements, and non-invasive blood micro-circulation characterization are overviewed. The fundamentals, breakthrough potential, and practical findings revealed by DLS-based blood flow imaging studies, including the limitations and challenges of the approach such as movement artifacts, non-ergodicity, and overcoming high scattering properties of studied medium, are also discussed. It is concluded that continued research and further technological advancements in DLS-based imaging will pave the way for new exciting developments and insights into blood flow diagnostic imaging

Beyond life: Exploring hemodynamic patterns in postmortem mice brains

We utilize Laser Speckle Contrast Imaging (LSCI) for visualizing cerebral blood flow in mice during and post-cardiac arrest. Analyzing LSCI images, we noted temporal blood flow variations across the brain surface for hours postmortem. Fast Fourier Transform (FFT) analysis depicted blood flow and microcirculation decay post-death. Continuous Wavelet Transform (CWT) identified potential cerebral hemodynamic synchronization patterns. Additionally, non-negative matrix factorization (NMF) with four components segmented LSCI images, revealing structural subcomponent alterations over time. This integrated approach of LSCI, FFT, CWT, and NMF offers a comprehensive tool for studying cerebral blood flow dynamics, metaphorically capturing the ‘end of the tunnel’ experience. Results showed primary postmortem hemodynamic activity in the olfactory bulbs, followed by blood microflow relocations between somatosensory and visual cortical regions via the superior sagittal sinus. This method opens new avenues for exploring these phenomena, potentially linking neuroscientific insights with mysteries surrounding consciousness and perception at life's end

Stokes-correlometry analysis of biological tissues with polycrystalline structure

Utilizing Stokes-correlometry analysis a new diagnostic approach has been introduced for quantitative assessment of polarization images of histological sections of optically anisotropic biological tissues with different morphological structures and physiological conditions. The developed approach is based on the quantitative assessment of coordinate and phase distributions of the Stokes vector of scattered light. A combined use of statistic, correlation, and fractal analysis is used for resolving variations in optical anisotropy of biological samples. The proposed combined application of the statistical, correlation, and fractal-based evaluates of spatial distributions of `single-point' polarization azimuth, ellipticity, and `two-point' Stokes vector parameters of polarization images of biological tissues histological sections demonstrates a high accuracy (Ac ≥ 90%) in monitoring of optical anisotropy variations within biological tissues

Family Reading in Children Literacy Skills Formation

At present, the decline in the youth environment's interest in reading is becoming a global social issue, since reading is one of the key tools for obtaining information. The student environment is of greatest concern, because it is precisely in student years that personal enhancement takes place, and the general cultural, informational, reading and communicative competences of a person are formed. These competences, including the ability to solve intellectual problems and problems in writing, the abilityф to work with a variety of texts in different languages, are necessary for contemporary people both in professional activities and in their private life. In this regard, the issue of family reading is acute, as reading skills are laid in preschool age. So, the purpose of our research is to identify the reasons for the decline in   reading's interest, as well as to determine the conditions ensuring a positive dynamics in this area. The article presents the results of the survey of 284 schoolchildren and students - future teachers aged 16 to 23 years. It is revealed that 76.8% of respondents consider the preserving the family reading traditions in children's upbringing to be an actual problem which speaks about the need of activity among the youth to increase motivation for family reading. Only about half of the respondents were able to give concrete recommendations for literary works for joint reading by all members of the family. On the one hand, this suggests that universities need systematic educational work among students to increase motivation for reading in general, and to family reading in particular. On the other hand, this problem concerns the entire society as well