Stiffness of RBC optical confinement affected by optical clearing

In vivo optical trapping is a novel applied direction of an optical manipulation, which enables one to noninvasive measurement of mechanical properties of cells and tissues in living animals directly. But an application area of this direction is limited because strong scattering of many biological tissues. An optical clearing enables one to decrease the scattering and therefore increase a depth of light penetration, decrease a distortion of light beam, improve a resolution in imaging applications. Now novel methods had appeared for a measurement an optical clearing degree at a cellular level. But these methods aren’t applicable in vivo. In this paper we present novel measurement method of estimate of the optical clearing, which are based on a measurement of optical trap stiffness. Our method may be applicable in vivo

Recent progress in tissue enhanced spectroscopy for cancer detection

Spectroscopy methods can be used for pathology identification and monitoring, but their applications are limited by light scattering if the disease is located in deeper tissue layers. The first study presented in this paper shows that the simple application of spectroscopy measurements allows colorectal cancer discrimination through the identification of different pigment content in normal and diseased tissues. The other two studies demonstrate that by combining sensitive spectroscopy measurements in a wide spectral range with optical clearing (OC) treatments is also useful for cancer discrimination. In the second study, by using spectral collimated transmittance (Tc) measurements during OC treatments, it was possible to estimate the diffusion coefficient of glucose in normal and pathological colorectal mucosa as: Dglucose = 5.8×10-7 cm2/s and Dglucose = 4.4×10-7 cm2/s, respectively. An additional result of this study shows that the mobile water content is about 5% higher in pathological mucosa. In the third study, by analyzing the OC efficiency in the deep UV range, it was possible to obtain different protein dissociation rates in normal (27.4) and pathological (79.1) mucosa tissues at 93%-glycerol treatment. Such methods can be applied to study other types of cancer or other diseases, and their conversion into noninvasive procedures, based on diffuse reflectance spectroscopy, is to be expected. © Anita Publications. All rights reserved.info:eu-repo/semantics/publishedVersio

Quarkonium dissociation in quark-gluon plasma via ionization in magnetic field

We study the impact of magnetic fields generated in relativistic heavy ion collisions on the decay probability of quarkonium produced in the central rapidity region. The quark and anti-quark components are subject to mutually orthogonal electric and magnetic fields in the quarkonium comoving frame. In the presence of an electric field, quarkonium has finite dissociation probability. We use the WKB approximation to derive the dissociation probability. We found that quarkonium dissociation energy, i.e. the binding energy at which dissociation probability is of order unity, increases with the magnetic field strength. It also increases with quarkonium momentum in the laboratory frame due to Lorentz boost of electric field in the comoving frame. As a consequence, J/Psi in plasma dissociates at lower temperature then it would be in the absence of a magnetic field. We argue that J/Psi's produced in heavy-ion collisions at LHC with P_T>9GeV would dissociate even in vacuum. In plasma, J/Psi dissociation in magnetic field is much stronger due to decrease of its binding energy with temperature. We discuss the phenomenological implications of our results.Comment: 16 pages, 4 figures; v2: discussion and references added, typos fixed; v3: discussion section expande

Beer-Lambert law along non-linear mean light pathways for the rational analysis of Photoplethysmography

Photoplethysmography (PPG) is a technique that uses light to noninvasively obtain a volumetric measurement of an organ with each cardiac cycle. A PPG-based system emits monochromatic light through the skin and measures the fraction of the light power which is transmitted through a vascular tissue and detected by a photodetector. Part of thereby transmitted light power is modulated by the vascular tissue volume changes due to the blood circulation induced by the heart beating. This modulated light power plotted against time is called the PPG signal. Pulse Oximetry is an empirical technique which allows the arterial blood oxygen saturation (SpO2 – molar fraction) evaluation from the PPG signals. There have been many reports in the literature suggesting that other arterial blood chemical components molar fractions and concentrations can be evaluated from the PPG signals. Most attempts to perform such evaluation on empirical bases have failed, especially for components concentrations. This paper introduces a non-empirical physical model which can be used to analytically investigate the phenomena of PPG signal. Such investigation would result in simplified engineering models, which can be used to design validating experiments and new types of spectroscopic devices with the potential to assess venous and arterial blood chemical composition in both molar fractions and concentrations non-invasively

UV-NIR efficiency of the refractive index matching mechanism on colorectal muscle during treatment with different glycerol osmolarities

The evaluation of the optical clearing mechanisms in tissues provides information about the efficiency of the clearing treatment. One of such mechanisms is the refractive index matching, which is created by the partial replacement of tissue water by an optical clearing agent with higher refractive index, better matched to the index of tissue scatterers. With the objective of evaluating the refractive index matching mechanism for a wide spectral range and comparing its magnitude between treatments with different clearing agent osmolarities, thickness and collimated transmittance measurements were obtained from human colorectal muscle samples under treatment with 20%-, 40% and 60%-glycerol. Such measurements were used in a calculation model to obtain the refractive index kinetics for the interstitial fluid and for the whole tissue. The calculation results show that the refractive index matching has a stronger effect in the ultraviolet and that such matching is more effective for higher agent concentrations in the treating solutions.This research was supported by the Portuguese Grant FCT UIDB/04730/2020. VVT was supported by the grant of the Russian Foundation of Basic Research #18-29-02060 MK.info:eu-repo/semantics/publishedVersio

Laser-induced generation of singlet oxygen and its role in the cerebrovascular physiology

For over 55 years, laser technology has expanded from laboratory research to widespread fields, for example telecommunication and data storage amongst others. Recently application of lasers in biology and medicine presents itself as one of the emerging areas. In this review, we will outline the recent advances in using lasers for the generation of singlet oxygen, traditionally used to kill tumour cells or induce thrombotic stroke model due to damage vascular effects. Over the last two decade, completely new results on cerebrovascular effects of singlet oxygen generated during photodynamic therapy (PDT) have been shown alongside promising applications for delivery of drugs and nanoparticles into the brain for therapy of brain cancer. Furthermore, a "gold key” has been found to overcome the limitations of PDT, such as low light penetration and high toxicity of photosensitizers, by direct generation of singlet oxygen using quantum-dot laser diodes emitting in the near infrared (NIR) spectral range. It is our motivation to highlight these pioneering results in this review, to improve understanding of the biological role of singlet oxygen and to provide new perspectives for improving clinical application of laser based therapy in further research