The papillary dermis of human skin is responsible for its biomechanical properties and for supply of epidermis with chemicals. Dermis is mainly composed of structural protein molecules, including collagen and elastin, and contains blood capillaries. Connective tissue diseases, as well as cardiovascular complications have manifestations on the molecular level in the papillary dermis (e.g. alteration of collagen I and III content) and in the capillary structure. In this paper we assessed the molecular structure of internal and external regions of skin capillaries using two-photon fluorescence lifetime imaging (FLIM) of endogenous compounds. It was shown that the capillaries are characterized by a fast fluorescence decay, which is originated from red blood cells and blood plasma. Using the second harmonic generation signal, FLIM segmentation was performed, which provided for spatial localization and fluorescence decay parameters distribution of collagen I and elastin in the dermal papillae. It was demonstrated that the lifetime distribution was different for the inner area of dermal papillae around the capillary loop that was suggested to be due to collagen III. Hence, we propose a generalized approach to two-photon imaging of the papillary dermis components, which extends the capabilities of this technique in skin diagnosis.
Cyanobacteria bloom is a great ecological problem of Curonian Lagoon and Baltic Sea. The development of novel methods for the on-line control of cyanobacteria concentration and, moreover, for prediction of bloom spreading is of interest for monitoring the state of ecosystem. Here, we report the results of the joint application of hyperspectral measurements and remote sensing of Curonian Lagoon in July 2015 aimed at the assessment of cyanobacteria communities. We show that hyperspectral data allow on-line detection and qualitative estimation of cyanobacteria concentration, while the remote sensing data indicate the possibility of cyanobacteria bloom detection using the spectral features of upwelling irradiation.
The possibilities of laser nanosecond fluorometry in the diagnostics of humic substances (HSs) are investigated. A conclusion on the quantity of fluorophores that determine the HS fluorescence kinetics is drawn. The differences in the molecular photophysical parameters are revealed and measured for HSs of different genesises.
The mechanism of formation of the optical properties of dissolved organic matter (DOM) and humic substances (HS) is still a challenging problem in optical spectroscopy and environmental science. Decades of research have formed the list of spectral properties common to DOM and HS, which are impossible to mimic with individual molecular fluorophores and chromophores. Here we show that humic-like optical properties can be reproduced by the heterogeneous systems of chromophores that appear as a result of oxidation of simple aromatic species. To illustrate this fact, features of the steady-state and time-resolved optical response, as well as molecular composition, were studied during the oxidation of tryptophan and dihydroxybenzoic acid in aqueous solutions. The generated mixture of oxidation products exhibited visible absorption and fluorescence almost similar to those of DOM and HS, yet minor discrepancies with an HS-like optical response could be revealed by borohydride reduction and changes in the pH of the studied systems. The suggested generalized framework of the formation of humic-like optical properties can be further extended to other classes of systems and serve as the basis for investigating DOM and HS photophysics on simpler models.
Some peculiarities of phytoplankton fluorescence which were observed in coastal waters of the Black Sea (near Gelendzhik) in Aug-Sept 1997, 1998 and 1999 are discussed. Possibilities for the development of a method of water quality bio-indication based on phytoplankton photophysical parameter measurements are reported. A 3-parametric model describing the process of phytoplankton fluorescence formation is considered. Theoretical approximate expressions for generalised parameters are obtained. These expressions indicate the possibility of using generalised parameters for water quality bio-indication.
Variations in salinity and nitrogen concentration in the aquatic environment are among the observed effects of global climate change. They affect the structure of phytoplankton communities and the physiological state of algae and cyanobacteria. Results of laboratory studies of these effects are presented. A combination of Nonlinear Laser Fluorimetry (NLF) and Fluorescence Induction and Relaxation (FIRe) fluorimetry is used to evaluate the photophysical parameters of photosystem II and Chlorophyll a in native samples of the diatom algae Thalassiosira weissflogii, the zooxanthellae Symbiodium sp. CCMP 2467, and the cyanobacteria Synechococcus sp. CCMP 1379, grown under different salinity (40, 18, and 5 psu) and nitrogen concentration (normal, ×0.5, ×2). Cyanobacteria are shown to be most resistant to these variations, while zooxanthellae are the most sensitive species. This suggests that an effect of global climate change on the phytoplankton community might be the transformation of its structure towards an increasing role of cyanobacteria. Another alarming outlook is the negative impact of climate change on the physiological state of corals, which live in symbiotic relationship with zooxanthellae. This suggests that the reasons for the degradation of coral reefs are not entirely anthropogenic. It is suggested that coral reef monitoring of variations in the photophysical characteristics of zooxanthellae might be one of the most effective ways for detecting the influence of global climate change on marine biota in early stages. It is advisable to monitor coral reefs in the oceanic areas with lowest anthropogenic impact as background stations for climate change monitoring.
A shore-based lidar, which plays a vital role in the creation of continuous express monitoring of coastal sea water areas, is described. The results of testing in the region of the Blue Bay (Black Sea, near Gelendzhik) are reported. Echo-signal spectra were recorded by exciting water by light at wavelengths 532, 355 and 266 nm (second, third and fourth harmonics of a Nd:YAG laser). The dependence of the echo signal (Raman scattering of light by water molecules) on the sensing range is studied. The obtained results are in good agreement with the theory of remote laser sensing developed in this work for large sensing angles, in which the wind waves play a key role. A sensing range of 100 m was achieved using 532-nm, 10-ns laser pulses at a pulse repetition rate of 10 Hz and the pulse energy of 10 mJ. The possibility of increasing the sensing range to 0.5–1 km is shown.
'/%3e%3cpath id='b' d='M658.84 441.31c-7.618 16.446-22.845 19.271-36.164 5.995 0 0 5.354-3.783 11.086-4.826-1.075-4.574 1.13-10.902 4.235-14.324 3.258 2.227 7.804 6.689 8.96 11.874 8.03-1.04 11.883 1.282 11.883 1.282z'/%3e%3cuse xlink:href='%23b' transform='rotate(9.37 700 804)'/%3e%3cuse xlink:href='%23b' transform='rotate(18.74 700 804)'/%3e%3cpath fill='none' stroke='%23f8c300' stroke-width='16' d='M603 478a340 340 0 0 1 194 0'/%3e%3cg transform='translate(700 380)'%3e%3cg transform='translate(0 -140)'%3e%3cpath id='c' d='m0-513674 301930 929245-790463-574305h977066l-790463 574305z' transform='scale(.00005)'/%3e%3c/g%3e%3cg id='d'%3e%3cuse xlink:href='%23c' transform='translate(-70 -121.244)'/%3e%3cuse xlink:href='%23c' transform='translate(-121.244 -70)'/%3e%3cuse xlink:href='%23c' transform='translate(-140)'/%3e%3c/g%3e%3cuse xlink:href='%23d' transform='scale(-1 1)'/%3e%3c/g%3e%3c/g%3e%3c/svg%3e)
