Publications by authors named "Alexander Tikhonov"

The WO photoanode has great potential application for solar photoelectrochemical water oxidation due to suitable band edge positions with water oxidation potentials. However, it suffers from poor light absorbance in the visible region. Here, we use Eu-doped YO nanoparticles (NPs) in combination with plasmonic gold (Au) NPs to better utilize and adsorb photons from UV and visible regions of sunlight.

View Article and Find Full Text PDF

Aging is interrelated with changes in red blood cell parameters and functionality. In this article, we focus on red blood cells (RBCs) and provide a review of the known changes associated with the characterization of RBC deformability in aging and related pathologies. The biophysical parameters complement the commonly used biochemical parameters and may contribute to a better understanding of the aging process.

View Article and Find Full Text PDF

This work represents an overview of electron transport regulation in chloroplasts as considered in the context of structure-function organization of photosynthetic apparatus in plants. Main focus of the article is on bifurcated oxidation of plastoquinol by the cytochrome bf complex, which represents the rate-limiting step of electron transfer between photosystems II and I. Electron transport along the chains of non-cyclic, cyclic, and pseudocyclic electron flow, their relationships to generation of the trans-thylakoid difference in electrochemical potentials of protons in chloroplasts, and pH-dependent mechanisms of regulation of the cytochrome bf complex are considered.

View Article and Find Full Text PDF

A transmembrane difference in the electrochemical potentials of protons (Δμ) serves as a free energy intermediate in energy-transducing organelles of the living cell. The contributions of two components of the Δμ (electrical, Δψ, and concentrational, ΔpH) to the overall Δμ value depend on the nature and lipid composition of the energy-coupling membrane. In this review, we briefly consider several of the most common instrumental (electrometric and EPR) methods for numerical estimations of Δψ and ΔpH.

View Article and Find Full Text PDF

Noble metal nanoparticles (NPs) are important in many applications, including light trapping of photovoltaic cells, photoelectrochemical applications, etc. The present study reports the formation of silver NPs from the as-deposited silver coatings on fused silica substrates by solid-state dewetting induced by high-current intense pulsed ion beam (IPIB) irradiation. We described the effects of IPIB irradiation with different ion beam current densities and numbers of pulses on NP morphology and compared the results with conventional rapid thermal annealing (RTA).

View Article and Find Full Text PDF

In oxygenic photosynthetic systems, the cytochrome bf (Cytbf) complex (plastoquinol:plastocyanin oxidoreductase) is a heart of the hub that provides connectivity between photosystems (PS) II and I. In this review, the structure and function of the Cytbf complex are briefly outlined, being focused on the mechanisms of a bifurcated (two-electron) oxidation of plastoquinol (PQH). In plant chloroplasts, under a wide range of experimental conditions (pH and temperature), a diffusion of PQH from PSII to the Cytbf does not limit the intersystem electron transport.

View Article and Find Full Text PDF

The prevalence and virulence of pathogens such as methicillin-resistant Staphylococcus (S.) aureus (MRSA), which can cause recurrent skin infections, are of significant clinical concern. Prolonged antibiotic exposure to treat or decolonize S.

View Article and Find Full Text PDF

This work is devoted to theoretical study of functioning of the cytochrome (Cyt) bf complex (plastoquinol:plastocyanin oxidoreductase) of the electron transport chain (ETC) in oxygenic photosynthesis. A composition of the chloroplast ETC and molecular mechanisms of functioning of the Cyt bf complex, which stands between photosystems II and I (PSII and PSI), are briefly reviewed. The Cyt bf complex oxidizes plastoquinol (PQH2) molecules formed in PSII, and reduces plastocyanin, which serves as an electron donor to PSI.

View Article and Find Full Text PDF

The photoelectrochemical (PEC) activity of metal oxide photoelectrodes for water-splitting applications can be boosted in several different ways. In this study, we showed that PEC activity can be significantly improved with a double-layer (crystalline-amorphous) configuration of WO thin films irradiated with intense pulsed ion beams (IPIB) of a nanosecond duration. It was found that IPIB irradiation promotes the formation of crystalline and sponge-like WO structures on the surface.

View Article and Find Full Text PDF

We present an approach to the noninvasive determination of the electron capacity of the intersystem pool of electron carriers in chloroplasts in situ. As apt experimental models, we used the leaves of Hibiscus rosa-sinensis and Tradescantia species. Electron paramagnetic resonance and optical response of P (the primary electron donor in Photosystem I) were applied to measuring electron transport in chloroplasts.

View Article and Find Full Text PDF

Purpose: To analyze the results of direct and transgenerational effects of radio frequency electromagnetic fields (RF-EMF) on the model organism of crustaceans .

Materials And Methods: were chronically exposed at 900 GHz EMF with an energy flux density (EFD) of about 1 mW/cm in the juvenile and pubertal periods of their ontogenesis. The cytotoxicity of exposure as well as survival, fertility and teratogenic effect of directly exposed daphnids and their progeny across three generations were analyzed.

View Article and Find Full Text PDF

Introduction: Coagulation parameters are important determinants for COVID-19 infection. We conducted meta-analysis to assess the association between early hemostatic parameters and infection severity.

Methods: Electronic search was made for papers that addressed clinical characteristics of COVID-19 patients and disease severity.

View Article and Find Full Text PDF

The additive manufacturing of metal parts takes up an increasing number of areas of mechanical engineering, but it still remains too expensive for mass use. Based on the experience in the production of combined metal-metal-polymer forming parts of molds, a new method for the production of composite parts from a metal shell filled with metal-polymer is proposed. As a basis for the study, strength calculations are given by the finite element method for the details of the exoskeleton and a sample of simplified geometry.

View Article and Find Full Text PDF

The review is focused on analysis of the mechanisms of temperature-dependent regulation of electron transport and ATP synthesis in chloroplasts of higher plants. Importance of photosynthesis thermoregulation is determined by the fact that plants are ectothermic organisms, whose own temperature depends on the ambient temperature. The review discusses the effects of temperature on the following processes in thylakoid membranes: (i) photosystem 2 activity and plastoquinone reduction; (ii) electron transfer from plastoquinol (via the cytochrome bf complex and plastocyanin) to photosystem 1; (iii) transmembrane proton transfer; and (iv) ATP synthesis.

View Article and Find Full Text PDF

Silver nanowire (AgNW) networks have attracted particular attention as transparent conductive films (TCF) due to their high conductivity, flexibility, transparency, and large scale processing compatible synthesis. As-prepared AgNW percolating networks typically suffer from high contact resistance, requiring additional post-synthetic processing. In this report, large area irradiation with 200 ns short intense pulsed ion beam (IPIB) was used to anneal and enhance the conductivity of AgNW network, deposited on temperature-sensitive polyethylene terephthalate (PET) substrate.

View Article and Find Full Text PDF

In this report, an improvement of the electrical performance and stability of a silver nanowire (AgNW) transparent conductive coating (TCC) is presented. The TCC stability against oxidation is achieved by coating the AgNWs with a polyvinyl alcohol (PVA) layer. As a result, a UV/ozone treatment has not affected the morphology of the AgNWs network and the PVA protection layer, unlike non-passivated TCC, which showed severe degradation.

View Article and Find Full Text PDF

The significance of temperature-dependent regulation of photosynthetic apparatus (PSA) is determined by the fact that plant temperature changes with environmental temperature. In this work, we present a brief overview of temperature-dependent regulation of photosynthetic processes in class B chloroplasts (thylakoids) and analyze these processes using a computer model that takes into account the key stages of electron and proton transport coupled to ATP synthesis. The rate constants of partial reactions were parametrized on the basis of experimental temperature dependences of partial photosynthetic processes: (1) photosystem II (PSII) turnover and plastoquinone (PQ) reduction, (2) the plastoquinol (PQH) oxidation by the cytochrome (Cyt) bf complex, (3) the ATP synthase activity, and (4) the proton leak from the thylakoid lumen.

View Article and Find Full Text PDF

Using thermoluminescence, PAM-fluorometry, and electron paramagnetic resonance (EPR) for assaying electron transport processes in chloroplasts in situ, we have compared photosynthetic characteristics in Tradescantia fluminensis leaves grown under low light (LL, 50-125 µmol photons m s) or high light (HL, 875-1000 µmol photons m s) condition. We found differences in the thermoluminescence (TL) spectra of LL- and HL-acclimated leaves. The LL and HL leaves show different proportions of the Q (~ 0 °C) and B (~ 25-30 °C) bands in their TL spectra; the ratios of the "light sums" of the Q and B bands being S/S ≈ 1/1 (LL) and S/S ≈ 1/3 (HL).

View Article and Find Full Text PDF

Using live microbes as therapeutic candidates is a strategy that has gained traction across multiple therapeutic areas. In the skin, commensal microorganisms play a crucial role in maintaining skin barrier function, homeostasis, and cutaneous immunity. Alterations of the homeostatic skin microbiome are associated with a number of skin diseases.

View Article and Find Full Text PDF

Tradescantia is a good model for assaying induction events in higher plant leaves. Chlorophyll (Chl) fluorescence serves as a sensitive reporter of the functional state of photosynthetic apparatus in chloroplasts. The fluorescence time-course depends on the leaf growth conditions and actinic light quality.

View Article and Find Full Text PDF

As one of the highest mobility semiconductor materials, carbon nanotubes (CNTs) have been extensively studied for use in field effect transistors (FETs). To fabricate surround-gate FETs- which offer the best switching performance-deposition of conformal, weakly-interacting dielectric layers is necessary. This is challenging due to the chemically inert surface of CNTs and a lack of nucleation sites-especially for defect-free CNTs.

View Article and Find Full Text PDF

In photosynthetic systems of oxygenic type, plastoquinone (PQ) molecules are reduced by photosystem II (PSII). The turnover of PQ determines the rate of PSII operation. PQ molecules are present in surplus with respect to PSII.

View Article and Find Full Text PDF

In this review, we consider the applications of electron paramagnetic resonance (EPR) methods to the study of the relationships between the electron transport and oxygen-exchange processes in photosynthetic systems of oxygenic type. One of the purposes of this article is to encourage scientists to use the advantageous EPR oximetry approaches to study oxygen-related electron transport processes in photosynthetic systems. The structural organization of the photosynthetic electron transfer chain and the EPR approaches to the measurements of molecular oxygen (O) with O-sensitive species (nitroxide spin labels and solid paramagnetic particles) are briefly reviewed.

View Article and Find Full Text PDF

In this work, we have compared photosynthetic characteristics of photosystem II (PSII) in Tradescantia leaves of two contrasting ecotypes grown under the low light (LL) and high light (HL) regimes during their entire growth period. Plants of the same genus, T. fluminensis (shade-tolerant) and T.

View Article and Find Full Text PDF

In this work, we investigated electron transport around the photosynthetic pigment-protein complex of Photosystem I (PS I) mediated by external high-potential electron carrier 2,3-dichloro-1,4-naphtoquinone (Cl NQ) and ascorbate. It has been demonstrated that the oxidized species of Cl NQ and ascorbate serve as intermediates capable of accepting electrons from the iron-sulfur cluster F of PS I. Reduced species of Cl NQ and ascorbate are oxidized by photooxidized PS I primary donor P700+ and/or by molecular oxygen.

View Article and Find Full Text PDF