Dielectric study of side-chain liquid crystalline polyazomethine/fullerene C<Subscript>60</Subscript> nanocomposite

For side-chain liquid crystalline polyazomethine/fullerene C₆₀ nanocomposite (C₆₀ loading is 0.25 wt%), both real and imaginary components of the dielectric permittivity were investigated in wide regions of temperature and frequency. Analysis of frequency dependent permittivity allowed finding three relaxations (α, β ₁ and β ₂) in the nanocomposite. They were attributed to specific modes of molecular mobility. β-relaxations were described with the Arrhenius equation, whereas α-relaxation was described with the Vogel-Fulcher-Tammann equation. Anti-plasticization effect of the C₆₀ doping was shown to be manifested as an increase of the glass transition temperature of the nanocomposite as compared with that of the neat polymer.     

Enhanced calcium–magnesium–aluminosilicate (CMAS) resistance of GdAlO3 (GAP) for composite thermal barrier coatings

The impact of calcium–magnesium–alumino-silicate (CMAS) degradation is a critical factor for development of new thermal and environmental barrier coatings. Several methods of preventing damage have been explored in the literature, with formation of an infiltration inhibiting reaction layer generally given the most attention. Gd₂Zr₂O₇ (GZO) exemplifies this reaction with the rapid precipitation of apatite when in contact with CMAS. The present study compares the CMAS behavior of GZO to an alternative thermal barrier coating (TBC) material, GdAlO₃ (GAP), which possesses high temperature phase stability through its melting point as well as a significantly higher toughness compared with GZO. The UCSB laboratory CMAS (35CaO–10MgO–7Al₂O₃–48SiO₂) was utilized to explore equilibrium behavior with 50:50 mol% TBC:CMAS ratios at 1200, 1300, and 1400°C for various times. In addition, 8 and 35 mg/cm² CMAS surface exposures were performed at 1425°C on dense pellets of each material to evaluate the infiltration and reaction in a more dynamic test. In the equilibrium tests, it was found that GAP appears to dissolve slower than GZO while producing an equivalent or higher amount of pore blocking apatite. In addition, GAP induces the intrinsic crystallization of the CMAS into a gehlenite phase, due in part to the participation of the Al₂O₃ from GAP. In surface exposures, GAP experienced a substantially thinner reaction zone compared with GZO after 10 h (87 ± 10 vs. 138 ± 4 μm) and a lack of strong sensitivity to CMAS loading when tested at 35 mg/cm² after 10 h (85 ± 13 versus 246 ± 10 μm). The smaller reaction zone, loading agnostic behavior, and intrinsic crystallization of the glass suggest this material warrants further evaluation as a potential CMAS barrier and inclusion into composite TBCs.     

Filler effect on formation and properties of interpenetrating polymer networks based on polyurethane and polyesteracrylate

The formation processes of unfilled and filled interpenetrating polymer networks (IPNs) and some of their physico-mechanical properties have been investigated. The IPN formation kinetics and the constituent network curing rates determine the rate and degree of microphase separation. This in turn determines the boundary layer composition and structure. Introduction of filler into the IPN during formation affects greatly the crosslinking reaction and the microphase segregation of homopolymers. It has been shown that the degree of phase segregation in filled IPNs differs from that in unfilled ones. All the fillers were found to shorten the time of internal stress appearance and to increase its value for IPNs with predominantly high-modulus component content. Some filled IPNs were shown to have greater thermodynamic stability than unfilled ones.     

Chitosan-based fiber-sponge materials as a promising tool for microalgae harvesting from Lake Baikal

Mass eutrophication of microalgae and cyanobacteria is observed in Lake Baikal in the past decade. In this paper, the concept of replaceable adsorption filter material based on chitosan flocculant filler and chlorinated polyvinyl chloride polymer nonwoven material are proposed. Functional and mechanical properties and morphology of the material are investigated depending on a packing density and a degree of chitosan filling. The introduction of 45% chitosan increases the Young's modulus up to 10 times, and it makes the material more rigid in 2.8 times. The high efficiency of sorption and growth inhibition of cumulative biomass culture was shown. The biomass source is taken from the coast of Barguzinsky Bay of Lake Baikal. Dominant species is microalgae of Scenedesmus genus.     

Combined speciation analysis by X-ray absorption near-edge structure spectroscopy, ion chromatography, and solid-phase microextraction gas chromatography-mass spectrometry to evaluate biotreatment of concentrated selenium wastewaters

In this study we evaluate the potential of anaerobic granular sludge as an inoculum for the bioremediation of selenium-contaminated waters using species-specific analytical methods. Solid species formed by microbial reduction were investigated using X-ray absorption near-edge structure (XANES) spectroscopy at the selenium K-edge. Furthermore, dissolved selenium species were specifically determined by ion chromatography (IC) and solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). Least-squares linear combination of the XANES spectra for samples incubated with the highest selenate/selenite concentrations (10(-3) M) show the predominance of elemental selenium and a Se(-I) selenide, such as ferroselite, the thermodynamically most stable iron selenide. In contrast, elemental selenium and Se(-II) selenides are the main species detected at the lower selenate/selenite concentrations. In each repeated fed batch incubation, most aqueous selenite anions were converted into solid selenium species, regardless of the type of electron donor used (acetate or H(2)/CO(2)) and the selenium concentration applied. On the other hand, at higher concentrations of selenate (10(-4) and 10(-3) M), significant amounts of the oxyanion remained unconverted after consecutive incubations. SPME-GC-MS demonstrated selenium alkylation with both electron donors investigated, as dimethyl selenide (DMSe) and dimethyl diselenide (DMDSe). Selenite was even more alkylated in the presence of H(2)/CO(2) (maximum 2156 μg of Se/L of DMSe + DMDSe) as compared to acetate (maximum 50 μg of Se/L). In contrast, selenate was less alkylated using both electron donors (maximum 166 and 3 μg of Se/L, respectively). The high alkylation potential for selenite limits its bioremediation in selenium laden waters involving H(2)/CO(2) as the electron donor despite the fact that nontoxic elemental selenium and thermodynamically stable metal selenide species are formed.     

The Adhesion‐Enhanced Contact Electrification and Efficiency of Triboelectric Nanogenerators

In the present work, the contact electrification of polymers that differ in adhesion strength is studied. Electrical current is measured along with adhesion in macroscale contacting‐separation experiments. Additionally, local adhesion and roughness are studied with atomic force microscopy to get deeper insight into relations between surface properties and electrification. Measurements reveal that higher surface charge is formed on more adhesive surfaces, thus confirming covalent bond cleavage as a mechanism for contact electrification of polymers. Investigated materials possess enhanced contact electrification making them attractive candidates for the conversion of mechanical energy to electrical in triboelectric nanogenerator devices.     

Detection of endogenous Snf1 and its activation state: application to Saccharomyces and Candida species

The stress-response Snf1 protein kinase of Saccharomyces cerevisiae serves as a powerful model for studies of the eukaryotic Snf1/AMP-activated protein kinase (AMPK) family. Central to studies of Snf1 are methods that determine its activation state under various physiological and genetic conditions. Here, we have developed a convenient and sensitive method for immunoblot analysis of endogenous yeast Snf1 and its activation-loop threonine (Thr210) phosphorylation. The method employs readily obtainable reagents and yields results that faithfully reflect the environmental and genetic conditions tested. Using our method, we have obtained evidence that Snf1 remains stress-regulated in reg1 Delta cells, revealing the existence of a Snf1 signalling mechanism(s) that is independent of Reg1-PP1 phosphatase. In addition to strains of common laboratory S. cerevisiae backgrounds, we have applied the method to two pathogenic Candida species, C. glabrata and C. albicans. We have detected proteins whose gel mobilities, immune properties and regulation patterns are consistent with those expected for the corresponding Snf1 homologues. Because Snf1 activation is a sensitive marker of several types of stress, including artifactual stresses associated with common cell harvesting and protein extraction procedures, the convenient and efficient protein extraction method described here should be advantageous for SDS-PAGE and immunoblot analyses of stress-regulated and other proteins from various yeast species.     

Drosophila as a Model System for Studying of the Evolution and Functional Specialization of the Y Chromosome

The Y chromosome is one of the sex chromosomes found in males of animals of different taxa, including insects and mammals. Among all chromosomes, the Y chromosome is characterized by a unique chromatin landscape undergoing dynamic evolutionary change. Being entirely heterochromatic, the Y chromosome as a rule preserves few functional genes, but is enriched in tandem repeats and transposons. Due to difficulties in the assembly of the highly repetitive Y chromosome sequence, deep analyses of Y chromosome evolution, structure, and functions are limited to a few species, one of them being Drosophila melanogaster. Despite Y chromosomes exhibiting high structural divergence between even closely related species, Y-linked genes have evolved convergently and are mainly associated with spermatogenesis-related activities. This indicates that male-specific selection is a dominant force shaping evolution of Y chromosomes across species. This review presents our analysis of current knowledge concerning Y chromosome functions, focusing on recent findings in Drosophila. Here we dissect the experimental and bioinformatics data about the Y chromosome accumulated to date in Drosophila species, providing comparative analysis with mammals, and discussing the relevance of our analysis to a wide range of eukaryotic organisms, including humans.     

Interferon-β Activity Is Affected by S100B Protein

Interferon-β (IFN-β) is a pleiotropic cytokine secreted in response to various pathological conditions and is clinically used for therapy of multiple sclerosis. Its application for treatment of cancer, infections and pulmonary diseases is limited by incomplete understanding of regulatory mechanisms of its functioning. Recently, we reported that IFN-β activity is affected by interactions with S100A1, S100A4, S100A6, and S100P proteins, which are members of the S100 protein family of multifunctional Ca²⁺-binding proteins possessing cytokine-like activities (Int J Mol Sci. 2020;21(24):9473). Here we show that IFN-β interacts with one more representative of the S100 protein family, the S100B protein, involved in numerous oncological and neurological diseases. The use of chemical crosslinking, intrinsic fluorescence, and surface plasmon resonance spectroscopy revealed IFN-β binding to Ca²⁺-loaded dimeric and monomeric forms of the S100B protein. Calcium depletion blocks the S100B–IFN-β interaction. S100B monomerization increases its affinity to IFN-β by 2.7 orders of magnitude (equilibrium dissociation constant of the complex reaches 47 pM). Crystal violet assay demonstrated that combined application of IFN-β and S100B (5–25 nM) eliminates their inhibitory effects on MCF-7 cell viability. Bioinformatics analysis showed that the direct modulation of IFN-β activity by the S100B protein described here could be relevant to progression of multiple oncological and neurological diseases.