Far Eastern Federal University

A chitosan hydrogel with tannic acid was obtained by introducing carboxymethylcellulose, which formed a polyelectrolyte complex with the cationic polysaccharide. The combination of electrostatic interactions and hydrogen bonds of the polyphenol with both polysaccharides resulted in dual crosslinking, which led to an almost thousand-fold increase in the mechanical strength of the hydrogel. Furthermore, tannic acid retained pronounced antimicrobial activity, which makes the developed hydrogel promising for biomedical applications such as wound dressings.

This paper presents an innovative method to control the apodized photonic bandgap spectrum (PBG) by modulating the refractive index of nonlinear refractive materials using a Gaussian beam. We analyze how the spectral properties of a one-dimensional photonic crystal (PC) composed of a harmonic structure and a layered PC change with the intensity and initial phase of the Gaussian beam. The materials of the PC structure are SiO2 and indium tin oxide nanoparticles (ITON), and the nonlinear refractive index nnl of ITON is 10− 7 cm2/W. In this paper, the transmission spectral characteristics of the harmonic structure and the layered PC structure are studied with and without the Gaussian control beam. The output power of the Gaussian beam used in the simulation is 200–300 mW. The results show that the apodized PC can change the PBG spectrum width, main frequency position of spectrum, and the appearance of narrowband defect modes, which suggests that the PC can be utilized as a sensor. The results of this study will open the way to new applications in photonic circuits, sensors, and communication technologies where precise control of light propagation is essential. This study will not only deepen the fundamental understanding of photonic materials, but also open new avenues for the development of next-generation photonic systems.

For development of the potential of nanosilica application in Portland cement concrete the effect in compressive strength R com increase was studied in the age from 1 to 360 d. Sol of hydrothermal nanosilica (HNS) solution produced by technology developed was used with SiO 2 particles Brunauer-Emmett-Teller surface area of 500 m 2/g. Concretes compositions were tested with liquid/binder ratio 0.5 and SiO 2 doses of cement replacement 0.5, 1, 2, and 3 wt.%. Modification of concrete with HNS sol provided a significant increase in compressive strength R com up to 86.4% (14.8%–43.9% at the age of 360 d) and high values of efficiency coefficient k ес 19.5–60.9 at the age of 28 d calculated using the relative increase of R com. Increase in compressive strength is characterized by an early gain in R com at the age of 1–7 d: the ratios R c o m 1 , 7 / R c o m 28 and R c o m 28 / R c o m 360 are higher in modified concrete. The obtained results can be used to model the hardening and predict the strength of modified concrete at the age of 2, 4, and 10 y. Results of the thermogravimetry, X-ray diffraction, scanning electron microscopy and water absorption methods provided explanations of pozzolanic reaction effects on compressive strength, water impermeability, abrasion and frost resistance, impact viscosity and durability were discussed. The dependence of k ec coefficient on SiO 2 dose and concrete’s age was analyzed. Using the coefficient k ec for different doses of SiO 2 at the age of 28 d, the corresponding clinker’s savings coefficient (23.4%–37.6%) and reduction of CO 2 emissions to the atmosphere during the production of Portland cement were calculated. Economic evaluations of the efficiency of using HNS in Portland cement concrete were made in comparison with different materials: commercial nanosilicas and pozzolans such as condensed silica fume, metakaolin, fly ash; metal oxides TiO 2, Al 2O 3, Fe 2O 3, ZrO 2 and multi-walled carbon nanotubes nanopowders.

This study provides data on concentrations of polycyclic aromatic hydrocarbons (PAHs) in Mediterranean mussels (Mytilus galloprovincialis), from the eastern Black Sea (Sochi, Russia). At all stations sampled, phenanthrene, pyrene, chrysene, and fluoranthene were dominant compounds. Individuals of the < 60 mm size group had significantly (p ≤ 0.05) higher concentrations of fluorene, phenanthrene, benzo[k]fluoranthene, and low-molecular-weight PAHs compared to larger individuals. The total levels of pollutants did not differ significantly between the organs, but there were variations in their qualitative composition. All indicator PAH ratios for all the specimens showed a dominance of petrogenic PAHs. The levels of toxicants in our study area were higher than those reported for Ukraine, the Bosphorus Strait, some districts of Turkey, and Bulgarian waters near the city of Varna. However, these levels proved to be lower than those off the coast of İğneada Floodplain Forests National Park and Anadolu Feneri. Thus, the coastal waters off Sochi exhibit moderate contamination by PAHs of petrogenic origin, likely coming with contaminated water discharged from ships and oil spills and accumulating near the coast due to the specific pattern of local currents.

In this work, the interaction of aluminum tris(3-chlorosulfenyl-2,4-pentanedionate) with aluminum acetylacetonate (product I), as well as cobalt(III) acetylacetonate without trapping the evolved gaseous HCl, and with addition of a binding agent (pyridine) to the system (product II and III) at a reactant ratio of 1:1 was carried out. The isolated products turned out to be soluble in toluene, chloroform, THF and were characterized using elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), X-ray phase analysis (XRD), NMR spectroscopy, scanning electron microscopy, EXAFS spectroscopy. Gel permeation chromatography data showed that the resulting 3-S-substituted acetylacetonates are polymers, with the yield of high-molecular product being highest for product I. Based on X-ray diffraction data, the polymers are amorphous in nature with particle sizes within 1.5 nm. EXAFS spectroscopy near the L359Co allowed us to calculate the actual lengths of the coordination bonds and showed that the coordination numbers of cobalt(III) in product II in the first and second coordination spheres are close to the expected model, while in the product III sample they are underestimated due to the accompanying processes of binding of the products with pyridine.