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The removal of pollutants, including heavy metals, from the aquatic environment is an urgent problem worldwide. Actively developing nanotechnology areas is becoming increasingly important for solving problems in the field of the remediation of aquatic ecosystems. In particular, methods for removing pollutants using nanoparticles (NPs) are proposed, which raises the question of the effect of a combination of NPs and heavy metals on living organisms. In this work, we investigated the role of CuO-NPs in changing the toxicity of Cd and Pb salts, as well as the bioaccumulation of these elements in a culture of the microalga Desmodesmus communis . It was found that CuO-NPs at concentrations of 10, 100, and 1000 µg L -1 had no effect on the viability of microalgae cells. On the 14th day of the experiment, Cd at a concentration of 1 mg L -1 reduced the viability index by 30% and, when combined with CuO-NPs, by 25%, i.e., CuO-NPs slightly reduced the toxic effect of Cd. At the same time, in this experiment, when CuO-NPs and Cd were used together, the level of oxidative stress increased, including on the first day in mixtures with 1 mg L -1 Cd. Under the influence of Pb, the cell viability index decreased by 70% by the end of the experiment, regardless of the metal concentration. The presence of CuO-NPs slightly reduced the toxicity of Pb in terms of viability and reactive oxygen species (ROS). At the same time, unlike Cd, Pb without NPs caused ROS production on the first day, whereas the addition of CuO-NPs completely detoxified Pb at the beginning and had a dose-dependent effect on mixtures at the end of the experiment. Also, the introduction of CuO-NPs slightly reduced the negative effect of Pb on pigment synthesis. As a molecular mechanism of the observed effects, we prioritized the provocation of oxidative stress by nanoparticles and related gene expression and biochemical reactions of algae cells. Analysis of the effect of CuO-NPs on the Cd and Pb content in microalgae cells showed increased accumulation of heavy metals. Thus, when algae were cultured in an environment with Cd and CuO-NPs, the Cd content per cell increased 4.2 times compared to the variant where cells were cultured only with Cd. In the case of Pb, the increase in its content per one cell increased 6.2 times when microalgae were cultured in an environment containing CuO-NPs. Thus, we found that CuO-NPs reduce the toxic effects of Cd and Pb, as well as significantly enhance the bioaccumulation of these toxic elements in the cells of D. communis microalgae. The results obtained can form the basis of technology for the nanobioremediation of aquatic ecosystems from heavy metals using microalgae., Competing Interests: The authors declare no conflicts of interest.

In this work, we present an analysis of the antibacterial activity of TiS 3 nanostructures in water and 0.9% NaCl solution suspensions. TiS 3 nanoribbons 1-10 µm long, 100-300 nm wide, and less than 100 nm thick were produced by the direct reaction of pure titanium powder with elemental sulphur in a quartz tube sealed under vacuum. For the toxicity test of a bioluminescent strain of E. coli we used concentrations from 1 to 0.0001 g L -1 and also studied fresh suspensions and suspensions left for 24 h. The strongest toxic effect was observed in freshly prepared water solutions where the luminescence of bacteria decreased by more than 75%. When saline solution was substituted for water or when the solutions were stored for 24 h it resulted in a considerable decrease in the TiS 3 antibacterial effect. The toxicity of TiS 3 in water exceeded the toxicity of the reference TiO 2 nanoparticles, though when saline solution was used instead of water the opposite results were observed. In addition, we did not find a relationship between the antibacterial activity of water suspensions of nanoribbons and the stability of their colloidal systems, which indicates an insignificant contribution to the toxicity of aggregation processes. In 0.9% NaCl solution suspensions, toxicity increased in proportion to the increase in the zeta potential. We suppose that the noted specificity of toxicity is associated with the emission of hydrogen sulphide molecules from the surface of nanoribbons, which, depending on the concentration, can either decrease or increase oxidative stress, which is considered the key mechanism of nanomaterial cytotoxicity. However, the exact underlying mechanisms need further investigation. Thus, we have shown an important role of the dispersion medium and the period of storage in the antibacterial activity of TiS 3 nanoribbons. Our results could be used in nanotoxicological studies of other two-dimensional nanomaterials, and for the development of novel antibacterial substances and other biomedical applications of this two-dimensional material.

Due to their chemical, mechanical, and optical properties, 2D ultrathin nanomaterials have significant potential in biomedicine. However, the cytotoxicity of such materials, including their mutual increase or decrease, is still not well understood. We studied the effects that graphene oxide (GO) nanolayers (with dimensions 0.1-3 μm and average individual flake thickness less than 1 nm) and ZrS 3 nanoribbons (length more than 10 μm, width 0.4-3 μm, and thickness 50-120 nm) have on the viability, cell cycle, and cell death of HCT116 colon carcinoma cells. We found that ZrS 3 exhibited strong cytotoxicity by causing apoptotic cell death, which was in contrast to GO. When adding GO to ZrS 3 , ZrS 3 was significantly less toxic, which may be because GO inhibits the effects of cytotoxic hydrogen sulfide produced by ZrS 3 . Thus, using zirconium trisulfide nanoribbons as an example, we have demonstrated the ability of graphene oxide to reduce the cytotoxicity of another nanomaterial, which may be of practical importance in biomedicine, including the development of biocompatible nanocoatings for scaffolds, theranostic nanostructures, and others.

This paper describes an experimental study of the relationships between thermal diffusivity and mechanical characteristics including Brinell hardness, microhardness, and Young's modulus of common pine ( Pinus sylvestris L.), pedunculate oak ( Quercus robur L.), and small-leaf lime ( Tilia cordata Mill.) wood. A dependence of Brinell hardness and thermal diffusivity tensor components upon humidity for common pine wood is found. The results of the measurement of Brinell hardness, microhardness, Young's modulus, and main components of thermal diffusivity tensor for three perpendicular cuts are found to be correlated. It is shown that the mechanical properties correlate better with the ratio of longitude to transversal thermal diffusivity coefficients than with the respective individual absolute values. The mechanical characteristics with the highest correlation with the abovementioned ratio are found to be the ratio of Young's moduli in longitude and transversal directions. Our technique allows a comparative express assessment of wood mechanical properties by means of a contactless non-destructive measurement of its thermal properties using dynamic thermal imaging instead of laborious and material-consuming destructive mechanical tests.

ZSM-5-containing catalytic additives are widely used in oil refineries to boost light olefin production and improve gasoline octanes in the Fluid Catalytic Cracking (FCC) process. Under the hydrothermal conditions present in the FCC regenerator (typically >700 °C and >8% steam), FCC catalysts and additives are subject to deactivation. Zeolites (e.g., Rare Earth USY in the base catalyst and ZSM-5 in Olefins boosting additives) are prone to dealumination and partial structural collapse, thereby losing activity, micropore surface area, and undergoing changes in selectivity. Fresh catalyst and additives are added at appropriate respective levels to the FCC unit on a daily basis to maintain overall targeted steady-state (equilibrated) activity and selectivity. To mimic this process under accelerated laboratory conditions, a commercial P/ZSM-5 additive was hydrothermally equilibrated via a steaming process at two temperatures: 788 °C and 815 °C to simulate moderate and more severe equilibration industrial conditions, respectively. n -Dodecane was used as probe molecule and feed for micro-activity cracking testing at 560 °C to determine the activity and product selectivity of fresh and equilibrated P-doped ZSM-5 additives. The fresh/calcined P/ZSM-5 additive was very active in C 12 cracking while steaming limited its activity, i.e., at catalyst-to-feed (C/F) ratio of 1, about 70% and 30% conversion was obtained with the fresh and steamed additives, respectively. A greater activity drop was observed upon increasing the hydrothermal deactivation severity due to gradual decrease of total acidity and microporosity of the additives. However, this change in severity did not result in any selectivity changes for the LPG (liquefied petroleum gas) olefins as the nature (Brønsted-to-Lewis ratio) of the acid/active sites was not significantly altered upon steaming. Steam deactivation of ZSM-5 had also no significant effect on aromatics formation which was enhanced at higher conversion levels. Coke remained low with both fresh and steam-deactivated P/ZSM-5 additives., Competing Interests: The authors declare no conflict of interest.