| 1. |
- Khort, Alexander, et al.
(författare)
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Corrosion and transformation of solution combustion synthesized Co, Ni and CoNi nanoparticles in synthetic freshwater with and without natural organic matter
- 2021
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Ingår i: Scientific Reports. - : Nature Research. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Pure metallic Co, Ni, and their bimetallic compositions of Co3Ni, CoNi, and CoNi3 nanomaterials were prepared by solution combustion synthesis. Microstructure, phase composition, and crystalline structure of these nanoparticles (NPs) were characterized along with studies of their corrosion and dissolution properties in synthetic freshwater with and without natural organic matter (NOM). The nanomaterials consisted of aggregates of fine NPs (3–30 nm) of almost pure metallic and bimetallic crystal phases with a thin surface oxide covered by a thin carbon shell. The nanomaterials were characterized by BET surface areas ranging from ~ 1 to 8 m2/g for the Ni and Co NPs, to 22.93 m2/g, 14.86 m2/g, and 10.53 m2/g for the Co3Ni, CoNi, CoNi3 NPs, respectively. More Co and Ni were released from the bimetallic NPs compared with the pure metals although their corrosion current densities were lower. In contrast to findings for the pure metal NPs, the presence of NOM increased the release of Co and Ni from the bimetallic NPs in freshwater compared to freshwater only even though its presence reduced the corrosion rate (current density). It was shown that the properties of the bimetallic nanomaterials were influenced by multiple factors such as their composition, including carbon shell, type of surface oxides, and the entropy of mixing. © 2021, The Author(s).
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| 2. |
- Bautin, V. A., et al.
(författare)
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Selective laser melting of low-alloyed titanium based alloy with a large solidification range
- 2024
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Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- In this work, thermodynamic calculations for α + β Type Ti–Fe–Cu–Sn alloy were carried out by the Thermo-Calc software. Powders from this alloy were obtained by plasma sputtering and used for subsequent 3D printing of experimental samples. The effect of various selective laser melting (SLM) parameters on porosity and hot cracking susceptibility as well as the electrochemical characteristics of the alloy have been studied. The optimal technological regime for the manufacture of samples by the SLM method was determined. It has been established that to obtain relatively dense samples without cracks, regimes with volumetric energy density Ev = 250–300 J/mm3 are required. It has been established that a change in the electrochemical behavior of the Ti94Fe1Cu1Sn4 alloy is related to the formation of a nonequilibrium Ti2Cu phase. Based on the findings we recomended directions for further research.
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| 3. |
- Chang, Tingru, et al.
(författare)
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Effects of interactions between natural organic matter and aquatic organism degradation products on the transformation and dissolution of cobalt and nickel-based nanoparticles in synthetic freshwater
- 2023
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 445, s. 130586-130586
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Tidskriftsartikel (refereegranskat)abstract
- Expanding applications and production of engineered nanoparticles lead to an increased risk for their environmental dispersion. Systematic knowledge of surface transformation and dissolution of nanoparticles is essential for risk assessment and regulation establishment. Such aspects of Co- and Ni-based nanoparticles including metals, oxides, and solution combustion synthesized metal nanoparticles (metal cores with carbon shells) were investigated upon environmental interaction with organic matter, simulated by natural organic matter (NOM) and degradation products from zooplankton and algae (eco-corona biomolecules, EC) in freshwater (FW). The presence of NOM and EC in FW results in negative surface charges of the nanoparticles reduces the extent of nanoparticles agglomeration, and increases concentration, mainly due to the surface adsorption of carboxylate groups of the organic matter. The dissolution of the Co-based nanoparticles was for all conditions (FW, FW with NOM or EC) higher than the Ni-based, except for Co3O4 being nearly non-soluble. The surface transformation and dissolution of nanoparticles are highly exposure and time-dependent, and surface- and environment specific. Therefore, no general correlation was observed between dissolution and, particle types, surface conditions, or EC/NOM adsorption. This underlines the importance of thorough investigations of nanoparticles adsorption/desorption, degradation, and exposure scenarios for developing regulatory relevant protocols and guidelines.
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| 4. |
- Haiduk, Yulyan S., et al.
(författare)
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Structure and gas sensitivity of WO3–In2O3 and WO3–Co3O4 oxide compositions
- 2019
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Ingår i: Modern Electronic Materials. - : Pensoft Publishers. - 2452-2449 .- 2452-1779. ; 5:3, s. 115-125
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Tidskriftsartikel (refereegranskat)abstract
- Using oxide compositions is a promising method of increasing the sensitivity and selectivity of semiconductor gas sensors on the basis of SnO2, In2O3, WO3 and other oxides. We have studied nanocrystalline tungsten oxide (WO3), indium oxide (In2O3), cobalt oxide (Co3O4) and mixed oxide compositions with different WO3/In2O3 and WO3/Co3O4 ratios synthesized using the sol-gel method after xerogel annealing at 400–600 °C. The morphology, phase composition and structure of the materials have been studied using X-ray diffraction, infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. We showed that stable structures can be produced in WO3–In2O3 and WO3–Со3O4 nanoheterogeneous compositions. The growth of grain size in WO3 and In2O3, WO3 and Co3O4 during heat treatment of mixed compositions occurs slower than in simple oxides. An increase in the gas sensitivity of the compositions in comparison with simple oxides can be accounted for by smaller grain sizes and hence larger specific surface area, as well as by the dependence of grain surface state on material composition. Both compositions exhibit the greatest nitrogen dioxide response at 130–150 °C and the greatest carbon oxide response at above 230 °C. We have produced low-power nitrogen dioxide sensors with a sensitivity of << 1 ppm and power consumption of ≤ 85 mW.
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| 5. |
- Haiduk, Yulyan, et al.
(författare)
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WO3–graphene–Cu nanocomposites for CO, NO2 and acetone gas sensors
- 2022
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Ingår i: Nano-Structures & Nano-Objects. - : Elsevier BV. - 2352-507X. ; 29, s. 100824-
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Tidskriftsartikel (refereegranskat)abstract
- The control of indoor air quality and the detection of toxic gases and volatile organic compounds are important tasks for improving life and work conditions, and are highly demanded in a variety of industrial, agricultural and environmental applications. This requires the development of special gas sensing materials with a high sensing response to a variety of gases of a different chemical nature. Herein we report a study on the synthesis, characterization and investigation of the gas sensing properties of WO3 -graphene–Cu composite nanomaterials. The nanomaterials have a closely interconnected defective structure with developed surfaces and are characterized by an enhanced sensing response to CO, NO2 and acetone. The composite nanomaterials with WO3 crystallite sizes of 13–17 nm were synthesized by a modified sol–gel method, where pre-synthesized graphene@Cu nanopowder, obtained by the solution combustion method, was added into an H2WO4 gel before the xerogel formation stage. The graphene@Cu flakes played the role of the centers of WO3 crystallite nucleation, leading to the formation of mutually interconnected crystalline structures. The graphene@Cu composite tends to accumulate on the tungsten oxide surfaces, causing the formation of structural defects, influencing the surface energy state and concentration of free electrons. The concentration of defects decreases with the increase of graphene@Cu from 1 to 4 wt%, which also affects the gas sensing properties of the WO3-graphene@Cu composites. The highest sensing response to CO and acetone of 19.7 and 21.4, respectively, were detected for the composite with 1 wt% of graphene@Cu. The composite with 2 wt.% of graphene@Cu additive showed the highest sensing response to NO2.
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| 6. |
- Kelpsiene, Egle, et al.
(författare)
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The effect of natural biomolecules on yttrium oxide nanoparticles from a Daphnia magna survival rate perspective
- 2023
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Ingår i: Nanotoxicology. - : Taylor and Francis Ltd.. - 1743-5390 .- 1743-5404. ; 17:4, s. 385-399
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Tidskriftsartikel (refereegranskat)abstract
- The attention to rare earth oxide nanoparticles (NPs), including yttrium oxide (Y2O3), has increased in many fields due to their unique structural characteristics and functional properties. The aim of our study was to investigate the mechanisms by which bio-corona formation on Y2O3 NPs affects their environmental fate and toxicity. The Y2O3 NPs induced toxicity to freshwater filter feeder Daphnia magna at particle concentrations of 1 and 10 mg/L, regardless of particle size. Interactions between naturally excreted biomolecules (e.g. protein, lipids, and polysaccharides) derived from D. magna, and the Y2O3 NPs (30–45 nm) resulted in the formation of an eco-corona, which reduced their toxic effects toward D. magna at a particle concentration of 10 mg/L. No effects were observed at lower concentrations or for the other particle sizes investigated. Copper-zinc (Cu-Zn) superoxide dismutase, apolipophorins, and vitellogenin-1 proteins proved to be the most prominent proteins of the adsorbed corona, and possibly a reason for the reduced toxicity of the 30–45 nm Y2O3 NPs toward D. magna.
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| 7. |
- Khaliullin, S. M., et al.
(författare)
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Effect of the residual water content in gels on solution combustion synthesis temperature
- 2020
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Ingår i: Journal of Sol-Gel Science and Technology. - : Springer. - 0928-0707 .- 1573-4846. ; 93:2, s. 251-261
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Tidskriftsartikel (refereegranskat)abstract
- The composition of gels and xerogels, as well as their transformation during heating and dehydration, determine the thermochemistry of solution combustion synthesis reactions. An improved descriptive thermodynamic model of combustion processes was formulated on the basis of the investigated formation of complex compounds of metal ions with organic fuel (glycine, citric acid, urea, and PVA) in nitrate solutions. The intensity of SCS reactions was found to depend on the strength of Ni2+–ligand complexes. The effect of heat loss during combustion on the ΔTmax value was analyzed for the model system Ni(NO3)2·nH2O–Fuel–H2O. It was found the heat loss occurs due to the presence of various amounts of structurally-bound water in gels and xerogels before the combustion. [Figure not available: see fulltext.]
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| 8. |
- Khort, Aliaksandr, et al.
(författare)
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CO oxidation and organic dyes degradation over graphene–Cu and graphene–CuNi catalysts obtained by solution combustion synthesis
- 2020
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Graphene and its analogs in combination with metal nanopowders are among the most promising catalysts for various industry valuable processes. The newly obtained solution combustion synthesized graphene–Cu and graphene–CuNi nanocomposites were examined in heterogeneous catalysis of thermal activated CO oxidation and photoactivated degradation of acid telon blue and direct blue dyes. The nanocomposites are characterized by a closely connected solution combustion synthesized graphene-metal structure with a number of graphene layers from 1 to 3 and fine metal grains sizes of 31 nm (Cu) and 14 nm (CuNi). The experimental data showed the obtained graphene-metal nanocomposites are among the most effective catalysts for CO oxidation with a temperature of 100% conversion of 150 °C and 200 °C for Cu and CuNi containing catalysts, respectively. At the same time, both nanopowders were found inactive for dyes degradation.
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| 9. |
- Khort, Aliaksandr, et al.
(författare)
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Effect of reductant type on phase composition and ferroelectric behavior of combustion-synthesized BaTiO3 and Bi4Ti3O 12
- 2014
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Ingår i: International Journal of Self-Propagating High-Temperature Synthesis. - : Allerton Press Incorporation. - 1061-3862. ; 23:2, s. 106-111
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Tidskriftsartikel (refereegranskat)abstract
- Finely dispersed BaTiO3 and Bi4Ti3O 12 powders were prepared by solution-combustion synthesis using glycine, carbamide, and glycerol as reducing agents. The use of glycine as a reducing agent was found to yield single-phase BaTiO3 and Bi 4Ti3O12 without additional heat treatment. Explored was the influence of reductant type and process parameters on the phase composition, crystal structure, and dielectric properties of combustion-synthesized barium and bismuth titanates.
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| 10. |
- Khort, Aliaksandr, Dr, 1987-, et al.
(författare)
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Influence of natural organic matter on the transformation of metal and metal oxide nanoparticles and their ecotoxic potency in vitro
- 2022
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Ingår i: Nanoimpact. - : Elsevier BV. - 2452-0748. ; 25
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Tidskriftsartikel (refereegranskat)abstract
- Increased use and production of engineered nanoparticles (NPs) lead to an elevated risk of their diffuse dispersion into the aquatic environment and increased concern on unknown effects induced by their release into the aquatic ecosystem. An improved understanding of the environmental transformation processes of NPs of various surface characteristics is hence imperative for risk assessment and management. This study presents results on effects of natural organic matter (NOM) on the environmental transformation and dissolution of metal and metal oxide NPs of different surface and solubility properties in synthetic freshwater (FW) with and without NOM. Adsorption of NOM was evident on most of the studied NPs, except Sb and Sb2O3, which resulted in the formation of negatively charged colloids of higher stability and smaller size distribution compared with the same NPs in FW only. The dissolution rate of the NPs in the presence of NOM correlated with the strength of interactions between the carboxylate group of NOM and the particle surface, and resulted in either no (Mn, Sb, ZnO NPs), increased (Co, Sn NPs) and decreased (Ni, NiO, Sb2O3, Y2O3 NPs) levels of dissolution. One type of metal NP from each group (Mn, Ni, Sn) were investigated to assess whether observed differences in adsorption of NOM and dissolution would influence their ecotoxic potency. The results showed Mn, Ni, and Sn NPs to generate intracellular reactive oxygen species (ROS) in a time and dose-dependent manner. The extent of ROS generation in FW was similar for both Mn and Ni NPs but higher for Sn NPs. These findings are possibly related to interactions and infiltration of the NPs with the cells, which lead to redox imbalances which could induce oxidative stress and cell damage. At the same time, the presence of NOM generally reduced the intracellular ROS generation by 20-40% for the investigated NPs and also reduced cytotoxicity of Sn NPs, which can be attributed to the stronger interaction of carboxylate groups of NOM with the surface of the NPs.
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