The interfacial interface between fibers and matrix plays a key role for epoxy matrix composites and short recycled randomly arranged fibers. This study used short recycled carbon fiber (RCF) as a ...filler. Plasma treatment was used for carbon fiber surface treatment. This treatment was performed using radio (RF) and microwave (MW) frequencies at the same pressure and atmosphere. Appropriate chemical modification of the fiber surfaces helps to improve the wettability of the carbon fibers and, at the same time, allows the necessary covalent bonds to form between fibers and the epoxy matrix. The effect of the plasma treatment was analyzed and confirmed by X-ray photoelectron spectroscopy, Raman microscopy, scanning electron microscopy, transmission electron microscopy and wettability measurements. Composite samples filled with recycled carbon fibers with low concentrations (1 wt%, 2.5 wt% and 5 wt%) and high concentrations (20 wt% and 30 wt%) were made from selected treated fibers. The mechanical properties (impact toughness, 3PB) were analyzed on these samples. It was found that the modulus of elasticity and bending stress increase with the increasing content of recycled carbon fibers. A more significant change in impact strength occurred in samples with low concentration.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Pure titanium and cerium oxides and their composites were prepared by the modified method of homogeneous hydrolysis with urea as the precipitating agent. The as-synthesized nanostructured oxides were ...examined by XRD, XPS, microscopic techniques (SEM, HRTEM), nitrogen physisorption, and vibrational spectroscopies (FTIR, Raman). Decontamination ability of the samples towards the toxic organophosphorus compounds was determined by two methods. The reactive adsorption of the warfare agent simulant Dimethyl methylphosphonate (DMMP) was observed by in situ FTIR spectroscopy. The degradation of the pesticide parathion methyl in a liquid medium was investigated by liquid chromatography (HPLC). Nano-ceria exhibited substantially higher degradation ability compared to nano-titania. The highest degradation efficiency was achieved with the composites with Ti:Ce 2:8 and 1:1 molar ratio. The strong interaction of Ti with Ce led to an increase of Ce3+ and formation of Ti<4+ states and changed surface area and porosity which may cause improved degradation efficacy for both DMMP and parathion methyl.
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GEOZS, IJS, NUK, OILJ, SBJE, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Layered crystal structures tend to form flat platelet-like crystallites, and nanofibers having such a structure exhibit strip-like morphology. Crystallographic plane forming the dominant flat surface ...of the nanofibers can be used for surface modification with catalytically active nanoparticles capable of anchoring to the dominant flat surface. In this study, polyvinylidene fluoride (PVDF) nanofibers exhibiting strip-like morphology and longitudinal folding were prepared using wire electrospinning, and surface modified with CeO2 nanoparticles. Experimental characterization of the CeO2/PVDF membrane using (high-resolution) scanning electron microscopy and X-ray photoelectron spectroscopy was supplemented by a force field-based molecular modeling. The modeling has shown that the dominant PVDF(100) plane is suitable for anchoring the CeO2 nanoparticles. In this respect, the PVDF(100) plane is comparable to the less exposed fluorine-oriented PVDF(010) plane, and both planes show stronger interaction with CeO2 compared to hydrogen-oriented PVDF(010) plane. Molecular modeling also revealed preferred crystallographic orientations of anchored CeO2 nanoparticles: these are the catalytically active planes (100), (110), and (111). The successful surface modification and the finding that CeO2 nanoparticles on the dominant PVDF(100) surface can preferentially exhibit these crystallographic orientations thus provides the possibility of various practical applications of the CeO2/PVDF membrane.
•Flat strip-like PVDF nanofibers were surface modified with CeO2 nanoparticles.•PVDF-CeO2 interactions were studied by molecular modeling for various (hkl) planes.•The dominant PVDF(100) surface of nanofibers is suitable for anchoring of CeO2.•Preferred orientations of CeO2 – (100), (110), (111) – on PVDF were revealed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The fabrication of inorganic transparent conductive oxide films on polymer substrates has been of increasing interest due to their potential applications in the field of flexible electronics. The ...subject of the present work is replacing the preferably-used indium tin oxide films by an aluminium zinc oxide (AZO) film in ZnO-nanorod-based devices, combining the role of the seed layer for nanorod growth with a sheet resistance lower than 100Ω/sq. The investigated AZO films with thickness up to 300nm were deposited on 150μm thick polyethylene terephthalate substrates by (i) radio-frequency magnetron sputtering from a ZnO/Al2O3 target and (ii) co-sputtering from ZnO and Al targets in an argon atmosphere. AZO films with good transparency and thickness of 160nm and sheet resistance lower than 100Ω/sq. were prepared by co-sputtering. It was found that co-sputtering leads to lower film resistivity due to better activation of Al atoms in the AZO film. ZnO nanorod growth was demonstrated on both types of film, and the co-sputtered AZO films were covered by a pure (undoped) ZnO film to improve the ZnO nanorod morphology.
•Al-doped zinc oxide (AZO) films were sputtered on polyethylene terephthalate at 100°C.•160-nm-thick AZO film with sheet resistance lower than 100Ω/sq were prepared.•Co-sputtering leads to better activation of Al atoms as donor.•Deposited films were tested as a seed layer for ZnO nanorods.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
High surface-area, mesoporous CeO2, ZrO2, and Ce-Zr composite nanoparticles were developed using the hydrothermal template-assisted synthesis method. Samples were characterized using XRD, N2 ...physisorption, TEM, XPS, and FT-IR spectroscopic methods. The CO2 adsorption ability of the obtained materials was tested under dynamic and equilibrium conditions. A high CO2 adsorption capacity in CO2/N2 flow or CO2/N2/H2O was determined for all studied adsorbents depending on their composition flow. A higher CO2 adsorption was registered for Ce-Zr composite nanomaterials due to the presence of strong O2− base sites and enriched surface oxygen species. The role of the Ce/Zr ratio is the process of the formation of highly active and selective adsorption sites is discussed. The calculated heat of adsorption revealed the processes of chemisorption and physisorption. Experimental data could be appropriately described by the Yoon–Nelson kinetic model. The composites reused in five adsorption/desorption cycles showed a high stability with a slight decrease in CO2 adsorption capacities in dry flow and in the presence of water vapor.
Surface modification of poly(ethylene naphthalate) (PEN) films by Diffuse Coplanar Surface Barrier Discharge (DCSBD) in ambient air and nitrogen at atmospheric pressure was studied at short plasma ...exposure times from 1 s up to 10 s. Chemical changes in the surface composition after the plasma treatments were studied using a high resolution XPS (X-ray Photoelectron Spectroscopy). The water contact angle was reduced from an initial value of 79° to values of 31° and 20° for the ambient air and nitrogen plasma treatments. After 3 days of storage in ambient air the contact angles were still about 50° and 40°, respectively. The polar component of surface energy was changed by the aging significantly less than the total surface energy. Despite the marked increase in the surface energy, the plasma treatment had no significant influence on the surface morphology.
The surface modification in air plasma resulted in significant reduction the OC bond formation on the treated surface. The concentration of oxygen on PEN surface was increased from an initial value of 22 at.% up to 45 at.% already after 5 s air plasma exposure, and this oxygen concentration remained constant for longer plasma treatments. A small presence of nitrogen under 1.5 at.% from the air was also found after the treatments. The nitrogen plasma modified surface composition only by implanted nitrogen up to 5 at.% when the ratio of CO and C–O was not significantly changed. But some new bonds are also expected to be formed in a very low number only.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Although the general concept of nanotechnology relies on exploitation of size-dependent properties of nanoscaled materials, the relation between the size/morphology of nanoparticles with their ...biological activity remains not well understood. Therefore, we aimed at investigating the biological activity of Se nanoparticles, one of the most promising candidates of nanomaterials for biomedicine, possessing the same crystal structure, but differing in morphology (nanorods vs. spherical particles) and aspect ratios (AR, 11.5 vs. 22.3 vs. 1.0) in human cells and BALB/c mice. Herein, we report that in case of nanorod-shaped Se nanomaterials, AR is a critical factor describing their cytotoxicity and biocompatibility. However, spherical nanoparticles (AR 1.0) do not fit this statement and exhibit markedly higher cytotoxicity than lower-AR Se nanorods. Beside of cytotoxicity, we also show that morphology and size substantially affect the uptake and intracellular fate of Se nanomaterials. In line with in vitro data, in vivo i.v. administration of Se nanomaterials revealed the highest toxicity for higher-AR nanorods followed by spherical nanoparticles and lower-AR nanorods. Moreover, we revealed that Se nanomaterials are able to alter intracellular redox homeostasis, and affect the acidic intracellular vesicles and cytoskeletal architecture in a size- and morphology-dependent manner. Although the tested nanoparticles were produced from the similar sources, their behavior differs markedly, since each type is promising for several various application scenarios, and the presented testing protocol could serve as a concept standardizing the biological relevance of the size and morphology of the various types of nanomaterials and nanoparticles.
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•Three types of Se nanomaterials are synthesized with the same crystallinity.•Se nanomaterials differ in size and morphology.•Size and morphology markedly affects uptake and intracellular fate in vitro.•Aspect ratio is a critical factor predetermining cytotoxicity of Se nanorods.•High aspect ratio of nanorods is linked with serious kidney tissue damage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aim of this study was to explore the influence of various n-propylamines (mono, di, and tri) and tert-butylamine on the properties of prepared peroxo-titanates and annealed TiO2. Detailed ...structural characterization (SEM, TEM with EDX, XRD) confirmed the 2D-foil morphology of TiO2 nanocrystals and the CHNS analysis together with XPS showed presence of carbon (under 1 wt%). The annealed TiO2 showed excellent photocatalytic activity and up to four times higher decomposition rate constant upon UV irradiation than the P25. Favourable growth of TiO2 crystals was observed especially when propylamine and tert-butylamine were used (as precursors for the peroxo-titanates). Increased photocatalytic efficiency of the highly crystalline nano-TiO2 was confirmed due to high-reactive anatase facets and the morphology composed of microsheets formed by interconnected nanocrystals. The photoinduced electron transfer was confirmed via EPR spectroscopy. This synthesis’ procedure offers a novel preparation method of highly photoactive C-doped TiO2 achieved relatively easily after annealing of lyophilized amino-peroxo-titanate.
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GEOZS, IJS, NUK, OILJ, SBJE, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background: Gas sensors are very important in several fields like gas monitoring, safety and environmental applications. In this approach, a new gas sensing concept is investigated which combines the ...powerful adsorption probability of metal oxide conductive sensors (MOS) with an optical ellipsometric readout. This concept shows promising results to solve the problems of cross sensitivity of the MOS concept. Results: Undoped tin oxide (SnOx) and iron doped tin oxide (Fe:SnOx) thin add-on films were prepared by magnetron sputtering on the top of the actual surface plasmon resonance (SPR) sensing gold layer. The films were tested for their sensitivity to several gas species in the surface plasmon resonance enhanced (SPREE) gas measurement. It was found that the undoped tin oxide (SnOx) shows higher sensitivities to propane (C3H8) then to carbon monoxide (CO). By using Fe:SnOx, this relation is inverted. This behavior was explained by a change of the amount of binding sites for CO in the layer due to this iron doping. For hydrogen (H2) no such relation was found but the sensing ability was identical for both layer materials. This observation was related to a different sensing mechanism for H2 which is driven by the diffusion into the layer instead of adsorption on the surface. Conclusion: The gas sensing selectivity can be enhanced by tuning the properties of the thin film overcoating. A relation of the binding sites in the doped and undoped SnOx films and the gas sensing abilities for CO and C3H8 was found. This could open the path for optimized gas sensing devices with different coated SPREE sensors.
The use of atmospheric plasma generated by Diffuse Coplanar Surface Barrier Discharge (DCSBD) for treatment of poly (methyl methacrylate) (PMMA) sheets is presented. The modified surfaces were ...characterized by contact angle measurements to determine the free surface energy, atomic force microscope (AFM) to investigate the changes in surface morphology, and X-ray photoelectron spectroscopy (XPS) to study the chemical composition changes after the plasma treatment. We found that increased free surface energy was related to the enhanced oxygen containing chemical groups on the polymer surface. In respect to the influence of gas composition, similar results were achieved from ambient air, nitrogen and oxygen. AFM measurements showed no effect on surface morphology by the plasma treatment. The stability of hydrophilic property was achieved over 3–5 days after plasma treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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