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The prevalence of bacterial infections presents a significant challenge in the medical field, demanding effective strategies to impede bacterial adhesion and growth on various surfaces. The conducted study investigates the efficacy of polyelectrolyte multilayerscomprising poly-(allylamine hydrochloride) (PAH) and alginate (ALG)embedded with zinc oxide (ZnO) and copper oxide (CuO) nanoparticles (NPs) to inhibit bacterial adhesion on stainless-steel surfaces. Surface characterization involved zeta potential, contact angle, and roughness assessments. The effect of NP composition, size, and morphology in conjunction with polycation or polyanion terminating multilayers was evaluated against planktonic and surface-adhered Escherichia coli (E. coli) cells. Surfaces with the positively charged PAH-terminating multilayer displayed higher water contact angles (≈ 63°) than the negatively charged ALG-terminating multilayers (≈ 45°). Multilayers containing ZnO NPs showed a significant inhibition of planktonic E. coli growth, >99%. Moreover, complete growth inhibition of surface-adhered E. coli was achieved for multilayers containing both ZnO and CuO. Due to their larger specific surface area, rod-like ZnO NPs displayed higher antibacterial activity. The samples with ALG as the terminating layer showed more substantial antibacterial properties than samples with PAH as the terminating layer. Biocompatibility tests on immortalized human keratinocyte cells revealed good compatibility with multilayers incorporating NPs. In summary, this study underscores the potential of ZnO and CuO NPs within PAH/ALG multilayers for antibacterial applications without compromising their cytocompatibility. [ABSTRACT FROM AUTHOR]

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Surface defects cause the measured tensile strength of alkali glass fibers to be significantly lower than their theoretical values. Coatings can be used to “heal” surface flaws and to modify surface properties. In the present work, the nanocoating on alkali-resistant glass (ARG) fiber rovings was carried out by self-assembled monolayers (SAMs) of octadecyltrichlorosilane (OTS). The ARG roving was dipped into OTS nanosol, which deposited the organic–inorganic SAMs of OTS on the ARG surface. The assessment of changes in the fiber surfaces was characterized by scanning electron microscopy (SEM) and fluorescence microscopy, while the chemical changes were characterized by X-ray photoelectron spectroscopy (XPS). Furthermore, the influence of nanocoating on the tensile properties of ARG and OTS-treated ARG with and without an epoxy matrix was also studied. The SEM analysis revealed the formation of nanoscale layers on the ARG surfaces and the XPS confirmed the deposition of organic–inorganic monolayers. The tensile strength of ARG rovings with and without the epoxy matrix was improved significantly. The OTS treatment almost created a superhydrophobic nanocoating on ARG, which was confirmed by the sessile drop water contact angle, and the water absorption by the ARG/epoxy composites reduced. [ABSTRACT FROM AUTHOR]

Silica, nitrogen, and nitrogen-plus-silica co-doped titania powders were synthesized via sol-gel method. The products of the synthesis were thermally treated in air and under ammonia flow. The determination of Si and/or N into the Ti O2 lattice, and the doped samples' crystal structure, was made by means of X-ray powder diffraction, whilst the occurrence of amorphous phase was obtained using the combined Rietveld- RIR method. The optical properties of the powders were obtained by diffuse reflectance spectroscopy and their energy band gaps were calculated using the differential reflectance method. The photocatalytic activity of the doped samples was assessed in gas phase under UV-light and visible-light irradiation, monitoring the degradation of an organic compound. In addition, the morphology of the samples was further on characterized by means of HRTEM. Nitrogen, silica, and co-doping shifted the anatase-to-rutile (A → R) phase transition toward higher temperatures. Silica was found to enter the anatase lattice, and nitrogen was presumed to enter the titania crystal structure as well. Nitrogen doping and Si O2/ N-co-doping shifted the light absorption toward the visible region. [ABSTRACT FROM AUTHOR]

Abstract: We have stabilized the perovskite La2/3TiO3 by adding LaFeO3 and shown that in general the stabilization mechanism for the (1− x)La2/3TiO3–x LaFeO3 mixture involves the formation of a solid solution for compositions with x ≥0.04. The crystal structure of the solid solution transforms from orthorhombic to tetragonal at x =0.2, becomes cubic in the range 0.3< x <0.8, and transforms again into orthorhombic (typical for pure LaFeO3) for values greater than 0.8. Detailed impedance-spectroscopy measurements for various compositions and conditions showed that the limiting step in the conduction mechanism was conduction across the grain boundaries. In the concentration range 0.04< x <0.25 the room temperature conductivity increases up to 0.0017Scm−1, after which it decreases again. Part of the initial increase is probably due to the formation of free electrons in accordance with (FeTi)′→(FeTi) x + n′. Other defect-formation mechanisms are also discussed, but are ruled out for a variety of reasons. Another interesting phenomenon that also affected the average conductivity was identified, i.e., the variation of the average particle size with composition. [Copyright &y& Elsevier]

In the process of protection and consolidation of valuable materials, the efficiency is the crucial property that needs to be considered. TiO2/ZnAl layered double hydroxide (LDH) coating and silicate- and carbonate-based consolidants were synthesized and proposed to be used for protection and consolidation of four porous mineral substrates: brick, stone, render and mortar. The photocatalytic efficiency of TiO2/ZnAl LDH coating, as well as consolidation efficiency of two consolidants, both applied on model substrates, were studied. The photocatalytic coating showed significant activity and performed well after the durability tests involving rinsing and freezing/thawing procedures. After treatment with both consolidants, a serious enhancement of consolidation of the used substrates was found. On the other hand, the application of TiO2/ZnAl LDH, as well as consolidants, caused negligible changes in the water vapour permeability values and in appearance of the porous mineral substrates, indicating a high level of compatibility. [ABSTRACT FROM AUTHOR]

Abstract: The parameters which influence the removal of different zinc (Zn) species: Zn2+, Zn(II)–EDTA and Zn(II)–citrate from aqueous solutions by nanoparticles of zero-valent iron (nZVI) were investigated at environmental relevant pH values. Untreated, surface modified and silica-fume supported nZVI were applied at different iron loads and contact times to Zn solutions, which were buffered to pH5.3, 6.0 and 7.0. The results revealed that pH, the type of nZVI, the iron load, the contact time, and the Zn species all had a significant influence on the efficiency of removal. Zn2+, Zn(II)–EDTA and Zn(II)–citrate were the most effectively removed from aqueous solutions by untreated nZVI. Zn2+ removal was governed mainly by adsorption onto precipitated iron oxides. Complete removal of Zn2+ and Zn(II)–citrate was obtained at all pH values investigated. The removal of strong Zn(II)–EDTA complex was successful only at acidic pH, which favored degradation of Zn(II)–EDTA. Consequently, the released Zn2+ was completely removed from the solution by adsorption onto iron oxides. [Copyright &y& Elsevier]

Abstract: Surfactant-assisted anatase mesoporous TiO2 transparent films, along with P25 translucent films were successfully synthesized and deposited by dip-coating technique. Prepared films were characterized by UV–Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and N2 adsorption–desorption measurements. The hydrophilicity of films was assessed by water contact angle technique. The results revealed that the surfactant-assisted sol–gel films were homogeneous, crack-free, contained anatase phase only with small grain size, and showed an increase in BET surface area and wide range of pore size distribution compared to non-surfactant treated sample. The optical properties and photocatalytic activity of the films for an azo dye, Plasmocorinth B (PB) degradation were analyzed with UV–Vis spectrometer. The photocatalytic activity of the synthesized anatase TiO2 films having high optical quality is comparable to the activity of reference commercial powder P25 films. Relevant results are presented and discussed as a function of the structure and morphology of coatings, which control enables a direct tailoring of the functional response. The high porosity, uniformity, transparency, reliability, photocatalytic activity, good adhesion with the substrate and the excellent performance under cycling operation displayed by surfactant-assisted anatase TiO2 coatings make it a good candidate to be considered in new emerging engineering applications. [Copyright &y& Elsevier]

Abstract: A series of TiO2–SiO2 mixtures – having the following stoichiometry Ti1−x Si x O2, with x =0, 0.1, 0.3 and 0.5 atoms per formula unit – were prepared by using precursor oxides and fired at three temperatures (900, 1000 and 1200°C). The modifications in the structure and, consequently, on the photocatalytic activity, induced by the addition of SiO2 into the TiO2 powder, were thoroughly investigated by using various analytical techniques: X-ray powder diffraction, electron microscopy (FE-SEM and TEM), XPS, FT-IR, DRS and BET analysis. The results underlined as essentially no solid solution occurs between the two crystalline end-members. Nevertheless, silica addition caused a retarding effect on anatase-to-rutile phase transformation and on the crystallite growth. The photocatalytic activity of the powders was assessed in gas phase and the results were explained by taking into account the anatase and rutile relative amounts in the samples, their crystallite size, the surface hydroxyl groups adsorbed on the photocatalysts and the surface area of the mixtures. [Copyright &y& Elsevier]

The application of TiO2 photocatalysis in various environmental fields has been extensively studied in the last decades due to its ability to induce the degradation of adsorbed organic pollutants. In the present work, TiO2 powders doped and co-doped with sulfur and nitrogen and modified with platinum were prepared by particulate sol-gel synthesis. PXRD measurements revealed that the replacement of HCl with H2SO4 during synthesis reduced the size of the crystallites from ~ 30 nm to ~20 nm, increasing the surface area from ~44 m²/g to ~80 m²/g. This is consistent with the photocatalytic activity of the samples and the measured photocurrent behavior of the photocatalysts. The results showed that the properties of the powders (i.e., surface area, crystallite size, photocurrent behavior) depend strongly not only on the type but also on the amount of acid and dopants used in the synthesis. Doping, co-doping and modification of TiO2 samples with nitrogen, sulfur and platinum increased their photocatalytic activity up to 6 times. [ABSTRACT FROM AUTHOR]

The effects of two metallocene ethylene-propylene-based elastomers (m-EPR1 and m-EPR2) differing in molecular mass and viscosity on mechanical, rheological and interfacial properties were compared. The m-EPR elastomers were added to iPP in 2.5, 5, 10, 15, and 20 vol.%. Torque values, elongation at break and impact strength measured of the iPP/m-EPR1 blends were higher than the iPP/m-EPR2 blends due to higher molten viscosity of m-EPR1 than m-EPR2 copolymer. Slight differences in Young moduli as well as in tensile strength at yield and at break might indicate that tensile properties of iPP/m-EPR blends were not significantly affected by difference in viscosity or molecular mass, miscibility and spherulite size. Optimization diagrams indicated the metallocene m-EPR copolymers are efficient impact modifiers for polypropylene and showed good balancing of mechanical properties in iPP/m-EPR blends. [ABSTRACT FROM AUTHOR]

Titania nanoparticles were synthesized by employing the hydrothermal method and using TiOSO4 as a titanium source. By varying pH between 0.5 and 1.0 and adding isopropanol to the hydrothermal reaction mixture, different mixtures of anatase, rutile, and brookite were obtained. The samples were also doped with nitrogen at different N concentrations using, respectively, urea, ammonium nitrate, and tripropylamine as nitrogen sources. The samples were characterized by X-ray powder diffraction, field emission scanning electron microscopy, infrared spectroscopy, UV-Vis diffuse reflectance spectroscopy and according to their specific surface area. Additionally, their photocatalytic activity was measured in a gas-solid reactor system. The results show that low pH favours rutile formation, whereas a higher pH yields mixed phase titania polymorphs. Isopropanol addition also favours rutile formation, and boosted the photocatalytic activity of the resulted particles. Contrary to most data in the literature, rutile turned out to be the more active phase in the present investigation. Nitrogen doping, on the other hand, did not contribute to higher photocatalytic activity, but was rather detrimental to it. [ABSTRACT FROM AUTHOR]