Antimicrobial action and chemical and physical properties of CuO-doped engineered cementitious composites.

CuO nanoparticles (NPs) were added to cement matrices in quantities of 0.25, 0.50 and 1.00 wt% to inhibit the growth of Gram-positive (Bacillus cereus, Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa, Escherichia coli) bacteria. It was shown that CuO NPs, in all tested concentrations, improved the antibacterial properties of the cement matrix. Nevertheless, the best mechanical, structural and durability properties were obtained for cement composites doped with CuO NPs at 0.25 wt%. Larger amounts of NPs caused a decrease in all parameters relative to the reference mortar, which may be the result of a slight change in the porosity of the composite microstructure. For 0.50 wt% CuO NPs, a slight increase in the volume of micropores in the cement matrix was observed, and an increased number of larger pores was confirmed by non-invasive computed tomography (CT). The reduction in the mechanical parameters of composites with 0.50 and 1.00 wt% CuO NPs may also be due to the slower hydration of the cement binder, as confirmed by changes in the heat of hydration for these configurations, or agglomeration of NPs, especially for the 1.00 wt% concentration, which was manifested in a decrease in the plasticity of the mortars.

Surface modification of magnetic nanoparticles by bacteriophages and ionic liquids precursors.

Magnetic nanoparticles (MNPs) have recently been a point of interest for many researchers due to their properties. However, the studies on the influence of bacteriophages on the synthesis of MNPs seem to be lacking. Furthermore, bacteriophage-modified MNPs have not been combined with n-alkyl quaternary ammonium ionic liquid precursors (QAS). In this study, the aim was to assess the influence of two distinctly different bacteriophages (Escherichia phage P1 and Pseudomonas phage Φ6) on MNPs synthesis in the presence or absence of QAS. Synthesized MNPs have been characterized with X-ray diffraction (XRD) and Mössbauer spectroscopy in terms of changes in the crystallographic structure; scanning electron microscopy (SEM) for changes in the morphology; and ζ-potential. Moreover, the sorption parameters and the loss of viability of bacteria that interacted with MNPs have been determined. The sorption of bacteria differs significantly among the tested samples. Furthermore, the viability of the bacteria adsorbed on MNPs varies in the presence of QAS, depending on the length of the n-alkyl chain. The study has revealed that MNPs can be bound with bacteriophages. Mössbauer spectroscopy has also revealed the probable influence of bacteriophages on the formation of crystals. However, these phenomena require further studies.

Remarkable Structural Modifications of Tialite Solid Solutions Obtained by Different Methods.

The structural changes occurring in tialite due to the formation of magnesium-titanate-aluminum-titanate solid solutions were determined. For this purpose, a DFT simulation of the structural changes was performed. The simulation proposed a number of possible atomic substitutions occurring in the elementary cells of the tialite, along with calculations of the lattice parameter changes in this material. Next, the actual changes occurring in the structure of the tialite due to the formation of solid solutions, obtained in different ways, were investigated. After comparing the obtained results, it was possible to confirm the mechanism of the formation of tialite solid solutions, through which one magnesium atom and one titanium atom substituted two aluminum atoms simultaneously. The results of this experimental work were confirmed by theoretical calculations (the differences in the values of the lattice parameters, measured in the experiment and calculated in the simulation, were less than 0.5%), through which changes in the lattice parameters with Mg and Ti substitution were observed.

Effect of Expanded Graphite on the Reaction Sintering of Boron Carbide.

This paper presents novel results of research focused on reaction sintering of a mixture of expanded graphite and amorphous boron. It has been shown that as a result of combining the synthesis from the elements with sintering under pressure, dense boron carbide polycrystals (95% TD) can be obtained in which stable structures dominate, i.e., boron carbides of stoichiometry B13C2 and B4C. Sintering was carried out on boron excess systems, and reaction mixtures with the following mass ratios (B:C = 5:1; 10:1; and 15:1) were used. Boron excess systems were used due to the presence of additional carbon during sintering since the matrix, reactor lining, and heating elements were made of graphite. 1850 °C was considered to be the optimum reaction sintering temperature for all of the systems tested. This shows that a reduction in the sintering temperature of 200-300 °C was observed with respect to traditional sintering techniques. Micro-cracks are present in the sinters, the presence of which is most likely due to the difficulty in removing the gaseous products which accompany the boron carbide synthesis reaction. The elimination of these defects of sintering requires further research.

Organobentonites Modified with Poly(Acrylic Acid) and Its Sodium Salt for Foundry Applications.

The article aims to verify the possibility of obtaining an organic-inorganic material acting as both a binder and a lustrous carbon carrier in bentonite-bonded molding sands. Due to the wide industrial application, organoclays can be considered as innovative materials supporting the foundry technology in meeting environmental requirements. In this study, the organic modification of montmorillonite in calcium bentonite (SN) was performed by poly(acrylic acid) (PAA) and its sodium salt (PAA/Na). Additionally, for the purpose of comparison, the sodium-activated bentonite/poly(acrylic acid) (SN-Na/PAA) composites were also prepared. The collective analysis of the research results used in the assessment of the mineral/polymer interaction mechanism indicates surface adsorption combined with the intercalation of PAA monolayer into the mineral interlayer spaces. Materials were characterized by the combination of Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) methods. Based on the XRD analysis, the influence of PAA/Na on the aluminosilicate layered structure was found to be destructive, which may adversely affect the binding properties of SN/PAA/Na composites considered as a potential group of new foundry binders. The SN/PAA and SN-Na/PPA composites (with appropriate polymer content) can act as a binding agent in the synthetic molding sand technology, despite coating the bentonite particles with polymer molecules. The risk of losing the mineral's binding capacity is reduced by the good binding properties of pol(acrylic acid) itself. The article is the first stage (preceding the thermal analysis and the strength tests of molding sands with the prepared organobentonites) in determining the possibility of obtaining a new full-value foundry binder in molding sands with bentonite.

Effects of Process Parameters on Structure and Properties of Melt-Blown Poly(Lactic Acid) Nonwovens for Skin Regeneration.

Skin regeneration requires a three-dimensional (3D) scaffold for cell adhesion, growth and proliferation. A type of the scaffold offering a 3D structure is a nonwoven material produced via a melt-blown technique. Process parameters of this technique can be adapted to improve the cellular response. Polylactic acid (PLA) was used to produce a nonwoven scaffold by a melt-blown technique. The key process parameters, i.e., the head and air temperature, were changed in the range from 180-270 °C to obtain eight different materials (MB1-MB8). The relationships between the process parameters, morphology, porosity, thermal properties and the cellular response were explored in this study. The mean fiber diameters ranged from 3 to 120 µm. The average material roughness values were between 47 and 160 µm, whereas the pore diameters ranged from 5 to 400 µm. The calorimetry thermograms revealed a correlation between the temperature parameters and crystallization. The response of keratinocytes and macrophages exhibited a higher cell viability on thicker fibers. The cell-scaffold interaction was observed via SEM after 7 days. This result proved that the features of melt-blown nonwoven scaffolds depended on the processing parameters, such as head temperature and air temperature. Thanks to examinations, the most suitable scaffolds for skin tissue regeneration were selected.

Superparamagnetic Iron Oxide Nanoparticles Modified with Silica Layers as Potential Agents for Lung Cancer Treatment.

Superparamagnetic iron oxide nanoparticles (SPIONs) are promising drug delivery carriers and hyperthermia agents for the treatment of cancer. However, to ensure their safety in vivo, SPIONs must be modified in order to prevent unwanted iron release. Thus, SPIONs were coated with silica layers of different morphologies: non-porous (@SiO2), mesoporous (@mSiO2) or with a combination of non-porous and mesoporous layers (@SiO2@mSiO2) deposited via a sol-gel method. The presence of SiO2 drastically changed the surface properties of the nanoparticles. The zeta potential changed from 19.6 ± 0.8 mV for SPIONs to -26.1 ± 0.1 mV for SPION@mSiO2. The Brunauer-Emmett-Teller (BET) surface area increased from 7.54 ± 0.02 m2/g for SPIONs to 101.3 ± 2.8 m2/g for SPION@mSiO2. All types of coatings significantly decreased iron release (at least 10 fold as compared to unmodified SPIONs). SPIONs and SPION@mSiO2 were tested in vitro in contact with human lung epithelial cells (A549 and BEAS-2B). Both nanoparticle types were cytocompatible, although some delay in proliferation was observed for BEAS-2B cells as compared to A549 cells, which was correlated with increased cell velocity and nanoparticles uptake.