Polymer nanocomposites have been extensively researched for a variety of applications, including medical osteoregenerative implants. However, no satisfactory solution has yet been found for regeneration of big, and so-called critical, bone losses. The requirement is to create a resorbable material which is characterised by optimum porosity, sufficient strength, and elastic modulus matching that of the bone, thus stimulating tissue regrowth. Inverse nanocomposites, where the ceramic content is larger than the polymer content, are a recent development. Due to their high ceramic content, they may offer the required properties for bone implants, currently not met by polymer nanocomposites with a small number of nanoparticles. This paper presents inverse nanocomposites composed of bioresorbable nano crystalline hydroxyapatite (HAP NPs) and polylactide (PLLA), produced by cryomilling and a warm isostatic pressing method. The following compositions were studied: 25%, 50%, and 75% of HAP NPs by volume. The mechanical properties and structure of these composites were examined. It was discovered that 50% volume content was optimal as far as compressive strength and porosity are concerned. The inverse nanocomposite with 50% nanoceramics volume displayed a compressive strength of 99 ± 4 MPa, a contact angle of 50°, and 25% porosity, which make this material a candidate for further studies as a bioresorbable bone implant.

Incorporating nanoparticles into denture materials shows promise for the prevention of denture-associated fungal infections. This study investigates the antifungal properties of acrylic modified with microwave-sintered ZnO-Ag nanoparticles. ZnO-Ag nanoparticles (1% and 2.5% wt.) were synthesized via microwave solvothermal synthesis (MSS). Nanoparticles were characterized for phase purity, specific surface area (SSA), density, morphology, and elemental composition. ZnO and ZnO-Ag nanoparticles were added to acrylic material (PMMA) at concentrations of 1% and 2.5% and polymerized. Pure PMMA (control) and obtained PMMA-nanocomposites were cut into homogeneous 10 × 10 mm samples. Antifungal activity of nanoparticles and PMMA-nanocomposites against C. albicans was tested using minimal inhibitory concentration (MIC) determination, and biofilm formation was assessed using crystal violet staining followed by absorbance measurements. Laboratory tests confirmed phase purity and uniform, spherical particle distribution. MIC results show antifungal activity of 1% Ag nanoparticles and the PMMA-2.5% (ZnO-1% Ag) nanocomposite. PMMA-1% (ZnO-1% Ag) nanocomposite and 1% ZnO-Ag nanoparticles are efficient in preventing biofilm formation. However, ZnO nanoparticles showed antibiofilm activity, and the PMMA-ZnO nanocomposite does not protect against biofilm deposition. Incorporating hybrid ZnO-Ag nanoparticles into PMMA is a promising antibiofilm method, especially with ZnO-1% Ag nanoparticles.

Air pollution with particulate matter from transport sources is a serious problem in terms of air quality and its impact on human health. The article attempts to test the emitted particles from piston engines in terms of their physical properties and chemical composition. The research test objects were a diesel engine with Euro 5 emission class and a petrol engine, which was a part of the scooter drive system. The conducted research consisted in the analysis of the number, mass, and volume of particles, as well as chemical analysis, using the methods: Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope with Energy Dispersive Spectroscopy (SEM-EDS), and Evolved gas analysis (EGA). The diesel engine emitted particles in the range of 50–120 nm. With the increase in the engine load, the specific emission of particulate matter increased. In the case of a gasoline engine running without load, the emission of particles smaller than 30 nm was mainly observed. Increasing load of the gasoline engine resulted in an increase in both the concentration of particles and their diameter (average diameter to 90 nm). FTIR analysis showed higher black carbon content in the case of the sample taken from the diesel engine. In order to carry out a more detailed chemical analysis, the EGA and SEM methods were used. On their basis, the chemical composition of particles was presented, and a greater ability to agglomerate of a gasoline engine particles was found.