Alicja Rapacz-Kmita

Publikacja stanowi nowoczesny skrypt do zajęć laboratoryjnych z zakresu podstawowych właściwości materiałów inżynierskich, przeznaczony dla studentów kierunków technicznych. Opracowanie powstało na podstawie wieloletniego doświadczenia dydaktycznego oraz badawczego autorów, aktywnie działających w obszarze inżynierii materiałowej, i uwzględnia aktualny stan wiedzy oraz współczesne metody badań materiałowych. Książka została przygotowana w spójnej i przejrzystej formule dydaktycznej. Każdą część opracowano według jednolitego schematu obejmującego cel ćwiczenia, zagadnienia do samodzielnego przygotowania, część teoretyczną oraz szczegółowy opis części praktycznej wraz z zasadami opracowania wyników, a także przykładowe zagadnienia do dyskusji i kontrolne pytania. Każde ćwiczenie zakończone jest spisem literatury poszerzającej wiedzę w danym obszarze. Taki logiczny układ treści ułatwia studentom przygotowanie się do zajęć laboratoryjnych, sprzyja systematyzacji wiedzy oraz kształtuje w uczestnikach zajęć dobre nawyki eksperymentalne i umiejętność analizy wyników. Zakres tematyczny skryptu obejmuje m.in. pomiary podstawowych wielkości geometrycznych, ilościową analizę mikrostruktury materiałów, badanie gęstości i porowatości, zagadnienia związane z właściwościami sprężystymi, cieplnymi, wytrzymałościowymi, termomechanicznymi, a także właściwościami elektrycznymi i optycznymi materiałów. W realizacji ćwiczeń przewidziano wykorzystanie nowoczesnej aparatury badawczej oraz aktualnych modeli naukowych. Publikacja wyróżnia się klarownym, poprawnym językiem, unikającym żargonowych sformułowań charakterystycznych dla wielu technicznych publikacji, i przede wszystkim – wysokim poziomem merytorycznym. Skrypt adresowany jest do studentów studiów I, II i III stopnia kierunków technicznych, w szczególności inżynierii materiałowej, mechanicznej i elektrotechniki, i może stanowić wartościowe wsparcie w prowadzeniu zajęć laboratoryjnych oraz kształceniu praktycznych kompetencji inżynierskich.

The aim of the study was to develop hybrid nanomaterials based on monodisperse silica spheres as carriers for silver nanoparticles (AgNPs) or bismuth nanoparticles (BiNPs) and to evaluate their antimicrobial properties. Silica spheres were synthesized using a modified Stöber method, either unmodified or functionalized with (3-aminopropyl)triethoxysilane (APTES), prior to AgNP or BiNP deposition. The materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), and zeta potential measurements, while antimicrobial activity was assessed by microdilution against Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Enterococcus faecium) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), with Helicobacter pylori as a clinical model. The results show that both SiO₂-AgNP and SiO₂-BiNP composites completely inhibited H. pylori and showed high activity against other pathogens, although P. aeruginosa remained less susceptible. Functionalization of AgNP-coated samples with APTES promoted uniform distribution of AgNPs, with the minimum bactericidal concentration (MBC) to minimum inhibitory concentration (MIC) ratios ranging from 1 to 4, confirming a bactericidal rather than bacteriostatic effect. In contrast, BiNP-coated samples without APTES exhibited lower MIC values from 74 to 595 μg mL⁻¹, consistent with increased Bi³⁺ release from amorphous phases. This indicates the antimicrobial potential, highlighting the role of surface functionalization in regulating ion release and biological performance, and suggesting applications in the biomedical and food industries.

In this study, the properties of electrophoretically deposited (EPD) coatings on orthodontic implants made from Ti-6Al-4V alloy were evaluated during simulated implantation trials on animal bones. Three types of chitosan-based coatings were prepared using EPD: titanium nitride microparticles (TiNPs), titanium nitride nanoparticles (TiNNPs), and boron nitride particles (BNPs). Each of these coatings was also modified by adding a polylactic acid (PLA) layer using a dip-coating technique to compare their properties with and without this additional layer. The coatings were analysed using optical microscopy, confocal microscopy, and scanning electron microscopy (SEM) with elemental analysis. Surface roughness measurements of the coated implants were also conducted to highlight differences that could significantly influence the type and strength of the bone-implant interface, directly affecting the stability of the implant as an anchorage unit. Eventually, to evaluate the antibacterial properties of the EPD coatings, their antibacterial activity against both Gram-positive and Gram-negative bacteria strains was tested. Scanning electron observations confirmed the homogenous distribution of micro- and nanoparticles in all coatings. The highest surface roughness values were observed in layers containing titanium nitride nanoparticles (TiNNPs) and chitosan. The presence of an additional dip-coating PLA layer improved the adhesion, and its effect on the surface roughness depended on the particle size. While the antibacterial properties of the coatings show promising results, achieving optimal adhesion of the coatings to implants remains a challenge that requires further development.

The study examined the possibility of intercalation of montmorillonite with neomycin in an aqueous drug solution and the factors influencing the effectiveness of this process, such as the ion exchange capacity and process conditions, including the time and temperature of incubation with the drug. X-ray diffractometry (XRD), infrared spectroscopy (FTIR), thermal analysis (DSC/TG), and Zeta potential measurement were used to confirm drug intercalation as well as to investigate the nature of clay–drug interactions. The obtained conjugates with the most favorable physicochemical properties were also tested for antibacterial response against Gram-negative bacteria (Escherichia coli) to confirm that the bactericidal properties of neomycin were retained after intercalation and UV–VIS spectrophotometry was used to examine the kinetics of drug release from the carrier. The results of the conducted research clearly indicate the successful intercalation of neomycin in montmorillonite and indicate the influence of process parameters on the properties of not only the conjugates themselves but also the properties of the intercalated drug, particularly its bactericidal activity. Ultimately, a temperature of 50 °C was found to be optimal for effective drug intercalation and the conjugates obtained within 2 h showed the highest antibacterial activity, indicating the highest potential of the thus-obtained montmorillonite conjugates as neomycin carriers.

The aim of the work was to examine the possibility of using modified halloysite nanotubes as a gentamicin carrier and to determine the usefulness of the modification in terms of the effect on the amount of the drug attached, its release time, but also on the biocidal properties of the carriers. In order to fully examine the halloysite in terms of the possibility of gentamicin incorporating, a number of modifications of the native halloysite were carried out prior to gentamicin intercalation with the use of sodium alkali, sulfuric and phosphoric acids, curcumin and the process of delamination of nanotubes (expanded halloysite) with ammonium persulfate in sulfuric acid. Gentamicin was added to unmodified and modified halloysite in an amount corresponding to the cation exchange capacity of pure halloysite from the Polish Dunino deposit, which was the reference sample for all modified carriers. The obtained materials were tested to determine the effect of surface modification and their interaction with the introduced antibiotic on the biological activity of the carrier, kinetics of drug release, as well as on the antibacterial activity against Escherichia coli Gram-negative bacteria (reference strain). For all materials, structural changes were examined using infrared spectroscopy (FTIR) and X-ray diffraction (XRD); thermal differential scanning calorimetry with thermogravimetric analysis (DSC/TG) was performed as well. The samples were also observed for morphological changes after modification and drug activation by transmission electron microscopy (TEM). The conducted tests clearly show that all samples of halloysite intercalated with gentamicin showed high antibacterial activity, with the highest antibacterial activity for the sample modified with sodium hydroxide and intercalated with the drug. It was found that the type of halloysite surface modification has a significant effect on the amount of gentamicin intercalated and then released into the surrounding environment but does not significantly affect its ability to further influence drug release over time. The highest amount of drug released among all intercalated samples was recorded for halloysite modified with ammonium persulfate (real loading efficiency above 11%), for which high antibacterial activity was found after surface modification, before drug intercalation. It is also worth noting that intrinsic antibacterial activity was found for non-drug-intercalated materials after surface functionalization with phosphoric acid (V) and ammonium persulfate in the presence of sulfuric acid (V).

Emulsion electrospinning is a method of modifying a fibers’ surface and functional properties by encapsulation of the bioactive molecules. In our studies, bovine serum albumin (BSA) played the role of the modifier, and to protect the protein during the electrospinning process, the W/O (water-in-oil) emulsions were prepared, consisting of polymer and micelles formed from BSA and anionic (sodium dodecyl sulfate–S) or nonionic (Tween 80–T) surfactant. It was found that the micelle size distribution was strongly dependent on the nature and the amount of the surfactant, indicating that a higher concentration of the surfactant results in a higher tendency to form smaller micelles (4–9 µm for S and 8–13 µm for T). The appearance of anionic surfactant micelles reduced the diameter of the fiber (100–700 nm) and the wettability of the nonwoven surface (up to 77°) compared to un-modified PCL polymer fibers (100–900 nm and 130°). The use of a non-ionic surfactant resulted in better loading efficiency of micelles with albumin (about 90%), lower wettability of the nonwoven fabric (about 25°) and the formation of larger fibers (100–1100 nm). X-ray photoelectron spectroscopy (XPS) was used to detect the presence of the protein, and UV-Vis spectrophotometry was used to determine the loading efficiency and the nature of the release. The results showed that the location of the micelles influenced the release profiles of the protein, and the materials modified with micelles with the nonionic surfactant showed no burst release. The release kinetics was characteristic of the zero-order release model compared to anionic surfactants. The selected surfactant concentrations did not adversely affect the biological properties of fibrous substrates, such as high viability and low cytotoxicity of RAW macrophages 264.7.

The development of new chemically resistant anodes for protonic ceramic fuel cells (PCFCs) is urgently required to avoid the costly deep hydrogen purification method. Ba_0.95Ca_0.05Ce_0.9Y_0.1O_3−δ (5CBCY), which is more chemically resistant than BaCaCe_0.9Y_0.1O_3−δ, was here tested as a component of a composite NiO–5CBCY anode material. A preparation slurry comprising 5CBCY_, NiO, graphite, and an organic medium was tape cast, sintered and subjected to thermal treatment in 10 vol.% H₂ in Ar at 700 °C. Differential thermal analysis, thermogravimetry, quadrupole mass spectrometry, X-ray diffraction analysis, scanning electron microscopy, the AC four-probe method and electrochemical impedance spectroscopy were used for the investigation. The electrical conductivity of the Ni–5CBCY in H₂–Ar at 700 °C was 1.1 S/cm. In the same gas atmosphere but with an additional 5 vol.% CO₂, it was slightly lower, at 0.8 S/cm. The Ni–5CBCY cermet exhibited repeatable electrical conductivity values during Ni-to-NiO oxidation cycles and NiO-to-Ni reduction in the 5CBCY matrix, making it sufficient for preliminary testing in PCFCs.

The paper presents the results of research on the influence of the granulometric composition on the rheological properties of granulates from soft waste produced in the manufacturing of ceramic tiles using the Lamgea and Continua methods in terms of the possibility of their reuse. The composition of the granulates was modified by removing individual grain fractions in three measurement series. Comparatively, the measurement samples for the production granulates were prepared in the same way. Microscopic observations and granulometric analysis showed significant differences in the grain shape and grain size distribution of granulates. The soft waste granulates also showed much worse flow ability than the production granulates. It was shown that the removal of the smallest fractions significantly improved the rheological properties of soft waste granulates. This tendency was also observed in the case of measurements of changes in the bulk density. A Brookfield powder analyzer was used for rheological tests, and a flow analysis was performed using the numerical Jenike classification.

Electrospinning was used to obtain multifunctional fibrous composite materials with a matrix of poly-ɛ-caprolactone (PCL) and 2 wt.% addition of a nanofiller: montmorillonite (MMT), montmorillonite intercalated with gentamicin sulphate (MMTG) or gentamicin sulphate (G). In the first stage, the aluminosilicate gallery was modified by introducing gentamicin sulfate into it, and the effectiveness of the intercalation process was confirmed on the basis of changes in the clay particle size from 0.5 µm (for MMT) to 0.8 µm (for MMTG), an increase in the interplanar distance d₀₀₁ from 12.3 Å (for MMT) to 13.9 Å (for MMTG) and altered clay grain morphology. In the second part of the experiment, the electrospinning process was carried out in which the polymer nonwovens with and without the modifier were prepared directly from dichloromethane (DCM) and N,N-dimethylformamide (DMF). The nanocomposite fibrous membranes containing montmorillonite were prepared from the same polymer solution but after homogenization with the modifier (13 wt.%). The degree of dispersion of the modifier was evaluated by average microarray analysis from observed area (EDS), which was also used to determine the intercalation of montmorillonite with gentamicin sulfate. An increase in the size of the fibers was found for the materials with the presence of the modifier, with the largest diameters measured for PCL_MMT (625 nm), and the smaller ones for PCL_MMTG (578 nm) and PCL_G (512 nm). The dispersion of MMT and MMTG in the PCL fibers was also confirmed by indirect studies such as change in mechanical properties of the nonwovens membrane, where the neat PCL nonwoven was used as a reference material. The addition of the modifier reduced the contact angle of PCL nonwovens (from 120° for PCL to 96° for PCL_G and 98° for PCL_MMTG). An approximately 10% increase in tensile strength of the nonwoven fabric with the addition of MMT compared to the neat PCL nonwoven fabric was also observed. The results of microbiological tests showed antibacterial activity of all obtained materials; however, the inhibition zones were the highest for the materials containing gentamicin sulphate, and the release time of the active substance was significantly extended for the materials with the addition of montmorillonite containing the antibiotic. The results clearly show that the electrospinning technique can be effectively used to obtain nanobiocomposite fibers with the addition of nonintercalated and intercalated montmorillonite with improved strength and increased stiffness compared to materials made only of the polymer fibers, provided that a high filler dispersion in the spinning solution is obtained.