In protecting cultural heritage, deacidification is used to stabilize acidic papers, ensuring the neutralization of acids present in the paper. But in the process of aging, several mechanisms of degradation occur simultaneously. Therefore, substances used to stabilize the paper should contain an antioxidant component in addition to the deacidifying component. The effect of the antioxidant (hindered amine light stabilizers—HALS type) on the stabilization of lignin-containing acid papers during accelerated aging was studied in this work. The effective deacidification component was magnesium; the solvent was hexamethyldisiloxane (HMDSO). The 4-amino-2,2,6,6-tetramethylpiperidine series of hindered amine light stabilizers (HALS) was selected as appropriate for creating a modifying system based on HMDSO. The modification system was tested on samples of a model test acid lignin-containing paper (NOVO) and naturally aged acidic paper from the real book. The addition of substances to the proposed deacidification system has a favorable effect on stabilizing the pH during aging and provides the inhibition of the oxidative degradation products and stabilization of the cellulose degree of polymerization. It was confirmed that the application of the system containing deacidification and an antioxidant component may increase the effectiveness of the protection of acid groundwood paper heritage objects. Adding a tested antioxidant to the proposed deacidification system has a favorable effect on stabilizing the pH value for a long time in accelerated aging.

This study aims to study the possibility of distinguishing the UV–Vis–NIR spectra of filamentous fungi on a paper substrate from the background. Model samples of five filamentous fungi were used: Alternaria alternata, Aspergillus niger, Cladosporium herbarum, Penicillium chrysogenum, and Trichoderma atroviride. The model samples were cultivated on paper substrates, and two methods, cross-validation (CV) and principal component analysis (PCA), were utilised to compare their spectra with the reference background spectra. The results of the CV analysis indicated that certain combined spectra sets of Cladosporium herbarum, Penicillium chrysogenum, Trichoderma atroviride, Aspergillus niger, and Alternaria alternata, at specific surface concentrations, exhibited two active components, signifying distinguishable differences from the background spectra. Additionally, the score scatter diagrams derived from PCA revealed clusters of samples, further confirming the distinguishability of the filamentous fungi spectra from the background. However, for Trichoderma atroviride, the scatter diagram demonstrated a relatively large scattering of points, impeding the resolution of spectra with a surface concentration of 2 10⁵ cm⁻² due to measurement inaccuracies. Based on the combined results of CV and PCA, the study concluded that the lower threshold of measurability for UV–Vis–NIR spectra varied among the different filamentous fungi. For example, Cladosporium herbarum, Penicillium chrysogenum, and Trichoderma atroviride exhibited a threshold around a surface concentration of 2 10⁶ cm⁻², while Aspergillus niger had a threshold around 2 10⁵ cm⁻², and Alternaria alternata had a threshold around 2 10³ cm⁻². In summary, this research provides insights into the distinguishability of filamentous fungi spectra on the paper substrate from background spectra using spectral analysis techniques, offering potential applications in fungal identification and characterisation.

The research aims to find out the crucial factors in the design phase of packaging products, which are related to the determination of environmental influences on sustainable materials. The paper presents the results of research into the influence of environmentally friendly cardboard and the separation of yellow offset ink on the optical properties of prints exposed to thermal aging without and with exposure to NO₂. The samples were obtained under real conditions on a Roland 705 printing machine. The colorimetric characteristics of the print and its stability were determined in the research. The research is significant for graphic reproduction in the domain of testing the quality of the print itself, which is defined by certain raster characteristics. The research covers prints in 100%, 70% RTV, 50% RTV, and 30% RTV. The intensity of the tonal experience will depend on the interaction of the substrate with the raster and different types of inks in offset printing as a function of the experimental conditions. The ink characteristics of prints ∆L*, ∆a*, ∆b*, and ∆E were determined. The research results show that ink I1, with about 80% renewable raw materials, achieves the best stability under the specified experimental conditions.