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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. [ABSTRACT FROM AUTHOR]

The combination of spectral and chemometric methods to obtain information of the samples appears to be useful in forensic analysis of questioned documents. In this paper, the application of non-destructive method including FTIR spectroscopy in combination with principal component analysis (PCA) and multivariate analysis of variance (MANOVA) to differentiate black laser prints was investigated. A set of 49 types of laser printers of 10 brands was investigated. PCA was applied to identify the differences between the laser toner samples. PCA of laser prints spectra was used as a base of the method for toner identification. The difference between the spectra of the unknown print and the spectra of the database was tested. The method was confirmed by the analysis of four test prints. A model document printed on three different printers was prepared. The MANOVA test together with PCA scatter diagram confirmed that the model document was printed on three different printers. [ABSTRACT FROM AUTHOR]

Raman spectroscopy and surface enhanced Raman spectroscopy were used to examine 14 blue inks obtained from commercially available stationery. Standard colouring agents in the inks: β-phase of phtalocyanine blue PB15 and some homologues of the methyl violet class, were identified. Surface enhanced Raman spectra were recorded on a firm heterostructure of silver/nanocrystalline diamond/silicon constituting an active substrate providing the possibility to write directly on the surface. Based on the differences in traditional and surface enhanced Raman spectra, two inks were identified unambiguously, the remaining inks were categorised into three groups exhibiting common spectral features. Despite their similarity, surface enhanced Raman spectra exhibited soft variations enabling discrimination of the inks, thus proving the usefulness of the method. [ABSTRACT FROM AUTHOR]

A method has been developed for identification of corrosive iron-gall inks in historical drawings and documents. The method is based on target-factor analysis of visible-near infrared fibre optic reflection spectra (VIS-NIR FORS). A set of reference spectra was obtained from model samples of laboratory-prepared inks covering a wide range of mixing ratios of basic ink components deposited on substrates and artificially aged. As criteria for correspondence of a studied spectrum with a reference spectrum, the apparent error in target (AET) and the empirical function SPOIL according to Malinowski were used. The capability of the proposed tool to distinguish corrosive iron-gall inks from bistre and sepia inks was evaluated by use of a set of control samples of bistre, sepia, and iron-gall inks. Examples are presented of analysis of historical drawings from the 15th and 16th centuries and written documents from the 19th century. The results of analysis based on the tool were confirmed by XRF analysis and colorimetric spot analysis. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Three sets of titanium oxide layers with different oxygen content were prepared by DC pulsed reactive magnetron sputtering. The layers were characterised by their thickness, conductivity, refractive index, band-gap and flat band potential. The photoelectric and photocatalytic activities of the layers irradiated by Xe discharge lamp were tested in NaOH and phenol water solution, respectively. Rather high activity of prepared layers was found; no expressive activity increase was, however, observed in contrary to the expectation connected with suboxide forms of TiO x. [ABSTRACT FROM AUTHOR]