Search Results (38)

This study examines the pigments and materials used in Girolamo Romanino’s Musicians fresco (1537–1538), located in the Duomo Vecchio in Brescia, with the aim of identifying and analyzing the artist’s colour palette. Ten samples of the pictorial layer and mortar were collected from two frescoes and characterized using microscopic and spectroscopic techniques. Confocal laser scanning microscopy (CLSM) was used to define the best positions where single-point, spectroscopic techniques could be applied. Raman spectroscopy and micro-Fourier transform Infrared spectroscopy (micro-FTIR) were used to detect pigments and organic binders, respectively. X-ray powder diffraction (XRPD) provided additional insights into the mineral composition of the pigmenting layers, in combination with environmental scanning electron microscopy equipped with energy-dispersive spectroscopy (ESEM-EDS). The analysis revealed the use of traditional fresco pigments, including calcite, carbon black, ochres, and copper-based pigments. Smalt, manganese earths, and gold were also identified, reflecting Romanino’s approach to colour and material selection. Additionally, the detection of modern pigments such as titanium white and baryte points to restoration interventions, shedding light on the fresco’s conservation history. This research provides one of the most comprehensive analyses of pigments in Romanino’s works, contributing to a deeper understanding of his artistic practices and contemporary fresco techniques. Full article

Carbyne-containing materials offer significant potential for biosensor applications due to their unique chemical and mechanical properties. In this study, carbyne-enriched carbon coatings deposited on SiO₂/Si chips using ion-assisted pulse-plasma deposition were evaluated for the first time as substrates for optical biosensing. At first, the carbyne-enriched coatings were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, Atomic Force Microscopy, and the sessile drop method to assess their composition, structure, and wettability. After that, chips with carbyne-enriched coatings were modified with biomolecules through physical absorption or covalent bonding, and the respective biomolecular interactions were monitored in real-time by White Light Reflectance Spectroscopy (WLRS). In both cases, SiO₂/Si chips modified with an aminosilane were used as reference substrates. Physical adsorption was tested through immobilization of an antibody against C-reactive protein (CRP) to enable its immunochemical detection, whereas covalent bonding was tested through coupling of biotin and monitoring its reaction with streptavidin. It was found that the carbyne-enriched carbon-coated chips retained both their antibody adsorption capability and their covalent bonding ability for over 18 months, while the modified with aminosilane SiO₂/Si chips lost 90% of their antibody adsorption capacity and covalent bonding ability after two months of storage. These findings highlight the strong potential of carbyne-enriched carbon-coated chips as robust biosensing substrates, with applications extending beyond WLRS. Full article

The authenticity of Protected Designation of Origin (PDO) Feta cheese is critical for consumer confidence and market integrity, particularly in light of widespread concerns over economically motivated adulteration. This study evaluated the potential of Attenuated Total Reflectance–Fourier Transform Infrared (ATR-FTIR) spectroscopy combined with chemometric modeling to differentiate authentic Feta from non-Feta white brined cheeses. A total of 90 cheese samples, consisting of verified Feta and cow milk cheeses, were analyzed in both freeze-dried and fresh forms. Spectral data from raw, first derivative, and second derivative spectra were analyzed using principal component analysis–linear discriminant analysis (PCA-LDA) and Partial Least Squares Discriminant Analysis (PLS-DA) to distinguish authentic Feta from non-Feta cheese samples. Derivative processing significantly improved classification accuracy. All classification models performed relatively well, but the PLS-DA model applied to second derivative spectra of freeze-dried samples achieved the best results, with 95.8% accuracy, 100% sensitivity, and 90.9% specificity. The most consistently highlighted discriminatory regions across models included ~2920 cm⁻¹ (C–H stretching in lipids), ~1650 cm⁻¹ (Amide I band, corresponding to C=O stretching in proteins), and the 1300–900 cm⁻¹ range, which is associated with carbohydrate-related bands. These findings support ATR-FTIR spectroscopy as a rapid, non-destructive tool for routine Feta authentication. The approach offers promise for enhancing traceability and quality assurance in high-value dairy products. Full article

This study focused on developing pigmented linear low-density polyethylene (LLDPE) sheets while preserving their mechanical properties and infrared (IR) transparency. Six pigments—ZnO, ZnS, TiO₂, FeO yellow, FeO light brown, and FeO dark brown—were each mixed with polyethylene (PE) wax in a 1:1 ratio and blended with LLDPE at concentrations of 1, 3, and 5 wt%. Tensile strength tests showed minimal changes at lower pigment concentrations, with values near that of pure LLDPE (14 MPa), and slight reductions at 5 wt%. IR transparency tests, conducted using both direct and reflected heat sources, showed that white-pigmented sheets maintained over 85% transparency, while colored pigments exhibited slightly reduced IR transmittance, ranging from 70% to 91%. Fourier Transform Infrared Spectroscopy (FTIR) analysis confirmed that the critical IR transparency range of 8–12 μm remained unaffected with both pure and pigmented sheets. On the other hand, ultraviolet–visible (UV–VIS) testing showed that white-pigmented sheets experienced enhanced visible-light absorption with increasing pigment concentration and thickness, while color-pigmented sheets exhibited high opacity. Additionally, micro-structuring was performed on the LLDPE sheets to further modify their IR properties, which resulted in effective scattering of IR radiation. These findings highlight the potential of pigmented LLDPE sheets for applications requiring both visual opacity and IR transparency, such as thermal management and camouflage, as well as applications requiring tunable IR properties. Full article

The present work investigates the physicochemical stability of spray paints when irradiated with artificial solar light (at spectral range 300–800 nm). This research highlights the importance of understanding the materials used in street art and public murals, recognising them as a significant component of contemporary cultural heritage. By examining the stability and degradation of spray paints toward solar light exposure, the study aims to contribute to the preservation of contemporary murals, which reflect current social and cultural narratives. A physicochemical approach was employed for the study of spray paints’ physical and thermal properties, as well as the effect of specific photochemical ageing reactions/processes. The photochemical ageing results were compared with reference (unaged) samples. Specifically, a multi-technique approach was applied using stereo microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurement, colorimetry, glossimetry, differential scanning calorimetry (DSC), UV-Vis spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and pyrolysis-GC/MS (Py-GC/MS). The photodegradation of the spray paints occurred from the first 144 h of solar light irradiation, resulting in changes in morphology, colour, gloss, roughness, and wettability. Regarding photochemical stability, ageing seems to affect the binders more than the synthetic organic pigments and the inorganic fillers. In particular, acrylic binders showed small chemical changes, whereas the alkyd, nitrocellulose, and styrene binders underwent severe chemical modification. The results suggest that simulated daylight irradiation prompts the migration of additives toward the surface of the spray paint films. In addition, the results of the analyses on the white spray paints in comparison with the coloured paints (from the same manufacturer) showed that there seems to be an active distinct photoageing mechanism involving titanium dioxide, but the whole issue needs further investigation. Full article

The Japanese textile tradition is renowned for its intricate designs achieved through a variety of dyeing techniques, including kasuri, shibori, and paste-resist dyeing. These techniques are often combined within a single textile, resulting in exceptionally elaborate creations. Our paper delves into the technical aspects and complexities of these methods, highlighting the dynamic interplay between tradition and innovation in Japanese textile production. Our scientific endeavour focused on some textiles dating between the 19th and 20th centuries and belonging to the Montgomery Collection of Japanese folk art. Employing non-invasive techniques such as visible reflectance spectroscopy and ER-FTIR spectroscopy, we uncovered key insights into the materials and methods utilized in the creation of these textiles. Our analysis revealed a diverse array of pigments and dyes, including plant-derived, inorganic, and synthetic variants. These findings illuminate the cultural syncretism between traditional Japanese practices and the adoption of new materials from the West, underscoring the dynamic nature of textile production in Japan. Furthermore, ER-FTIR spectroscopy elucidated the predominant use of cotton as the primary fibre in the textiles, aligning with historical records of Japan’s role as a major producer of cotton yarn. Analysis of white areas within the textiles revealed evidence of resist-paste dyeing techniques, particularly tsutsugaki and katazome, through the absence of dye penetration and the characteristic appearance of white lines. Confirmation of indigo dyeing techniques (aizome) was achieved through ER-FTIR spectroscopy, providing reliable identification of indigo and Prussian blue in various shades of blue present in the textiles. Additionally, the detection of Western-derived dyeing method (utsushi-yūzen) and free-hand painting (kaki-e), offers insights into the diversity of dyeing practices employed by Japanese artisans. The presence of proteinaceous materials and synthetic dyes observed in some textiles has implications for conservation practices, suggesting the need for tailored approaches to ensure the preservation of these culturally significant artifacts. Overall, these scientific results shed new light on the materials, techniques, and cultural contexts underlying Japanese textile production, advancing our understanding of this rich artistic heritage and informing future research endeavours in textile science and conservation. Full article

Fine-dispersed YGdAG:Ce nanopowders with various degrees of isomorphic substitution of yttrium by gadolinium were synthesized. The structure and luminescent properties were studied by X-ray diffraction, attenuated total reflection Fourier-transform infrared spectroscopy, luminescence spectroscopy and scanning electron microscopy. The possibility of synthesis of YGdAG:Ce nanopowders with a degree of gadolinium substitution up to 60% and nanocrystals with average sizes of 25–30 nm were shown. The red-shift of the cerium luminescence band with an increase in Gd content was studied. The CIE diagram for emission of YGdAG:Ce synthesized by the polymer–salt method shows that the degree 30–40% substitution of Y by Gd is optimal for the fabrication of a white light source based on LED with an emission wavelength of 470 nm. Full article

Side chains play an important role in the photo-oxidation process of low band gap (LBG) polymers. For example, it has been shown that their photostability can be increased by the introduction of aromatic-oxy-alkyl links. We studied the photostability of prototypical LBG polymers with alkyl and oxyalkyl side chains during irradiation with white light (AM 1.5 conditions) in dry air using UV/vis and IR spectroscopy. Though its degradation kinetics were distinctly affected by the presence or absence of oxygen in the structure of the side chains, in particular cases, the stability was more affected by the presence of linear or branched side chains. Moreover, we showed that the exact position of the alkyl/oxyalkyl side chain at the polymer backbone could be crucial. Although minor effects of chemical modifications on the electronic parameters (ionization potential and gap) were observed, the molecular orientation, determined by polarization modulation-infrared reflection-absorption spectroscopy (PMIRRAS), could be affected. The aggregation and crystallinity of these polymers may distinctly affect their stability. Full article

Designing phosphors that are excited by blue light is extraordinarily important for white light-emitting diodes (w-LEDs). In the present study, a new Ruddlesden–Popper type of SZO:xEu³⁺ (x = 0.01~0.10) phosphors was developed using solid-state reactions. Interestingly, a Eu³⁺ doping-induced phase transformation from the Sr₃Zr₂O₇ (cubic) to the SrZrO₃ (orthorhombic) phase was observed, and the impact of the occupied sites of Eu³⁺ ions on the lifetime of Sr₃Zr₂O₇:xEu³⁺ phosphors is discussed in detail. Diffuse reflectance spectroscopy results showed that the band gap of SZO:xEu³⁺ phosphors gradually increased from 3.48 eV for undoped Sr₃Zr₂O₇ hosts to 3.67 eV for SZO:0.10Eu³⁺ samples. The fluorescence excitation spectrum showed that ultraviolet (300 nm), near-ultraviolet (396 nm) and blue light (464 nm) were all effective excitation pump sources of Sr₃Zr₂O₇:xEu³⁺ phosphors, and the strongest emission at 615 nm originated from an electric dipole transition (⁵D₀→⁷F₂). CIE coordinates moved from orange (0.5969, 0.4267) to the reddish-orange region (0.6155, 0.3827), and the color purity also increased. The fabricated w-LED was placed on a 460 nm chip with a mixture of YAG:Ce³⁺ and SZO:0.1Eu³⁺ samples and showed “warm” white light with a color rendering index (CRI) of 81.8 and a correlation color temperature (CCT) of 5386 K, indicating great potential for application in blue chip white LEDs. Full article

Rhodamine B (RhB) is extensively used for dyeing purposes, and cannot be completely removed using traditional water treatment technologies. Here, we report for the first time the photodegradation of RhB using nitrogen-doped titanium dioxide (N-TiO₂) on reduced graphene oxide (rGO) composite (N-TiO₂/rGO). The work primarily highlights the synergistic effect of the incorporation of N-TiO₂ and rGO and its kinetic study for the photodegradation of RhB. The N-TiO₂/rGO composite was synthesized by dispersing titanium(IV) isopropoxide and urea, followed by annealing treatment via the hydrothermal method with rGO. Scanning electron microscopy (SEM) images illustrated that N-TiO₂ particles with an irregular round shape and white color were dispersed onto the rGO surface. X-Ray diffraction (XRD) patterns revealed that N-TiO₂/rGO composite showed an anatase phase of TiO₂ with a diffraction peak of 2θ = 25.622°. The gas sorption analysis (GSA) showed that N-TiO₂/rGO had surface area, pore volume, and pore size of 53.393 m²/g, 0.096 cc/g, and 3.588 nm, respectively. The thermogravimetric-differential thermal analysis (TG-DTA) showed an anatase phase of TiO₂ that appeared at a temperature of 200–500 °C, with a weight loss of 2.50%. According to the ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) study, TiO₂, N-TiO₂, and N-TiO₂/rGO had band gap energies of 3.25, 2.95, and 2.86 eV, respectively. The highest photodegradation of RhB was obtained at the optimum condition in pH 2 with a photocatalyst mass of 20 mg and an irradiation time of 90 min. The photocatalytic activity of N-TiO₂/rGO using visible light showed a higher percentage of photodegradation at 78.29%, compared to 44.08% under UV light. The kinetic study of the photodegradation of RhB using N-TiO₂/rGO followed the pseudo-second-order model. Full article

The paper presents the application of the acousto-optic tunable filter (AOTF) in surface plasmon resonance (SPR) spectroscopy to measure the optical thickness of thin dielectric coatings. The technique presented uses combined angular and spectral interrogation modes to obtain the reflection coefficient under the condition of SPR. Surface electromagnetic waves were excited in the Kretschmann geometry, with the AOTF serving as a monochromator and polarizer of light from a white broadband radiation source. The experiments highlighted the high sensitivity of the method and the lower amount of noise in the resonance curves compared with the laser light source. This optical technique can be implemented for nondestructive testing in the production of thin films in not only the visible, but also the infrared and terahertz ranges. Full article

A nanocomposite (NC) of titanium (IV) oxide (TiO₂) and molybdenum (VI) oxide (MoO₃) was synthesized using a hydrothermal route. Detailed analyses using transmission electron microscopy, X-ray diffraction, X-ray fluorescence (XRF), Brunauer–Emmett–Teller (BET) isotherms, X-ray photoelectron spectroscopy, Raman, and diffuse reflectance infrared Fourier transform spectroscopy were carried out and confirmed the successful formation of pure TiO₂-MoO₃ (Ti-Mo) NC. The Ti-Mo NC possesses sizes in the range of 150–500 nm. XPS, Raman, and DRIFT shift measurements confirmed the formation of mixed oxide linkage in the form of Ti-O-Mo. Sorption of nitrogen isotherms revealed a significant increase in the number and pore widths of mesopores in the NC. Water sorption isotherms revealed enhanced affinity of the nanocomposites for water relative to the pure metal oxides. The BET surface area for Ti-Mo NC from the nitrogen adsorption isotherm was 129.3 m²/g which is much higher than the pure metal oxides (i.e., 37.56 m²/g for TiO₂ and 2.21 m²/g for MoO₃). The Ti-Mo NC provided suitable adsorption sites that captured the studied carbamates from the solution and promoted their photodegradation process. The photocatalytic degradation of MB in the presence of the catalyst was enhanced by 2.9 and 5.5 folds upon irradiation with white LED and 302 nm UV light sources, respectively. Full article

Surgical treatment is widely applied curative approach for bladder cancer. White light cystoscopy (WLC) is currently used for intraoperative diagnostics of malignant lesions but has relatively high false-negative rate. Here we represent an application of label free fiber-based attenuated total reflection infrared spectroscopy (ATR IR) for freshly resected human bladder tissue examination for 54 patients. Defined molecular spectral markers allow to identify normal and urothelial carcinoma tissues. While methods of statistical analysis (Hierarchical cluster analysis (HCA) and Principal component analysis (PCA)) used for spectral data treatment allow to discriminate tissue types with 91% sensitivity and 96–98% specificity. In the present study the described method was applied for tissue examination under ex vivo conditions. However, after method validation the equipment could be translated from laboratory studies to in situ or even in vivo studies in operating room. Full article

Ochratoxin A (OTA) is one of the most toxic naturally encountered contaminants and is found in a variety of foods and beverages, including cereals and wine. Driven by the strict regulations regarding the maximum allowable OTA concentration in foodstuff and the necessity for on-site determination, the development of fast and sensitive methods for the OTA determination in cereal flours and wine samples, based on white light reflectance spectroscopy, is presented. The method relied on appropriately engineered silicon chips, on top of which an OTA-protein conjugate was immobilized. A polyclonal antibody against OTA was then employed to detect the analyte in the framework of a competitive immunoassay; followed by the subsequent addition of a biotinylated secondary antibody and streptavidin for signal enhancement. A small size instrument performed all assay steps automatically and the bioreactions were monitored in real time as the software converted the spectral shifts into effective biomolecular adlayer thickness increase. The assay developed had a detection limit of 0.03 ng/mL and a working range up to 200 ng/mL. The assay lasted 25 min (less than 1h, including calibrators/antibody pre-incubation) and was accomplished following a simple sample preparation protocol. The method was applied to corn and wheat flour samples and white and red wines with recovery values ranging from 87.2 to 111%. The simplicity of the overall assay protocol and convenient instrumentation demonstrates the potential of the immunosensor developed for OTA detection at the point of need. Full article

Pampaloite AuSbTe, a rare gold-antimony telluride that was first described in 2019 from the Pampalo gold mine, Finland, was found in samples from the large Svetlinsk gold-telluride deposit, South Urals, Russia. Optical microscopy, scanning electron microscopy, electron microprobe analysis, reflectance measurements, electron backscatter diffraction and Raman spectroscopy were used to study eight grains of pampaloite. Pampaloite forms inclusions (5–30 μm) in quartz together with other tellurides (typically petzite), native gold and, less often, sulfides. In reflected light, pampaloite is white or creamy white in color with weak anisotropism and without internal reflections. The empirical formula calculated on the basis of 3 apfu is Au_0.97–1.07Ag_0–0.02Sb_0.96–1.04Te_0.96–1.04 (n = 18). The holotype pampaloite structure was used as a reference and provided the perfect match for an experimental EBSD pattern (12 bands out of 12, mean angle deviation 0.19°). Raman spectra are reported for the first time for this mineral. All studied pampaloite grains exhibit vibrational modes in the range 60–180 cm⁻¹. Average peak positions are 71, 108, 125, 147 and 159 cm⁻¹. According to experimental data for the Au-Sb-Te system, we estimate the upper temperature range of pampaloite crystallization at the Svetlinsk deposit to be 350–430 °C. Full article