Search Results (320)

The conservation of the UNESCO World Heritage site of the Sassi di Matera requires an evaluation of consolidation strategies for Gravina calcarenite, a highly porous calcareous stone extensively used in the historic built environment. The pore system, characterized by a predominance of macropores combined with a significant microporous fraction, plays a key role in the performance and long-term behaviour of consolidating agents. Although consolidation treatments have been widely investigated for carbonate stones, studies specifically addressing Gravina calcarenite remain relatively limited. This study presents a comparative assessment of the performance and durability of four commercially available strengthening agents: an ethyl silicate-based product, two nanolime formulations, and a nanosilica-based treatment. The products were applied to Gravina calcarenite and evaluated using a multi-analytical approach integrating mercury intrusion porosimetry, water absorption assessed by the contact sponge method, ultrasonic pulse velocity (UPV), colorimetric measurements, and artificial aging tests. The results reveal distinct performance trends: the ethyl silicate-based product shows the most pronounced immediate reduction in water absorption, together with a consistent increase in UPV, although these effects are not retained after aging. The more concentrated suspension of Ca(OH)₂ nanoparticles (50–250 nm) exhibits a moderate reduction in water absorption with limited chromatic impact, although a decrease in effectiveness emerges after aging. In contrast, the Ca(OH)₂ nanoparticle suspension (100–300 nm), dispersed in isopropanol at a concentration of 5 g/L, shows more limited and variable changes across the investigated parameters. The nanosilica-based treatment shows a reduction in water absorption and the largest mean increase in UPV after application, although with greater variability among specimens, together with modifications in the finer and intermediate pore fractions. None of the investigated products provided a uniform and persistent improvement across all evaluated parameters. Overall, the evaluation of the investigated properties provides a basis for assessing treatment performance and supporting informed conservation strategies. Full article

Self-injection-locked (SIL) VCSELs enable optically coupled apertures to operate as a coherent supermode, combining the high power of multi-aperture devices with quasi-single-mode emission, narrowing far-field beam divergence, and simplified coupling into single-mode fiber. In this work, SIL VCSELs operating near 850 and 880 nm were characterized to examine whether their chirp properties remain favorable for extended-reach short-wavelength transmission. More than 29% coupling efficiency into a single-mode fiber (Hi780) was achieved for both devices using a two-lens coupling arrangement. Link transfer functions were measured over a long single-mode fiber, Hi780, and via a standard single-mode fiber, with fundamental-mode launch via a spliced section of Hi780. The dominant transient chirp behavior is preserved for SIL VCSEL similar to the case of single-mode (SM) VCSEL and multi-aperture (MA) SM VCSELs. A unified full-spectrum fitting method was introduced to extract physically consistent chirp and chromatic-dispersion parameters from shallow transfer-function dips, with the chirp parameter determined to be approximately −2.6. Using the 850 nm SIL VCSEL, 32G NRZ transmission over 1 km of a standard single-mode fiber with fundamental mode launch was demonstrated. Compared with the back-to-back configuration, the 1 km link produced a more open eye and improved 7-tap FFE equalized Gaussian BER from 7.56 × 10⁻¹³ to 1.53 × 10⁻¹⁴, confirming chirp–dispersion-induced bandwidth enhancement. Full article

Pectin films are promising renewable materials for biodegradable coatings; however, their high hydrophilicity and limited resistance to ultraviolet (UV) radiation restrict practical applications. This work investigated the influence of kraft lignin (0–5 wt%) on the structure–property relationships of grape-derived pectin films before and after accelerated UV exposure. Structural organization (XRD and FTIR), photostability (CIELAB colorimetry and CIE chromaticity), wettability, water-vapor absorption, surface morphology, soil-burial disintegration, and integrated multifunctional performance were evaluated. Lignin improved resistance to UV-induced structural changes, reducing the relative loss of apparent crystallinity from 52.76% for neat pectin to less than 7% for films containing at least 0.1 wt% lignin, while substantially decreasing UV-induced color changes. Increasing lignin content also reduced surface wettability, water-vapor uptake, and soil-burial mass loss; nevertheless, all formulations exhibited more than 50% mass loss after 120 h of soil burial. Exploratory CRITIC–TOPSIS analysis identified Pec/Lig₁ as the highest-performing formulation, whereas Pec/Lig_0.1 provided the most compositionally efficient balance among photostability, moisture resistance, structural stability, soil-burial disintegration, and lignin consumption. These findings demonstrate that lignin governs the trade-offs among structural stability, photostability, moisture resistance, soil-burial disintegration, and additive consumption, establishing composition–structure–property–durability relationships that provide practical design guidance for candidate functional coatings for cellulose- and paper-based substrates. Full article

Soy protein, apple fiber, and corn starch are widely used functional ingredients, yet their combined effects on food matrix properties remain poorly characterized. A D-optimal mixture design (16 runs) was used to evaluate how these three components, individually and in binary and ternary combinations, determine the proximate composition, CIELab color parameters, and techno-functional properties (water and oil absorption and solubility, pH, apparent density, emulsifying and foaming capacity, least gelation concentration, and foam stability over 120 min) of model blends. Response surface models were statistically significant for 19 of the 21 responses evaluated (R² = 0.70–1.00, p ≤ 0.05); water and oil absorption capacity did not reach significance (R² = 0.66–0.72, p > 0.05). Formulation was the main driver of the system’s behavior. Starch increased moisture, carbohydrate content, and lightness; protein determined ash, protein content, and water solubility; and fiber dominated crude fiber, lipid content, and red–yellow chromaticity, producing the greatest total color difference relative to pure starch. Unlike composition and color, which followed largely additive, single-ingredient-driven trends, interfacial functionality was governed by strong binary interactions: a synergistic protein–fiber interaction dominated emulsifying capacity (positive) and foaming capacity (strongly negative, almost completely suppressing foam formation even at protein levels comparable to the pure-protein vertex), while a synergistic protein–starch interaction enhanced foam stability. Water and oil absorption capacities varied within narrow, statistically non-significant ranges, indicating structural rather than compositional control. These findings show that mixture design and response surface methodology can quantitatively predict and tune the physicochemical, color, and functional performance of protein–fiber–starch blends, providing a practical framework for designing plant-based functional ingredients with targeted nutritional and technological profiles. Full article

A CMY palette of ceramic pigments was synthesized using both microwave-assisted firing (800 W, 30 min) and conventional electric firing (1000 °C for 3 h). For the allochromatic vanadium-zircon system (including the non-mineralized green and halide-mineralized blue compositions), as well as the chromium-doped scheelite yellow pigment, microwave firing does not outperform conventional calcination. Although comparable reactions occur during synthesis, microwave firing produces powders with lower colour performance. Nevertheless, these differences become visually negligible after incorporation into glazes. This behaviour can be attributed to the low dopant concentration and the localized, selective heating characteristic of microwave irradiation. In the vanadium-zircon system, the microwave-mineralized sample exhibits features similar to those of the non-mineralized compositions, including lower reactivity, smaller crystallite size, and enhanced blue colour development when applied in glazes. In contrast, for the idiochromatic Zn(Al_1.3Fe_0.5Cr_0.2)O₄ spinel red-brown pigment, microwave firing yields superior colour performance compared with conventional electric firing, producing higher chroma and greater colour intensity. In idiochromatic pigments, the relatively high proportion of chromophore components promotes more homogeneous microwave absorption and heating throughout the precursor mixture. The enhanced colour properties achieved through microwave synthesis may indicate the presence of a beneficial non-thermal microwave effect, leading to improved chromatic performance. Full article

Copper and its alloys are indispensable for electronics, communications, new energy systems, and aerospace engineering due to their exceptional electrical conductivity and mechanical properties. However, the thin cuprous oxide (Cu₂O) layer that naturally forms on copper and its alloys is prone to failure under elevated temperatures and high humidity, particularly in chloride-rich environments, leading to accelerated localized corrosion. While conventional chromate-based passivation has long been the industrial standard for preventing corrosion, its use has been increasingly restricted by global regulations (such as RoHS and REACH) due to its severe toxicity and health risks. To address the conflict between environmental compliance and protective performance, this review systematically evaluates recent advances in environmentally friendly, chromium-free anti-corrosion coatings in the present review. These alternative coatings are critically analyzed and categorized into four mechanistic groups: (i) inorganic conversion coatings (including molybdate, tungstate, rare earth, and phosphate systems); (ii) organic films formed via chemical or physical adsorption (such as organic inhibitors, thiol-based monolayers, and organosilane self-assembled films); (iii) conversion coatings engineered through covalent bonding, coordination chemistry, and microstructural tailoring; and (iv) multifunctional coatings that integrate self-healing capability with high electrical conductivity. Beyond providing a technical summary, this review explored how the swift progression of electronic information technology, new energy infrastructure, and robotics has imposed more exacting, multifunctional demands on copper components. This review provides a strategic roadmap for future research and prioritizes the creation of protection strategies that operate robustly in multi-physics coupling environments—integrating high conductivity, autonomous self-healing, and long-term chemical stability to ensure the reliability of next-generation infrastructure. Full article

Layered double hydroxides (LDHs) are functional materials with tunable structural, surface, and adsorption properties. In this study, multicationic LDHs were synthesised and evaluated as adsorbents for chromate(VI). Among the investigated materials, the tetracationic Mg₂Cu_0.5Zn_0.5Al₁ composition exhibited consistently high mass-normalised Cr(VI) uptake in the screening experiments and was therefore selected for detailed investigation. Therefore, its chloride and carbonate forms were selected as model materials to examine the role of interlayer anions in Cr(VI) uptake and pH-dependent stability. The chloride form exhibited a higher adsorption capacity (70 mg/g) than the carbonate form (34 mg/g), indicating that more weakly bound interlayer anions may increase the accessibility of adsorption sites and promote anion exchange during adsorption. In contrast, the carbonate form showed greater structural stability, as confirmed by reduced cation leaching over a wide pH range. The behaviour of Cr(VI) in equilibrium solution was analysed as a function of its initial concentration, which allowed a simple description of Cr(VI) sorption over a wide range of initial pH values. XRD, FTIR, and XPS analyses supported partial interlayer anion exchange and changes in the coordination environment of surface metal centres after Cr(VI) sorption. Adsorption energies of 13–16.4 kJ/mol further suggested that Cr(VI) uptake cannot be assigned to a single interaction type but involves electrostatic interactions, anion exchange, and surface complexation. These results demonstrate that the interlayer anion is a key factor governing both the Cr(VI) adsorption efficiency and aqueous stability of LDH-based adsorbents. Full article

Although the modification of resin composites with antimicrobial agents represents a viable alternative for biofilm inhibition, these changes may compromise the optical and mechanical properties of dental restorations. This in vitro pilot study evaluated the effect of incorporating Nano-Silver Fluoride (NSF) containing 2000 ppm silver nanoparticles (AgNPs) on the microhardness and color of flowable resin composites: Vittra APS Unique Flowable (VA), Filtek Bulk Fill Flowable (FB), and Filtek Supreme Flowable (FS). The resin composites were modified by adding 1 wt%, 2 wt%, and 4 wt% NSF and compared with an unmodified group (control). NSF was characterized by UV–visible spectroscopy and transmission electron microscopy. The specimens were subjected to Vickers microhardness testing and color analysis using the CIEDE2000 (ΔE₀₀) and CIELAB (ΔE) systems. NSF incorporation had a material-dependent effect on microhardness. The VA group showed a progressive reduction in microhardness with increasing NSF additions, whereas the FS group remained unchanged up to the concentration of 2 wt%, and the FB group showed no significant reduction in microhardness at any of the tested concentrations compared with the control (p = 0.549). All resin composites exhibited clinically relevant color changes that increased with the NSF concentration, with more pronounced color changes in the VA group, whereas FB and FS did not vary significantly with the addition of different NSF concentrations. Overall, NSF mainly affected the optical properties, with esthetic limitations being the main challenge to be overcome in further studies. The FB and FS groups at 1 wt% and 2 wt% showed smaller chromatic changes than VA, without compromising microhardness, and appear promising for future investigations, including antimicrobial and cytotoxicity analyses. Full article

Ulluco (Ullucus tuberosus), the second most economically important Andean tuber after potato, has been cultivated for over 5500 years. Despite its resistance to frost, drought, and high altitudes, as well as its biochemically complex profile, ulluco remains underrepresented in the scientific literature and absent from international markets. This comparative review synthesises the evidence available up to November 2025 regarding its biology, nutritional profile, phytochemistry, and food industry applications relative to four other Andean tubers: oca (Oxalis tuberosa), mashua (Tropaeolum tuberosum), native potato (Solanum tuberosum L.), and yacon (Smallanthus sonchifolius). The main comparative findings are as follows: First, ulluco is the only Andean tuber that biosynthesises betalains instead of anthocyanins, producing up to 32 distinct compounds that are stable across a pH range of 3–7, a chromatic stability advantage over anthocyanin-based pigments from mashua, oca, and native potato, which suggests its potential as a source for the development of clean-label natural colourants. Second, among the five species evaluated, ulluco protein content across different morphotypes ranges from 5.60 to 15.7 g/100 g dry weight, ranking within the upper range of values reported for mashua and oca, and comparable to or higher than the upper ranges reported for native potato and yacon. This variability reflects the genotypic and ecogeographical diversity of the evaluated accessions and is not a methodological inconsistency, with 20% of varieties exceeding 10 g/100 g and providing six essential amino acids, supporting genetic improvement programmes aimed at nutritional security. Third, ulluco starch exhibits a low gelatinisation temperature (56–60 °C), a high amylose content (24–36%), and pseudoplastic behaviour, properties comparable or superior to potato starch for specific applications, with technical viability validated at a laboratory scale in applications including biodegradable films, food 3D printing inks, and dehydrated snacks. Unlike yacon, which accumulates fructooligosaccharides and lacks starch, ulluco aligns with oca, mashua, and potato as a starch-accumulating species. Critical gaps identified include the absence of clinical evidence on betalain bioavailability, the lack of a complete nuclear genome assembly, and the non-existence of standardised processing methods for industrial scaling. A coordinated agenda that integrates clean seed programmes, pilot-scale validation, and genomic breeding is essential for the bioeconomy of the 21st century to transform ulluco into a high-value ingredient. Full article

Correlated color temperature (CCT) can substantially influence image-based color measurements, though its effects vary with the optical and physical properties of the meat surface being evaluated. This study investigated the effects of CCT on the image-based color properties of skinless chicken breast and skin-on drumstick samples. It evaluated the suitability of 6500 K as a reference condition. Seventeen skinless breast and seventeen skin-on drumstick samples were repeatedly photographed under 13 CCT conditions ranging from 2500 to 8500 K at 500 K intervals, producing 442 observations. Camera settings, imaging geometry, illuminance, and sample position were maintained constant. Image-derived L*, a*, and b* values were obtained using the Fiji freeware program, and chroma (C*), whiteness index (WI), yellowness index (YI), browning index (BI), and total color difference (ΔE*ab) relative to 6500 K were calculated. Data were analyzed using linear mixed models, and the common variation in L*, a*, and b* was summarized by principal component analysis. Sample type, CCT, and their interaction significantly affected all evaluated parameters (p < 0.001). Increasing CCT generally increased L* and WI, while a*, b*, C*, YI, and BI decreased markedly, indicating a transition toward a lighter and less chromatic image-derived appearance. The largest deviations from the 6500 K reference occurred at 2500 K, with ΔE*ab values of 42.86 and 43.57 for breast and drumstick samples, respectively. Even at 6000 K, only 500 K below the reference condition, ΔE*ab exceeded 4.0 in both breast and drumstick samples, indicating visually perceptible color differences. Visually relevant differences also persisted above 6500 K. The first principal component explained 86.89% of the total variance and described the coordinated increase in lightness and reduction in redness and yellowness with increasing CCT. These findings demonstrate that CCT is a major source of systematic variability in image-based poultry color analysis workflow; therefore, 6500 K should not be treated as a universal reference unless the complete illumination, camera, calibration, and image-processing protocol is standardized and validated for the specific poultry surface being examined. Full article

In this work, we introduce and study a generalization for r-uniform hypergraphs of complement-reducible graphs, the so-called co-graphs. The operations for r-join-hypergraphs are the binary disjoint union of two given r-join-hypergraphs and the r-nary join, which inserts all possible hyperedges of cardinality r, each including exactly one vertex from each of r given r-join-hypergraphs. We characterize the primal graphs of r-join-hypergraphs as special co-graphs and give some properties of r-join-hypergraphs. This allows us to give a method that decides whether an r-uniform input hypergraph H is an r-join-hypergraph and, in the case of an affirmative answer, finds a decomposition tree for H in polynomial time. This task proved to be challenging. We show specific formulas for computing various hypergraph parameters for r-uniform hypergraphs defined by the binary disjoint union of two r-uniform hypergraphs and the r-nary join of r r-uniform hypergraphs. The parameters considered are the size of a largest stable set, the size of a largest co-stable set, the size of a largest independent set, the size of a largest co-independent set, the size of a smallest vertex cover, the size of a smallest 2-transversal, the size of a largest matching, the size of a smallest dominating set, the chromatic number, the strong chromatic number, and the upper chromatic number. This yields $\mathcal{O}(n·r)$-time algorithms to compute these values on r-join-hypergraphs on n vertices given by a decomposition tree. Of particular interest is the development of an efficient algorithm to compute the size of a largest matching. In addition, we infer relations among the considered parameters restricted to r-join-hypergraphs. Our methods generalize and reprove a number of results that are known for co-graphs. Full article

Building-integrated photovoltaics (BIPV) require front-glass materials that satisfy both aesthetic and functional requirements. In this study, colored glass for BIPV applications was fabricated on indium tin oxide (ITO)-coated glass substrates using Radio-Frequency (RF) magnetron sputtering with various ceramic targets, including metal oxides (MoO₃, WO₃, and SiO₂), a nitride (TiN), and Si. The fabricated samples were classified into red, yellow, and blue color families and evaluated in terms of optical transmittance, sheet resistance, and colorimetric properties. The color characteristics were quantitatively analyzed using CIELAB coordinates (L^*, a^*, and b^*) and CIE 1931 chromaticity coordinates (x, y). The results showed that the chromaticity distributions followed continuous material-dependent trajectories rather than random dispersion. Oxide-based coatings generally shifted toward the yellow region with relatively high lightness, whereas TiN-based coatings shifted toward the blue region with reduced lightness. In addition, transmittance analysis in the photovoltaic-relevant spectral range indicated that Si-based coatings exhibited relatively high optical transparency. The observed color variations are consistent with thin-film interference and the optical properties of the coating materials. This study focuses on the comparative evaluation of optical, electrical, and colorimetric characteristics. This study provides a comparative framework for color realization analysis and offers practical guidance for material selection in colored BIPV glass design. Full article

This study evaluated the influence of post-polymerization duration and a 14-day aging period on the mechanical and physical properties of 3D-printed standard resin models. Methods: Specimens were printed using Anycubic resin (50 µm layers) and post-cured for 5, 7, and 10 min. Evaluations included mass variation, chromatic stability, confocal microscopy, and point-indentation tests using a Kistler 9257B dynamometer. Extended post-curing significantly enhanced structural stability. The 10-min aged group (O10) achieved the highest failure threshold at 1862.93 N (a 44% increase from baseline) and the most homogeneous microtopography (Z = 0.0826 mm). A 10-min post-curing cycle is the optimal threshold for maximizing mechanical resilience and minimizing volatile-induced mass loss in standard 3D-printed resins. Full article

In response to the need for a simple, non-destructive method for evaluating avocado ripeness, we measured chlorophyll-related fluorescence and chromaticity of the outer skin using simple optical equipment and evaluated their relationship with whole-fruit compression (wfc), which was used as a firmness-based ripeness index. A compact system consisting of a blue LED excitation source and a small spectrometer was used to measure fluorescence spectra, and a commercially available colorimeter was used to evaluate chromaticity. Hass avocado samples purchased from multiple retail stores in Japan and stored for different periods were examined. The combination of the fluorescence intensity ratio I₇₄₀/I₆₈₅ and the lightness parameter L* showed a moderate correlation with wfc, with R² = 0.48. The fluorescence ratio I₇₄₀/I₆₈₅ was treated not as a direct measure of chlorophyll content, but as a spectral index associated with ripening-related changes in avocado skin, including chlorophyll-related fluorescence and skin optical properties. These results suggest that the combination of simple blue LED-excited fluorescence and chromaticity measurements may be useful as a practical screening approach for roughly estimating avocado ripeness in commercially available fruit. Full article

Saimaluu-Tash I, located in a high-altitude glacial valley in Kyrgyzstan, preserves one of Central Asia’s largest and most culturally significant concentrations of rock engravings. Despite extensive archaeological research, the physical, mechanical, and chromatic properties of the sandstone substrates relevant for conservation assessment remain poorly characterized. This study integrates petrographic microscopy, scanning electron microscopy, colorimetry, and Vickers hardness testing with the digital documentation of twelve engraved blocks to evaluate weathering processes, engraving practices, and long-term preservation. The engravings are carved into arkosic sandstone with carbonate cement, characterized by a weathered surface enriched in clay minerals and covered by a dark surface coating (patina). Weathered surfaces exhibit significantly lower hardness (0.6 ± 0.2 GPa) than unweathered stone (2.8 ± 0.6 GPa), which facilitated the engraving of the petroglyphs by allowing tools to penetrate more deeply into the stone. Colorimetric analyses reveal a strong chromatic contrast between the surface patina and the lighter sandstone exposed by engraving (ΔE ≈ 22.7). This contrast would have enhanced the original visibility of the petroglyphs and highlights potential conservation issues associated with the progressive reformation of this surface layer. Iconographic analysis identifies recurrent themes related to hunting, herding, mobility, animal management, and symbolic spatial practices within a nomadic high-mountain landscape. Overall, the results demonstrate how an integrated material and interpretative approach contributes to understanding rock art production processes. They support preventive and sustainable conservation strategies for vulnerable engraving landscapes shaped by long-term interactions between geological processes and human activity. Full article