Search Results (93)

This study investigates the composition, morphology and cultural significance of red pigment traces identified on bone pointed tools discovered in the Chalcolithic tell settlement of Pietrele–Măgura Gorgana, attributed to the Kodjadermen–Gumelnița–Karanovo VI cultural complex (4600–4250 BC). The observed use-wear patterns are consistent with repeated contact with soft, non-abrasive materials, including hide working, pigment application on leather or other organic surfaces, fiber manipulation, and perforation of soft substrates. Use-wear analysis revealed polished and flattened distal ends, compatible with repeated use on soft, non-abrasive materials, such as hide, leather, fiber, or other organic substrates. The possibility of pigment application directly on skin, in a practice analogous to tattooing, as previously published, cannot be excluded but remains speculative in the absence of experimental reference data or residue evidence specifically linked to such use. An associated ceramic container was tentatively interpreted as a possible vessel for ochre preparation, suggesting local processing of the pigment. The artifacts were investigated using multi-analytical archaeometric methods: SEM-EDS, AFM, TEM, FTIR, Raman, TGA, CLSM and pseudo-color image segmentation and 3D rendering of porosity distribution. The results consistently identified an iron oxide-based pigment, dominated by hematite and/or goethite, specific to ochre. Pigment particles (50–300 nm) form a well-defined superficial layer on the bone substrate, without Fe–Ca reactions at the interface. The simultaneous presence of Ca, P, Si, Mg and K indicates a silicate matrix with an apatite component, compatible with local and poorly purified raw materials. CIELAB colorimetric analyses revealed significant chromatic variability, suggesting the use of hematite-rich pigments and possible thermal transformations of goethite. The results contribute to the understanding of the pigment technologies of the Chalcolithic communities of the Lower Danube. Full article

While convolutional neural networks (CNNs) excel at image classification, their generalization across domains and robustness to nonlinear degradation remain challenges in art media classification (AMC). To address these challenges, this article presents a dual-stage analytical framework: first, an evaluation of seven discrete CNN architectures—ranging from VGG16 to ConvNeXt—subjected to domain shift using the New Spain (Mexico) Art Media Dataset; and second, a formal robustness analysis using an artistic corruption benchmark (Art-C). This benchmark simulates nonlinear degradations, including cracking, oxidized varnish, and pictorial abstraction. Our results demonstrate that while deep convolutional representations maintain acceptable transferability (accuracy $>70\%$), significant variability exists in architectural stability (mean 0.0607) under progressive stochastic degradation. Notably, Xception exhibited the highest robustness (Art-mCE = 0.8039), whereas VGG16 showed the greatest relative performance decay. Severity analysis further indicates that structural perturbations induce higher error rates than chromatic shifts, suggesting that CNNs are more sensitive to topological features (depth and residual connections) than color-space distributions. We provide quantitative evidence characterizing the relationship between architectural topology and empirical stability in non-natural image domains. Full article

Wine bottle aging is governed by complex redox reactions involving phenolic compounds, oxygen transfer and storage conditions, which collectively determine the evolution of wine composition and sensory properties. This review critically examines the main oxidative mechanisms responsible for bottle aging and evaluates traditional and emerging strategies aimed at modulating the evolution of wine. Particular attention is paid to oxygen management, cork type, temperature and light exposure, as well as alternative approaches such as accelerated aging techniques and underwater storage. The available evidence suggests that most accelerated aging technologies fail to replicate the chemical pathways of natural in-bottle aging, often resulting in different aromatic profiles. Attention is paid to underwater aging, an emerging practice that combines specific conditions of temperature, light and limited oxygen availability. The results of the available studies indicate that underwater aging does not significantly alter the basic chemical parameters of wine, but can modulate its phenolic, chromatic and sensory evolution, suggesting a slowdown in oxidative processes compared to traditional aging in the cellar. Full article

The storage quality of fresh-cut peach fruit is compromised by weight loss and chromatic aberration. In this experiment, taurine at 30 mg L⁻¹ was applied to fresh-cut peaches to evaluate its effect on storage quality. Changes in weight loss, chromatic aberration, antioxidant system, endogenous nitric oxide (NO) metabolism, endogenous hydrogen sulfide (H₂S) metabolism, and phenylpropanoid metabolism were studied. The results indicated that 30 mg L⁻¹ taurine effectively improved the ability to scavenge ROS, including •OH, O₂^•−, MDA, and H₂O₂, by inhibiting the decrease in the activities of SOD and CAT, enhancing POD activity, reducing PPO activity, and maintaining the AsA-GSH cycle. Moreover, taurine treatment increased the activities of 4CL and PAL and retarded the decrease in the activities of SKDH and C4H, thereby improving the accumulation of total phenols, flavonoids, and lignin. These findings showed that taurine mitigated oxidative damage in fresh-cut peaches by enhancing the antioxidant defense system. Exogenous taurine consistently enhanced NOS-like activity while decreasing NR activity in the early storage phase, and elevated the contents of L-Arginine, nitrite, and endogenous NO. Taurine treatment up-regulated the activities of SAT, L-CD, and OAS-TL, thus promoting endogenous H₂S content in fresh-cut peaches. Taurine alleviated weight loss and chromatic aberration in fresh-cut peaches during storage by enhancing the antioxidant system and modulating NO, H₂S and phenylpropanoid metabolism. Full article

Heterogeneous catalytic degradation of organic dyes can effectively achieve the goals of reducing the chromaticity of aqueous solutions and completely removing pollutants. We here present a carbon-nitride-wrapped zero-valent Fe catalyst (CNFe), which can directly degrade Acid Red G (ARG) dye without additional oxidants. CNFe exhibited a nanotube-like morphology, wherein the zero-valent Fe (Fe⁰) was wrapped by a carbon layer to effectively enhance its dispersibility and prevent its oxidative deactivation. Meanwhile, the large specific surface area (169.19 m²/g), along with abundant active sites such as Fe and O, endowed CNFe with excellent activity. Under strongly acidic conditions, even in the presence of various anions, CNFe can still remove approximately 91.6% of ARG within 30 min. In a 10 h continuous flow column experiment, the removal efficiency of ARG consistently exceeded 67.6%, indicating that CNFe had great potential for treating actual dyeing wastewater. Catalytic mechanism studies showed that, under neutral conditions, CNFe mainly removed ARG through adsorption, whereas, under acidic conditions, the Fe⁰ in CNFe can not only activate molecular oxygen to generate HO· for the oxidative degradation of ARG but also remove ARG via reduction. Furthermore, CNFe can adsorb ARG through hydrogen bonding of surface hydroxyl groups. The developmental toxicity of the generated intermediates was effectively reduced, demonstrating lower environmental risks. Therefore, this study provided a simple, high-efficiency, and economical method for removing dyes from water, which can offer guidance for the treatment of practical dye wastewater. Full article

Zn-Fe-Cr coatings were successfully deposited on sintered Nd-Fe-B matrix through the addition of the complexing agent etidronic acid (HEDP) to the plating solution; the electrodeposited process of the metal elements and the corrosion behavior of the coatings were also investigated. Through cyclic voltammetry (CV) tests, it was observed that the reduction potential difference between the metal elements was reduced by the addition of HEDP, which contributed to a more feasible electrodeposited process. The surface of Zn-Fe-Cr coating was covered by a chromate conversion film, and its microstructure was identified as the solid solution of Fe and Cr in Zn matrix. Compared with Zn and Zn-Fe coatings, the corrosion current density (J_corr) of Zn-Fe-Cr coating was decreased to 0.28 × 10⁻⁶ A·cm⁻², and the corrosion potential (E_corr) was increased to −1.01 V. Compared with the Zn and Zn-Fe coatings, the corrosion rate of the Zn-Fe-Cr coating has decreased by 90% and 98%, respectively. The corrosion resistance of coatings was further analyzed by neutral salt spray tests (NSS), and the analysis results showed that a composite oxide layer, composed of ZnO and Cr₂O₃, was formed in the corroded area of Zn-Fe-Cr coating during the corrosion process, which is capable of effectively inhibiting the expansion of the corrosion area. This research provides a promising strategy for ensuring the long-term service integrity of sintered Nd-Fe-B materials in marine environments. Full article

High-resolution long-wave infrared imaging is critical for lunar mineralogy. However, it must balance a large FOV, a small F-number, chromatic aberration correction, optical efficiency, and system compactness. We introduce a push-broom multispectral imager employing a collaborative integrated filter array and an off-axis two-mirror Gregorian telescope. The system, utilizing an uncooled Vanadium Oxide detector, has an F-number of 1.0, an IFOV of 0.04943 mrad, and a 2.90° × 2.83° FOV that covers eight bands ranging between 7.38 and 14.3 μm. Optical simulation confirms that the modulation transfer function exceeds 0.25 at the Nyquist frequency of 42 lp/mm, with a maximum RMS spot radius of less than 12 μm. The system has remarkable versatility within an operating temperature range of 0 °C to 40 °C. Thermal background radiation analysis, stray light analysis, and detection sensitivity were conducted, which indicated that the system has good compliance with indicators and engineering feasibility. This high-throughput optical design meets the rigorous criteria for lunar remote sensing and provides a reliable device for site evaluation in future manned lunar missions. Full article

This paper reports initial experimental results related to the preparation of colored anodic titania thin layers using various deep eutectic solvent (DES)-based formulations. Electrolytes based on choline dihydrogen citrate–oxalic acid–ethylene glycol (1:1:1 molar ratio), choline chloride–oxalic acid (1:1 molar ratio) and choline chloride–lactic acid (1:2 molar ratio) eutectic mixtures were investigated. The anodization has been performed at constant voltage in a range of 10–100 V for various periods of time between 1 and 5 min at room temperature under mild stirring. A brief description of anodization procedures, as well as of some characteristics, from appearance and morphological viewpoints, is presented. A quantitative analysis of color characteristics in relation to the DES-based electrolyte and applied voltage using the CIELAB system is also discussed. The achieved chromatic scale follows this order of colors: golden—blue—light blue—light blue/green—pink—violet. This depends on the applied potential and the DES-based electrolyte. The films present a relatively high brightness and color saturation. The hue vs. anodization voltage diagrams suggest an almost linear dependence of the oxide growth measured against the applied voltage. The corrosion performance has been assessed through continuous immersion tests in (i) 0.5 M NaCl for 240 h and (ii) Hank’s biological solution for 96 h with intermediate visual examinations and recording corrosion potential, as well as potentiodynamic polarization curves and impedance spectra at open circuit potential. Different corrosion performances are discussed considering the aggressive medium involved and the used DES-based systems. Full article

The management of invasive alien species (IAS) generates large amounts of plant waste biomass that is commonly disposed of by burning or destruction, leading to environmental and economic drawbacks. At the same time, the production of synthetic dyes and pigments used in printing and graphic applications remains a significant source of pollution. In this context, the valorization of IAS biomass as a source of natural colorants represents a sustainable alternative aligned with circular economy principles. Here, biocompounds and natural dyes were extracted from four invasive or non-native plant species—Arundo donax, Phytolacca americana, Tradescantia fluminensis, and Eucalyptus globulus—using five solid–liquid extraction methods: infusion, infusion with heat, thermal agitation, Soxhlet extraction, and ultrasonic-assisted extraction. Extraction efficiency and color preservation were comparatively evaluated. Although Soxhlet extraction provided the highest extraction yield (up to 30.5%), infusion with heat proved to be the most suitable method for preserving color integrity and minimizing oxidation. Liquid dyes obtained by the selected extraction method were converted into solid pigments through a lake pigment precipitation process using aluminum potassium sulfate and sodium bicarbonate. The resulting pigments were characterized in terms of chemical composition, particle size, and chromatic properties, and subsequently formulated into oil-based inks using linseed oil as binder. Scanning electron microscopy revealed pigment particle sizes ranging from approximately 2.1 to 8.3 µm, depending on the plant source, and confirmed adequate ink penetration and distribution on commercial printmaking paper. The obtained pigments exhibited color tones ranging from yellow to brown and grey, mainly associated with the phenolic and tannin content of the original biomass. Printing tests demonstrated the suitability of the developed inks for manual printmaking techniques, highlighting the potential of IAS-derived pigments as sustainable alternatives for artistic and printing applications. Full article

ywqN encodes a protein with an unassigned function that shares partial 3D homology with B. subtilis YhdA, Pseudomonas putida ChrR, and Escherichia coli YieF, which are NADP(H)/FMN-dependent oxidoreductases that catalyze the reduction of diverse chemical pollutants, including Cr(VI). Here, we report that a recombinant His₆-YwqN protein displays marginal chromate reductase activity but is capable of reducing synthetic azo dyes. Remarkably, His₆-YwqN exhibits a potent quinone reductase activity, catalyzing the reduction of menadione (MD) and 1,4-naphthoquinone (NQ). The individual and combined roles of YwqN and YhdA in protecting B. subtilis from ROS-promoting agents were further tested. Sensitization to the oxidizing agent H₂O₂ required the simultaneous loss of both YwqN and YhdA. In contrast, strains deficient in ywqN, either alone or in combination with yhdA, exhibited similar but higher susceptibilities to the superoxide-generating agent MD compared with the WT strain. These results indicate that YwqN and YhdA contribute to protection against the deleterious effects of ROS in B. subtilis. Further results revealed that while YwqN, but not YhdA, prevented MD-induced mutagenesis, both proteins synergistically prevented Rif^R mutations induced by H₂O₂. Furthermore, overexpression of YwqN suppressed the hypermutagenesis phenotype of a B. subtilis strain deficient in the prevention/repair oxidized guanine (GO) system, which is prone to accumulate 8-oxoGs. In summary, YwqN counteracts the cytotoxic and genotoxic effects promoted by ROS in B. subtilis and represents a potential tool for the remediation of soils and effluents contaminated with carcinogenic azo dyes. Full article

Light plays a critical role in the physiology and pigmentation of aquatic animals. Regulating the light environment of aquatic animals offers insights into healthy aquaculture practices. In this study, Procambarus clarkii were reared under four different light colors—white (WL), red (RL), blue (BL), and green (GL)—for 21 days, with four replicates per light color. Morphological characteristics did not differ among light treatments. However, significant differences were observed in hemolymph cortisol levels and tyrosinase activity across different tissues (hemolymph, muscle, hepatopancreas) among groups (RL > BL > GL > WL). Hepatopancreatic CAT activity in WL was significantly higher than that in GL and BL, whereas hepatopancreatic MDA content was highest in BL. Regarding chromatic parameters, the yellow color of the RL cephalothorax cuticle and the red color of the muscle were more pronounced than in WL, The chela cuticle of GL is darker than RL, while the red color of the chela cuticle was more pronounced than in WL.. For pigment content, cephalothorax cuticle astaxanthin content in BL was significantly higher than that in other light color groups, while abdominal cuticle astaxanthin content was lowest in BL. Chela cuticle astaxanthin content in RL was significantly higher than that in WL, and chela cuticle astaxanthin and lutein contents in WL were significantly lower than those in BL and GL. Compared with WL, hepatopancreatic glutathione S-transferase P1 (GSTP1) mRNA expression significantly decreased under colored light, whereas NinaB mRNA expression significantly increased under RL and BL. These results indicate that light color does not affect the morphological characteristics of P. clarkii but significantly modulates oxidative stress responses, physiological status and energy metabolism. Different light colors may mediate carotenoid transport and deposition by regulating the expression of GSTP1, NinaB, leading to specific chromatic differences in different body parts of P. clarkii. Comprehensive analysis revealed that the red light environment exerted a more positive effect on enhancing the body color of P. clarkii. This study provides a reference for revealing the mechanism of light color regulating crustacean physiological function and pigmentation and optimizing aquaculture model. Full article

The phase-pure cubic pyrochlore of the Bi₂Cr_0.5Co_0.5Nb₂O_9+Δ composition can be successfully synthesized by a modified sol–gel method (Pecini method-PM) and a traditional solid-phase method (SPM). A feature of the solid-phase synthesis method is the formation of bismuth(VI) chromates as intermediate synthesis products, which is confirmed by X-ray spectroscopy data (NEXAFS). During the sol–gel synthesis method, bismuth chromates are not formed due to the formation of the Bi₂₈O₃₂(SO₄)₁₀ salt, which is thermally stable up to 880 °C, preventing the interaction of bismuth(III) and chromium(III) oxides. The temperature of the final pyrochlore calcination during sol–gel synthesis is reduced by 100 °C (950 °C) compared to the solid-phase method. The crystal structure of pyrochlore (sp. gr. Fd-3m, PM, a = 10.49360(5) Å, Z = 4) was refined by the Rietveld method based on X-ray powder diffraction (XRD) data. NEXAFS Cr2p and Co2p spectra of ceramics synthesized at 1050 °C correspond to the charge states of Cr(III), Co(II) and Co(III) ions. The thermal expansion coefficient of the cell was calculated from high-temperature X-ray diffraction measurements in the range of 20–1200 °C. The thermal expansion coefficient (TEC) monotonically increases from 3.92 × 10⁻⁶ °C⁻¹ (20 °C) to 9.89 × 10⁻⁶ °C⁻¹ (1020 °C). Above 1110 °C, TEC decreases due to thermal dissociation of Bi₂Cr_0.5Co_0.5Nb₂O_9+Δ with the formation of CoNb₂O₆, Bi₂O₃. The mixed pyrochlore (PM) exhibits a moderately high permittivity of ∼97, and low dielectric losses of ∼2 × 10⁻³ at 1 MHz and ∼30 °C. The activation energy of conductivity of the high-temperature region is 0.89 eV. The electrical properties of pyrochlore were synthesized by the ceramic (SPM) and Pechini methods (PM) were analyzed. The electrical properties of the samples up to 400 °C were modeled using equivalent electrical circuits Full article

Substantial improvements in the performance of optical interconnects based on multi-mode fibers are required to support emerging single-channel data transmission rates of 200 Gb/s and 400 Gb/s. Future optical components must combine very high modulation bandwidths—supporting signaling at 100 Gbaud and 200 Gbaud—with reduced spectral width to mitigate chromatic-dispersion-induced pulse broadening and increased brightness to further restrict flux-confining area in multi-mode fibers and thereby increase the effective modal bandwidth (EMB). A particularly promising route to improved performance within standard oxide-confined VCSEL technology is the introduction of multiple isolated or optically coupled oxide-confined apertures, which we refer to collectively as multi-aperture (MA) VCSEL arrays. We show that properly designed MA VCSELs exhibit narrow emission spectra, narrow far-field profiles and extended intrinsic modulation bandwidths, enabling longer-reach data transmission over both multi-mode (MMF) and single-mode fibers (SMF). One approach uses optically isolated apertures with lateral dimensions of approximately 2–3 µm arranged with a pitch of 10–12 µm or less. Such devices demonstrate relaxation oscillation frequencies of around 30 GHz in continuous-wave operation and intrinsic modulation bandwidths approaching 50 GHz. Compared with a conventional single-aperture VCSELs of equivalent oxide-confined area, MA designs can reduce the spectral width (root mean square values < 0.15 nm), lower series resistance (≈50 Ω) and limit junction overheating through more efficient multi-spot heat dissipation at the same total current. As each aperture lases in a single transverse mode, these devices exhibit narrow far-field patterns. In combination with well-defined spacing between emitting spots, they permit tailored restricted launch conditions in MMFs, enhancing effective modal bandwidth. In another MA approach, the apertures are optically coupled such that self-injection locking (SIL) leads to lasing in a single supermode. One may regard one of the supermodes as acting as a master mode controlling the other one. Streak-camera studies reveal post-pulse oscillations in the SIL regime at frequencies up to 100 GHz. MA VCSELs enable a favorable combination of wavelength chirp and chromatic dispersion, extending transmission distances over MMFs beyond those expected for zero-chirp sources and supporting transfer bandwidths up to 60 GHz over kilometer-length SMF links. Full article

Chinese lacquer (urushi), a traditional East Asian coating material, has been used for more than 7000 years due to its durability, gloss, and cultural significance. However, its long-term stability under natural light remains insufficiently studied, especially regarding the role of mineral pigments in modulating photoaging behavior. In this study, three traditional lacquer coatings pigmented with cinnabar (HgS), orpiment (As₂S₃), and lapis lazuli were subjected to natural light aging for nine weeks. Colorimetric analysis revealed rapid chromatic changes during the initial stage of exposure, followed by slower transformations, with cinnabar-based red lacquer showing superior stability compared to orpiment- and lapis-based coatings. Gloss measurements and surface roughness analyses demonstrated a strong negative correlation, with yellow lacquer exhibiting the most severe gloss loss (≈30%) and roughness increase (≈89%), consistent with scanning electron microscopy observations of microcracking and surface deterioration. Fourier-transform infrared spectroscopy (FTIR) indicated pigment-dependent oxidative degradation, characterized by intensified carbonyl and aromatic C=C bands. Collectively, the results confirm that mineral pigments strongly influence the optical, chemical, and structural stability of lacquer coatings. From a conservation perspective, cinnabar-based lacquers exhibit higher resilience, whereas orpiment- and lapis-colored coatings are highly vulnerable, underscoring the need for pigment-specific preservation strategies for lacquerware cultural heritage. Full article

CoCrFeNiMn HEA-based composites with Cr₃C₂, 15% Ag, and different mass fractions of CaF₂/BaF₂ eutectic fluoride were fabricated by spark plasma sintering. The tribological properties and wear mechanism of the composites were investigated from RT to 800 °C. The friction coefficients of CoCrFeNiMn-Cr₃C₂-Ag-CaF₂/BaF₂ composites decrease from RT to 800 °C except for 400 °C. At 800 °C, with the increasing mass fraction of the eutectic fluoride, the friction coefficient of the composite decreases from 0.53 to 0.25. The wear rates of the composite with 15% CaF₂/BaF₂ eutectic fluoride decrease significantly at high temperatures. The CoCrFeNiMn-Cr₃C₂-Ag-15%CaF₂/BaF₂ composite exhibits the lowest wear rates at 400 °C, 600 °C, and 800 °C, which are 4.47 × 10⁻⁶ mm³/N·m, 5.15 × 10⁻⁶ mm³/N·m, and 2.42 × 10⁻⁶ mm³/N·m, respectively. At low temperatures, the tribological mechanisms of the composites are micro-plowing and micro-cutting, and Ag is formed as a lubricating film to reduce the friction coefficient. At high temperature, fluorides form a transfer film on the wear scar surface, providing a lubricating effect. Also, the oxide layers and chromate are formed on the worn surfaces of the composites, which are beneficial for improving the wear resistance. Based on the mechanical properties and tribological behavior, the CoCrFeNiMn-Cr₃C₂-Ag-15%CaF₂/BaF₂ composite demonstrates the best comprehensive properties. Full article