Search Results (589)

In the era of global energy transition, the development of third-generation photovoltaic technologies, such as dye-sensitized solar cells, has emerged as a paramount challenge in materials engineering. This study is dedicated to the synthesis and implementation of graphene quantum dots as eco-friendly sensitizers within DSSC architectures. The GQDs were synthesized via a microwave-assisted hydrothermal route using biodegradable organic precursors, providing a “green” alternative to conventional, toxic heavy-metal-based materials. The nanocrystalline structure and optoelectronic properties of the sensitizer were verified through UV-Vis and visual photoluminescence assessment. A focal point of this research was the optimization of the GQD concentration on the mesoporous surface of the titanium dioxide photoanode. Measurements were conducted utilizing a custom-designed experimental setup integrated with 3D-printed (FDM) components and an Arduino microcontroller, ensuring precise data acquisition under controlled illumination conditions (405–625 nm). The results indicated an optimal operational point at a fivefold dilution of the stock solution (0.4 g/dm³), which yielded the highest open-circuit voltage ($V_{\mathrm{oc}}$) of 545.4 mV under UV irradiation. The decline in photovoltaic performance observed at higher concentrations was attributed to excessive nanostructure agglomeration, which effectively blocked the mesopores of the semiconductor. Furthermore, the demonstrated high chemical capacitance of the system imparts electrochemical capacitor-like characteristics to the cell, enabling energy stabilization under fluctuating illumination. To elucidate the underlying sensitization mechanisms at the atomic level, computational simulations were conducted utilizing the MACE machine-learning potential and the GFN2-xTB semi-empirical method. The theoretical models revealed that the formation of stable covalent Ti–O–C bridges (chemisorption) is imperative for establishing strong interfacial electronic coupling. Solvation models and molecular dynamics (MD) at 300 K confirmed the thermodynamic and operational robustness of the hybrid system in an aqueous electrolyte. Ultimately, this combined experimental and theoretical work conclusively demonstrates that graphene quantum dots represent an efficient, highly stable, and non-toxic alternative to classic molecular dye sensitizers. Full article

Background/Objectives: This study aimed to investigate the effect of UVC irradiation on the adhesive strength between a CAD/CAM composite resin block and dentin and to apply UVC to dental care. Methods: CAD/CAM composite resin blocks were sectioned, polished, and primed using a ceramic primer. Bovine dentin specimens were prepared and irradiated with 222 nm UVC light for no time (control, no UV), 600 s or 1200 s. After irradiation, dentin surfaces were conditioned with a tooth primer before bonding with a resin cement. Microtensile bond strength (μTBS) testing, scanning electron microscope (SEM)-based failure mode analysis, and contact angle measurements were conducted. Results: The control measured 34.32 (±3.11) MPa, the 600 s group measured 42.64 (±4.50) MPa, and the 1200 s group measured 39.75 (±7.52) MPa. There were no significant differences observed in the 1200 s group when compared with the control group. Conversely, a remarkable increase in adhesive strength was observed in the 600 s group in comparison to the control group. Failure mode analysis revealed a predominance of mixed failures in the 600 s group, which suggests enhanced interfacial bonding. Contact angle measurements demonstrated significantly enhanced surface wettability in both UVC irradiation groups relative to the control (p < 0.05). Conclusions: Photofunctionalization with 222 nm UVC improved dentin adhesion to CAD/CAM resin blocks, likely through enhanced hydrophilicity and removal of organic contaminants. Nonetheless, extended irradiation did not produce additional benefits, indicating a time-dependent response. Although 222 nm UVC irradiation demonstrates promise as a pretreatment approach in adhesive dentistry, further optimization is necessary to shorten irradiation duration and improve clinical feasibility. Full article

Ultraviolet (UV) radiation is a major environmental factor contributing to photoaging, oxidative stress, inflammation, DNA damage, and photocarcinogenesis. Conventional UV filters, although widely used in sunscreen formulations, are associated with limitations including photoinstability, photocatalytic ROS generation, potential toxicity, and environmental concerns. In recent years, plant-mediated nanomaterials have emerged as promising multifunctional photoprotective systems, combining UV attenuation with antioxidant, anti-inflammatory, and biologically adaptive properties. Plant extracts are increasingly used as reducing and stabilising agents in the green synthesis of metal and metal oxide nanoparticles. Among these, ZnO and TiO₂ serve as established inorganic UV filters, whereas Ag and Au nanoparticles have primarily been investigated for their antioxidant, anti-inflammatory, antimicrobial, and ROS-modulating properties, which may indirectly enhance photoprotection. In parallel, plant-derived organic nanoparticles and herbal nanocomposites have demonstrated enhanced biocompatibility and multifunctional performance. This review critically examines the current landscape of plant-mediated photoprotective nanomaterials, focusing on the mechanistic interplay among optical UV attenuation, reactive oxygen species (ROS) modulation, and cellular signalling regulation. Particular emphasis is placed on structure–function relationships governing nanoparticle size, surface chemistry, bandgap properties, antioxidant behaviour, and biological interactions. The review further discusses translational challenges, including reproducibility, standardisation, scalability, long-term safety, regulatory classification, and limitations in benchmarking. Importantly, current evidence suggests that no single material system simultaneously optimises UV-blocking efficiency, ROS control, biocompatibility, and industrial scalability, highlighting the need for multifunctional hybrid design strategies. Finally, future perspectives involving predictive nanoengineering, computational modelling, machine learning-guided optimisation, and adaptive photoprotective systems are discussed as emerging directions for next-generation sustainable photoprotective technologies. Full article

In recent years, multifunctional composite nanoparticles have garnered substantial attention across multiple fields, from medicine to environmental science and the food industry, owing to their superior physicochemical properties. The synching of Ni nanoparticles by chemical reduction with nickel chloride as the source, and Fe₃O₄ nanoparticles by the co-precipitation method, with Fe²⁺ and Fe³⁺ as salts, is the focus of this study. Silane was used for the surface modification of Fe₃O₄ nanoparticles, while sulfuric acid was used to modify the SMCNT. A composite in PVDF based on the blend of Ni and modified Fe₃O₄/single-walled carbon tube (SWCNT) was used as an additive. Moreover, thermoplastic polyurethane (TPU) was hot-pressed over the film to improve flexibility. To examine and characterize the nanoparticles and composite films, we used X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive spectroscopy (EDS). The results verified that the films and nanoparticles were well formed. For a deeper characterization, UV-visible spectroscopy and EMI shielding experiments were conducted for the composite films. The composite films exhibited excellent UV-blocking performance (99.9%) and a total shielding effectiveness (SET) of 13.78 dB in the Ku-band (12–18 GHz) for a thickness of 1 mm. The reflection and absorption mechanisms yield shielding performance through the synergy between conducting (Ni, SWCNT) and magnetic (Fe₃O₄) components. These results reveal that the TPU-coated composite film is a promising candidate for multifunctional UV and electromagnetic shielding. Full article

Nanostructured copper oxide (CuO) holds significant promise for optoelectronic, photocatalytic, and biomedical applications, yet its performance is critically dictated by its morphology, crystallite size, and surface chemistry. In this work, pure monoclinic CuO nanoparticles were successfully synthesized via a facile, kinetically controlled aqueous co-precipitation route using three distinct precursor salts: copper acetate (CO-Ac), copper sulfate (CO-S), and copper chloride (CO-Cl). To achieve precise architectural control, the synthesis was conducted near the thermodynamic solubility limit of the precursors combined with an abrupt NaOH injection, effectively decoupling the nucleation stage from crystal growth. Rietveld refinement of X-ray diffraction (XRD) data confirmed the structural integrity of the monoclinic lattice across all samples, χ² = 1.04 − 2.02, crystallinity 53–55%, while demonstrating that the precursor anion strongly governs the volume-averaged crystallite size, which expanded from 16 nm (CO-Ac) to 30 nm (CO-S) and 52 nm (CO-Cl). Morphological analyses revealed that acetate acts as a non-specific capping ligand, promoting isotropic, quasi-spherical nanoparticles that aggregate into high-surface-area (69.04 m²/g) “bead-chain” assemblies. Conversely, sulfate and chloride ions act as shape-directing agents via facet-selective adsorption on nucleation seeds, yielding two-dimensional plates and anisotropic acicular/needle-like architectures, respectively. X-ray photoelectron spectroscopy (XPS) and modified Auger parameter (α ~1851 eV) analyses confirmed the absolute dominance of Cu²⁺ states, with a minor fraction (~2.5 mol %) of lower-coordinated surface edge states. XPS further unveiled that the strongly alkaline environment (pH ~14) drives precursor-dependent surface chemistry: CO-Ac nanoparticles retain a clean, hydroxylated layer with minor acetate residues, whereas CO-S and CO-Cl samples develop a passive copper hydroxycarbonate (Cu₂(OH)₂CO₃) surface barrier that blocks active sites and reduces porosity. Optical properties analyzed via UV-vis diffuse reflectance revealed a pronounced, size-dependent blueshift relative to bulk CuO, with fundamental indirectly allowed bandgaps of 2.6 eV, 2.36 eV and 1.93 eV for CO-Ac, CO-S and CO-Cl samples, while the direct bandgaps shifted from 3.0 eV, 3.2 eV, and 3.57 eV for the mentioned samples. This behavior is attributed to quantum confinement governed by fine individual nanocrystals. These findings establish that precursor engineering offers a robust pathway to tailor the morphological, optical, and interfacial properties of CuO nanostructures for targeted functional devices. Full article

This study presents a photocatalytic infiltration pavement block designed to combine roadside NO_x removal with rainwater capture and temporary storage. TiO₂ and styrene–butadiene rubber (SBR) latex were incorporated into the pavement block to provide photocatalytic functionality, and direct infiltration holes were introduced to capture surface runoff, enable temporary storage, and promote delayed subgrade drainage. The effects of TiO₂ and SBR latex on compressive strength and NO_x removal were evaluated, while rainwater infiltration performance was examined using acrylic panels with different hole diameters, hole-area ratios, slopes, and V-groove treatments. The use of SBR latex improved the compressive strength of TiO₂-containing mixtures, with T10-L5 showing an 8.1% increase compared with the corresponding non-latex mixture. The same mixture achieved the highest NO_x removal efficiency, reaching 73.0% after 60 min of UV exposure. In the infiltration test, the 5 mm hole configuration gave the most stable runoff reduction, and lattice-type V-grooves improved water capture by connecting adjacent holes and guiding surface flow. A field-scale trial installation confirmed that the integrated infiltration–retention system suppressed visible ponding and runoff, provided delayed subgrade drainage, and maintained pavement stability under vehicle loading. The findings indicate that the proposed block system can provide combined air-purification and stormwater-control functions. Full article

Doping provides an effective means to tailor the chemical properties of clusters and construct novel functional materials. However, the specific effects of rare-earth doping on the structural evolution and electronic properties of semiconductor clusters remain unclear. To address this, we systematically investigated the structures, growth patterns, electronic properties, and spectroscopic characteristics of Ge_n⁻ and LaGe_n^0/− clusters (n = 10–20) using the ABCluster global search method combined with the mPW2PLYP double-hybrid density functional. Notably, the global minimum (GM) structures of Ge_n⁻ (n = 12–20), confirmed based on calculated energies and measured photoelectron spectroscopy data, differ from previously reported structures. Starting from n = 12, the GM structure of the Ge_n⁻ cluster can be considered as formed by attaching an additional Ge_(n–9) or Ge_(n–10) subcluster to a capped tetragonal antiprism Ge₉ (or dicapped tetragonal antiprism Ge₁₀) subunit. The evolution pattern of LaGe_n (n = 10–19) clusters can be viewed as substitutional structures, in which a La atom substitutes one Ge atom in the Ge_(n+1)⁻ cluster. At n = 20, a cage-like structure is formed. For LaGe_n⁻ (n = 10–19), when n = 10–12 and 18, the structures are linked configurations, where the La atom connects two Ge subclusters. For the remaining clusters, although their global minimum structures tend toward linked configurations, they are fundamentally substitutional in nature. The GM structure of LaGe₂₀⁻ is an encapsulated configuration, with the La atom encapsulated at the center of the Ge cage. The average binding energies, relative stabilities, and HOMO–LUMO energy gaps of the clusters were evaluated. The photoelectron spectra of LaGe_n⁻ (n = 10–20) and the UV–vis absorption spectrum of the LaGe₂₀⁻ cluster were simulated. The results demonstrate that the LaGe₂₀⁻ superatom cluster with high Ih symmetry exhibits favorable optical properties, along with excellent chemical and thermodynamic stability, suggesting its potential as a promising building block for further exploration in optoelectronic-related applications. Full article

Seaweeds are valuable marine resources rich in polysaccharides and polyphenols. Carbon dots (CDs) from Gracilaria salicornia (GS-CDs), Halymenia dilatata (HD-CDs), Sargasum polycystum (SP-CDs), Spatoglossum asperum (SA-CDs), Ulva lactuca (UL-CDs), and Caulerpa peltata (CP-CDs) were synthesized by a hydrothermal process and characterized by FTIR, XPS, and SEM-EDX. All the CDs had sizes less than 10 nm with spherical morphology and various functional groups. UL-CDs showed the strongest UV-A blocking efficacy via the measurement of light transmission (p < 0.05). HD-CDs exhibited the highest DPPH-RS-A (148.32 ± 1.51 μmol TE/L) and FRA-P (717.24 ± 7.87 μmol TE/L), whereas SA-CDs had the highest ABTS-RS-A (1043.40 ± 3.00 μmol TE/L). HD-CDs had antifungal activity against both Aspergillus flavus and Aspergillus parasiticus. All CDs suppressed the proliferation of both pathogenic and spoilage bacteria; however, high MIC values indicated the limited antibacterial effectiveness. CDs up to 500 mg/L maintained cell viability greater than 80% towards normal BJ cells. When SA-CDs (500 ppm) were incorporated into peeled and deveined Pacific white shrimp (Litopenaeus vannamei), lipid peroxidation during 10 days of refrigerated storage was retarded, as evidenced by lower PV, TBARS, and greater PUFA retention than the control and ascorbic acid-treated samples. Heat map and PCA analyses revealed that lipid oxidation was governed by CD type and storage time. Full article

First detected in environmental matrices in the early 2010s, UV-328 has aroused widespread concern due to its toxic risks to terrestrial vascular plants. However, its impacts on photosynthetic performance of bryophytes remain unclear. In this study, we exposed the moss Niphotrichum japonicum to a range of UV-328 concentrations and examined its morphological changes, oxidative stress, photosynthetic pigments, chlorophyll fluorescence kinetics, and energy allocation. Our results show that UV-328 caused dose-dependent leaf yellowing, surface shrinkage, and papillae collapse. It degraded photosynthetic pigments, disrupted chlorophyll a/b balance, and induced excess reactive oxygen accumulation. Chlorophyll fluorescence data indicated that UV-328 noticeably lowered Fv/Fm, Y(II), and qP. OJIP kinetics confirmed multi-target damage to the photosynthetic chain, including disruption of the oxygen evolving complex, decline of PSII energetic grouping, blockage of electron transfer from QA⁻ to QB, inhibition of plastoquinone pool turnover, and PSI terminal electron transport. Energy flux parameters pointed to fewer active PSII reaction centers and a higher light-harvesting load on each remaining center, which uncoupled light capture from electron transfer. The concentration that caused clear photosynthetic damage fell between 100 and 150 μM. In conclusion, UV-328 impacts moss photosynthesis through oxidative stress, structural damage, blocked electron transport, and energy imbalance. Full article

Melanin is a natural biopolymer with broad biological activities, yet research on melanin from the medicinal fungus Ophiocordyceps sinensis remains insufficient. In this study, two melanin fractions, TZ-a and TZ-b, were isolated from its fermentation products and characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA) and Ultraviolet–Visible spectra (UV-Vis). Their protective effects against UVB-induced damage in keratinocytes and heavy metal (Cd²⁺, Pb²⁺, As³⁺, Hg²⁺) cytotoxicity were evaluated. Both fractions exhibited characteristic melanin peaks but showed structural differences. TZ-a displayed lamellar or needle-like crystals, whereas TZ-b formed block-like aggregates. Both demonstrated good thermal stability. UV-Vis spectra confirmed their typical melanin identity. At 200 μg/mL, TZ-a and TZ-b increased cell viability from ~50% (model) to 80.59% and 82.48%, respectively. Additionally, they elevated the proportion of viable cells within the apoptotic population from 59.11% to 86.08% and 84.79%. Both fractions concentration-dependently alleviated heavy metal-induced cytotoxicity, reduced malondialdehyde levels, and restored glutathione pools. In conclusion, the melanin fractions TZ-a and TZ-b from O. sinensis exhibited photoprotective effects and alleviated heavy metal toxicity. Full article

Natural antioxidants are limited in food packaging due to poor stability and compatibility. A multifunctional film was successfully prepared via the incorporation of functional fillers into a guar gum/polyvinyl alcohol (GP) matrix. ZIF-8 was amino-functionalized to enhance rutin (Rt) loading, and the resulting ZIF-8-NH₂@Rt was combined with purple sweet potato anthocyanins (PSPA) to fabricate a composite film for pork freshness monitoring. Compared with neat GP, the ZIF-8-NH₂@Rt/PSPA/GP film showed a 30.6% increase in tensile strength and an elongation at break of 36.6%. The composite film also imparted exceptional UV-blocking capabilities, with light transmittance plummeting to 3.22% in the UVA region, 0.40% in the UVB region, and 47.53% within the visible light spectrum. The films displayed significant antioxidant properties, with DPPH and ABTS scavenging activities recorded at 73.27% and 67.64%, respectively. During pork storage, the film exhibited stable color changes. The G/R values corresponding to the limit of edibility were determined to be 0.78 and 0.67 for storage at 25 °C and 4 °C, respectively. The film was reusable for four cycles and extended the shelf life of pork by at least one day. These findings highlight the film’s considerable promise in the realm of smart food packaging and dynamic freshness tracing. Full article

The growing demand for durable and environmentally sustainable bioactive textiles has created a need for functionalization strategies that minimize the release of active agents during use and laundering. In this study, a novel chloroxylenol-functionalized vinyl sulfone reactive dye was synthesized through the coupling of chloroxylenol with diazotized para-ester and characterized using FTIR, UV–Vis, ¹H-NMR, and ¹³C-NMR spectroscopy. The synthesized dye was applied to cotton fabric through an exhaust dyeing process, enabling simultaneous coloration and biofunctionalization in a single step. The dye exhibited high substantivity toward cotton, achieving dye exhaustion and fixation values of 95% and 91%, respectively. The dyed fabric demonstrated excellent antibacterial activity against Staphylococcus aureus (99.99%) and Escherichia coli (94%), antiviral activity of 87%, and antifungal activity of 86% before laundering. After 20 laundering cycles, antibacterial activity remained at 96% against S. aureus and 91% against E. coli, while antiviral and antifungal activities remained at 83% and 82%, respectively, confirming the durability of the bioactive functionality. Optical density measurements further verified substantial bacterial growth inhibition, whereas MTT assays using L929 fibroblasts demonstrated acceptable biocompatibility with cell viability exceeding 80% at the highest tested concentration. The dyed fabrics also exhibited excellent ultraviolet protection (UPF 119) with UVA and UVB blocking efficiencies of 99.35% and 98.98%, respectively, together with good colorfastness properties. Furthermore, UV–Vis analysis of the washing liquor indicated negligible dye release under the investigated laundering conditions. These findings demonstrate an effective and sustainable one-step strategy for producing durable multifunctional bioactive textiles while reducing processing steps and minimizing the potential release of active agents during use. Full article

This study establishes a unified electrochemical–optical framework to elucidate adsorption-controlled charge transfer and electronic excitation at platinum–electrolyte interfaces modified by biomolecules and metal nanoparticles. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and UV-Vis absorption spectroscopy with Tauc analysis were used to probe transformations induced by vitamin B6 (pyridoxine) and silver nanoparticles (nAg) in Na₂SO₄ aqueous electrolytes. In the supporting electrolyte, platinum behaves as a blocking capacitive interface with nearly symmetric anodic–cathodic charges, high charge-transfer resistance (R_ct ≈ 3.14 kΩ·cm²), low double-layer capacitance (C_dl ≈ 4.0 × 10⁻⁵ F·cm⁻²), and deep-UV transitions (E_low ≥ 3.8 eV), confirming the electrochemical inertness of sulfate media. Vitamin B6 molecules interact with the electrode surface and modify the structure of the electrical double layer at the platinum/electrolyte interface, restructuring the double layer, increasing C_dl (≈1.2 × 10⁻⁴ F·cm⁻²), decreasing R_ct (≈0.23 kΩ·cm²), and generating irreversible surface-confined anodic processes. Tauc plots yield two transitions (E_low ≈ 2.9 eV; E_high ≈ 4.1 eV), attributed to molecular states and weak charge-transfer interactions. The results suggest electronic interactions between the silver nanoparticles and the adsorbed vitamin B6 molecules at the electrode interface. Strong electronic interactions between vitamin B6 and nAg yields ultralow R_ct (≈58 Ω·cm²), enhanced pseudocapacitance (C_dl ≈ 2.9 × 10⁻⁴ F·cm⁻²), and red-shifted transitions (E_low ≈ 2.2 eV; E_high ≈ 3.7 eV). These results show that adsorption-induced electronic coupling governs interfacial kinetics and optical excitation pathways. Full article

In this work, the structural, optical, vibrational, and stability properties of a series of Al_xAs_x nanostructures are systematically investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Starting from the fundamental cubic-like Al₄As₄ building block, progressively larger nanostructures were constructed through directional elongation and structural rearrangements, allowing for the exploration of one-dimensional chains, two-dimensional planar structures, and several exotic geometries. The calculated UV–visible absorption spectra reveal that structural dimensionality and topology strongly influence the electronic transitions of the nanostructures, with elongated and distorted configurations exhibiting broader absorption features and richer spectral distribution. Vibrational analysis shows that increasing structural complexity and reducing symmetry lead to a higher density of IR-active modes and more complex infrared spectra. The stability of the nanostructures is evaluated through binding energy calculations, which indicate a clear size-dependent stabilization trend, with the Al₂₄As₂₄-L1 configuration exhibiting the highest stability among the examined systems. In addition, the calculated HOMO-LUMO gaps reveal the semiconducting character of the clusters and demonstrate their sensitivity to geometric topology. The present results establish clear structure–property relationships between dimensional growth and the optical response of AlAs nanoparticles and provide theoretical reference data for future experimental investigations of III-V semiconductor nanostructures. Full article

The long-term stability of biodegradable polymer coatings deposited by matrix-assisted pulsed laser evaporation (MAPLE) remains insufficiently understood, particularly under ultraviolet irradiation conditions where photochemical effects may accompany material transfer. In this work, thin films of poly(lactide-co-caprolactone)-block-poly(ethyleneglycol)-block-poly(lactide-co-caprolactone), also known as PLCL-PEG-PLCL, are deposited from chloroform solutions by UV-MAPLE using a nanosecond Nd:YAG laser operating at 266 nm over a wide laser fluence range (0.25–0.9 J/cm²). The effect of laser fluence on the morphological, structural, and chemical evolution of the coatings is investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), focused ion beam scanning electron microscopy (FIB-SEM), and X-ray diffraction (XRD). At low laser fluence, relatively homogeneous coatings are obtained while largely preserving the characteristic functional groups of the triblock copolymer. Increasing the laser fluence progressively induces surface restructuring phenomena, including droplets, wrinkles, and the appearance of highly symmetric faceted structures. These entities develop preferentially in samples deposited at elevated fluence and frequently appear only after prolonged aging under ambient conditions, revealing delayed recrystallization behaviour associated with metastable species generated during the deposition process. EDS analyses reveal localized chlorine enrichment within the faceted structures, while FIB-SEM investigations show porous internal morphologies. XRD confirms that the polymer matrix remains predominantly amorphous. The combined observations suggest that UV-MAPLE deposition from chloroform involves not only physical material transfer but also photochemical processes that promote decomposition, recombination, and delayed crystallization phenomena. A phenomenological model describing the successive stages of surface evolution, aging, and recrystallization is proposed. These results provide new insight into the long-term evolution of laser-deposited biodegradable polymer coatings and highlight the importance of solvent selection and processing conditions in determining their stability. Full article