Search Results (3,062)

Silver maple is a fast-growing, adaptable tree that often frequents wet places and thus can play an important ecological role in replanting schemes. For this, robust, high-quality seedlings are essential. In other tree species, improved seedling quality has been achieved by treating with a combination of humic substances (HSs) and bacterial strains capable of synthesizing auxin phytohormone; the benefit being attributed, without clear supporting evidence, to changes in phytohormone concentrations in the plant. To clarify the uncertainty, we conducted assays of hormones in silver maple seedlings treated with HSs and appropriate bacteria. We hypothesized that any positive additive effects between HSs and bacteria may be due to the ability of HSs to bind phytohormones. This hypothesis was tested and confirmed by using optical absorption spectra of auxins, humic acids, and their combination, as well as by modeling their interactions. The combination of humic substances and bacteria resulted in an approximately 1.5-fold increase in auxin content in roots, accompanied by a marked increase in root weight and length. We suggest this is likely the outcome of HSs binding to bacterial auxins and delivering them to plant roots. Concentrations of cytokinins and abscisic acid also changed under these treatments, which may help explain observed increases in photosynthesis and improved water balance. Full article

Reconfigurable photonic metasurfaces enable tunable thermal-emission engineering in the long-wave infrared (LWIR), particularly within the 8–13 μm atmospheric window. This work includes the investigation on a concentric-ring VO₂/SiO₂/Au metasurface for LWIR spectral-emissivity modulation. Full-wave simulations showed that, in the metallic phase (σ = 2 × 10⁵ S/m where σ is conductivity), the structure exhibited an absorption over 90% across the 9.3–15 μm sub-band, with two near-unity resonances near 10.2 and 13.3 μm. Control structures, gap-dependent spectra, E-field maps, and current-density Cartesian multipole decomposition supported a hybridized-ring mechanism in which both dominant resonances were predominantly electric-dipole-like ring branches whose spectral positions and field localizations were modified by inter-ring coupling. Across the conductivity sweep, the normal-incidence band-averaged 8–13 μm emissivity changed from 0.0184 to 0.8844, corresponding to a switching ratio of 48.06. The four-fold symmetry of unit cell also yielded polarization-insensitive and angularly robust LWIR absorption, while the simplified endpoint thermal-balance estimate indicated a metallic-state net cooling power of 49.3 W m⁻² at T = T_amb = 300 K, where T_amb was the ambient temperature, and an estimated equilibrium temperature drop of 4.4 K below the ambient for the metallic-state endpoint, whereas the insulating-state one suppressed this response. These results identify concentric VO₂ ring metasurfaces as promising candidates for switchable LWIR thermal-emission control. Full article

Wild carrot (Daucus carota subsp. carota), the wild relative of cultivated carrot, is globally identified as an invasive weed that threatens hybrid carrot seed production through natural cross-pollination, resulting in compromised genetic purity. Manual identification across the large areas required to ensure genetic purity in carrot seed crops is impractical. Remote sensing offers an alternative; however, morphological similarities among wild carrot, cultivated carrot, and common weeds hinder reliable detection. Early identification, however, remains essential for preventing genetic contamination. This study evaluated leaf-level hyperspectral reflectance spectroscopy (400–2450 nm) with machine learning to discriminate wild carrot from hybrid carrots, parental lines, and 19 co-occurring weed species. Spectral data from 266 wild carrot plants across three New Zealand sites and six weeks (5–10 weeks after emergence) showed negligible spatial effects (R² = 0.034–0.055, pseudo-F = 1.46–2.39, p > 0.05) and moderate temporal variation (R² = 0.136–0.151, pseudo-F = 5.48–6.17, p < 0.001), indicating broadly stable spectral signatures suitable for model generalization. Savitzky–Golay filtering, with min–max normalization outperformed SNV, yielding high full-spectrum accuracies for wild carrot vs. other species (90.35%, κ = 0.80), wild carrot vs. weeds (96.03%, κ = 0.92), and a multi-class model (90.79%, κ = 0.88). After removing atmospheric water-absorption bands to follow airborne sensing, reduced-band models based on airborne-compatible wavelengths maintained strong performance, including 89.40% accuracy (κ = 0.79) for wild carrot vs. weeds using a 20-band Subspace Discriminant model (400–402, 527, 705–720 nm). These findings demonstrate that stable wild carrot spectra and carefully selected visible and red-edge bands can underpin cost-effective UAV/UGV-mounted hyperspectral or multispectral sensors for site-specific wild carrot management. Full article

In this work, we extracted silk fibroin (SF) via a tertiary solvent system (CaCl₂:Ethanol:H₂O) and then blended it with chitosan (CS) solution to construct microparticles using the water-in-oil-emulsion–diffusion method. For the mixture of SF/CS solution aqueous phase (W) was prepared at ratios of 4:0, 3:1, 1:1, 1:3, and 0:4, using ethyl acetate as the oil phase (O). After the microparticles were prepared, their morphology was examined using scanning electron microscopy (SEM). The optimal preparation conditions were determined to be a 1% (w/v) aqueous phase with a volume of 1 milliliter, 100 milliliters of oil phase, and a stirring speed of 700 rpm. The average microparticle size was 50–100 micrometers. ATR−FTIR spectra showed unique functional groups of SF and CS, as well as interactions between the two polymers. The results of the thermal property study using a TGA instrument showed that SF microparticles had a higher maximum decomposition temperature (T_d,max) than chitosan, and the blended microparticles’ T_d,max increased with the proportion of SF. Most microparticles exhibited a semi-crystalline polymer structure, with SF microparticles being the most hydrophobic, followed by blended microparticles and CS, respectively. Testing for absorption capacity, the SF microparticles were more effective at absorbing used engine oil than vegetable oil and chloroform, while CS microparticles showed the highest capacity for vegetable oil. The experimental results indicated that all SF/CS blended particles played an efficiency of absorption variable by ratios of SF or CS blended. This suggested that the prepared microparticles might be useful for oil/water separation application. Full article

In this study, probe 1, a novel mitochondria-targeted fluorescent probe for the colorimetric and ratiometric detection of Hg²⁺, was developed. Upon addition of Hg²⁺ to the solution of 1, distinct spectral changes were observed. The absorption spectra underwent a blue shift from 510 nm to 450 nm (Δλ = 60 nm), and the solution color changed from red to pale yellow under daylight. Concurrently, a significant blue shift occurred from 645 nm to 540 nm (Δλ = 105 nm) in the fluorescence spectra. There were remarkable variations in the fluorescence intensity ratio of F_540nm/F_645nm with the R/R₀ value reaching up to 824-fold, and the fluorescence color changed from red to green under a 365 nm UV lamp. Probe 1 featured a large Stokes shift of 135 nm, high sensitivity with an LOD of 25.5 nM, and excellent selectivity for Hg²⁺ even in the presence of other analytes. Furthermore, 1 was successfully applied for the ratiometric imaging of intracellular Hg²⁺ and was confirmed to localize specifically within mitochondria. Full article

Solar cell efficiency depends on both photogeneration and charge collection, with the active layer playing a key role in these processes. In organic solar cells (OSCs), where power conversion efficiency (PCE) remains relatively low, understanding the influence of active layer and metal contact thickness on device performance is essential. In this work, we investigate the effect of P3HT:PCBM and Ag thickness on OSC performance by analyzing the evolution of electrical parameters obtained from J-V measurements over five weeks, with particular attention given to resistance-related degradation behavior. The analyzed OSCs had a cell structure composed of Ag/P3HT:PCBM/TiO₂/ITO/glass, and each material was corroborated by XRD and Raman spectroscopy. The thickness of P3HT:PCBM was modulated by varying the number of spin-coated layers from 1 to 3 (ranging from 75 to 160 nm). This variation increases light absorption, as demonstrated by the optical transmittance spectra. However, device degradation became evident after the third week of fabrication, mainly due to an increase in series resistance, which adversely affected the open-circuit voltage (V_OC), fill factor (FF), and overall device efficiency. The best performance was obtained for devices fabricated with two P3HT:PCBM layers and 18 mg of Ag, achieving a maximum PCE of 0.5%. Full article

High-temperature vulcanized (HTV) silicone rubber serves as the core material for composite insulators, and its high-frequency dielectric properties directly dictate its macroscopic insulation performance. However, traditional electrical detection methods encounter a “high-frequency blind zone” above the gigahertz (GHz) range due to limited precision and ambiguous physical mechanisms. In this study, terahertz time-domain spectroscopy (THz-TDS) was employed to characterize the complex permittivity spectra of silicone rubber specimens, incorporated with varying ratios of alumina trihydrate (ATH) and silica (SiO₂) fillers, across the 0.1–3.0 THz frequency range. Experimental results reveal that the terahertz dielectric characteristics of silicone rubber exhibit a pronounced filler dependency: as the ATH content increases from 95 phr to 185 phr, the real part of the permittivity at 1 THz increases by 32%. Notably, all specimens manifest a sharp dielectric transition near 1.2 THz, characterized by distinct dual absorption peaks in the imaginary permittivity spectra. To characterize this non-linear transition, a hybrid Debye–Lorentz model is innovatively introduced. This approach overcomes the inherent limitations of traditional double Debye models, which are restricted to relaxation processes and fail to account for high-frequency resonance. Fitting results and physical analysis demonstrate that the response at 1.2 THz is primarily attributed to the bending vibrations of Si-O-Si bonds in the polymer backbone, alongside the collective vibration modes of Al-O bonds and the hydrogen-bonded network within the fillers. The hybrid model successfully decouples three distinct polarization mechanisms: conduction loss (<0.5 THz), dipole relaxation (0.5–1.0 THz), and lattice resonance (>1.0 THz). This work provides a robust characterization framework for the quantitative evaluation of the high-frequency dielectric response and microstructural integrity of composite insulators. Full article

This study comprehensively investigates the degradation performance of a Mn-doped Zn₂SnO₄ photocatalyst based on time-dependent UV-Vis absorption spectra. Before machine learning modelling, the effects of experimental parameters such as UV–Vis measurement wavelength, reaction time, and Mn doping ratio were statistically validated using One-Way Analysis of Variance (ANOVA) and Multiple Linear Regression (MLR) methods. To overcome the limitations of linear models in representing complex physical systems, an optimized Multi-Layer Perceptron (MLP) architecture was developed to capture the system’s nonlinear dynamics with high accuracy. To validate the model’s out-of-sample prediction capability and prevent data leakage potentially arising from spectral data correlation, the “Leave-One-Doping-Level-Out” (LODLO) cross-validation strategy was applied, during which performance metrics of R²$=0.8889$ and $MSE=0.00238$ were recorded. To make the neural network’s decision-making mechanism transparent, a dual-validation explainability framework comprising Shapley Additive Explanations (SHAP) and Permutation Feature Importance analyses was employed. By quantifying the relative contributions of the experimental parameters to the model predictions, this approach revealed that the UV–Vis measurement wavelength was the dominant predictive variable, followed by the Mn doping ratio and reaction time. This study presents a transparent methodology that offers both strong predictive capability and physically grounded data to shed light on the complex interactions in doped semiconductor photocatalysts. Full article

Conventional oxidative hair dyes rely on aromatic amines, raising concerns about human health and environmental safety. This study reports a natural hair-coloring system using size-controlled ink particles (SIPs, ~170 nm in diameter) from cuttlefish ink and chitosan. Because both SIPs and hair surfaces carry negative charges near neutral pH, original SIPs exhibited poor deposition onto hair. Polyelectrolyte complexation with chitosan reversed the SIP surface charge under acidic conditions (maximum ζ ≈ +41 mV at pH 2.4), enabling electrostatic deposition onto hair fibers. Dynamic light scattering (DLS) revealed pH-responsive aggregation at pH 1.6–1.8 and redispersion at pH 2.8–4.3, while ultraviolet–visible (UV–Vis) spectra confirmed that the broadband absorption of melanin was preserved, consistent with predominantly noncovalent interactions. Scanning electron microscopy (SEM) showed a particle-based composite coating on hair fibers. An optimal SIP:chitosan weight ratio of 10:1 at pH ~4.7 yielded the darkest and most uniform coloration (L* = 32.89, ΔE*_ab = 55.89) without metallic mordants, achieving darker coloration than representative plant-based natural colorants reported in the literature. These results demonstrate a marine-biomass-derived approach to natural black hair coloration with strong darkening performance. Full article

The color origin of precious coral, a highly valued biogenic polycrystalline gemstone, has long remained elusive. In this study, an integrated approach employing spectrophotometry, Raman, FTIR, and UV-Vis spectroscopy, coupled with Spearman correlation analysis, was utilized to investigate a color-graded series of precious coral samples ranging from white to red. The results demonstrate that the calcareous composition of the samples tested in our study consists exclusively of calcite. The actual chromophores are identified as a blend of multiple distinct polyene species, characterized by Raman shifts at 1126 and 1515 cm⁻¹, with density functional theory (DFT) calculations determining the number of conjugated (C=C) bonds in the polyene chain to be 10–11. Inherently exhibiting a red-orange hue, the progressive accumulation of these polyenes drives a systematic color transition from orange to red. Both absorption bands at 314 nm and 532 nm in the UV-Vis spectra are attributed to the polyene pigment molecules. Specifically, the broad 532 nm band is dominated by π-π* electronic transitions, while the 314 nm band likely arises from terminal benzene rings and their derivatives. As the pigment concentration increases, this band exhibits pronounced broadening and an increase in absorbance, accompanied by a redshift in the maximum absorption peak. This spectral evolution leads to an intensified absorption in the yellow-orange region, elucidating the intrinsic mechanism underlying the color transition of precious coral from orange to red with increasing pigment content. This work lays a solid foundation for the non-destructive identification of precious corals and future research on their color genesis. Full article

This work reports the synthesis, characterization, and photocatalytic performance of multifunctional spheres based on AgNP-doped TiO₂-Fe₃O₄ embedded in an alginate–chitosan biopolymeric matrix for the removal of organic contaminants from water. The composite powders exhibited a nanocrystalline structure composed of anatase TiO₂ (~20 nm) and magnetite (~25 nm), with homogeneously dispersed Ag nanoparticles, as observed by SEM. The spheres presented a mainly submicrometric particle size distribution (0.55–0.92 µm), favoring high surface area and colloidal stability. Under simulated solar irradiation, the material achieved efficient photocatalytic degradation of methylene blue, with a pseudo-first-order rate constant of 0.112 h⁻¹ and ~46% decolorization after 5 h. UV-Vis spectra showed progressive attenuation of the dye absorption band without accumulation of intermediates. Magnetic recovery tests confirmed rapid separation and reuse without performance loss. The enhanced activity is attributed to the synergistic interaction among plasmonic Ag, photocatalytic TiO₂, redox-active Fe₃O₄, and the adsorptive carbon–biopolymer matrix. The material exhibited strong antibacterial activity, achieving over 90% removal of fecal coliforms after 5 h of irradiation. Therefore, the developed AgNP-doped TiO₂-Fe₃O₄ spheres represent a sustainable, reusable, and efficient material for solar-assisted water sanitation. Full article

We report the synthesis and characterization of the photophysical characterization of a series of rhodamine (Rho)–perylenebisimide (PBI) electron donor–acceptor dyad/triads containing flexible alkyl spacers (ethylene or hexylene chains). Steady-state absorption and emission, femtosecond and nanosecond transient absorption (fs-TA and ns-TA), cyclic voltammetry, triplet–triplet energy transfer (TTET) experiments and DFT/TD-DFT calculations were combined to elucidate the excited-state dynamics. fs-TA spectral study indicates fast decay of the S₁ state and formation of the ³PBI state (0.32–663 ps), which is supported by the ns-TA spectra. The localized PBI triplet (³PBI*) exhibits unusually long lifetimes (up to 272 μs) as determined by the TTET experiment. No long-lived charge-separated (CS) state was observed. While a Förster resonance energy transfer (FRET) probably occurs between PBI and the open-ring rhodamine, a photo-induced electron transfer is proposed to be responsible for the quenching of the fluorescence of the PBI moiety. Full article

The determination of the linear optical constants of solids is an important part of solid state optical characterization. Reflection spectroscopy and ellipsometry of surfaces or thin solid films represent established techniques to access those optical constants; however, they may suffer from ambiguity in the obtained optical constants. We discuss methods for identifying the physically meaningful solution from the solution multiplicity, making use of a proper combination of independent measurements. Elaborating contours of constant reflectance (iso-reflectance curves) facilitates the reliable identification of correct optical constants. A numerical criterion is further provided to select suitable combinations of measurements. The procedure is demonstrated through its application to simulated spectra of a Nb₂O₅ film in the spectral region where the onset of the fundamental absorption edge is observed. Full article

This study investigates agar–starch composite bioplastic films formulated with five agar-to-starch ratios (1:1, 2:1, 3:1, 4:1, and 5:1) to evaluate how composition influences material performance. Films were produced by solution casting with glycerol as a plasticizer and characterized through tensile testing (ASTM D882-18), DSC, TGA, FTIR, water absorption measurements, physical property assessment, and biodegradability tests including water, UV, and soil degradation. Mechanical results showed that the 3:1 formulation (A3S1) exhibited the highest tensile strength (2.78 MPa) with moderate elongation (57.25%), while the 1:1 formulation (A1S1) showed the greatest flexibility (76.38% elongation) but lower strength (2.07 MPa). Thermal analysis indicated improved thermal stability with increasing agar content, with onset degradation temperatures ranging from 42.89 °C to 51.84 °C and melting points from 99 °C to 108 °C. FTIR spectra showed no new major absorption bands, with only minor shifts in selected bands, indicating component interactions without evidence of new chemical bond formation. Films with higher starch content displayed increased thickness, weight per area, and water absorption. Overall, adjusting agar–starch ratios produced distinct combinations of mechanical, thermal, and physical properties, with the 3:1 ratio offering the best balance of strength and water resistance. All formulations showed measurable biodegradation under water, UV, and soil conditions, indicating environmental degradability. Full article

Surface stain contamination poses a critical barrier to the automated, high-precision fiber identification required for industrial-scale waste textile recycling. In this study, a dataset comprising 120 physical specimens (yielding 1200 regions of interest, ROIs) across 12 contamination categories was constructed by contaminating cotton, polyester, and poly-cotton blend textiles with carbon black, protein, and oil stains. The spectral interference effects of stains—including baseline drift and spectral overlapping induced by physical shielding and chemical absorption—were systematically analyzed. To identify the optimal classification pipeline, three mathematical preprocessing methods (First Derivative, FD; Standard Normal Variate, SNV; and Multiplicative Scatter Correction, MSC) were evaluated alongside Support Vector Machine (SVM) and One-Dimensional Convolutional Neural Network (1D-CNN) models. Results show that among the SVM-based pipelines, the FD-SVM model effectively resolves overlapping absorption peaks, achieved an average accuracy of 98.17% ± 1.33%, but remains highly dependent on mathematical preprocessing. In contrast, the 1D-CNN model employing a progressive stacking architecture of multi-scale convolutional kernels attains a highly robust mean accuracy of 99.58% ± 0.56% under a strict specimen-level 10-fold cross-validation. It achieves this by directly utilizing radiometrically calibrated raw spectra, thereby effectively bypassing manual spectral feature engineering. These findings demonstrate that Hyperspectral Imaging coupled with end-to-end deep learning provides a feasible and industrially deployable solution for simultaneous stain detection and fiber identification in waste textile sorting. Full article