Search Results (748)

Coloured and variegated leaves are common in shade-tolerant ornamentals. However, it remains unclear whether their photosynthetic performance is determined mainly by pigment abundance or by the organisation of chloroplasts and thylakoids. We tested this in three Epipremnum aureum phenotypes (‘Neon’, ‘Golden’ and ‘Jade’) that share a genetic background but contrast in leaf colour, chloroplast density and thylakoid membrane abundance. Plants were grown in a greenhouse and assessed by hyperspectral and thermal imaging, infrared gas exchange analysis, chlorophyll a fluorescence measurements, and structural, ultrastructural and biochemical analyses. Traits were integrated by principal component analysis, with the quantum yield of CO₂ assimilation per absorbed photon (αCO_2,abs) as the response variable. ‘Neon’ leaves had high specific leaf area and approximately 55% lower maximum Rubisco carboxylation (Vc_MAX) and electron transport capacity (J_MAX) than ‘Jade’, as well as reduced chloroplast and thylakoid abundance and warmer canopies, despite carotenoid enrichment. JIP-test parameters and fluorescence light–response curves showed high absorption and dissipation per PSII reaction centre, elevated excitation pressure, modest non-photochemical quenching (NPQ), low αCO_2,abs, small carbohydrate pools and low intrinsic water-use efficiency. ‘Jade’ leaves developed thick mesophyll with dense chloroplast populations, extensive thylakoid networks, highest NPQ, cool canopies and large carbohydrate reserves, whereas ‘Golden’ leaves combined thin laminae and intermediate chloroplast–thylakoid organisation with early light saturation of CO₂ assimilation and the highest intrinsic water-use efficiency. Principal component analysis revealed a structural axis of chloroplast and thylakoid organisation that better predicted αCO_2,abs, net carbon gain and canopy temperature than pigment abundance. In variegated E. aureum, ‘photon economy’ is therefore governed primarily by chloroplast and thylakoid membrane organisation and abundance rather than by carotenoid accumulation. Full article

MXene-based microwave absorbers have received extensive attention owing to their high electrical conductivity, abundant interfacial polarization sites, and tunable surface terminations. However, the structure–property relationship of MXene composites remains highly nonlinear, and the design of high-efficiency absorbers still relies heavily on trial-and-error experiments. Herein, multidimensional magnetic components, including zero-dimensional (0D) Fe₃O₄ nanoparticles, one-dimensional (1D) Fe₃O₄/Co₃O₄ nanowires, and two-dimensional (2D) Fe₃O₄-based heterostructures, were rationally integrated with Fe/MXene and Fe/Co/MXene nanosheets to engineer synergistic dielectric and magnetic losses. Comprehensive electromagnetic characterization and loss mechanism analysis reveal that the structural dimensionality strongly impacts impedance matching and attenuation capability. To further enable predictive and data-driven optimization, a machine learning framework was established to correlate the microstructure, component ratio, thickness, and electromagnetic parameters with the microwave absorption performance (e.g., minimum reflection loss (RL_min), effective absorption bandwidth (EAB)). The optimized multidimensional composite achieves an RL_min of −56.4 dB at 10.2 GHz with an EAB of 8.4 GHz (9.6–18.0 GHz) at a thin matching thickness of 1.8 mm. The machine learning model demonstrates excellent accuracy (R² = 0.947) and enables the inverse design of absorber geometries to target specific operational frequencies. This work provides a generalizable paradigm for the intelligent design of MXene-based microwave absorbers and opens up broader opportunities for the AI-accelerated discovery of advanced electromagnetic functional materials. Full article

Plastic pollution represents a significant challenge for the building industry, where synthetic foils are extensively used as acoustic absorbers or vapour barriers but persist in the environment for decades, causing risks to ecosystems and human health. In addition, conventional construction materials such as concrete and glass often provide poor acoustic performance, leading to a growing reliance on synthetic acoustic absorbers. In this study, we propose alginate—a biopolymer derived from brown seaweed—as an alternative sustainable material for indoor acoustic conditioning. Thin, bendable, and transparent alginate foils were fabricated and characterized in the impedance tube to assess their sound absorption properties. Results reveal that alginate foils achieve acoustic absorption coefficients comparable to conventional synthetic-based absorbers, while offering biodegradability and a renewable origin. Their physical properties further support potential integration into indoor architectural design, where flexible and transparent properties are desirable. Overall, the findings highlight alginate’s potential as an environmentally friendly replacement for synthetic acoustic foils, supporting the goals of acoustic sustainability and the associated long-term impacts of plastic pollution in the built environment. Full article

Background/Objective: Photocatalytic oxidation is often interpreted as evidence of microplastic degradation, yet whether surface chemical modification under dry conditions corresponds to meaningful bulk polymer breakdown remains unclear. To help fill that gap, this study investigates the concentration-dependent photocatalytic aging of polystyrene (PS) microplastics incorporated into Titanium dioxide-coated hollow glass microsphere (TiO₂–HGM) composites under solid-state UV irradiation, with emphasis on distinguishing surface oxidation from bulk degradation. Methods: Thin-film composites containing 1 wt%, 5 wt%, and 10 wt% TiO₂–HGMs were exposed to UV-A irradiation (365 nm) for 183.5 h under dry conditions. Chemical and structural changes were evaluated using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and UV–visible spectroscopy. The carbonyl index (CI) was calculated from baseline-corrected integrated absorbance areas relative to an invariant aromatic reference band. Results: CI values increased from 0.483 (1 wt%) to 0.702 (5 wt%) and slightly decreased to 0.645 (10 wt%), indicating non-linear oxidation behavior and partial saturation. XPS showed a corresponding rise in the O/C ratio from 0.42 to 0.51. In contrast, UV–visible spectra exhibited minimal changes in aromatic absorption. Conclusions: Increasing photocatalyst concentration enhances surface oxidation but does not induce proportional bulk polymer degradation under solid-state conditions. Full article

High-resolution short-wave infrared (SWIR) imaging requires photodetectors (PDs) with simultaneously low dark current and high responsivity. To achieve this goal, we demonstrate low-defect bulk germanium-on-insulator (bulk-GeOI) PDs designed for enhanced 1550 nm absorption and suppressed dark current via a resonant cavity and low-defect material platform. Devices were fabricated by direct bonding low-defect bulk Ge and thinning it to ~1300 nm, with an intrinsic layer thickness of only 800 nm. This design avoids epitaxial defects to lower intrinsic dark current while forming a resonant cavity for enhanced responsivity at 1550 nm. Precise doping and Al₂O₃/Si₃N₄ bilayer sidewall passivation were employed. From a design perspective, using low-defect bulk Ge minimizes the defects from epitaxial growth and reduces intrinsic dark current, while thinning the Ge layer enhances the resonant cavity effect to improve 1550 nm responsivity. Experimentally, despite the thin absorbing layer, our devices achieved nA-level dark currents (e.g., 18 nA at −1 V for 10 μm devices) alongside high responsivities. Detailed analysis indicates that this dark current is predominantly attributed to surface and sidewall defects from mesa etching, with minimal contribution from low-defect bulk material defects, validating the effectiveness of the bulk-Ge approach in suppressing intrinsic bulk leakage. Optically, the devices achieved high responsivities of 0.85 A/W (1310 nm) and 0.72 A/W (1550 nm), corresponding to external quantum efficiencies of 80.6% and 57.7%, respectively. This work establishes the bulk-GeOI platform as a promising path toward high-performance SWIR PDs, successfully decoupling high responsivity from bulk leakage and paving the way for future gains through refined surface and interface engineering. Full article

Magnetic metals are of considerable importance for stealth technology and electromagnetic pollution control. However, they suffer from inherent limitations, such as the Snoek limit and narrow absorption bandwidth, which restrict their applications in complex scenarios. To address these challenges, this review systematically summarizes the recent advances of magnetic metal-based microwave-absorbing materials (MAMs), focusing on four core directions: alloy design, composite engineering, structural regulation, and preparation technology. The intensity and frequency bands of absorption in alloys are dictated by the material’s composition as well as its structural attributes. Moreover, composite systems incorporating carbon materials, MXenes, oxides, ceramics, and conductive polymers are discussed, where the synergistic design of components optimizes impedance matching and loss mechanisms. Key structural design strategies include core-shell structures, interface engineering, self-assembled hierarchical structures, and macroscopic structural design. These structures achieve the synergistic improvement of thin, lightweight, broadband, and strong absorption performance by enhancing interface polarization, multiple scattering, and resonance effects, while endowing materials with excellent environmental stability. Notably, metamaterial-based designs can further achieve an ultrawide bandwidth spanning 0.3–18 GHz. Additionally, preparation processes are crucial for regulating the microstructure and activating loss mechanisms. This review aims to offer theoretical and practical insights for developing high-performance, multifunctional magnetic MAMs. Full article

Addressing the technical bottlenecks of excessive surface density in traditional magnetic metal powder absorbers and excessive thickness in conventional foam-based absorbers, this study proposes a novel lightweight, ultra-wideband microwave-absorbing metamaterial. This metamaterial, through multi-layer and multi-dimensional structural design, has constructed a composite structure composed of a resistive film frequency-selective surface, a foam wave-absorbing medium layer and a reflective layer, achieving the controllable regulation of microwave absorption performance and the integration of structure and function. The research results show that the fabricated absorbing metamaterial achieves efficient electromagnetic wave absorption over a wide frequency band of 94 GHz under the ultra-light and ultra-thin conditions with a density as low as 0.078 g/cm³ and a thickness of only 4.9 mm. This study provides an effective design concept and solution for developing new lightweight, thin-layer, wide-band, and highly microwave-absorbing materials. Full article

Superconducting transition-edge sensors (TESs) exhibit excellent single-photon detection performance. The quantum efficiency (QE), which quantifies the probability that an incident photon is absorbed and converted into a measurable signal, is strongly governed by the optical properties of the constituent thin films. Specifically, for typical TES device architectures where optical transmission is negligible, maximizing the QE requires the minimization of surface reflectance to ensure high photon absorptance. In this work, we systematically study how anodic oxidation modifies the optical response of superconducting titanium (Ti) thin films that are relevant for TES devices. Anodization is carried out under well-controlled constant-current conditions in an aqueous electrolyte containing ammonium pentaborate and ethylene glycol. Experimentally, we show that anodic oxidation substantially reduces the ultraviolet (UV) reflectance and induces a monotonic redshift of the reflectance minimum as the anodic oxidation cutoff voltage (V_ocv) increases. Finite-difference time-domain (FDTD) simulations based on spectroscopic ellipsometry data reproduce the measured spectra with good fidelity for most samples, validating the extracted optical constants. By comparing samples prepared at different current densities and oxidation times, we identified V_ocv as the primary parameter controlling the reflectance response, because it determines the thickness and effective optical properties of the anodic TiO_x layer. Under optimized conditions, reflectance values below 1% in the 320.9–340.2 nm wavelength range and below 2% in the 316.3–346.3 nm range are achieved, indicating a significant enhancement in potential absorptance. These results demonstrate that anodic oxidation provides a simple, post-fabrication, and voltage-tunable route for engineering the UV optical response of Ti-based TES structures and for enhancing their potential QE by suppressing reflection losses. Full article

Sandwich panels with trapezoidal (corrugated) cores combine low weight, high specific stiffness, and energy absorption capability. This study analyzes four configurations with different core heights by means of microstructural analyses (optical microscopy, SEM/EDS, XRD) and quasi-static compression tests. The tests yield stress–strain curves with an initial linear stage, a peak, a plateau, and a densification stage. Peak stresses range from 0.5 MPa for the thickest core (P1) to 6.2 MPa for the thinnest core (P4), while the energy absorbed density (EAD) increases with strain: at ε = 30% it varies from 0.031 to 0.670 J/cm³, and at ε = 50% the thin-core configuration reaches ≈1.113 J/cm³. The face sheets and the core are both manufactured from AA 3000 series (Al–Mn) aluminum alloy; widespread micro-porosity and Fe/Mn-rich phases are observed by SEM/EDS. XRD confirms aluminum with different peak intensities ascribable to the manufacturing texture. Increasing the core height promotes earlier local/global instabilities and reduces the peak stress; the thinnest core displays higher stiffness and peak loads. These findings support the use of trapezoidal corrugation where low weight and progressive strain are required. Full article

Piezochromic nanomaterials, whose optical responses can be reversibly tuned by mechanical stimuli, have recently gained prominence as versatile platforms for strain-programmable light–matter interactions. Their mechanically responsive band structures, excitonic states, and defect energetics have enabled a wide range of optoelectronic demonstrations—including pressure-tunable emitters, reconfigurable photonic structures, and adaptive modulators—which collectively highlight the unique advantages of mechanical degrees of freedom for controlling optical functionality. These advances naturally suggest new opportunities in photovoltaic technologies, where experimentally validated phase stabilization and defect reorganization under low-strain thin-film conditions could address long-standing limitations in solar absorbers and device stability. Meanwhile, stress-mediated bandgap tuning—largely inferred from high-pressure laboratory studies—presents a conceptual blueprint for future adaptive spectral response and structural self-monitoring. However, the application of these mechanisms faces a major challenge in bridging the magnitude gap between GPa-level high-pressure phenomena and the low-strain regimes of realistic operational environments. Future development requires advances in low-threshold responsive materials, innovative strain-amplifying device architectures, and the pursuit of intelligent, multi-functional system integration. Full article

We propose a 1D photonic crystal with nonlinear graphene–spacer–graphene truncation, which enables a tunable, non-monotonic, and intensity-dependent transmission response. By employing synthetic geometrical space to obtain Fermi arc states, the structure is designed to support a real-space topologically protected Tamm plasmon polariton, revealing an intensity-dependent transmission peak within the THz spectral range. As such, the proposed thin-film structure may serve as a nonlinear DBR element that can be integrated into a laser cavity to provide intensity-selective feedback, thereby facilitating controllable pulse shaping and enabling passive pulse formation mechanisms such as mode-locking or Q-switching. Due to its topological robustness, spectral scalability, and electrical tunability via graphene biasing, the platform provides a new route toward compact, reconfigurable nonlinear reflectors for efficient and controllable laser pulse generation, thereby extending the functionality of conventional saturable absorbers and semiconductor DBRs. Full article

In response to the significant threat posed by low-frequency P-band anti-stealth radar to aircraft stealth capabilities, this paper examines the inverse design of electromagnetic parameters for a single-layer, thin P-band radar absorbing material. An efficient computational model is constructed by integrating impedance boundary conditions with the characteristic basis function method. The NSGA-II genetic algorithm is employed to accomplish multi-objective co-optimization of electromagnetic parameters and material thickness. Results demonstrate that the optimized single-layer RAM, with a relative permittivity of μ_r = 3.3078 + j3.9018 and permeability of ε_r = 2.3522 + j6.9519, exhibits outstanding P-band absorption characteristics within a thickness constraint of only 1 mm. Applying this RAM to aircraft wing components’ leading/trailing edges, intake duct cavities, and lip areas effectively suppresses edge diffraction and cavity scattering. The target achieves a maximum forward average RCS reduction of −13.97 dB and a maximum rearward average RCS reduction of −5.03 dB, maintaining stable performance within a pitch angle range of 0° ± 5°. Full article

Among the most promising alloys for photovoltaic applications is copper–indium–gallium–selenide (CIGS) because of its enhanced optical properties. This study examines the influence of current density and pulse timing on the electrodeposition of Cu(In, Ga)Se₂ (CIGS) thin films from a dilute electrolyte. It assesses how these parameters affect deposition quality, film characteristics, and device performance. CIGS absorber layers were electrodeposited using a pulsed-current method, with systematic variations in current density and pulse on/off durations in a low-concentration solution. The deposited precursors were subsequently selenized and incorporated into fully assembled CIGS solar cell architectures. Structural characteristics were analyzed by X-ray diffraction (XRD), whereas composition and elemental distribution were assessed by energy-dispersive X-ray spectroscopy (EDS). Optical properties pertinent to photovoltaic performance were evaluated through transmittance and reflectance measurements. The results indicate that moderate current densities, when combined with brief off-times, produce dense, microcrack-free films exhibiting enhanced crystallinity and near-stoichiometric Cu/(In + Ga) and Ga/(In + Ga) ratios, in contrast to films deposited at higher current densities and extended off-times. These optimized pulse parameters also produce absorber layers with advantageous optical band gaps and improved device performance. Overall, the study demonstrates that regulating pulse parameters in attenuated electrolytes is an effective strategy to optimize CIGS film quality and to facilitate the advancement of economical, solution-based fabrication methods for high-performance CIGS solar cells. Full article

The fabrication of undoped and aluminium-doped zinc oxide thin films on quartz glass substrates through the aqueous spray method is reported. The prepared aqueous precursor solutions containing Zn²⁺ and varying mole percentages (0, 2, 4, and 8%) of Al³⁺ complexes were spray-coated onto quartz glass substrates preheated at 180 °C. The as-sprayed films obtained were then heat-treated at 450 °C for 30 min in a furnace to produce the various thin films. The structural and optical properties of the resultant thin films were analysed using the X-ray diffractometer (XRD) and ultraviolet–visible (UV-Vis) spectrophotometer. The XRD results revealed that the fabricated thin films have a prominent peak correlating to the (002) Miller index, which is the preferred orientation of the zinc oxide hexagonal wurtzite phase. The fabricated thin films with a film thickness of approximately 189 nm absorb light in the visible region and have a transmittance of over 80% even after being doped with aluminium. The photocatalytic activities of the thin films were evaluated via visible light irradiation of an aqueous methyl orange solution, and the Al-doped ZnO thin films exhibited good photocatalytic activities, which resulted in an increase in the doping mole percentages of aluminium. Full article

Cadmium-free buffer layers are pivotal for the sustainable development of thin-film photovoltaics. This work numerically investigates SnS₂ as a high-performance, environmentally benign alternative to CdS for antimony selenosulfide (Sb₂(S,Se)₃) solar cells using AFORS-HET software. The SnS₂/Sb₂(S,Se)₃ heterojunction exhibits a significantly lower conduction band offset (CBO ≈ 0.23 eV) than its CdS counterpart (CBO ≈ 0.49 eV), which is identified as the primary factor for suppressed interface recombination and enhanced electron injection efficiency. A comprehensive optimization strategy is presented: tuning the S content in Sb₂(S,Se)₃ to 40% optimizes the trade-off between band gap widening and hole transport barrier at the ETL/absorber interface; adjusting the absorber thickness to 340 nm balances light absorption and carrier collection efficiency; and elevating the SnS₂ carrier concentration to 10²¹ cm⁻³ strengthens the built-in potential and induces a beneficial hole-blocking “spike” at the front contact. The synergistically optimized device achieves a power conversion efficiency (PCE) of 10.39%, a substantial improvement over the 7.56% efficiency of the CdS-based reference cell in our simulation framework. Full article