Search Results (197)

This work aimed to advance the knowledge in the field of eco-friendly dielectrics with applicative relevance for future energy-related technologies. New multicomponent composites were prepared by using a cellulose ether/citric acid mixture as the matrix, which was gradually filled with strontium titanate nanoparticles (5–20 wt%). In this case, citric acid can act as a crosslinking agent for the polymer but also can react differently with the other counterparts from the composite as a function of the solvent used (H₂O and H₂O₂). This led to considerable differences in the morphological, thermal, optical, and electrical characteristics due to distinct solvent-driven interactions, as revealed by the infrared spectroscopy investigation. Hence, in contrast to H₂O, the oxidizing activity of H₂O₂ led to changes in the surface morphology, a greater transparency, a greater yellowness, an enhanced refractive index, and higher permittivity. These data provide new pathways to advance the optical and dielectric behavior of eco-compatible materials for energy devices by the careful selection of the composite’s components and the modulation of the molecular interactions via solvent features. Full article

Electrochromic devices (ECDs) capable of modulating both visible color and infrared (IR) emissivity are promising for applications in smart thermal camouflage and multifunctional displays. However, conventional transmissive ECDs suffer from limited IR modulation due to the low IR transmittance of transparent electrodes. Here, we report a reflection-type electrochromic zinc-ion battery (HWEC-ZIB) using a self-doped polyaniline nanorod film (SP(ANI-MA)) as the active layer. By positioning the active material at the device surface, this structure avoids interference from transparent electrodes and enables broadband and efficient IR emissivity tuning. To prevent electrolyte-induced IR absorption, a thermal lamination encapsulation method is employed. The optimized device achieves emissivity modulation ranges of 0.28 (3–5 μm) and 0.19 (8–14 μm), delivering excellent thermal camouflage performance. It also exhibits a visible color change from earthy yellow to deep green, suitable for various natural environments. In addition, the HWEC-ZIB shows a high areal capacity of 72.15 mAh cm⁻² at 0.1 mA cm⁻² and maintains 80% capacity after 5000 cycles, demonstrating outstanding electrochemical stability. This work offers a versatile device platform integrating IR stealth, visual camouflage, and energy storage, providing a promising solution for next-generation adaptive camouflage and defense-oriented electronics. Full article

Leaves react with rail steel and form a tribofilm, causing very low friction in the wheel/rail interface. This work uses twin-disc tribological testing with the addition of leaf particulates to simulate the reaction and resulting reduction in the friction coefficient in a laboratory setting. Diffuse Reflectance Fourier-Transform Infrared Spectroscopy was carried out on the organic material and the layers that formed on the twin-disc surface. Dark material, visibly similar to leaf layers formed on tracks during autumn, was used along with a transparent thin film. This “non-visible contamination” has been reported to cause low-adhesion problems on railways, but has not previously been characterised. This article discusses the nature of these layers and builds upon earlier studies to propose a degradation and bonding mechanism for the leaf material. This understanding could be used to improve friction management methods employed to deal with low adhesion due to leaves. Full article

A scalable synthesis of two-dimensional titanium nitride chloride (TiNCl) via flash Joule heating (FJH) using titanium tetrachloride (TiCl₄) precursor has been developed. This single-step method overcomes traditional synthesis challenges, including high energy consumption, multi-step procedures, and hazardous reagent requirements. The structural and chemical properties of the synthesized TiNCl were characterized through multiple analytical techniques. X-ray diffraction (XRD) patterns confirmed the presence of TiNCl phase, while Raman spectroscopy data showed no detectable oxide impurities. Fourier transform infrared spectroscopy (FTIR) analysis revealed characteristic Ti–N stretching vibrations, further confirming successful titanium nitride synthesis. Transmission electron microscopy (TEM) imaging revealed thin, plate-like nanostructures with high electron transparency. These analyses confirmed the formation of highly crystalline TiNCl flakes with nanoscale dimensions and minimal structural defects. The material exhibits excellent structural integrity and phase purity, demonstrating potential for applications in photocatalysis, electronics, and energy storage. This work establishes FJH as a sustainable and scalable approach for producing MXenes with controlled properties, facilitating their integration into emerging technologies. Unlike conventional methods, FJH enables rapid, energy-efficient synthesis while maintaining material quality, providing a viable route for industrial-scale production of two-dimensional materials. Full article

The inspection of encapsulated MEMS devices typically relies on destructive methods which compromise the structural integrity of samples. In this work, we present the concept and preliminary experimental validation of a laser scanning setup to non-destructively inspect silicon-encapsulated microstructures by measuring small variations of transmitted light intensity in the near-infrared spectrum. This method does not require any particular sample preparation or damage, and it is based on the higher degree of transparency of silicon in the near-infrared and the transmission contrast resulting from the Fresnel reflections observed at the interfaces between the different materials of the MEMS device layers. We characterise the small feature resolving performance of the laser scanning setup using standard targets, and experimentally demonstrate the inspection of a MEMS latching device enclosed within silicon covers, comparing the contrast measurements with theoretical predictions. Full article

Aluminum nitride (AlN) thin films were deposited on SiO₂ substrates by RF-magnetron sputtering at varying powers (110–140 W) and subsequently subjected to thermal annealing at 450 °C under nitrogen atmosphere. A comprehensive multi-technique investigation—including X-ray reflectometry (XRR), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), optical profilometry, spectroscopic ellipsometry (SE), and electrical measurements—was performed to explore the physical structure, morphology, and optical and electrical properties of the films. The analysis of the film structure by XRR revealed that increasing sputtering power resulted in thicker, denser AlN layers, while thermal treatment promoted densification by reducing density gradients but also induced surface roughening and the formation of island-like morphologies. Optical studies confirmed excellent transparency (>80% transmittance in the near-infrared region) and demonstrated the tunability of the refractive index with sputtering power, critical for optoelectronic applications. The electrical characterization of Au/AlN/Al sandwich structures revealed a transition from Ohmic to trap-controlled space charge limited current (SCLC) behavior under forward bias—a transport mechanism frequently present in a material with very low mobility, such as AlN—while Schottky conduction dominated under reverse bias. The systematic correlation between deposition parameters, thermal treatment, and the resulting physical properties offers valuable pathways to engineer AlN thin films for next-generation optoelectronic and high-frequency device applications. Full article

Fiber–aerogel composites have gained significant attention as high-performance thermal insulation materials due to their unique microstructure, which suppresses conductive, convective, and radiative heat transfer. At room temperature, silica aerogels in particular exhibit ultralow thermal conductivity (<0.02 W/m·K), which is two to three times lower than that of still air (0.026 W/m·K). Their brittle skeleton and high infrared transparency, however, restrict how well they insulate, particularly at high temperatures (>300 °C). Incorporating microscale fibers into the aerogel matrix enhances mechanical strength and reduces radiative heat transfer by increasing scattering and absorption. For instance, it has been demonstrated that adding glass fibers reduces radiative heat transmission by around 40% because of increased infrared scattering. This review explores the fundamental mechanisms governing radiative heat transfer in fiber–aerogel composites, emphasizing absorption, scattering, and extinction coefficients. We discuss recent advancements in fiber-reinforced aerogels, focusing on material selection, structural modifications, and predictive heat transfer models. Recent studies indicate that incorporating fiber volume fractions as low as 10% can reduce the thermal conductivity of composites by up to 30%, without compromising their mechanical integrity. Key analytical and experimental methods for determining radiative properties, including Fourier transform infrared (FTIR) spectroscopy and numerical modeling approaches, are examined. The emissivity and transmittance of fiber–aerogel composites have been successfully measured using FTIR spectroscopy; tests show that fiber reinforcement at high temperatures reduces emissivity by about 15%. We conclude by outlining the present issues and potential avenues for future research to optimize fiber–aerogel composites for high-temperature applications, including energy-efficient buildings (where long-term thermal stability is necessary), electronics thermal management systems, and aerospace (where temperatures may surpass 1000 °C), with a focus on improving the materials’ affordability and scalability for industrial applications. Full article

With the increasing energy consumption of buildings, transparent heat mirror films have been widely used in building windows to enhance energy efficiency owing to their excellent spectrally selective properties. Previous studies have typically focused on spectral selectivity in the visible and near-infrared bands, as well as single-parameter optimization of film materials or thickness, without fully exploring the performance potential of the films. To address the limitations of traditional design methods, this paper proposes a deep reinforcement learning-based approach that employs an adaptive strategy network to optimize the thin-film material system and layer thickness parameters simultaneously. Through inverse design, a Ta₂O₅/Ag/Ta₂O₅/Ag/Ta₂O₅ (42 nm/22 nm/79 nm/22 nm/40 nm) thin-film structure with broadband spectral selectivity was obtained. The film exhibited an average reflectance of 75.5% in the ultraviolet band and 93.2% in the near-infrared band while maintaining an average visible transmittance of 87.0% and a mid- to far-infrared emissivity as low as 1.7%. Additionally, the film maintained excellent optical performance over a wide range of incident angles, making it suitable for use in complex lighting environments. Building energy simulations indicate that the film achieves a maximum energy-saving rate of 17.93% under the hot climatic conditions of Changsha and 16.81% in Guangzhou, demonstrating that the designed transparent heat mirror film provides a viable approach to reducing building energy consumption and holds significant potential for practical applications. Full article

We present a thoughtfully curated collection of laboratory demonstrations, simulations, and straightforward experiments that explore the fundamental processes underlying greenhouse effect (GHE), climate, atmospheric physics, and Earth’s energy balance. The objective is to connect theory and practice in climate science education and address common student misconceptions. The activities are structured to guide students in constructing simple models of Earth’s radiative equilibrium. Experimental activities cover essential concepts such as the electromagnetic spectrum, radiation–matter interaction, thermal radiation, and energy balance. Physical experiments include visualizing the spectrum with a homemade spectroscope and an infrared (IR) thermal camera, studying absorption and selective transparency when light interacts with different materials, measuring the power emitted by a heated filament, and using simple models, such as black and white discs or a leaking bucket, to understand radiative equilibrium and steady states. This sequence was piloted in a physics education laboratory class with 85 university students enrolled in mathematics and physics courses for future teachers. To assess comprehension improvement, pre- and post-tests involving the production of drawings and explanations related to the GHE were administered to all students. These activities also aim to promote critical thinking and counter climate misinformation and denial. The results showed a significant improvement in understanding fundamental GHE concepts. Additionally, a small subset of students was interviewed to explore the psychological and social dimensions related to the climate crisis. Full article

Background: This study aimed to analyze and compare the translucency and marginal adaptation of five resin-based materials used as occlusal sealants, both before and after simultaneous fatigue and thermocycling. Two null hypotheses were tested: (1) All tested materials allow the transillumination of sealed occlusal carious lesions. (2) There are no differences in marginal adaptation before and after simultaneous fatigue and thermocycling. Methods: Forty extracted human molars with early occlusal caries lesions were randomly divided into five equal groups. Near-infrared transillumination images of cleaned occlusal surfaces were captured before and after applying the following sealants: (I) OptiBond FL (adhesive alone), (II) OptiBond FL (primer and adhesive) (Kerr Corp., Brea, CA, USA), (III) Scotchbond Universal (3M, St. Paul, MN, USA) combined with OptiBond FL adhesive, (IV) Fissurit (VOCO GmbH, Cuxhaven, Germany), (V) Helioseal Clear (Ivoclar Vivadent AG, Schaan, Liechtenstein). A scanning electron microscope was used to assess marginal adaptation before and after simultaneous fatigue and thermocycling. The percentages of continuous margins (CMs) were quantified before and after the fatigue test and statistically compared (Shapiro–Wilk Normality test, two-way ANOVA with Fisher’s post hoc test). Results: Helioseal Clear and Fissurit were fully transparent under near-infrared transillumination. The percentage of closed margins significantly decreased after loading in one group: OptiBond FL primer application before adhesive application significantly reduced marginal adaptation. Conclusion: OptiBond FL (adhesive), Scotchbond Universal with OptiBond FL (adhesive), Fissurit, and Helioseal Clear provided excellent marginal adaptation. However, using OptiBond FL primer on enamel negatively impacted adaptation. Helioseal Clear and Fissurit, as transparent sealants, may allow lesion monitoring using an 850 nm transillumination camera. Full article

The aim of this study was to quantitatively evaluate the swelling and transparency behaviour of Contaflex soft contact lens materials with varying water-content (38–77%) using high-resolution digital imaging and infrared LiDAR. Contaflex materials with 38%, 55%, 58%, 67% and 77% nominal water-contents, denoted as C38, C55, C58, C67, and C77, were tested. Hydrogel samples (N = 5 per group) were monitored over 24 h in pH 7.1 phosphate-buffered saline. Dimensional changes were assessed via linear and radial expansion factors (LEF and REF), and transparency was tracked during hydration. All groups exhibited rapid initial swelling followed by continued expansion. LEF and REF values increased with water-content; C77 reached LEF and REF values of 1.563 ± 0.093 and 1.536 ± 0.052, while C38 stabilised near 1.201 ± 0.019 and 1.179 ± 0.011, respectively. Refractive index decreased with hydration, from 1.552 in C38 to 1.372 in C77. Power simulations revealed deviations beyond ISO tolerance limits in most materials, particularly those with higher water-content. Transparency changes were consistent with swelling dynamics. These findings support the need for material-specific design adjustments to account for hydration-related dimensional and optical changes in soft contact lenses. Full article

Novel wide-bandgap ZnO, BeO, and ZnBeO materials have recently gained considerable interest due to their stellar optoelectronic properties. These semiconductors are being used in developing high-resolution, flexible, transparent nanoelectronics/photonics and achieving high-power radio frequency modules for sensors/biosensors, photodetectors/solar cells, and resistive random-access memory applications. Despite earlier evidence of attaining p-type wz ZnO with N doping, the problem persists in achieving reproducible p-type conductivity. This issue is linked to charging compensation by intrinsic donors and/or background impurities. In ZnO: Al (Li), the vibrational features by infrared and Raman spectroscopy have been ascribed to the presence of isolated ${\mathrm{A}\mathrm{l}}_{\mathrm{Z}\mathrm{n}}{(\mathrm{L}\mathrm{i}}_{\mathrm{Z}\mathrm{n}})$ defects, nearest-neighbor (NN) ${[\mathrm{A}\mathrm{l}}_{\mathrm{Z}\mathrm{n}}{-\mathrm{N}}_{\mathrm{O}}$] pairs, and second NN ${[\mathrm{A}\mathrm{l}}_{\mathrm{Z}\mathrm{n}}{-\mathrm{O}-\mathrm{L}\mathrm{i}}_{\mathrm{Z}\mathrm{n}};{\mathrm{V}}_{\mathrm{Z}\mathrm{n}}-\mathrm{O}{-\mathrm{L}\mathrm{i}}_{\mathrm{Z}\mathrm{n}}]$ complexes. However, no firm identification has been established. By integrating accurate perturbation models in a realistic Green’s function method, we have meticulously simulated the impurity vibrational modes of ${\mathrm{A}\mathrm{l}}_{\mathrm{Z}\mathrm{n}}$${(\mathrm{L}\mathrm{i}}_{\mathrm{Z}\mathrm{n}})$ and their bonding to form complexes with dopants as well as intrinsic defects. We strongly feel that these phonon features in doped ZnO will encourage spectroscopists to perform similar measurements to check our theoretical conjectures. Full article

The elevator light curtain is constrained by technical limitations in its infrared detection mechanism; thus, it is difficult to effectively identify the transparent material and elongated form of the object, which has become one of the main causes of abnormal elevator jamming accidents. To mitigate elevator accidents, we propose a novel visual segmentation method, PKNet (Prior Knowledge Network), specifically designed for detecting transparent and slender objects. We observe that the majority of cameras used in elevators are stationary, resulting in an inherently static background, while vision tasks primarily focus on detecting foreground objects. To this end, PKNet enhances the segmentation of dynamic foreground objects by incorporating prior knowledge of the static background and the characteristics of foreground objects. We also introduce ETAS-D, the first dataset designed for the segmentation of transparent and slender anomalous objects in elevator environments. This dataset consists of 4797 image frames, each with meticulously annotated masks of transparent and slender objects, captured from multiple viewpoints of 10 elevators. Extensive experimental results demonstrate that PKNet significantly outperforms existing methods in this domain. Furthermore, we propose a synthetic data generation workflow specifically designed for slender objects to enhance the model’s generalization ability and reliability. Full article

Money Art is a growing contemporary practice where artists transform banknotes into unique visual works. While conceptually powerful, these artworks present significant conservation challenges due to their fragile substrates and complex material compositions. This study investigates the degradation behaviour of UniPosca acrylic markers applied on zero-euro banknotes, drawing on the techniques of artist RichardHTT, and explores bio-based protective strategies suitable for their preservation. Laboratory samples were prepared to replicate the original artwork and subjected to accelerated ageing. A multi-analytical approach was employed, including multispectral imaging, Fourier trasform infrared (FTIR) and Raman spectroscopy, and scanning electron microscopy (SEM-EDS) colorimetric analysis. Thickness and adhesion properties were assessed with contact micrometry and peel tests, while wettability was evaluated through static contact angle measurements. Four biopolymer coatings, chitosan and chitosan–nanocellulose films with varying CNC concentrations, were evaluated for their transparency, mechanical stability, and compatibility with the substrate. Results showed that painted areas, especially those with blue and black pigments, experienced marked degradation, while, after coating application, samples demonstrated improved chromatic stability, hydrophobicity, and adhesion. Importantly, all coatings were fully removable via enzymatic cleaning with α-amylase, confirming their reversibility. This research highlights the potential of chitosan-based biocomposites as conservation materials for non-traditional artworks and contributes to developing tailored, reversible strategies for contemporary art preservation. Full article

Traditional nanoparticle aerogels suffer from inherent brittleness and thermal instability at elevated temperatures. In recent years, ceramic nanofiber aerogels, utilizing flexible nanofibers as structural units, have emerged as mechanically resilient alternatives with ultrahigh porosity (>90%). However, their thermal insulation capabilities are compromised by micron-scale pores (10–100 μm) and overdependence on ultralow density, which exacerbates mechanical fragility. This study pioneers a gas-phase self-assembly strategy to fabricate Si₃N₄ nanoparticle reinforced Si₃N₄ nanofiber aerogels (SNP-R-SNFA) with gradient pore architectures. By leveraging methyltrimethoxysilane/vinyltriethoxysilane composite aerogel (MVa) as a reactive template, we achieved spontaneous growth of Si₃N₄ nanofiber films (SNP-R-SNF) featuring nanoparticle-fiber interpenetration and porosity gradients. The microstructure formation mechanism of SNP-R-SNF was analyzed using field-emission scanning electron microscopy. Layer assembly and hot-pressing composite technology were employed to prepare the SNP-R-SNFA, which showed low density (0.033 g/cm³), exceptional compression resilience, insensitive frequency dependence of dielectric properties (ε′ = 2.31–2.39, tan δ < 0.08 across 8–18 GHz). Infrared imaging displayed backside 893 °C cooler than front, demonstrating superior insulation performance. This study not only provides material solutions for integrated electromagnetic wave-transparent/thermal insulation applications but more importantly establishes an innovative paradigm for enhancing the mechanical robustness of nanofiber-based aerogels. Full article