Search Results (13,801)

W-doped ZnO (WZO) films were deposited on glass substrates by using RF magnetron sputtering at different substrate bias voltages, and the relationships between microstructure and optical and electrical properties were investigated. The results revealed that the deposition rate of WZO films first decreased from 8.8 to 7.1 nm/min, and then increased to 11.5 nm/min with the increase in bias voltage. After applying a bias voltage to the substrate, the bombardment effect of sputtered ions was enhanced, and the films transformed from a smooth surface into a compact and rough surface. All the films exhibited a hexagonal wurtzite structure with a strong (002) preferred orientation and grew along the c-axis direction. When the bias voltage increased, both the residual stress and lattice parameter of the films gradually increased, and the maximum grain size of 43.4 nm was achieved at −100 V. When the bias voltage was below −300 V, all the films exhibited a high average transmittance of ~90% in the visible light region. As the bias voltage increased, the sheet resistance and resistivity of the films initially decreased and then gradually increased. The highest F_OM of 5.8 × 10⁻⁴ Ω⁻¹ was achieved at −100 V, possessing the best comprehensive photoelectric properties. Full article

Dichlorvos (2,2-dichlorovinyl dimethyl phosphate, DDVP) is a highly toxic organophosphorus insecticide, and its persistence in air, water, and soil poses potential threats to human health and ecosystems. Covalent triazine frameworks (CTFs), with their sufficient visible-light harvesting capacity, ameliorated charge separation, and exceptional redox ability, have emerged as promising candidates for the photocatalytic degradation of DDVP. Nevertheless, pure CTFs lack effective oxidative active sites, resulting in elevated reaction energy barriers during the photodegradation of DDVP. In this work, density functional theory (DFT) calculations were employed to investigate the impact of various oxygen-containing acid groups (-COOH, -HSO₃, -H₂PO₃) on DDVP photodegradation performance. First, simulations of the structure and optical properties of modified CTFs reveal that oxygen-containing acid groups induce surface distortion and result in a redshift in the absorption edge. Subsequently, analysis of the density of states, frontier molecular orbitals, surface electrostatic potential, work function, and dipole moment demonstrates that oxygen-containing acid groups enhance CTF polarization, facilitate charge separation, and ameliorate their oxidative capability. Additionally, the free-energy diagram of DDVP degradation uncovers that oxygen-containing acid groups lower the energy barrier by elevating the adsorption and activation capability of DDVP. Notably, -H₂PO₃ presents optimal potential for the photodegradation of DDVP by unique electronic structure and activation capability. This work offers a valuable reference for the development of oxygen-containing acid CTF-based photocatalysts applied in degrading toxic organophosphate pesticides. Full article

In this study, we experimentally demonstrate a PPLN-based free-space to SMF (single-mode fiber) conversion system capable of efficient long-wavelength down-conversion from 518 nm, optimized for minimal loss in highly turbid water, to 1540 nm, which is ideal for low-loss transmission in standard SMF. Leveraging the nonlinear optical properties of periodically poled lithium niobate (PPLN), we achieve a wavelength conversion efficiency of 1.6% through difference frequency generation while maintaining a received optical signal-to-noise ratio of 10.4 dB. Our findings underscore the potential of integrating PPLN-based wavelength conversion with fiber optic networks, offering a viable solution for next-generation optical sensor systems that demand real-time, low-latency, and reliable data transmission. This work represents a significant advancement in developing robust and efficient optical sensor technologies, addressing the challenges associated with long-distance transmission and broad-linewidth light sources in optical remote sensing applications. Full article

This research aims to analyze the improvement in the photocatalytic properties of ZnO nanoparticles by incorporating Gd. In order to understand the influence of incorporating Gd into the ZnO matrix, the photocatalytic activity of the material is compared at various Gd concentrations. Different doping concentrations of Gd ranging from 0 to 0.075 are incorporated into ZnO and the synthesized ZnO-Gd nanocomposites are investigated using structural, morphological, and optical analyses using XRD, SEM, and UV-vis spectroscopy, respectively. The photocatalytic performance of the synthesized ZnO-Gd nanocomposites is determined via the degradation of organic contaminants under visible light. Regarding the latter, the results suggest that photocatalytic efficiency increases with increasing Gd doping levels up to an optimal doping concentration. The enhancement of the photocatalytic performance of Gd-doped ZnO is explained, along with the mechanism related to the availability of new pathways for charge carrier recombination. Among all of them, the 0.075 Gd-doped ZnO catalyst exhibits the highest photocatalytic activity which degrades 89% of MB dye after being irradiated with UV light for 120 min. However, pure ZnO degrades only 40% of MB dye within the same testing conditions. In closing, this work confirms the applicability of Gd-doped ZnO nanocomposites as photocatalysts in cleaning up the environment and in wastewater treatment. Full article

To further study the electro-optical modulation characteristics of LiNbO₃ crystals and analyze their modulation performance, a method for studying the modulation characteristics of LiNbO₃ crystals, based on the three-dimensional ray tracing method, is introduced. With the help of the refractive index ellipsoidal theory, the optical properties of LiNbO₃ crystals under the influence of the Pockels effect are systematically investigated. The research results show that the optical properties of LiNbO₃ crystals under the action of an external electric field can be divided into two cases: the crystal optical axis is parallel to the clear light direction, and the crystal optical axis is perpendicular to the clear light direction. Subsequently, starting from Maxwell’s equation and the matter equation, the analytical expressions of optical parameters such as refractive index, wave vector, light vector, optical path, and phase delay in electro-optical crystals are derived. Finally, the propagation law of LiNbO₃ crystals when the light is incident in any direction, i.e., when the optical axis of the crystal is parallel to the clear direction and perpendicular to the clear direction, and the light intensity and field of view of the LiNbO₃ crystal for electro-optical modulation are discussed. Full article

Arbitrarily designed flat optics directly manipulate the light wavefront to reproduce complex optical functions, enabling more compact optical assemblies and microsystem integration. Phase-shifting micro-optical devices rely on locally tailoring the optical path length of the wavefront through binary or multilevel surface relief micro- and nanostructures. Considering the resolution and tolerances of the production processes and the optical properties of the substrate and coating materials is crucial for designing robust multilevel diffractive flat optics. In this work, we evaluate the impact of the grayscale laser lithography resolution and geometry constraints on the efficiency of surface-relief diffractive lenses, and we analyze the process parameter space that limit lens performance. We introduce a spectral bandwidth metric to help evaluate the broad-spectrum performance of different materials. We simulate and experimentally observe that the diffractive focusing is dominated by the periodic wavelength-dependent phase discontinuities arising in the profile transitions of multilevel diffractive lenses. Full article

Clear aligners have transformed orthodontic care by providing an aesthetic, removable alternative to traditional braces. However, their significant environmental footprint, contributing to approximately 15,000 tons of plastic waste annually, poses a critical challenge. To address this issue, advancements in 4D printing have introduced “smart” aligners with shape memory properties, enabling reshaping and reducing the number of aligners required per treatment. This study focuses on ClearX aligners, an innovative 4D-printed solution aimed at extending usage duration and minimizing environmental impact. Using a comprehensive suite of tests, including morphological, optical, and mechanical evaluations conducted via scanning electron microscopy, UV-Vis spectroscopy, infrared spectroscopy, and bending and strain assessments, we evaluated the optical and mechanical stability of the ClearX material before and after thermal activation. Our results demonstrate that ClearX aligners retain their structural and functional properties after reshaping. Temporary changes in transparency, observed only under prolonged treatment durations exceeding manufacturer recommendations, are fully reversible within 12 h and do not compromise the aligner’s usability. These findings support the potential of ClearX aligners to effectively combine patient-centered, high-quality orthodontic care with sustainable practices. Full article

By combining molecular dynamics (MD) simulations and density functional theory (DFT), the influence of dye structure on the optical modulation properties of negative-mode guest–host liquid crystal (GHLC) systems was systematically investigated. Firstly, the reliability of the simulation method was validated by comparing the performance parameters of the GHLC system obtained from simulations with those from experimental results. Subsequently, a series of guest dye molecules, along with their mixtures with negative dielectric anisotropy mesogens, were designed and analyzed. This exploration focused on how variations in dye terminal chain lengths, substitution positions, and substituent group properties affect dye molecular geometry, dye alignment within the host, transition dipole orientation, absorption spectra, and electronic excitation properties. Our findings suggest that dye molecules with a flexible terminal chain substitution of five carbon atoms, positioned at the 2 and 6 locations on the anthraquinone core, exhibit higher order parameters, favorable for enhancing dichroic performance. Moreover, introducing different α-substituents further influences the dye orientation and electronic behavior within the host. These results highlight that structural modifications of anthraquinone-based dyes allow for the design of high-dichroic-ratio materials with customized absorption properties. Overall, our results provide a beneficial understanding of the structure–property relation in GHLC systems, offering valuable guidance for designing high-performance dye molecules and advanced optoelectronic materials in future research. Full article

The new chiral and configurationally stable cyclopentadienyl amidinate (CPAM) hafnium complexes, (R_C, R_Hf)-2 and (S_C, S_Hf)-3, have been obtained in enantio- and diastereomerically pure form. Upon activation with the borate co-initiator, [PhNHMe₂][B(C₆F₅)₄] (B1), 2 and 3 can serve as pre-initiators for the enantioselective living coordinative polymerization (LCP) and living coordinative chain transfer polymerization (LCCTP) of 1,5-hexadiene to provide optically active poly (methylene-1,3-cyclopentane) (PMCP) and end-group-functionalized PMCP (x-PMCP) in scalable quantities, respectively. ¹³C NMR stereochemical microstructural analyses reveal the role of ligand directing effects for the two-step propagation mechanism of 1,2-migratory insertion/ring-closing cyclization and structure/property relationships for these new PMCP and x-PMCP materials. Full article

This research follows closely previous findings in flow characteristics and phenomena that take place in the piston ring and cylinder liner interface during motoring and firing engine operation, and also compares results between different optical engine set-ups. Cavitation visualisation in a simulating lubrication single-ring test rig and oil transport and cavitation visualisation in custom made cylinder assemblies of optical engines are the tools used to quantify the transport process under the piston ring and cylinder liner. Simplification of the interface is an essential technique that enhances the researcher’s confidence in results interpretation. Engine complexity and severe oil starvation are impeding the analysis of the experimental results. Visualisation experiments constitute an effective way to test various lubricant types and assess their overall performance characteristics, including their properties and cavitation behaviour. The repeatability of the visualisation method establishes the parametric study effects and offers valuable experimental results. As a further step towards the lubricant composition effect, a link between the lubricant formulation and the operating conditions could be established as the oil performance is assessed with a view to its transport behaviour. Image processing is used to quantify the impact of cavitation on piston ring lubrication in conjunction with varied operating and lubricant parameters. The characteristics of the lubricant and the working environment have an impact on these types of cavities. Viscosity, cavitation, oil film thickness (OFT), lubricant shear-thinning characteristics and friction are all linked. Full article

Biomass valorization and bio-based material development are of major research interest following the spirit of the circular economy. Aloe vera cultivation is a widespread agricultural activity oriented toward supplement production because of its well-known antioxidant and antimicrobial properties. Aloe vera juice production also produces a large amount of biomass byproducts that are usually landfilled. On the other hand, cellulose nanocrystals are widely used in several applications, such as biomaterials, bio-compatible polymers, nanocomposites, food packaging, medicines, cosmetics, and sensors, due to their unique physical, mechanical, optical, electrical, and healing properties as well as their compatibility with biological tissues. This study introduces a novel approach combining the microwave-assisted extraction (MAE) of cellulose from this residue with the subsequent isolation of cellulose nanocrystals (CNCs). The MAE process, which exhibits a rapid heating and penetrating ability, was optimized to maximize the cellulose yield under various conditions (microwave power, solvent ratio, and time). Analysis using FTIR, XRD, SEM, and DMA indicated that isolated pure cellulose nanocrystals and a stable PVA–CNC porous hydrogel network were produced. The PVA–CNC hydrogel was synthesized to enable the formation of a semi-crystalline network that imparts the material with enhanced mechanical properties. Both final products of this study could potentially be used for various applications. Full article

Chiral molecules are ubiquitous in nature and biological systems, where the unique optical and physical properties of chiral nanoparticles are closely linked to their shapes. Synthesizing chiral plasmonic nanomaterials with precise structures and tunable sizes is essential for exploring their applications. This study presents a method for growing three-dimensional chiral gold nanoflowers (Au NFs) derived from trisoctahedral (TOH) nanocrystals using D-cysteine and L-cysteine as chiral inducers. By employing a two-step seed-mediated growth approach, stable chiral Au nanoparticles with customizable sizes, shapes, and optical properties were produced by adjusting the Au nanosphere (Au NP) seed concentration and cysteine dosage. These nanoparticles exhibited optical activity in both the visible and near-infrared regions, with a maximum anisotropy factor (g-factor) of 0.024. Furthermore, the PEG-modified chiral Au NFs demonstrated excellent biocompatibility. This approach provides a precise method for geometrically controlling the design of three-dimensional chiral nanomaterials, holding great potential for biomedical applications. Full article

Ti and Ti6Al4V alloy are extensively utilized in structural parts in engineering applications and the production of medical implants due to their excellent mechanical properties, lightweight, and high corrosion resistance. This study comprehensively evaluates their corrosion behavior in three challenging aquatic environments: brackish water, seawater, and seawater bittern. Utilizing open circuit potential (E_OC) measurements with polarization techniques (linear and potentiodynamic) and electrochemical impedance spectroscopy (EIS) measurements, the research highlights distinct environmental influences on corrosion performance. Notably, Ti and Ti6Al4V alloy demonstrated exceptional stability with the highest polarization resistance and lowest corrosion current in brackish water, while seawater bittern presented the most demanding condition for Ti6Al4V. Additionally, the analysis of the electrode surfaces after polarization measurements using optical microscopy, optical profilometry, and SEM/EDS tests revealed minor damage, indicating the high corrosion resistance of these materials. This study advances the understanding of Ti and Ti6Al4V alloy performance in diverse environments and offers valuable insights for optimizing their use in harsh aquatic conditions, particularly for applications requiring durability and longevity. Full article

Phenoxazine, as an organic-small-molecule chromophore, has attracted much attention for its potential electrochromic applications recently. To develop appealing materials, phenoxazine chromophores were introduced at the N-position of carbazole–thiophene pigment, yielding two novel monomers (DTCP and DDCP), whose chemical structures were characterized by NMR, HRMS and FTIR. The results of the optical property study indicate that little influence could be observed in the presence of the phenoxazine chromophore. Corresponding polymer films on the surface of an ITO/glass electrode were obtained through electropolymerization. The electrochemical features displayed were various due to the introduction of the phenoxazine group. The spectroelectrochemical results demonstrate that the color of the polymer films could be changed. Compared with the PDDC films, the PDDCP films exhibited three different colors (tangerine, green and purple colors) in different redox states, which could be attributed to the synergistic effect between the carbazole–thiophene conjugate chain and the phenoxazine group. Moreover, fast switching time could be seen due to the presence of the phenoxazine chromophore. This study could provide a reference for obtaining high-performance electrochromic materials. Full article

Fluorescence is a remarkable property exhibited by many chemical compounds and biomolecules. Fluorescence has revolutionized analytical and biomedical sciences due to its wide-ranging applications in analytical and diagnostic tools of biological and environmental importance. Fluorescent molecules are frequently employed in drug delivery, optical sensing, cellular imaging, and biomarker discovery. Cancer is a global challenge and fluorescence agents can function as diagnostic as well as monitoring tools, both during early tumor progression and treatment monitoring. Many fluorescent compounds can be found in their natural form, but recent developments in synthetic chemistry and molecular biology have allowed us to synthesize and tune fluorescent molecules that would not otherwise exist in nature. Naturally derived fluorescent compounds are generally more biocompatible and environmentally friendly. They can also be modified in cost-effective and target-specific ways with the help of synthetic tools. Understanding their unique chemical structures and photophysical properties is key to harnessing their full potential in biomedical and analytical research. As drug discovery efforts require the rigorous characterization of pharmacokinetics and pharmacodynamics, fluorescence-based detection accelerates the understanding of drug interactions via in vitro and in vivo assays. Herein, we provide a review of natural products and synthetic analogs that exhibit fluorescence properties and can be used as probes, detailing their photophysical properties. We have also provided some insights into the relationships between chemical structures and fluorescent properties. Finally, we have discussed the applications of fluorescent compounds in biomedical science, mainly in the study of tumor and cancer cells and analytical research, highlighting their pivotal role in advancing drug delivery, biomarkers, cell imaging, biosensing technologies, and as targeting ligands in the diagnosis of tumors. Full article