Search Results (1,084)

Electromagnetic interference (EMI) shielding materials are essential for ensuring the reliable operation of electronic devices and safeguarding human health, yet conventional metal-polymer materials are non-biodegradable, energy-intensive, and difficult to recycle. This study prepared a biodegradable paper-based shielding material; renewable cellulose filter paper was employed as the sole substrate, and graphene was integrated to construct an electromagnetic shielding network. A low-cost paper-based electromagnetic shielding preparation method was developed, and the performance of the material was analyzed in electromagnetic shielding applications. Samples were fabricated through a simple impregnation-evaporation-lamination process. It has a thickness of 1 mm for single layers and a maximum conductivity of 21.3 S/m. The influence of sample thickness on electromagnetic shielding in the X-band (8.2–12.4 GHz) was investigated, when the graphene filter cake loading reached 20 wt%, the SE_T values for triple-layer electromagnetic shielding papers reach 36 dB at 8.2 GHz and 33 dB at 12.4 GHz. A phone box for indoor environments and a card holder with anti-radio-frequency identification (RFID) functionality were designed. Furthermore, achievable design solutions for an EMI shielding wallpaper in medical and artistic installations were proposed. Full article

Greenly synthesised Ni-doped Ag nanoparticles utilising Caralluma umbellata root extracts, and an investigation into their optical properties, biological properties, and characterisation, is the focus of the study. Characterisation was performed using FTIR analysis, UV-Vis, X-ray diffraction, and field emission scanning electron microscopy. The synthesis of Ni-doped Ag nanoparticles was confirmed through UV-Vis spectroscopy, revealing a peak at 396 nm and a band gap energy of 3.24 eV. XRD analysis revealed a face-centred cubic structure with a crystallite size of 55.22 nm (as-prepared) and 18.56 nm (annealed at 200 °C). Reduction and capping were demonstrated by FTIR, as evidenced by the presence of phytochemicals. The Ag NPs demonstrated potent antibacterial activity against both Gram-positive and Gram-negative bacteria, with a minimal inhibitory concentration of 1.25 μg/mL observed against Streptococcus mutans. Their vigorous anti-oxidant activity, as well as in vitro anti-diabetic potential through alpha-amylase and alpha-glucosidase inhibition, also proves suitable for biomedical applications. Full article

We propose a strain-optimized design strategy for lattice-matched InAs_1−xSb_x/Al_1−yIn_ySb Type-I quantum wells (QWs) that emit across the near-to mid-infrared spectrum (2–5 µm). By combining elastic strain energy minimization with band offset calculations, we identify Type-I alignment for Sb contents (x ≤ 0.40) and In contents (0.10 < y ≤ 1). At the same time, Type-II dominates at higher Sb compositions (x ≥ 0.50). Using the transfer matrix method under the effective mass approximation, we demonstrate precise emission tuning via QW thickness (L_W) and compositional control, achieving a wavelength coverage of 2–5 µm with <5% strain-induced energy deviation. Our results provide a roadmap for high-efficiency infrared optoelectronic devices, addressing applications in sensing and communications technologies. Full article

In this study, we report a reproducible in situ photochemical method for the simultaneous synthesis of metallic and hybrid metal/metal oxide nanoparticles (NPs) within a UV–curable polymer matrix. A series of epoxy diacrylate-based formulations (BEA) was prepared, consisting of Epoxy diacrylate, Di(Ethylene glycol)ethyl ether acrylate (DEGEEA), and Phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (BAPO), which served as a Type I photoinitiator. These formulations were designed to enable the simultaneous photopolymerization and photoreduction of metal precursors at various Ag⁺/Co²⁺ ratios, resulting in nanocomposites containing in situ-formed Ag NPs, cobalt oxide NPs, and hybrid Ag–Co₃O₄ nanostructures. The photochemical, magnetic, and dielectric properties of the resulting nanocomposites were evaluated in comparison with those of the pure polymer using UV–Vis and Fourier Transform Infrared Spectroscopy (FT-IR), Photo-Differential Scanning Calorimetry (Photo-DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Impedance Analysis, and Vibrating Sample Magnetometry (VSM). Photo-DSC studies revealed that the highest conversion values were obtained for the BEA-Ag₁Co₁, BEA-Co, and BEA-Ag₁Co₂ samples, demonstrating that the presence of Co₃O₄ NPs enhances polymerization efficiency because of cobalt species participating in redox-assisted radical generation under UV irradiation, increasing the number of initiating radicals and leading to faster curing and higher final conversion. On the other hand, the Ag NPs, due to the SPR band formation at around 400 nm, compete with photoinitiator absorbance and result in a gradual decrease in conversion values. Crystal structures of the NPs were confirmed by XRD analyses. The dielectric and magnetic characteristics of the nanocomposites suggest potential applicability in energy-storage systems, electromagnetic interference mitigation, radar-absorbing materials, and related multifunctional electronic applications. Full article

Aluminum nitride (AlN) possesses an exceptional combination of high thermal conductivity and an ultra-wide band gap, rendering it highly attractive for electronic packaging and semiconductor substrate applications. In this study, surface chemical modification of AlN powders was performed employing low-molecular-weight organic acids, successfully yielding hydrolysis-resistant AlN powders. The underlying mechanisms responsible for the improved anti-hydrolysis performance imparted by both single organic acids and the composite acid were systematically investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM), characterization techniques. The results reveal that Oxalic acid within the concentration range of 0.25 M to 1.50 M partially inhibits the hydrolysis of aluminum nitride (AlN); however, hydrolysis products such as aluminum hydroxide are still formed. In the case of citric acid, a higher concentration leads to a stronger anti-hydrolysis effect on the modified AlN. No significant hydrolysis products were detected when the AlN sample was treated in a 1 M aqueous citric acid solution at 80 °C. The effectiveness of the organic acids in enhancing the hydrolysis resistance of AlN follows the order: composite acid (citric acid + oxalic acid) > citric acid > oxalic acid. Under the action of the composite acid, the AlN diffraction peaks exhibit the highest intensity. Furthermore, TEM observations reveal the formation of an amorphous protective layer on the surface, which contributes to the improved hydrolysis resistance. Analytical results confirmed that the surface modification process, mediated by citric acid, oxalic acid, or the composite acid, involved an esterification-like reaction between the surface hydroxyl groups on AlN and the chemical modifiers. This reaction led to the formation of a continuous protective coordination layer encapsulating the AlN particles, which serves as an effective diffusion barrier against water molecules, thereby significantly inhibiting the hydrolysis reaction. Full article

Accurate delineation of inland waterbodies is critical for applications such as hydrological monitoring, disaster response preparedness and response, and environmental management. While optical satellite imagery is hindered by cloud cover or low-light conditions, Synthetic Aperture Radar (SAR) provides consistent surface observations regardless of weather or illumination. This study introduces a deep learning-based ensemble framework for precise inland waterbody detection using high-resolution X-band Capella SAR imagery. To improve the discrimination of water from spectrally similar non-water surfaces (e.g., roads and urban structures), an 8-channel input configuration was developed by incorporating auxiliary geospatial features such as height above nearest drainage (HAND), slope, and land cover classification. Four advanced deep learning segmentation models—Proportional–Integral–Derivative Network (PIDNet), Mask2Former, Swin Transformer, and Kernel Network (K-Net)—were systematically evaluated via cross-validation. Their outputs were combined using a weighted average ensemble strategy. The proposed ensemble model achieved an Intersection over Union (IoU) of 0.9422 and an F1-score of 0.9703 in blind testing, indicating high accuracy. While the ensemble gains over the best single model (IoU: 0.9371) were moderate, the enhanced operational reliability through balanced Precision–Recall performance provides significant practical value for flood and water resource monitoring with high-resolution SAR imagery, particularly under data-constrained commercial satellite platforms. Full article

This study presents the design, optimization, and experimental validation of a dual-band dielectric monopole antenna. The proposed antenna structure consists of three concentric cylindrical dielectric layers, each with independently tunable permittivities and radii. This configuration allows the effective control of electromagnetic performance over distinct frequency bands. To determine the optimal geometric and material parameters, the bio-inspired Honey Bee Mating Optimization (HBMO) algorithm is employed. The optimization process simultaneously maximizes antenna gain and minimizes reflection coefficient in the X and Ku bands. A cost function incorporating both gain and impedance matching criteria is formulated to achieve well-balanced solutions. The final antenna prototype was fabricated using a fused deposition modeling (FDM)-based 3D printer, where the dielectric properties of each layer are adjusted through variable infill rates. Simulated and measured results confirm stable dual-band operation with reflection coefficients below −10 dB, while the maximum in-band realized gains reach approximately 6.6 dBi in the X-band and 7.1 dBi in the Ku-band. These findings demonstrate the effectiveness of the proposed optimization approach and validate the feasibility of using 3D-printed dielectric-loaded structures as an efficient solution for high-frequency and space-constrained communication systems. Full article

Poly(lactic acid) (PLA)-based nanocomposites containing a mixture of graphene nanoplatelets (GNP) and carbon nanotube (CNT) as hybrid fillers were prepared using a solution-assisted sonication process followed by melt processing. The effects of the filler dispersion on dielectric properties and microwave absorbing (MWA) performance were systematically investigated. Two ionic liquids (ILs), trihexyl-(tetra-decyl)phosphonium bis (trifluoromethanesulfonyl)imide (IL1) and 11-carboxyundecyl-triphenylphosphonium bromide (IL2), were employed as dispersing agents for the carbonaceous fillers. Incorporation of IL-treated fillers resulted in enhanced dielectric permittivity and improved MWA performance of the PLA composites. The MWA properties were evaluated in X- band and Ku-band. A minimum reflection loss (RL) of −34 dB and an effective absorption bandwidth (EAB) of 2.1 GHz were achieved for the composite containing GNP/CNT/IL2 (HB3) at a weight ratio of 2.5:0.5:0.5 wt% with one 3 mm thick layer. The superior performance of IL2 is attributed to π-π and π-cation interactions between its phenyl-containing cation and the carbonaceous fillers, as well as improved compatibility with the PLA matrix due to carboxyl groups. Additionally, three-layered composite structures, combining PLA/GNP as the outer layer with IL-assisted hybrid fillers in the core and PLA/CNT at the bottom layer, achieved an extended EAB of 4.5 GHz for GNP/HB2/CNT arrangement and 4.35 GHz for the GNP/HB3/CNT arrangement, driven by enhanced scattering and internal reflection of microwaves. These results demonstrate the potential of IL-assisted hybrid filler dispersion in PLA for developing biodegradable materials with multifunctional applications as charge storage capacitors and microwave absorbing materials for sustainable electronics. Full article

Green technologies are actively being used to produce nanosized zinc oxide, which is in demand for water purification processes to remove pollutants. Despite the success of the green synthesis of ZnO nanoparticles, no scientific approach exists for selecting plant extracts to produce nanoparticles with the desired properties. This study shows that the antioxidant activity of the plant extracts used is a key parameter influencing the properties of the resulting ZnO nanoparticles. This conclusion is based on the results of nanoparticle synthesis with the use of various plant extracts. The antioxidant activity of the extracts increases in the following order: plum–gooseberry–black currant–strawberry–sea buckthorn. The synthesized ZnO nanoparticles were characterized by UV–visible spectroscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The catalytic properties of ZnO nanoparticles were tested under the degradation of a synthetic methylene blue dye after exposure to UV light. We found that with an increase in the AOA of plant extracts, the size of the nanoparticles decreases, while their photocatalytic activity increases. The smallest (d = 13 nm), most uniform in size (polydispersity index 0.1), and most catalytically active ZnO nanoparticles with a small band gap (2.85 eV) were obtained using the sea buckthorn extract with the highest AOA, pH 10 of the reaction mixture and 0.1 M Zn(CH₃COO)₂∙2H₂O as a precursor salt. ZnO nanoparticles synthesized in the sea buckthorn extract demonstrated the highest dye photodegradation efficiency (96.4%) compared with other nanoparticles. The established patterns demonstrate the “antioxidant activity–size–catalytic activity” triad can be considered as a practical guide for obtaining ZnO nanoparticles of a given size and with given properties for environmental remediation applications. Full article

Many industrial sectors are concerned about microbiological contamination and the associated risk of microbiologically influenced corrosion (MIC). This applies in particular to the transmission and storage of fuels in the refining industry. Exceeding a certain level of these contaminants poses a serious risk to fuel quality and can cause storage and pipeline infrastructure corrosion. This situation requires an urgent evaluation of microorganism levels in the fuel to avert such detrimental consequences. Diesel fuels containing biofuel additives are particularly susceptible to these phenomena. Traditional detection methods are limited by low sensitivity, high costs, and long turnaround times, making them unsuitable for quick, on-site, and real-time detection and monitoring. A novel approach involves the application of microwave dielectric testing to quantify microbial load in diesel fuel. Microwave dielectric spectroscopy offers a non-destructive, label-free solution, providing rapid information on microorganism presence. Combined with chemometric techniques, it effectively estimates total microorganism counts in diesel fuel. Measurement in the X-band range (8.2–12.4 GHz) takes a few seconds. Calibration with known bacterial and fungal concentrations (10³ to 10⁷ CFU/mL) and principal component analysis (PCA) of the spectroscopic data allow for clear differentiation of contamination levels, categorizing them from acceptable to hazardous. The sensitivity limit of the proposed method corresponds to a bacterial concentration of 10³ CFU/mL. Full article

Zn_1−xFe_xO nanocomposites (NCs) with varying Fe concentrations (x = 0, 0.1, 0.2, 0.3, and 0.4) were effectively prepared using the hydrothermal approach, and their morphology, structural, optical, and magnetic properties were systematically analyzed. XRD analysis confirmed Fe doping reduced crystallinity and crystallite size. TEM images of Zn_1−xFe_xO NCs exhibited smaller and more agglomerated nanostructures compared to the pure ZnO NPs. Raman and XPS analyses indicated increased lattice disorder, oxygen vacancies, and the coexistence of Fe²⁺/Fe³⁺ species. UV–Vis spectra showed enhanced visible light absorption and a tunable band gap, while PL results reflected defect-induced emission shifts and quenching, associated with zinc vacancies, interstitials, and oxygen-related defects. Magnetic measurements revealed a transition from diamagnetism to ferromagnetic-like behavior at room temperature for Fe content x ≥ 0.2, with magnetization strongly dependent on doping level. These results highlight Zn_1−xFe_xO for advanced optoelectronic and spintronic applications. Full article

Due to the strong electronegativity of oxygen ions, the valence band maximum (VBM) that is derived from the O 2p orbital leads to strong localization, as well as further heavy hole mass and low hole mobility, which makes it extremely difficult to obtain high-conductivity p-type transparent conductive materials. Herein, we propose the strategy of multiple anions through the introduction of weaker electronegative nitrogen, in consideration of the delocalization on VBM, as well as the stability of octahedral anion cages. As such, first-principles calculations in the framework of density functional theory (DFT) are used for this work. Crystal structure prediction software USPEX (version 2023.0) was adopted to investigate the N-O appropriate ratio in CaTiO_3−xN_x (0 ≤ x ≤ 1) to balance the high transmission of light and highly favorable dispersion at the VBM. Furthermore, the p-type TCO performance of CaTiO_3-xN_x was evaluated based on the hole effective mass, hole mobility, and conductivity. The effectiveness of modulating p-type TCO through N-O multiple anions was also evaluated through defect formation energy and ionization energy. Ultimately, the construction of a CaTiO_3-xN_x/Si heterojunction and band alignment were considered for practical application. This approach attempts to boost the diversity of p-type perovskite-based TCOs and opens a new perspective for engineering and innovative material design for sustainable TCOs demand. 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

Cadmium sulfide is an important II-VI semiconductor known for its valuable photocatalytic properties ascribable to its band gap energy, which allows light absorption in the visible domain. Nonetheless, the application of cadmium sulfide in wastewater organic pollutant degradation is restricted due to its high toxicity to humans, soil, and marine life. To address this issue, we developed new composite materials by depositing CdS on a bentonite support in a 1:9 mass ratio to develop a photocatalyst with lower toxicity. In the first step, bentonite was activated using an aqueous HCl solution; for the deposition of CdS powder, we proposed the trituration method and compared it with chemical precipitation and hydrothermal synthesis, using thioacetamide as a sulfide ion source. The modified bentonite underwent characterization using X-ray diffraction, scanning electron microscopy, X-ray fluorescence, UV-Vis, and FTIR spectroscopy. The photocatalytic activity was tested in the degradation of Congo red (CR), a persistent diazo dye. The efficiency of removing CR with CdS–bentonite composites depended on the deposition method of CdS, and it was higher than that of pristine CdS and of only adsorption onto acid-activated bentonite. The photocatalytic degradation mechanism was estimated by the scavenger test using ethylenediaminetetraacetic acid disodium salt, ascorbic acid, ethanol, and silver nitrate as radical scavengers. Full article

In this present study, sodium- and strontium-modified bismuth titanate—Bi_0.5Na_0.5TiO₃ (BNT) and Bi_0.5Sr_0.5TiO₃ (BST)—were synthesized using the auto-combustion technique with citric acid (C₆H₈O₇) and glycine (C₂H₅NO₂) as fuels in an optimized ratio of 1.5:1. The resulting powders were characterized using X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, UV–Visible diffuse reflectance spectroscopy (DRS), and Fourier-transform infrared (FT-IR) spectroscopy. The electrical behavior of the samples was studied using an LCR meter. XRD analysis confirmed the formation of a single-phase perovskite structure with average crystallite sizes of 18.60 nm for BNT and 22.03 nm for BST, attributed to the difference in ionic radii between Na⁺ and Sr²⁺. An increase in crystallite size was accompanied by a corresponding increase in lattice parameters and unit-cell volume. The Williamson–Hall analysis further validated the strain-size contributions. EDX (Energy-Dispersive X-ray analysis) results confirmed successful incorporation of Na⁺ and Sr²⁺ without detectable impurity phases. Optical studies revealed distinct absorption peaks at 341 nm for BNT and 374 nm for BST, and the optical bandgap (E_g), calculated using Tauc’s relation, was found to be 2.6 eV and 2.0 eV, respectively. FT-IR spectra exhibited characteristic Ti-O vibrational bands in the range of 420–720 cm⁻¹, consistent with the perovskite structure. For electrical characterization, the powders were pelletized under 3-ton pressure and sintered at 1000 °C for 3 h. The dielectric constant (ε_r), dielectric loss (tan δ), and ac conductivity (σ) of both samples increased with frequency. The combined structural, optical, and electrical results indicate that the optimized compositions of BNT and BST possess properties suitable for use in capacitors and other energy-storage applications. Full article