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Search Results (1,299)

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Keywords = dielectric change

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22 pages, 3520 KiB  
Article
Cellulose Ether/Citric Acid Systems Loaded with SrTiO3 Nanoparticles with Solvent-Tailored Features for Energy-Related Technologies
by Raluca Marinica Albu, Mihaela Iuliana Avadanei, Lavinia Petronela Curecheriu, Gabriela Turcanu, Iuliana Stoica, Marius Soroceanu, Daniela Rusu, Cristian-Dragos Varganici, Victor Cojocaru and Andreea Irina Barzic
Molecules 2025, 30(15), 3271; https://doi.org/10.3390/molecules30153271 - 5 Aug 2025
Abstract
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 [...] Read more.
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
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15 pages, 3571 KiB  
Article
Thermal Modulation of Photonic Spin Hall Effect in Vortex Beam Based on MIM-VO2 Metasurface
by Li Luo, Jiahui Huo, Yuanyuan Lv, Jie Li, Yu He, Xiao Liang, Sui Peng, Bo Liu, Ling Zhou, Yuxin Zou, Yuting Wang, Jingjing Bian and Yuting Yang
Surfaces 2025, 8(3), 55; https://doi.org/10.3390/surfaces8030055 - 3 Aug 2025
Viewed by 31
Abstract
The photon spin Hall effect (PSHE) arises from the spin–orbit interaction of light. Metasurfaces enable precise control over the PSHE through their influence. Using electromagnetic simulations as its foundation, this work engineers a metal–insulator–metal (MIM) metasurface for generating vortex beams in the near-infrared [...] Read more.
The photon spin Hall effect (PSHE) arises from the spin–orbit interaction of light. Metasurfaces enable precise control over the PSHE through their influence. Using electromagnetic simulations as its foundation, this work engineers a metal–insulator–metal (MIM) metasurface for generating vortex beams in the near-infrared band, targeting enhanced modulation of the PSHE. Electromagnetic simulations embed vanadium dioxide (VO2)—a thermally responsive phase-change material—within the MIM metasurface architecture. Numerical evidence confirms that harnessing VO2’s insulator–metal-transition-mediated optical switching dynamically tailors spin-dependent splitting in the illuminated MIM-VO2 hybrid, thereby achieving a significant amplification of the PSHE displacement. Electromagnetic simulations determine the reflection coefficients for both VO2 phase states in the MIM-VO2 structure. Computed spin displacements under vortex beam incidence reveal that VO2’s phase transition couples to the MIM’s top metal and dielectric layers, modifying reflection coefficients and producing phase-dependent PSHE displacements. The simulation results show that the displacement change of the PSHE before and after the phase transition of VO2 reaches 954.7 µm, achieving a significant improvement compared with the traditional layered structure. The dynamic modulation mechanism of the PSHE based on the thermal–optical effect has been successfully verified. Full article
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15 pages, 3792 KiB  
Article
Polarization Characteristics of a Metasurface with a Single via and a Single Lumped Resistor for Harvesting RF Energy
by Erik Madyo Putro, Satoshi Yagitani, Tomohiko Imachi and Mitsunori Ozaki
Appl. Sci. 2025, 15(15), 8561; https://doi.org/10.3390/app15158561 (registering DOI) - 1 Aug 2025
Viewed by 94
Abstract
A square patch metasurface is designed, simulated, fabricated, and experimentally tested to investigate polarization characteristics quantitatively. The metasurface consists of one layer unit cell in the form of a square patch with one via and a lumped resistor, which is used for harvesting [...] Read more.
A square patch metasurface is designed, simulated, fabricated, and experimentally tested to investigate polarization characteristics quantitatively. The metasurface consists of one layer unit cell in the form of a square patch with one via and a lumped resistor, which is used for harvesting RF (radio frequency) energy. FR4 dielectric is used as a substrate supported by a metal ground plane. Polarization-dependent properties with specific surface current patterns and voltage dip are obtained when simulating under normal incidence of a plane wave. This characteristic results from changes in surface current conditions when the polarization angle is varied. A voltage dip appears at a specific polarization angle when the surface current pattern is symmetrical. This condition occurs when the position of the lumped resistor from the center of the patch is perpendicular to the linearly polarized incident electric field. A couple of 10 × 10 arrays with different resistor positions are fabricated and tested. The experimental results are in good agreement with the simulated results. The proposed design demonstrates a symmetric unit cell structure with one via and a resistor that exhibits polarization-dependent behavior for linear polarization. An asymmetric patch design is explored through both simulation and measurement to mitigate polarization dependence by suppressing the dip behavior, albeit at the expense of reduced absorption efficiency. This study provides a complete polarization analysis for both symmetric and asymmetric patch metasurfaces with a single via and a single lumped resistor, and introduces a predictive relation between the position of the resistor relative to the center of the patch and the resulting voltage dip behavior. Full article
(This article belongs to the Special Issue Electromagnetic Waves: Applications and Challenges)
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19 pages, 618 KiB  
Article
Application of Microwaves to Reduce Checking in Low-Fat Biscuits: Impact on Sensory Characteristics and Energy Consumption
by Raquel Rodríguez, Xabier Murgui, Yolanda Rios, Eduardo Puértolas and Izaskun Pérez
Foods 2025, 14(15), 2693; https://doi.org/10.3390/foods14152693 - 30 Jul 2025
Viewed by 173
Abstract
The use of microwaves (MWs) has been proposed as an energy-efficient method for reducing checking. Along with understanding moisture distribution, it is essential to consider structural characteristics to explain how MWs reduce checking. The influence of MWs on these characteristics depends on the [...] Read more.
The use of microwaves (MWs) has been proposed as an energy-efficient method for reducing checking. Along with understanding moisture distribution, it is essential to consider structural characteristics to explain how MWs reduce checking. The influence of MWs on these characteristics depends on the food matrix’s dielectric and viscoelastic properties, which vary significantly between fresh and pre-baked dough. This study investigates the effects of MW treatment applied before (MW-O) or after conventional oven baking (O-MW) on low-fat biscuits that are prone to checking. Color (CIELab), thickness, moisture content and distribution, checking rate, texture, sensory properties, energy consumption and baking time were analyzed. The findings suggest that MWs reduce checking rate by eliminating internal moisture differences, while also changing structural properties, as evidenced by increased thickness and hardness. MW-O eliminated checking (control samples showed 100%) but negatively affected color, texture (increased hardness and breaking work), and sensory quality. The O-MW checking rate (3.41%) was slightly higher than in MW-O, probably due to the resulting different structural properties (less thickness, less hardness and breaking work). O-MW biscuits were the most preferred by consumers (54.76% ranked them first), with color and texture close to the control samples. MW-O reduced total energy consumption by 16.39% and baking time by 25.00%. For producers, these improvements could compensate for the lower biscuit quality. O-MW did not affect energy consumption but reduced baking time by 14.38%. The productivity improvement, along with the reduction in checking and the satisfactory sensory quality, indicates that O-MW could be beneficial for the bakery sector. Full article
(This article belongs to the Special Issue Cereal Processing and Quality Control Technology)
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19 pages, 3671 KiB  
Article
Sustainable Benzoxazine Copolymers with Enhanced Thermal Stability, Flame Resistance, and Dielectric Tunability
by Thirukumaran Periyasamy, Shakila Parveen Asrafali and Jaewoong Lee
Polymers 2025, 17(15), 2092; https://doi.org/10.3390/polym17152092 - 30 Jul 2025
Viewed by 292
Abstract
Benzoxazine resins are gaining attention for their impressive thermal stability, low water uptake, and strong mechanical properties. In this work, two new bio-based benzoxazine monomers were developed using renewable arbutin: one combined with 3-(2-aminoethylamino) propyltrimethoxysilane (AB), and the other with furfurylamine (AF). Both [...] Read more.
Benzoxazine resins are gaining attention for their impressive thermal stability, low water uptake, and strong mechanical properties. In this work, two new bio-based benzoxazine monomers were developed using renewable arbutin: one combined with 3-(2-aminoethylamino) propyltrimethoxysilane (AB), and the other with furfurylamine (AF). Both were synthesized using a simple Mannich-type reaction and verified through FT-IR and 1H-NMR spectroscopy. By blending these monomers in different ratios, copolymers with adjustable thermal, dielectric, and surface characteristics were produced. Thermal analysis showed that the materials had broad processing windows and cured effectively, while thermogravimetric testing confirmed excellent heat resistance—especially in AF-rich blends, which left behind more char. The structural changes obtained during curing process were monitored using FT-IR, and XPS verified the presence of key elements like carbon, oxygen, nitrogen, and silicon. SEM imaging revealed that AB-based materials had smoother surfaces, while AF-based ones were rougher; the copolymers fell in between. Dielectric testing showed that increasing AF content raised both permittivity and loss, and contact angle measurements confirmed that surfaces ranged from water-repellent (AB) to water-attracting (AF). Overall, these biopolymers (AB/AF copolymers) synthesized from arbutin combine environmental sustainability with customizability, making them strong candidates for use in electronics, protective coatings, and flame-resistant composite materials. Full article
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19 pages, 590 KiB  
Review
Comprehensive Review of Dielectric, Impedance, and Soft Computing Techniques for Lubricant Condition Monitoring and Predictive Maintenance in Diesel Engines
by Mohammad-Reza Pourramezan, Abbas Rohani and Mohammad Hossein Abbaspour-Fard
Lubricants 2025, 13(8), 328; https://doi.org/10.3390/lubricants13080328 - 29 Jul 2025
Viewed by 331
Abstract
Lubricant condition analysis is a valuable diagnostic tool for assessing engine performance and ensuring the reliable operation of diesel engines. While traditional diagnostic techniques—such as Fourier transform infrared spectroscopy (FTIR)—are constrained by slow response times, high costs, and the need for specialized personnel. [...] Read more.
Lubricant condition analysis is a valuable diagnostic tool for assessing engine performance and ensuring the reliable operation of diesel engines. While traditional diagnostic techniques—such as Fourier transform infrared spectroscopy (FTIR)—are constrained by slow response times, high costs, and the need for specialized personnel. In contrast, dielectric spectroscopy, impedance analysis, and soft computing offer real-time, non-destructive, and cost-effective alternatives. This review examines recent advances in integrating these techniques to predict lubricant properties, evaluate wear conditions, and optimize maintenance scheduling. In particular, dielectric and impedance spectroscopies offer insights into electrical properties linked to oil degradation, such as changes in viscosity and the presence of wear particles. When combined with soft computing algorithms, these methods enhance data analysis, reduce reliance on expert interpretation, and improve predictive accuracy. The review also addresses challenges—including complex data interpretation, limited sample sizes, and the necessity for robust models to manage variability in real-world operations. Future research directions emphasize miniaturization, expanding the range of detectable contaminants, and incorporating multi-modal artificial intelligence to further bolster system robustness. Collectively, these innovations signal a shift from reactive to predictive maintenance strategies, with the potential to reduce costs, minimize downtime, and enhance overall engine reliability. This comprehensive review provides valuable insights for researchers, engineers, and maintenance professionals dedicated to advancing diesel engine lubricant monitoring. Full article
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18 pages, 3095 KiB  
Article
Investigating Seed Germination, Seedling Growth, and Enzymatic Activity in Onion (Allium cepa) Under the Influence of Plasma-Treated Water
by Sabnaj Khanam, Young June Hong, Eun Ha Choi and Ihn Han
Int. J. Mol. Sci. 2025, 26(15), 7256; https://doi.org/10.3390/ijms26157256 - 27 Jul 2025
Viewed by 323
Abstract
Seed germination and early seedling growth are pivotal stages that define crop establishment and yield potential. Conventional agrochemicals used to improve these processes often raise environmental concerns, highlighting the need for sustainable alternatives. In this study, we demonstrated that water treated with cylindrical [...] Read more.
Seed germination and early seedling growth are pivotal stages that define crop establishment and yield potential. Conventional agrochemicals used to improve these processes often raise environmental concerns, highlighting the need for sustainable alternatives. In this study, we demonstrated that water treated with cylindrical dielectric barrier discharge (c-DBD) plasma, enriched with nitric oxide (NO) and reactive nitrogen species (RNS), markedly enhanced onion (Allium cepa) seed germination and seedling vigor. The plasma-treated water (PTW) promoted rapid imbibition, broke dormancy, and accelerated germination rates beyond 98%. Seedlings irrigated with PTW exhibited significantly increased biomass, root and shoot length, chlorophyll content, and antioxidant enzyme activities, accompanied by reduced lipid peroxidation. Transcriptomic profiling revealed that PTW orchestrated a multifaceted regulatory network by upregulating gibberellin biosynthesis genes (GA3OX1/2), suppressing abscisic acid signaling components (ABI5), and activating phenylpropanoid metabolic pathways (PAL, 4CL) and antioxidant defense genes (RBOH1, SOD). These molecular changes coincided with elevated NO2 and NO3 levels and finely tuned hydrogen peroxide dynamics, underpinning redox signaling crucial for seed activation and stress resilience. Our findings establish plasma-generated NO-enriched water as an innovative, eco-friendly technology that leverages redox and hormone crosstalk to stimulate germination and early growth, offering promising applications in sustainable agriculture. Full article
(This article belongs to the Special Issue Plasma-Based Technologies for Food Safety and Health Enhancement)
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26 pages, 5031 KiB  
Article
Insulation Condition Assessment of High-Voltage Single-Core Cables Via Zero-Crossing Frequency Analysis of Impedance Phase Angle
by Fang Wang, Zeyang Tang, Zaixin Song, Enci Zhou, Mingzhen Li and Xinsong Zhang
Energies 2025, 18(15), 3985; https://doi.org/10.3390/en18153985 - 25 Jul 2025
Viewed by 166
Abstract
To address the limitations of low detection efficiency and poor spatial resolution of traditional cable insulation diagnosis methods, a novel cable insulation diagnosis method based on impedance spectroscopy has been proposed. An impedance spectroscopy analysis model of the frequency response of high-voltage single-core [...] Read more.
To address the limitations of low detection efficiency and poor spatial resolution of traditional cable insulation diagnosis methods, a novel cable insulation diagnosis method based on impedance spectroscopy has been proposed. An impedance spectroscopy analysis model of the frequency response of high-voltage single-core cables under different aging conditions has been established. The initial classification of insulation condition is achieved based on the impedance phase deviation between the test cable and the reference cable. Under localized aging conditions, the impedance phase spectroscopy is more than twice as sensitive to dielectric changes as the amplitude spectroscopy. Leveraging this advantage, a multi-parameter diagnostic framework is developed that integrates key spectral features such as the first phase angle zero-crossing frequency, initial phase, and resonance peak amplitude. The proposed method enables quantitative estimation of aging severity, spatial extent, and location. This technique offers a non-invasive, high-resolution solution for advanced cable health diagnostics and provides a foundation for practical deployment of power system asset management. Full article
(This article belongs to the Section F: Electrical Engineering)
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16 pages, 5533 KiB  
Article
P-2B Co-Doping Effects of the Electronic and Optical Properties of Diamond: A First-Principles Study Based on the HSE06 Generalized Function
by Weiyin Li and Meng Wang
Crystals 2025, 15(8), 678; https://doi.org/10.3390/cryst15080678 - 25 Jul 2025
Viewed by 243
Abstract
In the present study, the electronic structure and optical properties of P-2B co-doped diamond have been analyzed using first-principles calculations based on HSE06 generalized functions. Of the 15 complexes that we considered, the five most stable structures—BCPCB system, PCCBCB system, PCBCCB system, PCBBCB [...] Read more.
In the present study, the electronic structure and optical properties of P-2B co-doped diamond have been analyzed using first-principles calculations based on HSE06 generalized functions. Of the 15 complexes that we considered, the five most stable structures—BCPCB system, PCCBCB system, PCBCCB system, PCBBCB system, and PBCB system were identified and studied, and the bandgap was found to reduce from 5.496 eV of intrinsic diamond to 3.610, 3.210, 3.210, 3.210, and 3.250 eV, respectively. Notably, the BCPCB-doped system exhibited significant changes in optical properties: the static dielectric constant increased from 4.18 to over 45, the real part of the conductivity showed a new peak at 2.0 eV (11) with a red-shifted spectrum, the light absorption edge was red-shifted, the static refractive index rose from 2 to 25, and a pronounced peak at 2.5 eV (16) was observed. These theoretical studies aim to support experimental research on P-2B doping in diamond to achieve p-type conductivity and enhanced optical properties. Full article
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16 pages, 1366 KiB  
Article
Lipid Composition of Nanocarriers Shapes Interactions of Cyclic Antimicrobial Peptide Gramicidin S with Their Membranes
by Volodymyr Berest, Larysa Sichevska, Olga Gorobchenko, Ihor Perepelytsia, Galyna Bozhok and Oleksii Skorokhod
Int. J. Mol. Sci. 2025, 26(14), 6946; https://doi.org/10.3390/ijms26146946 - 19 Jul 2025
Viewed by 475
Abstract
Gramicidin S (GS), an antimicrobial peptide (AMP), exhibits broad-spectrum activity against bacteria and cancer cells but is limited in clinical use due to its cytotoxicity toward eukaryotic cells. Lipid-based delivery systems may overcome this limitation; in this study, we proposed and tested simple [...] Read more.
Gramicidin S (GS), an antimicrobial peptide (AMP), exhibits broad-spectrum activity against bacteria and cancer cells but is limited in clinical use due to its cytotoxicity toward eukaryotic cells. Lipid-based delivery systems may overcome this limitation; in this study, we proposed and tested simple and promising lipid formulations, including dipalmitoylphosphatidylcholine (DPPC), cardiolipin (CL), and cholesterol (CHOL). We evaluated the interactions of these lipid membranes with GS by assessing membrane fluidity, dielectric permittivity, dielectric losses, dielectric relaxation frequency, and static dielectric constant. Among these, membrane fluidity and dielectric permittivity were the most sensitive to GS, showing significant changes in the formulation containing 90 mol% DPPC and 10 mol% CHOL when exposed to 20 μM GS. Notably, although membrane fluidity changed in a dose-dependent manner following GS binding, the liposomes still supported relatively high GS concentrations—up to 80 μM—which is important for future high-dose GS applications. Additionally, we performed preliminary cytotoxicity tests comparing free GS with liposome-carried GS using the tested lipid compositions and observed a significant reduction in GS-associated toxicity on L929 cell line. This study provides new insights into GS–membrane interactions and supports the rational design of AMP nanocarriers for biomedical applications. Full article
(This article belongs to the Collection Feature Papers in Molecular Nanoscience)
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16 pages, 4720 KiB  
Article
Optical Response Tailoring via Morphosynthesis of Ag@Au Nanoparticles
by David Oswaldo Romero-Quitl, Siva Kumar Krishnan, Martha Alicia Palomino-Ovando, Orlando Hernández-Cristobal, José Concepción Torres-Guzmán, Jesús Eduardo Lugo and Miller Toledo-Solano
Nanomaterials 2025, 15(14), 1125; https://doi.org/10.3390/nano15141125 - 19 Jul 2025
Viewed by 330
Abstract
We present a simple method for customizing the optical characteristics of gold-core, silver-shell (Au@Ag) nanoparticles through controlled morphosynthesis via a seed-mediated chemical reduction approach. By systematically adjusting the concentration of cetyltrimethylammonium chloride (CTAC), we obtained precise control over both the thickness of the [...] Read more.
We present a simple method for customizing the optical characteristics of gold-core, silver-shell (Au@Ag) nanoparticles through controlled morphosynthesis via a seed-mediated chemical reduction approach. By systematically adjusting the concentration of cetyltrimethylammonium chloride (CTAC), we obtained precise control over both the thickness of the Ag shell and the particle shape, transitioning from spherical nanoparticles to distinctly defined nanocubes. Bright field and high-angle annular dark-field scanning transmission electron microscopy (BF-STEM and HAADF-STEM), and energy-dispersive X-ray spectroscopy (EDS) were employed to validate the structural and compositional changes. To link morphology with optical behavior, we utilized the Mie and Maxwell–Garnett theoretical models to simulate the dielectric response of the core–shell nanostructures, showing trends that align with experimental UV-visible absorption spectra. This research presents an easy and adjustable method for modifying the plasmonic properties of Ag@Au nanoparticles by varying their shape and shell, offering opportunities for advanced applications in sensing, photonics, and nanophotonics. Full article
(This article belongs to the Section Nanophotonics Materials and Devices)
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13 pages, 9483 KiB  
Article
Abnormal Angle-Dependent Multi-Channel Filtering in Photonic Crystals Containing Hyperbolic Metamaterials
by Mingyan Xie, Yuanda Huang, Haoyuan Qin and Guiqiang Du
Nanomaterials 2025, 15(14), 1122; https://doi.org/10.3390/nano15141122 - 19 Jul 2025
Viewed by 387
Abstract
Tunneling modes in all-dielectric one-dimensional photonic crystals can be utilized for multi-channel filtering. However, these tunneling modes generally blue shift upon increasing the incident angle. When hyperbolic metamaterials are introduced into one-dimensional photonic crystals, the competition between the propagation phase shifts in the [...] Read more.
Tunneling modes in all-dielectric one-dimensional photonic crystals can be utilized for multi-channel filtering. However, these tunneling modes generally blue shift upon increasing the incident angle. When hyperbolic metamaterials are introduced into one-dimensional photonic crystals, the competition between the propagation phase shifts in the dielectric materials and hyperbolic metamaterials can result in different angle dependencies, including blue shift, abnormal zero shift, and abnormal red shift. When the reduction in the propagation phase in the dielectric layer exceeds the increment in the propagation phase in the hyperbolic metamaterial, the tunneling modes are blue-shifted; conversely, when the phase increment in the hyperbolic metamaterial exceeds the phase reduction in the dielectric layer, the tunneling modes are abnormally red-shifted. When the phase changes in the two materials are the same, the tunneling modes are angle independent. In this study, we investigated the multiple filtering effects of one-dimensional photonic structures composed of hyperbolic metamaterials. These composed structures exhibited multiple tunneling modes based on one-, two-, or three-angle dependencies and can be applied in novel optical devices with different angle-dependence requirements. Full article
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15 pages, 4059 KiB  
Article
Surface Fluorination for the Stabilization in Air of Garnet-Type Oxide Solid Electrolyte for Lithium Ion Battery
by Michael Herraiz, Saida Moumen, Kevin Lemoine, Laurent Jouffret, Katia Guérin, Elodie Petit, Nathalie Gaillard, Laure Bertry, Reka Toth, Thierry Le Mercier, Valérie Buissette and Marc Dubois
Batteries 2025, 11(7), 268; https://doi.org/10.3390/batteries11070268 - 16 Jul 2025
Viewed by 283
Abstract
After reviewing the state of the art of the fluorination of inorganic solid electrolytes, an application of gas/solid fluorination is given and how it can be processed. Garnet-type oxide has been chosen. These oxides with an ideal structure of chemical formula A3 [...] Read more.
After reviewing the state of the art of the fluorination of inorganic solid electrolytes, an application of gas/solid fluorination is given and how it can be processed. Garnet-type oxide has been chosen. These oxides with an ideal structure of chemical formula A3B2(XO4)3 are mainly known for their magnetic and dielectric properties. Certain garnets may have a high enough Li+ ionic conductivity to be used as solid electrolyte of lithium ion battery. The surface of LLZO may be changed in contact with the moisture and CO2 present in the atmosphere that results in a change of the conductivity at the interface of the solid. LiOH and/or lithium carbonate are formed at the surface of the garnet particles. In order to allow for handling and storage under normal conditions of this solid electrolyte, surface fluorination was performed using elemental fluorine. When controlled using mild conditions (temperature lower or equal to 200 °C, either in static or dynamic mode), the addition of fluorine atoms to LLZO with Li6,4Al0,2La3Zr2O12 composition is limited to the surface, forming a covering layer of lithium fluoride LiF. The effect of the fluorination was evidenced by IR, Raman, and NMR spectroscopies. If present in the pristine LLZO powder, then the carbonate groups disappear. More interestingly, contrary to the pristine LLZO, the contents of these groups are drastically reduced even after storage in air up to 45 days when the powder is covered with the LiF layer. Surface fluorination could be applied to other solid electrolytes that are air sensitive. Full article
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13 pages, 5917 KiB  
Article
An Experimental 10-Port Microwave System for Brain Stroke Diagnosis—Potentials and Limitations
by Tomas Pokorny, Jan Redr, Hana Laierova, Barbora Smahelova and Jakub Kollar
Sensors 2025, 25(14), 4360; https://doi.org/10.3390/s25144360 - 12 Jul 2025
Viewed by 381
Abstract
Microwave imaging systems show potential as replacements for commonly used stroke diagnostic systems. We developed and tested a 10-port microwave system on a liquid head phantom with ischemic and hemorrhagic strokes of varying sizes and positions. This system allows for visualization of changes [...] Read more.
Microwave imaging systems show potential as replacements for commonly used stroke diagnostic systems. We developed and tested a 10-port microwave system on a liquid head phantom with ischemic and hemorrhagic strokes of varying sizes and positions. This system allows for visualization of changes in dielectric parameters using the TSVD Born approximation, enabling recognition of stroke position and size from the resulting images. The SVM algorithm effectively distinguishes between ischemic and hemorrhagic strokes, achieving 98% accuracy on experimental data, with 99% accuracy in ischemic scenarios and 97% in hemorrhagic scenarios. Using the TSVD Born algorithm, it was possible to precisely image changes in the absolute permittivity of different stroke locations; however, changes in stroke size were more apparent in the variations of absolute permittivity than in the reconstructed stroke size within the antenna plane. Outside this plane, changes in the S-parameters decreased depending on the distance and size of the stroke, making detection and classification more difficult. One ring of antennas around the head proved insufficient, prompting us to focus on developing a system with antennas positioned around the entire head. Full article
(This article belongs to the Special Issue Microwaves for Biomedical Applications and Sensing)
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11 pages, 3334 KiB  
Article
Research on 10 kV Cable Insulation Detection Method Based on Ground Current Phase Variation
by Gang Liu, Yuanming Zhang, Tonghui Ye, Dongdong Zhang, Peigen Cao and Yulan Che
Energies 2025, 18(13), 3586; https://doi.org/10.3390/en18133586 - 7 Jul 2025
Viewed by 327
Abstract
In view of the limitations of traditional offline detection and external excitation online detection of 10 kV cables, this paper proposes a method to evaluate the insulation aging condition of power cables by online measuring of the phase angle of the cable’s ground [...] Read more.
In view of the limitations of traditional offline detection and external excitation online detection of 10 kV cables, this paper proposes a method to evaluate the insulation aging condition of power cables by online measuring of the phase angle of the cable’s ground current, and explores the impact of load fluctuations on cable insulation. By setting the relative permittivity of the cable to characterize the phase variation of the ground current under different aging degrees, and analyzing the phase variation of the cable’s ground current under different load changes at the same aging degree, a load correction-based dynamic dielectric loss evaluation method for cables is proposed. Through the construction of cable simulation models and the processing of field data, the following conclusions have been reached: Under a 1 MW load, the phase angle of the sheath grounding current in the aged phase increases as the dielectric constant of the insulation increases. At the same aging degree, with an increase in load, the phase differences of the aging phase sheath ground current and the steel armor ground current both show a decreasing trend. To eliminate the impact of load, a dynamic dielectric loss load correction method is proposed, and combined with field data analysis, the dynamic dielectric loss of cables under different loads is corrected to a 1 MW load. Specifically: Under 0.3 MW, the correction coefficients k for the sheath and steel armor are 0.609 and 0.778, respectively. Under 3.5 MW, the correction coefficients k for the sheath and steel armor are 1.435 and 1.089, respectively. This study provides a theoretical basis and experimental verification for online cable monitoring methods. Full article
(This article belongs to the Special Issue Trends and Challenges in Power System Stability and Control)
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