Search Results (73)

This study presents the successful fabrication of lead zirconate titanate (PZT) thin films on silicon (Si) substrates using a hybrid deposition method combining spin-coating and RF sputtering techniques. Initially, a PZT layer was deposited through four successive spin-coating cycles, followed by an additional layer formed via RF sputtering. The resulting multilayer structure was annealed at ${700 }^{°}$C for 2 h to improve crystallinity. Comprehensive material characterization was conducted using XRD, SEM, cross-sectional SEM, EDX, and UV–VIS absorbance spectroscopy. The analyses confirmed the formation of a well-crystallized perovskite phase, a uniform surface morphology, and an optical band gap of approximately 3.55 eV, supporting its suitability for sensing applications. Building upon these findings, a multilayer PZT-based touch sensor was fabricated and electrically characterized. Low-frequency I–V measurements demonstrated consistent and repeatable polarization behavior under cyclic loading conditions. In addition, $\left|Z\right|$–f measurements were performed to assess the sensor’s dynamic electrical behavior. Although expected dielectric responses were observed, the absence of distinct anti-resonance peaks suggested non-idealities linked to ${\mathrm{Ag}}^{+}$ ion diffusion from the electrode layers. To account for these effects, the classical Butterworth–Van Dyke (BVD) equivalent circuit model was extended with additional inductive and resistive components representing parasitic pathways. This modified model provided excellent agreement with the measured impedance and phase data, offering deeper insight into the interplay between material degradation and electrical performance. Overall, the developed sensor structure exhibits strong potential for use in piezoelectric sensing applications, particularly for tactile and pressure-based interfaces. Full article

Ulcerative colitis is a chronic inflammatory bowel disease characterized by continuous mucosal inflammation of the large bowel. However, by conducting a literature search, it emerges that, although being considered a primary mucosal disorder in a subset of patients, the inflammatory process may extend beyond the mucosal surface. For this reason, we reviewed the pertinent literature to evaluate the evidence related to the aforementioned topic. The literature analysis confirmed that, although ulcerative colitis has to be defined as a primary mucosal disease due to its consistent mucosal onset, it can involve deeper layers of the colonic wall. The inefficacy of anti-inflammatory therapies in a considerable proportion of patients, along with the lack of histologic healing and the persistence of inflammatory status and colonic wall thickening at imaging despite mucosal healing, has led to consider an extension of the disease process beyond the mucosal layer. The recent application of more accurate diagnostic tools, both histological and radiological (i.e., intestinal ultrasound and magnetic resonance), has the potential to underline the early signs of disease extension and progression in order to improve ulcerative colitis clinical management. Full article

Epicardial adipose tissue (EAT), strategically located between the myocardium and the visceral pericardial layer, is increasingly recognized as an active player in cardiovascular health rather than a passive fat depot. EAT secretes a notable array of bioactive molecules known as adipokines, which exert critical exocrine and paracrine effects. Recent research has focused on pericoronary adipose tissue (PCAT)—the EAT surrounding coronary arteries—demonstrating its intricate bidirectional relationship with the vascular wall. Under normal physiological conditions, this interaction promotes vascular homeostasis; however, dysfunctional PCAT can release pro-inflammatory adipokines implicated in the pathogenesis of atherogenesis. Notably, PCAT inflammation has emerged as a significant factor associated with the development of coronary artery disease (CAD) and major cardiovascular events. This review seeks to elucidate the imaging methodologies employed to evaluate EAT, emphasizing cardiac computed tomography (CCT) as the preeminent imaging modality. Unlike echocardiography and cardiac magnetic resonance imaging, CCT not only visualizes and quantifies EAT but also concurrently assesses coronary arteries and PCAT. Recent findings have established the potential of CCT-derived PCAT attenuation as a noninvasive biomarker for coronary inflammation, offering prospects for monitoring therapeutic responses to innovative anti-inflammatory interventions in CAD management. Full article

Background/Objectives: Extracellular vesicles (EVs) are nanoscale, membrane-enclosed structures that play key roles in intercellular communication and biological regulation. Among them, Lactobacillus paracasei-derived EVs (Lp-EVs) have attracted attention for their anti-inflammatory and anti-aging properties, making them promising candidates for therapeutic and cosmetic use. However, methods for specific detection and quantitative evaluation of Lp-EVs are still limited. This study aims to develop a surface plasmon resonance (SPR)-based sensor system for the precise and selective detection of Lp-EVs. Methods: Anti-p40 antibodies were immobilized on gold thin films to construct an SPR sensing platform. The overexpression of the p40 protein on Lp-EVs was confirmed using flow cytometry and Western blotting. For functional evaluation, Lp-EVs were applied to an artificial skin membrane mounted on a Franz diffusion cell, followed by SPR-based quantification and fluorescence imaging to assess their skin penetration behavior. Results: The developed SPR sensor demonstrated high specificity and a detection limit of 0.12 µg/mL, with a linear response range from 0.1 to 0.375 µg/mL. It successfully discriminated Lp-EVs from other bacterial EVs. In the skin diffusion assay, Lp-EVs accumulated predominantly in the epidermal layer without penetrating into the dermis, likely due to their negative surface charge and interaction with the hydrophobic epidermal lipid matrix. Fluorescence imaging confirmed this epidermal confinement, which increased over 24 h. Conclusions: This study presents a sensitive and selective SPR-based platform for detecting Lp-EVs and demonstrates their potential for targeted epidermal delivery. These findings support the use of Lp-EVs in skin-focused therapeutic and cosmetic applications. Future studies will explore strategies such as microneedle-assisted delivery to enhance transdermal penetration and efficacy. Full article

This study innovatively presents a hollow-core anti-resonant fiber integrating double-tube nesting and a single-layer anti-resonant wall. Featuring an exclusive two-layer cladding configuration along with an outer cladding circular ring, it differs significantly from traditional fibers. After careful parameter optimization, at 1.55 μm wavelength, the fiber shows excellent performance. Its confinement loss drops to 0.00088 dB/km, 1–2 orders lower than traditional ones. The proportion between the loss of the lowest higher-order mode and that of the fundamental mode reaches 19,900, indicating excellent single-mode performance. In the case of a bending radius of 11–14.2 cm, the x-polarization loss is below 0.001 dB/km, showing good bending resistance. Through structural comparisons, this paper quantitatively reveals the effects of the anti-resonant wall, cladding tube, and outer cladding ring on fiber performance. From the practical fiber-drawing process, it thoroughly analyzes the impact of the outer connecting tube’s offset angle on fiber performance. This research provides crucial theoretical support for new hollow-core fiber design, manufacture, and application, and is expected to drive technological innovation in this field. Full article

In this study, we present a novel ultra-wideband passive polarization conversion metasurface (PCM) that integrates double V-shaped patterns with circular split-ring resonators. Operating without any external power supply or active components, this design effectively manipulates the polarization state of incident electromagnetic waves. Numerical and experimental results demonstrate that the proposed PCM can convert incident linear polarization into orthogonal states across a wide frequency range of 7.1–22.3 GHz, encompassing the C-, X-, Ku-, and K-bands. A fabricated prototype confirms that the polarization conversion ratio (PCR) exceeds 90% throughout the specified band. Furthermore, we explore an additional application of this passive metasurface for electromagnetic stealth, wherein it achieves over 10 dB of monostatic radar cross-section (RCS) reduction from 7.6 to 21.5 GHz. This broad effectiveness is attributed to strong electromagnetic resonances between the top and bottom layers, as well as the Fabry–Pérot cavity effect, as evidenced by detailed analyses of the underlying physical mechanisms and induced surface currents. These findings confirm the effectiveness of the proposed design and highlight its potential for future technological applications, including 6G communications, radar imaging, anti-interference measures, and electromagnetic stealth. Full article

The energy generated by the impact of vibrations from industrial tools or ongoing activities can be transmitted to humans and cause various injuries. Knitted materials can be considered as parts of anti-vibration equipment as they have proven their ability to absorb shocks. In this study, six spacer knitted fabrics consisting of two outer layers of cotton yarns (Nm 1/50 and Nm 1/40) and cashmere yarns (Nm 2/56) connected by PES monofilaments with a diameter of 0.08 mm were tested. To date, the use of natural yarns in the outer layers of spacer fabrics used in environments subject to vibration has been less studied. The first part of the experiments deals with the measurement of the natural frequencies of the materials, which were determined using the free vibration method. The results show that the direction of the experiment, the yarn count, the stitch density, and the thickness of the material influence the value of the natural frequencies. These values are relevant in order to avoid undesirable resonances that occur when the excitation frequency of an external system overlaps with the natural frequency of the material. In the second part, the vibration transmissibility was simulated using a vibration system with one degree of freedom. The fabrics composed of cotton yarns Nm 1/50 had the highest damping capacity and the highest specific damping coefficient and the lowest value for vibration transmission, which make them recommendable for protective materials. Full article

In this paper, a design of vanadium dioxide for dynamic color gamut modulation based on Fano resonance is proposed. This approach facilitates color modulation by manipulating the phase transition state of vanadium dioxide. The device integrates both broadband and narrowband filters, featuring a structure consisting of a top silver mesh, a layer of vanadium dioxide, and a Fabry–Pérot cavity, which allows for effective modulation of the reflectance spectrum. Simulation results demonstrate that when vanadium dioxide is in its insulating state, the maximum reflectivity observed in the device spectrum, reaching 43.1%, appears at 475 nm. Conversely, when vanadium dioxide transitions to its metallic state, the peak wavelength shifts to 688 nm, accompanied by an increased reflectance peak of 59.3%. Analysis of electric field distributions reveals that the intensity caused by surface plasmonic resonance dominates over the excited Fano resonance while vanadium dioxide is in its insulating state, which is the opposite of when vanadium dioxide transitions to its metallic state. This behavior exhibits an excellent dynamic color-tuning capability. Specifically, the phase transition of vanadium dioxide results in a color difference ∆E₂₀₀₀ of up to 36.7, while maintaining good color saturation. This technique holds significant potential for applications such as dynamic color display and anti-counterfeit labeling. Full article

This paper employs five different general-purpose optimization methods to perform parameter optimization on single-layer hollow antiresonant fibers. It provides guidance on the establishment of hyperparameters for various optimization methods, with the aim of further defining and standardizing the necessary conditions and convergence criteria for applying optimization algorithms to specialty optical fibers. Through numerical experiments, the study ultimately obtains the converged optimal performance and the range of optimized parameter guidance for single-layer, double-layer, and triple-layer antiresonant fibers with different topological structures. Full article

This paper proposes a novel optimization method for hollow-core, anti-resonant fiber based on a gradient descent algorithm assisted via a radial basis-function surrogate model. This approach significantly reduces the number of optimization iterations, achieving a stable improvement in birefringence performance by an order of magnitude across the operating wavelength band. Furthermore, various optimization algorithms were compared, and the indicators of their Pareto sets were analyzed to demonstrate the effectiveness of the proposed method in multi-objective optimization. Full article

Composite nanostructures stabilized by responsive polymers are of undoubted interest for chemical sensors. The combination of a heavy metal core with polymer functionality creates a smart nanobot in which the inertial mass of the nanoparticle enhances the initial adsorption effect of an analyte-sensitive organic nanoactuator. In this report, we discuss advanced QCM sensors in which the informative signal is due to a change in the structural organization, the triggering factor for activation of which is the adsorption of the analyte. Silver nanoparticles of a 60 nm diameter stabilized by a branched polyethyleneimine polymer (BPEI) and low-molecular-weight citric acid (CIT) were used as a sensing coating for SPR and QCM transducers (10 MHz) tested on water and ethyl alcohol vapor. SPR spectroscopy showed the behavior typical of organic sensing layers, whereas the BPEI-coated QCM sensor showed a response of the opposite sign for water and ethanol vapor. The anti-Sauerbrey behavior with an increasing loading of QCM sensors results from changes in the contacts of nanoparticles with the surface and with each other. The dynamic relaxations of the sensor architecture under alternating accelerations, initiated by adsorption on sensitive polymer nanoactuators and enhanced by the presence of “heavy” metal nanoparticles with a high inert mass open the possibility of formulating a fundamentally different approach to the detection of specific analytes than the traditional loading-based approach. Full article

In this work, we propose a new type of hollow-core anti-resonant fiber (HC-ARF) structure called a coin-slot structure. In this type of structure, two more layers of glass walls are added into the outer cladding capillary, which can effectively prevent light from leaking out of the fiber. In aiming to explore the influence of the outer resonant tube on loss at a wavelength of 2 μm, the fundamental mode loss, high-order mode loss, and higher-order mode extinction ratio (HOMER) under different geometric parameters are studied. Full article

The quartz tuning fork (QTF) is a promising instrument for biosensor applications due to its advanced properties such as high sensitivity to physical quantities, cost-effectiveness, frequency stability, and high-quality factor. Nevertheless, the fork’s small size and difficulty in modifying the prongs’ surfaces limit its wide use in experimental research. Our study presents the development of a QTF immunosensor composed of three active layers: biocompatible natural melanin nanoparticles (MNPs), glutaraldehyde (GLU), and anti-IgG layers, for the detection of immunoglobulin G (IgG). Frequency shifts of QTFs after MNP functionalization, GLU activation, and anti-IgG immobilization were measured with an Asensis QTF F-master device. Using QTF immunosensors that had been modified under optimum conditions, the performance of QTF immunosensors for IgG detection was evaluated. Accordingly, a finite element method (FEM)-based model was produced using the COMSOL Multiphysics software program (COMSOL License No. 2102058) to simulate the effect of deposited layers on the QTF resonance frequency. The experimental results, which demonstrated shifts in frequency with each layer during QTF surface functionalization, corroborated the simulation model predictions. A modelling error of 0.05% was observed for the MNP-functionalized QTF biosensor compared to experimental findings. This study validated a simulation model that demonstrates the advantages of a simulation-based approach to optimize QTF biosensors, thereby reducing the need for extensive laboratory work. Full article

A nature-inspired approach was employed through the development of dopamine-modified epoxy coating for anti-icing applications. The strong affinity of dopamine’s catechol groups for hydrogen bonding with water molecules at the ice/coating interface was utilized to induce an aqueous quasi-liquid layer (QLL) on the surface of the icephobic coatings, thereby reducing their ice adhesion strength. Epoxy resin modification was studied by attenuated total reflectance infrared spectroscopy (ATR-FTIR) and nuclear magnetic resonance spectroscopy (NMR). The surface and mechanical properties of the prepared coatings were studied by different characterization techniques. Low-temperature ATR-FTIR was employed to study the presence of QLL on the coating’s surface. Moreover, the freezing delay time and temperature of water droplets on the coatings were evaluated along with push-off and centrifuge ice adhesion strength to evaluate their icephobic properties. The surface of dopamine-modified epoxy coating presented enhanced hydrophilicity and QLL formation, addressed as the main reason for its remarkable icephobicity. The results demonstrated the potential of dopamine-modified epoxy resin as an effective binder for icephobic coatings, offering notable ice nucleation delay time (1316 s) and temperature (−19.7 °C), reduced ice adhesion strength (less than 40 kPa), and an ice adhesion reduction factor of 7.2 compared to the unmodified coating. Full article

We report the design, fabrication, and characterization of hollow-core anti-resonant reflecting optical waveguides (ARROWs) fabricated in a membrane-covered trench. These structures are built on silicon wafers using standard microfabrication techniques, including plasma etching, to form trenches. Four waveguide designs are demonstrated, which have different numbers of thin-film reflecting layers. We demonstrate that optical loss decreases with additional reflecting layers, with measured loss coefficients as low as 1 cm⁻¹. Full article