Search Results (3,223)

The phytohormone abscisic acid (ABA) plays a central role in organizing adaptive responses in plants to various abiotic stresses, helping the plant minimize the negative impact on growth and development. Rapid and direct detection of ABA is valuable for investigating plant responses to abiotic stress. In this work, we propose a novel label-free, non-competitive immunoassay for detecting and quantifying ABA easily and rapidly using a surface plasmon resonance (SPR) biosensor. The SPR sensor chip was functionalized with a commercial anti-ABA antibody, characterized for its affinity, binding kinetics, and specificity using the same platform. The direct assay demonstrated high specificity and sensitivity, with a calculated limit of detection of 1.36 ng/mL in buffer. The new immunosensor was applied to determine ABA concentrations directly in xylem sap samples from tomato plants subjected to abiotic stress (drought and high salinity) and was able to accurately reflect ABA levels corresponding to the applied stress. The results were comparable to the reference method, ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS), establishing this new immunosensor as a novel detection method for rapid and reliable monitoring of ABA levels associated with abiotic stress in tomato plants. Full article

Switchable microlasers with multicolor output and high spectral purity are of crucial importance for various photonic devices. However, switchable multicolor lasing usually operates in multimode, which largely restricts its practical applications due to the lack of an effective mode selection mechanism. Here, switchable single-mode lasing was successfully achieved in coupled microfiber cavities, in which each microfiber served as both WGM resonator and mode filter for another microfiber. The unique mode selection mechanism is demonstrated experimentally and theoretically in the coupled microfibers. Furthermore, the color of single-mode lasing is tunable at will via the doping of microfibers with different active materials. Our work might provide a platform for building switchable multicolor lasers and gaining further insights into photonic integration. Full article

Salicylic acid (SA) is a key phytohormone that coordinates plant innate immunity and systemic acquired resistance. Because SA levels and signaling are highly dynamic in space and time, a suite of SA-focused tools, including SA-specific microbial biosensors and SA-responsive transcriptional and chemical reporters, has been developed to study them. This review compares three classes of tools in terms of sensitivity, specificity, temporal resolution, invasiveness, quantifiability, and suitability across species. We describe developing genetically encoded sensors that can directly sense salicylic acid and report it, for example, via a fluorescence resonance energy transfer signal or another real-time output. We offer recommendations on method selection by research goal and plant species, as well as combined protocols (long-term autoluminescence plus local probes/biosensors) for cross-validation. Future work should prioritize substrate-free, quantitative SA reporters deployable in crops and the field; coupled with CRISPR-based editing and screening, these tools would enable reporter-guided discovery of immunity genes and rapid engineering of durable disease resistance. Full article

This paper provides an overview of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) methods for analyzing plant materials and herbal formulations, as described in scientific publications from January 2022 to July 2025. It describes the use of TLC in the qualitative and quantitative examination of plant materials and pharmaceutical preparations containing herbs, including profiling plant materials using TLC and applying it to HPTLC plates. It also describes other modern methods that improve component separations, such as applying TLC to profile plant formulations and detect adulterations and contaminants in them. Additionally, it discusses TLC coupled with other methods, such as principal component analysis (PCA), hierarchical cluster analysis (HCA), orthogonal partial least squares discriminant analysis (OPLS-DA), mass spectrometry (MS), nuclear magnetic resonance (NMR), surface-enhanced Raman spectroscopy (SERS), and image analysis (IA). The quantitative determination of biologically active compounds in herbs and herbal formulations is presented based on methods that combine TLC with densitometry. The paper also discusses TLC with effect-oriented analysis, including the detection of antimicrobial, antioxidant, enzyme-inhibiting, endocrine-disrupting, genotoxic, and cytotoxic substances. The advantages, disadvantages, and prospects of analyzing plant material using the TLC technique are indicated. TLC/HPTLC has great prospects for use by regulatory authorities due to the low cost of analysis and high throughput. Full article

Power electronic units (PEUs) in electric drivetrains are subjected to vibration loads that may lead to component fatigue through resonance. This research aims to understand the behavior of passive vibration absorbers and to establish a design approach for them. The proposed systematic design of a nonlinear tuned mass damper (NTMD) for PEUs begins with the separate linear experimental analyses of the PEU and passive absorber. This linear approach is possible due to the Hartman–Grobman theorem. Then the nonlinearity is quantified through frequency sweep measurements. A two-degree-of-freedom (DoF) coupled model is developed for the NTMD, which can be used for analyzing certain parameter changes. To manage the load-dependent responses inherent to nonlinear behavior, design constraints on the attenuated bandwidth and absorber stiffness are introduced, providing clear and optimizable targets. By extending classical linear absorber design principles to nonlinear regimes, the proposed method enhances the durability and reliability of PEU components. Full article

Piezoelectric materials are fundamental elements in modern science and technology due to their unique ability to convert mechanical and electrical energy bidirectionally. They are widely employed in sensors, actuators, and energy-harvesting systems. In this work, we investigate the behavior of commercial lead zirconate titanate (PZT) sensors under frequency-mode excitation using a combined approach of impedance spectroscopy and optical interferometry. The impedance spectra reveal distinct resonance–antiresonance features that strongly depend on geometry, while interferometric measurements capture dynamic strain fields through fringe displacement analysis. The strongest deformation occurs near the first kilohertz resonance, directly correlated with the impedance phase, enabling the extraction of an effective piezoelectric constant (~40 pC/N). Moving beyond the linear regime, laser-induced excitation demonstrates optically driven activation of piezoelectric modes, with a frequency-dependent response and nonlinear scaling with optical power, characteristic of coupled pyroelectric–piezoelectric effects. These findings introduce a frequency-mode approach that combines impedance spectroscopy and optical interferometry to simultaneously probe electrical and mechanical responses in a single setup, enabling non-contact, frequency-selective sensing without surface modification or complex optical alignment. Although focused on macroscale ceramic PZTs, the non-contact measurement and activation strategies presented here offer scalable tools for informing the design and analysis of piezoelectric behavior in micro- and nanoscale systems. Such frequency-resolved, optical-access approaches are particularly valuable in the development of next-generation nanosensors, MEMS/NEMS devices, and optoelectronic interfaces where direct electrical probing is challenging or invasive. Full article

This paper presents a novel asymmetric U-shaped refractive index sensor, which is based on a MIM waveguide and coupled with a U-shaped resonator, which integrates a ring, a circular cavity, and two rectangular cavities (URRCTR), in addition to an inverted rectangular nanostructure. The efficiency of the proposed sensor was investigated and optimized through the FEM. Simulation results indicate that the interaction between the broadband mode supported by the inverted square-shaped structure on the primary waveguide and the confined narrowband mode of the URRCTR resonator generates a distinct asymmetric feature in the transmission profile, a characteristic indicative of Fano resonance. The geometric parameters of the structure are crucial for tuning the Fano resonance features. Through systematic optimization, the sensor achieves a sensitivity of 3480 nm/RIU and a figure of merit (FOM) of 55.23. Due to its high sensitivity, compact footprint, and favorable temperature-dependent properties, the presented sensor reveals considerable promise for various applications in integrated photonic sensing. Full article

Maglev trains represent an advanced form of modern rail transportation. The guideway irregularity presents a common disturbance to the safe and reliable operation of the maglev train. Variations in the air gap between the train and the guideway, induced by the guideway irregularities, exert a significant influence on the train’s dynamic performance, thereby impacting both ride comfort and operational safety. Although previous studies have acknowledged the importance of guideway irregularity, the stochastic effects on the car body vibration across different speeds have not been quantitatively assessed. To fill in this gap, this paper presents a 10-degree-of-freedom maglev train model based on multibody dynamics. The guideway is modelled via the finite element method using Euler–Bernoulli beam theory, and a linearized electromagnetic force equation is employed to couple the guideway and the train dynamics. Furthermore, the measurement data of guideway irregularity from the Shanghai Maglev commercial line are incorporated to evaluate their stochastic effect. Analysis results under varying speeds and irregularity wavelengths identify a resonance speed of 127.34 km/h, attributed to the interplay between guideway periodicity and the train’s natural frequency. When the ratio of the train speed versus irregularity wavelength satisfies the train’s natural frequency, a significant resonance can be observed, leading to an increase in train vibration. Based on the Monte Carlo method, stochastic analysis is conducted using 150 simulations per speed in 200–600 km/h. The maximum vertical acceleration remains relatively stable at 200–400 km/h but increases significantly at higher speeds. When the irregularity is present, greater dispersion is observed with increasing speed, with the standard deviation at 600 km/h reaching 2.7 times that at 200 km/h. Across all tested cases, acceleration values are consistently higher than those without irregularities within the corresponding confidence intervals. Full article

This paper investigates a coupled system of Hadamard fractional p-Laplacian differential equations defined on an unbounded interval, subject to infinitely many points boundary conditions and formulated under a resonance framework. Under suitable growth assumptions imposed on the nonlinear terms of the system, the existence of solutions is established by means of the Ge–Mawhin’s continuation theorem. Moreover, an example is constructed to demonstrate the applicability of the main results. Full article

To mitigate potential interference in a coexisting system, an ultra-wideband (UWB) antenna with triple-band-notched characteristics is proposed. Based on transmission line theory, three notched bands are achieved by utilizing the open- or short-circuited properties of microstrip line resonators and slot resonators. Each antenna element consists of a patch etched with three half-wavelength slots and a one-wavelength strip. Measurement results demonstrate that the antenna exhibits excellent rejection performance at the three designated frequency bands. Furthermore, the effects of array configuration and element deflection angle on mutual coupling are investigated using a 2 × 1 face-to-face multiple-in, multiple-out (MIMO) array. Finally, a two-element MIMO array with high isolation was fabricated and measured. Experimental results show that an isolation level better than 24.6 dB is maintained across the operating band. Full article

To address the engineering challenges of powertrain excitation noise and aggravated low-frequency interior noise caused by armored structures in special-purpose vehicles, this study proposes an in-vehicle acoustic response analysis method based on vibro-acoustic coupling theory. This study presents a method for analyzing in-vehicle acoustic response under engine excitation, integrating Panel Acoustic Contribution Analysis (PACA) with a vibro-acoustic coupling model tailored for armored vehicles. The framework experimentally reveals a condition-independent resonance at 26.5 Hz and reproduces engine-order peaks at 40 Hz, 93.3 Hz, and 140 Hz. Quantitative comparison shows ΔSPL ≤ 2.5 dB and RMSE ≤ 2.2 dB between simulation and experiment, confirming model robustness. Based on these results, conceptual Dynamic Vibration Absorber (DVA) placement guidelines are proposed for dominant panels, providing practical engineering insights for NVH mitigation in armored vehicles. Full article

N-Acetylaspartate (NAA) plays a critical role in neuronal function, metabolism, and neurotransmitter release. Evidence from magnetic resonance spectroscopy indicates diminished NAA levels in individuals diagnosed with schizophrenia and bipolar disorder; however, this process is time-consuming, expensive, and not viable in individuals with acute illness exacerbation. In order to address these limitations, we developed a novel method for the quantification of plasma NAA based on tandem mass spectrometry coupled to liquid chromatography (HPLC-MS). Our study aimed to assess whether plasma NAA levels change during hospitalization and whether these changes correlate with symptomatic improvement in patients experiencing acute psychiatric exacerbations. We recruited 31 inpatients with acute symptoms of psychotic (48.39%) and/or mood (51.61%) disorders. Symptom severity was assessed using the brief psychiatric rating scale, Positive and Negative Syndrome Scale, and Clinical Global Impression Scale. Plasma NAA was measured at admission and discharge. We observed a significant decrease in symptom scores and a significant increase in plasma NAA levels between admission and discharge. The initiation of therapy with lithium salts significantly influenced plasma NAA changes. Our study shows that our HPLC-MS method can detect clinically meaningful changes in plasma NAA levels. These results might lay the groundwork for future research exploring the relationship between plasma NAA levels and cerebral NAA levels measured by MRS. Full article

In order to study the impact on the shock effect when a high-speed train passes over a concrete-filled steel tube (CFST) tied-arch bridge, a dynamic load test was carried out in the background of the Qinjiang River Bridge in Qinzhou, Guangxi Province, to test the bridge displacements, accelerations, and dynamic stresses. The bridge finite element model was coupled with a CRH2 train model developed in SIMPACK to perform ANSYS–SIMPACK co-simulation of vehicle–bridge interactions. Model reliability was verified by comparing simulated results with field measurements under matched operating conditions. On this basis, a parametric study was conducted for single-line operation with a mainline spacing of 4.2–5.4 m (0.4 m increments) and train speeds of 80–270 km/h (10 km/h increments), yielding 80 working conditions to evaluate hanger impact responses. The results indicate that the ANSYS–SIMPACK co-simulation provides reliable predictions. Compared with long hangers, short hangers exhibit larger stress impact coefficients. As train speed increases, the hanger impact effect shows a wavelike increasing trend. When the speed approaches 180–200 km/h, the excitation nears the bridge’s dominant natural frequency, and impact effects on bridge components peak, identifying a critical speed range that is more prone to inducing vehicle–bridge resonance; the impact coefficient of the shock effect on both sides of the train is different: the coefficient on the far side of the bridge is about 2 times of that on the near side of the bridge, so when the impact coefficient is regulated, the unevenness of the impact of the shock effect on both sides can be taken into account. Single-line operation can introduce a lateral load bias on the train, and the distance of the train from the center line is positively correlated with the impact size of the shock effect, with the stress impact coefficient of the shock effect on both sides of the bridge and span deflection increasing as the spacing of the main line increases. Full article

Background/Objectives: We provide a framework for determining how far into the future the spatiotemporal dynamics of tumor growth can be accurately predicted using routinely available magnetic resonance imaging (MRI) data. Our analysis is applied to a coupled set of reaction-diffusion equations describing the spatiotemporal development of tumor cellularity and vascularity, initialized and constrained with diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) MRI data, respectively. Methods: Motivated by experimentally acquired murine glioma data, the rat brain serves as the computational domain within which we seed an in silico tumor. We generate a set of 13 virtual tumors defined by different combinations of model parameters. The first parameter combination was selected as it generated a tumor with a necrotic core during our simulated ten-day experiment. We then tested 12 additional parameter combinations to study a range of high and low tumor cell proliferation and diffusion values. Each tumor is grown for ten days via our model system to establish “ground truth” spatiotemporal tumor dynamics with an infinite signal-to-noise ratio (SNR). We then systematically reduce the quality of the imaging data by decreasing the SNR, downsampling the spatial resolution (SR), and decreasing the sampling frequency, our proxy for reduced temporal resolution (TR). With each decrement in image quality, we assess the accuracy of the calibration and subsequent prediction by comparing it to the corresponding ground truth data using the concordance correlation coefficient (CCC) for both tumor and vasculature volume fractions, as well as the Dice similarity coefficient for tumor volume fraction. Results: All tumor CCC and Dice scores for each of the 13 virtual tumors are >0.9 regardless of the SNR/SR/TR combination. Vasculature CCC scores with any SR/TR combination are >0.9 provided the SNR ≥ 80 for all virtual tumors; for the special case of high-proliferating tumors (i.e., proliferation > 0.0263 day⁻¹), any SR/TR combination yields CCC and Dice scores > 0.9 provided the SNR ≥ 40. Conclusions: Our systematic evaluation demonstrates that reaction-diffusion models can maintain acceptable longitudinal prediction accuracy—especially for tumor predictions—despite limitations in the quality and quantity of experimental data. Full article

In this article, one-dimensional photonic crystal cavities on bending waveguides (PCCoBW) used for achieving high-contrast spectra are proposed, analyzed, and experimentally verified on silicon on insulator (SOI). Both air and dielectric modes of the PCCoBW calculated by the finite-difference time-domain (FDTD) method show finger-ring-like mode profiles with the achievement of high-quality factors (Q∼10⁶), even when the bending radius is less than 50 times the lattice constant. Straight waveguides side-coupled to the cavity are used to access and measure mode resonances. The measured spectra show a high extinction ratio over 40 dB for dielectric modes and 20 dB for air modes, respectively. Both dielectric and air resonant modes are revealed with Q-factors over 3.3 × 10⁴ and 7.9 × 10⁴, respectively, for the coupled PCCoBWs. The proposed PCCoBW could be implemented as high-contrast notch filtering and would benefit a broad range of applications such as optical filters, modulators, sensors, or switches. Full article