Dynamic Response Research Articles

Static and dynamic response of SS316L thin-wall Origami and Auxetic structures fabricated through laser powder bed fusion

Static and dynamic response of SS316L thin-wall Origami and Auxetic structures fabricated through laser powder bed fusion

Insights of cellular and molecular changes in sugarcane response to oxidative signaling

Main conclusionSignificant changes in the proteome highlight essential metabolic adaptations for development and oxidative signaling induced by the treatment of young sugarcane plants with hydrogen peroxide. These adaptations suggest that hydrogen peroxide acts not only as a stressor but primarily as a signaling molecule, triggering specific metabolic pathways that regulate growth and plant resilience.Sugarcane is a crucial crop for sugar and ethanol production, often influenced by environmental signals. Hydrogen peroxide (H2O2) is increasingly recognized as an important signaling molecule that regulates plant development and adaptation. In this study, two-month-old sugarcane plants were treated with varying concentrations of H2O2 to investigate how this molecule acts as a signal at the cellular, biochemical, and proteomic levels. Antioxidant enzyme activity exhibited fluctuations, suggesting a dynamic response to oxidative signaling. Lipid peroxidation, observed through TBARs and scanning electron microscopy, highlighted early membrane modifications. Proteomic analysis (ProteomeXchange PXD048142) identified 2,699 proteins, with 155 showing significant expression changes in response to H2O2 signaling. Bioinformatics, including Principal Component Analysis, revealed distinct proteomic profiles in roots and leaves, indicating tissue-specific metabolic reprogramming. Functional annotation through Gene Ontology and KEGG pathway enrichment showed that oxidative signaling led to the repression of photosynthesis-related pathways in leaves, while promoting pathways related to protein processing, glycolysis, and carbon metabolism in roots. Additionally, bioinformatic tools identified proteins involved in amino acid metabolism, the TCA cycle, and carbohydrate metabolism as critical components of sugarcane's adaptive signaling response. The data suggest that sugarcane plants responded to oxidative signals by adjusting their metabolic networks, promoting sustained development and potential pathways for targeted plant breeding.

Storage Stability and Probiotic Viability of Foxtail Millet Probiotic Powder Enriched with High Protein and Fiber

Aims: The study aimed to evaluate the storage stability of foxtail millet probiotic powder enriched with high protein and dietary fiber under two storage conditions: room temperature (27 ± 1°C) and refrigeration temperature (7 ± 1°C). Study Design: This was an experimental, laboratory-based study. Place and Duration of Study: The study was conducted at the Department of Dairy Microbiology, Dairy Science College, Hebbal, Bengaluru, Karnataka, India, between January 2024 and October 2024. Methodology: Foxtail millet probiotic powder enriched with high protein and dietary fiber was stored in polypropylene sachets under two storage conditions: room temperature and refrigeration temperature. Samples were systematically drawn at 7-day intervals and analyzed for key quality parameters, including probiotic viability, microbial contaminants, water activity, moisture content, alcoholic acidity, and pH. Statistical analyses were performed using Analysis of Variance (ANOVA), with a 5% significance level. A critical difference (CD) value was employed to determine the statistical significance of observed variations between treatments over the storage period. Results: The storage stability of the optimized foxtail millet probiotic dry mix was assessed at both room temperature (27 ± 1°C) and refrigeration (7 ± 1°C) until spoilage or decline in probiotic viability below the threshold value. Probiotic viability declined significantly under both conditions, with a reduction from 11.04 log₁₀ CFU/g to 8.88 log₁₀ CFU/g at room temperature and 8.81 log₁₀ CFU/g under refrigeration. Water activity and moisture content increased over time, reflecting the hygroscopic nature of the mix, while alcoholic acidity rose significantly in both storage conditions. Despite these changes, the mix maintained probiotic viability above the therapeutic threshold (9 log₁₀ CFU/g) for 84 days at room temperature and 105 days under refrigeration, demonstrating its potential as a stable functional food product. Conclusion: The storage study of foxtail millet probiotic powder demonstrated its stability under both refrigeration and ambient conditions, with probiotic viability exceeding the 1 billion CFU/g threshold for up to 105 days and 84 days, respectively. Significant changes in water activity, moisture content, alcoholic acidity, and pH were observed, highlighting the product’s dynamic response to storage conditions.These results support the feasibility of developing shelf-stable, high-protein, high-fiber probiotic millet powders for the health-conscious market.

A Metastable State Facilitates Low Temperature CO Oxidation over Pt Nanoparticles.

The dynamic response of heterogeneous catalytic materials to their environment opens a wide variety of possible surface states which may have increased catalytic activity. In this work, we find that it is possible to generate a surface state with increased catalytic activity over metallic 2nm Pt nanoparticles by performing a thermal treatment of the CO*-covered Pt catalyst. This state is characterised by its ability to oxidise CO to CO2 at room temperature. By combining pressure pulse experiments with in situ spectroscopy we correlate the formation of this high-activity state with the desorption of weakly bound CO* molecules from well-coordinated Pt sites. This high-activity state is metastable, degrading after elevated thermal treatments or upon readsorption of CO at room temperature. We conclude that this metastable state is highly localised to the surface of the nanoparticle, however its exact atomic structure remains open to speculation.

Numerical Modeling and Dynamic and Static Performance Analysis of Hydraulic Mounting

In order to accurately evaluate the dynamic characteristics of the hydraulic bushing, the fluid–structure coupling finite element modeling of the hydraulic bushing was carried out, and its fluid–structure coupling characteristics were analyzed. According to the dynamic characteristic response mechanism of hydraulic bushing, the characteristics of bushing temperature, main spring stiffness, liquid viscosity, inertia channel area, and suspension compensation hole were analyzed. The results show that the main spring stiffness, liquid viscosity, and inertial channel area have significant effects on the performance of the bushing. The basic parameters affecting the installation design are obtained. It provides some theoretical basis and parameter verification for hydraulic bushing design. It provides the basis for the multi-factor design of hydraulic bushing.

Multiscale Nonlinear Response of Extreme Meteorological–Hydrothermal Events in the Upper Reaches of the Yangtze River

ABSTRACTUnder the backdrop of climate warming, the outbreak of short‐term extreme heat events can easily lead to irreversible changes in aquatic ecosystems. Delving into their intrinsic driving mechanisms and nonlinear characteristics is key to preventing natural disasters. This study, focusing on the upper Yangtze River as the research area, constructs a joint copula function model to analyze the joint occurrence probability and return period of extreme meteorological heat events. Through the bivariate cross–wavelet transform method, the study explores the multiscale dynamic response relationships and phase characteristics of extreme meteorological–hydrothermal events in the upper Yangtze River. Furthermore, a joint multifractal model of nonlinear responses for extreme meteorological–hydrothermal events was established. The results indicate that extreme high‐heat meteorological events in the upper Yangtze River tend to occur more frequently and severely, with duration–kurtosis events likely to coincide within a 2‐year return period, as well as high‐intensity low‐frequency high‐heat duration–severity events occurring simultaneously. Overall, before 2005, extreme high‐hydrothermal events exhibited phase characteristics lagging behind meteorological changes, which then shifted from lag to lead. Under three scenarios of change, meteorological–hydrothermal events exhibit a clear nonlinear response relationship. Apart from duration, severity and kurtosis all show significant nonlinear relationships.

Absolute measurement of fast and slow neuronal signals with fluorescence lifetime photometry at high temporal resolution.

The concentrations of extracellular and intracellular signaling molecules, such as dopamine and cAMP, change over both fast and slow timescales and impact downstream pathways in a cell-type specific manner. Fluorescence sensors currently used to monitor such signals in vivo are typically optimized to detect fast, relative changes in concentration of the target molecule. They are less well suited to detect slowly-changing signals and rarely provide absolute measurements of either fast and slow signaling components. Here, we developed a system for fluorescence lifetime photometry at high temporal resolution (FLIPR) that utilizes frequency-domain analog processing to measure the absolute fluorescence lifetime of genetically-encoded sensors at high speed but with long-term stability and picosecond precision in freely moving mice. We applied FLIPR to investigate dopamine signaling in two functionally distinct regions in the striatum, the nucleus accumbens core (NAC) and the tail of striatum (TOS). We observed higher tonic dopamine levels at baseline in the TOS compared to the NAC and detected differential and dynamic responses in phasic and tonic dopamine to appetitive and aversive stimuli. Thus, FLIPR enables simple monitoring of fast and slow time-scale neuronal signaling in absolute units, revealing previously unappreciated spatial and temporal variation even in well-studied signaling systems.

Model-Free Speed Control for Pumping Kite Generator Systems Based on Nonlinear Hyperbolic Tangent Tracking Differentiator

This paper investigates the emerging field of grid-connected wind-powered pumping kite generator system (PKGS), focusing on the challenges associated with the generator/motor speed control. Conventional use of proportional–integral (PI) controllers faces difficulties in meeting requirements for dynamic response, tracking performance, stability, and disturbance rejection encountered in this technology, notably the periodical variation in the rotational speed reference in maximum power point tracking in generation phases and the dynamic response for the step reference in transient ones. To overcome these limitations, a model-free controller (MFC) approach is introduced, also known as intelligent PID controllers. Unlike traditional methods, MFC does not rely on a control model of the system and adapts to uncertainties and disturbances through online estimation based on the system’s input–output behavior. To further improve the control performances, a tracking differentiator based on a nonlinear hyperbolic tangent function is integrated in the MFC. The effectiveness of the proposed strategy is proved through simulations in MATLAB/Simulink. The results highlight the superior performances of the proposed MFC approach in terms of speed control accuracy, response time, and robustness.

Study on the Dynamic Response of the Carbody–Anti-Bending Bars System

Ride comfort is an important requirement that passenger rail vehicles must meet. Carbody–anti-bending system is a relatively new passive method to enhance the ride comfort in passenger rail vehicles with long and light carbody. The resonance frequency of the first bending mode (FBM) of such vehicle is within the most sensitive frequency range that affects ride comfort. Anti-bending bars consist of two bars that are mounted under the longitudinal beams of the carbody chassis using vertical supports. When the carbody bends, the anti-bending bars develop moments in the neutral axis of the carbody opposing the bending of the carbody. In this way, the carbody structure becomes stiffer and the resonance frequency of the FBM can be increased beyond the upper limit of the discomfort range of frequency, improving the ride comfort. The theoretical principle of this method has been demonstrated employing a passenger rail vehicle model that includes the carbody as a free–free Euler–Bernoulli beam and the anti-bending bars as longitudinal springs jointed to the vertical supports. Also, the method feasibility has been verified in the past using an experimental scale demonstrator system. In this paper, a new model of the carbody–anti-bending bar system is proposed by including three-directional elastic elements (vertical and longitudinal direction and rotation in the vertical–longitudinal plane) to model the fastening of the anti-bending bars to the supports and the vertical motion of the anti-bending bars modelled as free–free Euler–Bernoulli beams connected to the elastic elements of the fastening. In the longitudinal direction, the anti-bending bars work as springs connected to the longitudinal elastic elements of the fastening. The modal analysis method is applied to point out the basic properties of the frequency response functions (FRFs) of the carbody–anti-bending bars system, considering the bounce and FBMs of both the carbody and the anti-bending bars. A parametric study of the FRF of the carbody shows that the vertical stiffness of the fastening should be sufficiently high enough to eliminate the influence of the modes of the anti-bending bars upon the carbody response and to reduce the anti-bending bars vibration in the frequency range of interest. Longitudinal stiffness of the elastic elements of the fastening is critical to increase the bending resonance frequency of the carbody out of the sensitive range. Longer anti-bending bars can improve the capability of the anti-bending bars to increase the bending resonance without the risk of interference effects caused by the bounce and bending modes of the anti-bending bars.

Optimum design, nonlinear dynamic response and vibration of graphene-reinforced laminated composite with negative Poisson’s ratio under dynamic load in thermal environment

Optimum design, nonlinear dynamic response and vibration of graphene-reinforced laminated composite with negative Poisson’s ratio under dynamic load in thermal environment

Experimental study of dynamic properties of CMC flat plates in oxidative environment

Accelerated failure of CMC (Ceramic Matrix Composites) structural components in aero engines occurs under oxidative vibrational environments. This study investigates the failure mechanisms of CMCs under high-temperature oxidative vibrational conditions. Experiments were conducted to measure the vibrational response of CMC plates at 1200°C in oxygenated, non-oxygenated, and non-vibrational environments. Combined with techniques such as Energy-Dispersive X-ray Spectroscopy (EDS) and thermogravimetric analysis, the failure mechanisms of CMCs in oxidative vibrational environments were elucidated. The research results indicate that oxidation leads to a decline in the mass and mechanical properties of CMCs, resulting in a reduction in the natural frequency and response amplitude of CMC structures. The presence of vibrational loads causes the opening of matrix cracks, accelerating the oxidation of fibers within the CMC, thereby leading to a more significant decline in CMC plates’ performance and dynamic response.

Tailoring industrial enzymes for thermostability and activity evolution by the machine learning-based iCASE strategy

The pursuit of obtaining enzymes with high activity and stability remains a grail in enzyme evolution due to the stability-activity trade-off. Here, we develop an isothermal compressibility-assisted dynamic squeezing index perturbation engineering (iCASE) strategy to construct hierarchical modular networks for enzymes of varying complexity. Molecular mechanism analysis elucidates that the peak of adaptive evolution is reached through a structural response mechanism among variants. Furthermore, this dynamic response predictive model using structure-based supervised machine learning is established to predict enzyme function and fitness, demonstrating robust performance across different datasets and reliable prediction for epistasis. The universality of the iCASE strategy is validated by four sorts of enzymes with different structures and catalytic types. This machine learning-based iCASE strategy provides guidance for future research on the fitness evolution of enzymes.

Experimental studies of the influence of a gyroscopic damping system on the aeroelastic characteristics of a large aircraft model with elastic pylon-mounted engines under the wing

During production of modern large transport aircraft, engine arrangement mounted on the elastic pylons under the wing is widely used. This arrangement of engines has certain advantages, however, there are also significant dynamic features due to the fact that the partial frequencies of vertical and horizontal (lateral) vibrations of elastic pylon-mounted engines are close to the wing bending and torsional natural frequencies of low modes. It is this frequency spectrum that determines the dynamic response of the aircraft as a whole to external disturbance input, and also significantly affects the dynamic stability of the aircraft. A number of technical solutions have been proposed to damp vibrations of the elastic pylon-mounted engines, including the implementation of the “freed engine” principle. To increase the dissipative parameters of the pylon-mounted engines vibrations, this paper proposes to use special devices – powered gyroscopes, which are the main part of the gyroscopic damping system. Numerous theoretical studies of the possibility of using powered gyroscopes have shown that the stability of a dynamic system can be increased by introducing additional gyroscopic, dissipative and potential forces into it. It is known that a method of direct gyroscopic stabilization is proposed to control aeroelastic oscillations of aircraft structural elements. The article proposes to use powered gyroscopes to damp lightly damped vibrations of pylon-mounted engines of a large aircraft. In order to assess the possibility of practical application of the gyroscopic damping system (GDS), experimental studies were conducted on a dynamically similar flutter model (DSFM) of a large aircraft type An-124 with four pylon-mounted engines under the wing. The studies included two stages: frequency and flutter tests. A gyroscopic device made according to the scheme of a rate gyroscope, which was installed inside the engine nacelle, was used as the GDS. The article presents the results of the experiments to assess the effect of the GDS on the dynamic characteristics of the DPFM. The analysis of the normalized amplitude-frequency characteristics of vertical and horizontal oscillations in the center of mass of the outboard engines shows a significant (by 1.5...5 times) decrease in the peak values of the oscillation amplitudes across the entire frequency range covered. The results of the experimental studies of the effect of the GDS on the flutter characteristics of the aircraft model showed a significant (7...15%) flutter speed enhancement at all levels of aircraft refueling. At the same time, with the gyroscopic damping system powered on, the self-oscillations are sluggish and incoherent, and the flutter modes change from one to another due to the gyroscopic coupling of the longitudinal and lateral motion.

Numerical study on damage behavior of sandwich panels with fiber metal laminates skins subjected to blast and high-velocity fragments impact

The sandwich panel is extensively utilized in various protective structures due to its exceptional load-bearing capacity and blast resistance. In this study, a nonlinear finite element (FE) model is developed to examine the explosive impact behavior of sandwich panels featuring carbon fiber reinforced aluminum laminates (CRALL) skins and aluminum honeycomb core. Utilizing the 3D Hashin criterion and accounting for the strain rate effects on composite plies, the user subroutine, VUMAT, is employed to predict the damage response in composite layers. The Johnson–Cook model and bilinear traction–separation model are used to describe the dynamic responses of the metal layers and the inter-laminar delamination phenomena. The established FE model is validated against existing experimental data in ballistic impact conditions and subsequently employed to predict the explosive impact behavior of the sandwich panel. The dynamic response and damage mechanisms of the sandwich panel under blast impact, fragments impact, and combined impact loading are analyzed. Additionally, the effects of blast mass and impact angle on the explosive impact behavior of the sandwich panel are discussed in detail.

Connection between geometric dimension and dynamic response of bistable composite laminate with variable curvatures

Geometric dimension significantly affects the stable configuration and thereby the nonlinear dynamic response of bistable composite laminate. Previous studies have not focused on the minimum dynamic snap-through excitation of stable configuration transformation. This paper aims to address this gap by taking into account the effect of curvature on the bistable composite laminate with different geometric dimensions. The room-temperature equilibrium stable states of unsymmetric composite plates are obtained by cooling down from the cured temperature with variable curvatures. The governing equations are established by the first-order shear deformation theory, von Karman type nonlinear strain-displacement relation, and Rayleigh-Ritz method. The single- and double-well vibration mechanism are explored by solving the nonlinear equations via fourth-order Runge-Kutta method, and are visualized by bifurcation diagram, phase portrait, time history, Poincare maps and amplitude spectrum. The evolution of the dynamic response under the foundation excitation is estimated, and the effect of geometric dimension on the intra- and inter-well oscillation behaviors are illustrated in detail via theoretical model. Numerical results with finite element method are also obtained qualitatively consistent with the theoretical results. In view of the efficiency of the theoretical model, various geometric dimensions are considered to elucidate the universality of the vibration evolution. The nonlinear phenomenon that emerged in the dynamic response of composite structures provides a conceptual design of energy harvester and adaptive structure.

Balancing the solar irradiance needs: optimising growth in sphagnum palustre through tailored UV-B effects

BackgroundThe carbon sequestration potential and water retention capacity of peatlands are closely linked to the growth dynamics of Sphagnum mosses. However, few studies have focused on the response of Sphagnum moss growth dynamics to UV-B radiation, and existing research has emphasized species differences. In this study, Sphagnum palustre L., a dominant species in the peatlands of Southern China, was selected as a research subject, and its response to UV-B radiation has not been reported before.ResultsIn the field, the morphology and growth differences of Sphagnum palustre under microhabitats with varying UV-B radiation intensities were monitored. Our findings revealed that the height of Sphagnum palustre increased the most in the microhabitats (Juncus community) with the weakest UV-B radiation, however the capitate branch area and biomass of Sphagnum palustre were highest under the Fern community, where UV-B radiation was attenuated by 50% during the summer. In the laboratory, we established four levels of UV-B radiation treatments: 0 MJ/m2/d (control group, no UV-B radiation), 0.2 MJ/m2/d (low UV-B radiation), 0.4 MJ/m2/d (middle UV-B radiation), and 0.8 MJ/m2/d (high UV-B radiation). We investigated the effects of UV-B radiation intensity on the morphology, biomass, and water-holding capacity of Sphagnum palustre after exposing it to UV-B radiation for 30 days. Results indicated that low UV-B radiation (0.2 MJ/m2/d) significantly enhanced the growth of Sphagnum palustre. The capitulum area, plant height, capitulum biomass, and individual biomass of Sphagnum palustre increased by 14.60%, 1.27%, 10.98%, and 16.49%, respectively, compared to the control. Additionally, the maximum water absorption rate of Sphagnum palustre reached 4515.44%. In contrast, under high UV-B radiation (0.8 MJ/m²/d), these indicators significantly decreased, while the water loss rate significantly increased.ConclusionThis study suggests that the intensity of UV-B radiation can be artificially regulated to optimize the growth of Sphagnum, accelerate peatland restoration, and enhance the yield of artificially cultivated Sphagnum moss.

Cell-Type Specific miRNA Regulatory Network Responses to ABA Stress Revealed by Time Series Transcriptional Atlases in Arabidopsis.

In plants, microRNAs (miRNAs) participate in complex gene regulatory networks together with the transcription factors (TFs) in response to biotic and abiotic stresses. To date, analyses of miRNAs-induced transcriptome remodeling are at the whole plant or tissue levels. Here, Arabidopsis's ABA-induced single-cell RNA-seq (scRNA-seq) is performed at different stages of time points-early, middle, and late. Single-cell level primary miRNAs (pri-miRNAs) atlas supported the rapid, dynamic, and cell-type specific miRNA responses under ABA treatment. MiRNAs respond rapidly and prior to target gene expression dynamics, and these rapid response miRNAs are highly cell-type specific, especially in mesophyll and vascular cells. MiRNA-TF-mRNA regulation modules are identified by identifying miRNA-contained feed-forward loops (M-FFLs) in the regulatory network, and regulatory networks with M-FFLs have higher co-expression and clustering coefficient (CC) values than those without M-FFLs, suggesting the hub role of miRNAs in regulatory networks. The cell-type-specific M-FFLs are regulated by these hub miRNAs rather than TFs through sc-RNA-seq network analysis. MiR858a-FBH3-MYB module inhibited the expression of MYB63 and MYB20, which related to the formation of plant secondary wall and the production of lignin, through M-FFL specifically in vascular. These results can provide prominent insights into miRNAs' dynamic and cell-type-specific roles in plant development and stress responses.

Poly(amic acid)-Polyimide Copolymer Interfacial Layers for Self-Powered CH3NH3PbI3 Photovoltaic Photodiodes.

Hybrid organohalide perovskites have received considerable attention due to their exceptional photovoltaic (PV) conversion efficiencies in optoelectronic devices. In this study, we report the development of a highly sensitive, self-powered perovskite-based photovoltaic photodiode (PVPD) fabricated by incorporating a poly(amic acid)-polyimide (PAA-PI) copolymer as an interfacial layer between a methylammonium lead iodide (CH3NH3PbI3, MAPbI3) perovskite light-absorbing layer and a poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT: PSS) hole injection layer. The PAA-PI interfacial layer effectively suppresses carrier recombination at the interfaces, resulting in a high power conversion efficiency (PCE) of 11.8% compared to 10.4% in reference devices without an interfacial layer. Moreover, applying the PAA-PI interfacial layer to the MAPbI3 PVPD significantly improves the photodiode performance, increasing the specific detectivity by 49 times to 7.82 × 1010 Jones compared to the corresponding results of reference devices without an interfacial layer. The PAA-PI-passivated MAPbI3 PVPD also exhibits a wide linear dynamic range of ~103 dB and fast response times, with rise and decay times of 61 and 18 µs, respectively. The improved dynamic response of the PAA-PI-passivated MAPbI3 PVPD enables effective weak-light detection, highlighting the potential of advanced interfacial engineering with PAA-PI interfacial layers in the development of high-performance, self-powered perovskite photovoltaic photodetectors for a wide range of optoelectronic applications.

Numerical Simulation of a Long-Span Steel Truss Bridge Subjected to Blast Loads

Few studies have focused on the blast load effects on steel truss bridges. To address this research gap, this paper conducts an extensive investigation on the above-deck blast loads on a long-span steel truss bridge. The nonlinear dynamic response and damage modes of reinforced concrete (RC) decks and steel members of the bridge under blast loads are numerically studied using the *Load_Blast_Enhanced (LBE) function and Multi-Material Arbitrary Lagrangian-Eulerian (MM-ALE) method in LS-DYNA to identify a cost-efficient approach with reasonable accuracy to simulate a long-span steel truss bridge subjected to blast loads. The LBE method is proved to be more conservative and cost-efficient than the MM-ALE method for simulating blast load effects on the structures. A high-fidelity finite element model of the bridge (i.e., I-35W truss bridge) in LS-DYNA based on the multi-scale modelling technique and the LBE function to simulate blast loads is developed to investigate the structural response under several blast scenarios. The effectiveness of ultra-high-performance concrete (UHPC) in protecting the steel truss members from blast load effects is also been investigated. The results provide valuable insights for bridge owners on the probable response and possible protective measures for long-span steel truss bridges against intensive blast loads.

Dynamic Torsional Response of Pile in Fractional‐Order Viscoelastic Unsaturated Transversely Isotropic Soil With Imperfect Contact

Dynamic Torsional Response of Pile in Fractional‐Order Viscoelastic Unsaturated Transversely Isotropic Soil With Imperfect Contact