Dynamic Resistance Research Articles

Superstrong Lightweight Aerogel with Supercontinuous Layer by Surface Reaction.

Breaking the thermal, mechanical and lightweight performance limit of aerogels has pivotal significance on thermal protection, new energy utilization, high-temperature catalysis, structural engineering, and physics, but is severely limited by the serious discrete characteristics between grain boundary and nano-units interfaces. Herein, a thermodynamically driven surface reaction and confined crystallization process is reported to synthesize a centimeter-scale supercontinuous ZrO2 nanolayer on ZrO2-SiO2 fiber aerogel surface, which significantly improved its thermal and mechanical properties with density almost unchanged (≈26 mgcm-3). Systematic structure analysis confirms that the supercontinuous layer achieves a close connection between grains and fibers through Zr─O─Si bonds. The as-prepared aerogel exhibits record-breaking specific strength (≈84615 Nmkg-1, can support up to ≈227272 times aerogel mass) and dynamic impact resistance (withstanding impacts up to 500 times aerogel mass and up to 200 cycling stability at 80% strain). Besides, its temperature resistance has also been greatly optimized (400°C enhancement, stability at 1500°C). This work will provide a new perspective for exploring the limits of lightweight, high strength, and thermal properties of solid materials.

Microstructures and Mechanical Properties of SUS 630 Stainless Steel: Effects of Age Hardening in a Tin Bath and Atmospheric Environments

This study investigates the solution-aging treatment of precipitation-hardening SUS 630 stainless steel, alongside an analysis of the carbon emissions generated by the energy consumed during aging treatments. By employing atmospheric and liquid tin as aging media, the research comprehensively explores the effects of aging treatments on the characteristics of 630 stainless steel. The maximum hardness value for the 630 stainless steel was observed after atmospheric aging at 500 °C for 1 h. The given 630 stainless steel obtained its maximum hardness value after atmospheric aging at 500 °C for 1 h, indicating that the formation of secondary precipitates strengthens the steel’s performance. By leveraging the intrinsic characteristics of liquid tin, using it as an aging medium (Sn bath aging) significantly improves the efficiency of the aging process, achieving mechanical properties comparable to those of atmosphere-aged steel. The 630 stainless steel aged in a Sn bath exhibited a refined martensitic matrix with substantial precipitate formation, contributing to superior impact toughness and dynamic fatigue resistance. With an equivalent mass and performance, Sn bath aging notably reduced the duration of the treatment compared to atmospheric aging, leading to substantial energy savings and reduced carbon emissions. The Sn bath treatment, recognized in metallurgical science and heat treatment for its excellent thermal conductivity and recyclability, shows potential to enhance process efficiency and enable low carbon emissions in the heat treatment industry. By highlighting the differences between aging methods, this study provides solutions for optimizing heat treatment processes and thereby achieving industrial advancement and sustainability goals.

Dynamic Failure Mechanism and Fractal Features of Fractured Rocks Under Quasi-Triaxial Static Pressures and Repeated Impact Loading

Mastering the dynamic mechanical behaviors of pre-stressed fractured rocks under repeated impact loads is crucial for safety management in rock engineering. To achieve this, repeated impact loading experiments were performed on produced fractured samples exposed to varying pre-applied axial and confining pressures using a split Hopkinson pressure bar test system in combination with a nuclear magnetic resonance imaging system, and the dynamic failure mechanism and fractal features were investigated. The results indicate that the dynamic stress–strain curves exemplify typical class II curves, and the strain rebound progressively diminishes with growing impact times. The impact times, axial pressure, and confining pressure all significantly affect the dynamic peak strength, average dynamic strength, dynamic deformation modulus, average dynamic deformation modulus, maximum strain, and impact resistance performance. Moreover, under low confining pressures, numerous shear cracks and tensile cracks develop, which are interconnected and converge to form large-scale macroscopic fracture surfaces. In contrast, specimens under a high confining pressure primarily experience tensile failure, accompanied by localized small-scale shear failure. Under low axial pressure, some shear cracks and tensile cracks emerge, while at high axial pressure, anti-wing cracks and secondary coplanar cracks occur, characterized predominantly by shear failure. In addition, as the confining pressure grows from 8 to 20 MPa, the fractal dimensions are 2.44, 2.32, 2.23, and 2.12, respectively. When the axial pressures are 8, 14, and 20 MPa, the fractal dimensions are 2.44, 2.46, and 2.52, respectively. Overall, the degree of fragmentation of the sample decreases with growing confining pressure and grows with rising axial pressure.

Effect of a novel motion and simultaneous irrigation on the cyclic fatigue resistance of Hyflex EDM OneFile.

The aim of this study was to assess the cyclic fatigue resistance of a single-file system (i.e., Hyflex EDM OneFile), during continuous rotation and reflex dynamic motion with and without irrigation. Cyclic fatigue tests were conducted on 48 new Hyflex EDM One files using two different motions, with and without irrigation. The files were randomly assigned to four groups (n = 12) based on the tested motion and irrigation conditions: continuous rotation and the novel kinematics ReFlex Dynamic motion, with and without irrigation. The dynamic fatigue resistance was measured as the number of cycles to fracture (NCF) in an artificial zirconium canal with a 60° angle and a 5mm radius of curvature at an intracanal temperature. The results were analyzed using the non-parametric Mann-Whitney test, with a significance level established at 5% (p < 0.05). The fractured instruments were examined with a scanning electron microscope. The instruments activated in continuous rotation, irrespective of irrigation conditions, demonstrated significantly higher NCF compared to those in ReFlex Dynamic (p < 0.05). Irrigation significantly impacted the cyclic fatigue resistance of Hyflex EDM in ReFlex Dynamic motion (p < 0.05), while it did not influence the resistance of files tested under continuous rotation (p > 0.05). Within the limitations of this in vitro study, HyFlex EDM One files tested under continuous rotation showed greater resistance to cyclic fatigue compared to those tested with ReFlex Dynamic motion, regardless of irrigation. Continuous hypochlorite irrigation enhanced the cyclic fatigue resistance only of the files tested in ReFlex Dynamic motion.

Synergistic enhancement of the dynamic impact damage resistance and energy absorption of ultra‐high molecular weight polyethylene fiber reinforced composites with multiple plasma modification

AbstractThe study reveals the dynamic impact damage resistance and energy absorption of oxygen/argon/nitrogen multiple plasma modified ultra‐high molecular weight polyethylene (UHMWPE) fiber reinforced composites. The interface bonding properties and impact resistance of the composite were studied by microsphere debonding test, low‐velocity and high‐velocity impact test. The modified parameters are optimized based on quadratic polynomial equation. The impact resistance of the composite was evaluated from the aspects of ballistic limit velocity, failure mode and energy dissipation mechanism. The results showed that compared with untreated composites, the depth of dents and damage area of multiple plasma modified composites were reduced by 43.53% and 11.73%, respectively. The energy absorption and limit velocity of high‐velocity impact were increased by 14.64% and 25.58%, respectively. The modified composites formed an energy dissipation mechanism dominated by fiber breakage. The impact damage resistance and energy absorption of UHMWPE fiber reinforced composites were enhanced with multiple plasma modification.Highlights Multiple plasma modification enhance synergistic energy absorption of composites. The optimum treatment parameters of composites plasma modification were analyzed. Interface bonding properties were evaluated from microscopic perspective.

Genomic insights into the dynamic antibiotic resistance landscape of Vibrio cholerae during the Cholera outbreak 2022 in Odisha, India

This research delves into the evolving dynamics of antibiogram trends, the diversity of antibiotic resistance genes and antibiotic efficacy against Vibrio cholerae strains that triggered the cholera outbreak 2022 in Odisha, India. The study will provide valuable insights managing antimicrobial resistance during cholera outbreaks. Eighty V. cholerae strains isolated during the outbreak were analysed for genotypic variations in associated drug resistance genes using PCR assays. Antibiogram profiles and MIC gradient analysis were performed according CLSI guidelines to assess antibiotic effectiveness. Substitution of amino acid position in the QRDR Region was examined to understand the development of Fluoroquinolone resistance. Elevated resistances in V. cholerae strains were observed against doxycycline, azithromycin, ciprofloxacin, and chloramphenicol. The average MARI registered 0.63 value, exceeding the threshold value 0.2. PCR assays revealed higher prevalence of antibiotic resistance genes, and MIC values observed have surpassed the previously registered values during any cholera outbreaks in India. Novel mutations in the parC gene, specifically Tyr-88→Cys and Ser-85→Leu implicated Fluoroquinolone resistance in V. cholerae. This study urges moving beyond on antibiotic reliance to control cholera, emphasizing alternative strategies like OCV, rehydration therapy, probiotics and Water, Sanitation and Hygiene (WASH) interventions as effective tools to combat cholera outbreaks and mitigate antibiotic resistance.

Flexible Mushroom-Like Cross-Scale Surface with Extreme Pressure Resistance for Telecommunication Lines Anti-Icing/Deicing.

Ice accretion caused by freezing rain or snowstorms is a common phenomenon in cold climates that seriously threatens the safety and reliability of telecommunication lines and other overhead networks. Various anti-icing strategies have been demonstrated through surface engineering to delay ice formation. However, existing anti-icing surfaces still encounter several challenges; for example, surfaces are prone to ice-pinning formation due to the impact of supercooled droplets, which leads to a loss of anti-icing effectiveness. In this study, a mushroom-like cross-scale surface (MCS) with extreme pressure resistance and superior anti-ice-pinning property was reported. Specifically, the designed MCS, featuring multiscale microfeatures, re-entrant structure, heterogeneous sidewalls, and nanoscale particles, exhibits excellent anti-icing properties. Ice formation was determined to occur through a process involving liquid penetration, condensation, icing, and frost filling. By establishing an anti-ice -pinning model and a bubble column model, the relationship between structural characteristics and anti-icing performance was clarified. The MCS demonstrates excellent static liquid repellency (contact angle >167°) and robust dynamic impact resistance (water impact with Weber number ≥300). Furthermore, it exhibits an ultralow ice adhesion strength of 0.46 kPa. Notably, the ice adhesion strength remains below 5 kPa even after 15 deicing cycles. The anti-ice-pinning mechanism and robust icephobicity induced by the micromorphologies of MCS provide valuable insights for effective anti-icing prospects in telecommunication line surfaces and other areas in the field of information and communication technology.

Experimental investigation on dynamic stab resistance of high-performance multi-layer textile materials

Experimental investigation on dynamic stab resistance of high-performance multi-layer textile materials

Recent Advances in Antimicrobial Resistance: Insights from Escherichia coli as a Model Organism.

Antimicrobial resistance (AMR) represents a critical global health threat, and a thorough understanding of resistance mechanisms in Escherichia coli is needed to guide effective treatment interventions. This review explores recent advances for investigating AMR in E. coli, including machine learning for resistance pattern analysis, laboratory evolution to generate resistant mutants, mutant library construction, and genome sequencing for in-depth characterization. Key resistance mechanisms are discussed, including drug inactivation, target modification, altered transport, and metabolic adaptation. Additionally, we highlight strategies to mitigate the spread of AMR, such as dynamic resistance monitoring, innovative therapies like phage therapy and CRISPR-Cas technology, and tighter regulation of antibiotic use in animal production systems. This review provides actionable insights into E. coli resistance mechanisms and identifies promising directions for future antibiotic development and AMR management.

Larger reductions in blood pressure during post-exercise standing, but not middle cerebral artery blood velocity, in resistance-trained versus untrained individuals.

Dynamic resistance exercise (RE) produces sinusoidal fluctuations in blood pressure, with hypotension and cerebral hypoperfusion commonly observed immediately following RE. Whether the cerebral vasculature adapts to these regular blood pressure challenges is unclear. This study examined the cerebrovascular response to post-dynamic RE orthostasis. RE-trained (n=15, female=4) and healthy untrained individuals (n=15, female=12) completed five stands: one after seated rest, with each of the subsequent four stands occurring immediately following a set of 10 repetitions of unilateral leg extension exercise at 60% of their one repetition maximum. Beat-to-beat blood pressure, mean middle cerebral artery blood velocity (MCAvmean) and end-tidal carbon dioxide were measured throughout. During standing the mean arterial blood pressure (MAP) and MCAvmean nadirs were identified. There was no difference between groups for age (mean±SD, 26±7 RE-trained vs. 25±6years untrained, P=0.683) or weight (78±15 vs. 71±15kg, P=0.683). At MAP nadir during the post-exercise stand, a greater reduction in MAP was observed in the RE-trained group (e.g., set 4, -45±11 vs. -36±6mmHg, training effect P=0.026). However, post-exercise stand MCAvmean at MCAvmean nadir was not different (e.g., set 4, -20±7 vs. -17±6cm/s, interaction effect P=0.478). Rate of regulation was higher in the RE-trained group (set 1, 0.301±0.170 vs. 0.167±0.009, training effect P=0.023). Despite RE-trained individuals demonstrating greater absolute reductions in MAP during orthostasis following RE, there were no differences in MCAvmean, suggesting that habitual RE may mitigate post-exercise cerebral hypoperfusion.

Development of blue-light GaN based micro light-emitting diodes using ion implantation technology

This study fabricated 10 μm chip size μLEDs of blue-light GaN based epilayers structure with different mesa processes using dry etching and ion implantation technology. Two ion sources, As and Ar, were applied to implant into the LED structure to achieve material isolation and avoid defects on the mesa sidewall caused by the plasma process. Excellent turn-on behavior was obtained in both ion-implanted samples, which also exhibited lower leakage current compared to the sample fabricated by the dry etching process. Additionally, lower dynamic resistance (Rd) and series resistance (Rs) were obtained with Ar implantation, leading to a better wall-plug efficiency of 10.66% in this sample. Consequently, outstanding external quantum efficiency (EQE) values were also present in both implant samples, particularly in the sample implanted with Ar ions. This study proves that reducing defects on the mesa sidewall can further enhance device properties by suppressing non-radiative recombination behavior in small chip size devices. Overall, if implantation is used to replace the traditional dry etching process for mesa fabrication, the ideality factor can decrease from 11.89 to 2.2, and EQE can improve from 8.67 to 11.03%.

Isometric Exercise for Blood Pressure and Endothelial Function in Metabolic Syndrome: A Review

Context: Metabolic syndrome (MetS) is characterized by a cluster of metabolic disorders, including hypertension, insulin resistance, and dyslipidemia, which collectively heighten the risk of cardiovascular diseases (CVDs). The global prevalence of MetS is steadily increasing, paralleling the rise in obesity and sedentary lifestyles. Pharmacological treatments for MetS often face challenges such as inadequate blood pressure (BP) control and limited improvements in cardiovascular outcomes. Consequently, there is a growing emphasis on non-pharmacological interventions, particularly exercise. Among various exercise modalities, isometric resistance training (IRT), which involves static muscle contractions without joint movement, has emerged as a promising strategy for effectively lowering BP and enhancing endothelial function, both of which are critical for cardiovascular health. Evidence Acquisition: This comprehensive literature review synthesizes existing research on the effects of isometric exercise on BP regulation and endothelial function in individuals diagnosed with MetS. The review examines studies sourced from databases such as PubMed, Scopus, and Web of Science, focusing on randomized controlled trials, meta-analyses, and observational studies published in peer-reviewed journals. Key discussion areas include the underlying physiological mechanisms of IRT, comparisons with other exercise modalities, clinical implications, and recommendations for future research. Articles were selected based on qualitative and descriptive reviews. Results: Evidence indicates that isometric resistance training effectively reduces both systolic and diastolic BP, achieving results comparable to other exercise forms like aerobic and dynamic resistance training. Furthermore, IRT has significantly improved endothelial function, particularly among populations with MetS. These physiological benefits are attributed to mechanisms such as enhanced nitric oxide bioavailability, reduced oxidative stress, and improved autonomic regulation. Conclusions: The review supports the integration of isometric exercise into hypertension management protocols, especially for individuals with MetS. Isometric resistance training offers a viable non-pharmacological alternative or adjunct to traditional treatments, with the added advantages of accessibility and adaptability for diverse populations. However, further research is necessary to optimize exercise protocols, determine long-term outcomes, and fully elucidate the molecular mechanisms underlying the cardiovascular benefits of IRT.

A new design of predictive plus PID control for second order plus time delay systems

AbstractThis paper proposes two novel predictive proportional‐integral‐derivative (PID) controllers for second‐order non‐self‐balance systems and self‐balance systems with time delays. For second‐order non‐self‐balance systems with time delays, traditional predictive PID controllers suffer from the drawback of failing to return to the setpoint after disturbances. Therefore, this paper introduces a novel double predictive PID controller, termed PPI‐PPD controller, which consists of an inner‐loop predictive PD controller and an outer‐loop predictive PI controller. In second‐order self‐balance systems encountered in practical chemical processes, time delays can lead to longer adjustment times, increased overshoot, and divergence issues. In order to solve these problems, an improved predictive PID (PPID) controller is proposed in this paper, which introduces a compensation link and an anti‐interference link in the traditional predictive PID controller. This enhancement improves the dynamic response and disturbance resistance of the control system. Simulation results demonstrate that both novel predictive PID controllers exhibit excellent control performance and robustness.

Study on the Effect of Variation in Number of Panels on Natural Frequency

This study investigates the effect of varying the number of panels on the natural frequency and mode shape of truss bridges. Using a steel frame bridge as a case study, three different panel configurations (8, 10, and 12 panels) were analyzed through the Damped-DOF System and ABAQUS software. The results show that bridges with fewer panels exhibit lower natural frequencies, while those with more panels have higher frequencies due to increased stiffness. Furthermore, the mode shape analysis indicates that bridges with fewer panels experience greater deformations, potentially impacting their dynamic performance. This research emphasizes the importance of optimizing the number of panels in bridge design to enhance both stiffness and dynamic force resistance. Future research may explore the influence of other structural parameters on natural frequency and mode shape.

Effects of dynamic resistance training on postexercise hypotension and its mechanisms in hypertensive men.

A possible chronic effect of exercise training is the attenuation of the acute decrease in blood pressure (BP) observed after the execution of a session of exercise [i.e. called postexercise hypotension (PEH)]. However, there are few empirical data regarding this issue, and the possible mechanisms involved in this blunted response have not been studied. The study aimed to evaluate the effects of dynamic resistance training (DRT) on PEH and its systemic, vascular, and autonomic mechanisms. Data from 16 middle-aged treated hypertensive men who underwent DRT (eight exercises, 50% of 1RM, three sets until moderate fatigue) three times/week for 10 weeks were analyzed. Before and after the training period, the participants underwent an experimental session in which BP (auscultation), systemic hemodynamics (CO2 rebreathing), vascular function (duplex ultrasound), and cardiovascular autonomic modulation (spectral analysis of heart rate and BP variabilities) were assessed before and after a session of DRT. DRT reduced preexercise systolic BP and mitigated the systolic PEH that occurred before but not after the training period (P = 0.017). DRT did not change the diastolic PEH that occurred with similar magnitude before and after the training period (P = 0.024). DRT did not change the PEH mechanisms, except for cardiac sympathovagal balance that increased significantly more after the session of DRT conducted in the posttraining evaluation (P = 0.017). In medicated hypertensive men, 10 weeks of DRT decreased preexercise systolic BP, abolished systolic PEH, and induced a greater increase in postdynamic resistance exercise sympathovagal balance.

An efficient approach for blood transport in complex interlinked micro-circulatory network

The flow domain of the micro-circulatory network provides additional flow resistance to the blood due to the additional friction forces associated with the fluid interface and the solid–fluid interface. Fahraeus–Lindqvist effect facilitates the blood flow by partitioning it into two layers, plasma and red blood cell, that minimize the flow resistance. In this article, a lumped parameter-based approach is interfaced with the theory of dynamical systems to understand the comprehensive blood flow mechanism in the complex micro-circulatory network in terms of quantified resistance, where the blood obeys non-Newtonian characteristics. The dynamic flow resistance signifies the importance of fluid rheology and its dependence on the network topology. It is observed that hematocrit distribution plays a vital role in flow dynamics and may cause flow instability. The advantage of this model relies on the fact that the equivalent network resistance can act as ubiquitous parameters to understand complex flow dynamics. The results demonstrated that the micro-circulatory network could possibly help to handle the clinical implacability and computational efficiency to further improve the medical diagnostic efficacy.

Synthesis of the influence of some parameters on dynamic shear resistance of coarse soil

Synthesis of the influence of some parameters on dynamic shear resistance of coarse soil

Insight into the effect of Tubificidae on dynamic membrane reactor: Membrane fouling mitigation and Tubificidae-ASM3-dynamic membrane coupled model

To gain insights into the effects of Tubificidae on dynamic membrane sequencing batch reactor (DMSBR), 4 identical DMSBRs were operated with different Tubificidae densities (i.e., 0, 1, 2, 3 g ww/L). Experimental results showed that Tubificidae had a minimal effect on carbon and nitrogen removal but varied effluent turbidity and sludge characteristics. An appropriate density (2 g ww/L) of Tubificidae significantly decreased effluent turbidity and mitigated membrane fouling, which was attributed to the minimized mixed liquor suspended solids (MLSS) and the maximized particle size. A Tubificidae-ASM3-dynamic membrane coupled model was developed by combining the biological model with the dynamic membrane resistance model, incorporating the extracellular polymeric substances (EPS) to characterize its contribution to membrane pore fouling, and introducing an inhibitory function to limit the unrestricted growth of membrane resistance. The model can be considered as a first attempt to describe the observed Tubificidae effects on dynamic membrane reactor.

Effect of dynamic resistance reduction in spiral copper-plated multifilament coated conductors

Abstract Theoretically, it has been shown that the dynamic resistances of coated conductors can be reduced by decreasing their effective width through multifilamentation. In the case of copper-plated multifilament coated conductors, coupling currents are expected to worsen the effect of multifilamentation in reducing dynamic resistance. Therefore, the purpose of this study is to experimentally investigate the dynamic resistances of spiral copper-plated multifilament coated conductors, which are expected to reduce the coupling time constant in a manner similar to twisted low-T c superconducting wires. We measured the dynamic resistance of four different samples—straight monofilament, straight multifilament, spiral monofilament, and spiral multifilament coated conductors—using the four-terminal method. We discuss the dynamic resistivity characteristics of the copper-plated multifilament coated conductors by comparing the magnetic field dependence of the dynamic resistivity, normalized by the critical current of each sample.

Resistance exercise has an antihypertensive effect comparable to that of aerobic exercise in hypertensive patients: a meta-analysis of randomized controlled trials.

Hypertension increases the risk of cerebrovascular disease and death. In addition to aerobic exercise, which is currently recommended for its antihypertensive effects, recent studies have suggested that dynamic and isometric resistance exercises also have antihypertensive effects. However, the magnitude of the antihypertensive effect of such resistance exercises is not well known. To clarify the differences in these effects, we conducted an umbrella review of a meta-analysis of randomized controlled trials (RCTs). A systematic search was performed on the Ovid MEDLINE and Cochrane Library, covering the period from inception to August 1, 2023. Eligible studies were RCTs comparing the effects of exercise and non-exercise on office, home, or ambulatory blood pressure (BP) in hypertensive patients aged 18 years or older. A random effects model meta-analysis was performed to estimate the effect size across multiple studies. A sub-analysis determined outcomes by the type of exercise (aerobic exercise, dynamic resistance exercise, isometric resistance exercise, and combined exercise). Eighty-four RCTs with 5065 hypertensive patients were included in the study. All exercise significantly reduced systolic BP (SBP) and diastolic BP (DBP) compared to non-exercise (SBP:-7.52 mmHg, 95% confidence interval [CI] -8.77 to -6.27, p < 0.001; DBP: -4.36 mmHg, 95% CI - 5.15 to -3.57, p < 0.001). There were no significant differences in the magnitude of the reduction in BP between the types of exercise (p for interaction = 0.815 for SBP, p = 0.417 for DBP). These data from 84 RCTs showed that exercise intervention significantly reduced BP and that resistance exercise has a similar antihypertensive effect to aerobic exercise in hypertensive patients. This meta-analysis showed that exercise significantly reduced blood pressure in hypertensive patients. There were no significant differences in the magnitude of this reduction in BP between the types of exercise.