Search Results (247)

This study re-examines two geologically and geotechnically similar geosynthetic-reinforced soil walls with modular block facings (GRS-MBs) that exhibited markedly different seismic performances during the 1999 Chi-Chi earthquake (M_L = 7.3). Integrating a multi-wedge failure mechanism that captures soil–facing–reinforcement interactions with a nonlinear hyperbolic soil model representing shear stress–displacement behavior along the slip surface, the Force–equilibrium-based Finite Displacement Method (FFDM) provides consistent and robust displacement evaluations over a wide range of input seismic inertial forces. A systematic sensitivity investigation confirms that the FFDM framework responds to parameter variations in a physically meaningful manner, and that displacement predictions remain stable with respect to reasonable uncertainties in soil, reinforcement, and facing properties. The analysis clarifies why two similar GRS-MBs responded so differently during strong shaking and demonstrates the broader applicability of FFDM for displacement-based seismic assessment, including under shaking levels (e.g., k_h ≈ 0.3) that would drive conventional limit–equilibrium calculations to F_s < 1.0, a physically impossible state requiring shear resistance greater than the soil’s ultimate strength. A comparative evaluation of seismic displacement predictions using the Newmark method and FFDM shows that FFDM successfully generates displacement-based seismic resisting curves and reproduces field-observed displacements. In contrast, the Newmark method yields order-of-magnitude variability in predicted movements and may be unsuitable for displacement-sensitive engineered slopes where deformations on the order of several 10⁻³–10⁻² m are practically significant. For interaction-rich GRS-MBs with high values of k_hc, beyond the predictive capability of Newmark’s equation, FFDM offers a practical and physically grounded tool for seismic displacement assessment of reinforced soil structures. Full article

To effectively enhance the seismic performance of traditional Chinese timber structures, this study proposes a reinforcement method utilizing friction dampers. Based on the working mechanism of friction dampers and the extended discrete element theory, an analytical model for timber structures equipped with these dampers was developed and validated through shake table tests. Subsequently, dynamic analyses were conducted to systematically evaluate the enhanced seismic energy dissipation capacity of the ancient timber structures by the reinforcement of friction dampers. The friction coefficient (μ), bolt pre-tension strain (ε), and action distance (l) were selected as key parameters. A multi-objective optimization function was constructed using the weighted sum method, enabling a multi-objective parameter optimization analysis for the friction dampers to identify the optimal parameter combination under specific conditions. The results indicate that the established extended discrete element model effectively simulates the dynamic characteristics of the structure. The installation of friction dampers significantly enhanced the structure’s energy dissipation capacity and substantially reduced the peak displacement. However, due to the initial stiffness introduced by the dampers, the lateral stiffness of the column frame increased markedly, leading to a significant amplification of the acceleration response, with a maximum increase in peak acceleration reaching 77%. The multi-objective optimization analysis revealed that with weighting coefficients λ_a = λ_b = 0.5, the optimal damper parameter combination is μ = 0.36, ε = 102 με, and l = 268 mm. Under these conditions, the structural displacement response decreased by 38.5%, while the acceleration response increased by 93.7%. It is noted that the derived optimal design solutions are pertinent to the specific structural typology and ground motions considered. Full article

Shaking table testing has become a fundamental experimental approach in geotechnical earthquake engineering for investigating seismic soil–structure interaction. Although numerous studies have examined the dynamic behavior of reinforced retaining walls and soil slopes, the existing body of literature remains fragmented, with significant variations in scaling approaches, boundary conditions, input motions, and instrumentation methods. To date, no comprehensive review has critically synthesized these studies to identify consistent behavioral trends and methodological limitations. This paper presents a systematic and critical review of shaking table investigations of geosynthetic-reinforced retaining walls and clayey soil slopes. The review consolidates global experimental findings to evaluate how key parameters—including excitation characteristics, soil density, surcharge loading, reinforcement configuration, and boundary conditions—influence displacement patterns and acceleration amplification. Recurring response mechanisms are identified, such as elevation-dependent amplification, nonlinear frequency effects, and the confinement benefits of reinforcement and surcharge. The review further examines discrepancies among studies and between experimental and numerical results, highlighting challenges related to similitude requirements, boundary effects, and signal fidelity By synthesizing dispersed experimental evidence and critically evaluating methodological variations, this review provides a clearer understanding of seismic response mechanisms and offers guidance for improving experimental consistency and promoting future standardization in shaking table testing. Full article

Animal-assisted interventions (AAIs) are emerging as a promising treatment avenue for adolescent social anxiety. However, the behavioral mechanisms underlying positive results remain unclear. In addition, behavioral signs of discomfort or stress in therapy dogs may suggest concerns about the dog’s welfare. This study examined the associations between stress-linked and affiliative behaviors of adolescents and therapy dogs with adolescent stress reactivity outcomes within an experimental setting in a sample of 50 participants. Linear regression models primarily indicated null findings, with no significant relationships between adolescent affiliative, dog affiliative, or adolescent stress behaviors to self-reported anxiety or psychophysiological arousal. However, the stress-linked behaviors of shake-off and yawning in dogs were negatively associated with adolescent stress reactivity, although the relationships had small effect sizes. These findings provide preliminary insights into the behavioral mechanisms related to changes in adolescent arousal and implications for dog welfare within AAIs. Future research should replicate with larger samples, test for effects with different dogs, and use diverse physiological stress markers for both species involved in the intervention. Additionally, examining the temporal relationships between adolescents and therapy dog behaviors to stress reactivity outcomes would provide insight into causal relationships. Full article

Fusarium circinatum Nirenberg & O’Donnell (the causal agent of Pine Pitch Canker, PPC), one of the most devastating threats to pine forests and nurseries worldwide, induces canker disease on a wide range of pine species. However, its status as a quarantined pathogen and the scarcity of reliable genetic manipulation tools have long impeded in-depth genomic research on this fungus, and the infection mechanisms of F. circinatum remain an urgent area for investigation. A key approach to expounding its pathogenicity is to perform gene editing on candidate genes, which requires an efficient transformation system. Protoplast-mediated transformation is a critical means for investigating plant-pathogen interactions. During the course of this study, we constructed a PEG/CaCl₂-mediated protoplast transformation method for F. circinatum. Following systematic optimization of transformation conditions, strain A015-1 was selected as the model organism. The optimal enzymolysis system consisted of 5 mg/mL Lysing enzymes, 12.5 mg/mL Driselase, and 7.5 mg/mL Snailase, with incubation at 30 °C for 3 h under shaking at 80 rpm. All positive transformants exhibited strong green fluorescent signals. A total of 31 transformants were obtained after hygromycin B (HPH) selection, and PCR verification confirmed successful amplification of the gfp and hph gene fragments in 30 transformants, corresponding to a positive rate of 96%. Transformation efficiency was calculated as the number of PCR-positive transformants per microgram of plasmid DNA, yielding an efficiency of 1 transformant/μg plasmid DNA under optimal conditions. Furthermore, no significant differences were observed in vegetative growth, development, or pathogenicity between the transformants and the wild-type (WT) strain. In addition, Green fluorescent protein (GFP) was efficiently transformed into F. circinatum protoplasts and functionally expressed. Collectively, this study successfully established a stable transformation system for F. circinatum, providing a foundational platform for analyzing virulence-related functional genes involved in host infection and deciphering the molecular mechanisms underlying the pathogen’s colonization of pine hosts. Full article

Background: The extracellular matrix (ECM) plays a central role in the mechanical strength and functional integration of tissue-engineered matrix (TEM), particularly in cardiovascular and load-bearing applications. Mesenchymal stromal cells (MSCs) from different sources may vary in their ECM-forming potential. Methods: In this study, adipose-derived (hADMSC), bone marrow-derived (hBMSC), and umbilical cord-derived MSCs (hUCMSC) were compared with human dermal fibroblasts (HDFBs) as a reference. Cells were seeded onto polyglycolic acid (PGA)/poly-4-hydroxybutyrate (P4HB) scaffolds and cultured for 3 weeks under static or hydrodynamic conditions using orbital shaking. TEM development was assessed macroscopically, histologically (using H&E and Masson’s trichrome stains), and by polarized light microscopy (Picrosirius Red), alongside biochemical assays that quantified DNA, glycosaminoglycan (GAGs), and hydroxyproline (HYP). Results: Hydrodynamically stimulated culture consistently improved ECM deposition across all groups. TEMs exposed to hydrodynamic stimulation (hydrodynamic conditions) were thicker, more uniformly filled, and exhibited increased collagen deposition compared with static TEMs, which remained thinner and showed persistent scaffold remnants. Polarized light analysis demonstrated that dynamic loading promoted collagen maturation in all groups, as evidenced by an increased prevalence of thick, birefringent collagen fibers indicative of mature collagen. Biochemical analyses showed that HDFB-derived TEMs produced the highest total collagen and ECM content under both static and hydrodynamic conditions; however, these matrices remained comparatively thin and densely packed. In contrast, MSC-derived TEMs formed thicker and more spatially distributed ECM in response to hydrodynamic stimulation. Conclusion: Among the MSC sources, hUCDMSC-derived TEMs exhibited the most advanced collagen maturation and the most uniform collagen distribution under hydrodynamically stimulated culture, whereas hADMSC-derived TEMs showed the greatest matrix thickening and volumetric ECM expansion with intermediate collagen maturation. hBMSC-derived TEMs displayed clear responsiveness to hydrodynamic stimulation but remained limited in overall collagen deposition and fiber maturation. These findings underscore that both hydrodynamic stimulation and cell source are critical not only for maximizing ECM deposition, but also for ensuring physiologically relevant collagen maturation and matrix organization in grafts suitable for clinical translation. Full article

To promote the application of wrap-around reinforced soil structures in high-intensity seismic regions, this study systematically investigated the influence of different wrap-around facing types on the seismic performance of reinforced loess slopes. Through shaking table model tests, the dynamic responses of three wrap-around facing types—C-shaped wrap-around facing, secondary-reinforcement wrap-around facing, and self-wrap facing—under the excitation of two seismic waves (El Centro wave and Wenchuan Wolong wave) were compared and analyzed. The test introduced the marginal spectrum energy analysis method to accurately identify the location and evolution process of slope damage. The results indicated that reinforcement significantly enhances the global integrity of the slope, yet the influence of the wrap-around facing type on seismic performance is significant. The C-shaped wrap-around facing exhibited the best global stability and seismic performance, with damage initiating inside the slope body and a good energy dissipation mechanism. The secondary-reinforcement wrap-around facing is prone to stress release and local loosening in the slope crest region due to weak constraints. The self-wrap facing has insufficient restraint at the top, where the reinforcement tends to experience pullout. Compared with the El Centro wave, the Wolong wave, rich in long-period components, induced stronger dynamic responses, resulting in greater slope face displacement, acceleration amplification, marginal spectral amplitude, and reinforcement strain. Significant damage in the slopes initiated in the mid-upper region, and the damage pattern was directly related to the wrap-around facing type. The research findings provide a theoretical basis for the optimal design of reinforced loess slopes in high-intensity seismic zones. Full article

To address the challenge that traditional dam model materials are difficult to simultaneously meet the requirements of microstructural similarity, dynamic damage simulation, and environmental friendliness, a novel microparticle mortar simulated concrete was developed. This new material consists of cement, sand, gypsum, mineral oil, water, and baryte sand. Through systematic material mechanical tests, the effects of each component on the material’s strength, density, and elastic modulus were revealed, and the optimal mix ratio was determined. This enabled precise control of low elastic modulus and had a high density, while the material is environmentally friendly, non-toxic, and compatible with direct contact with natural water. Its mechanical properties are highly similar to those of the prototype concrete. Based on a 1:70 geometric scale, a shaking table model test of the concrete gravity dam-reservoir system was conducted. The dynamic response and damage evolution under empty and full reservoir conditions were compared and analyzed. The study shows that this material can accurately simulate the stress-strain relationship and failure mode of prototype concrete. Under the full reservoir condition, the dam’s fundamental frequency showed only a 2.72% deviation from the numerical simulation, and as the seismic excitation amplitude increased, the changes in the fundamental frequency effectively reflected the accumulation of damage. Under the design seismic motion, the measured accelerations and stress responses for both empty and full reservoir conditions were in good agreement with numerical calculations. Under overload conditions, the acceleration amplification factor at the dam crest decreased with damage accumulation, and the dam neck was identified as the seismic weak zone. As the peak ground acceleration (PGA) increased from 0.15 g to 0.70 g, the fundamental frequency changes effectively reflected the damage accumulation process in the dam, while the hydrodynamic pressure at the dam heel showed a linear increase (457% increase). The experimentally measured hydrodynamic pressure distribution was between the rigid dam and elastic dam hydrodynamic pressures, reflecting the real fluid-structure interaction effect. This study provides a reliable material solution and data support for dam seismic physical model testing. Full article

Transformers are critical components in power systems, and their functionality must be maintained during seismic events. This study conducted multi-directional shaking table tests on a full-scale 154 kV transformer to investigate the seismic response and failure mechanisms of radiator and conservator connections. Measurements of relative displacement, acceleration, and test response spectra (TRS) indicated stable responses of 0.5–1.2 g for the transformer body, whereas the bushings and radiators exhibited amplified accelerations of up to 4 g and 2 g, respectively, along with relative displacements exceeding 20 mm. Under the 500-year return period input motion, leakage was observed at the lower radiator elbow, which is attributed to the combined effects of concentrated relative displacement, acceleration amplification, frequency-dependent energy concentration, and local structural discontinuities. The observed damage patterns were consistent with leakage incidents reported during the 2024 Noto earthquake in Japan. Based on the experimental findings, this study discusses seismic performance enhancement measures for radiator connections and provides experimental evidence to support the seismic safety evaluation of transformers with similar configurations. Full article

Background/Objectives: Virus-like particles (VLPs) are effective vaccine platforms but are susceptible to degradation, which compromises stability and immunogenicity. A key challenge is the lack of sensitive early indicators of instability. This study aimed to systematically evaluate the stability of an aluminum-free recombinant hepatitis E virus VLP vaccine under various stresses and identify predictive markers of instability. Methods: The VLP vaccine was subjected to thermal stress (4 °C, 25 °C, 37 °C, 56 °C for up to 28 d), repeated freeze–thaw cycles (up to 30 cycles), and mechanical agitation (orbital shaking at 100 and 300 rpm for up to 12 d). Stability was assessed using a multi-parameter panel monitoring critical quality attributes: conformational and colloidal stability, formation of high-molecular-weight species, mean particle size, polydispersity index, charge heterogeneity, and antigen content. Results: Changes in charge heterogeneity were the earliest indicator of instability, detectable within 3 days at 25 °C, 8 h at 37 °C, and 4 h at 56 °C, preceding losses in structural integrity or antigen-binding function. The VLPs remained stable at 25 °C for 28 d. Freeze–thaw cycles induced a basic shift in charge variants without compromising structure or function, while high-intensity shaking (300 rpm) caused aggregation after 3–6 d. The effects of common excipients were also characterized. Conclusions: Charge-variant analysis serves as a sensitive and predictive marker for VLP vaccine instability. The study delineates the distinct impacts of different stress factors and provides critical data for optimizing formulation design and storage strategies to enhance VLP vaccine stability. Full article

The vertical actuation of multi-axis seismic simulators usually requires a redundant parallel scheme for high load capacity. Due to geometric over-constraints, the internal force coupling and the nonlinear hysteresis are high; thus, waveform reproduction quality and structural fatigue may result. A displacement–force dual closed loop cooperative control mechanism can address these problems. First, a real-time kinematic model is developed to overcome the platform pose via actuator extension, and second, a dynamic force balance loop is introduced to actively redistribute the load components. In addition, a fuzzy PID controller is incorporated to optimize gain scheduling online, compensating for hydraulic nonlinearities and time-varying structural parameters. In the experiment on a 3 × 3 m 6-DOF shaking table, the presented method performs very favorably compared to traditional methods. Under broadband random excitation, the THD of acceleration waveform drops from 15.2% (single-loop control) to 3.2%, and the internal momentum oscillation amplitude is suppressed by over 70%. The results show that our proposed method eliminates internal force dependence while maintaining high precision trajectory tracking for seismic simulation. Full article

This study systematically characterized the L-cysteine biosynthetic pathway in Bacillus licheniformis and demonstrated that exogenous serine supplementation significantly upregulated the expression of pathway-associated genes, confirming serine as the primary precursor driving L-cysteine synthesis. Through targeted gene deletions, we generated knockout strains BL2ΔglyA, BL2ΔsdaAA, BL2ΔmetC, BL2Δ2, and BL2Δ3 to minimize precursor diversion and product degradation. Combinatorial overexpression of the feedback-resistant mutant cysE^f and the transporter eamA yielded an engineered strain achieving 1.075 g/L L-cysteine in shake-flask fermentation with an 18.69% molar conversion yield. These findings highlight the potential of B. licheniformis as a platform for sulfur metabolic engineering and provide a sustainable fermentation strategy to replace traditional high-pollution hydrolysis-based L-cysteine production. Additionally, this work reveals fundamental differences in sulfur metabolism networks between Gram-positive and Gram-negative bacteria, elucidating microbial metabolic diversity and the cross-regulatory mechanisms linking sulfur, carbon, and nitrogen metabolism. Full article

Rare earth elements are indispensable for a wide range of advanced technologies, which underscores their strategic importance. This study investigates the kinetics of extracting heavy rare earth elements—lutetium, thulium, yttrium, erbium, and dysprosium—from industrial phosphoric acid solutions generated during apatite processing. A comparative approach using both solvent and solid-phase extraction with di-(2-ethylhexyl)phosphoric acid (D2EHPA) was applied to elucidate the underlying mechanisms. Optimal solvent extraction parameters ($V_{aq}:V_{org}$ = 2:1, ${\phi }_{D2EHPA}$ = 0.2, 298 K, stirring at 350 rpm) achieved efficiencies exceeding 85%. Efficient solid-phase recovery was attained under mild conditions (298 K, m:V = 1:10, shaking at 100 opm). The rate-limiting steps were identified as diffusion-controlled for solvent extraction, governed primarily by agitation intensity, and as a mixed external–internal diffusion regime for solid-phase extraction. Calculated activation energies for each element corroborate these findings. Full article

Seismic action significantly affects the mechanical properties and failure characteristics of bridge pile foundations, soft rocks, and sediments. This study, by integrating shaking table tests, numerical simulations, and on-site monitoring, systematically analyzed the influence mechanisms of seismic intensity, sediment characteristics, and pile foundation layout on structural responses. Tests show that the 2.5-layer rock–sand pile exhibits nonlinear bearing degradation under seismic force: when the seismic acceleration increases from 0 to 100 m/s², the bearing capacity of the pile foundation decreases by 55.3%, and the settlement increases from 3.2 mm to 18.5 mm. When the acceleration is ≥2 m/s², the cohesion of the sand layer is destroyed, causing a semi-liquefied state. When it is ≥10 m/s², the resistance loss reaches 80%. The increase in pore water pressure leads to dynamic settlement. When the seismic acceleration is greater than 50 m/s², the shear modulus of the sand layer drops below 15% of its original value. The thickness of the sediment has a nearly linear relationship with the reduction rate of the bearing capacity. When the thickness increases from 0 to 1.4 cm, the reduction rate rises from 0% to 55.3%. When the thickness exceeds 0.8 cm, it enters the “danger zone”, and the bearing capacity decreases nonlinearly with the increase in thickness. The particle size is positively correlated with the reduction rate. The liquefaction risk of fine particles (<0.1 mm) is significantly higher than that of coarse particles (>0.2 mm). The load analysis of the pile cap shows that when the sediment depth is 140 cm, the final bearing capacity is 156,187.2 kN (reduction coefficient 0.898), and the maximum settlement is concentrated at the top point of the pile cap. Under the longitudinal seismic load of the pile group, the settlement growth rate of the piles containing sediment reached 67.16%, triggering the dual effect of “sediment–earthquake”. The lateral load leads to a combined effect of “torsional inclination”, and the stress at the top of the non-sediment pile reaches 6.41MPa. The seismic intensity (PGA) is positively correlated with the safety factor (FS) (FS increases from 1.209 to 37.654 when 10 m/s²→100 m/s²), while sediment thickness (h) is negatively correlated with FS (FS decreases from 2.510 to 1.209 when 0.05 m→0.20 m). The research results reveal the coupled control mechanism of sediment characteristics, seismic parameters, and pile foundation layout on seismic performance, providing key parameters and an optimization basis for bridge design in high-intensity areas. Full article

Waste printed circuit boards (WPCBs) are one of the fastest-growing waste streams and pose a significant environmental challenge while also representing a valuable secondary resource due to their rich metal content, particularly copper (Cu). Since effective recovery of metals requires mechanical pre-treatment and advanced characterization, WPCB boards were subjected to size reduction and then characterized through X-ray fluorescence (XRF), inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM-EDS), and mineral liberation analysis (MLA). Results indicated that copper is predominantly found in coarser particle sizes due to its ductility, while glass fibers and ceramics dominate finer fractions. Liberation studies revealed that Cu is essentially free in fine particles (<100 μm) but tends to remain locked in coarser fractions. Based on these results, gravity separation methods were employed to concentrate the copper: coarse particles (>300 μm) were treated on a shaking table, achieving a Cu recovery of 95%, while fine particles (<300 μm) were processed using a multi-gravity separator (MGS), with recoveries of 94% for 100 × 300 μm and 81.5% for <100 μm size fractions. This study presents a gravity-based separation strategy that combines shaking tables and MGS to optimize Cu recovery from automotive WPCBs. To the authors’ knowledge, the MGS application for WPCBs has received little attention, despite its strong potential for separating this type of waste. The proposed methodology enhances the concentration and purity of the metallic fraction (in this case, Cu), especially in fine particles, which are challenging to work with, while reducing environmental impacts through minimal chemical use, thereby contributing to sustainable e-waste recycling. Full article