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Flexible modelling of time-varying exposures and recurrent events to analyse training load effects in team sports injuries

Abstract We present a flexible modelling approach to analyse time-varying exposures and recurrent events in team sports injuries. The approach is based on the piece-wise exponential additive mixed model where the effects of past exposures (i.e. high-intensity training loads) may accumulate over time and present complex forms of association. In order to identify a relevant time window at which past exposures have an impact on the current risk, we propose a penalty approach. We conduct a simulation study to evaluate the performance of the proposed model, under different true weight functions and different levels of heterogeneity between recurrent events. Finally, we illustrate the approach with a case study application involving an elite male football team participating in the Spanish LaLiga competition. The cohort includes time-loss injuries and external training load variables tracked by Global Positioning System devices, during the seasons 2017–2018 and 2018–2019.

Effect of normal load and strain accumulation on tribological properties of Al3003/St12 multilayered composite produce by severe plastic deformation

Effect of normal load and strain accumulation on tribological properties of Al3003/St12 multilayered composite produce by severe plastic deformation

Categorization of R134a flow-induced vibration and noise in multi-conditions and effect of thermal load on the vibration in automobile air conditioning

The gurgling and hiss noise near thermal expansion valve (TXV) in automobile air conditioning gradually become prominent. However, the causes of noise from the flow-induced vibration (FIV) have not been confirmed. In this paper, the vibration, noise and R134a-flow patterns are recorded synchronously to investigate the FIV causes in multi-conditions. Based on different flow patterns at TXV inlet, all conditions are categorized into four types to explore the relationship of flow patterns, FIV and noise. Then two causes are summarized. Firstly, the intermittent liquid-phase FIV is attributed to the intensive evaporation in a throttling process and mainly occurs in transition from liquid-phase flow to mist flow. Secondly, the sustaining two-phase FIV occurs as long as the gas of two-phase flow accelerates through TXV. For liquid-phase FIV, the pressure drop in two-phase region and vapor quality determined by thermal load always show positive correlation with vibration. For two-phase FIV, the annular-wavy flow increases amplitude of vibration peaks, but they are distributed at the similar frequency band regardless of thermal load and flow pattern. The vibration peaks of X, Y and Z are mainly distributed at 6000 Hz–9000 Hz. Decreasing thermal load reduces Y-vibration peak by 83.7 %.

Albumin and Polysorbate-80 Coated Sterile Nanosuspensions of Mebendazole for Glioblastoma Therapy.

The scarcity of existing and novel therapies for brain cancer has significantly affected the survival rate of glioblastoma patients. Mebendazole (MBZ), an antiparasitic agent demonstrated promising activity against brain cancer. However, poor solubility, multiple polymorphs, and insufficient permeability through blood-brain barrier (BBB) restricts its therapeutic efficacy through parenteral administration. The current study aimed to develop, optimize, and characterize sterile, injectable nanosuspension of mebendazole using parenterally acceptable stabilizers. Albumin and polysorbate 80 (PS-80) coated MBZ Nanosuspension (NS) was prepared using wet media milling technique. Design of experiment (DoE) approach was used to understand effect of drug loading versus stabilizer concentration. The optimized MBZ NS showed hydrodynamic diameter of 208.36 ± 0.24 nm with a poly dispersibility index (PDI) of 0.210 ± 0.03 and zeta potential of -20.41 ± 0.36 mV. The IC50 value of MBZ NS in U-87 MG and LN-229 cell lines were found to be 0.49 ± 0.02 μM and 0.48 ± 0.05 μM, respectively. Additionally, MBZ NS demonstrated a 2.65-fold decrease in colony-forming efficiency and a 1.16-fold reduction in migration of the bridging area compared to MBZ. In 3D spheroids of the U-87 MG glioma cell line, MBZ NS exhibited a 50% reduction in tumor growth and increased cell apoptosis compared to the control. MBZ NS formulations were sterilized by gamma irradiation and tested as per the USP sterility test. Albumin-PS 80 coated NS is rendered to be useful parenteral delivery of mebendazole for the treatment of brain cancer.

Asperity interaction induced vibration excitation of cylindrical roller bearings with localized defect

Asperity interaction induced vibration excitation of cylindrical roller bearings with localized defect

Fire Resilience of Load-Bearing Wall Made of Hollow Timber Elements

During a fire load, a charred layer forms on the timber elements, which is a natural protection against fire, so that a certain level of fire resistance could be achieved by using elements with a larger cross-section. However, this modus of fire protection is not always suitable. One of the most commonly used fire protection systems are fire protection boards. In this work, a large-scale fire test was carried out on a protected load-bearing wall made of hollow elements under the effect of sustained mechanical loads and fire exposure. Different stages of charring were observed. The test was aborted at the 91st minute due to a decrease in the load-bearing capacity and integrity criteria. The allowable average temperature rise on the non-exposed side of the specimen (140 K) was not exceeded until the 91st minute of the test, and the allowable maximum temperature rise on the non-exposed side of the specimen (180 K) was not exceeded until the 90th minute of the test. The loss of specimen integrity occurred at the 90th minute of the test. For surfaces protected by fire-resistant panels, it should be considered that the onset of charring is delayed until a certain time. According to EN 1995-1-2, charring can start before the fire protection is removed, but at a lower charring rate than the rates up to the time of failure of the fire protection. The expression proposed in EN 1995-1-2 shows relatively accurate results for certain systems and thicknesses of fire protection linings. However, it does not consider the presence of more than one lining layer or the full range of lining thicknesses themselves. For the wall described in this paper, the predicted failure time of the fire boards would therefore be 41.5 min, which is not consistent with the results of the experiment (51 min). The results of the calculation model according to EN 1995-1-2 did not fully agree with the results of the fire test on the protected load-bearing wall.

Demonstration of a three-active-section DFB laser with photon-photon resonance and detuned loading effects to obtain enhanced bandwidth and maintained high output power

Enhancement of the modulation bandwidth of the directly modulated semiconductor laser has attracted tremendous attention for applications in optical fiber communication and optical interconnects. However, modulation bandwidth is enhanced by some special technology such as integrating the active region or passive region regularly, which lead to low power and complex fabrication. Here we design and demonstrate a monolithic integrated three-active-section distributed feedback (TAS-DFB) laser with enhanced bandwidth theoretically and experimentally. The laser includes three sections: the DFB section, feedback section and active phase section. The three sections share the same multiple quantum-well structure. To enhance the modulation bandwidth beyond the intrinsic modulation bandwidth, both photon-photon resonance (PPR) and detuned loading (DL) effects are utilized to achieve over 55 GHz. The active phase section shows promise in achieving high bandwidth with PPR and relatively high output power of ∼ 10 mW at 25 °C under continuous-wave (CW) operation simultaneously. The fabrication process of the TAS-DFB laser is simplified due to the conventional and identical active layer structure.

Surface characterization of bis-amide calix[4]arene doped SWCNT nanocomposite and its application as an electrochemical sensor for the determination of Al3+ ion

This study focuses on the optical, wettability, morphological and sensing properties of the chromogenic bis-amide calix[4]arene-SWCNT nanocomposite thin film. Nanocomposite solution was done by mixing single-walled carbon nanotubes with 5,17-bis(phenylazo)-26,28 bis{[(ethoxycarbonyl)methylcarbamoyl] methoxy}-25,27-di(ethoxycarbonylmethoxy)-calix[4]arene in chlorobenzene. The possible interactions between bis-amide calixarene and SWCNT that may be responsible for enhancement in certain properties of the nanocomposite were highlighted. Firstly, the surface of the modified electrode was characterized by using UV–visible spectrophotometer and contact angle measurement (CAM). The effect of the SWCNT loading in the solution and the heating process on the film properties plays a crucial role in the optical and wettability properties of the CNTs based films. Then, morphological study was examined before and after CNT incorporation by using scanning electron microscopy. Finally, the sensing properties of bis-amide calix[4]arene-SWCNT thin film coated gold electrode were investigated using electrochemical impedance spectroscopy (EIS) toward the detection of Al3+ ion.

The response characteristics and stability evaluation of vegetated slope under strong wind

As one of the major geological disasters in southeastern China, typhoon-induced vegetation slope instability causes significant loss of life and property each year. Despite the criticality of this issue, the response mechanism of vegetated slopes to wind loading in terms of soil deformation and stability still remains unclear. This research conducted field investigations on 330 historical landslides in Yongjia County, Zhejiang Province, analyzing their spatiotemporal distribution and developmental characteristics to establish a conceptual model. The influence of wind and vegetation conditions on slope dynamic parameters and soil strength parameters were subsequently determined through numerical simulations using FLAC3D software, model tests, and direct shear tests. The results show that: (1) The influence of wind on the dynamic response of vegetated slopes is significantly affected by wind speed. At wind forces ≤ 12 (hurricane: 32.7–36.9 m/s), vegetation plays a positive role in enhancing slope stability. At wind forces ≥ 13 (typhoon: 37.0–41.4 m/s), vegetation exerts a negative influence under the combined action of strong wind loads. (2) Based on the experimentally determined evolution of soil strength parameters, a formula c (v, w) was fitted to express the variation of cohesion with wind speed (v) and moisture content (w). (3) The optimized evaluation model demonstrates increased sensitivity compared to the traditional model, resulting in a 17.88% increase in sliding force and a 10.62–11.64% increase in anti-sliding force. This research accounts for both the direct and indirect effects of wind loading on vegetated slopes. The findings are expected to enhance the stability assessment of vegetated slopes under strong winds and facilitate the development of more accurate machine learning and statistical models in the future.

A slope-based J-integral approach and advanced image processing for assessment of the cyclic fatigue delamination behavior of adhesive joints

A fatigue fracture mechanics methodology was developed and established, employing a slope-based J-integral approach combined with advanced image processing techniques. Adhesively bonded double cantilever beam (DCB) specimens were tested under constant displacement amplitude loading. The beam rotation was tracked by affixing a repetitive pattern on the DCB specimens and capturing images at the maximum displacement amplitude. Using a custom-developed image processing procedure, the beam rotation was deduced. To validate the methodology, DCB fatigue experiments were conducted at 23, 60 and 75 °C on aluminum adherends bonded with a structural 2-K epoxy adhesive. The J-based approach was compared with a conventional, compliance-based linear elastic fracture mechanics (LEFM) method. The epoxy was a rather brittle, high-modulus adhesive with a bond line thickness of 0.25 mm, resulting in predominantly linear elastic material behavior. By analyzing the images taken during fatigue testing, a stiffening effect of the steel load blocks was observed. Excluding pattern elements directly below the load block yielded the best agreement between J-integral and LEFM data. Both approaches were in excellent agreement within the investigated temperature range. The investigated adhesive exhibited a highly temperature-dependent behavior, which was associated with higher crack propagation rates and a lower fatigue threshold at 60 and 75 °C.

Modeling and analysis of internal excitation and vibration characteristics of gears with early-stage crack and 3D tooth surface error

Affected by the tooth surface errors, the vibration characteristics of early crack failures are usually various under different tooth surface precision level. Therefore, to reveal the influence of three-dimensional (3D) tooth surface error (TSE) on the internal excitation and vibration characteristics of gears with early-stage crack (ESC), a coupling internal excitation model of gears with ESC and 3D errors is proposed based on a double-layer iterative method. In this model, the influence of meshing phase between tooth pair and along tooth width direction (TWD) on the time-varying mesh stiffness (TVMS) are simultaneously considered, which overcomes the limitations of traditional models that are only suitable for characterizing the coupled excitation of the two-dimensional tooth profile errors and TVMS. Based on verifying the proposed model, the effects of TSE type, parameters, and load on the TVMS, loaded static transmission error (LSTE), load distributions, and torsional deformation of the cracked gear teeth are investigated, and the vibration characteristics of ESC failures under the effects of 3D TSE are also explored. The research results show that the distribution parameters of 3D TSE have a significant effect on the internal excitation and vibration characteristics of gears with ESC, and thus measuring and evaluating the distribution parameters of TSE can help improve the accuracy of gear fault identification and diagnosis methods.

Numerical investigation on the suction caisson response considering seabed trenches and cyclic loading

As anchors of floating offshore structures, suction caissons endure cyclic loads transmitted by mooring chains. The moving chains repeatedly cut into the seabed, triggering the formation of trench, which further reduces the stability of suction caisson. However, the coupling effects of cyclic loading and trenches on the movement of suction caisson remain unexplored. To address this issue, finite element analyses were conducted to investigate the coupling effect of cyclic loading and trench on the movement of rigid suction in clay, employing a bounding surface constitutive model. The influences of cyclic amplitude, mean load, trench depth and width on the anchor behaviour are analysed. The results show that movement at the fixed loading point on the rigid caisson nonlinearly increases with the amplitude (qam) and mean (qme) of cyclic loading on a trenched seabed. This increase becomes pronounced when qam exceeds 0.15, and qme surpasses 0.35 the caisson's bearing capacity (qref). Additionally, trench dimensions significantly influence the caisson's movement. Specifically, trench depth has complex influence on the caisson's movement pattern, and increasing trench width results in larger movement, especially beyond a certain width. Considering the seabed trenches and cyclic loading, these findings offer valuable insight into the suction caisson movement.

Catalysts screening on production of syngas over novel cobalt-based catalysts supported with dolomite: effect of calcination temperature and Co loading

Catalysts screening on production of syngas over novel cobalt-based catalysts supported with dolomite: effect of calcination temperature and Co loading

Tendon Cell Biology: Effect of Mechanical Loading.

Tendons play a crucial role in the musculoskeletal system, connecting muscles to bones and enabling efficient force transfer. However, they are prone to acute and chronic injuries, which, if not properly repaired, can significantly impair function. Tendinopathy, a prevalent condition affecting approximately 20% of musculoskeletal complaints, arises from an imbalance between micro-injury accumulation and repair processes. The extracellular matrix (ECM) of tendons is a hierarchical structure comprising collagen fibrils, proteoglycans, and glycoproteins that regulate organization, hydration, and mechanical properties. Mechanotransduction pathways, mediated by integrins and focal adhesion complexes, activate signaling cascades such as MAPK/ERK and PI3K/Akt, driving tenocyte gene expression and ECM remodeling. Adaptations to load involve region-specific remodeling, with tensile regions favoring aligned Type I collagen and compressive regions promoting proteoglycans like aggrecan. Stress shielding or reduced loading disrupts these pathways, leading to matrix disorganization and inflammation, predisposing tendons to degenerative changes. Insights into these molecular mechanisms inform rehabilitation strategies to enhance tendon repair and mitigate tendinopathy progression in both athletic and general populations.

Analytical Fragility Surfaces and Global Sensitivity Analysis of Buried Operating Steel Pipeline Under Seismic Loading

The structural integrity of buried pipelines is threatened by the effects of Permanent Ground Deformation (PGD), resulting from seismic-induced landslides and lateral spreading due to liquefaction, requiring accurate analysis of the system performance. Analytical fragility functions allow us to estimate the likelihood of seismic damage along the pipeline, supporting design engineers and network operators in prioritizing resource allocation for mitigative or remedial measures in spatially distributed lifeline systems. To efficiently and accurately evaluate the seismic fragility of a buried operating steel pipeline under longitudinal PGD, this study develops a new analytical model, accounting for the asymmetric pipeline behavior in tension and compression under varying operational loads. This validated model is further implemented within a fragility function calculation framework based on the Monte Carlo Simulation (MCS), allowing us to efficiently assess the probability of the pipeline exceeding the performance limit states, conditioned to the PGD demand. The evaluated fragility surfaces showed that the probability of the pipeline exceeding the performance criteria increases for larger soil displacements and lengths, as well as cover depths, because of the greater mobilized soil reaction counteracting the pipeline deformation. The performed Global Sensitivity Analysis (GSA) highlighted the influence of the PGD and soil–pipeline interaction parameters, as well as the effect of the service loads on structural performance, requiring proper consideration in pipeline system modeling and design. Overall, the proposed analytical fragility function calculation framework provides a useful methodology for effectively assessing the performance of operating pipelines under longitudinal PGD, quantifying the effect of the uncertain parameters impacting system response.

CO2 selectivity and adsorption performance of K2CO3-modified zeolite: a temperature-dependent study.

High-performing zeolite materials for carbon dioxide capture are promising for applications such as flue gas CO2 capture. Potassium carbonate-loaded zeolites can offer a plethora of benefits. In this work, for the first time, zeolite-Y impregnated with K2CO3 was studied as a gas adsorbent (CO2, CH4, and N2) and characterized using TGA (thermogravimetric analyzer), XRD, BET, FTIR, FETEM (Field-Emission Transmission Electron Microscope), and XPS. The effect of carbonate loading, temperature, and pressure was particularly targeted and assessed. Accordingly, for a variation in K2CO3 loading from 5 to 15 wt.%, the CO2 adsorption capacity reduced from 3.61 to 1.73mmolg-1 in the synthesized adsorbents. Among all the cases, KYZC10 exhibited very good cyclic adsorption-desorption performance and thermal stability. Further equilibrium modeling studies indicate that the stable and optimally K2CO3-loaded adsorbent (KYZC10) demonstrates effective adsorption isotherm behavior, making it suitable for different temperature variation processes in commercial carbon dioxide capture applications. The KYZC10 adsorbent's stable performance at varying temperatures contributes to its enhanced economic feasibility. This study also used the ideal adsorbed solution theory (IAST) to predict CO2 selectivity over other gases (CH4 and N2).

Feasibility of successive hydrogen and methane production: Effects of temperature and organic loads on energy potential and microbial dynamics

This study aims to assess the co-digestion of Cassava Wastewater (CW) and glycerol in a two-stage process using fluidized bed reactors (AFBR), verifying the effect of organic loading rate (OLR) and temperature (mesophilic [SMR] and thermophilic [STR]) in sequential reactors on CH4 production. The OLR ranged from 1.2 to 15 g COD.L−1.d−1 and the hydraulic retention time (HRT) was set at 20 h. The mesophilic sequential reactor (MSR) (average temperature of 30 °C) showed greater tolerance to high OLR and its best MPR was 101.12 mL of CH4.d−1.L−1 h−1, obtained at a OLR of 15 g COD.L−1.d−1). The maximum yield was 341.10 mL of CH4.g−1CODcons, found at the OLR of 1.2 g COD.L−1.d−1. The sequential thermophilic reactor (STR) showed the maximum yield and MPR of 333.03 mL of CH4.g−1CODcons (1.2 g COD.L−1.d−1) and 58.84 mL of CH4.d− 1.L−1 h−1 (12 g COD.L−1.d−1), respectively. Through the massive sequencing analysis of the 16S rRNA gene, it was possible to observe a greater diversity of microorganisms in the TSR than in the MSR. A predominance of acetoclastic microorganisms was observed, with the genera Methanobacterium, Methanosarcina and Methanobrevibacter being the most abundant in both reactors. The two-stage system composed of mesophilic acidogenic reactor + MSR was more suitable for the co-digestion of CW and glycerol than the acidogenic reactor + TSR. These results support the notion of standard operating conditions at the industrial plant, where the cassava processing process is carried out at room temperature (25–30 °C).

Production of aromatic hydrocarbons from catalytic fast pyrolysis of microalgae over Fe-modified HZSM-5 catalysts.

In this study, catalytic fast pyrolysis of the microalga C. pyrenoidosa over Fe-modified HZSM-5 catalysts was performed to produce aromatic hydrocarbons using analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Fe-modified HZSM-5 catalysts were prepared using wet impregnation and characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption and temperature-programmed desorption of ammonia (NH3-TPD) analysis. The effect of Fe loading (3, 5, 8, and 12 wt%) and pyrolysis temperature (450, 500, 550, 600 °C) on the content of pyrolysis products and the content and selectivity of aromatics was examined. Results showed that the parent HZSM-5 catalyst structure remained intact upon increasing Fe loading, although its specific surface area, micropore volume and average pore diameter decreased. In addition, its external specific surface area and total pore volume increased. The modification of Fe metal increased the total acid amount, especially strong acid sites, which were highest when Fe loading was 8 wt%. The prepared Fe-modified HZSM-5 catalysts exhibited pronounced deoxygenation and denitrogenation effects, which significantly decreased the acid, aldehyde, ketone, furan and nitrogenous compounds, thus improving the production of monocyclic aromatic hydrocarbons (MAHs) while effectively suppressing the formation of polycyclic aromatic hydrocarbons (PAHs). The highest content of aromatic hydrocarbons was obtained with an Fe loading of 8 wt% and pyrolysis temperature of 500 °C, which was 42.5%. As Fe loading increased, benzene selectivity decreased, while the selectivity of toluene and xylene first increased and then decreased. With an increase in pyrolysis temperature, benzene selectivity increased, whereas toluene and xylene selectivity increased at first and then decreased. Reaction mechanisms for the formation of aromatic hydrocarbons during the catalytic pyrolysis of microalgae are put forward. This research revealed that catalytic fast pyrolysis of microalgae over Fe-modified HZSM-5 catalysts is an effective method to produce MAHs.

Study on the tensile failure mechanisms of CFRP‐Al flat‐joggle‐flat bonded joints

AbstractThis paper focuses on CFRP‐Al bonded joints, experimentally investigating the effects of joint geometries, different types of adhesives, and overlap lengths on the mechanical properties of bonded joints. Digital Image Correlation (DIC) technology was used to monitor the entire tensile processes, and the deformations and fracture processes of the bonded joints were captured. The strain evolution processes of the joints were obtained through analysis, and quantitative analyses of the joint fracture surfaces were conducted. The results indicate that the special geometric shape of the Flat‐Joggle‐Flat (FJF) bonded joint reduce secondary bending effects. Additionally, the joggle section participates in load transfer, significantly enhancing the joint's mechanical performance and altering its failure mode. Joints using ductile adhesives exhibit higher tensile mechanical properties compared to those using brittle adhesives. Compared to the bearing capacity of single‐lap bonded joints with the same overlap length and adhesive, the mechanical performance improvement of FJF bonded joints using ductile adhesives is less pronounced than that of FJF bonded joints using brittle adhesives. Increasing the overlap length enhances the mechanical properties of bonded joints. This study is expected to provide a reference for the engineering application of FJF bonded joints.Highlights FJF joints have higher bearing capacities compared to single lap joints. Ductile adhesives can effectively increase the bearing capacities of joints. Increasing the overlap length can improve the bearing capacities of joints. The end and middle of the FJF joints jointly bear the load effect. The failure modes of FJF joints are different from that of single lap joints.

Fatigue Failure of Adhesive Joints in Fiber-Reinforced Composite Material Under Step/Variable Amplitude Loading—A Critical Literature Review

Most fatigue-loading research has concentrated on constant-amplitude tests, which seldom represent actual service conditions. Because of the significant time and expense associated with variable-amplitude experiments, researchers often employ block/step-loading tests to evaluate the effects of variable-amplitude loading. These tests utilize various sequences of low-to-high and high-to-low loads to simulate real-world scenarios. Empirical investigations have shown inconsistencies in the damage accumulation under different load sequences. Although literature reviews exist for simulation and experimental methods, there is limited research examining the impact of step/variable-amplitude loading on adhesive joints in composite materials. This review aims to address this gap by comprehensively analyzing the effects of load sequence and block loading on fatigue damage progression in fiber-reinforced polymer composites. Additionally, the applicability of various step-loading fatigue damage accumulation models to adhesive materials is evaluated through numerical simulation to study its suitability in predicting fatigue failure. This review also explores recent theoretical advancements in this field over the past few years, examining more than 100 fatigue damage accumulation models categorized into seven subcategories: (i) linear damage rules, (ii) nonlinear damage curve and two-stage linearization models, (iii) life curve modification models, (iv) models based on crack growth concepts, (v) continuum damage mechanics-based models, (vi) material degradation models, and (vii) energy-based models. Finally, numerical simulations using the most common nonlinear cumulative fatigue damage accumulation models were conducted to predict fatigue failure in adhesively bonded joints under four step-loading tests, and the results were compared with the experimental data. Numerical simulations revealed the need and scope of further development of a fatigue failure model under step/variable loading. This comprehensive review offers valuable insights into the complex nature of fatigue failure in adhesive joints under variable loading conditions and highlights current state-of-the-art nonlinear fatigue damage accumulation models for adhesive materials.