Improvement In Strength Research Articles

Sex Differences in Neuromuscular Adaptations Following 12 Weeks of Kettlebell Swing Training.

The purpose of this study was to investigate whether there are sex differences in strength, power, and muscular endurance gains following a 12-week kettlebell swing protocol. Twenty-eight men (29.4 ± 7.3 years; 176.4 ± 6.2 cm; 80.1 ± 11.0 kg; 146.0 ± 22.3 kg in deadlift; 1.8 ± 0.2 kg/body mass deadlift relative strength) and 25 women (32.3 ± 5.5 years; 162.5 ± 7.5 cm; 66.2 ± 9.7 kg; 92.4 ± 17.3 kg in deadlift; 1.4 ± 0.2 kg/body mass deadlift relative strength) participated in this study. Measures of strength in the deadlift, power in the countermovement jump, muscular endurance in the deadlift, and workout of the day (WOD) were obtained before and following six and 12-week time points. Both sexes showed pre- to post-test differences in strength (p < 0.001; one repetition maximum (1RM) improvement of 12.6% for men and 11.7% for women), power (p < 0.001; jump height improvement of 12.9% for men and 6.8% for women), and muscular endurance deadlift test (p < 0.001; improvement in deadlift repetitions of 24.5% for men and 29.2 for women), and only men improved performance in DT WOD (p < 0.001; WOD improvement of 21.3% for men and 1.3% for women). Furthermore, men had greater gains in the power test (p = 0.02) and in the DT WOD endurance test (p = 0.04). Kettlebell training appears to be an effective strategy for increasing strength, power, and endurance in both men and women, but considering the lower responses in power and DT WOD, other strategies should also be considered to optimize women's results in these tests.

Linear polydichlorophosphazene and Ti3C2Tx MXene nanohybrids: Synthesis and application to epoxy resin to improve the fire safety and mechanical properties

Enhancing the fire safety of epoxy resins (EPs) typically requires a significant amount of flame retardants, which often results in considerable degradation of their mechanical properties. To address this issue, a novel flame retardant known as PDCP@DPA@MXene was synthesized and integrated into EP to achieve notable improvements in flame retardancy, smoke suppression, and mechanical strength. By incorporating 1.5 wt% PDCP@DPA@MXene, the impact strength, tensile strength, and elongation at break of the resulting PDM-1.5 %/EP composite reached 12.1 kJ/m2, 57.4 MPa, and 13.0, respectively, reflecting enhancements of 63.5 %, 18.4 %, and 17.1 % compared to the pure EP. The enhancement in tensile strength may be attributed to the high rigidity of Ti3C2Tx MXene, which reinforces the EP matrix. Additionally, the intertwined structure of PDCP@DPA@MXene chains effectively mitigates material fracturing and absorbs impact forces, thus toughening the EP. The presence of phosphorus, nitrogen, and titanate in PDCP@DPA@MXene contributes to the formation of a more compact char layer. The PDM-1.5 %/EP sample achieved a V-0 rating in the vertical UL-94 test and exhibited a high limiting oxygen index of 32.0. Furthermore, the sample containing 2 wt% PDCP@DPA@MXene showed a significant reduction in peak heat release rate (p-HRR) and total heat release (THR), recording values of 689 kW/m2 and 71.9 MJ/m2, which are decreases of 45.1 % and 26.9 %, respectively, compared to pure EP. Additionally, the incorporation of PDCP@DPA@MXene led to a reduction in CO production. These flame-retarded EPs demonstrate strong potential for various applications due to their elevated glass transition temperature and robust thermal stability.

Improvement of strength in single-lap adhesive joints of AlSi10Mg alloys fabricated by laser powder bed fusion

This study deals with the mechanical strength of metallic single-lap joints bonded with adhesive and fabricated by Additive Manufacturing (AM). To this aim, AlSi10Mg alloy has been used to manufacture the specimens using Laser Powder Bed Fusion (LPBF) process. Based on a series of tensile tests on AMed joints, the mechanical strength of the joints was determined. In this paper, a procedure is recommended to improve the strength of AMed single-lap joints. Particularly, a notch is introduced in the adherends, which plays a crucial role in the mechanical strength and failure load of the joints. Therefore, a series of single-lap joints with notch have been printed and examined. Based on the conducted tests, failure load and fracture behavior of the joints with and without notches have been compared. Here, we used the digital image correlation technique to determine strain fields on the surface of the joints. In addition, a series of finite element models has been developed to investigate the stress distributions in the adhesive and simulate the load-carrying behavior of the joints. The obtained results confirm the effective role of notches in adhesive joints for strength improvement of AMed single-lap joints. The outcome of this study can be utilized for fabrication of AMed metallic joints with a higher mechanical strength.

Outcomes of sciatic neurolysis in chronic hamstring tears: a retrospective case series.

Proximal hamstring tears may present with neurological dysfunction due to compression or stretching of the sciatic nerve. The purpose of this study was to evaluate the effectiveness of hamstring repair with concurrent sciatic nerve neurolysis for clinical outcomes and patient symptoms. A retrospective chart review of patients who were diagnosed with hamstring injury at a large tertiary care institution was conducted. Patients with chronic tears (> 6weeks from injury to surgery) who underwent hamstring repair were reviewed for demographics, clinical variables including symptoms of sciatic neuritis, sciatic nerve abnormalities on MRI, and postoperative outcomes. Chi-square tests were used for categorical variables, t test for continuous variables. Pairwise t tests were used to compare average pre- and postoperative strength for patients with and without symptoms of sciatic neuritis. Thirty-two patients with chronic hamstring tears were included in the analysis. Patients were 59.4% female with an average age of 51.4years (SD 13.1). Preoperatively, 27 patients (84.4%) were noted to have symptoms of sciatic neuritis. These patients did not differ in age (p = .677) or sex (p = .374) from patients without preoperative symptoms. Sciatic nerve abnormalities were noted on MRI report in 7 patients who had sciatic nerve symptoms and 0 patients who did not have sciatic nerve symptoms. Symptomatic improvement was seen in 21/26 (81%) of patients who had preoperative neurological symptoms, and in 6/7 (86%) of patients with MRI findings. All patients had equivalent or improved strength postoperatively. A sciatic nerve neurolysis is a safe and effective procedure to perform on patients with preoperative sciatic nerve symptoms and chronic hamstring tears that leads to improvement in neurological symptoms and strength. In neurologically asymptomatic patients with chronic hamstring injuries and MRI findings indicating possible nerve damage, a discussion should be held about the risks and benefits of performing a sciatic nerve neurolysis.

Photobiomodulation as Medicine: Low-Level Laser Therapy (LLLT) for Acute Tissue Injury or Sport Performance Recovery.

Background/Objectives: Low-level laser therapy (LLLT) has gained traction in sports and exercise medicine as a non-invasive therapeutic for preconditioning the body, exertion recovery, repair and injury rehabilitation. LLLT is hypothesized to modulate cellular metabolism, tissue microenvironment(s) and to decrease inflammation while posing few adverse risks. This review critically examines the evidence-base for LLLT effectiveness focusing on immediate care settings and acute/subacute applications (<6 months post-injury). Methods: A comprehensive literature search was conducted, prioritizing systematic reviews, meta-analyses and their primary research papers. Results: Findings are relevant to trainers and athletes as they manage a wide range of issues from superficial abrasions to deeper tissue concerns. LLLT parameters in the research literature include wide ranges. For body surface structures, studies show that LLLT holds promise in accelerating wound healing. In sport performance studies, LLLT is typically delivered pre-exercise and reveals beneficial effects on exertion recovery, improvements in muscle strength, endurance and reduced fatigue. Evidence is less convincing for acute, deep tissue injury models, where most studies do not report significant benefits for functional outcomes over conventional therapeutic modalities. Conclusions: Variability in LLLT delivery parameters and findings across studies underscores a need for clear treatment guidelines for the profession. Technical properties of laser light delivery to the body also differ materially from LED devices. Sport physiotherapists, team physicians, trainers and athletes should understand limitations in the current evidence-base informing photobiomodulation use in high-performance sport settings and weigh potential benefits versus shortcomings of LLLT use in the mentioned therapeutic contexts.

Effect of Silicon Carbide Particulates on Mechanical Behavior of Al5052 Alloy Metal Matrix Composites for Mining Applications

In particular, the impact of Silicon Carbide (SiC) particles on the mechanical properties of stir-cast Al5052 alloy Metal Matrix Composites (MMCs) for rotor blade applications is examined in this work. The goal of integrating SiC particles is to improve mechanical characteristics including wear resistance, tensile strength, and hardness while preserving the ideal weight-tostrength ratio, which is essential for rotor blade performance. The Al5052 matrix was filled with SiC in a variety of compositions (0%, 2%, 4%, 6%, and 8% by weight), and the resultant composites underwent mechanical testing and microstructural examination. Due to the efficient load transfer and reinforcing processes, the results show a considerable improvement in tensile strength and hardness with the addition of SiC particles. Furthermore, microstructural analyses demonstrate a uniform dispersion of SiC in the matrix, which supports the improved performance attributes. Wear resistance of Al5052 alloy is greatly increased when Silicon Carbide (SiC) particles are added as reinforcement. This makes the composite material perfect for applications requiring great durability and longevity to survive hard mining conditions, such as wear plates, conveyor liners, and drill bits in mining machinery components.

Optimizing additive manufacturing parameters for graphene-reinforced PETG impeller production: A fuzzy AHP-TOPSIS approach

Additive manufacturing, particularly 3D printing, has transformed production by enabling precise, layer-by-layer construction with minimal material waste. This study aims to optimize the mechanical properties and production efficiency of impellers manufactured using Graphene-Reinforced Polyethylene Terephthalate Glycol (G-PETG) filament. By employing the Fuzzy Analytic Hierarchy Process (FAHP) and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), we identified optimal 3D printing parameters. The results showed that a 65 % infill density, 0.20 mm layer height, 50 mm/s printing speed, 90 °C platform temperature, 240 °C extruder temperature, and 90 mm/s traverse speed led to a 15 % improvement in tensile strength and a 12 % reduction in production time compared to baseline settings. Additionally, the impellers produced demonstrated superior surface finish and structural integrity, making them suitable for high-performance applications. These findings underscore the importance of parameter optimization in enhancing the performance of 3D-printed components, particularly for applications requiring high mechanical strength and precision.

Investigation of mechanical properties on functionally graded material reinforced with graphene nanoplatelets for biomedical applications

ABSTRACT This research focuses on the mechanical characterization of FG material graded with Graphene nano-platelets (GPLs) in the transverse direction. Different weight percentages of GPL (0–2 wt. %) were incorporated into epoxy resin for manufacturing the FGM using a simple casting method and the effects were analyzed. This paper aims to enhance the material’s performance, especially focusing on its potential use in biomedical tools. Mechanical tests including assessment on tensile, flexural, impact strength, and microhardness demonstrated substantial improvement in strength and stiffness as compared to other nanocomposite structures. Microstructural analysis using scanning electron microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) analysis which hint at the strong chemical interaction and physical association of GPL nanofiller with the epoxy resin. Thermal analysis was conducted using the Dynamic Mechanical Analysis (DMA) test, which revealed enhanced thermal stability of the FG specimen with a higher glass transition temperature than other carbon nanofillers mixed in epoxy resin. This is advantageous for the FG material to maintain its glassy state, maintaining safety and reliability during high-temperature medical applications. All these findings indicate that the proposed FG-GPL material possesses the necessary mechanical properties, suggesting that customized nanofiller integration could lead to significant advancements in medical procedures, such as in vivo stomach biopsy treatments, drug delivery systems, etc. The material also meets specific anatomical requirements and reduces the risk of malfunction, thereby ensuring patient safety as justified by current experimental investigations.

Improvement of strength in low-carbon Nb–Ti weathering steel through Ce microalloying

In this study, a high-strength low carbon Nb–Ti containing weathering steel was developed. The steel achieved a yield strength of 824.4 MPa and an elongation of 24.4% with the addition of 0.030% Ce as a microalloying element. Precipitation strengthening and dislocation strengthening contributed nearly 60% to the yield strength of the steel. The effects of Ce on the dissolution and precipitation behavior of microalloying elements were analyzed through experimental research and first-principles calculations. Additionally, the associated strengthening mechanisms were elucidated. The findings revealed that the Ce–Nb pairs within the 2 to 7 nearest-neighbor configuration in face-centered cubic Fe exhibited a mutual attraction. This attraction promoted the dissolution of microalloyed carbonitrides, leading to a reduction in the volume fraction of precipitates with diameters above 150 nm from 1.3% to 0.62%. Conversely, in the body-centered cubic Fe structure, Ce–Nb atom pairs were mutually repulsive across all configurations. During the coiling process, the addition of Ce increased the formation of nanoprecipitates in the 0.030% Ce–Nb–Ti weathering steel. Particularly, the volume fraction of precipitates with diameters ranging from 20 to 150 nm in the steel increased from 1.6% to 2.7%, while the fraction of nanoprecipitates also increased from 0.051% to 0.31%. The nanoprecipitates formed within the dislocation substructure of the ferrite significantly enhanced steel strength but reduced its plasticity. Additionally, the addition of Ce led to the formation of numerous fine cementite particles in the localized areas of the steel matrix, which contributed up to 49.2 MPa to the overall strength of the steel.

SHED-CM: The Safety and Efficacy of Conditioned Media from Human Exfoliated Deciduous Teeth Stem Cells in Amyotrophic Lateral Sclerosis Treatment: A Retrospective Cohort Analysis.

Amyotrophic lateral sclerosis (ALS) is a progressive and irreversible neurodegenerative disease with limited treatment options. Advances in regenerative medicine have opened up new treatment options. The primary and exploratory objectives of this retrospective cohort study were to evaluate the safety and efficacy of stem cells from human exfoliated deciduous teeth-conditioned media (SHED-CM). Safety assessments included adverse events, vital signs, and laboratory test changes before and after administration, and efficacy was measured using the ALS Functional Rating Scale-Revised (ALSFRS-R), grip strength, and forced vital capacity in 24 patients with ALS treated at a single facility between 1 January 2022, and 30 November 2023. While ALSFRS-R scores typically decline over time, the progression rate in this cohort was slower, suggesting a potential delay in disease progression. Alternatively, improvements in muscle strength and mobility were observed in some patients. Although adverse events were reported in only 3% of cases (no serious allergic reactions), the treatment-induced changes in vital signs and laboratory results were not clinically significant. The SHED-CM treatment is a safe and potentially effective therapeutic option for patients with ALS. Further research is needed to optimize the SHED-CM treatment; however, this study lays the groundwork for future exploration of regenerative therapies for ALS.

A novel test set up to study three-dimensional electrokinetic dewatering of dredged soil

The dredged soil obtained from maintenance activities of water bodies has emerged as a potential alternate fill material for infrastructure development. However, dredged soil requires stabilization due to high initial water content, low shear strength and high compressibility. Among several methods, stabilization of dredged soil by using electrokinetics is one of the effective ground improvement techniques that uses electric field to dewater and strengthen the soil. In this context, a series of experiments were conducted on dredged soil by using a combination of electrokinetic treatment with and without 6 kPa seating pressure (viz., low surcharge). A customized and patented electrokinetic dewatering (EKD) test set up was used for the three-dimensional electrokinetic treatment of soil. The potential difference (in the range of 6 V–48 V) within the soil was achieved by inserting stainless steel pipes of 21.4 mm outer diameter, 1.2 mm thickness, and 170 mm length. Two control tests (with and without seating pressure of 6 kPa) also were performed to understand the effectiveness of EKD. From the study, up to 1057% and 427% increase in dewatering was noted in EKD tests due to application of 24 V (optimum voltage noted in EKD tests) as compared to control tests, without and with seating pressure, respectively. Further, seating pressure with EKD resulted in effective control of crack formation in the dredged soil and uniform improvement in shear strength along the depth (up to 95 kPa). The combination of low surcharge with EKD, adopted in the study, is also expected to yield lower differential settlement, and hence better performance of geotechnical structures built on improved dredged soil. The novel 3-dimensional patented EKD test setup with Arduino-programmed automatic water pumping enables collecting and accurately measuring dewatered effluent volume, performing cone penetration tests on undisturbed soil, and collecting soil samples for determination of water content/physiochemical properties from different locations. Overall, the developed EKD setup can be utilized for evaluating the effectiveness and adopting real-time progress management for EKD or other ground improvement methods, and remediation of sludge, mine tailings, dredged sediments, and contaminated soils.

Comparative study of plasma, laser, and flame induced activation of HDPE liner surfaces of type 4 hydrogen vessels

ABSTRACT In our study, we compare the surface modifications of coarse HDPE surface induced by atmospheric air plasma, CO2 laser, and flame treatments. An order of WCA decrease of air plasma>flame>CO2 laser methods was detected. The improvement in adhesion strength measured 5 days after the activations followed the same trend. FT-IR and EDS proved that different oxygen compounds were formed after treatments, resulting in increased polar component of the total surface energy. Flame activation showed a saturation character regarding the O-moiety. Hydrophobic recovery showed a linear behavior, with a larger decreasing slope for the polar component than the total surface energy. Plasma treatments induced higher recovery rate; however, restore was not complete here either. The effects of the different CO2 irradiation intensities were nonlinear; SEM and roughness measurements revealed surface ablation or structure formation on the different samples, while after plasma and flame treatment a hilly microtexture appeared. With different mechanisms and intensities, all the tested methods are suitable for increasing the adhesion strength on HDPE surfaces.

Effect of Hybrid Nanofillers on the Mechanical Characteristics of Polymethyl Methacrylate Denture Base Composite

The research study focused on enhancing the mechanical characteristics of polymethyl methacrylate (PMMA) denture bases. PMMA is commonly used in dentistry due to its easy fabrication, cost-effectiveness, and favourable physical properties. However, its limitations include low wear resistance, hardness, and mechanical strength, making it less suitable for long-term dental applications. To address these limitations, the study employed a combination of hybrid nano-fillers, specifically HNTs (halloysite nanotubes) and MWCNTs (multi-walled carbon nanotubes), at varying loading levels to improve the mechanical characteristics of the PMMA composite. These nano-fillers underwent treatment by using a coupling agent to enhance their compatibility with PMMA. Key findings of the research include that introducing HNTs/MWCNTs into the PMMA matrix led to a substantial increase in flexural strength, with a significant improvement of 109.1 MPa compared to unfilled PMMA. This indicates that the composite material became more resistant to bending or deformation. There was a substantial rise in flexural modulus values, suggesting improved stiffness in the nanocomposite compared to unfilled PMMA. In addition, the tensile strength of the PMMA composite increased by 64.4 MPa with the addition of the hybrid nano-fillers, indicating enhanced resistance to stretching or pulling forces. The study found that the improvement in flexural and tensile strength was dependent on the concentration of MWCNTs. Increasing the MWCNT concentration up to 0.75 wt.% led to improved mechanical properties, but further increases resulted in a reduction in PMMA properties. Although there was a modest improvement in Vickers hardness (approximately 18.93 kg/mm&amp;lt;sup&amp;gt;2&amp;lt;/sup&amp;gt;), the addition of HNTs/MWCNTs as hybrid nano-fillers effectively enhanced the properties of the PMMA nanocomposite. The study concludes that incorporating hybrid nano-fillers into PMMA could contribute to the longevity and durability of dental composites, addressing some of the material&amp;apos;s inherent limitations. The specific combination and concentration of nano-fillers played a crucial role in determining the mechanical properties of the resulting nanocomposite.

The impact of short-term pelvic floor muscle training on the biomechanical parameters of the pelvic floor among patients with stress urinary incontinence: A pilot study

ObjectiveOur study aimed to improve the understanding of the biomechanical changes occurring in the pelvic floor due to pelvic floor muscle training (PFMT), which is responsible for improving stress urinary incontinence (SUI) symptoms. Study designIn this prospective cohort study, we examined the impact of a six-week PFMT program in women with stress or stress-predominant urinary incontinence on the biomechanical parameters of the pelvic floor. Fifty-two biomechanical parameters were measured by Vaginal Tactile Imager (VTI) at baseline and at a six-week follow-up. In addition, we have assessed the Urinary Distress Inventory (UDI-6), Incontinence Impact Questionnaire (IIQ-7), and Patient’s Global Impression of Severity (PGI-S) scores at enrolment and at six-week follow-up. We have divided our cohort into two groups, Improved Group (IG) and Not-improved Group (NIG), based on the change in UDI-6 score after six weeks and compared the biomechanical changes within and between the two groups. ResultsThe overall cohort included twenty women with stress or stress-predominant SUI based on MESA questionnaire [MESA SUI index (mean ± SD) 63.3 % ± 24.0 %, MESA UUI index (mean ± SD) 13.3 % ± 15.3 %, p < 0.01]. Nine of the 52 VTI parameters have changed significantly after six weeks of PFMT in the entire cohort. Eleven women (IG) achieved the minimum 11-point change in the UDI-6 scaled score. In IG, we found that three VTI parameters differed significantly: Parameter 1: the maximum value of force measured during the VTI probe insertion [(N, mean ± SD) 0.55 ± 0.18 vs. 0.78 ± 0.31, p < 0.049], parameter 18: the maximum gradient at the upper third of the vagina (posterior) [(kPa/mm, mean ± SD) 0.16 ± 0.05 vs. 0.36 ± 0.28, p < 0.048], and parameter 47: integral force change in the anterior compartment at reflex pelvic muscle contraction (cough) [(N, mean ± SD) 1.61 ± 0.85 vs. 1.97 ± 0.71, p < 0.045]. ConclusionOur study revealed a significant association between the improvement of strength in targeted muscle groups and a reduction in urinary incontinence symptoms. Identifying specific muscles changing PFMT provides valuable insights for specific interventions. Our findings may help to create personalized and targeted interventions to improve the quality of life of women affected by SUI.

A FACILE METHOD TO PRODUCE HIGH-BULK AND HIGH-STRENGTH ROLLED RECONSTITUTED TOBACCO SHEET WITH REFINED TOBACCO CELLULOSE FIBERS

The rolling method is a pivotal means for reconstituted tobacco sheet (RTS) production due to its cost-effectiveness. However, the traditional rolling method is limited by its raw material grinding processes and yields of rolled RTS (RRTS) with subpar strength and bulk. Therefore, it is a challenge to develop a method to produce high-strength and high-bulk RRTS. Here, by replacing traditional raw materials grinding processes with papermaking refining processes, we present a facile and practical method to produce RRTS with elevated bulk and strength. This method separately refines tobacco leaves and stems into long and coarse leave and stem cellulose fibers. These fibers were subsequently reconstructed into RRTS. The detailed process parameters were optimized. The comparative RRTS with flax fibers instead of stem fibers was investigated. The optimal formula of new RRTS was determined. The updated processes, along with the use of refined cellulose fibers, led the RRTS to a significant improvement in strength and bulk, with a 5.3-fold increase in strength, and a 0.7-fold increase in bulk, while smoking qualities were preserved, which surpassed the smoking experience of RRTS with flax fibers. We anticipate this work will enhance the qualities of RTS and facilitate the transition of traditional tobacco industries toward healthier directions.

The effect of chiropractic spinal manipulation on the H-reflex and muscle strength in children with cerebral palsy: A feasibility study

Background Children with cerebral palsy (CP) have deficits in various aspects of motor control, including motor neuron excitability, which can affect muscle strength, gait, and ability to perform activities of daily living. Previous research on chiropractic spinal manipulation in healthy adults, athletes, and a brain-injured population has indicated improvements in motor neuron excitability, muscle strength, and various aspects of motor control. Thus, chiropractic spinal manipulation may improve motor control in children with CP. Methods Children with spastic diplegic CP, aged 8-13 years, were recruited for a randomized, controlled feasibility study. Feasibility was assessed in terms of recruitment strategy and rate, data collection procedures, equipment, intervention, and compliance. Results Three children completed the data collection comprising pre- and post-measurements of the H reflex, V-wave, and muscle strength. The recruitment strategy and rate were not feasible. The data collection procedures were appropriate and complied with, except for the V-wave measurements. The H-reflex threshold decreased and s50 and slope increased in the participants who received chiropractic spinal manipulation; the opposite was seen in the control group. The changes in MVC force were inconsistent between subjects. Conclusion This study answered some important feasibility questions regarding conducting a large-scale randomized controlled study with the same design. Some aspects proved feasible, such as H-reflex recordings, and some aspects, such as recruitment methods and V-wave recordings, need to be altered for future research in this area.

Efficacy of lower limb strengthening exercises based on different muscle contraction characteristics for knee osteoarthritis: a systematic review and network meta-analysis.

While strengthening exercises are recommended for knee osteoarthritis (KOA) treatment, the optimal type of muscle contraction remains unclear, with current research showing conflicting results. This network meta-analysis (NMA) aims to evaluate the efficacy of lower limb strengthening exercises based on different muscle contraction characteristics for KOA patients and provide clinical references. We conducted the NMA following the PRISMA-NMA. A comprehensive search of five databases (PubMed, Web of Science, CENTRAL, Embase, and SPORTDiscus) up to August 2024 identified randomized controlled trials (RCTs) investigating lower limb strengthening exercises in KOA patients. Control groups included receiving usual care, only providing health education, or no intervention at all. Outcomes analyzed included pain, physical function, quality of life, and muscle strength. Forty-one studies (2,251 participants) were included. Twenty-eight studies used rigorous randomization; eighteen reported allocation concealment. All had high performance bias risk due to exercise interventions. Regarding efficacy, isokinetic exercise ranked highest in pain relief (SMD = 0.70, 95% CI: 0.50-0.91, SUCRA = 82.6%), function improvement (SMD = 0.75, 95% CI: 0.57-0.92, SUCRA = 96.1%), and enhancement in muscle strength (SMD = 0.56, 95% CI: 0.34-0.78, SUCRA = 90.1%). Isometric exercise ranked highest in improving quality of life (SMD = 0.80, 95% CI: 0.28-1.31, SUCRA = 90.5%). Mixed strengthening exercise ranked lowest across all outcomes. High-frequency interventions (≥5 times/week) showed superior pain relief compared with low-frequency (≤3 times/week) for isotonic, isometric, and isokinetic exercise. This NMA suggests isokinetic exercise may be most effective for pain, function, and muscle strength in KOA patients, while isometric exercise benefits quality of life most. Mixed strengthening exercise ranked lowest across all outcomes. High-frequency interventions appear more effective than low-frequency ones. These findings support personalized KOA treatment, considering efficacy, accessibility, and patient-specific factors. Study biases, heterogeneity, and other limitations may affect result reliability. Future research should focus on high-quality studies with standardized protocols and analyze dose-response relationships to refine KOA treatment strategies. https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024582525, identifier: CRD42024582525.

Influences of isothermal annealing post‐treatment on mechanical performances in fused deposition modeling manufactured short carbon fibrous PETG and PA composites

AbstractFused deposition modeling (FDM) based large‐area additive manufacturing has advanced significantly, particularly for producing large parts with high‐performance short fibrous composites. To improve the mechanical performance of these manufactured parts, isothermal annealing is often employed as a post‐treatment for FDM‐produced components. Hence, this study examines the impact of isothermal annealing on the mechanical properties of short carbon fiber‐filled Polyamide 12 (PA12‐CF) and polyethylene terephthalate glycol (PETG‐CF). Samples are prepared using a customized high‐extrusion‐rate FDM (HFDM) system with varying key printing parameters (layer height and extrusion width). Three‐point bending tests are employed to assess the bending strength, modulus, and fracture deflection of the samples. Results show that annealing treatment significantly enhances the bending performance of PA12‐CF, with strength and modulus increasing by 27.8% and 31.2%, respectively. In contrast, PETG‐CF exhibits relatively minor improvements in bending strength (8.1%) and modulus (2.7%). Optical microscopy reveals that different printing parameters notably influence the alignment of short carbon fibers, affecting the mechanical properties, while the annealing treatment does not alter these parameter‐dependent trends. Finite element simulations further demonstrate that the presence of carbon fibers contributes to a progressive enhancement of the polymer matrix, which impacts mechanical improvement during annealing.Highlights High‐extrusion‐rate FDM is used to prepare PA12 and PETG composite samples. Annealing improves properties more in semi‐crystalline PA12‐CF samples. Meso‐structural analysis reveals that printing parameters play a crucial role. Short‐carbon‐fiber boosts strengths of the polymer matrix during annealing.

Fracture mechanism and ductility performances of fiber reinforced shotcrete under flexural loading insights from digital image correlation (DIC)

This paper investigates the fracture mechanism and ductility performance of fiber-reinforced shotcrete (FRS) under flexural loading through digital image correlation (DIC) analysis. The focus is on determining the optimal mix design, utilizing recycled and manufactured fibers in shotcrete through four-point bending tests. These tests reveal significant improvements in flexural strength and ductility, as well as crack resistance, attributed to the synergistic effect of both types of fiber in hybrid fiber reinforcement. Notably, the inclusion of recycled fibers from automobile tires enhances mechanical characteristics and impact resistance, contributing to environmental sustainability and cost reduction. DIC analysis offers crucial insights into crack initiation and propagation in shotcrete, highlighting the impact of fiber reinforcement on crack patterns. Manufactured fibers delay crack onset effectively, while hybridization enhances fracture characteristics, offering improved crack control and flexural strength. The study underscores the potential of hybrid fiber mixes for enhancing structural performance in tunnel support applications, emphasizing the synergistic effect of hybrid of different fiber types. Overall, the research contributes to advancing understanding of fracture behavior in fiber-reinforced shotcrete and provides practical insights for optimizing mix designs to achieve superior mechanical properties and durability.

Evolution of Al2Cu Secondary Phase and Precipitation Strengthening of 2219 Al Alloy with Ultrasonic Melt Treatment, Hot Rolling, and Solution Aging

This study aims to clarify the combined effect of ultrasonic melt treatment (UST), hot rolling and solution aging (HRSA) on the evolution of the Al2Cu secondary phase in 2219 Al alloy toward the optimization of its mechanical properties for high‐performance structural applications. The results show that UST is beneficial for modifying the morphology and reducing the size of the secondary phase (by an average of 17.9%), and conducive to increasing the Cu content in the Al matrix (by an average of 37.5%) during solidification. The genetic effects of UST on the microstructure generated during HRSA result in denser and finer θ′/θ″ Al2Cu particles precipitating in the α‐Al matrix, with a 62.1% increase in the precipitates volume in the HRSA sample. Theoretical calculations confirm that precipitation strengthening is the predominant mechanism for strength improvement of 2219 Al alloy after UST and HRSA. The ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) of the HRSA alloy without UST are 329, 214 MPa, and 11.9%, respectively, while these parameters are increased by 12.5% (to 370 MPa), 9.8% (to 235 MPa), and 17.6% (to 14.0%) for the UST alloy, respectively.