Explore the vast range of titles available.

Tibial stress fractures are a common overuse injury resulting from the accumulation of bone microdamage due to repeated loading. Researchers and wearable device developers have sought to understand or predict stress fracture risks, and other injury risks, by monitoring the ground reaction force (GRF, the force between the foot and ground), or GRF correlates (e.g., tibial shock) captured via wearable sensors. Increases in GRF metrics are typically assumed to reflect increases in loading on internal biological structures (e.g., bones). The purpose of this study was to evaluate this assumption for running by testing if increases in GRF metrics were strongly correlated with increases in tibial compression force over a range of speeds and slopes. Ten healthy individuals performed running trials while we collected GRFs and kinematics. We assessed if commonly-used vertical GRF metrics (impact peak, loading rate, active peak, impulse) were strongly correlated with tibial load metrics (peak force, impulse). On average, increases in GRF metrics were not strongly correlated with increases in tibial load metrics. For instance, correlating GRF impact peak and loading rate with peak tibial load resulted in r = -0.29±0.37 and r = -0.20±0.35 (inter-subject mean and standard deviation), respectively. We observed high inter-subject variability in correlations, though most coefficients were negligible, weak or moderate. Seventy-six of the 80 subject-specific correlation coefficients computed indicated that higher GRF metrics were not strongly correlated with higher tibial forces. These results demonstrate that commonly-used GRF metrics can mislead our understanding of loading on internal structures, such as the tibia. Increases in GRF metrics should not be assumed to be an indicator of increases in tibial bone load or overuse injury risk during running. This has important implications for sports, wearable devices, and research on running-related injuries, affecting >50 scientific publications per year from 2015-2017.

HighlightsA dynamic constitutive model for rock materials suited to dynamic cyclic loading was established.The numerical tests on a hard rock under true triaxial dynamic cyclic loading with different loading rates were conducted.The dynamic deformation and mechanical properties of a hard rock were studied.

Most of the existing researches on energy evolution in the process of rock deformation and failure mainly revolve around a specific stage (before or after the peak). However, there are few studies involving the impacts of lithology and loading rate on the energy evolution in the whole process from deformation to failure, especially the studies on non-linear characteristics of rock energy, which is the frontier of study on the mechanism of rock failure. In this context, this study further explores the influencing rule of lithology and loading rate on the energy evolution process of loaded rock. By employing the MTS 815 rock mechanics test system and conducting 18 groups of tests on yellow sandstone, limestone and marble, the research reveals the evolution process and distribution law of elastic energy resilience density along with the stress. Then the micro-mechanism of accumulation and dissipation of rock energy are analyzed. A non-linear evolution model (Logistic equation) is proposed that demonstrates how the energy density of loaded rock changes with axial stress. This model can also explore the bifurcation and chaos characteristics of rock energy evolution, and further reveals the rule that the iterative growth factor of energy density changes with lithology, stress level and loading rate. The results are conducive to deepening the understanding on the differences in engineering characteristics of rocks with different lithologies, and play a guiding role in the prevention and control against dynamic disasters of rocks in the engineering field.

As a state-of-the-art computational method for simulating rock fracturing and fragmentation, the combined finite-discrete element method (FDEM) has become widely accepted since Munjiza (2004) published his comprehensive book of FDEM. This study developed a general-purpose graphic-processing-unit (GPGPU)-parallelized FDEM using the compute unified device architecture C/C ++ based on the authors’ former sequential two-dimensional (2D) and three-dimensional (3D) Y-HFDEM IDE (integrated development environment) code. The theory and algorithm of the GPGPU-parallelized 3D Y-HFDEM IDE code are first introduced by focusing on the implementation of the contact detection algorithm, which is different from that in the sequential code, contact damping and contact friction. 3D modelling of the failure process of limestone under quasi-static loading conditions in uniaxial compressive strength (UCS) tests and Brazilian tensile strength (BTS) tests are then conducted using the GPGPU-parallelized 3D Y-HFDEM IDE code. The 3D FDEM modelling results show that mixed-mode I–II failures are the dominant failure mechanisms along the shear and splitting failure planes in the UCS and BTS models, respectively, with unstructured meshes. Pure mode I splitting failure planes and pure mode II shear failure planes are only possible in the UCS and BTS models, respectively, with structured meshes. Subsequently, 3D modelling of the dynamic fracturing of marble in dynamic Brazilian tests with a split Hopkinson pressure bar (SHPB) apparatus is conducted using the GPGPU-parallelized 3D HFDEM IDE code considering the entire SHPB testing system. The modelled failure process, final fracture pattern and time histories of the dynamic compressive wave, reflective tensile wave and transmitted compressive wave are compared quantitatively and qualitatively with those from experiments, and good agreements are achieved between them. The computing performance analysis shows the GPGPU-parallelized 3D HFDEM IDE code is 284 times faster than its sequential version and can achieve the computational complexity of O(N). The results demonstrate that the GPGPU-parallelized 3D Y-HFDEM IDE code is a valuable and powerful numerical tool for investigating rock fracturing under quasi-static and dynamic loading conditions in rock engineering applications although very fine elements with maximum element size no bigger than the length of the fracture process zone must be used in the area where fracturing process is modelled.

Understanding material behavior is key to discovering innovative applications in any field. Regardless of the exciting mechanical properties of polyurea, there has been a limited effort in studying the use of polyurea for structural retrofit and strengthening applications. This study aims to understand the behavior of polyurea under different tensile loading conditions to provide critical information towards enabling the future use of polyurea in structural applications. Several standard coupons are tested under various tensile loading conditions to understand the mechanical behavior of eight different commercial polyureas. The study provides the full stress–strain characteristic curves that can be used for constitutive modeling purposes. The results show that polyurea has a wide range of properties from low strength flexible nature to high strength rigid nature. All tested polyureas displayed some level of rate dependency, i.e., ultimate strength is a function of loading rates. The high-strength polyureas tested only show slight rate dependency and good strength retention under cyclic and fatigue tensile loading, suggesting that polyureas have promising mechanical properties for potential structural applications.

Phosphogypsum is a solid waste with great environmental stockpile pressure produced by the wet production of phosphoric acid. Although there are various methods to purify and utilize phosphogypsum, the means for environmentally friendly, low energy consumption, and high value-added utilization still need to be further explored. Here, CaSO4·2H2O crystal was directly purified and regulated from phosphogypsum by using the anti-solvent method. The antisolvent can be adsorbed in the c-axis direction of the crystal and further inhibit the growth rate in this direction, resulting in a change in the morphology of the crystal. By adjusting the polarity and chain length of the anti-solvent, the morphology of CaSO4·2H2O crystal can change from butterfly-like flake crystals to hexagonal prism-like crystals. When n-propanol with long chain was used as the anti-solvent, the morphology of the CaSO4·2H2O crystal showed a hexagonal prism with a specific surface area of 19.98 m2/g and a Cu2+ loading efficiency of 52.67%. The encouraging results open up new possibilities for the application of phosphogypsum.

 With the vigorous development of the global maritime industry, rapid ship loading planning is of great significance for improving transportation efficiency and reducing costs. However, traditional loading planning methods often find it difficult to achieve optimization in the face of large-scale and complex tasks. In order to improve the planning effectiveness of ship rapid loading planning, this study uses simulated annealing algorithm to improve genetic algorithm and obtain optimized algorithm, which is applied to the ship rapid loading planning model. The algorithm comparison results showed that compared with the comparison algorithm, the loss value and prediction fitting coefficient of the optimized genetic algorithm were 0.003 and 0.9632, respectively, which were better than the comparison algorithm. In addition, in the empirical analysis of optimizing genetic algorithms, it was found that the minimum and maximum planning satisfaction rates of SA-GA algorithm were 82.3% and 87.2%, respectively, which were superior to the comparative algorithm. Results indicate that the optimized genetic algorithm has good planning performance in ship rapid loading planning and has good application prospects. This study provides new solutions and methods for optimization problems in the field of ship transportation.

Rock elasticity varies with both mechanical loading and moisture content. Studies to date have only examined each effect independently, although moisture interactions with pore walls are likely coupled to mechanical stress. Here, we present experimental data specifically collected in sandstone and granite under simultaneous control of cyclic loading alongside ambient humidity approaching saturated vapor. Adsorption can account for 40% reduction in Young's modulus, which reduces to <${< } $ 10% as uniaxial stress increases from below 1 MPa to below the elastic limit. The observation is explained by a micromechanical model linking grain‐scale contact stiffness to pore‐scale vapor adsorption, quantitatively capturing coupled stress‐induced stiffening and adsorption‐induced softening. The coupled behavior is interpreted as adsorption‐induced softening becoming inhibited under greater mechanical loads. Our results suggest the coupled effects are strongest at overburden stresses between 3.3 and 10.6 MPa (140–450 m) in sandstone and 6–30.3 MPa (235–1,200 m) in granite.

Enhanced Recovery after Surgery (ERAS) with sole carbohydrate (CHO) loading and postoperative early oral feeding (POEOF) shortened the length of postoperative (PO) hospital stays (LPOHS) without increasing complications. This study aimed to examine the impact of ERAS with preoperative whey protein-infused CHO loading and POEOF among surgical gynecologic cancer (GC) patients. There were 62 subjects in the intervention group (CHO-P), which received preoperative whey protein-infused CHO loading and POEOF; and 56 subjects formed the control group (CO), which was given usual care. The mean age was 49.5 ± 12.2 years (CHO-P) and 51.2 ± 11.9 years (CO). The trial found significant positive results which included shorter LPOHS (78.13 ± 33.05 vs. 99.49 ± 22.54 h); a lower readmission rate within one month PO (6% vs. 16%); lower weight loss (−0.3 ± 2.3 kg vs. −2.1 ± 2.3 kg); a lower C-reactive protein–albumin ratio (0.3 ± 1.2 vs. 1.1 ± 2.6); preserved muscle mass (0.4 ± 1.7 kg vs. −0.7 ± 2.6 kg); and better handgrip strength (0.6 ± 4.3 kg vs. −1.9 ± 4.7 kg) among CHO-P as compared with CO. However, there was no significant difference in mid-upper arm circumference and serum albumin level upon discharge. ERAS with preoperative whey protein-infused CHO loading and POEOF assured better PO outcomes.

Background Implant placement in the posterior maxilla is challenging, so modifications of the surgical techniques were introduced to overcome these challenges. The undersized drilling technique uses a final drill smaller than the diameter of the implant. The single drilling technique is a simplified method where the osteotomy is made using a single drill without sequential widening. This study was directed to evaluate the peri-implant bone behavior of the undersized drilling technique versus the single drilling technique of immediately loaded dental implants inserted in the posterior maxilla. Patients and methods 32 patients were selected for prosthetic replacement of a missing maxillary posterior single tooth by an immediately loaded dental implant and divided randomly into two equal groups. In Group I: 16 patients received 16 implants using the undersized drilling technique, while in Group II: 16 patients received 16 implants using the single drilling technique. Insertion torque, implant stability, modified sulcus bleeding index (mBI), peri-implant probing depth, bone density, and marginal bone height were evaluated for both groups. Statistical analysis was made for clinical and radiographic data. Results 32 implants were inserted in the posterior maxilla. During a 12-month follow-up, every dental implant was successful with no complications. Both techniques showed high insertion torque (≥ 35 Ncm) and primary stability (> 70 ISQ) with no significant difference between the two groups ( P  > 0.05). Also, there were no significant differences between the study groups regarding peri-implant soft tissue health, bone density, and marginal bone loss ( P  > 0.05). Conclusion Both techniques revealed comparable, promising clinical and radiographic outcomes over a 12-month post-loading follow-up period when the immediate loading protocol was used in the posterior maxilla, where bone density is poor, but preparing the implant bed using the single drilling technique offers several merits for both the patient and clinician. In addition to avoiding excessive heat generation, mechanical damage, and high frictional forces during drilling procedures, surgical operations, and surgical site exposure take less time. Trial registration Clinical-Trials.gov PRS ( https://register.clinicaltrials.gov ) had this study registered under the identifier number. NCT06770231 on 01/01/2025.