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The unusual combination of the fundamentally contradictory properties of high tensile strength and high fracture toughness found in maraging steel makes it well suited for safety-critical applications that require high strength-to-weight materials. In certain instances, additive manufacturing (AM) has produced materials that may be desirable for safety-critical applications where impact toughness is a key property, such as structural parts for the aerospace industry or armor plates for military applications. Understanding the influence of process parameters and defect structure on the properties of maraging steel parts produced via laser powder bed fusion (LPBF) is a fundamental step towards the broader use of AM technologies for more demanding applications. In this research, the impact energy of V-notched specimens made of 1.2709 maraging steel produced by LPBF was determined via Charpy impact testing. Specimens were produced using different processing parameter sets. By combining the process parameters with the porosity values of the parts, we demonstrate that an almost full prediction of the impact properties can be achieved, paving the way for significantly reducing the expenses of destructive testing. [ABSTRACT FROM AUTHOR]

Background: Pes cavus is a multiplanar foot deformity with an abnormal plantar pressure distribution and an overhigh medial longitudinal arch (MLA). Its causes are complex. In the past, people have usually focused on clinical surgery for pes cavus. However, this is not necessarily the best choice for some patients with non-ongoing or mild symptoms. In the 21st century, studies have just begun to focus on assistive devices intervention for pes cavus, which has been proven to be an effective non-surgical treatment. However, the effectiveness of assistive devices for patients with arched feet of any etiology has not been evaluated and evidence-based guidelines for clinical treatment options are lacking. Methods: A systematic review and network meta-analysis were performed, employing a comprehensive search across the databases of Web of Science, PubMed, as well as Scopus. The selected studies adhered to specific eligibility criteria, which included: (1) involving patients with pes cavus; (2) interventions with assistive devices; and (3) outcome measures of plantar pressure distribution and anatomical characteristics (MLA). Meanwhile, the standard mean difference was selected as the effect size. Results: A total of three studies were selected, and the authors achieved an agreement on the risk of bias with a kappa value equal to 0.74. According to the results of network meta-analysis, customized foot orthotics compared to other devices (lace-up ankle-support brace, semirigid brace) demonstrated the highest likelihood of being the most effective in optimizing plantar-pressure distribution among pes cavus patients. On the other hand, wearing hard custom foot orthotics compared to other devices (soft custom foot orthotics, off-the-shelf orthotics) showed the greatest potential in improving the medial longitudinal arch (MLA) of pes cavus patients. Discussion: Although becoming better than wearing regular footwear, wearing lace-up ankle-support braces or semirigid braces might not be optimal choices for treatments of pes cavus with the potential mechanism that the internal force created by the fixation of the proximal joint might be much less than the ground reaction force loaded on the distal segments that touch the ground. It could be concluded that foot orthotics show great potential in treating pes cavus under non-surgical conditions. This systematic review could provide valuable evidence for future research and clinical practice. Other: The PROSPERO Registration Number is CRD42022349687.

Payloads for light unmanned free balloons must meet several safety requirements such as being able to protect the inner electronics in order to extract scientific data and to reduce the chance of inflicting personal injury in case of an accidental fall. This article proposes a novel payload structure, which exhibits the form of a dodecahedron. The actual form was determined by carrying out theoretical drop tests on different polyhedrons using the finite element method (FEM). From the simulations, it could be deduced that the dodecahedron was the optimal choice, since the duration of the impact was longer, while the impact force was slightly lower. The payload was produced by additive technologies; therefore, after performing tensile tests on probable materials, PLA was selected as the optimal candidate. The theoretical results about the dodecahedron's ability were validated by laboratory and real-life drop tests, where the new payload was subjected to 56% less impact force under a 78% longer collision time compared to a classic, rectangular cuboid design. Based on these tests, it was demonstrated that the new structure is safer and it is applicable. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this study was to evaluate the effect of runninginduced fatigue on the characteristic asymmetry of running gait and to identify non-linear differences in bilateral lower limbs and fatigued gait by building a machine learning model. Methods: Data on bilateral lower limb three-dimensional ground reaction forces were collected from 14 male amateur runners before and after a running-induced fatigue experiment. The symmetry function (SF) was used to assess the degree of symmetry of running gait. Statistical parameter mapping (Paired sample T-test) algorithm was used to examine bilateral lower limb differences and asymmetry changes pre- and post-fatigue of time series data. The support vector machine (SVM) algorithm was used to recognize the gait characteristics of both lower limbs before and after fatigue and to build the optimal algorithm model by setting different kernel functions. Results: The results showed that the ground reaction forces were asymmetrical (SF > 0.5) both pre-and post-fatigue and mainly concentrated in the medial-lateral direction. The asymmetry of the medial-lateral direction increased significantly after fatigue (p < 0.05). In addition, we concluded that the polynomial kernel function could make the SVM model the most accurate in classifying left and right gait features (accuracy of 85.3%, 82.4%, and 82.4% in medial-lateral, anteriorposterior and vertical directions, respectively). Gaussian radial basis kernel function was the optimal kernel function of the SVM algorithm model for fatigue gait recognition in the medial-lateral and vertical directions (accuracy of 54.2% and 62.5%, respectively). Moreover, polynomial was the optimal kernel function of the anterior-posterior direction (accuracy = 54.2%). Discussion: We proved in this study that the SVM algorithm model depicted good performance in identifying asymmetric and fatigue gaits. These findings can provide implications for running injury prevention, movement monitoring, and gait assessment. [ABSTRACT FROM AUTHOR]

Introduction: Footwork is one of the training contents that table tennis players and coaches focus on. This study aimed to gain a thorough understanding of the muscle activity of the table tennis footwork and creating a musculoskeletal model to investigate the muscle forces, joint kinematic, and joint kinetic characteristics of the footwork during topspin forehand stroke. Methods: Six male table tennis athletes (height: 171.98 ± 4.97 cm; weight: 68.77 ± 7.86 kg; experience: 10.67 ± 1.86 years; age: 22.50 ± 1.64 years) performed chasse step and one-step footwork to return the ball from the coach by topspin forehand stroke. The kinematics, kinetics, and muscle activity of the lower limb were recorded by the motion capture, force platform, and Electromyography (EMG) system. Statistical parametric mapping (SPM) analysis was used to investigate any difference between the chasse step and one-step footwork during the stroke. Results and Conclusion: The muscle force of the biceps femoris long head (p < 0.001), lateral gastrocnemius (p < 0.001), vastus lateralis (p < 0.001), vastus medial (p < 0.001), rectus femoris (p < 0.001), and tibia anterior (p < 0.001) of the chasse step were significantly greater than the one-step footwork during the early stroke phase (stance). At the end of the stroke phase (push-off), the muscle force of the biceps femoris long head (p < 0.001), medial gastrocnemius (p < 0.001), lateral gastrocnemius (p < 0.001), rectus femoris (p < 0.001), and tibias anterior (p < 0.001) in the chasse step footwork was significantly greater than the one-step footwork. The muscle force of the ankle plantar flexor and valgus muscle groups in the one-step was significantly greater than in the chasse step. Besides, the moment and angle of hip flexion (p = 0.001) and axial rotation (p = 0.009) were significantly greater for the chasse step than the one-step footwork, as well as the ankle plantar-flexion angle (p < 0.001) and moment (p < 0.001) of the one-step footwork were significantly higher than the chasse step footwork. The results of this study can be applied to movement control and injury prevention in table tennis footwork. [ABSTRACT FROM AUTHOR]