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ABSTRACT Objectives The biomechanical mechanism of brace intervention on bone, muscle, and disc should be comprehensively considered for AIS patients. We aimed to developmentally construct a musculoskeletal finite element model of adolescent idiopathic scoliosis to simulate the coupling of corrective forces and analyze the mechanical properties of bone, muscle, and disc. Investigateing, more effective clinical interventions to break the vicious cycle of patients during growth. Methods A finite element model, including muscle, bone, and disc, was established using computed tomography data of a patient with RigoA3 adolescent idiopathic scoliosis. The three‐point force coupling, antigravity, and bending effects of the Chêneau brace were simulated, and the correction force of the secondary lumbar bend was gradually reduced while observing the mechanical characteristics of bone, muscle, and disc. The correction force in line with symmetrical spine growth was comprehensively evaluated. Results The correction rate of the main thoracic (MT) curve, the intervertebral space height on the concave side of the vertebrae at the apex, and the stress ratio of the intervertebral discs were optimal when the maximum corrective pressure threshold was reached. However, the proximal thoracic (PT) curve was aggravated and the axial forces on the concave side were unbalanced. At this time, the biomechanical performance of the model is also not optimal. The correction rate of the Cobb Angle of the MT curve decreased with the decrease of the correction pressure in the lumbar region. When reduced to 25% of the maximum threshold, the convex side of disc stress, intervertebral space, and muscle axial force is more in line with the biomechanical mechanism of correction and can avoid sacrificing the PT curve. Conclusions Downward adjustment of the corrective force to the secondary lumbar curve, using the Chêneau brace, results in better primary thoracic curvature mechanics in the musculoskeletal finite element model, suggesting that breaking the vicious cycle of scoliosis progression to guide benign spinal growth is beneficial.

Abstract Background Knee osteoarthritis (KOA) is a prevalent and debilitating condition that markedly affects the sit-to-stand (STS) activity of patients, a prerequisite for daily activities. Biomechanical recognition of movements in patients with mild KOA is currently attracting attention. However, limited studies have been conducted solely on the observed differences in sagittal plane movement and muscle activation. Aim This study aimed to identify three-dimensional biomechanical and muscle activation characteristics of the STS activity in patients with mild KOA. Methods A cross-sectional study was conducted to observe the differences between patients with mild KOA and a control group (CG). It was conducted to observe the differences in muscle activation, including root mean square (RMS%) and integrated electromyography (items), kinematic parameters like range of motion (ROM) and maximum angular velocity, as well as dynamic parameters such as joint moment and vertical ground reaction force (vGRF). Results Patients with mild KOA had a higher body mass index and longer task duration. In the sagittal plane, patients with KOA showed an increased ROM of the pelvic region, reduced ROM of the hip–knee–ankle joint, and diminished maximum angular velocity of the knee–ankle joint. Furthermore, patients with KOA displayed increased knee–ankle joint ROM in the coronal plane and decreased ankle joint ROM in the horizontal plane. Integrated vGRF was higher in both lower limbs, whereas the vGRF of the affected side was lower. Furthermore, patients showed a decreased peak adduction moment (PADM) and increased peak external rotation moment in the knee joint and smaller PADM and peak internal rotation moment in the ankle joint. The affected side exhibited decreased RMS% and iEMG values of the gluteus medius, vastus medialis, and vastus lateralis muscles, as well as a decreased RMS% of the rectus femoris muscle. Conversely, RMS% and iEMG values of the biceps femoris, lateral gastrocnemius, and medial gastrocnemius muscles were higher. Conclusion The unbalanced activation characteristics of the anterior and posterior muscle groups, combined with changes in joint moment in the three-dimensional plane of the affected joint, may pose a potential risk of injury to the irritated articular cartilage.

Abstracts: The effects of solution time and aging temperature on the microstructure and properties of C17300 beryllium copper alloy wire were studied by means of SEM, XRD, electronic universal tester and resistance tester. The results show that after solution treatment, the deformed twin structure disappears and the distorted crystal grows into equiaxed crystal. The optimum solution time is 90 min, and the hardness and resistivity are 115HV and 1.13 × 10−7 Ω m respectively. The optimum solution time is 90 min, and the hardness and resistivity are 115HV and 9.52 × 10−7 Ω m respectively. When the aging temperature is increased from 260 °C to 340 °C, the amount of grain boundary reaction is increased from 3.84% to 17.05%, and the precipitated phase changes from point to tumor-like distribution. When the aging temperature rises to 320 °C, the mechanical properties are the best, with tensile strength of 1192.86 MPa, hardness of 373.81HV and elongation of 5.16%. With the increase of aging temperature, the work hardening rate gradually increases, the number of dimples and micropores on the fracture surface decreases, and the granular precipitates at the bottom of dimples increase. In summary, the differences of microstructure and mechanical properties of beryllium bronze at different solution time and aging temperature are compared, which provides some basis for preparing high strength beryllium copper alloy microwires.

In order to design Cu-Sn alloys with excellent overall performance, the structural stability, mechanical properties, and electronic structure of X-doped Cu-Sn alloys were systematically calculated using first-principles calculations. The calculation results of the cohesive energy indicate that the Cu-Sn-X structures formed by X atoms (X = Ag, Ca, Cd, Mg, Ni, Zr) doping into Cu-Sn can stably exist. The Cu-Sn-Ni structure is the most stable, with a cohesive energy value of −3.84 eV. Doping of X atoms leads to a decrease in the bulk modulus, Possion’s ratio and B/G ratio. However, doping Ag and Ni atoms can improve the shear modulus, Young’s modulus, and strain energy of the dislocation. The doping of Ni has the highest enhancement on shear modulus, Young’s modulus, and strain energy of the dislocation, with respective values as follows: 63.085 GPa, 163.593 GPa, and 1.689 W/J·m−1. The analysis of electronic structure results shows that the covalent bond between Cu and X is the reason for the performance differences in Cu-Sn-X structures.

Abstract Background In our previous study, activin B in combination with ADSCs enhances skin wound healing. However, the underlying molecular mechanisms are not well studied. Cdc42 is recognized to play a critical role in the regulation of stem cells. Methods Pull-down assay was performed to investigate the activity of Cdc42. The dominant-negative mutant of Cdc42 (Cdc42N17) was used to explore the role of Cdc42 in activin B-induced ADSCs migration, proliferation, and secretion in vitro. Cdc42N17-transfected ADSCs were injected into a full-thickness excisional wound model to explore their efficiency in wound healing in vivo. The wound healing efficacy was evaluated by the wound closure rates and histological examination. The neovascularization and wound contraction were detected by immunohistochemistry staining of CD31 and α-SMA. Finally, the underlying mechanisms were explored by RNA sequencing. Results Cdc42N17 inhibited ADSCs migration, proliferation, and secretion induced by activin B. Furthermore, Cdc42N17-transfected ADSCs inhibited the wound closure rate and suppressed the expression of CD31 and α-SMA induced by activin B in vivo. The RNA sequencing showed that the differentially expressed genes in Cdc42N17-transfected ADSCs versus ADSCs were associated with cell migration, proliferation, and adhesion. Further study revealed that the Cdc42-Erk-Srf pathway was required for activin B-induced proliferation in ADSCs. Conclusions Our study indicates that Cdc42 plays a crucial role in ADSCs-mediated skin wound healing induced by activin B. Graphical Abstract

Tonal working memory load refers to the number of pitches held in working memory. It has been found that different verbal working memory loads have different neural coding (local neural activity pattern). However, whether there exists a comparable phenomenon for tonal working memory load remains unclear. In this study, we used a delayed match-to-sample paradigm to evoke tonal working memory. Neural coding of different tonal working memory loads was studied with a surface space and convolution neural network (CNN)-based multivariate pattern analysis (SC-MVPA) method. We found that first, neural coding of tonal working memory was significantly different from that of the control condition in the bilateral superior temporal gyrus (STG), supplement motor area (SMA), and precentral gyrus (PCG). Second, neural coding of nonadjacent tonal working memory loads was distinguishable in the bilateral STG and PCG. Third, neural coding is gradually enhanced as the memory load increases. Finally, neural coding of tonal working memory was encoded in the bilateral STG in the encoding phase and shored in the bilateral PCG and SMA in the maintenance phase.

In light of the fact that tungsten wire is gradually replacing high-carbon steel wire as a diamond cutting line, it is particularly important to study tungsten alloy wire with better strength and performance. According to this paper, in addition to various technological factors (powder preparation, press forming, sintering, rolling, rotary forging, annealing, wire drawing, etc.), the main factors affecting the properties of the tungsten alloy wire are the composition of the tungsten alloy, the shape and size of the powder, etc. Combined with the research results in recent years, this paper summarizes the effects of changing the composition of tungsten materials and improving the processing technology on the microstructure and mechanical properties of tungsten and its alloys and points out the development direction and trend of tungsten and its alloy wires in the future.

The performance of rolling parameters and annealing processes on the microstructure and properties of Cu strip were studied by High Precision Rolling Mill, FIB, SEM, Strength Tester, and Resistivity Tester. The results show that with the increase of the reduction rate, coarse grains in the bonding Cu strip are gradually broken and refined, and the grains are flattened when the reduction rate is 80%. The tensile strength increased from 248.0 MPa to 425.5 MPa, while the elongation decreased from 8.50% to 0.91%. The growth of lattice defects and grain boundary density results in an approximately linear increase in resistivity. With the increase of annealing temperature to 400 °C, the Cu strip recovers, and the strength decreased from 456.66 MPa to 220.36 MPa while the elongation rose from 1.09% to 24.73%. The tensile strength and elongation decreased to 192.2 MPa and 20.68%, respectively, when the annealing temperature was 550 °C. The trend of yield strength of the Cu strip was basically the same as that of tensile strength. The resistivity of the Cu strip decreased rapidly during a 200~300 °C annealing temperature, then the trend slowed, and the minimum resistivity was 3.60 × 10−8 Ω·m. The optimum tension range annealing was 6–8 g; less or more than that will affect the quality of the Cu strip.