Direction Of Force Research Articles

Interannual Time‐Scale Dynamics of Deep Cross‐Equatorial Overturning in the Indian Ocean

AbstractThe Deep Cross‐Equatorial Cell (DCEC) is the primary branch of Indian Ocean Meridional Overturning Circulation (MOC) in the tropical Indian Ocean, essential for energy redistribution, water exchange, and diapycnal mixing. However, the mechanisms behind its interannual variability remain limited. This study utilized two reanalysis data sets and a series of ocean model experiments with a Hybrid Coordinate Ocean Model and a Linear Ocean Model to investigate the underlying mechanisms. Model experiments highlight the critical role of direct local wind forcing and eastern boundary waves induced by remote equatorial wind forcing in influencing the DCEC variability. Specifically, through the first mode of baroclinic dynamics, direct wind forcing initiates reverse meridional flow at the DCEC core (around 8°S) in both surface and deep ocean layers, leading to interannual variations of the DCEC. During transitions of climate modes like ENSO and Indian Ocean Dipole from positive to negative phases, both positive and negative DCEC anomalies intensify. In addition to direct local wind forcing, the delayed‐time Rossby waves reflected from the eastern boundary excited by the equatorial easterly wind in the previous year make substantial contributions (37.8%). The interplay of faster baroclinic Rossby waves at lower latitudes and slower baroclinic Rossby waves at higher latitudes alters the basin‐wide pressure gradient, ultimately amplifying interannual DCEC anomalies in the subsequent year.

Impacts of Thunderstorm-Generated Gravity Waves on the Ionosphere-Thermosphere Using TIEGCM-NG/MAGIC Simulations and Comparisons With GNSS TEC, ICON, and COSMIC-2 Observations.

We use the TIEGCM-NG nudged by MAGIC gravity waves to study the impacts of a severe thunderstorm system, with a hundred tornado touchdowns, on the ionospheric and thermospheric disturbances. The generated waves induce a distinct concentric ring pattern on GNSS TIDs with horizontal scales of 150-400km and phase speeds of 150-300m/s, which is well simulated by the model. The waves show substantial vertical evolution in period, initially dominated by 0.5hr at 200km, shifting to 0.25hr and with more higher-frequency waves appearing at higher altitudes (∼400km). The TADs reach amplitudes of 100m/s, 60m/s, 80K, and 10% in horizontal winds, vertical wind, temperature, and relative neutral density, respectively. Significantly perturbations in electron density cause dramatic changes in its nighttime structure around 200km and near the EIA crest. The concentric TIDs are also simulated in ion drifts and mapped from the Tornado region to the conjugate hemisphere likely due to neutral wind-induced electric field perturbations. The waves manage to impact the ionosphere at altitudes of ICON and COSMIC-2, which pass through the region of interest on a total of 8 separate orbits. In situ ion density observations from these spacecrafts reveal periodic fluctuations that frequently show good agreement with the TIEGCM-NG simulation. The O+ fraction observations from ICON indicate that the density fluctuations are the result of vertical transport of the ions in this region, which could result from either direct forcing by neutral winds or electrodynamic coupling.

Exploring the Impact of Force Direction and Phase on Bone Conduction Hearing with Bone Conduction Actuator

A comprehensive understanding of the effects of bone conduction (BC) input force is essential for elucidating BC hearing mechanisms. However, this area remains underexplored due to the inherent difficulties in controlling input forces when BC transducers are anchored to the bone. In this study, the effects of both unilateral and bilateral BC input forces were investigated using a three-dimensional finite element (FE) model of the human head, which allows precise manipulation of input forces. For unilateral input, 16 distinct directions were created by combining eight in-plane vectors with two tilt angles based on the normal direction of the input force location, and the resulting promontory velocities were compared. Although the magnitude differences between input directions remained within 10 dB, anti-resonance shifts were observed between 1 and 3 kHz. In the bilateral case, phase differences of 0°, 90°, and 180° were applied between input forces at the right and left mastoid positions, and basilar membrane velocities were compared to examine the complex interactions between input forces. These findings provide deeper insights into the effects of input force direction and phase on BC hearing, advancing the understanding of BC hearing mechanisms.

Impedance for Assistance: Upper-Limb Assistive Soft Robotic Suit Using Linked-Layer Jamming Mechanisms.

Wearable robots, especially those composed of soft materials, are increasingly attracting interest due to their comfort, ease of donning and doffing, and their ability to provide assistance across various applications. In wearable robotics, striking a balance between ensuring low impedance for wearer comfort and providing sufficient assistive force is a notable design challenge. In this study, we propose exploiting impedance variation in accordance with the types of muscle contraction in the human body. Particularly in eccentric muscle contraction, the impedance can help reduce the muscular load, since it exerts force in the same direction as the muscles. To utilize the relation, we proposed a linked-layer jamming mechanism, which adjusts its impedance largely in various directions. This mechanism allows not only a broad variable range of impedance in multiple rotation directions but also directional torque design, even when equipped in human multi-degree-of-freedom (DoF) joints. By constructing a wearable robot prototype equipped with the proposed linked-layer jamming mechanisms, the effectiveness of this impedance-based assistance approach was confirmed through experiments. The findings from this study present new possibilities in wearable robot design, showing that suitably amplified impedance can assist human motion, potentially enhancing task efficiency and lowering injury risk. This work thus offers a new perspective for researchers in the field of wearable robots, demonstrating that impedance, often minimized in existing designs, can be utilized beneficially when properly amplified.

Force density induced by preferential adsorption in a near-critical binary fluid mixture subject to the Soret effect.

We assume that two parallel plates are immersed in a binary fluid mixture lying in the one-phase region near the demixing critical point and that the surface of each plate attracts the mixture components differently via short-range interactions. It is known that the composition inhomogeneity caused by the difference can induce a force exerted on the plate at equilibrium. In the present study, we investigate how a temperature gradient imposed vertically on the plates changes the induced force by calculating the composition profile subject to the Soret effect. Numerically solving the derived differential equation, we show that a temperature gradient within the critical regime can change the force distinctly from its equilibrium value and can make the force direction opposite to the one at equilibrium.

Understanding the influence of configurations and intermolecular interaction on thermomechanical and dynamics properties of polymer–clay nanocomposites via molecular dynamics simulations

AbstractPolymer‐clay nanocomposites (PCNs) have emerged as highly versatile structural materials that possess exceptional thermomechanical and dynamic properties, all the while retaining their inherent attributes of being lightweight and optically clear. The fabrication of nanocomposites involves the incorporation of carefully calibrated quantities of clay nanofillers into polymer matrixes. Current research expands upon existing coarse‐grained (CG) models of nanoclay and poly (methyl methacrylate) (PMMA) and utilize molecular dynamics simulations to methodically explore the thermomechanical characteristics of PCNs. Specifically, the effects of exfoliated and stacked configurations of nanoclays, as well as variations in intermolecular interactions between the nanoclay and polymer constituents were tested. Tensile and shear simulations, as well as interfacial behaviors, are conducted. The intermolecular interaction could have significant influences on Shear Modulus and Young's Modulus, and those influences have their characteristics due to different configurations and different force directions, such as in most cases, exfoliated structures exhibit higher mechanical modulus compared with stacked configurations at varying interaction strengths. Additionally, in the in‐plane direction, they demonstrate stronger resistance effects compared with the out‐of‐plane direction. The interaction between PMMA and nanoclay slows down the global dynamics of PMMA, with a stronger effect observed for higher interaction strength. The impact of nanoclay on the segmental dynamics of PMMA decreases as we move away from the nanoclay layers toward the pure PMMA matrix. These findings provide molecular insights into the arrangement of components in PCNs during deformation and highlight the significance of nanoclay and the interface in determining their mechanical and dynamic properties.Highlights Variation patterns of mechanical modulus with interactions and configurations. The property difference in mechanical modulus due to configurations. Positive correlation between polymer Tg and intermolecular interaction. Global and local confinement effects on molecular stiffness during tension. Dynamical heterogeneity behavior on different interactions and temperatures.

Effect of resultant force direction in single point diamond turning of (111)CaF2

On-axis single point diamond turning experiments were performed on (111)CaF2 to investigate the effect of the resulting force system on the single crystal response. The cutting and thrust forces were measured and the resulting surface topography was characterized. The Schmid factors and fracture factors were calculated, and their ratio SfFf*was determined as a function of cutting direction and resultant force angle. It was found that this approach can be used to predict the number and location of resulting fracture lobes on the surface with respect to the lattice orientation. Two regimes with different topography were predicted when turning (111)CaF2, depending on the resultant force angle.

Fundamental Study for Slip Resistance Improvement of High-Strength Bolted Joints Subjected to Shear and Tension

AbstractThe objective of this study was to refine the slip resistance formulas for high-strength bolted joints subjected to combined shear and tension forces. Traditional formulas typically assume that the prying force generated at the contact surface does not contribute to the slip resistance. To explore the influences of the prying force on slip resistance, a trial design was conducted based on the Specifications for Highway Bridges and Recommendation for Design of High Strength Tensile Bolted Connections for Steel Bridges, with variations in parameters such as bolt diameter, bolt pitch, joint flange thickness, and joint flange material. Additionally, numerical analyses were performed to validate the design methodology incorporating prying force. The trial design results demonstrated that the slip capacity improved when the prying force was considered, especially in cases where the external force direction ranged between 27.6 and 90 degrees. The maximum observed improvement in slip capacity was a factor of 1.2. Moreover, the slip resistance of joints with thinner flanges was enhanced when prying force effects were accounted for. This increase in slip capacity due to prying force was further corroborated through fine element method (FEM) simulations. Finally, the findings suggest the potential for enhancing joint compactness and slip resistance.

Quality assessment of spent laying hens and analysis of influencing factors

In China, a considerable number of spent laying hens are disposed annually, with the majority being processed into various food products. The sale of spent laying hens has become a significant revenue stream within the poultry industry. We selected spent laying hens at 100 weeks of age as the research subjects to explore the factors influencing their market price. Information was gathered through product and enterprise investigations. Thereafter, 90 Rhode Island Red laying hens, also at 100 weeks old, were acquired for slaughter. The carcass evaluation was conducted utilizing the methodology prescribed by the United States Department of Agriculture (USDA). Tibial specimens were procured for the purpose of quantifying their length, mass, diameter, maximum breaking strength, maximum breaking distance, as well as for determining the concentrations of calcium, phosphorus, and ash content. Through comprehensive market research and industry surveys, this study found that the primary factor affecting the selling price of spent laying hens is body weight, with 1.5 to 2 kg of chickens being preferred. The USDA quality assessment standards for post-slaughter evaluation, it was found that the incidence of dislocation was 11.1 %, which emerged as a primary factor affecting carcass quality, directly resulting in a decline in quality. The results of the correlation analysis showed that there was no significant relationship between the bone health status and dislocation in laying hens. Dislocations occur mainly due to direct external forces during the culling process caused by the injuries during the slaughter process. Surveys show that the main factor affecting the selling price of spent laying hens is body weight, and the optimal weight range is where farmers gain price advantages during the culling process. The principal factor impacting the carcass quality of spent laying hens is dislocation, which are mainly caused by excessive culling and have no obvious correlation with bone health.

Design and application of a new high-performance flexible six-axis force/torque sensor for massage therapy

Precise sensing of force magnitude and direction in massage therapy can significantly enhance treatment effectiveness. Despite advancements in flexible multidimensional force sensors, achieving comprehensive spatial force sensing with soft materials remains challenging. This study presents a novel flexible six-axis force/torque sensor, calibrated using a deep neural network. The calibrated sensor exhibits a maximum class I error of 0.603%F.S. and a maximum class II error of 0.751%F.S., indicating excellent measurement performance. Demonstrated in massage physiotherapy, the sensor effectively distinguishes between various techniques and accurately detects subtle force variations within the same technique. The present work introduces a novel strategy for designing flexible six-axis force/torque sensors, thereby laying the groundwork for advancements in intelligent robotics, human–computer interfaces, as well as in the fields of rehabilitation and medicine.

Direct forcing immersed boundary method for electro-thermo-buoyant flows in enclosures

This study investigates electro-hydrodynamic (EHD) and electro-thermo-hydrodynamic (ETHD) phenomena in dielectric liquids, and focusses on charge injection as a source of unipolar charges. The studied configuration consists of a hot spherical electrode placed in the center of a cold cubic enclosure, and is numerically simulated using the direct forcing immersed boundary (IB) method. Flow characteristics for both EHD and ETHD flows within this configuration are thoroughly analyzed, both quantitatively and qualitatively, across a representative range of operating parameters. Analyzing ETHD flows results in a more than threefold increase in heat flux from the hot embedded electrode compared to natural convection alone. This study highlights both the similarities and the differences in flow and heat transfer characteristics between the realistic 3D configuration and its 2D counterpart, paving the way for further application of the direct forcing IB method in the analysis of EHD and ETHD flows typical of realistic configurations.

Modified Centroid of Root Projection Method for Determining the Center of Resistance of a Tooth

Abstract Center of resistance (CR) has been widely accepted in dentistry as a reference point for controlling tooth moment, which depends on the direction of loading and the morphology of the periodontal ligament (PDL). In clinical practice, dentists estimate the location of CR based on the morphology of the root of teeth, which may lead to a misestimation of orthodontic treatment. A quick method was proposed to efficiently determine the CR by identifying the centroid of the root projection (CRP), according to the orthodontic force. However, the original CRP method was limited to single-rooted teeth, and it did not provide a strategy for handling the overlapping roots projection of multirooted teeth. To address this issue, we expanded the CRP method to accommodate multirooted teeth by calculating a weighted average of each root’s projection. We further validated the modified CRP method using finite element analysis (FEA) simulation for both single-rooted and multirooted teeth considering mesial–distal and buccal–lingual force directions. The evaluation of displacement distribution along the projection direction allowed us to assess translation and rotation movements, which confirmed that the centroid of root projection can accurately serve as the CR for the multirooted teeth. Additionally, we observed heterogeneous stress distributions in the multirooted teeth. Considering the well-acknowledged bone remodeling effect in response to local stress states, this indicated that comprehensive indexes beyond the CR are desired for evaluating or controlling tooth movement.

Biomechanical analysis of balance control in the elderly By Ba Duan Jin

This study aims to evaluate the biomechanical effects of Ba Duan Jin on balance control in the elderly, seeking effective fitness methods to enhance their balance capabilities and reduce the risk of falls. Methods: Participants were randomly assigned to an experimental group (EG) and a control group (CG), with 25 individuals in each. The Berg Balance Scale (BBS) and mechanical measurements were utilized to evaluate the participants’ balance abilities and biomechanical performance. Statistical analyses were performed to compare the outcomes between the EG and CG, ensuring a comprehensive assessment of the differences. Results: The experimental group demonstrated a significant improvement in the Berg Balance Scale (BBS) scores (p < 0.01), with a notable increase in the eyes-closed standing task (BBS6), which reached significance (p < 0.05), indicating a consistent advantage for the experimental group in this area. Biomechanical measurements revealed that the experimental group exhibited significantly higher parameters compared to the control group, including stability index (EG: 0.7 ± 0.1/2.2 ± 0.4, CG: 0.6 ± 0.1/1.9 ± 0.3), power (EG: 3.2 ± 0.5/3.8 ± 0.6, CG: 2.9 ± 0.4/3.5 ± 0.5), energy expenditure (EG: 20.1 ± 3.8/25.0 ± 4.3, CG: 16.5 ± 3.2/20.3 ± 3.8), and step frequency (EG: 95.0 ± 5.5/105.0 ± 6.0, CG: 85.0 ± 5.0/100.0 ± 5.5). Additionally, peak force (EG: 345.2 ± 30.1/412.6 ± 35.8, CG: 310.4 ± 28.5/310.4 ± 28.5), impact force (EG: 68.3 ± 7.2/85.7 ± 8.9, CG: 55.8 ± 6.7/72.4 ± 8.1), average force (EG: 280.5 ± 25.6/320.7 ± 30.2, CG: 245.3 ± 22.8/280.1 ± 26.4), and direction of force (EG: 10.0 ± 2.0/15.0 ± 2.5, CG: 8.5 ± 1.5/12.0 ± 2.0) also exhibited significant differences (p < 0.05). Notably, the static single-leg stance (EG: 3.38 ± 0.39, CG: 2.38 ± 0.50), dynamic sit-to-stand (EG: 3.77 ± 0.34, CG: 2.85 ± 0.37), turning movements (EG: 3.88 ± 0.27, CG: 2.58 ± 0.56), and double-leg step-ups (EG: 4.00 ± 0.02, CG: 2.69 ± 0.49) displayed extremely significant differences (p < 0.01). These results indicate that Ba Duan Jin training effectively enhances balance control and reduces the risk of falls among the elderly. Conclusion: As a traditional form of physical exercise, Ba Duan Jin effectively enhances balance control and reduces the risk of falls among older adults, providing valuable practical evidence for health management in this population. Future research should focus on conducting more long-term studies with larger sample sizes to verify the applicability and long-term effects of Ba Duan Jin across various age groups and health conditions in older individuals.

Zwitterion-Conjugated Protein Coatings for Enhanced Antifouling in Complex Biofluids: Underlying Molecular Interaction Mechanisms.

Biofouling can cause severe infections, device malfunctions, and failures in diagnostics and therapeutics. Proteins such as bovine serum albumin (BSA) have recently been used as coatings to resist biofouling because they combine surface anchoring and antifouling properties. However, their antifouling effectiveness will significantly deteriorate in complex biofluids with high salinity, limiting their practical applications. In this work, we developed a zwitterion-conjugated protein with enhanced antifouling capability by grafting zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) onto BSA protein via a click reaction. This conjugated protein can easily anchor on various substrates, both inorganic and organic, and exhibits efficient and broad-spectrum fouling resistance to metabolites, proteins, and complex biofluids. Even in the complex fetal bovine serum with higher salinity, the BSA@MPC coating can also maintain 99% fouling resistance robustly, over 6-fold superior to native BSA-coated surfaces in antifouling capability. Direct surface forces measurement reveals that such outstanding antifouling properties of conjugated protein BSA@MPC could be attributed to the stable hydration layer on its surface and the steric repulsion from the antipolyelectrolyte behavior of zwitterionic MPC polymer in the high-salinity environment. Our findings advance the development of protein-based functional materials and provide valuable insights for designing novel antifouling surfaces for marine, food, and bioengineering applications.

Three-dimensional simulation of film boiling on a horizontal surface with magnetic field

This study conducts a numerical investigation into the three-dimensional film boiling of liquid under the influence of external magnetic fields. The numerical method incorporates a sharp phase-change model based on the volume-of-fluid approach to track the liquid–vapour interface. Additionally, a consistent and conservative scheme is employed to calculate the induced current densities and electromagnetic forces. We investigate the magnetohydrodynamic effects on film boiling, particularly examining the pattern transition of the vapour bubble and the evolution of heat transfer characteristics, exposed to either a vertical or horizontal magnetic field. In single-mode scenarios, film boiling under a vertical magnetic field displays an isotropic flow structure, forming a columnar vapour jet at higher magnetic field intensities. In contrast, horizontal magnetic fields result in anisotropic flow, creating a two-dimensional vapour sheet as the magnetic strength increases. In multi-mode scenarios, the patterns observed in single-mode film boiling persist, with the interaction of vapour bubbles introducing additional complexity to the magnetohydrodynamic flow. More importantly, our comprehensive analysis reveals how and why distinct boiling effects are generated by various orientations of magnetic fields, which induce directional electromagnetic forces to suppress flow vortices within the cross-sectional plane.

Asymmetric and Ultrasensitive Structural Color Response in Nanochain‐Embedded Photonic Composites

AbstractMechanochromic photonic crystals, capable of altering structural colors in response to external forces, are emerging intelligent materials in various fields, such as visual sensors and anti‐counterfeiting technologies. However, conventional mechanical responses of photonic crystals mainly rely on stretching or compression, resulting in symmetric and limited mechanochromic effects due to restricted changes in lattice spacing, particularly limiting the recognition of the direction of force. Here, asymmetric and ultrasensitive structural color responses are reported in colloidal photonic composites featuring embedded one‐dimensional (1D) photonic nanochains of colloidal particles based on shear‐induced lattice orientation change. It is shown that shearing deformation tilts the photonic nanochains within the polymer matrix, leading to a remarkable and asymmetric color shift depending on shear force and observing directions. The asymmetric response encourages to develop ultrasensitive twist sensors capable of detecting subtle twisting movements as low as 0.2° and twist direction. Furthermore, by integrating magnetic and deformation orientation control, dynamic optical anti‐counterfeiting labels capable of displaying highly intricate patterns are devised. This unique shear‐induced color‐shifting mechanism expands the responsiveness of mechanochromic materials, with broad implications in many other areas, including structural health monitoring, soft robotics, and artificial skin.

Light‐Manipulated Millimeter‐Scale Swimming Robot for Precise Navigation

AbstractMicro‐swimming robots have been increasingly emphasized in the fields of targeted drug delivery and water surface cleaning, which mainly use open external structures or external environments to assist navigation, but there are still salient problems, such as the difficulty of stable capture and poor navigation accuracy. Theoretically, a light‐driven swimming robot can have a symmetrical embedded structure to constrain surface tension gradient forces and thermophoretic forces in a wide range of directions and convert them into precise directional forces. Therefore, a sustained‐capture swimming robot is developed with precise navigation consisting of TiO2/polypyrrole (PPy) composites containing a symmetric inner truncated‐cone hole structure and realized multiple controllable motion patterns. Excitingly, the capture motion of the TiO2/PPy inner truncated‐cone hole structure robot “TPHR” can be accurately controlled by programmable automation, with capture travel speeds of up to ≈23.64 mm s−1. Its excellent kinematic performance stems from the high photothermal conversion efficiency (≈47.83%) of the composite and the synergistic effect between thermo‐capillary and thermo‐convective flows. Furthermore, a patterning precision movement, water surface oil‐cleaning microstructure assembly, etc. are realized, reflecting the engineering application value of TPHR. This structure provides a novel strategy for the development of micro‐swimming robots with stable capture and sustainable motion.

Minimalist Design for Multi-Dimensional Pressure-Sensing and Feedback Glove with Variable Perception Communication

Immersive human–machine interaction relies on comprehensive sensing and feedback systems, which enable transmission of multiple pieces of information. However, the integration of increasing numbers of feedback actuators and sensors causes a severe issue in terms of system complexity. In this work, we propose a pressure-sensing and feedback glove that enables multi-dimensional pressure sensing and feedback with a minimalist design of the functional units. The proposed glove consists of modular strain and pressure sensors based on films of liquid metal microchannels and coin vibrators. Strain sensors located at the finger joints can simultaneously project the bending motion of the individual joint into the virtual space or robotic hand. For subsequent tactile interactions, the design of two symmetrically distributed pressure sensors and vibrators at the fingertips possesses capabilities for multi-directional pressure sensing and feedback by evaluating the relationship of the signal variations between two sensors and tuning the feedback intensities of two vibrators. Consequently, both dynamic and static multi-dimensional pressure communication can be realized, and the vibrational actuation can be monitored by a liquid-metal-based sensor via a triboelectric sensing mechanism. A demonstration of object interaction indicates that the proposed glove can effectively detect dynamic force in varied directions at the fingertip while offering the reconstruction of a similar perception via the haptic feedback function. This device introduces an approach that adopts a minimalist design to achieve a multi-functional system, and it can benefit commercial applications in a more cost-effective way.

Effect of different corrective force directions applied by spinal orthoses on the patients with adolescent idiopathic scoliosis

BackgroundSpinal orthoses are commonly prescribed for adolescent idiopathic scoliosis (AIS), yet their three-dimensional correction was not fully understood. The amount of deformity control largely depends on the corrective forces applied, which remain empirically based due to a lack of consensus on optimal force application. This study investigated the effects of different corrective force directions exerted by spinal orthoses on patients with AIS.MethodsA retrospective analysis was conducted on 78 subjects. The trunk was segmented into four quadrants using coronal and sagittal planes from a top-down perspective. Each left or right posterolateral quadrant (with 90°) was further subdivided into zones 1–4, from the sagittal to coronal planes. Based on the zone where the resultant corrective force direction fell, the subjects were categorized into Group 1 (zone 1), Group 2 (zone 2), Group 3 (zone 3), or Group 4 (zone 4). The direction of the corrective force was estimated using modified models of the subjects’ bodies, designed through a computer-aided design and manufacturing system integral to the orthosis fabrication process. The effects of corrective forces in different zones on scoliotic spine were assessed.ResultsAmong the subjects, 3 were in Group 1, 17 in Group 2, 52 in Group 3, and 6 in Group 4. Due to the limited number of subjects, data from Groups 1 and 4 were not analysed. Groups 2 and 3 showed significant reductions in Cobb angle in the coronal plane and plane of maximum curvature (PMC) following orthosis fitting (p < 0.05). Group 2 displayed a significant decrease > 5º in thoracic kyphosis (p < 0.05). Both Groups 2 and 3 exhibited significant reductions in lumbar lordosis. PMC orientation remained unchanged over time (p > 0.05) but was notably higher in Group 2 after orthosis fitting (p < 0.05).ConclusionsCorrective forces applied by spinal orthoses in zones 2 and 3 effectively controlled lateral curve progression. Notably, only forces in zone 3 neither significantly reduced thoracic kyphosis nor exacerbated the deviation of scoliotic spine from the sagittal plane. Further research is needed to validate and expand upon these results.

Precision Orthodontic Force Simulation Using Nodal Displacement-Based Archwire Loading Approach.

Precision in force simulationis critical for forecasting tooth movement and optimizing orthodontic treatment strategies. While traditional techniques have provided valuable insights, there remains a need for improved methodologies that can seamlessly integrate with fixed orthodontic practices. This study aims to refine orthodontic force simulation techniques by integrating a nodal displacement approach within finite element analysis, specifically designed to enhance prediction accuracy in tooth movement and optimize orthodontic treatment planning. Three-dimensional patient-specific models of the Tooth, Periodontal Ligament, and Bone Complex (TPBC) of five volunteers were created, along with models of brackets and wires. The simulation involved an initial step of estimating node displacements to align the archwire with the brackets, followed by a subsequent step to attain the required tooth movement and determine the orthodontic force. Experimental validation of the simulation results was performed using an orthodontic force tester (OFT). Utilizing the nodal displacement approach, the simulation successfully positioned the archwire onto the brackets. When benchmarked against the OFT, 80% of the simulated force directions exhibited angular discrepancies of less than 5°. Additionally, the absolute differences in force magnitude reached 20.06 cN, and in moments, up to 71.76 cN mm. The relative differences were as high as 9.55% for force and 13.83% for moments. These findings represent an improvement of up to 10.45% in force accuracy and 8.87% in moment accuracy compared to median values reported in most recent literature. In this research, a nodal displacement methodology was employed to simulate orthodontic forces with precision across the dental arch. The results demonstrate the approache's potential to enhance the accuracy of force prediction in orthodontic treatment planning, thereby advancing our understanding of orthodontic biomechanics.