Traction Force Research Articles

Effect of force direction and impaction angulation during dilaceration impacted central incisor traction: a finite element analysis

BackgroundThe effects of traction forces at different angles on impacted central incisors(ICI)with varying inverted angles (IA) may be different. The objective of this study was to analyze the biomechanical effects of different force directions (FD) on developmentally inverted ICI with multi-angle variations and to offer insights and guidance for the treatment of inverted ICI.MethodsThree-dimensional finite element method was employed to simulate clinical scenarios of inverted ICI traction. As such, 0.2 N of force (direction: antero-superior angles of 90°, 100°, 110°, 120°, and 130° relative to the long axis of the inverted ICI crown) was applied to the inverted ICI with inverse angles (IA) of 40°, 30°, 20°, 10° and 0°. Inverted ICI apical displacement and Von Mises stress on periodontal ligament (PDL) and alveolar bone were compared.ResultsIA and FD showed minimal influence on the stress distribution in the PDL, as higher stresses were concentrated in the apical region. The higher stresses in the alveolar bone are focused on the cervical and apical regions of the tooth. In particular, IA exerts a more significant impact on stress distribution in the alveolar bone than FD. The influence of IA on the apical displacement of inverted ICI is larger than that of FD.ConclusionsTo promote the health of the root and periodontal tissues, it is recommended to use an angle of 100°-110° relative to the long axis of the ICI crown when dealing with a large IA (> 20°) developmentally inverted ICI. Conversely, an angle of 110°-120° can be used.

Traction Force, Sowing Quality, and Deformation Characteristics of the Coulter of a Grain–Fertilizer–Grass Seeder

The development of restoration technology and meadows, improvement of run-down pastures, and productivity improvement of old crops of perennial grasses is an urgent problem in agriculture. The tillage traction force in seeder designing and manufacturing is an important indicator of energy efficiency. The objective of this work is to reduce traction force and ensure seeding depth uniformity by justifying the optimal chisel parameters of a grain–fertilizer–grass seeder for direct seeding in sod. The Box–Behnken method was applied to investigate the traction force dependence on the seeder velocity, seed embedding depth, chisel width, and mounting angle. The obtained optimal parameters of coulters were justified by the finite element method. Structural and technological parameters were checked using the smoothed-particle hydrodynamics method on the deformation and wear of the seeder working body. The revealed optimal coulter parameters were as follows: chisel width was 20–20.97 mm, chisel length was 145–148.9 mm, mounting angle was 75°–81.6°, and achieved minimum traction force was 720 N. These parameters ensure the quality of grass seed embedding in the sod. The theoretical data of traction force (8.27–8.39 kN) are in accordance with the experimental (8.28–8.63 kN) data under field conditions. These findings are efficient in agrotechnical and mechanical predictions regarding the occurrence of chisel residual stresses and the working lifetime of the part.

Inferring cellular contractile forces and work using deep morphology traction microscopy

Traction-force microscopy (TFM) has emerged as a widely used standard methodology to measure cell-generated traction forces and determine their role in regulating cell behavior. While TFM platforms have enabled many discoveries, their implementation remains limited due to complex experimental procedures, specialized substrates, and the ill-posed inverse problem whereby low-magnitude high-frequency noise in the displacement field severely contaminates the resulting traction measurements. Here, we introduce deep morphology traction microscopy (DeepMorphoTM), a deep-learning alternative to conventional TFM approaches. DeepMorphoTM first infers cell-induced substrate displacement solely from a sequence of cell shapes and subsequently computes cellular traction forces, thus avoiding the requirement of a specialized fiduciarily marked deformable substrate or force-free reference image. Rather, this technique drastically simplifies the overall experimental methodology, imaging, and analysis needed to conduct cell-contractility measurements. We demonstrate that DeepMorphoTM quantitatively matches conventional TFM results while offering stability against the biological variability in cell contractility for a given cell shape. Without high-frequency noise in the inferred displacement, DeepMorphoTM also resolves the ill-posedness of traction computation, increasing the consistency and accuracy of traction analysis. We demonstrate the accurate extrapolation across several cell types and substrate materials, suggesting robustness of the methodology. Accordingly, we present DeepMorphoTM as a capable yet simpler alternative to conventional TFM for characterizing cellular contractility in two dimensions.

MiR-29a-3p orchestrates key signaling pathways for enhanced migration of human mesenchymal stem cells

BackgroundThe homing of human mesenchymal stem cells (hMSCs) is crucial for their therapeutic efficacy and is characterized by the orchestrated regulation of multiple signaling modules. However, the principal upstream regulators that synchronize these signaling pathways and their mechanisms during cellular migration remain largely unexplored.MethodsmiR-29a-3p was exogenously expressed in either wild-type or DiGeorge syndrome critical region 8 (DGCR8) knockdown hMSCs. Multiple pathway components were analyzed using Western blotting, immunohistochemistry, and real-time quantitative PCR. hMSC migration was assessed both in vitro and in vivo through wound healing, Transwell, contraction, and in vivo migration assays. Extensive bioinformatic analyses using gene set enrichment analysis and Ingenuity pathway analysis identified enriched pathways, upstream regulators, and downstream targets.ResultsThe global depletion of microRNAs (miRNAs) due to DGCR8 gene silencing, a critical component of miRNA biogenesis, significantly impaired hMSC migration. The bioinformatics analysis identified miR-29a-3p as a pivotal upstream regulator. Its overexpression in DGCR8-knockdown hMSCs markedly improved their migration capabilities. Our data demonstrate that miR-29a-3p enhances cell migration by directly inhibiting two key phosphatases: protein tyrosine phosphatase receptor type kappa (PTPRK) and phosphatase and tensin homolog (PTEN). The ectopic expression of miR-29a-3p stabilized the polarization of the Golgi apparatus and actin cytoskeleton during wound healing. It also altered actomyosin contractility and cellular traction forces by changing the distribution and phosphorylation of myosin light chain 2. Additionally, it regulated focal adhesions by modulating the levels of PTPRK and paxillin. In immunocompromised mice, the migration of hMSCs overexpressing miR-29a-3p toward a chemoattractant significantly increased.ConclusionsOur findings identify miR-29a-3p as a key upstream regulator that governs hMSC migration. Specifically, it was found to modulate principal signaling pathways, including polarization, actin cytoskeleton, contractility, and adhesion, both in vitro and in vivo, thereby reinforcing migration regulatory circuits.

Uncertainty-Aware Traction Force Microscopy.

Traction Force Microscopy (TFM) is a versatile tool to quantify cell-exerted forces by imaging and tracking fiduciary markers embedded in elastic substrates. The computations involved in TFM are ill-conditioned, and data smoothing or regularization is required to avoid overfitting the noise in the tracked substrate displacements. Most TFM calculations depend critically on the heuristic selection of regularization (hyper)parameters affecting the balance between overfitting and smoothing. However, TFM methods rarely estimate or account for measurement errors in substrate deformation to adjust the regularization level accordingly. Moreover, there is a lack of tools to quantify how these errors propagate to the recovered traction stresses. These limitations make it difficult to interpret TFM readouts and hinder comparing different experiments. This manuscript presents an uncertainty-aware TFM technique that estimates the variability in the magnitude and direction of the traction stress vector recovered at each point in space and time of each experiment. In this technique, substrate deformation and its uncertainty are quantified using a non-parametric bootstrap PIV method by resampling the microscopy image pixels (PIV-UQ). This information is passed to a hierarchical Bayesian framework that automatically selects its hyperparameters to perform spatially adaptive regularization conditioned on image quality and propagates the uncertainty to the traction stress readouts (TFM-UQ). We validate the performance of PIV-UQ and TFM-UQ using synthetic datasets with prescribed image quality variations and demonstrate the application of PIV-UQ and TFM-UQ to experimental datasets. These studies show that TFM-UQ locally adapts the level of smoothing, outperforming traditional regularization methods. They also illustrate how uncertainty-aware TFM tools can be used to objectively choose key image analysis parameters like PIV-UQ interrogation window size. We anticipate that these tools will allow for decoupling biological heterogeneity from measurement variability and facilitate automating the analysis of large datasets by parameter-free, input data-based regularization.

Dynamic nanomechanical characterization of cells in exosome therapy

Exosomes derived from mesenchymal stem cells (MSCs) have been confirmed to enhance cell proliferation and improve tissue repair. Exosomes release their contents into the cytoplasmic solution of the recipient cell to mediate cell expression, which is the main pathway through which exosomes exert therapeutic effects. The corresponding process of exosome internalization mainly occurs in the early stage of treatment. However, the therapeutic effect of exosomes in the early stage remains to be further studied. We report that the three-dimensional cell traction force can intuitively reflect the ability of exosomes to enhance the cytoskeleton and cell contractility of recipient cells, serving as an effective method to characterize the therapeutic effect of exosomes. Compared with traditional biochemical methods, we can visualize the early therapeutic effect of exosomes in real time without damage by quantifying the cell traction force. Through quantitative analysis of traction forces, we found that endometrial stromal cells exhibit short-term cell roundness accompanied by greater traction force during the early stage of exosome therapy. Further experiments revealed that exosomes enhance the traction force and cytoskeleton by regulating the Rac1/RhoA signaling pathway, thereby promoting cell proliferation. This work provides an effective method for rapidly quantifying the therapeutic effects of exosomes and studying the underlying mechanisms involved.

Дослідження режимів розгону автомобіля Skoda Octavia на роликовому стенді

As you know, the main characteristics that determine the state of the power unit are the power level and torque. These parameters affect the dynamic qualities of the car and can also play a role in fuel consumption and emission levels. To check these characteristics, traction roller stands of the inertial type are used. These stands allow you to simulate real traffic conditions and loads. Usually, on such stands, the traction force on the driving wheels is measured, which makes it easy to calculate the power in certain driving modes. However, creating a full-fledged load on the driving wheels of the car being diagnosed requires the use of powerful loading and driving devices. This significantly increases the cost of the stand and its metal content. An alternative to this method is the compressed acceleration method. In this method, the load is created by a relatively small inertial mass together with a loading and driving device of moderate power. The diagnostic parameter in this method can be traction force on the wheels, acceleration, time or path of acceleration of the wheels in the selected speed range. For measurement accuracy, it is better to use acceleration time. However, all the advantages of the method can be manifested only with the correct choice of test modes. During testing, results depend on the accuracy and stability of maintaining the test mode. Acceleration time will be measured more accurately, the slower the wheels and rollers of the stand accelerate. During the tests, it is necessary to choose the high-speed measurement mode to ensure a sufficiently stable torque value. The article analyzes the acceleration modes of a car on a roller stand and their influence on the accuracy of diagnostics. The smallest error is achieved when measuring acceleration time from 50 to 70 km/h in IV gear with additional load or in V gear without load.

Аналіз впливу на прохідність автобронетанкової техніки конструктивних факторів та методика її збільшення шляхом автоматичного регулювання тиску повітря в шинах коліс

The purpose of the study is to analyze and determine the influence of various factors on the patency of armored vehicles (AMT) operated by the National Guard of Ukraine. Determination of the change in patency during the movement of AMT in different road and climatic conditions. Analysis of static and dynamic loads, which are characteristic of AMT movement over rough terrain, and their impact on the efficiency of the vehicle. The theoretical component of the study was carried out using mathematical modeling of the work process of regulating the air pressure in tires of AMT wheels, using the example of changes in the characteristics of adhesion coefficients with the supporting surface and rolling resistance depending on the change in pressure and load on the tires of the wheels when the AMT is moving off-road. As a result of mathematical modeling, the dependences of air pressure in tires of AMT wheels were obtained, depending on the coefficient of rolling resistance and the load on each of the wheels. Which, in turn, makes it possible to move to a sufficiently complete mathematical modeling of the movement of AMT on off-road, taking into account the reference cross-country ability. In the process of theoretical research, the structural parameters of the impact on the patency of AMT were analyzed quite completely, and a generalized comparative indicator of the patency parameters of vehicles was proposed. When analyzing it, it was found that the AMT tire and, specifically, the change in air pressure in it, have a significant impact on the bearing capacity. The authors propose to use the following evaluation criteria as criteria for assessing the efficiency of the passability when driving on deformable surfaces: a generalized comparative indicator of the parameters of the passability of vehicles. As a result of consideration of which, a significant influence on the patency parameters of the tires and directly the air pressure in them was established. Regulation and change of the air pressure in the tires of the wheels depending on the change in the coefficient of rolling resistance as well as the change in the load on each wheel, which are the ratio of the work that is spent on the traction force when overcoming different degrees of heaviness of the resistance of the supporting surfaces with the effect of deformation. And the load that falls on each of the AMT wheels allowed us to draw conclusions about the improvement of the regular tire pressure regulation system (RPRS) of the wheels.

Вплив причіпних ланок на керованість тракторних самохідних шасі

An analysis of methods for calculating the distribution of normal reactions of the road between the axles of the tractor unit was carried out. It is shown that they are based on the misconception that traction forces and rolling resistance forces are applied in the spots of contact of the wheels with the road. The research shows that installing a towing link on a tractor self-propelled chassis through the rear suspension system at a level below the axis of the rear wheels (the diameter of which is larger in relation to the diameter of the front wheels) allows reducing the additional unloading of the front wheels. A more correct scheme of the tractor unit with the application of the traction force and the rolling resistance force on the wheel axles is calculated, which determines the increase in the total normal reaction on the front wheels of the tractor self-propelled chassis when working with the towing link. It is shown that an increase in the difference in the dynamic radii of the front and rear wheels, a decrease in the vertical coordinate of the center of mass of the tractor unit leads to an increase in the normal reaction of the road on the front wheels. Since the controllability of wheeled machines increases with the growth of the normal reaction on the front wheels, the presence of towing links with the attachment point located below the axis of the rear driving wheel increases the controllability of the tractor unit based on the self-propelled chassis. The problem of determining the total normal reaction of the road on the front wheels of a tractor self-propelled chassis with a trailing link in the case of application of the traction force and the force of movement resistance on the wheel axles has been solved. To increase the accuracy of finding the total normal reaction of the road on the front wheels of the tractor self-propelled chassis, which will allow to clarify the assessment of the controllability of the latter when moving with a towed link. Increasing the difference in the dynamic radii of the wheels and reducing the base of the tractor self-propelled chassis allows you to increase the value of the total normal reaction of the road on the wheels in relation to the horizontal reaction in the hinge of the axle of the trailer link. It was determined that the operation of the tractor self-propelled chassis with trailing links is characterized by a higher efficiency factor of its chassis compared to a universal tractor of class 0.6 and higher efforts under the condition that its front platform is loaded.

Режими роботи маніпулятора ремонтно-евакуаційної машини

With modern methods of conducting military operations, the system of technical support of the troops is of great importance. One of the ways to increase the effectiveness of the system of technical support of troops is the use of armored repair and evacuation vehicles. It is possible to increase the technical capabilities of armored repair and evacuation vehicles by modernizing existing models, or creating qualitatively new vehicles that take into account the specifics of use and characteristic combat damage of modern weapons and military equipment, the type of engine of the military vehicle, its weight and dimensions and other characteristics. Improvement and modernization of armored repair and evacuation vehicles allows to ensure their effectiveness. Armored repair and evacuation vehicles demonstrate high efficiency when carrying out operations to extract or lift damaged or stuck, blocked, bogged down, sunken military equipment. In these cases, the traction force of the armored recovery vehicle's own engine is used or its own specialized means of evacuation: crane winches, polyspatch systems, crane booms together with power hydraulic cylinders of their drive, levers, other evacuation equipment. Features of the lifting and loading equipment include such modes of operation as lifting loads from a solid surface, detaching the load from a viscous surface, dragging at different angles to the support surface, and getting stuck. The most difficult in terms of dynamic overloads of all elements of the hydraulic manipulator is the mode of partial immersion and dense sticking of the load in clay soil, when after separation from it, the load under the action of the forces of elastic deformations of the suspension flies up to the height of a significant relaxation of the suspension and reaching the upper point, where its speed is zero, falls down on an elastic suspension. At the same time, a three-fold overload of the manipulator links is observed.

Evaluation of artificial neurocomputing algorithms and their metacognitive robustness in predictive modeling of fuel consumption rates during tillage

Artificial intelligence (AI) requires complex neurocomputing algorithms (NCAs) for robustness in predictive modeling. Since 1990, a plethora of NCAs have evolved, challenging selection of the most intelligent and error-tolerant model for predicting fuel consumption rate (ØFuel) in tillage. This study adopted 12 recent NCAs in modeling 72 neurocomputing architectures and evaluated their metacognitive robustness in predicting ØFuel using 80 tillage datasets. These included Levenberg-Marquardt (trainlm), Quasi-newton (trainbfg), Powell-Beale conjugate gradient (traincgb), Scaled conjugate gradient (trainscg), Fletcher-reeves conjugate gradient (traincgf), Polak-ribiére conjugate gradient (traincgp), Onestep secant (trainoss), Bayesian regularization (trainbr), Resilient backpropagation (trainrp), Gradient descent (traingd), Learning rate gradient descent (traingdx) and Gradient descent momentum (traingdm). Tillage variables were sequentially subjected to NCA architectures learning on logsig, Purelin, and tansig neuro-activation functions, targeting 1000 epochs. Neuro-cognitive performance was evaluated through broad multi-criteria of regressed neuron input–output functions using heuristic and accuracy metrics, i.e., training time (t), number of hidden layers (NL), and neurons (Nn), optimal epoch (Eopt), Coefficient of correlation (R) and determination (R2), Mean square error (MSE), Root mean square error (RMSE), Mean absolute error (MAE), Mean absolute percentage error (MAPE), Sum square error (SSE), Prediction scatter (Tscatter), Coefficient of variation (CV) and Prediction accuracy (PA). Prediction reliability and robustness were evaluated using a20-index (a20), Willmott’s index of agreement (IOA), Index of scatter (IOS), Variance accounted for (VAF), Performance index (PI), Total score rank (ξtotal), Sensitivity index (SAij) and Anderson-Darling (AD) test. Results indicated that varying NL and Nn did not correspond with t, Eopt and PA but only occurred in single-layered trainbr and double-layered trainlm. Although PA increased at reduced convergence error limits, relationships among Eopt, t, and PA were unclear. Single-layered trainbr (14-20-1) outperformed all NCAs with R (0.9993), R2 (0.9986), MSE (6.34e-06), RMSE (0.0025), MAE (0.003), MAPE (1.4e-06), SSE (8e-04), R2All (0.9998) Tvalue (1.0), CV (3.232 %) and PA (99.81 %). However, trainlm (14-20-10-1) most accurately modeled double-layered architectures i.e. R (0.9932), R2 (0.9864), MSE (7.4e-05), RMSE (0.009), MAE (0.004), MAPE (0.003), SSE (0.003), R2All (0.9929), Tvalue (0.9998), CV (3.212 %) and PA (97.8 %). Nonetheless, trainbr (14-20-1) achieved the best reliability metrics of a20 (100 %), VAF (99.98 %), IOA (1.00), PI (1.9971), IOS (0.0115), ξtotal (284) and AD-test (2.6852). Sensitivity analysis revealed that tractive force had the most significant influence on ØFuel while tire inflation pressure had the least. Learning on transig neuro-activation function in single-layered neural network, metacognitive robustness of trainbr is superiorly merited for predicting ØFuel during tillage.

Quantitative atlas of collagen hydrogels reveals mesenchymal cancer cell traction adaptation to the matrix nanoarchitecture

Collagen-based hydrogels are commonly used in mechanobiology to mimic the extracellular matrix. A quantitative analysis of the influence of collagen concentration and properties on the structure and mechanics of the hydrogels is essential for tailored design adjustments for specific in vitro conditions. We combined focused ion beam scanning electron microscopy and rheology to provide a detailed quantitative atlas of the mechanical and nanoscale three-dimensional structural alterations that occur when manipulating different hydrogel's physicochemistry. Moreover, we study the effects of such alterations on the phenotype of breast cancer cells and their mechanical interactions with the extracellular matrix. Regardless of the microenvironment's pore size, porosity or mechanical properties, cancer cells are able to reach a stable mesenchymal-like morphology. Additionally, employing 3D traction force microscopy, a positive correlation between cellular tractions and ECM mechanics is observed up to a critical threshold, beyond which tractions plateau. This suggests that cancer cells in a stable mesenchymal state calibrate their mechanical interactions with the ECM to keep their migration and invasiveness capacities unaltered. Statement of significanceThe paper presents a thorough study on the mechanical microenvironment in breast cancer cells during their interaction with collagen based hydrogels of different compositions. The hydrogels’ microstructure were obtained using state-of-the-art 3D microscopy, namely focused ion beam-scanning electron microscope (FIB-SEM). FIB-SEM was originally applied in this work to reconstruct complex fibered collagen microstructures within the nanometer range, to obtain key microarchitectural parameters. The mechanical microenvironment of cells was recovered using Traction Force Microscopy (TFM). The obtained results suggest that cells calibrate tractions such that they depend on mechanical, microstructural and physicochemical characteristics of the hydrogels, hence revealing a steric hindrance. We hypothesize that cancer cells studied in this paper tune their mechanical state to keep their migration and invasiveness capacities unaltered.

Relationship between Pelvic Dimensions and Maximum Traction Forces Required during Parturition in Holstein Cows Using a Biomechanical Obstetric Simulator.

The primary aim of this study was to investigate the effect of the pelvic dimensions of Holstein cows on the traction forces during parturition. Additionally, the relationship between calf measurements and traction forces was explored. For this purpose, a modified in vitro biomechanical model simulating obstetric tractions was used. For the requirements of the experiment, six bone pelvises of deceased Holstein cows were collected based on their estimated pelvic inlet area (EPA) and prepared. Additionally, six stillborn calves were collected based on their body weight (BW). The parameters of the pelvic inlet and cavity were measured using computed tomography (CT). Using the simulator, every calf was pulled in a random order through all pelvises, realizing a total of 36 obstetrical tractions, and the required forces were documented with appropriate software. In each extraction, three peaks of forces were recorded, with the first peak occurring at the entrance of the elbows into the maternal pelvic cavity, the second peak at the entrance of the thorax, and the third at the entrance of the calf's pelvis. Logistic regression revealed an exponential relationship between pelvic parameters and traction forces for the entrance of the elbows and the pelvis, with the recorded forces being higher in the two smallest pelvises and stabilizing at a lower level thereafter, while for the entrance of the thorax, the correlations were either exponential or linear. The adjusted coefficients of determination (r2) were generally above the threshold of 0.5 for the entrance of the elbows and pelvis and lower (0.3-0.4) regarding the thorax and were statistically significant (p < 0.05) in all cases. Regarding the relationships between the calf dimensions and the required traction forces, the types of correlations were primarily linear and of lower magnitude. The combination of pelvic and calf parameters in a multivariate model resulted in an r2 of 0.72 for the entrance of the elbows using the pelvic diagonal and calf's body weight, an r2 of 0.62 using the pelvic area and calf's thoracic circumference, and an r2 of 0.75 using the pelvic diagonal and calf's fetlock joint width. In conclusion, under the conditions of the present experimentation, the applied traction forces were mainly influenced by the pelvic dimensions in an exponential manner, whereas the calf body measurements showed a weaker effect. Based on these findings, critical cut-off points exist, different for every pelvic parameter, below which a significant increase in the required traction forces is expected.

Design and multi-body dynamic analysis of inline and offset track configuration in deep-sea mining vehicles for enhanced traction in soft seabed

The deep sea polymetallic nodule mining vehicle maneuverability depends on the vehicle track parameters and track configuration. The traction force offered by the deep sea soil is very limited for the mining vehicle during dynamic operating conditions on the seabed and it is very critical to maneuver against the external resistances. The present study strives to arrive at optimum track parameters for enhancing the traction of the vehicle for the pre-determined seabed conditions. The efficacy of the four tracks in Inline and Offset track configurations on the soft soil has been compared. To improve the traction force estimation, the existing mathematical model was modified with the inclusion of dynamic variation of shear stress-shear displacement characteristics and variation in shear residual displacement concerning the track parameters. The modified mathematical model was solved in a well-established mathematical tool and found that there are 30 percent improvements in the traction force generation for the offset configuration over inline track configuration. The optimum track length to width ratio (L/b) was also estimated for the given contact area to configure the vehicle track for improvement of the traction. Further, a Multi-Body Dynamic (MBD) analysis has been carried out in commercially available soil-machine interaction tool for the inline and offset track configurations with actual measured seabed soil parameters. The MBD analysis proved that the sinkage and vehicle gradient is significantly increased in the inline track configuration due to disturbance created by the front tracks. The simulation results confirm that the offset track configuration is suitable for the deep sea soil conditions for handling the higher payload of a deep sea mining vehicle.

The characterization of cell traction force on nonflat surfaces with different curvature by elastic hydrogel microspheres.

It is of great importance to study the detachment/attachment behaviors of cells (cancer cell, immune cell, and epithelial cell), as they are closely related with tumor metastasis, immunoreaction, and tissue development at variety scales. To characterize the detachment/attachment during the interaction between cells and substrate, some researchers proposed using cell traction force (CTF) as the indicator. To date, various strategies have been developed to measure the CTF. However, these methods only realize the measurements of cell passive forces on flat cases. To quantify the active CTF on nonflat surfaces, which can better mimic the in vivo case, we employed elastic hydrogel microspheres as a force sensor. The microspheres were fabricated by microfluidic chips with controllable size and mechanical properties to mimic substrate. Cells were cultured on microsphere and the CTF led to the deformation of microsphere. By detecting the morphology information, the CTF exerted by attached cells can be calculated by the in-house numerical code. Using these microspheres, the CTF of various cells (including tumor cell, immunological cell, and epithelium cell) were successfully obtained on nonflat surfaces with different curvature radii. The proposed method provides a versatile platform to measure the CTF with high precision and to understand the detachment/attachment behaviors during physiology processes.

The effect of cervical traction on stabilometric parameters in cervical radiculopathy patients: A randomized crossover study.

Cervical traction is effective on pain and function in patients with cervical radiculopathy but its effectiveness on balance disorders has not yet been studied. To evaluate the effect of mechanical intermittent cervical traction (MICT) on stabilometric parameters in patients with cervical radiculopathy. This randomized crossover study assigned 20patients with cervical radiculopathy to one of the two groups: Group effective traction (ET)/sham traction (ST) (n= 10) treated firstly with ET (traction force of 12Kg) then with ST (traction force of 2Kg) with one-week interval and group ST/ET (n= 10) treated invertedly with a ST then ET. Each traction procedure was maintained for 10minutes twice separated by 5minutes of rest. Patients were assessed before and immediately after MICT procedure. Main outcome measures were stabilometric parameters: center of pressure, sway area and lateral and anteroposterior displacements using a force platform. Secondary outcome measures were pain intensity, grip strength and dizziness. ET has provided a significantly greater improvement in both groups and in the total population in terms of stabilometric parameters (p< 0.01), pain intensity, and grip strength (p< 0.05), compared to ST. MICT seems to have an immediate beneficial effect on stabilometric parameters, pain and grip strength in patients with cervical radiculopathy.

Design for Copying Grouser and Bionic Convex Hull Patterns on Track Surfaces of Crawler Combine Harvesters

In the rainy season, which often has uncertain rainfall, crawler combine harvesters have difficulty traversing wet and soft rice fields. A large amount of clay is often accumulated on the track surfaces, resulting in frequent slipping and sinking, which greatly affects the operational performance and harvesting efficiency of crawler combine harvesters. To address this issue, this paper proposes a high-traction track grouser based on the structure of an ostrich’s foot sole. First, a traction force mathematical model is constructed to analyze the interaction between a track grouser and wet and soft rice fields, and parameter optimization is conducted. Then, the bionic information of a dung beetle’s non-smooth body surface is extracted, and the surface of the track is designed with biomimetic convex hull patterns based on the geometric similarity principle and adhesive experiments. Finally, the analysis results indicate that the optimized track grouser significantly improved the traction of the track in wet and soft rice fields. For the track plate with a bionic desorption convex hull pattern, a convex hull diameter of 6 mm, convex hull spacing of 8.25 mm, and convex hull height of 3 mm led to good adhesion reduction and desorption effects in wet and soft soil.

O-229 Neck scarf of ureter and Intraoperative ICG-fluorescence for preventing ureters injuries in Da Vinci Robotic deep infiltrating endometriosis excision

Abstract Study question To prevent ureters injury during deep infiltrating endometriosis excision. Summary answer Identify the ureter course with ICG and near-infrared fluorescence (NIRF) imaging mode and traction with a vessel loop like neck scarf in white light mode. What is known already Deep infiltrating endometriosis is one of the most challenging gynecologic operation due to the distorted anatomy by the fibrosis of endometriosis gland.Identification of ureters through intraurethral ICG instillation and NIRF imaging has been reported to be useful during robotic surgery. However, surgeons cannot do robotic ureterolysis in Firefly NIRF imaging mode. When shift back to the white light mode, surgeons could only try to remember the ureter course during the ureterolysis procedure.When the ureter course was in doubt, the surgeon must shift back to the ICG-NIRF image mode again. Study design, size, duration From 2017 Jan1 till 2024 Jan 7, a single surgeon perform 47 consecutive patients with DIE received robotic surgery with ureterolysis from pelvic brim to the level of uterine vessels crossing them. Yellow and blue rubber bands were used to collar the ureters as a neck scarf, with Da Vinci robot system (SI, XI)The third arm as an stable assistant to traction the neck scarf to traction ureter indirectly in different direction when ureterolysis. Participants/materials, setting, methods We perform cystoscopy and intraurethral ICG injection with or without ureteral stent placement and Inject ICG-fluorescence with Firefly fluorescence imaging if the ureters were hard to find due to adhesion and fibrosis. Under the Firefly NIRF imaging mode,the location of ureter over the pelvic brim was found and the vessel loops were set up. Then shift back to white light mode to do the ureterolysis. Main results and the role of chance 47 consecutive patients with deep infiltrating endometriosis were safely operated without fistula, ureter injury, laceration during one month to 5 years period follow up. In them 2 patients need cystoscopy and ICG-NIRF help to setting up the vessel’s loops. Conclusion The surgeons could always keep the ureter safety during difficult endometriosis dissection with the vessel loops over the ureter as a neck scarf.There will be an indirect traction force pulled by robotic assistant forceps in the regular robotic laparoscopy light source mode during ureterolysis. The Firefly NIRF imaging mode could be used to help in setting up the neck scarf of ureters when the adhesion and fibroisis made the ureters course obscure. Limitations, reasons for caution Indocyanine Green is a fluorescent substance visible in near-infrared light. It is FDA-approved with IV injection for the identification of anatomical structures.The intra-ureteral ICG injection is off-label use. Wider implications of the findings Our techniques could be applied to all pelvic surgeries especially DIE, broad ligament and cervix myoma, scar defect repair and gynecologic cancer surgery, to preventing the ureters injured. However, further studies will be warranted. Trial registration number non-clinical trials

Multiphysics modeling of 3D traction force microscopy with application to cancer cell-induced degradation of the extracellular matrix

Abstract3D Traction Force Microscopy (3DTFM) constitutes a powerful methodology that enables the computation of realistic forces exerted by cells on the surrounding extracellular matrix (ECM). The ECM is characterized by its highly dynamic structure, which is constantly remodeled in order to regulate most basic cellular functions and processes. Certain pathological processes, such as cancer and metastasis, alter the way the ECM is remodeled. In particular, cancer cells are able to invade its surrounding tissue by the secretion of metalloproteinases that degrade the extracellular matrix to move and migrate towards different tissues, inducing ECM heterogeneity. Typically, 3DTFM studies neglect such heterogeneity and assume homogeneous ECM properties, which can lead to inaccuracies in traction reconstruction. Some studies have implemented ECM degradation models into 3DTFM, but the associated degradation maps are defined in an ad hoc manner. In this paper, we present a novel multiphysics approach to 3DTFM with evolving mechanical properties of the ECM. Our modeling considers a system of partial differential equations based on the mechanisms of activation of diffusive metalloproteinase MMP2 by membrane-bound metalloproteinase MT1-MMP. The obtained ECM density maps in an ECM-mimicking hydrogel are then used to compute the heterogeneous mechanical properties of the hydrogel through a multiscale approach. We perform forward and inverse TFM simulations both accounting for and omitting degradation, and results are compared to ground truth reference solutions in which degradation is considered. The main conclusions resulting from the study are: (i) the inverse methodology yields results that are significantly more accurate than those provided by the forward methodology; (ii) ignoring ECM degradation results in a considerable overestimation of tractions and non negligible errors in all analyzed cases.

Poster 192: The Incidence and Breadth of Postoperative Pudendal Nerve Palsy and Its Relationship to Table Traction During Hip Arthroscopy With a Perineal Post

Objectives: Pudendal nerve palsy (PNP) is a poorly characterized but common postoperative complication of hip arthroscopy (HA) with a perineal post that can result in external genital numbness and sexual dysfunction in both men and women. Previous attempts to quantify the incidence of these symptoms have relied on patient-initiated reports, chart review, unvalidated questionnaires or have neglected the female experience altogether – failures which likely underestimate the incidence of this complication. We aimed to describe the incidence of postoperative PNP, the breadth of symptoms patient experience and their duration, as well as establish the relationship between PNP and table traction. Methods: We utilized a multisurgeon prospective cohort of HA patients a single academic center. All patients underwent primary unilateral hip arthroscopy, osteochondroplasty and labral repair in a supine position with a perineal post. Patients with preexisting PNP symptoms, including sexual dysfunction, and those who were not sexually active were excluded. Intraoperative traction duration and force were recorded using a Tekscan sensor applied to the perineal post. A PNP screening questionnaire and standardized, validated sexual function questionnaires were administered confidentially to patients at 2 weeks, 6 weeks, 3 months, and 6 months postoperatively. Patient-reported hip function scores (iHOT-33) were completed preoperatively and at 6 months postoperatively. Results: A total of 100 patients were enrolled. The mean age was 36.2 ± 9.4 years old, 56 patients (56%) were male. The mean traction duration was 80 ± 19 minutes. In the acute postoperative period, 77 patients (77%) experienced symptoms consistent with PNP. The most common sensory symptom described was perineal numbness (n = 77, 77%), followed by paresthesias (n=26, 26%). Seventeen men (17%) and 13 women (13%) reported symptoms of sexual dysfunction postoperatively, in the form of erectile dysfunction (men) or reduced sexual lubrication/dyspareunia/anorgasmia (women). Of patients who experienced PNP symptoms (n = 77), 21% had symptoms resolve by 6 weeks, 71% by 3 months, 90% by 6 months. Two male patients (3.6%) had persistent erectile dysfunction beyond 6 months postoperatively. Persistence of PNP symptoms beyond 6 weeks was associated with lower 33-item International Hip Outcome Tool (iHOT-33) scores at 6 months (mean difference: 18.4 [95% CI: 6.5-30.4], p = 0.003). Analysis of the calibrated sensor data to establish the relationship between traction force, pressure, and duration with PNP is pending. Conclusions: In this preliminary analysis of a planned 100-patient cohort, patients experienced a high rate of PNP and sexual dysfunction symptoms following HA with perineal post, far higher than previous reports. Most symptoms resolved within the first 3 months postoperatively. Anticipated results from the sensor data within this ongoing study are likely to provide insight into the relationship between traction force and/or duration and PNP incidence. A postless HA setup could be considered as an alternative given the described morbidity.