Pressure Mapping Research Articles

3D-printed functionally-graded lattice structure with tunable removal characteristics for precision polishing

Functionally-graded lattice structure (FGLS) has fascinating properties such as lightweight, tunable stiffness, minimized stress concentration, and excellent energy absorption. The advent of 3D printing has provided feasible and reliable manufacturing solutions for FGLS, which has been boosting wider applications of FGLS. In this paper, 3D-printed polishing tools with tunable removal characteristics are developed based on FGLS. The gradient in stiffness is achieved by varying the strut thickness of different cells. Four FGLS with different gradients are designed and printed. The normal contact pressure between the tools and a rigid plate is modelled by the finite element method and experimentally validated with a pressure mapping system. The polishing performance of the developed polishing tools is investigated on both ductile and brittle materials in a machining centre. Results demonstrate that the removal profiles of the polishing tools strictly follow the change of the lattice gradient regardless of the workpiece materials, which mainly affect the depth of the polished footprints. Besides, the surface roughness Sa after polishing reaches as low as 26 nm for the optical glass, indicating a drastic improvement of more than 90%. These findings enable the fabrication of polishing tools with desired tool influence functions on-demand for form error figuring in the computer-controlled optical surface finishing. Besides, the design strategy presented in this paper will open a new realm of producing functional tools in the field of ultraprecision manufacturing. • Functionally-graded lattice structure (FGLS) is designed for polishing. • Contact pressure of FGLS wheel is studied by FEA and validated by experiments. • The FGLS-based polishing tools can produce desired tool influence functions. • The surface finish of optical glass has been improved by > 90% after polishing. • The wear rate of polishing pads is material-dependent.

A literature overview of modern biomechanical-based technologies for bike-fitting professionals and coaches

The optimization of cycling position is essential to improve performance and prevent overuse injuries. Bike-fitting methods, based on biomechanical variables, have been proposed in the scientific literature. To facilitate and generalize their use, the bike-fitting industry has developed various technologies to study and analyze the cycling position. The vast majority of bike-fitting protocols are based on joint kinematics, which can be evaluated in laboratory with two- or three-dimensional motion analysis systems. Joint kinematics can also be assessed in outdoor conditions with inertial measurement units, but currently, these tools provide a limited number of variables compared to laboratory systems. In addition, the bike-fitting professional can analyse pedalling technique with pedal forces to understand the effects of the bike adjustments on pedalling effectiveness. To complete the biomechanical evaluation, pressure mapping sensors allow for the measurement of the pressure load and distribution on the interfaces between the cyclist and the bicycle to detect imbalances and choose bike components (e.g., saddle). To go further in the analysis, muscular activity can be assessed with surface electromyography sensors to detect imbalances or asymmetry. The aim of this literature overview is to clearly define the role of these technologies in a bike-fitting protocol and identify their characteristics and limitations while proposing perspectives for future developments. Therefore, this work is intended for bike-fitting professionals and coaches wishing to choose the most suitable technologies to study and improve the cycling position, and for the bike-fitting industry, in order to optimize existing technologies and help develop new concepts.

Wearable Pressure Sensor Array with Layer-by-Layer Assembled MXene Nanosheets/Ag Nanoflowers for Motion Monitoring and Human-Machine Interfaces.

Recently, wearable sensors and electronic skin systems have become prevalent, which can be employed to detect the movement status and physiological signals of wearers. Here, a pressure sensor composed of mesh-like micro-convex structure polydimethylsiloxane (PDMS), MXene nanosheet/Ag nanoflower (AgNF) films, and flexible interdigital electrodes was designed by layer-by-layer (LBL) assembly. The unique microstructure of PDMS effectively increases the contact area and improves sensitivity. Moreover, AgNFs were introduced into the MXene as a "bridge," and the synergistic effect of the two further enhanced the performance of the sensor. The pressure sensor has high sensitivity (191.3 kPa-1), good stability (18,000 cycles), fast response/recovery time (80 ms/90 ms), and low detection limit (8 Pa), so it can be used for all-round monitoring of the human body. Sensing arrays were integrated with a wireless transmitter as an intelligent artificial electronic skin for spatial pressure mapping and human-computer interaction sensing. Moreover, we develop a smart glove by a simple method, combining it with a 3D model for wireless accurate detection of hand poses. This provides ideas for hand somatosensory detection technology, leading to health monitoring, intelligent rehabilitation training, and personalized medicine.

A comparative analysis of low intensity ultrasound effects on living cells: from simulation to experiments

Ultrasounds are already broadly exploited in clinical diagnostics and are now becoming a powerful and not harmful tool in antitumoral therapies, as they are able to produce damages towards cancer cells, thank to inertial cavitation and temperature increase. The use of US alone or combined to molecular compounds, microbubbles or solid-state nanoparticles is the focus of current research and clinical trials, like thermoablation, drug sonoporation or sonodynamic therapies. In the present work, we discuss on the non-thermal effects of ultrasound and the conditions which enable oxygen radical production and which role they can have in provoking the death of different cancer cell lines. In this perspective, we set a mathematical model to predict the pressure spatial distribution in a defined water sample volume and thus obtain a map of acoustic pressures and acoustic intensities of the applied ultrasound at different input powers. We then validate and verify these numerical results with direct acoustic measurements and by detecting the production of reactive oxygen species (ROS) by means of sonochemiluminescence (SCL) and electron paramagnetic resonance (EPR) spectroscopy, applied to the same water sample volume and using the same US input parameters adopted in the simulation. Finally, the various US conditions are applied to two different set of cancer cell lines, a cervical adenocarcinoma and a hematological cancer, Burkitt’s lymphoma. We hypothesize how the ROS generation can influence the recorded cell death. In a second set of experiments, the role of semiconductor metal oxide nanocrystals, i.e. zinc oxide, is also evaluated by adding them to the water and biological systems. In particular, the role of ZnO in enhancing the ROS production is verified. Furthermore, the interplay among US and ZnO nanocrystals is evaluated in provoking cancer cell death at specific conditions. This study demonstrates a useful correlation between numerical simulation and experimental acoustic validation as well as with ROS measurement at both qualitative and quantitative levels during US irradiation of simple water solution. It further tries to translate the obtained results to justify one of the possible mechanisms responsible of cancer cell death. It thus aims to pave the way for the use of US in cancer therapy and a better understanding on the non-thermal effect that a specific set of US parameters can have on cancer cells cultured in vitro.Graphical abstract

Dynamic finite element analyses to compare the influences of customised total talar replacement and total ankle arthroplasty on foot biomechanics during gait.

Objective, Total talar replacement (TTR) using a customised talus prosthesis is an emerging surgical alternative to conventional total ankle arthroplasty (TAA) for treating ankle problems. Upon satisfying clinical reports in the literature, this study explored the advantages of TTR in restoring foot biomechanics during walking compared with TAA through computational simulations.Methods, A dynamic finite element foot model was built from the MRIs of a healthy participant and modified into two implanted counterparts (TTR and TAA) by incorporating the corresponding prosthetic components into the ankle joint. Twenty bony parts, thirty-nine ligament/tendon units, nine muscle contractors, and bulk soft tissue were included in the intact foot model. The TTR prosthesis was reconstructed from the mirror image data of the participant's contralateral talus and the TAA prosthesis was modelled by reproducing the Scandinavian ankle replacement procedure in the model assembly. The model was meshed with explicit deformable elements and validated against existing experimental studies that have assessed specific walking scenarios. Simulations were performed using the boundary conditions (time-variant matrix of muscle forces, segment orientation, and ground reaction forces) derived from motion capture analyses and musculoskeletal modelling of the participant's walking gait. Outcome variables, including foot kinematics, joint loading, and plantar pressure were reported and compared among the three model conditions.ResultsLinear regression indicated a better agreement between the TTR model and intact foot model in plots of joint motions and foot segment movements during walking (R2 ​= ​0.721–0.993) than between the TAA and intact foot (R2 ​= ​0.623–0.990). TAA reduced talocrural excursion by 21.36%–31.92% and increased (MTP) dorsiflexion by 3.03%. Compared with the intact foot, TTR and TAA increased the midtarsal joint contact force by 17.92% and 10.73% respectively. The proximal-to-distal force transmission within the midfoot was shifted to the lateral column in TTR (94.52% or 210.54 ​N higher) while concentrated on the medial column in TAA (41.58% or 27.55 ​N higher). The TTR produced a plantar pressure map similar to that of the intact foot. TAA caused the plantar pressure centre to drift medially and increased the peak forefoot pressure by 7.36% in the late stance.ConclusionThe TTR better reproduced the foot joint motions, segment movements, and plantar pressure map of an intact foot during walking. TAA reduced ankle mobility while increasing movement of the adjacent joints and forefoot plantar pressure. Both implant methods changed force transmission within the midfoot during gait progression.The translational potential of this article Our work is one of the few to report foot segment movements and the internal loading status of implanted ankles during a dynamic locomotion task. These outcomes partially support the conjecture that TTR is a prospective surgical alternative for pathological ankles from a biomechanical perspective. This study paves the way for further clinical investigations and systematic statistics to confirm the effects of TTR on functional joint recovery.

Interference of Graphene Presence in Formation Mechanism of Metalloporphyrin (PtTFPP) Complex with Oxygen

Introduction Pressure sensitive Paints (PSP) are widely applied in aerodynamic surface tests, as they allow fast data acquisition and pressure mapping across the entire surface during flight simulation [1]. The PSP used in this work is mainly composed of Fluoro-Isopropyl-Butyl (FIB) (Figure 1.A), a polymer that allows oxygen permeability in the paint and platinum tetra(pentafluorophenyl)porphyrin (PtTFPP), responsible for pressure sensitivity (Figure 1.B) [2]. Considering the PSP unique properties, it is possible to obtain an electrical response that enables the use of this paint in airplanes pressure sensors, during flight. For this, an electrical charge of graphene derivative is added to the PSP.Graphene has properties that make it interesting for several applications. Its final application is related to its production method. Electrochemical exfoliation of graphite was used to produce the carbonaceous electrical charge, which has advantages such as ecofriendly reagents, simple product purification and ease of subsequent steps [3, 4]. Seeking to reach the PSP application potential as an oxygen sensitive material that generates an electrical response on pressure, it is necessary that the added electrical charge is compatible with the paint, producing a homogeneous material, high electrical conductivity and mechanical properties suitable for aerospace applications. Thus, the interaction of graphene derivatives with paint and how this influence on its sensitivity to oxygen was studied. This sensitive material can be used in an aeronautical sensor redundant to the Pitot Tube. Therefore, the main objective of the proposed research is to increase the safety of air navigation using a graphene-derived composite with a pressure-sensitive metalloporphyrin paint (PSP).Materials and methods Initially, the production of graphene derivatives was carried out by electrochemical exfoliation of graphite, in which plates of thin graphite sheets pressed were used as working electrode and counter electrode. As an electrolyte solution, a mixture of salts (NH4)2SO4 and (NH4)2HPO4 was used at a concentration of 0.1 mol.L-1 and a proportion of 70/30 v/v%. Exfoliation took place at a fixed potential of 10 V, applied by an electrical power supply. At the end of this process, two drying methodologies were tested: kiln at 70°C (Graphene A) and lyophilization (Graphene B). The composite production consists of mixing the graphene derivative and PSP, at a concentration of 1 mg.mL-1, with the aid of an ultrasound tip for 30 minutes. In addition to the carbonaceous material, a commercial graphene (Graphene C) was also used. After mixing, the material is dripped onto an aluminum surface. The characterizations performed were Raman Spectroscopy and X-Ray Diffraction Spectroscopy to analyze the morphology of the graphene used and Stereo Microscopy, XRD and electrical impedance for the composites.Results and discussion Analyzing the Raman spectra, Graphene A has a more disorder in the carbon chain, higher degree of stacking between planes and a greater association of defects (D4, 2D1 bands, respectively). The lyophilized material showed less interactions between the edges (D1+D4 band) configuring smaller and less agglomerated particles. Graphene C also showed a certain degree of defects and functionalization by oxygenated groups. The diffractogram of Graphene B and C indicates greater disorder in the bonds of the carbon rings with sp2 hybridization than that presented in Graphene A, with A being the material with the highest number of layers and the smallest lamellar distance. Stereo microscopy (Figure 2) images of the composites showed that the mixture is not homogeneous, especially after drying and presents roughness, being these characteristics that can be a problem for the final application. The composite diffractograms show the same peaks only for the paint, with a difference in intensity. The amorphous peak at 16.4°, referring to the polymer, becomes more intense and crystalline with Graphene A and C indicating possible interaction and intercalation of graphene layers with the polymer. The Electrical Impedance of the composites was performed in variable vacuum without flow. Composites with Graphene A and B are resistive, without variation in the presence of different amounts of oxygen. With Graphene C, the response was capacitive-resistive, and was sensitive to pressure changes, but still needs calibration (Figure 3).[1] PUKLIN, E. et al. Ideality of pressure-sensitive paint. I. Platinum tetra(pentafluorophenyl)porphine in fluoroacrylic polymer. Journal of Applied Polymer Science, v. 77, n. 13, p.2795-2804, 2000.[2] GAMAL, E.; et. al. Oxygen pressure measurement using singlet oxygen emission. Review of Scientific Instruments 76, 054101, 2005.[3] KARIMOV, K. S.; et. al. Development of pressure-sensitive thermo-electric cell using graphene and n-Bi2Te3. Emergent Materials 2, pages 387–390, 2019.[4] ANJU, M.; et. al. Graphene-dye hybrid optical sensors. Vol 17, 194 – 217, 2019. Figure 1

Transient triplet differential-based photoacoustic lifetime imaging with an automatic interleaved data acquisition method for improved scanning speed and stability.

Transient triplet differential (TTD) based photoacoustic lifetime (PALT) imaging provides valuable means for background-free molecular imaging and mapping of the oxygen partial pressure (pO2) in deep tissues. However, the broad application of this method is hindered by its long scanning time, poor accuracy, and low stability. This is mainly because most PALT systems execute the three data acquisition sequences separately without automatic control and neglect the long-time fluctuation of the laser output. In this work, we have proposed a novel automatic interleaved data acquisition method for PALT. This new method not only improved the scanning efficiency but also eliminated the long-time fluctuations of laser pulse energy. Results show that this new method can significantly improve the system's stability and help reduce the scanning time. With this new method, we obtained the 3D background-free TTD images for the first time. We also observed distinct hypoxia inside the tumor due to the high metabolic rate of cancer cells, demonstrating the high reliability of our proposed method. The proposed method in this work can significantly promote the application of PALT imaging in biomedical studies.

Transtibial Repair of Lateral Meniscus Posterior Root Tears Improves Contact Biomechanics in Pediatric Cadavers

A paucity of data exists on the treatment of pediatric lateral meniscus root tears (LMPRTs). This study aims to characterize the biomechanics of the lateral knee joint in pediatric cadavers following LMPRT and root repair. Our hypotheses were: (1) compared with the intact state, LMPRT would be associated with decreased contact area; (2) compared with the intact state, LMPRT would be associated with increased contact pressures; and (3) compared with LMPRT, root repair would restore contact area and pressures toward intact meniscus values. Eight cadaver knees (ages 8-12 years) underwent contact area and pressure testing of the lateral compartment. Tekscan pressure mapping sensors covering the tibial plateau were inserted underneath the lateral meniscus. Appropriate pressure load equivalents were applied by a robot at degrees of flexion: 0, 30, 60. Three meniscus conditions were tested: (1) intact, (2) complete root tear, and (3) repaired root tear. Root repairs were performed with transtibial pullout sutures. Statistical analysis was performed. Root tear significantly decreased mean contact area at 30° (P= .0279) and 60° (P= .0397). Root repair increased mean contact area and did not significantly differ from intact states. Differences in contact pressures between meniscus states were not statistically significant. Relative to the intact state. the greatest increase in contact pressures occurred between 0° and 30°. Root repair decreased mean contact pressures at 0° and 30°. At 60°, mean contact pressures of the repair state were closer in magnitude to the tear state than the intact state. Conclusions: LMPRT decreases contact area and increases contact pressures in the lateral knee compartment. Repair of LMPRT improves tibiofemoral contact area at high (>30°) degrees of flexion and contact pressures at low (<30°) degrees of flexion. Transosseous pullout repair is a clinically validated treatment for LMPRT. This study provides baseline biomechanics data of transtibial pullout repair of pediatric LMPRTs.

Functional biomechanical comparison of Latarjet vs. distal tibial osteochondral allograft for anterior glenoid defect reconstruction

Glenoid reconstruction is indicated for recurrent glenohumeral instability with significant glenoid bone deficiency. Coracoid autograft (Latarjet) and distal tibial osteochondral allograft (DTA) reconstructions have been used to successfully restore glenohumeral stability. Relative advantages and disadvantages associated with each reconstruction technique have been described. However, direct comparisons of functional glenohumeral biomechanics associated with Latarjet vs. DTA reconstruction are lacking. This study was designed to compare these 2 glenoid reconstruction techniques with respect to joint kinematics and cartilage pressure mapping using a robotic testing system. In accordance with institutional review board policies, human cadaveric shoulders (n=8) were cyclically tested in the neutral position and 90° of external rotation with 60° and 90° of abduction under a 45-N joint-compression load to measure clinically relevanttranslations, loads, and torques. Joint contact pressure maps were obtained under a 120-N joint-compression load using pressure mapping sensors. After confirming that a 25% anterior glenoid defect resulted in glenohumeral dislocation, testing was performed to compare 3 conditions: native intact glenoid, 25% anterior glenoid defect with Latarjet reconstruction, and 25% anterior glenoid defect with DTA reconstruction. Analyses of variance and t tests were used to analyze data with statistical significance set at P< .05. Significant differences in anterior translation, inferior drawer, anterior drawer, compression loads, horizontal abduction, negative elevation (adduction), and external rotation torques during cyclical testing in 90° of external rotation with 60° and/or 90° of abduction were noted when comparing the 2 different glenoid bone reconstruction techniques to native, intact shoulders. The only significant difference between Latarjet and DTA reconstructions for measured translations, loads, and torques was a significantly higher absolute maximum compressive load for Latarjet compared to DTA at 60° of abduction. Latarjet coracoid osseous autograft and distal tibial osteochondral allograft reconstructions of large (25%) glenoid bone defects prevent failure (dislocation) and are associated with significant glenohumeral kinematic differences that largely confer less translation, load, and torque on the joint in abduction when compared to the native state. These findings suggest that these 2 surgical techniques exhibit similar glenohumeral kinematics such that each provides adequate functional stability following anterior glenoid bone reconstruction. Joint compression load and articular contact pressure distribution may favor distal tibial osteochondral allograft reconstruction for treatment of large (25%) anterior glenoid bone defects associated with shoulder instability.

Computational Modeling of Peritalar Joint Contact Mechanics in Flexible Flatfoot Deformity

Category: Hindfoot; Ankle; Ankle Arthritis Introduction/Purpose: Patients with longstanding progressive collapsing foot deformity (PCFD) often develop osteoarthritis of the peritalar (tibiotalar, subtalar, and talonavicular) joints, which can be symptomatic or can lead to fixed deformities that further complicate the treatment of other sequalae of the deformity (Mann, 1992). Degeneration and subsequent tearing of the arch supporting ligaments leads to altered joint contact mechanics which is a likely causative factor in the development of arthrosis (Hauser and Dolan, 2011). However, the initial effect of ligament tears on changes in joint contact mechanics in the collapsing foot has not been well characterized. The goal of this work was to compare the joint contact mechanics between the neutrally aligned and the flexible flatfoot (collapsed foot). Methods: A validated finite element model of the foot (Malakoutikhah et al., 2022a) was used to compare joint contact pressures between the normally aligned and the collapsed foot. The model of the foot constructed from CT scan images of a female cadaveric foot weighing 60 kg included all 28 bones, 72 ligaments, cartilage, and an encapsulating soft tissue. The model was loaded with 0.5 body weight applied at the center of mass and 0.25 body weight applied to the Achilles tendon simulating quiet stance. The collapsed foot model was created by simulated transection of the plantar fascia, long plantar, short plantar, deltoid, and spring ligaments and unloading of the posterior tibial tendon (Malakoutikhah et al., 2022b). The joint contact pressure maps were determined for both the neutrally aligned and collapsed foot models. The average and peak contact pressures were compared. Results: The peak contact pressures were increased in the tibiotalar and subtalar joints, but paradoxically were decreased in the talonavicular joint in the collapsed as compared to the neutrally aligned foot (Figure 1). The center of pressure was markedly different in all three joints between the neutral and collapsed foot conditions. Specifically, collapsing the foot caused two centers of the talonavicular joint peak pressure to shift towards the central region of the navicular bone, which were evenly distributed in the lateral and medial regions in the neutrally aligned foot. In the subtalar joint, the peak pressure that was uniformly distributed in the lateral and medial regions of the posterior facet in the neutrally aligned foot shifted towards the lateral region in the collapsed foot. Similarly, the peak contact pressure across the tibiotalar joint moved from the center to the lateral region when the foot collapsed. Conclusion: Degenerative tearing of the arch supporting ligaments in PCFD leads to an increase and laterization of the contact pressure in the tibiotalar and subtalar joints with a decrease of the pressure in the talonavicular joint. The paradoxical unloading of the talonavicular joint may be a result of the inability of the malaligned medial column to transmit force from the hindfoot to the forefoot. One implication of this work is that future treatments of PCFD might be directed towards normalizing contact pressure within the peritalar joints to prevent the progression of disease and the development of arthrosis.

Gait analysis driven design and 3D printing of plantar foot orthosis

Customized insoles are generally prescribed to treat or prevent gait modifications and biomechanical changes related to foot deformities that can cause abnormal foot load. These orthoses have the aim of reducing excessive plantar pressures or providing stability or increasing contact area and comfort [1]. Digital scanning, computer-assisted surface modeling techniques, and additive manufacturing are the latest developments in orthotic production. These technologies enable traditional manufacturing processes and designs to be digitalized with control and precision [2]. However, these methods have some limitations: they are still based on the experience of orthopedic technicians [3], only static or bare foot pressure is obtained, unloaded foot shapes are created or inappropriate materials are used for CAD-CAM processing. To overcome these limits, the goal of this study was to develop a method for producing 3D-printed orthoses from plantar pressure data collected through sensorized insoles during walking. A patient with a flat foot was asked to walk barefoot on a treadmill (2 km/h) and then with his shoes on the floor (at self-selected speed), at the orthopedic manufacturer's site during the regular assessment for the production of plantar insoles. Plantar pressure data were acquired both by the instrumented treadmill (I-Runner, Impronta Medica) and by plantar pressure insoles into the shoes (PedarX, Novel gmbh). Afterwards, two different workflows were used to design and produce orthopedic insoles: (1) manufacturer routine methods have been applied, which involves collecting footprints on the instrument treadmill, processing the plantar pressure map through the software Freestep and Easycad Insole (Sensor Medica), producing the insole with the CAD-CAM milling technique; (2) new method involves the use of PedarX data, processed through self-developed codes, and a stl surface generation based on these plantar pressure data. This stl was further processed through the free 3D modeling software Blender and EasyCAD, then the insole was printed with a 3D printer (Bioflex material, straight filling, 90% infill). In Fig. 1 is represented the pipeline of the new method (2). The final result was promising. Since there are no manual interventions by technicians capable of injecting subjectivity into the final product, it ensures that it can be easily reproduced and is consistent with the previously created 3D model. In addition, the possibility of generating the plantar orthosis model from plantar pressure insoles, enables the necessary data to be obtained under free conditions, taking into account the relationship between the foot and the shoe, without the constraints of an instrumented treadmill. As development progresses, comparisons between the two methods of producing insoles will be made, and new filling materials and different filling percentages will be studied to optimize 3D printing.

Medial Meniscus Posterior Root Repair Restores Contact Pressure and Contact Area to Its Native State Even After Opening-Wedge High Tibial Osteotomy: A Cadaveric Biomechanical Study

To elucidate the effect of medial meniscus posterior root (MMPR) repair during opening-wedge high tibial osteotomy (OWHTO) in terms of contact pressure (CP) and contact area (CA). Nine fresh-frozen human cadaveric knee specimens were included. Each specimen was tested under 9 conditions comprising 3 different degrees of correction during OWHTO (neutral, 5° of valgus, and 10° of valgus) and 3 different types of MMPR conditions (intact, torn, and repaired). The prepared specimens were attached to a customized tibiofemoral jig in a fully extended state. The CP and CA generated by a tibiofemoral axial load of 650 N was recorded using the Tekscan sensor's pressure mapping software. Statistical analysis was performed using a repeated measures analysis of variance. The increased CP and decreased CA in torn MMPR was decreased and increased, respectively, to the intact MMPR after repairing, irrespective of whether OWHTO was performed. The mean CP at a correction angle of 5° of valgus was 0.4067 ± 0.0768 MPa for intact MMPR, which increased to 0.7340 ± 0.1593 MPa for the torn MMPR and decreased to 0.3614 ± 0.0639 MPa for the repaired MMPR. In addition, the proportion of decrease in CP and increase in CA after MMPR repair was constant, compared with the torn MMPR, irrespective of the degree of correction during OWHTO. MMPR repair decreases CP and increases CA, irrespective of whether OWHTO is performed. The biomechanical advantage of repairing torn MMPR is maintained, regardless of the degree of correction during OWHTO. Both OWHTO and MMPR repair are known to protect the medial compartment of the knee. However, there are concerns in performing 2 procedures simultaneously. Results of our study showed that concurrent repair of the MMPR during OWHTO is useful for protecting the medial compartment of the knee with respect to tibiofemoral contact biomechanics.

Determining Variability in Arctic Sea Ice Pressure Ridge Topography With ICESat‐2

AbstractWe investigate the characteristics and distribution of pressure ridges in Arctic sea ice using a novel algorithm applied to ICESat‐2 surface heights. We derive the frequency and height of individual pressure ridges and map surface roughness and ridging intensity at the basin scale over three winters between 2019 and 2021. Comparisons with near‐coincident airborne lidar data show that not only can we detect individual ridges 5.6 m wide, but also measure sail height more accurately than the existing ICESat‐2 sea ice height product. We find large regional variability in ridge morphology not only related to parent ice type but also geographic location. Ridge sails are best represented by log‐normal distributions while surface roughness is well fit by an exponential normal function. Our results reveal that high‐resolution satellite altimetry is valuable for characterizing sea ice deformation at short length‐scales and delivers observations that will advance ridging parameterizations in sea ice models.

Mechanical consequences at the tendon-bone interface of different medial row knotless configurations and lateral row tension in a simulated rotator cuff repair

PurposeLittle is known about the direct influence of different technical options at the rotator cuff tendon-bone interface (TBI) and, more specifically, at the medial bearing row (MBR), regarding local contact force, area and pressure. We evaluated the mechanical repercussions of different medial row anchor configurations for that setting using different values of tension in the lateral row anchors.MethodsKnotless transosseous equivalent (TOE) rotator cuff repairs with locked versus nonlocked medial anchors and single versus double-hole suture passage were tested in a synthetic rotator cuff mechanical model, using 2 different values of lateral row tension. Contact force, area, pressure, peak force and MBR force were compared at the simulated TBI using a pressure mapping sensor.ResultsWhen compared to locked anchors, medial row sliding configurations generate lower values for all the above-mentioned parameters.The use of double-hole suture passage in the medial cuff generated slightly higher values contact area regardless of lateral row tension. At higher lateral row tension values, lower values of the remaining parameters, including MBR force, were found when compared to single-hole suture passage.Lateral row anchor tension increase induced an increase of all parameters regardless of the medial row configuration and TBI contact force and MBR force were the most susceptible parameters, regardless of the medial row pattern.ConclusionMedial row mechanism, suture configuration and lateral row tension interfere with the mechanical force, area and pressure at by TBI. Lateral row tension increase is a major influencer in those parameters.These results can help surgeons choose the right technique considering its mechanical effect at the TBI.

Dynamic response characteristics of oil and water distribution during the shut-in period after hydraulic fracturing in shale oil reservoirs

Compared with conventional reservoirs, shale reservoirs are more difficult to develop due to their characteristics of self-generation and self-storage and tightness. Based on the experience accumulated in production practice, the technical method of improving shale oil development through shut-in is put forward. The literature research on shale reservoirs shows that there is a lack of microscopic study on imbibition, the essence of oil–water exchange is not clear enough, and there is a lack of the systematic summary and induction of theoretical knowledge. This article starts from the background of shut-in stimulation of Gulong shale oil, conducts literature research on the related knowledge of shut-in of shale oil from three aspects: characterization of fracture network, shut-in mechanism, and oil and water distribution state, and summarizes the law of shut-in of shale oil in a microscopic aspect. On this basis, a dual-porosity numerical simulation model is established according to the geological and fluid characteristics of the Gulong shale oil reservoir. Through the simulation of a numerical simulation model, the water saturation and pressure maps of the matrix and lamellation-fracture system in the process of shut-in were obtained. It was found that the matrix system basically did not participate in the oil–water exchange in the process of shut-in, so in the subsequent characteristic curve analysis, only the lamellation-fracture system was mapped and analyzed. The water saturation and pressure curves of different distances of the main fracture at different times were made, and it was found that the water saturation and pressure in the main fracture and near fracture areas were higher, and the change was more obvious than that in the far. Thus, the pressure drop curves of the near fracture were used to analyze the flow stage of the fluid. The single variable method is used to analyze the influencing factors from two aspects: the fracture density and permeability of the stimulated zone. The results will give a better understanding of the oil and water distribution during shut-in and guide the duration of shut-in in shale oil reservoirs.

Physics-Informed Neural Networks for Brain Hemodynamic Predictions Using Medical Imaging.

Determining brain hemodynamics plays a critical role in the diagnosis and treatment of various cerebrovascular diseases. In this work, we put forth a physics-informed deep learning framework that augments sparse clinical measurements with one-dimensional (1D) reduced-order model (ROM) simulations to generate physically consistent brain hemodynamic parameters with high spatiotemporal resolution. Transcranial Doppler (TCD) ultrasound is one of the most common techniques in the current clinical workflow that enables noninvasive and instantaneous evaluation of blood flow velocity within the cerebral arteries. However, it is spatially limited to only a handful of locations across the cerebrovasculature due to the constrained accessibility through the skull's acoustic windows. Our deep learning framework uses in vivo real-time TCD velocity measurements at several locations in the brain combined with baseline vessel cross-sectional areas acquired from 3D angiography images and provides high-resolution maps of velocity, area, and pressure in the entire brain vasculature. We validate the predictions of our model against in vivo velocity measurements obtained via four-dimensional (4D) flow magnetic resonance imaging (MRI) scans. We then showcase the clinical significance of this technique in diagnosing cerebral vasospasm (CVS) by successfully predicting the changes in vasospastic local vessel diameters based on corresponding sparse velocity measurements. We show this capability by generating synthetic blood flow data after cerebral vasospasm at various levels of stenosis. Here, we demonstrate that the physics-based deep learning approach can estimate and quantify the subject-specific cerebral hemodynamic variables with high accuracy despite lacking knowledge of inlet and outlet boundary conditions, which is a significant limitation for the accuracy of the conventional purely physics-based computational models.

Using Continuous Intraoperative Pressure Mapping to Describe Patterns of Tissue Interface Pressure.

The purpose of this study was to describe patterns of intraoperative tissue interface pressure, identify the amount of time during which the pressure at four anatomical locations exceeded 32mm Hg, and examine associations between patient- and surgery-related variables and peak tissue interface pressure. We used a pressure mapping system to measure the intraoperative tissue interface pressure of 150 patients. We implemented linear mixed-effects models to assess trends in the mean and peak tissue interface pressure. The percentage of time during which the interface pressure exceeded 32mm Hg at the scapulae, interscapular area, and sacral area was 70%, 70%, and 90%, respectively. Body mass index, length of surgery, and intraoperative position were major predictors of increased pressure. Understanding patterns of tissue interface pressure of patients during surgery may help perioperative nurses develop strategies to attenuate pressure and protect skin integrity.

An overview of the tropical cyclone database at the Central Weather Bureau of Taiwan

Taiwan’s Central Weather Bureau (CWB) has established a new version of tropical cyclone (TC) database to provide users with comprehensive TC data services. As of June 2022, the database includes 1673 TCs originating in the western North Pacific and South China Sea regions since the CWB began TC forecasting operations in 1958. It collects not only the track dataset, satellite imagery, and synoptic weather charts, but also more detailed data and products of TCs that have impacted Taiwan, such as radar reflectivity imagery, high-density surface observations, dropwindsonde data from aircraft observations, and mesoscale analysis maps of rainfall, wind, pressure, and temperature. Such detailed data realistically preserves the TC’s journey across Taiwan and is a feature of the CWB TC database. In addition, the TC database website (https://rdc28.cwb.gov.tw/TDB/) provides tools that allow users to search for TCs of interest based on track, rainfall, and wind. Digital best track data since 1958 is available (https://rdc28.cwb.gov.tw/TDB/manager/obs_data_download/) for users to download and conduct TC research. Also included are technical reports summarizing extensive historical observational research focusing on the mesoscale variations during a TC’s passage over Taiwan. The TC database has been widely used in academic research, disaster prevention, crop revenue insurance, offshore wind power, and other fields. It will continue to develop useful products and integrate more diverse observations to meet the needs of different users.

P4. Independent expansion of the anterior and posterior height of a lateral expandable cage can improve the contact area and load distribution at the cage-endplate interface

<h3>BACKGROUND CONTEXT</h3> Compared to their traditional static counterparts, expandable cages offer clinical advantages by allowing for the use of smaller surgical access corridors to achieve similar lordosis correction without endplate damage from large impaction forces. However, as with static cages, the risk of implant subsidence due to stresses on the vertebral endplate remains an area of concern. Although early clinical outcomes have been reported for individual expandable cage designs, how the endplate contact area and load distribution are affected by specific cage expansion trajectories remains unclear. <h3>PURPOSE</h3> To assess and quantify differences in contact area and load distribution from different lateral expandable interbody cage designs. <h3>STUDY DESIGN/SETTING</h3> Comparative biomechanics analysis using established synthetic spine units. <h3>OUTCOME MEASURES</h3> Cage-endplate contact area, anterior-posterior load distribution, segmental lordosis angle. <h3>METHODS</h3> Discectomies and cage placement were performed on synthetic functional lumbar spine units (n = 3). Three different expandable cage designs were evaluated, each with their own unique expansion trajectory: cranio-caudal, arc-based, and independent anterior and posterior height expansion. For the third cage, a differential expander was used to increase the two heights, anterior and posterior, according to the path of least resistance. A Tekscan calibrated pressure mapping sensor was placed between the cage and the synthetic endplate. The functional spine units were mounted on a servo-hydraulic testing frame and a constant 250N compressive axial preload was applied with unconstrained rotations and translations. The cages were then fully expanded and segmental lordosis angle along with pressure measurements were collected. To allow for a consistent comparison among cages, the surface contact area was normalized by the footprint of each respective cage. To determine the uniformity in the contact load profile, the local load distribution was demarcated in half along the anterior-posterior (A-P) aspect of the cage. The symmetry of the loading profile was characterized by dividing the cumulative anterior force magnitude by the overall force (50% indicates perfectly balanced A-P loading) quantified using the pressure mapping sensor. Friedman's test was performed (α = 0.05) to compare the effect of expansion trajectory on the outcome measures (values reported as median [range]). <h3>RESULTS</h3> Expansion trajectory had a significant effect on cage-endplate contact area and the resultant A-P loading distribution (p = 0.050), but not segmental lordosis angle (p = 0.097). Independent expansion resulted in the highest cage-endplate contact area (93% [92 to 98%]) compared to cranio-caudal (84% [81 to 90%]) and arc-based (62% [56 to 63%]) expansion. Furthermore, independent expansion resulted in a near-even A-P loading distribution (48% [42 to 51%]), compared to cranio-caudal (34% [22 to 36%]), and arc-based (97% [94 to 99%]) expansion. <h3>CONCLUSIONS</h3> Of the cage designs evaluated, the expandable cage with independent anterior and posterior height expansion resulted in the highest cage-endplate contact area and most uniform load distribution, both important considerations fundamental for a successful fusion procedure and the mitigation of implant subsidence risk. With a larger sample size, our continuing studies will investigate the interaction of various cage placement options and expansion mechanisms. <h3>FDA DEVICE/DRUG STATUS</h3> MOD-EX XLIF Interbody System (Approved for this indication), RISE-L Spacer (Approved for this indication)

SOFA Score in relation to Sepsis: Clinical Implications in Diagnosis, Treatment, and Prognostic Assessment.

Purpose To analyze the clinical significance of the sequential organ failure assessment (SOFA) score in the diagnosis, treatment, and prognostic assessment of sepsis. Methods 140 patients with sepsis from January 2020 to January 2021 were selected as the observation group, and 40 healthy people were selected as the control group. The observation group was divided into mild group, severe group, and septic shock group by single blind grouping according to the condition of the disease, and they were also divided into survival group and death group according to the prognosis. Collect the fasting venous blood of the subjects in each group in the morning, compare the levels of total bilirubin (TBIL), blood creatinine (CR), and platelet count (PLT) in each group, and record and compare the patients' respiratory system oxygen partial pressure/inhaled oxygen concentration (po2/fio2), acute physiology and chronic health scoring system II (APACHE II), sequential organ failure assessment (sofa) score, q-SOFA score, and △SOFA score; Pearson analysis was used to analyze the correlation between SOFA score and other indicators; multivariate logistic regression was used to analyze the prognostic risk factors of patients with sepsis; receiver-operating characteristic curve (ROC) was used to analyze the value of SOFA score alone and in combination in the diagnosis, condition, and prognosis of sepsis. Results There were significant differences in Apache II score, SOFA score, q-SOFA score map, po2/fio2, PLT, GCS, TBIL, and serum creatinine (SCR) between the control group and the observation group (P < 0.05). There were significant differences in Apache II score, SOFA score, q-SOFA score, mean arterial pressure (map) po2/fio2, PLT, Glasgow Coma Score (GCS), TBIL, SCR, and △SOFA score among patients in mild, severe, and septic shock groups (P < 0.05). There were significant differences in age, Apache II score, SOFA score, q-SOFA score, map, po2/fio2, PLT, GCS, TBIL, SCR, and △SOFA score between survival group and death group (P < 0.05). SOFA score and q-SOFA score were significantly positively correlated with TBIL and SCR and significantly negatively correlated with po2/fio2 and PLT; △SOFA score was significantly negatively correlated with TBIL and SCR and significantly positively correlated with map, po2/fio2, PLT, and GCS. Apache II score, SOFA score, and q-SOFA score were independent risk factors for sepsis patients, and △SOFA score, po2/fio2, and GCS score were protective factors (P < 0.05). ROC curve analysis showed that the AUC of sepsis combined with SOFA score and q-SOFA score was 0.880; the AUC of sepsis assessed by SOFA score, q-SOFA score, and △SOFA score was 0.929; the AUC of sepsis prognosis assessed by SOFA score, q-SOFA score, and △SOFA score was 0.900. Conclusion SOFA score, q-SOFA score, and △SOFA score were abnormally expressed in patients with sepsis and were risk factors for the severity of the patient's condition and prognosis. The SOFA score, q-SOFA score, and △SOFA score were risk factors for the severity and prognosis of patients with sepsis and had some value in diagnosing sepsis and assessing the condition and prognosis, of which the combined value of the three was higher.