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1
Gu, Haiyu, Zhiming Deng, Yunfeng Yu, Xiaofeng Li, and Baixin Ai. "Modeling and Verification of Cable-Hole Transmission Tension Ratio Considering the Cable Lateral Extrusion." Machines 12, no. 10 (2024): 707. http://dx.doi.org/10.3390/machines12100707.
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Cable-hole transmission is widely applied in cable-driven mechanisms to reduce the mechanical size. However, the driving tension is attenuated with the cable threading through the hole caused by uncertain factors such as local deformation, friction, and other effects, and errors in cable-hole transmission occur. To improve the transmission accuracy of cable-driven mechanisms, a tension distribution model considering the cable lateral extrusion is established. Then, an analytical tension ratio of the cable-hole transmission is derived based on the perturbation method and tension distribution model. Parameters of the tension ratio are identified using a particle swarm optimization algorithm. An adaptive tension control method considering the cable lateral extrusion is designed and compared with the method excluding the cable lateral extrusion in the cable-hole transmission. Finally, a cable-hole transmission experimental device was constructed to verify the tension ratio, parameter identification, and servo control method of the cable-hole transmission. The results show the motion control accuracy of the cable-driven mechanism can be significantly improved with the tension ratio considering the cable lateral extrusion. Compared to the case excluding the cable lateral extrusion, the errors in cable-hole transmission considering the lateral extrusion are reduced by an order of magnitude, and the tension vibration is significantly weakened.
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Walczak, Brian E., Kyle Miller, Michael A. Behun, et al. "Quantifying the differential functional behavior between the medial and lateral meniscus after posterior meniscus root tears." PLOS ONE 16, no. 11 (2021): e0259678. http://dx.doi.org/10.1371/journal.pone.0259678.
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Meniscus tears of the knee are among the most common orthopedic knee injury. Specifically, tears of the posterior root can result in abnormal meniscal extrusion leading to decreased function and progressive osteoarthritis. Despite contemporary surgical treatments of posterior meniscus root tears, there is a low rate of healing and an incidence of residual meniscus extrusion approaching 30%, illustrating an inability to recapitulate native meniscus function. Here, we characterized the differential functional behavior of the medial and lateral meniscus during axial compression load and dynamic knee motion using a cadaveric model. We hypothesized essential differences in extrusion between the medial and lateral meniscus in response to axial compression and knee range of motion. We found no differences in the amount of meniscus extrusion between the medial and lateral meniscus with a competent posterior root (0.338mm vs. 0.235mm; p-value = 0.181). However, posterior root detachment resulted in a consistently increased meniscus extrusion for the medial meniscus compared to the lateral meniscus (2.233mm vs. 0.4705mm; p-value < 0.0001). Moreover, detachment of the posterior root of the medial meniscus resulted in an increase in extrusion at all angles of knee flexion and was most pronounced (4.00mm ± 1.26mm) at 30-degrees of knee flexion. In contrast, the maximum mean extrusion of the lateral meniscus was 1.65mm ± 0.97mm, occurring in full extension. Furthermore, only the medial meniscus extruded during dynamic knee flexion after posterior root detachment. Given the differential functional behaviors between the medial and lateral meniscus, these findings suggest that posterior root repair requires reducing overall meniscus extrusion and recapitulating the native functional responses specific to each meniscus.
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Ayer, Önder, Sedat Bingöl, and Tahir Altinbalik. "Artificial Neural Network Modeling of Injection Upsetting Load Prediction." Applied Mechanics and Materials 729 (January 2015): 155–60. http://dx.doi.org/10.4028/www.scientific.net/amm.729.155.
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Lateral extrusion, which requires less forming load comparing the closed-die forging, has been presenting a gradually increasing field of application as a type of metal forming wherein advantageous of forging and extrusion are combined. In this study production of a work piece with a single tapered tooth manufactured by the lateral extrusion method has been made and experimental load and die fullness rates have been measured. After that the data obtained from experiments was submitted to the developed artificial neural networks (ANN) model. The ANN model was trained by taking diameter, height and stroke as the input variables and the injection upsetting load as the output parameter. The ANN predicted results were found to be in terms of prediction accuracy with experimental results.
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GRIFFITHS, ROSS W., and JONATHAN H. FINK. "Solidifying Bingham extrusions: a model for the growth of silicic lava domes." Journal of Fluid Mechanics 347 (September 25, 1997): 13–36. http://dx.doi.org/10.1017/s0022112097006344.
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In a previous study of the effects of cooling and solidification on flows issuing onto a horizontal plane and spreading under gravity we considered the case of a viscous fluid that solidifies to form a thin surface crust with a finite yield strength. In that case, the coupling of solidification and viscous stresses in the flow led to a sequence of flow regimes or styles of flow and crustal deformation. Here, we study the spreading, from a small source, of a plastic material having a yield strength before cooling. In this case the fluid again begins to freeze as it spreads radially under gravity, and forms a dome having a surface crust which is stronger than the extruded fluid. If cooling is sufficiently rapid compared to gravity-driven spreading, the flow is found to be controlled by solidification. The flow again takes on one of a number of flow regimes depending on the pace of solidification relative to the rate of lateral flow, or extrusion rate. However, these flow regimes are quite different from those for the viscous extrusions, implying that the internal yield stress has a strong influence on the behaviour. Styles of flow ranged from inflation of an axisymmetric dome to irregular extrusion of lateral lobes and vertical spines. These qualitatively different regimes have much in common with the eruption styles of volcanic lava domes produced by effusion of extremely viscous silicic magmas which may possess a yield strength, and the model provides information about the factors influencing the morphology and hazards of such volcanic flows.
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Hynes, A. "Encouraging the extrusion of deep-crustal rocks in collisional zones." Mineralogical Magazine 66, no. 1 (2002): 5–24. http://dx.doi.org/10.1180/0026461026610013.
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AbstractMost unroofing mechanisms invoked for the exhumation of blueschist-plus-eclogite terranes, including corner-flow and extensional collapse of the orogenic wedge, predict steep unroofing paths for the deeply-buried rocks and are applicable only to unroofing from depths within the crust. Many high-P and ultrahigh-P rocks of continental affinity are derived from greater depths than this. Their lack of warming during unroofing, together with indications that they may rest directly on less deeply buried equivalents, are suggestive of shallow unroofing paths similar to those for the subduction-channel model. They are interpreted to have been emplaced by the upward extrusion of coherent slices of continental crust, bounded below by thrust faults and above by normal faults, with unroofing paths essentially reversing the original burial paths.Where continental crust has been subducted into the mantle, upward extrusion is probably driven largely by buoyancy forces, although examples of upward extrusion without subduction into the mantle indicate that buoyancy forces may not be essential. Two features in addition to buoyancy may promote upward extrusion. Slab breakoff may reduce the pull from the descending slab, and subduction-zone geometry may change as a continental margin is dragged into the subduction zone. Both features may promote the extrusion of continental crust at precisely the time at which it has been partially subducted.A close spatial relationship between a lateral ramp and a lobate zone of extruded high-P rocks in the Mesoproterozoic Grenvillian orogen indicates that lateral ramps may be important in localizing extrusion. Lateral ramps disturb the two-dimensional flow, with channelling of material into the region of the lateral ramp as it is extruded. Many exhumed ultrahigh-P terrains are associated with jogs in the trends of orogenic fronts that may reflect the presence of lateral ramps at depth. Ultrahigh-P rocks may be expected to be concentrated at such jogs, and may record the channelling in their deformation history.
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Haghighat, H., and D. Almasi. "Lateral Extrusion of Gear-Like Components with Radial Tooth Profile: Metal Flow Simulation and Analysis." Advanced Materials Research 264-265 (June 2011): 72–77. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.72.
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The process of lateral extrusion of gear-like components with radial tooth profile has been studied in this paper. The material flow in extrusion die cavity has been simulated using the SuperForge of FVM simulation package. The results of simulation have shown that the material fills the die cavity in two stages: Parallel movement to the end of toothed die cavity and fills the rest of shaped die cavity. Each stage of deformation has been analyzed by using slab method of analysis and the extrusion load values for each punch stroke have been estimated. Finally, comparisons between present theoretical results and experiments of other researchers’ work have been carried out to illustrate the validity of this proposed model.
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Khan, Yawar Abbas, and Henry Sigvart Valberg. "Aluminium Extrusion Weld Formation and Metal Flow Analysis in Hollow Profile Extrusions of Different Section Thickness." Key Engineering Materials 491 (September 2011): 105–12. http://dx.doi.org/10.4028/www.scientific.net/kem.491.105.
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Hollow and semi-hollow profiles are commonly produced by extrusion using porthole dies. The main characteristics of such dies are the presence of a mandrel (core) to shape the inner contour of hollow profile and bridges or legs to carry the mandrel. The bridges split the billet material into multiple metal streams that flow through the porthole channels and meet in the welding chamber behind the bridge where they are joined by pressure welding. When hollow profiles with different wall thickness are made the size of two adjacent portholes may be different. The material then flows through the two portholes with different flow velocity so that there is more feed through the bigger porthole into the weld chamber behind the bridge. Experiments have been performed and are reported here in which a grid pattern technique was used to characterize the metal flow through a 2D-die with porthole channels of unequal size. The design of the laboratory die has been modified in relation to the symmetric case to get different sizes of the two portholes. Since the metal flow through such a die is asymmetric the grid pattern technique was also modified to characterize the experimental flow. The results of an experimental metal flow study performed for a short billet was presented in a previous article [1]. Corresponding experiments performed with longer billets are now reported; so that two stages of the extrusion process is analysed here. The grid pattern technique has successfully mapped the non-symmetric material flow as in industrial extrusion when using different wall thickness over the section. The lateral movement of metal during extrusion is obtained from one set of experiments; the vertical movement from the other set. Finite element analysis of the extrusion process has been performed using Deform 3D. The encountering of the two metal streams behind the die bridge and the deformation characteristics within the welding chamber has been studied this way. Extrusion weld formation and deformations around the die bridge are considered here with the help of experimental results and simulation models. The nature of the metal flow achieved from the FE-model is compared with the experimental results. As regards the short billet some results are presented in [1], however improvement to the previous model gives a more perfect match. The model also provides information about the boundary conditions in real extrusion.
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Tevelev, Al V., I. A. Prudnikov, Ark V. Tevelev, A. O. Khotylev, and E. A. Volodina. "KINEMATICAL MODEL FOR FORMING THE SIMEAN LOW OF THE URALIAN FORELAND BASIN." Moscow University Bulletin. Series 4. Geology, no. 2 (April 28, 2018): 23–32. http://dx.doi.org/10.33623/0579-9406-2018-2-23-32.
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In this work we reported the structural features and mechanism of the formation of the Simskaya low of the Uralian foreland basin, besides the Karatau-Suleyman block as a whole. This block has the shape of a wedge, so with a general latitudinal compression, it experienced lateral extrusion to the north along the conjugated shear zones. This factor determined the local situation of meridional compression and latitudinal tension. In the central part of the block, the latitudinal stretching was compensated for by gradual deflection, which led to the formation of the Simskaya low.
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Behrens, Bernd-Arno, Christian Klose, Alexander Chugreev, Norman Heimes, Susanne Thürer, and Johanna Uhe. "A Numerical Study on Co-Extrusion to Produce Coaxial Aluminum-Steel Compounds with Longitudinal Weld Seams." Metals 8, no. 9 (2018): 717. http://dx.doi.org/10.3390/met8090717.
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The use of lightweight materials is one possibility to limit the weight of vehicles and to reduce CO2 emissions. However, the mechanical properties and weight-saving potential of mono-materials are limited. Material compounds can overcome this challenge by combining the advantages of different materials in one component. Lateral angular co-extrusion (LACE) allows the production of coaxial semi-finished products consisting of aluminum and steel. In this study, a finite element model of the LACE process was built up and validated by experimental investigations. A high degree of agreement between the calculated and experimentally determined forces, temperatures, and the geometrical shape of the hybrid profiles was achieved. In order to determine suitable parameters for further extrusion experiments, the influence of different process parameters on material flow and extrusion force was investigated in a numerical parametric study. Both the temperature and extrusion ratio showed a significant influence on the occurring maximum extrusion force as well as the material flow inside the LACE tool. The maximum force of 2.5 MN of the employed extrusion press was not exceeded. An uneven material flow was observed in the welding chamber, leading to an asymmetric position of the steel rod in the aluminum matrix.
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Smith, Patrick A., Will A. Bezold, Cristi R. Cook, et al. "Kinematic Analysis of Lateral Meniscal Oblique Radial Tears in the Anterior Cruciate Ligament–Deficient Knee." American Journal of Sports Medicine 49, no. 14 (2021): 3898–905. http://dx.doi.org/10.1177/03635465211052521.
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Background: Lateral meniscal oblique radial tears (LMORT) occur frequently in conjunction with anterior cruciate ligament (ACL) disruption and are anatomically distinct from meniscus root tears. Hypothesis/Purpose: The purpose of this study was to characterize the effects of LMORT types 3 (LMORT3) and 4 (LMORT4) lesions on joint stability and meniscal extrusion in ACL-deficient knees. Our hypothesis was that both lesions would promote significant increases in anterior translation and meniscal extrusion, with the LMORT4 lesion having a greater effect. Study Design: Controlled laboratory study. Methods: Two matched pairs of cadaveric knees (n = 4) were used to optimize the testing sequence. Additional cadaveric knees with LMORT3 (n = 8) and LMORT4 (n = 8) lesions created after ACL transection underwent robotic kinematic testing for anterior drawer and pivot-shift simulations with associated ultrasound-measured meniscal extrusion at clinically relevant knee flexion angles. Results: Optimization testing showed no differences on the effect of LMORT4 lesions for anterior translation and lateral meniscal extrusion with ACL-intact versus ACL-deficient knees. ACL deficiency and LMORT3 and LMORT4 lesions with ACL deficiency were associated with significantly greater anterior translation compared with ACL-intact state for both anterior drawer and pivot-shift testing at all flexion angles ( P < .001). ACL deficiency with either LMORT3 or LMORT4 lesion was associated with significantly greater anterior translation than was ACL deficiency only ( P < .005) for anterior drawer testing at 90° of flexion. Meniscal extrusion was greater with LMORT3 and LMORT4 lesions compared with ACL deficiency only ( P < .05) for anterior drawer at 60° of flexion and for pivot shift at 15° of flexion. The LMORT4 lesion demonstrated increased anterior translation for anterior drawer ( P = .003) at 60° of flexion (12%) as well as for pivot shift at 15° of flexion (7%) and 30° of flexion (13%) ( P < .005) compared with ACL deficiency only. Conclusion: In this cadaveric model, the addition of an LMORT3 or LMORT4 lesion increased anterior laxity for both the anterior drawer and the pivot shift when compared with an isolated ACL tear. Lateral meniscal extrusion was also exacerbated by these LMORT lesions. Clinical Relevance: LMORT lesions, distinct from meniscus root tears, occur frequently in conjunction with ACL tears. This study characterized the biomechanical consequences of LMORT3 and LMORT4 lesions on joint stability and meniscal function, highlighting the importance of diagnosing and treating LMORT lesions at the time of ACL reconstruction.
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Yang, Youqing, and Mian Liu. "Crustal thickening and lateral extrusion during the Indo-Asian collision: A 3D viscous flow model." Tectonophysics 465, no. 1-4 (2009): 128–35. http://dx.doi.org/10.1016/j.tecto.2008.11.002.
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Wölfler, Andreas, Walter Kurz, Harald Fritz, and Kurt Stüwe. "Lateral extrusion in the Eastern Alps revisited: Refining the model by thermochronological, sedimentary, and seismic data." Tectonics 30, no. 4 (2011): n/a. http://dx.doi.org/10.1029/2010tc002782.
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Zhang, Wei Bing, and Lian Tang. "Settlement and Deformation Laws of High Loess-Filled Embankment Based on Centrifugal Model Test." Applied Mechanics and Materials 90-93 (September 2011): 222–29. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.222.
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In view of the settlement problem of high loess-filled embankments themselves, with the reference of the 30m high embankment at K5 +536 of Lan Lin provincial expressway and by means of the centrifugal model test, the developing process of the settlement for embankment itself with time in different sections of embankment and the distribution laws of the settlement subjected from spatial effect in case of the different terrain conditions are studied. Compared with the actual measurement, the results show that: as far as the settlement of high-filled embankment itself is concerned, the settlement at the central part along the cross-section of embankment is larger than that at shoulder; When the stability of embankment is relatively poor because of the bigger slope ratio or faster speed of construction, the settlement at the shoulder caused by the lateral extrusion from the edge of embankment is larger; The settlement of embankment itself is approximately 0.5% -1% of the height of embankment, about 75% -85% of which occurred during the construction period and the remaining 15% -25% belongs to after construction. Furthermore, the 85% of the settlement belong to after construction will be completed within a year and about two years later the settlement tend to be stable; Owing to the affection of the spatial effect due to the valley terrain conditions, the settlement near the joint sites between the embankment and the gully is larger than that occurred in gentle slope and the central part of embankment. During the time of designing and construction for high-filled embankment, the location where the settlement influenced by the lateral extrusion and spatial effect should be paid attention to, so that, the security and stability of the embankment could be ensured.
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Hynes, Andrew, Aphrodite Indares, Toby Rivers, and André Gobeil. "Lithoprobe line 55: integration of out-of-plane seismic results with surface structure, metamorphism, and geochronology, and the tectonic evolution of the eastern Grenville Province." Canadian Journal of Earth Sciences 37, no. 2-3 (2000): 341–58. http://dx.doi.org/10.1139/e99-076.
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Lithoprobe line 55, in the Grenville Province of eastern Quebec, provides unusually good control on the three-dimensional (3-D) geometry and structural relationships among the major lithological units there. Archean basement underlies the exposed Proterozoic rocks, along the entire seismic line, and there is a lateral ramp in this basement immediately behind a lobate stack of thrust slices of high-pressure metamorphic rocks comprising the Manicouagan Imbricate Zone (MIZ). Integration of the 3-D geometry with P-T and geochronological data allows derivation of a tectonic model for the region. The MIZ was buried to depths >60 km at 1050 Ma. Preservation of its high-pressure assemblages, and the absence of metamorphism at 990 Ma, which is characteristic of lower pressure metamorphic rocks that tectonically overlie them, indicates the MIZ rocks were rapidly unroofed, early in the tectonic history. There were two discrete pulses of crustal thickening during the Grenvillian Orogeny in this region. The first, involving imbrication of Labradorian and Pinwarian rocks that comprised part of southeast Laurentia, culminated in the Ottawan pulse at ca. 1050 Ma, and produced the high-pressure metamorphism of the MIZ. Its effects were rapidly reversed, with extrusion of the MIZ rocks to shallow crustal levels at ca. 1020 Ma. The crust was again thickened, with the Moho subsiding to depths >60 km, in the Rigolet pulse at ca. 990 Ma. The site of extrusion of the MIZ was probably controlled by the subsurface lateral ramp. High geothermal gradients indicate that extrusion may have been aided by lithospheric delamination in the crustal-thickening zone.
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Schongen, Fabian, Fritz Klocke, Patrick Mattfeld, Sergej Rjasanow, Marvin Fleck, and Richards Grzhibovskis. "Time-Efficient and Precise FEM/BEM Simulation of a Cold Forging Process Verified by Tool Load Determination." Key Engineering Materials 554-557 (June 2013): 317–27. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.317.
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Developing green processes establishes new possibilities for cold forging industry. Current technological developments require automotive parts with less mass, but higher material-efficiency. To achieve these goals, high-strength steels and complex geometries are used. The rising process forces lead to increased tool loads and subsequently elastic tool deformation resulting in early tool failure or dimensional deviations. A numerical determination of tool loads during process enables their reduction by a load-dependent design of the tool geometry. Aim of this work is a time-efficient and precise determination of tool loads considering the complete tool system using the example of a lateral extrusion process. By domain decomposition into Finite Element Method (FEM) and Boundary Element Method (BEM) domains and subsequently an integrated FEM/BEM simulation, a significant computation time reduction towards a conventional FEM model is achieved. Experiments of the examined lateral extrusion process provide data for the verification of the investigated process simulation models. In order to be able to validate the simulated elastic tool deformations, strain gauges are installed on the die insert and allow an experimental measurement of the elastic radial die strains. Additionally the simulated process force development and the final workpiece geometry of the simulation models are compared with experimental results.
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Pelletier, Jean-Pierre, Patrice Paiement, Marc Dorais, Jean-Pierre Raynauld, and Johanne Martel-Pelletier. "Risk factors for the long-term incidence and progression of knee osteoarthritis in older adults: role of nonsurgical injury." Therapeutic Advances in Chronic Disease 14 (January 2023): 204062232311697. http://dx.doi.org/10.1177/20406223231169715.
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Background: For one of the most chronic medical conditions, osteoarthritis, uncertainties remain on the impact of injury chronology, the role of repeat injury on the incidence/progression of this disease and the need for knee arthroplasty. Objectives: To explore, in an older adult population, how nonsurgical knee injuries relate to osteoarthritis incidence/progression and the weight of independent risk factors for arthroplasty. Design: A cohort study design evaluates the long-term impact of injuries on knee osteoarthritis outcomes. Methods: Knees with no prior injury ( n = 6358) and with at least one injury ( n = 819) ⩽20 years before study inclusion were from the Osteoarthritis Initiative cohort. Sociodemographic, clinical and structural [X-ray, magnetic resonance imaging (MRI)] data at study inclusion and changes within 96 months were analysed. Statistics included a mixed model for repeated measurements, generalized estimating equations and multivariable Cox regression with covariates. Results: At inclusion, knees with prior injury demonstrated greater incidence and severity of osteoarthritis ( p ⩽ 0.001). At 96 months, there was a greater increase in symptoms [Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, p = 0.002], joint space width (JSW, p = 0.039) loss, medial cartilage volume loss (CVL, p ⩽ 0.001) and bone marrow lesion size (BML, p ⩽ 0.049). Knees with/without injury at inclusion but with new ones over time had a pronounced increase in symptoms (all WOMAC scores, p ⩽ 0.001), JSW loss, lateral (without) and medial CVL, lateral (without) and medial meniscal extrusion and medial BML (without; all p ⩽ 0.030). Levels of lateral and medial meniscal extrusion (without) and symptoms (with/without; all WOMAC scores, p ⩽ 0.001) were all accentuated with a repeated new injury. Risk factors associated with the highest knee arthroplasty occurrence are new meniscal extrusion and new injury ( p ⩽ 0.001). Conclusion: This study highlights the importance of nonsurgical knee injury in older adults as an independent risk factor for knee osteoarthritis and arthroplasty. These data will be beneficial in clinical practice as they will help identify individuals at greater risk of significant disease progression and worst disease outcomes for a customized therapeutic approach.
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Liu, Yanchang, Yiren Pan, Xuehua Hu, and Fang Yu. "Squeezing Mechanical Analysis and Model Establishment of the Viscoelastic Rubber-Strip-Feeding Process of the Cold-Feed Rubber Extruder." Polymers 14, no. 17 (2022): 3602. http://dx.doi.org/10.3390/polym14173602.
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In the process of rubber extrusion, the feed structure directly affects the extrusion quality, extrusion uniformity, screw lateral force, and feed power consumption. Until now, the feed structure was mainly based on empirical designs, and there was no theoretical model for the optimal design of a feed structure. This paper focused on the squeezing mechanical analysis and model establishment of the feeding process in which viscoelastic rubber strips are passed through feed-wedge clearance in cold-feed extruders. The screw flight rotation squeezing process was simplified into a disc rotation squeezing process; the instantaneous squeezing velocity in the disc rotation squeezing model was derived according to feed wedge clearance geometry and the disc rotating speed. By transforming rotation squeezing into differential slab squeezing, mathematical expressions of the velocity distribution, pressure distribution, total squeezing force, and power consumption in the feeding process were derived in a rectangular coordinate system under isothermal and quasi-steady assumptions and certain boundary conditions by using balance equations and a Newtonian viscous constitutive relation. Theoretical calculations and experimental values showed the same trend. Through comparison, it was found that the power consumption (P3) caused by sliding friction is about 200–900 W according to theoretical calculations, while the experimental test results show it to be about 300–700 W. Additionally, the difference between theoretical pressure value and the experimental pressure value can be controlled within 5–15%. This could reflect the main factors that affect the feeding process, so could be used for analyses of actual feeding problems, and to contribute to rough quantitative descriptions of the feeding process, finite element simulation, and the optimization of the feeding structure.
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Grechnikov, Fedor V., Alexander I. Khaimovich, V. Mikhelkevich, and Cho-Pei Jiang. "The Research of Friction Influences on the Formation Process by Lateral Extrusion into Radial Wedge-Type Branches." Key Engineering Materials 746 (July 2017): 56–62. http://dx.doi.org/10.4028/www.scientific.net/kem.746.56.
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The article represents theoretical analysis of friction influence on the process of formation experimental blank with several radial wedge-type branches having different constituent convergence angles. The authors show that with the correlation between volumes of material what are extruded into the branches it is possible to define the friction coefficient for set conditions of forging. Such approach allows suggesting the methodology for exact definition of friction coefficient for forged blank with a large area of contact surface. For the analysis the analytical model is used which was obtained by upper-bound approach technique. Calibration measurement of accuracy of a model was carried out by numerical method in Deform 3D.
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Zhang, Li Hua, Li Yu, and Zhe Jun Quan. "Moisture Content's Influence to Pile Bearing Capacity and Finite Element Analysis." Applied Mechanics and Materials 633-634 (September 2014): 922–26. http://dx.doi.org/10.4028/www.scientific.net/amm.633-634.922.
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This essay analyzes stress between pile and soil, occupying moisture content data of unsaturated soil in Nanchang with ANSYS. In accordance with engineering practice, it adopts three-dimensional solid model, the same geometric size with engineering practice. It simulates interrelation between pile and soil with contact unit, and shows ontology relation of soil with D-P elastic-plastic model. Convergence has been made with selection and calculation of parameter. The greater the moisture content gets, the smaller the pile body vertical displacement makes. In other words, the smaller the relative displacement between pile and soil gets, the lower the lateral extrusion stress from pile to soil becomes. Keywords: unsaturated soil; shear strength; pile bearing capacity; finite element analysis; moisture content
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BATON, L. A., and L. C. RANFORD-CARTWRIGHT. "Plasmodium falciparumookinete invasion of the midgut epithelium ofAnopheles stephensiis consistent with the Time Bomb model." Parasitology 129, no. 6 (2004): 663–76. http://dx.doi.org/10.1017/s0031182004005979.
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Plasmodium falciparumgametocytes grownin vitrowere fed through membrane feeders to laboratory-rearedAnopheles stephensimosquitoes. Intact midguts, including entire bloodmeal contents, were removed between 24 and 48 h post-bloodfeeding. Giemsa-stained histological sections were prepared from the midguts and examined by light microscopy. Contrary to previous reports, ookinetes were clearly visible within midgut epithelial cells, demonstrating intracellular migration across the midgut wall. Ookinetes entered epithelial cells through the lateral apical membrane at sites where 3 adjacent cells converged. There was no evidence for the existence of a morphologically distinct group of epithelial cells preferentially invaded by ookinetes. However, ookinete penetration was associated with significant morphological changes to invaded cells, including differential staining, condensation and fragmentation of the nucleus, vacuolization, loss of microvilli and various degrees of extrusion into the midgut lumen. Epithelial cells completely separated from the midgut wall were found within the midgut lumen. These cells were associated with invading parasites suggesting that ookinete penetration resulted in complete ejection of invaded cells from the midgut wall. Small clusters of morphologically altered midgut cells and invading parasites spanning the membranes of adjacent abnormal epithelial cells were observed, consistent with intracellular movement of ookinetes between neighbouring midgut cells. Extruded epithelial cells were also observed rarely in uninfected midguts. Epithelial cell extrusion, therefore, may be a general mechanism of tissue repair through which damaged cells are removed from the midgut wall rather than a parasite-specific response. These observations demonstrate that human malaria parasite infection of mosquitoes is consistent with, and provides further support for, the Time Bomb model of ookinete invasion of the mosquito midgut epithelium previously proposed for rodent malaria parasites.
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Smith, Patrick A., Will A. Bezold, Cristi R. Cook, et al. "Kinematic Analysis of Lateral Meniscal Oblique Radial Tears in Anterior Cruciate Ligament–Reconstructed Knees: Untreated Versus Repair Versus Partial Meniscectomy." American Journal of Sports Medicine 50, no. 9 (2022): 2381–89. http://dx.doi.org/10.1177/03635465221102135.
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Background: Lateral meniscal oblique radial tears (LMORTs) affect joint and meniscal stability in anterior cruciate ligament (ACL)–deficient knees. Purpose: To determine the clinically relevant kinematics associated with the most common posterior horn LMORT lesion types, types 3 (LMORT3) and 4 (LMORT4), untreated versus arthroscopic repair versus partial meniscectomy in combination with ACL reconstruction (ACLR). Study: Controlled laboratory study. Methods: Sixteen cadaveric knees underwent robotic testing for anterior drawer and pivot-shift simulations at multiple knee flexion angles in ACL-intact and ACL-deficient states, followed by sequential testing of arthroscopic ACLR, LMORT3 lesion, LMORT3 repair, and partial meniscectomy (n = 8). The same testing sequence was performed for LMORT4 lesions (n = 8). Results: ACLR restored kinematics in ACL-deficient knees to intact levels for all metrics tested. For anterior drawer, ACLR + LMORT3 tear and partial meniscectomy resulted in significantly greater anterior translation compared with ACL-intact at all angles ( P < .05) and compared with ACLR at 60° and 90° ( P < .014). For pivot shift, compared with ACL-intact knees, ACLR + LMORT3 tear resulted in significantly more anterior translation at 15° ( P = .041); and for ACLR + partial meniscectomy, at both 0° and 15° ( P < .03). ACLR + LMORT4 tear and partial meniscectomy resulted in significantly greater anterior translation for anterior drawer ( P < .04) and pivot-shift testing ( P < .05) compared with intact and ACLR knees at all angles tested. ACLR + LMORT3 repair and ACLR + LMORT4 repair restored kinematics to ACLR and intact levels at all angles tested. ACLR + LMORT3 tear ( P < .008) and both LMORT4 tear and partial meniscectomy ( P < .05) resulted in increased meniscal extrusion compared with intact and ACLR statuses at all tested angles for anterior drawer and pivot shift, while repairs restored meniscal stability to ACLR and intact levels. Conclusion: Untreated LMORT tears increased anterior translation, pivot shift, and meniscal extrusion after ACLR, while partial meniscectomy further exacerbated these detrimental effects in this cadaveric model. In contrast, arthroscopic side-to-side repair of LMORT lesions effectively restored measured knee kinematics. Clinical Relevance: LMORT lesions are common with ACL tears and adversely affect joint stability and meniscal extrusion. This study highlights the importance of repair of LMORT 3 and 4 lesions at the time of ACLR.
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Su, Zhe, Xi-Wei Xu, Shan-Shan Liang, and Erchie Wang. "Seismotectonics of the 2017–2018 Songyuan Earthquake Sequence, Northeastern China: Passive Bookshelf Faulting and Block Rotation in the Songliao Basin." Seismological Research Letters 91, no. 3 (2020): 1593–605. http://dx.doi.org/10.1785/0220190251.
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Abstract The high frequency of earthquake clusters generated by pure strike-slip faulting over the past 3 yr (beginning in 2017 in the Songliao basin, northeastern China) has motivated us to consider why lateral strike slip and not extension determines the seismic activity within the Songliao basin. Precise location and characterization of relocated aftershocks, forward modeling of the coseismic displacement field, and Global Positioning System (GPS) monitoring data are combined to detect the possible seismogenic structures of the Songyuan earthquake sequence. The 2017 ML 5.3 aftershock cluster coincided with the northeast-striking Fuyu–Zhaodong fault (FZF), and the 2018 aftershock swarm followed the linear trend (N42°W) of the Songhuajiang fault (SHF). In addition, the forward modeling results indicate that during the earthquakes, right-lateral and left-lateral strike-slip displacements occurred simultaneously along the FZF and SHF, respectively. These two strike-slip faults joined to accommodate the intervening crustal blocks’ asymmetrical east–west convergence and a single northward extrusion. We also utilize 5 yr of GPS data to construct the regional strain-rate map for the basin. The measurements show that right-lateral transform motion along the immense northeast-striking right-lateral strike-slip faults, for example, the Tanlu fault zone and the FZF, impose a northeast-striking simple shear across the Songliao basin. This simple shear not only caused left-lateral movement on the minor northwest-striking left-lateral strike-slip faults such as the SHF but also rotated them ∼14° clockwise into their present orientations. The results of the proposed bookshelf faulting model in which the predominant northeast-striking parallel faults are initiated are consistent with the observed lineament orientations, focal mechanisms, and earthquake distributions. The sharp shift in the subduction direction of the Pacific plate seems to have had a considerable influence on the intracontinental deformation in China, at least throughout northeastern China.
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Behrens, Bernd-Arno, Hans Jürgen Maier, Christian Klose, et al. "Characterization and Modeling of Intermetallic Phase Formation during the Joining of Aluminum and Steel in Analogy to Co-Extrusion." Metals 10, no. 12 (2020): 1582. http://dx.doi.org/10.3390/met10121582.
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The reinforcement of light metal components with steel allows to increase the strength of the part while keeping the weight comparatively low. Lateral angular co-extrusion (LACE) offers the possibility to produce hybrid coaxial profiles consisting of steel and aluminum. In the present study, the effect of the process parameters temperature, contact pressure and time on the metallurgical bonding process and the development of intermetallic phases was investigated. Therefore, an analogy experiment was developed to reproduce the process conditions during co-extrusion using a forming dilatometer. Based on scanning electron microscopy analysis of the specimens, the intermetallic phase seam thickness was measured to calculate the resulting diffusion coefficients. Nanoindentation and energy dispersive X-ray spectroscopy measurements were carried out to determine the element distribution and estimate properties within the joining zone. The proposed numerical model for the calculation of the resulting intermetallic phase seam width was implemented into a finite element (FE) software using a user-subroutine and validated by experimental results. Using the subroutine, a numerical prediction of the resulting intermetallic phase thicknesses is possible during the tool design, which can be exploited to avoid the weakening of the component strength due to formation of wide intermetallic phase seams.
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Yukizawa, Yohei, Shu Takagawa, Shota Higashihira, Emi Kamono, Yutaka Inaba, and Naomi Kobayashi. "EP2.46 Verification of Optimal Location of Shelf Graft for Acetabular Dysplasia Using Finite Element Analysis and Virtual Surgery Model." Journal of Hip Preservation Surgery 12, Supplement_1 (2025): i68—i69. https://doi.org/10.1093/jhps/hnaf011.220.
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Abstract Background: The shelf acetabuloplasty has received renewed attention as a minimally invasive, joint preservation surgery for developmental dysplasia of the hip joint. However, there has been little scientific validation of the optimal location of the shelf in terms of stress reduction. Clinical Questions: (1) Where is the optimal shelf location for successful stress reduction to the acetabulum? (2) Are there any patient characteristics that indicate limitations of shelf acetabuloplasty that make it difficult to obtain load distribution? Patients and Methods: Preoperative computed tomography of fifteen patients scheduled for shelf acetabuloplasty was used for finite element analysis to create various simulated shelf models. The following four parameters were set as the shelf-placement conditions: shelf height, shelf tilting, shelf extrusion, and shelf anterior–lateral position. Three different conditions were set for each parameter, creating a total of 81 shelf models for each case. Using finite element analysis, the mean equivalent stress in the loading area of the acetabulum was analyzed, and the stress reduction ratio was calculated based on the preoperative values. Results: Among the 1,215 shelf models across 15 cases, 284 demonstrated a stress reduction exceeding 10%. Multiple regression analysis showed that the center-edge angle was the only significant factor associated with stress reductio n (p&lt;0.001). The center-edge angles at which the acetabular stress reduction exceeded 10% were limited to approximately 13°–19°. Multivariate analysis using a mixed linear model, while avoiding the influence of the dysplasia grade, revealed that the equivalent stress values on the acetabulum were significantly lower for lateral shelf placement than the anterior position (p&lt;0.05). Moreover, the stress on the inner shelf, the part implanted in the pelvis, was significantly greater in the lateral position than the anterior position (p&lt;0.001) and increased with increase in the tilting angle (p&lt;0.001). The reduction rate of acetabular stress exhibited a significant correlation with the equivalent stress on the inner shelf (p&lt;0.0001). Conclusions: Considering load dispersion, cases with the center-edge angle between 13° and 19° may benefit from shelf acetabuloplasty. Moreover, lateral installation is advantageous for effective load dispersion. Additionally, stress changes in the acetabulum are influenced by the stresses applied to the inner shelf.
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Griffiths, Ross W., and Jonathan H. Fink. "Effects of surface cooling on the spreading of lava flows and domes." Journal of Fluid Mechanics 252 (July 1993): 667–702. http://dx.doi.org/10.1017/s0022112093003933.
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Scaling analyses describe the evolution of an extrusion of viscous or plastic fluid in the presence of surface cooling and solidification, under the assumption that the flows consist of two components: an isothermal interior and a surface crust. The ‘crust’ is a complex thermal and rheological boundary layer which we model using a viscous, plastic or brittle rheology. These models are thought to be relevant to some types of lava flows and address the effects of cooling on their morphology and rate of advance of the flow front. They show that effects of crust strength will dominate over both viscous and yield stresses in the interior when the ratio of crust thickness to flow length exceeds the ratio of effective yield stress of the crust to basal shear stress exerted on the bulk of the flow, a condition that appears likely to be met by many lava flows and small outgrowths on large flows. Similarity solutions are compared with measurements on the spreading of extrusions of wax beneath cold water in the laboratory, where the extruded liquid is viscous but develops a solid crust. Crust strength provides the dominant retarding force for the wax flows in cases where surface solidification occurs rapidly compared with lateral advection. These conditions give flows topped by sheets of solid that buckle or rift apart, or extrusions that enlarge by small bulbous outgrowths (analogous to ‘pillows’ on submarine lavas and ‘toes’ on some sub-aerial basalt flows). A comparison of the models with data for the growth of lava domes in the craters of Mount St Helens and Soufrière of St Vincent volcanoes reveals that spreading of those domes was not controlled by stresses in the flow interior. Instead the data are consistent with a balance between gravity and yield stresses in a thin crustal layer over most of the growth period.
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Guo, Peng, Zhujun Han, Shaopeng Dong, Fan Gao, and Jiani Li. "New Constraints on Slip Behavior of the Jianshui Strike-Slip Fault from Faulted Stream Channel Risers and Airborne Lidar Data, SE Tibetan Plateau, China." Remote Sensing 13, no. 10 (2021): 2019. http://dx.doi.org/10.3390/rs13102019.
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The temporal slip behavior of a fault from displaced landforms when there are no chronological data remains poorly understood. The southern segment of the Xiaojiang fault zone (XJFZ) plays an important role in accommodating the lateral extrusion of the SE Tibetan plateau. However, there are few reports on the evolution of the offset landforms and slip behavior of the fault due to the dense vegetation in the region. Here, offset landforms along the Jianshui fault (JSF) in the southern segment of the XJFZ are systematically interpreted and measured using high-resolution satellite imagery, field investigations, and airborne lidar. The risers on the right banks of three stream channels feature similar left-lateral offset characteristics near the town of Dongshanzhai. The left-lateral offsets consist of multiple inflections produced by seismic events, and the offset of each event is similar. These inflections are distributed downstream in a stair-stepped manner. The newly formed inflections are located close to the fault, and the earlier formed ones are eroded by flowing water and migrate downstream. The difference between the amount of downstream erosion of two adjacent inflections varies. Assuming the stream’s long-term erosion rate remains steady, the estimated time intervals between seismic events are different. Combined with the cumulative offset probability density calculation for 92 offsets, the JSF is considered to show a nonperiodic characteristic earthquake recurrence pattern. We also propose a multistage offset evolution model of the stream channel riser. This provides a new way to analyze the seismic recurrence pattern of the fault over a relative time scale.
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Zhang, Guifang, Chunyan Qu, Xinjian Shan, Xiaogang Song, Yingfeng Zhang, and Yanchuan Li. "Present-Day Crustal Deformation of the Northwestern Tibetan Plateau Based on InSAR Measurements." Remote Sensing 15, no. 21 (2023): 5195. http://dx.doi.org/10.3390/rs15215195.
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In this study, The ENVISAT advanced synthetic aperture radar observations from 2003 to 2010 of a descending track covering an area of 100 km × 300 km were used to map the surface velocity field in northwestern Tibet. The derived line-of-sight (LOS) velocity map revealed that interseismic deformation was mainly located on the Altyn Tagh Fault (ATF) and other four immature subsidiary faults (i.e., Tashikule Fault, Muzitage-jingyuhe Fault, Heishibeihu Fault, and Woniuhu Fault). A 2D elastic screw dislocation model was used to interpret the interferometric synthetic aperture radar (InSAR) velocity profiles, which revealed the following results. (a) The oblique movement is partitioned between left-lateral slip at a rate of 6.3 ± 1.4 mm/y on the ATF and 5.9 ± 2.8 mm/y on the subsidiary faults. The low slip rate of the ATF indicates that the ATF does not drive the northeastward extrusion of material, with most of the extrusion occurring in the eastern interior of the plateau and the four subsidiary faults localizing the oblique convergence partitioned in the west. This can reasonably explain why catastrophic earthquakes and rapid slip do not occur all over along the ATF. (b) Based on the four subsidiary faults accommodating the oblique movement and the traces amalgamation with the EKLF (delineated Bayan Har plate boundary to the northeast), we concluded guardedly that the four subsidiary faults are the evoluting plate boundary of the Bayan Har block to the northwest. (c) The Tanan top-up structure had an uplift rate of ~0.6 mm/y at the south of the Tarim Basin.
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Fujita, K., B. M. Koz'min, K. G. Mackey, S. A. Riegel, M. S. McLean, and V. S. Imaev. "Seismotectonics of the Chersky Seismic Belt, eastern Sakha Republic (Yakutia) and Magadan District, Russia." Stephan Mueller Special Publication Series 4 (September 17, 2009): 117–45. http://dx.doi.org/10.5194/smsps-4-117-2009.
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Abstract. The Chersky seismic belt represents a zone of deformation between the North American and Eurasian plates in northeast Russia. The belt extends from the Laptev Sea into the Chersky Range where it splits into two branches. One branch extends to Kamchatka and the Aleutian-Kurile Junction, while the other branch extends south towards Sakhalin Island. Focal mechanisms indicate a change from extension to transpression in the northern Verkhoyansk Range and generally left-lateral transpression in the Chersky Range extending to northern Kamchatka. The few focal mechanisms on the second branch suggest right-lateral transpression. A large number of faults, sub-parallel to the seismicity and presumed to be strike-slip, are visible in satellite imagery and topographic maps and are also associated with seismically generated landslides. These data support a model in which the Sea of Okhotsk forms the core of a separate Okhotsk microplate surrounded by diffuse boundaries on the north and west. Microseismicity in continental northeast Russia is most heavily concentrated within and between the fault systems along the northern boundary of the proposed Okhotsk plate and indicates a high level of deformation. The sense of slip on the faults (both from focal mechanisms and geology) are also generally consistent with the extrusion of the Okhotsk plate to the southeast as it is compressed between its larger neighbors. The northernmost part of the Okhotsk plate may be decoupled to some degree from the more stable central Sea of Okhotsk.
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Li, S. P., G. Chen, and J. W. Li. "Analysis of crustal deformation and strain characteristics in the Tianshan Mountains with least-squares collocation." Solid Earth Discussions 7, no. 4 (2015): 3179–97. http://dx.doi.org/10.5194/sed-7-3179-2015.
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Abstract. By fitting the observed velocity field of the Tianshan Mountains from 1992 to 2006 with least-squares collocation, we established a velocity field model in this region. The velocity field model reflects the crustal deformation characteristics of the Tianshan reasonably well. From the Tarim Basin to the Junggar Basin and Kazakh platform, the crustal deformation decreases gradually. Divided at 82° E, the convergence rates in the west are obviously higher than those in the east. We also calculated the parameter values for crustal strain in the Tianshan Mountains. The results for maximum shear strain exhibited a concentration of significantly high values at Wuqia and its western regions, and the values reached a maxima of 4.4×10−8 a−1. According to isogram distributions for the surface expansion rate, we found evidence that the Tianshan Mountains have been suffering from strong lateral extrusion by the basin on both sides. Combining this analysis with existing results for focal mechanism solutions from 1976 to 2014, we conclude that it should be easy for a concentration of earthquake events to occur in regions where maximum shear strains accumulate or mutate. For the Tianshan Mountains, the possibility of strong earthquakes in Wuqia–Jiashi and Lake Issyk-Kul will persist over the long term.
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Yu, Sihan, and Xiaoning Su. "A Crustal Deformation Pattern on the Northeastern Margin of the Tibetan Plateau Derived from GPS Observations." Remote Sensing 15, no. 11 (2023): 2905. http://dx.doi.org/10.3390/rs15112905.
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The northeastern margin is a natural experimental field for studying crustal extrusion and expansion mechanisms. The accurate crustal deformation pattern is a key point in the analysis of regional deformation mechanisms and seismic hazard research and judgment. In this paper, the present-day GPS velocity field on the northeastern margin of the Tibetan Plateau was obtained from encrypted GPS observations around the Haiyuan–Liupanshan fault zone, combined with GPS observations on the northeastern margin of the Tibetan Plateau from 2010 to 2020. Firstly, we divided the study area into three relatively independent blocks: the ORDOS block, Alxa block, and Lanzhou block; secondly, the accurate fault distribution of the Haiyuan–Liupanshan fault zone was taken into account to obtain the optimal inversion model; finally, using the block and fault back-slip dislocation model, the inversion obtained the slip rate distribution, locking depth, and slip deficit rate of each fault. The results indicate that the Laohushan Fault and Haiyuan Fault are dominated by the left-lateral strike-slip, while the Liupanshan Fault is dominated by the thrust dip-slip, and the Guguan–Baoji Fault has both left-lateral strike-slip and thrust dip-slip components. The maximum locking depths of the Laohushan Fault, Haiyuan Fault, Liupanshan Fault, and Guguan–Baoji Fault are 5 km, 13 km, 15 km, and 10 km, respectively, and the locking of the Haiyuan Fault is strong in the middle section and weak in the eastern and western section. The Haiyuan Fault is still in the post-earthquake stress adjustment stage. The slip deficit rate decays from 3.6 mm/yr to 1.8 mm/yr from west to east along the fault zone. Combined with geological and historical seismic data, the results suggest that the mid-long-term seismic risk in the Liupanshan Fault is high.
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Flegler, Vanessa Judith, Akiko Rasmussen, Karina Borbil, et al. "Mechanosensitive channel gating by delipidation." Proceedings of the National Academy of Sciences 118, no. 33 (2021): e2107095118. http://dx.doi.org/10.1073/pnas.2107095118.
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The mechanosensitive channel of small conductance (MscS) protects bacteria against hypoosmotic shock. It can sense the tension in the surrounding membrane and releases solutes if the pressure in the cell is getting too high. The membrane contacts MscS at sensor paddles, but lipids also leave the membrane and move along grooves between the paddles to reside as far as 15 Å away from the membrane in hydrophobic pockets. One sensing model suggests that a higher tension pulls lipids from the grooves back to the membrane, which triggers gating. However, it is still unclear to what degree this model accounts for sensing and what contribution the direct interaction of the membrane with the channel has. Here, we show that MscS opens when it is sufficiently delipidated by incubation with the detergent dodecyl-β-maltoside or the branched detergent lauryl maltose neopentyl glycol. After addition of detergent-solubilized lipids, it closes again. These results support the model that lipid extrusion causes gating: Lipids are slowly removed from the grooves and pockets by the incubation with detergent, which triggers opening. Addition of lipids in micelles allows lipids to migrate back into the pockets, which closes the channel even in the absence of a membrane. Based on the distribution of the aliphatic chains in the open and closed conformation, we propose that during gating, lipids leave the complex on the cytosolic leaflet at the height of highest lateral tension, while on the periplasmic side, lipids flow into gaps, which open between transmembrane helices.
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Mahapatra, Shilpa, Smruti Chandan Mohapatra, and Ratna Parameswaran. "A comparative evaluation of pre-treatment and post-treatment outcomes in patients subjected to lower incisor extraction." Journal of Contemporary Orthodontics 8, no. 1 (2024): 36–41. http://dx.doi.org/10.18231/j.jco.2024.006.
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Mandibular incisor crowding is the most frequently occurring characteristic of malocclusion, which can be resolved by removing single lower incisor. The aim of this study was to evaluate and compare the pre- and post-treatment outcomes through model and cephalometric analysis of the patients subjected to single lower incisor extraction. In this retrospective study pre- and post-treatment lateral cephalograms and models of 23 patients who underwent fixed orthodontic treatment with single incisor extraction on lower arch were evaluated. The study subjects were classified into two groups based on extraction pattern (Group I: Upper premolar and lower single incisor extraction; Group II: Upper non extraction and lower single incisor extraction). Both cephalometric and model analysis were carried out using Ilexis FACAD AB-2014 Version3.8.0.0 (Ilexis AB, Sweden). Wilcoxon Signed Rank test was used to compare the pre and post-treatment quantitative parameters. A significant decrease was observed in the maxillary intermolar width, mandibular intercanine width, mandibular intermolar width, mandibular arch length and anterior Bolton’s ratio. Group I subjects revealed a greater decrease in maxillary intermolar width compared to Group II, whereas a greater decrease in mandibular intercanine width, mandibular intermolar width and anterior Bolton’s ratio was documented in Group II subjects compared to Group I. Cephalometric analysis revealed significant proclination and extrusion effect of lower incisors along with protrusive tendency of the lower lip. The findings of the present study provide an additional option of extracting single lower incisor, in borderline or Class II camouflage treatment cases.
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Kalyuzhniy, Volodymyr, Oleksandr Yarmolenko, and Kostyantyn Marchuk. "Stamping a medium – sized cartridge blank from low – carbon steel." Mechanics and Advanced Technologies 5, no. 1 (2021): 113–21. http://dx.doi.org/10.20535/2521-1943.2021.5.1.234466.
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The work is devoted to obtaining a medium – sized cartridge blank from low-carbon steel. The sequence of punching transitions includes a hot back- extrusion operation, two cold draw – thinning operations, and a cold crimp operation. Modeling using the finite element method established: efforts and specific forces during operations, thermal effect during shaping, shape and size of semi – finished products with distributions of strain intensity. An elastoplastic metal model was used, which made it possible to reveal the forces of extracting the tool from deformed semifinished products and the forces of removing semifinished products from the matrix. A hollow semifinished product with the required dimensions of a protrusion on the bottom part from the side of the cavity and a protrusion on the end for forming a flange is obtained by reverse extrusion. The possibility of carrying out the first drawing operation with thinning through three sequentially located matrixes is shown. After this operation, annealing of the semi-finished product is required to restore plasticity. In the second operation of drawing with thinning and additional stamping of the bottom part, the final dimensions of this part from the side of the cavity and the shaping of the flange on the lateral surface of the semi-finished product are provided with the creation of a macrostructure to ensure the required operational properties. The shape and dimensions of the wall of the semi-finished product after the second drawing, the distribution of the intensity of deformations in it are determined from the condition of reaching the final dimensions and mechanical properties of the cartridge blank at the last crimping operation. For this, the deformations obtained as a result of the second drawing are taken into account when modeling the crimp. The proposed technology for stamping a blank of a sleeve can be implemented on a universal press – forging equipment, has a high productivity and minimizes mechanical processing.
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Hadlari, T., and R. H. Rainbird. "Retro-arc extension and continental rifting: a model for the Paleoproterozoic Baker Lake Basin, Nunavut1Geological Survey of Canada Contribution 20100436." Canadian Journal of Earth Sciences 48, no. 8 (2011): 1232–58. http://dx.doi.org/10.1139/e11-002.
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Within Baker Lake sub-basin, the ca. 1.84–1.78 Ga Baker Sequence formed in two stages. At the start of the first stage, during rift initiation, half-graben were host to siliciclastic alluvial, eolian, and lacustrine deposits and to localized felsic minette volcanics. Back-stepping of facies indicate high accommodation rates and areal expansion, which, combined with extrusion of voluminous minette volcanic rocks, are interpreted to record increased extension and rift climax. Low accommodation post-rift deposits from the second stage of basin development are relatively thin and coeval felsite domes spatially restricted. Volcanic rocks and some siliciclastic units correlate between sub-basins, and hence the interpreted history of Baker Lake sub-basin is extended across greater Baker Lake Basin. This implies that the basin formed in response to regional extension and crustal thinning. The Baker Lake Basin marks the northern extent of a series of basins that trend northeastward along the Snowbird Tectonic Zone, including an inlier of the correlative Martin Group in northern Saskatchewan. The high accommodation first stage of basin development is proposed to have been the result of intra-continental retro-arc extension during ca. 1.85–1.84 Ga formation of the Kisseynew back-arc basin of the Trans-Hudson Orogen. Upon closure of the Kisseynew back-arc basin and collision of the Superior Province with the western Churchill Province, Baker Lake Basin was subject to strike-slip faulting. The second, low accommodation stage of basin development and strike-slip faulting is proposed to record lateral tectonic escape between the Saskatchewan–Manitoba and Baffin Island – Committee Bay foci of the western Churchill – Superior Province collision.
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Wang, Lifeng, Shuo Zhang, Shiqiang Li, et al. "Laboratory Test Study on Pile Jacking Penetration Mechanism Considering Different Diameter and Length Based on Photoelectric Integration Technology." Buildings 13, no. 5 (2023): 1247. http://dx.doi.org/10.3390/buildings13051247.
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Model tests are carried out on the jacked single piles of different diameters and pile lengths under the model pile of different diameters and pile lengths in clayey soil, which aims to investigate the penetration mechanical mechanism. How to accurately test the pile end resistance and pile side resistance during jacked pile sinking is particularly important. In this paper, a full-section spoke-type pressure sensor, a double diaphragm temperature self-compensating fiber Bragg grating (FBG) earth pressure sensor and a sensitized miniature FBG strain sensor are jointly applied to a single pile penetration model test to test a single pile driving force, pile end resistance and pile body stress during penetration. The test results show that the load transfer performance of test piles will be affected by different diameters, and the axial force transfer capability of a large diameter in the depth direction is better than that of a small diameter since the compacting effect is more obvious. The unit skin friction of the pile increases gradually as the depth increases, which is larger due to the lateral extrusion force increasing as the diameter increases. At the same depth, the unit skin friction of two different diameter piles demonstrates “friction fatigue”, which also decreases obviously as the depth increases. Under the conditions of this test, the maximum frictional resistance of the pile TP1 pile side is about 27.7% higher than that of the test pile TP2. In the static pile sinking process of three test piles in cohesive soil, 50% is end bearing; therefore, there is 50% friction, and the diameter influences the end bearing and the length influences the friction.
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Kang, Wenjun, Xiwei Xu, Michael E. Oskin, et al. "Characteristic slip distribution and earthquake recurrence along the eastern Altyn Tagh fault revealed by high-resolution topographic data." Geosphere 16, no. 1 (2019): 392–406. http://dx.doi.org/10.1130/ges02116.1.
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Abstract The seismic cycle model is roughly constrained by limited offset data sets from the eastern Altyn Tagh fault with a low slip rate. The recent availability of high-resolution topographic data from the eastern Altyn Tagh fault provides an opportunity to obtain distinctly improved quantitative, dense measurements of fault offsets. In this paper, we used airborne light detection and ranging data and unmanned aircraft vehicle photogrammetry to evaluate fault offsets. To better constrain the large earthquake recurrence model, we acquired dense data sets of fault displacements using the LaDiCaoz_v2.1 software. A total of 321 offset measurements below 30 m highlight two new observations: (1) surface-slip of the most recent earthquake and multiple events exhibit both short-wavelength (m-scale) and long-wavelength (km-scale) variability; and (2) synthesis of offset frequency analysis and coefficient of variation indicate regular slip events with ∼6 m slip increment on fault segments to the west of the Shulehe triple junction. The distribution of offsets and paleoseismological data reveal that the eastern Altyn Tagh fault exhibits characteristic slip behavior, with the characteristic slip of ∼6 m and a recurrence period ranging from 1170 to 3790 years. Paleoearthquake recurrence intervals and slip increments yield mean horizontal slip-rate estimates of 2.1–2.6 mm/yr for fault segments to the west of the Shulehe triple junction. Assuming a 10 km rupture depth and a 30 GPa shear modulus, we estimated a characteristic slip event moment magnitude (Mw) of ∼7.6. Finally, we discuss the interaction mechanism between Altyn Tagh fault (strike fault) and the NW-trending thrust faults (reverse faults) that caused the sudden decrease of sinistral slip rate at the Shulehe and Subei triple junctions; our results support the eastward “lateral slip extrusion” model.
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Wang, Xuezhen, Hao Zhou, and Jiangtao Ji. "Effect of Mounting Angle on Bending Subsoiling Tool–Soil Interactions Using DEM Simulations." Agriculture 12, no. 11 (2022): 1830. http://dx.doi.org/10.3390/agriculture12111830.
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Mechanical subsoiling is an effective practice to promote better water infiltration and crop root development. The bending subsoiling tool (BST) is a primary subsoiling tool and is used to remove soil compaction and restore soil productivity. In this study, a discrete element model was developed and validated using laboratory soil bin tests to investigate the effects of the mounting angle of the BST (5°–33°) on soil disturbance behaviors and draft forces. The results show that the upheaval, failure and fragmentation of soil was achieved by successive shearing, uplifting, extrusion, tension and turning actions from the cutting share and cambered shank of the BST. Increasing soil depths gave smaller soil disturbance ranges in lateral, forward and upward directions. With an increase in mounting angle, both the draft force and soil rupture distance ratio initially decreased and then increased, whereas the soil loosening efficiency initially increased and then decreased. Overall, increasing the mounting angle of the BST from 5° to 33° gave a greater soil surface flatness that increased rapidly when the mounting angle increased from 26° to 33°. Appropriately increasing mounting angle of the BST from 5° to 26° could lift more moist soil from the deep seed and middle layers (5.0–15.5% increase) into the shallow seed layer (depth of <50 mm) without seriously affecting the mixing of the deep layer and other layers. Considering both the soil disturbance characteristics and draft forces, a mounting angle of 26° appeared to outperform the other angles.
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Pounds, G., A. Liu, A. Jones, and L. Jennings. "DEVELOPMENT OF A PRE-CLINICAL EXPERIMENTAL MODEL TO MEASURE MEDIAL MENISCUS POSITION DURING A SIMULATED GAIT CYCLE OF THE KNEE JOINT." Orthopaedic Proceedings 105-B, SUPP_9 (2023): 59. http://dx.doi.org/10.1302/1358-992x.2023.9.059.
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The aim of this work was to develop a novel, accessible and low-cost method, which is sufficient to measure changes in meniscal position in a whole-knee joint model performing dynamic motion in a knee simulator.An optical tracking method using motion markers, MATLAB (MATLAB, The MathWorks Inc.) and a miniature camera system (Raspberry Pi, UK) was developed. Method feasibility was assessed on porcine whole joint knee samples (n = 4) dissected and cemented to be used in the simulator (1). Markers were placed on three regions (medial, posterior, anterior) of the medial meniscus with corresponding reference markers on the tibial plateau, so the relative meniscal position could be calculated. The Leeds high kinematics gait profile scaled to the parameters of a pig (1, 2) was driven in displacement control at 0.5 Hz. Videos were recorded at cycle-3 and cycle-50. Conditions tested were the capsule retained (intact), capsule removed and a medial posterior root tear. Mean relative displacement values were taken at time-points relating to the peaks of the axial force and flexion-extension gait inputs, as well as the range between the maximum and minimum values. A one-way ANOVA followed by Tukey post hoc analysis were used to assess differences (p = 0.05).The method was able to measure relative meniscal displacement for all three meniscal regions. The medial region showed the greatest difference between the conditions. A significant increase (p < 0.05) for the root tear condition was found at 0.28s and 0.90s (axial load peaks) during cycle-3. Mean relative displacement for the root tear condition decreased by 0.29 mm between cycle-3 and cycle-50 at the 0.28s time-point. No statistically significant differences were found when ranges were compared at cycle-3 and cycle-50.The method was sensitive to measure a substantial difference in medial-lateral relative displacement between an intact and a torn state. Meniscus extrusion was detected for the root tear condition throughout test duration. Further work will progress onto human specimens and apply an intervention condition.
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Kiss, Dániel, Thibault Duretz, and Stefan Markus Schmalholz. "Tectonic inheritance controls nappe detachment, transport and stacking in the Helvetic nappe system, Switzerland: insights from thermomechanical simulations." Solid Earth 11, no. 2 (2020): 287–305. http://dx.doi.org/10.5194/se-11-287-2020.
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Abstract. Tectonic nappes have been investigated for more than a hundred years. Although geological studies often refer to a “nappe theory”, the physical mechanisms of nappe formation are still disputed. We apply two-dimensional numerical simulations of shortening of a passive margin to investigate the thermomechanical processes of detachment (or shearing off), transport and stacking of nappes. We use a visco-elasto-plastic model with standard creep flow laws, Drucker–Prager and von Mises yield criteria. We consider tectonic inheritance with two initial mechanical heterogeneities: (1) lateral heterogeneity of the basement–cover interface due to half-grabens and horsts and (2) vertical heterogeneities due to layering of mechanically strong and weak sedimentary units. The model shows detachment and horizontal transport of a thrust nappe that gets stacked on a fold nappe. The detachment of the thrust sheet is triggered by stress concentrations around the sediment–basement contact and the resulting brittle–plastic shear band that shears off the sedimentary units from the sediment–basement contact. Horizontal transport is facilitated by a basal shear zone just above the basement–cover contact, composed of thin, weak sediments that act as a décollement. Fold nappe formation occurs by a dominantly ductile closure of a half-graben and the associated extrusion of the half-graben fill. We apply our model to the Helvetic nappe system in western Switzerland, which is characterized by stacking of the Wildhorn thrust nappe above the Morcles fold nappe. The modeled structures, the deformation rates and the temperature field agree with data from the Helvetic nappe system. Mechanical heterogeneities must locally generate effective viscosity (i.e., ratio of stress to viscoplastic strain rate) contrast of about 3 orders of magnitude to model nappe structures similar to the ones of the Helvetic nappe system. Our results indicate that the structural evolution of the Helvetic nappe system was controlled by tectonic inheritance and that material softening mechanisms are not essential to reproduce the first-order nappe structures.
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Wang, Min, Fan Wang, Xin Jiang, et al. "GPS determined coseismic slip of the 2021 Mw7.4 Maduo, China, earthquake and its tectonic implication." Geophysical Journal International 228, no. 3 (2021): 2048–55. http://dx.doi.org/10.1093/gji/ggab460.
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SUMMARY The 2021 Mw7.4 Maduo earthquake occurred on the Jiangcuo fault within the Bayan Har block in eastern Tibet. It is a rather unique event and attests that large earthquakes can occur in the interior of major tectonic blocks within the Tibetan plateau. By processing GPS data observed in the eastern Tibet region, we produce a data set documenting 3-D coseismic displacements of the Maduo earthquake. Using the data set to constrain a coseismic slip model, we find that the earthquake ruptured a nearly vertical fault about 170 km in length, with ∼90% of the moment released in the shallow layer above 20 km depth. The maximum slip of ∼3.6 m occurred near the surface around a bend in the east segment of the fault. The overall seismic moment release is 1.82 × 1020 N m and is equivalent to Mw7.4. Driven by the eastward extrusion of the Tibetan plateau, the deformation field in eastern Tibet is dominated by left-lateral shear, with the strikes of the tectonic faults rotating clockwise from west to east along with the shear stress orientation. This deformation pattern explains the mechanisms of earthquakes along block boundary faults, as well as the ones on faults within the blocks. The Jiangcuo fault is located ∼70 km south of the East Kunlun fault and could be connected to the Kunlun Mountain Pass fault to its WNW that ruptured during the 2001 Kokoxili earthquake, and a seismic gap of ∼240 km long between the two faults is worth special attention for its increased earthquake potential.
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Vanaclocha, Amparo, Vicente Vanaclocha, Carlos M. Atienza, et al. "Nucleus Disc Replacement: Design and Material Selection FEA Analysis." Advances in Materials Science and Engineering 2022 (October 31, 2022): 1–14. http://dx.doi.org/10.1155/2022/5040747.
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Study Design. We selected the materials and implant design and performed Finite Element Analysis (FEA) studies. Background. Nucleus disc replacements, implanted since 1960, have undergone continuous evolution in materials and designs, but subsidence, extrusion, and in vivo degradation limit widespread use. Aim. The aim of this study is to create a new nucleus disc replacement that avoids the abovementioned drawbacks. Material and Methods. We created eighteen designs with varied materials and analyzed them with FEA in compression and shear tests in a lumbar spine model programmed in Ansys Parametric Design Language. Results. Bionate® 80A had the closest mechanical characteristics to the intact disc nucleus. Monobloc designs bore physiological stresses correctly but suffered significant deformations with permanent damage during surgical insertion through the annulus opening. In addition, sandwich designs were too rigid and had an unreliable curing process. Therefore, we chose an oval doughnut-like 5 mm wall monobloc Bionate® 80A nucleus replacement. It minimized implant stress in loading, distributed loads uniformly, and tolerated lateral compression during implantation. Conclusions. Out of the eighteen designs we analyzed with FEA, we found that the monobloc oval doughnut-like Bionate 80A nucleus replacement reproduced best the biomechanics of the natural disc nucleus and had the lowest subsidence risk as it transmits the load to the ring apophysis. Furthermore, implanting it through the annulotomy required to perform a lumbar microdiscectomy should be possible due to its elasticity. Furthermore, due to its elasticity implanting it through the average annulotomy required to perform a lumbar microdiscectomy should be possible.
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Kim, Yeji, Chanyoung Song, Gyuseon Song, Sol Bi Kim, Hyun-Wook Han, and Inbo Han. "Using Natural Language Processing to Identify Low Back Pain in Imaging Reports." Applied Sciences 12, no. 24 (2022): 12521. http://dx.doi.org/10.3390/app122412521.
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A natural language processing (NLP) pipeline was developed to identify lumbar spine imaging findings associated with low back pain (LBP) in X-radiation (X-ray), computed tomography (CT), and magnetic resonance imaging (MRI) reports. A total of 18,640 report datasets were randomly sampled (stratified by imaging modality) to obtain a balanced sample of 300 X-ray, 300 CT, and 300 MRI reports. A total of 23 radiologic findings potentially related to LBP were defined, and their presence was extracted from radiologic reports. In developing NLP pipelines, section and sentence segmentation from the radiology reports was performed using a rule-based method, including regular expression with negation detection. Datasets were randomly split into 80% for development and 20% for testing to evaluate the model’s extraction performance. The performance of the NLP pipeline was evaluated by using recall, precision, accuracy, and the F1 score. In evaluating NLP model performances, four parameters—recall, precision, accuracy, and F1 score—were greater than 0.9 for all 23 radiologic findings. These four scores were 1.0 for 10 radiologic findings (listhesis, annular fissure, disc bulge, disc extrusion, disc protrusion, endplate edema or Type 1 Modic change, lateral recess stenosis, Schmorl’s node, osteophyte, and any stenosis). In the seven potentially clinically important radiologic findings, the F1 score ranged from 0.9882 to 1.0. In this study, a rule-based NLP system identifying 23 findings related to LBP from X-ray, CT, and MRI reports was developed, and it presented good performance in regards to the four scoring parameters.
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Abdallah, Yomna K., and Alberto T. Estévez. "Biowelding 3D-Printed Biodigital Brick of Seashell-Based Biocomposite by Pleurotus ostreatus Mycelium." Biomimetics 8, no. 6 (2023): 504. http://dx.doi.org/10.3390/biomimetics8060504.
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Mycelium biocomposites are eco-friendly, cheap, easy to produce, and have competitive mechanical properties. However, their integration in the built environment as durable and long-lasting materials is not solved yet. Similarly, biocomposites from recycled food waste such as seashells have been gaining increasing interest recently, thanks to their sustainable impact and richness in calcium carbonate and chitin. The current study tests the mycelium binding effect to bioweld a seashell biocomposite 3D-printed brick. The novelty of this study is the combination of mycelium and a non-agro–based substrate, which is seashells. As well as testing the binding capacity of mycelium in welding the lattice curvilinear form of the V3 linear Brick model (V3-LBM). Thus, the V3-LBM is 3D printed in three separate profiles, each composed of five layers of 1 mm/layer thickness, using seashell biocomposite by paste extrusion and testing it for biowelding with Pleurotus ostreatus mycelium to offer a sustainable, ecofriendly, biomineralized brick. The biowelding process investigated the penetration and binding capacity of the mycelium between every two 3D-printed profiles. A cellulose-based culture medium was used to catalyse the mycelium growth. The mycelium biowelding capacity was investigated by SEM microscopy and EDX chemical analysis of three samples from the side corner (S), middle (M), and lateral (L) zones of the biowelded brick. The results revealed that the best biowelding effect was recorded at the corner and lateral zones of the brick. The SEM images exhibited the penetration and the bridging effect achieved by the dense mycelium. The EDX revealed the high concentrations of carbon, oxygen, and calcium at all the analyzed points on the SEM images from all three samples. An inverted relationship between carbon and oxygen as well as sodium and potassium concentrations were also detected, implying the active metabolic interaction between the fungal hyphae and the seashell-based biocomposite. Finally, the results of the SEM-EDX analysis were applied to design favorable tessellation and staking methods for the V3-LBM from the seashell–mycelium composite to deliver enhanced biowelding effect along the Z axis and the XY axis with <1 mm tessellation and staking tolerance.
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Li, Jun, Xuben Wang, Qingyan Qin, Gang Zhang, Dahu Li, and Jun Zhou. "Deep physical structure and geotectonic implications of the eastern margin of the Qinghai–Tibet Plateau." Earth Sciences Research Journal 20, no. 4 (2016): 1. http://dx.doi.org/10.15446/esrj.v20n4.61632.
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The eastern margin of the Qinghai–Tibet Plateau (QTP) is the focus of studies on eastward lateral extrusion of the latter’s crustal material. This study aims to explore the structural response of the QTP’s eastern crust–mantle to the extrusion, and the basis for the latter’s geological structure. Data on long-period magnetotelluric sounding of cross-tectonic units and Bouguer gravity were used to determine the physical structure of the crust–mantle at the plateau’s eastern margin. The findings are as follows: (i) the apparent density structure indicates extensive presence of a low-density material in the middle–lower crusts of the Songpan and Sichuan–Yunnan blocks at the QTP’s eastern margin. On the other hand, the Yangtze cratonic block (Sichuan Basin) contains a material with a significantly higher density. To the west of the Longmenshan–Panxi tectonic zones, and along the lower crust at 40–50 km depth, is an obvious low-density zone aligned in a northeast–southwest orientation; (ii) the electrical structural model spanning Songpan block–Longmenshan tectonic zone–Yangtze block reveals three distinct electrical structural units along the cross-section bounded by the Longmenshan tectonic zone. The first is the Songpan block, which has high and low resistivity at the shallow layer and middle–lower crusts, respectively. Next is the Yangtze craton, which has low and relatively higher resistivity at the shallow layer and middle–lower crusts, respectively. Third is the Longmenshan transitional tectonic zone, whose shallow layer and deep structure are characterized by an electrical structure with a thrust nappe towards the east, and a high-conductivity material extending to the lithospheric mantle, respectively; (iii) the apparent density and electrical structures indicate that the Panxi tectonic zone has a weakened structure in the lower crust; and (iv) physical properties of the QTP’s deep structure indicate that its eastern margin may contain a middle–lower crustal fluid material with the attributes of high conductivity and low density. Its distribution is closely related to the uplift mechanism and deep seismogenic activities at the QTP’s eastern margin. Estructura profunda e implicaciones geotectónicas del margen oriental del altiplano Qinghai-Tíbet ResumenEl margen oriental del altiplano Qinghai-Tíbet (QTP, del inglés Qinghai-Tibet Plateau) es el área de la extrusión lateral hacia el Este de material cortical. Este trabajo se enfoca en explorar la respuesta estructural de las capas superiores en el altiplano y las bases para su estructuración geológica. Se utilizó información magnetotelúrica y anomalías de Bouguer para determinar la respuesta geofísica de las capas superiores en el margen occidental del altiplano. Dentro de los principales resultados se tiene: (i) la distribución de la densidad aparente indica la presencia de material de baja densidad en las capas medias y bajas de los bloques Songpan y Sichuan-Yunnan en el Este del QTP. Por otro lado, el bloque cratónico Yangtze (en la cuenca Sichuan) contiene material con una mayor densidad. Al oeste de las zonas tectónicas Longmeshan-Panxi, y a lo largo de las capas inferiores, entre 40 y 50 kilómetros de profundidad, hay una zona de baja densidad con orientación noreste-suroeste. (ii) El modelo eléctrico que abarca el bloque Songpan, la zona tectónica Longmeshan y el bloque Yangtze, revela tres unidades a lo largo de la sección cruzada subordinada a la zona tectónica Longmenshan. La primera unidad está en el bloque Songpan, con alta resistividad en la capa superficial y baja en las capas media e inferiores. Luego aparece el cratón Yangtze, con baja resistividad en la superficie y resistividad media en las capas media e inferiores. La tercera unidad es la zona tectónica transicional de Longmenshan, cuya estructura superficial y profunda está caracterizada por una estructura eléctrica asociada a una falla de cabalgamiento hacia el Este y alta conductividad de material que se extiende hacia el manto litosférico. (iii) La densidad aparente y las estructuras eléctricas indican que la zona tectónica de Panxi está debilitada en las capas inferiores. (iv) las propiedades geofísicas de la estructura profunda del altiplano Qinghai-Tíbet muestran que su margen oriental puede contener un fluido de material en las capas bajas y medias con características de alta conductividad y baja densidad. Su distribución está interrelacionada con el mecanismo de elevación y las actividades sismogénicas profundas en el margen oriental del altiplano.
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Choe, Robert, Eoin Devoy, Blake Kuzemchak, et al. "Computational investigation of interface printing patterns within 3D printed multilayered scaffolds for osteochondral tissue engineering." Biofabrication 14, no. 2 (2022): 025015. http://dx.doi.org/10.1088/1758-5090/ac5220.
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Abstract Osteoarthritis is a highly prevalent rheumatic musculoskeletal disorder that commonly affects many joints. Repetitive joint overloading perpetuates the damage to the affected cartilage, which undermines the structural integrity of the osteochondral unit. Various tissue engineering strategies have been employed to design multiphasic osteochondral scaffolds that recapitulate layer-specific biomechanical properties, but the inability to fully satisfy mechanical demands within the joint has limited their success. Through computational modeling and extrusion-based bioprinting, we attempted to fabricate a biphasic osteochondral scaffold with improved shear properties and a mechanically strong interface. A 3D stationary solid mechanics model was developed to simulate the effect of lateral shear force on various thermoplastic polymer/hydrogel scaffolds with a patterned interface. Additionally, interfacial shear tests were performed on bioprinted polycaprolactone (PCL)/hydrogel interface scaffolds. The first simulation showed that the PCL/gelatin methacrylate (GelMA) and PCL/polyethylene glycol diacrylate (PEGDA) scaffolds interlocking hydrogel and PCL at interface in a 1:1 ratio possessed the largest average tensile (PCL/GelMA: 80.52 kPa; PCL/PEGDA: 79.75 kPa) and compressive stress (PCL/GelMA: 74.71 kPa; PCL/PEGDA: 73.83 kPa). Although there were significant differences in shear strength between PCL/GelMA and PCL/PEGDA scaffolds, no significant difference was observed among the treatment groups within both scaffold types. Lastly, the hypothetical simulations of potential biphasic 3D printed scaffolds showed that for every order of magnitude decrease in Young’s modulus (E) of the soft bioink, all the scaffolds underwent an exponential increase in average displacement at the cartilage and interface layers. The following work provides valuable insights into the biomechanics of 3D printed osteochondral scaffolds, which will help inform future scaffold designs for enhanced regenerative outcomes.
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Vosgerau, Henrik, Pierpaolo Guarnieri, Rikke Weibel, et al. "Sedimentology and reservoir architecture of a widespread siliciclastic intra-lava unit, Kangerlussuaq, East Greenland." Journal of Sedimentary Research 91, no. 6 (2021): 662–82. http://dx.doi.org/10.2110/jsr.2021.02.
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ABSTRACT The Rosebank hydrocarbon discovery in 2004 proved that intra-lava sandstones form attractive reservoirs in the Faroe–Shetland Basin and the new volcanic play triggered the need for suitable analogues to describe and assess sedimentology, reservoir architecture, compartmentalization, and connectivity of intra-lava siliciclastic units. The onshore Kangerlussuaq Basin in East Greenland offers the opportunity to study Paleogene intra-lava siliciclastic sandstones and their interaction with lavas, on the scale of the Rosebank Field. The focus of this study is a siliciclastic-dominated intra-lava unit, 4–10 m thick, exposed in almost vertical cliff sections over distances of several kilometers. The unit reflects a short return to siliciclastic deposition following initiation of volcanic activity and extrusion of the first lava flows in the area. Deposition took place as shoreface and delta progradation in a marine-influenced, shallow embayment. Lateral variations in sedimentary facies distribution and geometry are prominent and were largely governed by an interplay of base-level variations and autocyclic processes, the surface roughness and type of substratum on which deposition took place, and differential block movements before and during deposition. Presence of local topographic barriers are of key importance and influenced the lava–sediment interaction and the resulting 3D-geometry of lava flows and sediment bodies. In addition, compartmentalization of the intra-lava sandstone unit is observed and is controlled by the offset across normal faults, intersecting dikes, and to a lesser extent by invasive and eroding lavas. A depositional model is suggested that incorporates the detailed sedimentological and 3D photogrammetric observations and presents a possible explanation for the contrasting architecture of the intra-lava unit observed in three areas located a few kilometers apart. The model embraces the complex interplay between siliciclastic and volcanic settings and reveals important aspects to consider when recoverable volumes of hydrocarbons are estimated in intra-volcanic subsurface reservoirs in volcanic rifted margins with poor seismic imaging of the relatively thin intra-lava reservoirs.
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Weimin, Gao, Li Xiangdong, and Bai Yuxing. "An assessment of late fixed functional treatment and the stability of Forsus appliance effects." Australasian Orthodontic Journal 30, no. 1 (2014): 2–10. http://dx.doi.org/10.2478/aoj-2014-0001.
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Abstract Objective: To evaluate the treatment effects and stability of Forsus appliance therapy. Methods: Thirty-one patients (15 males, 16 females) with a mean age of 15.8 ± 3.1 years (range 13 to 17.6 years, 15.3 ± 1.2 years for females and 16.5 ± 1.6 years for males) were selected. All patients had passed beyond their pubertal growth phase (after CS4 or MP3cap). Lateral cephalograms and three-dimensional (3D) models were analysed before treatment (T0), at the end of treatment (T1) and at a follow-up visit (T2). The mean period from T1 to T2 was 25 months and ranged from 17 to 32 months. Tooth position and angulations, together with maxillary and mandibular position, were measured on cephalograms. The inclinations and vertical distance changes of mandibular incisors were measured on a 3D digital model. Results: The Forsus appliance produced significant skeletal and dental changes during treatment (from T0 to T1). In the sagittal plane, mandibular length (Co-Gn) increased 6.47 mm, the maxillary incisors and molars uprighted (∠U1-SN decreased 8.97° and ∠U6-SN decreased 3.51°), the mandibular incisors proclined (∠L1-MP increased 3.93°) and the mandibular molars advanced (L6-SP increased 3.61 mm). In the vertical plane, the maxilla and mandible rotated clockwise (∠PP-SN, ∠MP-SN, ∠OP-SN increased significantly) and the mandibular molars extruded (L6-MP increased 3.06 mm). All of the changes remained relatively stable after treatment. Cephalometric sagittal and vertical changes affecting the mandibular incisors from T1 to T2 were statistically insignificant (p > 0.05) except for lower incisor extrusion (L1-MP, p < 0.05). Conclusion: The Forsus appliance induced significant skeletal and dental changes, which remained relatively stable during the observation period. The mandibular incisors, in particular, were stable two years after treatment.
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Zhang, Xueying, Xiang-Hua Deng, Zhe Song, et al. "Matrix Metalloproteinase Inhibition With Doxycycline Affects the Progression of Posttraumatic Osteoarthritis After Anterior Cruciate Ligament Rupture: Evaluation in a New Nonsurgical Murine ACL Rupture Model." American Journal of Sports Medicine 48, no. 1 (2019): 143–52. http://dx.doi.org/10.1177/0363546519887158.
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Background: Doxycycline has broad-spectrum activity as a matrix metalloproteinase (MMP) inhibitor and thus could reduce the progression of posttraumatic osteoarthritis (PTOA) after anterior cruciate ligament (ACL) rupture. Hypothesis: Doxycycline would inhibit progression of PTOA in a murine ACL rupture model. Study Design: Controlled laboratory study. Methods: For the in vitro study, cadaveric C57BL/6 male mice knees (N = 108) were used for the development of a nonsurgical ACL rupture model. For the in vivo study, 24 C57BL/6 male mice then underwent ACL rupture with our manual procedure and were divided into 4 groups: untreated control; doxycycline, 10 mg/kg/d; doxycycline, 50 mg/kg/d; and doxycycline, 100 mg/kg/d. Doxycycline was administered in drinking water beginning immediately after ACL rupture. Radiographic imaging and paw prints were evaluated at 3, 7, 14, and 28 days. The foot length and toe spread were analyzed as measures of function. Histology and MMP-13 immunohistochemistry were done at 4 weeks. Results: Radiographs demonstrated anterior tibial subluxation and meniscal extrusion after ACL rupture, confirming knee joint instability without fractures. Statistically significant differences in gait were found between the intact and experimental groups. Histologic examination demonstrated cartilage damage, meniscal tears, and mild osteoarthritis after ACL rupture, similar to what occurs in human patients. Hypertrophy of the posterior horn of the medial and lateral meniscus was found, and tears of the posterior horn of the menisci were common. All doxycycline groups had a lower score than the untreated control group, indicating less cartilage damage. The posterior tibia of the untreated group had the most cartilage damage as compared with the 3 doxycycline groups, with a significant difference between the untreated and 50-mg/kg/d doxycycline groups, suggesting that the latter dose may protect against proteoglycan loss and decrease the progression of osteoarthritis. The nondoxycycline group had the highest synovial inflammation score among all groups, indicating that doxycycline has an inhibitory effect on synovitis. There was significantly lower MMP-13 expression on the tibia in the doxycycline-treated groups, with a positive correlation between doxycycline concentration and MMP-13 inhibition. Conclusion: Modulation of MMP-13 activity by doxycycline treatment may offer a novel biological pathway to decrease the progression of PTOA after ACL rupture. Clinical Relevance: Doxycycline is an approved, readily available drug with infrequent side effects of photosensitivity and gastrointestinal symptoms. Future clinical trials could evaluate doxycycline to reduce or prevent progressive cartilage damage after ACL rupture.
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Wan, Zhihui, Heng Liu, Feng Zhou, and Guoliang Dai. "Axial Bearing Mechanism of Post-Grouted Piles in Calcareous Sand." Applied Sciences 12, no. 5 (2022): 2731. http://dx.doi.org/10.3390/app12052731.
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Post-grouted piles, as a foundation form for large-span and large-scale structures on calcareous sand, are expected to provide a high bearing capacity, but research on the response of post-grouted piles subjected to axial load in calcareous sand is still in the exploratory stage. In this paper, a model test is constructed for static pressure piles in calcareous sand under axial loading. The response of axial compressive piles, with and without post-grouting, in calcareous sand were investigated, and the test results were compared with those of axial compressive piles, with and without post-grouting, in siliceous sand. The influence of post-side-grouting on the response of a single pile subjected to axial compressive load in calcareous sand and its bearing mechanism were further analyzed. The results show that the change in shaft resistance, caused by the lateral extrusion of calcareous sand, is less than the negative effect caused by particle breakage during pile driving, so single piles without post-grouting in calcareous sand exhibit weaker axial bearing behavior than that in siliceous sand. A single pile with post-side-grouting in calcareous sand can provide a higher bearing capacity by increasing the shaft resistance and tip resistance compared with a single pile without post-side-grouting, and the increased ratio of the bearing capacity of piles, after grouting in calcareous sand, is better than that of piles in siliceous sand. Post-side-grouting can not only strengthen the surrounding soil by the solidification effect of injected cement grout, but it can also have a strengthening effect on the tip resistance. In addition, ideal-geometry grouting has more obvious advantages in improving the bearing behavior of pile foundations than annular point grouting, and higher stability in improving the bearing properties of pile foundations is evident for ideal-geometry grouting. Therefore, it is suggested that a directional grouting device should be adopted in actual projects in the future to form a more stable pile-soil interaction system and to expand the application prospect of pile foundations in calcareous sand.
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Paffrath, Marcel, Wolfgang Friederich, Stefan M. Schmid, and Mark R. Handy. "Imaging structure and geometry of slabs in the greater Alpine area – a P-wave travel-time tomography using AlpArray Seismic Network data." Solid Earth 12, no. 11 (2021): 2671–702. http://dx.doi.org/10.5194/se-12-2671-2021.
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Abstract. We perform a teleseismic P-wave travel-time tomography to examine the geometry and structure of subducted lithosphere in the upper mantle beneath the Alpine orogen. The tomography is based on waveforms recorded at over 600 temporary and permanent broadband stations of the dense AlpArray Seismic Network deployed by 24 different European institutions in the greater Alpine region, reaching from the Massif Central to the Pannonian Basin and from the Po Plain to the river Main. Teleseismic travel times and travel-time residuals of direct teleseismic P waves from 331 teleseismic events of magnitude 5.5 and higher recorded between 2015 and 2019 by the AlpArray Seismic Network are extracted from the recorded waveforms using a combination of automatic picking, beamforming and cross-correlation. The resulting database contains over 162 000 highly accurate absolute P-wave travel times and travel-time residuals. For tomographic inversion, we define a model domain encompassing the entire Alpine region down to a depth of 600 km. Predictions of travel times are computed in a hybrid way applying a fast TauP method outside the model domain and continuing the wave fronts into the model domain using a fast marching method. We iteratively invert demeaned travel-time residuals for P-wave velocities in the model domain using a regular discretization with an average lateral spacing of about 25 km and a vertical spacing of 15 km. The inversion is regularized towards an initial model constructed from a 3D a priori model of the crust and uppermost mantle and a 1D standard earth model beneath. The resulting model provides a detailed image of slab configuration beneath the Alpine and Apenninic orogens. Major features are a partly overturned Adriatic slab beneath the Apennines reaching down to 400 km depth still attached in its northern part to the crust but exhibiting detachment towards the southeast. A fast anomaly beneath the western Alps indicates a short western Alpine slab whose easternmost end is located at about 100 km depth beneath the Penninic front. Further to the east and following the arcuate shape of the western Periadriatic Fault System, a deep-reaching coherent fast anomaly with complex internal structure generally dipping to the SE down to about 400 km suggests a slab of European origin limited to the east by the Giudicarie fault in the upper 200 km but extending beyond this fault at greater depths. In its eastern part it is detached from overlying lithosphere. Further to the east, well-separated in the upper 200 km from the slab beneath the central Alps but merging with it below, another deep-reaching, nearly vertically dipping high-velocity anomaly suggests the existence of a slab beneath the eastern Alps of presumably the same origin which is completely detached from the orogenic root. Our image of this slab does not require a polarity switch because of its nearly vertical dip and full detachment from the overlying lithosphere. Fast anomalies beneath the Dinarides are weak and concentrated to the northernmost part and shallow depths. Low-velocity regions surrounding the fast anomalies beneath the Alps to the west and northwest follow the same dipping trend as the overlying fast ones, indicating a kinematically coherent thick subducting lithosphere in this region. Alternatively, these regions may signify the presence of seismic anisotropy with a horizontal fast axis parallel to the Alpine belt due to asthenospheric flow around the Alpine slabs. In contrast, low-velocity anomalies to the east suggest asthenospheric upwelling presumably driven by retreat of the Carpathian slab and extrusion of eastern Alpine lithosphere towards the east while low velocities to the south are presumably evidence of asthenospheric upwelling and mantle hydration due to their position above the European slab.