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Purpose: Endoscopy is a common and effective method to treat digestive system diseases. Not only can it detect the physiological state of the digestive tract, but also can conduct clinical operations. As a result, it's of great significance to make clear the relationship between the clinical operation and the complications.
Methods: Considering the difficulty in measuring the contact force and determining the stress distribution in real time during endoscopy, a specific-patient finite element model for the frictional behavior at the endoscope-esophagus interface was built in current study. By collecting the CT data of the patient, a 3D esophagus model was built and divided into three characteristic regions (narrow region, thoracic region and abdominal region) according to the physiological structure.
Results: Results showed that the radius of the narrowest position was the dominant factor for the maximum von Mises stress when the endoscope passed through the narrow region. For abdominal region and thoracic region, with the increasing coefficient of friction (COF) and amplitude, the total force duo to frictional force (CFSM), frictional dissipation (FD), strain energy (SE) and maximum von Mises stress (Max) all increased correspondingly. Meanwhile, the region of stress concentration gradually approached the initial contact stage.
Conclusions: The results can provide theoretical basis and technical support for clinical application and offer some suggestions for medical workers during endoscopy as well.
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J Biomech Eng
September 2025
Texas Tech University Box 41021 Lubbock, TX 79409.
Wrist biomechanics remain incompletely understood due to the complexity of experimental measurements in this multi-bone joint system. Finite element analysis provides a powerful alternative for investigating internal variables such as carpal kinematics and displacement patterns. This technical brief compares two bone representation approaches, all-cortical versus cortical-trabecular, using two distinct finite element models developed from the same wrist CT dataset.
View Article and Find Full Text PDFComput Methods Biomech Biomed Engin
September 2025
College of Information Science and Technology, Donghua University, Shanghai, China.
High cost of clinical trials hinders further enhancement of comprehensive mechanical properties of bioresorbable scaffolds (BRS). Therefore, a multi-objective optimization method combining surrogate modeling and finite element simulation is proposed, based on the evaluation of stents with various auxetic structures and materials. The results demonstrated that re-entrant hexagon stent made of PLA (PLA-RH stent) was a more ideal candidate, with superior radial recoil and force.
View Article and Find Full Text PDFRev Sci Instrum
September 2025
Department of Earth Sciences, University College London, London, United Kingdom.
We have developed a new true triaxial apparatus for rock deformation, featuring six servo-controlled loading rams capable of applying maximum stresses of 220 MPa along the two horizontal axes and 400 MPa along the vertical axis to cubic rock samples of 50 mm side. Samples are introduced into a steel vessel, allowing rock specimens to be subjected to confining pressures of up to 60 MPa. Pore fluid lines connected to two pump intensifiers enable high-precision permeability measurements along all three principal stress directions.
View Article and Find Full Text PDFAnal Chem
September 2025
National Key Laboratory of Laser Spatial Information, Harbin Institute of Technology, Harbin 150001, China.
In this paper, a single-quartz-enhanced photoacoustic-photothermal dual spectroscopy sensor based on a spherical acoustic resonator (SAR) is reported for the first time. The dual spectroscopy of quartz-enhanced photoacoustic spectroscopy (QEPAS) and quartz-enhanced photothermal spectroscopy (QEPTS), utilizing a single quartz tuning fork (QTF), eliminates the frequency mismatch issue that occurs when multiple QTFs are used. The dual spectroscopy model was constructed using the finite element method, which provides numerical simulation support for subsequent experiments.
View Article and Find Full Text PDFJ Refract Surg
September 2025
From National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China.
Purpose: To use parametric numerical simulation to characterize and compare the differences in corneal biomechanical responses to laser in situ keratomileusis (LASIK) and keratorefractive lenticule extraction (KLEx) under various surgical settings.
Methods: The Finite Element Model was used in a parametric study to evaluate corneal biomechanical responses to LASIK and KLEx, considering variations in preoperative corneal thickness, corneal flap/cap thickness and diameter, refractive correction, and optical zone diameter. Surgery-induced stress, displacement, and interface contact pressure were compared between LASIK and KLEx using the Wilcoxon signed-rank test.