In mathematical-physical models of blood vessels, the "zero-stress state" of the vessel wall is usually defined with reference to the atmospheric pressure (pa approximately 750 mmHg = 100 kPa). Due to this conventional choice, axial and circumferential stresses generated by the (positive) transmural pressure over the radial wall depth can only be positive (in absence of residual stresses) and thus, by definition, only tensile. If the zero-stress state were defined "unconventionally" with reference to vacuum pressure (= 0 mm Hg), the isotropic compressive stress--pa generated by the atmospheric pressure everywhere in the wall would, however, be included in the stress values, and negative (= compressive) stresses would become formally possible. Since materials submitted only to compressions do not need to have the same resistive properties as materials which may also experience tractions, the question whether axial stress (and perhaps also circumferential stress) might be permanently compressive in vessels under physiologic conditions may therefore be important for investigations of the relationship between wall stresses on one side and wall structures, vessel growth, vessel damages, or vessel adaptation processes on the other side. In the present study, radial, circumferential, and axial wall stresses were calculated conventionally and "unconventionally" for three representative "vessel examples." The results clearly suggest that axial wall stress might well be compressive in many vessels. Furthermore, relative differences between conventional and unconventional stress values are quite considerable, and ratios between stresses calculated in the same manner appear to be strongly dependent on the chosen zero-stress state definition.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1118/1.1543148 | DOI Listing |
Med Oral Patol Oral Cir Bucal
January 2025
Bezmialem Vakif University Faculty of Dentistry Department of Oral and Maxillofacial Surgery Fatih, Istanbul, Turkey
Background: The study aimed to investigate the effect of customized lateral nasal wall osteotomy (LNO) on the lateral nasal wall (LNW) and pterygomaxillary junction (PMJ) separation during Le Fort I. We hypothesized that customized LNO on the LNW affect the PMJ separation type.
Material And Methods: This prospective, controlled, randomized study included forty-three patients were randomly assigned to either the conventional or customized (study) osteotomy groups.
Biomimetics (Basel)
December 2024
Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun 130022, China.
Slender tubes are in high demand owing to their lightweight and outstanding energy absorption. However, conventional slender tubes are prone to catastrophic failures such as Euler's buckling under axial load. Interestingly, growing bamboos overcome this similar dilemma via a unique tapered intine in the internodes, which endows them with excellent energy absorption.
View Article and Find Full Text PDFJ Biol Phys
January 2025
The Islamia University of Bahawalpur, Bahawalpur, Pakistan.
The present article focuses on the analysis of the two-phase flow of blood via a stenosed artery under the influence of a pulsatile pressure gradient. The core and plasma regions of flow are modeled using the constitutive relations of Herschel-Bulkley and the Newtonian fluids, respectively. The problem is modeled in a cylindrical coordinate system.
View Article and Find Full Text PDFJ Thorac Dis
December 2024
College of Chemistry and Life Science, Beijing University of Technology, Beijing, China.
Background: Left ventricular assist device (LVAD) has been widely used as an alternative treatment for heart failure, however, aortic regurgitation is a common complication in patients with LVAD support. And the O-A angle (the angle between LVAD outflow graft and the aorta) is considered as a vital factor associated with the function of aortic valve. To date, the biomechanical effect of the O-A angle on the aortic valve remains largely unknown.
View Article and Find Full Text PDFSci Rep
January 2025
School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang, 471000, China.
Geopolymer concrete (GC) is green and environmentally friendly. In order to comprehensively study the mechanical properties and influence mechanism of geopolymer concrete-filled steel tubular (GCFST) columns under various working conditions, this study takes the strength grade of geopolymer concrete, length-diameter ratio and wall thickness of steel tube as design parameters. Eight GCFST columns are designed and the compressive performances are conducted under repeated axial compression.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!