Determination of layer-specific mechanical properties of human coronary arteries with nonatherosclerotic intimal thickening and related constitutive modeling

2005 ◽  
Vol 289 (5) ◽  
pp. H2048-H2058 ◽  
Author(s):  
Gerhard A. Holzapfel ◽  
Gerhard Sommer ◽  
Christian T. Gasser ◽  
Peter Regitnig
Keyword(s):  
Mechanical Properties ◽  
Coronary Arteries ◽  
Wall Thickness ◽  
Tissue Type ◽  
Outer Diameter ◽  
Intimal Thickening ◽  
Mechanical Heterogeneity ◽  
Tensile Stresses ◽  
The Media ◽  
The Individual

At autopsy, 13 nonstenotic human left anterior descending coronary arteries [71.5 ± 7.3 (mean ± SD) yr old] were harvested, and related anamnesis was documented. Preconditioned prepared strips ( n = 78) of segments from the midregion of the left anterior descending coronary artery from the individual layers in axial and circumferential directions were subjected to cyclic quasi-static uniaxial tension tests, and ultimate tensile stresses and stretches were documented. The ratio of outer diameter to total wall thickness was 0.189 ± 0.014; ratios of adventitia, media, and intima thickness to total wall thickness were 0.4 ± 0.03, 0.36 ± 0.03, and 0.27 ± 0.02, respectively; axial in situ stretch of 1.044 ± 0.06 decreased with age. Stress-stretch responses for the individual tissues showed pronounced mechanical heterogeneity. The intima is the stiffest layer over the whole deformation domain, whereas the media in the longitudinal direction is the softest. All specimens exhibited small hysteresis and anisotropic and strong nonlinear behavior in both loading directions. The media and intima showed similar ultimate tensile stresses, which are on average three times smaller than ultimate tensile stresses in the adventitia (1,430 ± 604 kPa circumferential and 1,300 ± 692 kPa longitudinal). The ultimate tensile stretches are similar for all tissue layers. A recently proposed constitutive model was extended and used to represent the deformation behavior for each tissue type over the entire loading range. The study showed the need to model nonstenotic human coronary arteries with nonatherosclerotic intimal thickening as a composite structure composed of three solid mechanically relevant layers with different mechanical properties. The intima showed significant thickness, load-bearing capacity, and mechanical strength compared with the media and adventitia.

scholarly journals Intimal thickening and disruption of the media occur in the arterial walls of coronary arteries not associated with coronary arterial aneurysms in patients with Kawasaki disease

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Tomoya Tsuchihashi ◽  
Nobuyuki Kakimoto ◽  
Takashi Takeuchi ◽  
Tomohiro Suenaga ◽  
Takayuki Suzuki ◽  
...  
Keyword(s):  
Kawasaki Disease ◽  
Acute Phase ◽  
Coronary Arteries ◽  
Structural Changes ◽  
Artery Aneurysm ◽  
Intimal Thickening ◽  
Structure Damage ◽  
Convalescent Phase ◽  
Arterial Structure ◽  
The Media

Abstract Background Coronary artery aneurysm (CAA) is an important complication of Kawasaki disease (KD) that is associated with arterial structure damage. However, few studies have examined structural changes in coronary arteries that are not associated with CAA. Methods We examined coronary arteries in KD patients with CAAs who underwent follow-up coronary angiography (CAG) and optical coherence tomography (OCT). Coronary arterial branches with no abnormal findings during the most recent CAG were classified into two groups. Arteries with an acute-phase CAA that later regressed were classified as group R; arteries with no abnormal findings on either acute or convalescent phase CAG were classified as group N. Coronary arterial wall structural changes were compared between groups using OCT. Results Fifty-seven coronary arterial branches in 23 patients were evaluated by OCT. Thirty-six branches showed no abnormality during the most recent CAG. Both groups R and N comprised 18 branches. Maximum intimal thicknesses in groups R and N were 475 and 355 µm, respectively (p = 0.007). The incidences of media disruption were 100% and 67%, respectively (p = 0.02). Calcification, macrophage accumulation, and thrombus were not found in either group. Conclusions Intimal thickening and disruption of the media occur in coronary arteries with acute phase CAAs that later regress in the convalescent phase, as well as in arteries with normal CAG findings in the acute and convalescent phases.

Full Well Corrosion Insight – Case Studies in the Added Value of Electromagnetic Thickness Measurements During Well Interventions

2021 ◽  
Author(s):  
Andrew Imrie ◽  
Maciej Kozlowski ◽  
Omar Torky ◽  
Aditya Arie Wijaya
Keyword(s):  
Case Studies ◽  
Wall Thickness ◽  
Added Value ◽  
Metal Loss ◽  
Outer Diameter ◽  
Metal Thickness ◽  
True Condition ◽  
Pass Through ◽  
External Corrosion ◽  
The Individual

AbstractMonitoring pipe corrosion is one of the critical aspects in the well intervention. Such analysis is used to evaluate and justify any remedial actions, to prolong the longevity of the well. Typical corrosion evaluation methods of tubulars consist of multifinger caliper tools that provide high-resolution measurements of the internal condition of the pipe. Routinely, this data is then analyzed and interpreted with respect to the manufacture's nominal specification for each tubular. However, this requires assumptions on the outer diameter of the tubular may add uncertainty, and incorrectly calculate the true metal thicknesses. This paper will highlight cases where the integration of such tool and electromagnetic (EM) thickness data adds value in discovering the true condition of both the first tubular and outer casings.These case studies demonstrate the use of a multireceiver, multitransmitter electromagnetic (EM) metal thickness tool operating at multiple simultaneous frequencies. It is used to measure the individual wall thickness across multiple strings (up to five) and operates continuously, making measurements in the frequency domain. This tool was combined with a multifinger caliper to provide a complete and efficient single-trip diagnosis of the tubing and casing integrity. The combination of multifinger caliper and EM metal thickness tool results gives both internal and external corrosion as well as metal thickness of first and outer tubular strings.The paper highlights multiple case studies including; i) successfully detecting several areas of metal loss (up to greater than 32%) on the outer string, which correlated to areas of the mobile salt formation, ii) overlapping defects in two tubulars and, iii) cases where a multifinger caliper alone doesn't provide an accurate indication of the true wall thickness. The final case highlights the advantages of integrating multiple tubular integrity tools when determining the condition of the casing wall.Metal thickness tools operating on EM principles benefit from a slim outer diameter design that allows the tools to pass through restrictions which typically would prevent ultrasonic scanning thickness tools. Additionally, EM tools are unaffected by the type of fluid in the wellbore and not affected by any non-ferrous scale buildup that may present in the inside of the tubular wall. Combinability between complementary multifinger caliper technology and EM thickness results in two independent sensors to provide a complete assessment of the well architecture.

The Production of High Density Cast Iron Tubes by Horizontally Continuous Casting

2012 ◽  
Vol 527 ◽  
pp. 3-8
Author(s):  
Stasys Bockus
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Chemical Composition ◽  
Continuous Casting ◽  
Wall Thickness ◽  
Casting Process ◽  
New Technique ◽  
Outer Diameter ◽  
Continuous Casting Process ◽  
A New Technique

In this paper, a new technique to produce cast iron tubes used for liners of auto engines has been developed and examined. The tubes with an outer diameter of 90 mm and a wall thickness of 14 mm were produced massively by horizontally continuous casting. There are the values of casting parameters and constructions of crystallizers recommended for the continuous casting process of cast iron tubes in our paper. The metallographic microstructure, chemical composition and the mechanical properties of the tubes were investigated. The results of our investigations were successfully used for producing cast iron tubes suitable for liners of auto engines.

scholarly journals Intimal Thickening and Disruption of The Media Occur in The Arterial Walls of Coronary Arteries Not Associated With Coronary Arterial Aneurysms in Patients With Kawasaki Disease

2021 ◽  
Author(s):  
Tomoya Tsuchihashi ◽  
Nobuyuki Kakimoto ◽  
Takashi Takeuchi ◽  
Tomohiro Suenaga ◽  
Takayuki Suzuki ◽  
...  
Keyword(s):  
Kawasaki Disease ◽  
Acute Phase ◽  
Coronary Arteries ◽  
Structural Changes ◽  
Artery Aneurysm ◽  
Intimal Thickening ◽  
Structure Damage ◽  
Convalescent Phase ◽  
Arterial Structure ◽  
The Media

Abstract Background Coronary artery aneurysm (CAA) is an important complication of Kawasaki disease (KD) that is associated with arterial structure damage. However, few studies have examined structural changes in coronary arteries not associated with CAA.Methods We examined coronary arteries in KD patients with CAAs who underwent follow-up coronary angiography (CAG) and optical coherence tomography (OCT). Coronary arterial branches with no abnormal findings on most recent CAG were classified into two groups. Arteries with an acute-phase CAA that later regressed were classified as group R and arteries with no abnormal findings on either acute or convalescent phase CAG were classified as group N. Coronary arterial wall structural changes were compared between groups using OCT.ResultsFifty-seven coronary arterial branches in 23 patients were evaluated by OCT. Thirty-six branches showed no abnormality on most recent CAG. Both groups R and N comprised 18 branches. Maximum intimal thickness in groups R and N was 475 and 355 µm, respectively (p = 0.007). The incidence of disruption of the media was 100% and 67%, respectively (p = 0.02). Calcification, macrophage accumulation, and thrombus were not found in either group.ConclusionsIntimal thickening and disruption of the media occur not only in coronary arteries with acute phase CAAs that later regress in the convalescent phase, but also in arteries with normal CAG findings in the acute and convalescent phases.

DYNAMIC AND COMPETENCE ASPECTS OF THE MEDIA EDUCATIONAL CONCEPT OF DEVELOPING A PERSON’S READINESS FOR LIFELONG SELF-EDUCATION

2019 ◽  
pp. 23-33
Author(s):  
S. V. Akmanova ◽  
L. V. Kurzaeva ◽  
N. A. Kopylova
Keyword(s):  
Informal Education ◽  
Great Influence ◽  
Formal Training ◽  
Life Stages ◽  
Media Technologies ◽  
Educational Concept ◽  
The Media ◽  
The Individual ◽  
Competence Models ◽  
Scientific Achievements

The harmonious existence of the individual in the modern informational era, which is overly saturated with rapidly developing media technologies, is almost impossible without the developed readiness of the individual for lifelong continuous self-education. The formation and development of this readiness can begin during the formal training at the stage of higher education of the person and continue during informal education throughout his future life. Stages of socialization and professionalization of the person have a great influence on the level nature of this readiness. Based on scientific achievements in the field of self-education of university students, national and world media education, we developed dynamic and competence models of media educational concept of developing a person’s readiness for lifelong self-education. The concept demonstrates interconnection of these two models, as well as consistency with the previously developed normative model of developing this readiness.

MEDIA SOCIALIZATION OF PERSONALITY IN THE CONTEXT OF INMUTATION IN THE MASS MEDIA

2021 ◽  
pp. 104-109
Author(s):  
Chernysh O.O.
Keyword(s):  
Mass Media ◽  
Negative Impact ◽  
Effective Interaction ◽  
Individual Characteristics ◽  
Media Culture ◽  
Active Growth ◽  
Media Space ◽  
The Media ◽  
The Individual

The urgency of the researched problem is connected with the growing role of mass media in modern conditions leads to change of values and transformation of identity of the person. The active growth of the role of the media, their influence on the formation and development of personality leads to the concept of “media socialization” and immutation in the media. The aim of the study is to outline the possibilities of the process of media socialization in the context of immutation in the media. The methods of our research are: analysis of pedagogical, psychological, literature, synthesis, comparison, generalization. The article analyzes the views of domestic and foreign scientists on the problem of immutation in the media and the transformation of the information space. In the context of the mass nature of the immutation of society, the concept of “media socialization” becomes relevant, which is the basis for reducing the negative impact of the media on the individual.The author identifies the lack of a thorough study of the concept of “media socialization” in modern scientific thought. Thus, media socialization is associated with the transformation of traditional means of socialization, and is to assimilate and reproduce the social experience of mankind with the help of new media.The article analyzes the essence of the concepts “media space”, “mass media” and “immutation”. The influence of mass media on the formation and development of the modern personality is described in detail.The study concluded that it is necessary to form a media culture of the individual, to establish safe and effective interaction of young people with the modern media system, the formation of media awareness, media literacy and media competence in accordance with age and individual characteristics for successful media socialization. The role of state bodies in solving the problem of media socialization of the individual was also determined. It is determined that the process of formation of media culture in youth should take place at the level of traditional institutions of socialization of the individual.The author sees the prospect of further research in a detailed analysis and study of the potential of educational institutions as an institution and a means of counteracting the mass nature of the immutation of society.Key words: immutation, media socialization, mass media, media space, information.

scholarly journals Towards Manufacturing of Ultrafine-Laminated Structures in Metallic Tubes by Accumulative Extrusion Bonding

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 389
Author(s):  
Matthew R. Standley ◽  
Marko Knezevic
Keyword(s):  
Solid State ◽  
Wall Thickness ◽  
Complex Geometry ◽  
Tube Wall ◽  
Film Theory ◽  
Radial Strain ◽  
Surface Preparation ◽  
Grain Structure ◽  
Outer Diameter ◽  
Laminated Structures

A severe plastic deformation process, termed accumulative extrusion bonding (AEB), is conceived to steady-state bond metals in the form of multilayered tubes. It is shown that AEB can facilitate bonding of metals in their solid-state, like the process of accumulative roll bonding (ARB). The AEB steps involve iterative extrusion, cutting, expanding, restacking, and annealing. As the process is iterated, the laminated structure layer thicknesses decrease within the tube wall, while the tube wall thickness and outer diameter remain constant. Multilayered bimetallic tubes with approximately 2 mm wall thickness and 25.25 mm outer diameter of copper-aluminum are produced at 52% radial strain per extrusion pass to contain eight layers. Furthermore, tubes of copper-copper are produced at 52% and 68% strain to contain two layers. The amount of bonding at the metal-to-metal interfaces and grain structure are measured using optical microscopy. After detailed examination, only the copper-copper bimetal deformed to 68% strain is found bonded. The yield strength of the copper-copper tube extruded at 68% improves from 83 MPa to 481 MPa; a 480% increase. Surface preparation, as described by the thin film theory, and the amount of deformation imposed per extrusion pass are identified and discussed as key contributors to enact successful metal-to-metal bonding at the interface. Unlike in ARB, bonding in AEB does not occur at ~50% strain revealing the significant role of more complex geometry of tubes relative to sheets in solid-state bonding.

scholarly journals Characterization of Mechanical Heterogeneity in Dissimilar Metal Welded Joints

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4145
Author(s):  
He Xue ◽  
Zheng Wang ◽  
Shuai Wang ◽  
Jinxuan He ◽  
Hongliang Yang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Welded Joints ◽  
Structural Integrity ◽  
Material Interfaces ◽  
Mechanical Heterogeneity ◽  
Finite Element Software ◽  
Dissimilar Metal ◽  
Stress Changes

Dissimilar metal welded joints (DMWJs) possess significant localized mechanical heterogeneity. Using finite element software ABAQUS with the User-defined Material (UMAT) subroutine, this study proposed a constitutive equation that may be used to express the heterogeneous mechanical properties of the heat-affected and fusion zones at the interfaces in DMWJs. By eliminating sudden stress changes at the material interfaces, the proposed approach provides a more realistic and accurate characterization of the mechanical heterogeneity in the local regions of DMWJs than existing methods. As such, the proposed approach enables the structural integrity of DMWJs to be analyzed in greater detail.

P3588The synergistic effect of NIRS-detected lipid-rich plaque and 5 different multidirectional wall shear stress metrics on human coronary plaque growth

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
E M J Hartman ◽  
A M Kok ◽  
A Hoogendoorn ◽  
F J H Gijsen ◽  
A F W Steen ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Synergistic Effect ◽  
Coronary Arteries ◽  
Wall Thickness ◽  
Plaque Progression ◽  
Lipid Rich Plaque ◽  
Plaque Growth ◽  
Wall Shear ◽  
The Impact

Abstract Introduction Local wall shear stress (WSS) metrics, high local lipid levels (as detected by near-infrared spectroscopy (NIRS)), as well as systemic lipid levels, have been individually associated with atherosclerotic disease progression. However, a possible synergistic effect remains to be elucidated. This study is the first study to combine WSS metrics with NIRS-detected local lipid content to investigate a potential synergistic effect on plaque progression in human coronary arteries. Methods The IMPACT study is a prospective, single centre study investigating the relation between atherosclerotic plaque progression and WSS in human coronary arteries. Patients with ACS treated with PCI were included. At baseline and after 1-year follow-up, patients underwent near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) imaging and intravascular doppler flow measurements of at least one non-culprit coronary artery. After one month, a CT angiography was made. CT derived centreline combined with IVUS lumen contours resulted in a 3D reconstruction of the vessel. The following WSS metrics were computed using computational fluid dynamics applying the vessel specific invasive flow measurements: time-average wall shear stress (TAWSS), relative residence time (RRT), cross-flow index, oscillatory shear index and transverse wall shear stress. Low TAWSS is known as pro atherogenic, in contrast to all the other shear stress metrics, at which a high magnitude is pro-atherogenic. The arteries were divided into 1.5mm/45° sectors. Based on NIRS-IVUS, wall thickness change over time was determined and NIRS positive sectors detected. Furthermore, per vessel the shear stress was divided into tertiles (low, intermediate, high). To investigate the synergistic effect of local lipids on shear stress related plaque growth, wall thickness change over time was related to the different shear stress metrics comparing the NIRS-positive with the NIRS-negative sectors. Results 15 non-culprit coronary arteries from the first 14 patients were analyzed (age 62±10 years old and 92.9% male). A total of 2219 sectors were studied (5.2%, N=130, NIRS-positive) for wall thickness changes. After studying all five shear stress metrics, we found for TAWSS and RRT that presence of lipids, as detected by NIRS, amplified the effect of shear stress on plaque progression (see figure). Sectors presenting with lipid-rich plaque, compared to NIRS-negative sectors, showed more progression when they were exposed to low TAWSS (p=0.07) or high RRT (p=0.012) and more regression in sectors exposed to high TAWSS (p=0.10) or low RRT (p=0.06). Delta wall thickness vs shear stress Conclusion We presented the first preliminary results of the IMPACT study, showing the synergistic effect of lipid rich plaque and shear stress on plaque progression. Therefore, intravascular lipid-rich plaque (NIRS) assessment has added value to shear stress profiling for the prediction of plaque growth, leading to improved risk stratification. Acknowledgement/Funding ERC starting grant 310457

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