scholarly journals Determination of the mechanical properties of the different layers of blood vessels in vivo.

1995 ◽  
Vol 92 (6) ◽  
pp. 2169-2173 ◽  
Author(s):  
Y. C. Fung ◽  
S. Q. Liu
Keyword(s):  
Mechanical Properties ◽  
Blood Vessels

scholarly journals Numerical Model for the Determination of Erythrocyte Mechanical Properties and Wall Shear Stress in vivo From Intravital Microscopy

2020 ◽  
Vol 10 ◽  
Author(s):  
Vivek P. Jani ◽  
Alfredo Lucas ◽  
Vinay P. Jani ◽  
Carlos Munoz ◽  
Alexander T. Williams ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Stress ◽  
Numerical Model ◽  
Wall Shear Stress ◽  
Intravital Microscopy ◽  
Wall Shear

Remodeling of the Constitutive Equation While a Blood Vessel Remodels Itself Under Stress

1993 ◽  
Vol 115 (4B) ◽  
pp. 453-459 ◽  
Author(s):  
Y. C. Fung ◽  
S. Q. Liu ◽  
J. B. Zhou
Keyword(s):  
Mechanical Properties ◽  
Blood Vessel ◽  
Blood Vessels ◽  
Vessel Wall ◽  
Elastic Strain Energy ◽  
Growth Stress ◽  
Elastic Behavior ◽  
Stress Strain

Changes in the mechanical properties of a blood vessel when it remodels itself under stress are reviewed. One of the recent findings about blood vessels is the rapidity of tissue remodeling when the blood pressure is changed. When the tissue structure and material composition remodel, the zero-stress state of the vessel changes. The mechanical properties change also in the remodeling process. If the elastic behavior is expressed in terms of a pseudo-elastic strain-energy function, then the constants in the function will change in the course of the remodeling. With all these changes taking place, the scope of constitutive equations broadens: it should now include a mass-and-structure growth-stress relationship as well as a stress-strain-relationship. To obtain the mass-and-structure growth-stress relationship, one must be able to determine the mechanical properties of the different layers of the vessel wall, as well as the chemical composition and morphology. For the blood vessels, new methods of mechanical testing must be introduced. A key thought is to use bending of the blood vessel wall. By bending, different layers of the vessel wall are subjected to different stresses, leading to equations that can be used to solve the inverse problem of determining the stress-strain law from measured stress and strain. In vitro and in vivo experiments and theoretical prospectives are presented.

scholarly journals Noninvasive determination of bone mechanical properties using vibration response: A refined model and validation in vivo

1996 ◽  
Vol 29 (1) ◽  
pp. 91-98 ◽  
Author(s):  
S.G. Roberts ◽  
T.M. Hutchinson ◽  
S.B. Arnaud ◽  
B.J. Kiratli ◽  
R.B. Martin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vibration Response ◽  
Refined Model ◽  
Bone Mechanical Properties

Research on elastic recoil and restoration of vessel pulsatility of Zn-Cu biodegradable coronary stents

2020 ◽  
Vol 65 (2) ◽  
pp. 219-227 ◽  
Author(s):  
Chao Zhou ◽  
Xiangyi Feng ◽  
Zhangzhi Shi ◽  
Caixia Song ◽  
Xiaoshan Cui ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Blood Vessels ◽  
316L Stainless Steel ◽  
Coronary Stents ◽  
Metal Stents ◽  
Elastic Recoil ◽  
Vessel Segment ◽  
Biodegradable Metal

AbstractCoronary stents made of zinc (Zn)-0.8 copper (Cu) (in wt%) alloy were developed as biodegradable metal stents (Zn-Cu stents) in this study. The mechanical properties of the Zn-Cu stents and the possible gain effects were characterized by in vitro and in vivo experiments compared with 316L stainless steel stents (316L stents). Young’s modulus of the as-extruded Zn-0.8Cu alloy and properties of the stents, including their intrinsic elastic recoil, stent trackability were evaluated compared with 316L stents. In vivo study was also conducted to evaluate restoration of pulsatility of vessel segment implanted stents. Both Zn-Cu stents and 316L stents have good acute lumen gain. By comparison, the advantages of Zn-Cu stents are as follows: (I) Zn-Cu stents have less intrinsic elastic recoil than 316L stents; (II) stent trackability indicates that Zn-Cu stents have a smaller push force when passing through curved blood vessels, which may cause less mechanical stimulation to blood vessels; (III) in vivo study suggests that Zn-Cu stents implantation better facilitates the recovery of vascular pulsatility.

Using Indentation and Intra-Vascular Ultrasound to Measure Arterial Response

2000 ◽  
Vol 662 ◽  
Author(s):  
P.M. Anderson ◽  
E.N. Glaser ◽  
A.I. Veress ◽  
G.M. Pharr ◽  
D.G. Vince ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Contact Point ◽  
Accurate Determination ◽  
Initial Contact ◽  
Vascular Ultrasound ◽  
Internal Dissipation ◽  
Microindentation Technique ◽  
Micro Indentation

AbstractTwo alternatives to standard tensile testing of arteries are discussed. The first involves inflation of arteries and simultaneous measurement of radial displacement with intra-vascular ultrasound (IVUS). The second involves the measurement of load versus displacement during micro-indentation of the intimal surface. The IVUS technique is used to study the nonlinear stiffening of porcine coronaries during inflation and, ultimately, it may provide a method to determine mechanical properties in vivo. Processing of the IVUS data relies on accurate determination of the luminal/intimal and medial/advential boundaries during inflation. The microindentation technique is used to study the effect of loading rate on tissue stiffness, recovery, and internal dissipation. Ultimately, this technique may provide a method to measure local mechanical properties in the vicinity of an atherosclerotic plaque, for example. Accurate determination of the initial contact point between the indenter and intima is required, however. The techniques appear to successfully capture significant, nonlinear, time-dependent properties of arterial tissue.

A Molecular Approach to Immunoscintigraphy: A Study of the T-Antigen Conformation on the Surface of Tumors

1987 ◽  
Vol 26 (01) ◽  
pp. 1-6 ◽  
Author(s):  
S. Selvaraj ◽  
M. R. Suresh ◽  
G. McLean ◽  
D. Willans ◽  
C. Turner ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Tumor Cell ◽  
T Antigen ◽  
Human Carcinomas ◽  
Animal Tumor ◽  
Synthetic Antigens

The role of glycoconjugates in tumor cell differentiation has been well documented. We have examined the expression of the two anomers of the Thomsen-Friedenreich antigen on the surface of human, canine and murine tumor cell membranes both in vitro and in vivo. This has been accomplished through the synthesis of the disaccharide terminal residues in both a and ß configuration. Both entities were used to generate murine monoclonal antibodies which recognized the carbohydrate determinants. The determination of fine specificities of these antibodies was effected by means of cellular uptake, immunohistopathology and immunoscintigraphy. Examination of pathological specimens of human and canine tumor tissue indicated that the expressed antigen was in the β configuration. More than 89% of all human carcinomas tested expressed the antigen in the above anomeric form. The combination of synthetic antigens and monoclonal antibodies raised specifically against them provide us with invaluable tools for the study of tumor marker expression in humans and their respective animal tumor models.

Storage of Human Blood Platelets

1974 ◽  
Vol 32 (02/03) ◽  
pp. 405-416 ◽  
Author(s):  
M. R Hardeman ◽  
Carina J L. Heynens
Keyword(s):  
Storage Temperature ◽  
Platelet Rich Plasma ◽  
Blood Platelets ◽  
Storage Period ◽  
Serotonin Uptake ◽  
Hypotonic Shock ◽  
Glycolytic Intermediates

SummaryStorage experiments were performed at 4°, 25° and 37° C with platelet-rich plasma under sterile conditions. In some experiments also the effect of storing platelets at 4° C in whole blood was investigated.Before, during and after three days of storage, the platelets were tested at 37° C for their serotonin uptake and response to hypotonic shock. In addition some glycolytic intermediates were determined.A fair correlation was noticed between the serotonin uptake and hypotonic shock experiments. Both parameters were best maintained at 25° C. Also platelet counting, performed after the storage period, indicated 25° C as the best storage temperature. Determination of glycolytic intermediates did not justify any conclusion regarding the optimal storage temperature. Of the various anticoagulants studied, ACD and heparin gave the best results as to the serotonin uptake and hypotonic shock response, either with fresh or stored platelets. The use of EDTA resulted in the lowest activity, especially after storage.The results of these storage experiments in vitro, correspond well with those in vivo reported in the literature.

Basic set of experiments for determination of mechanical properties of sand

2014 ◽  
Vol 62 (1) ◽  
pp. 129-137
Author(s):  
A. Sawicki ◽  
J. Mierczyński
Keyword(s):  
Mechanical Properties ◽  
Soil Mechanics ◽  
Physical And Mechanical Properties ◽  
Local Strain ◽  
Initial State ◽  
Laboratory Equipment ◽  
Additional Information ◽  
Basic Set ◽  
Initial Anisotropy

Abstract A basic set of experiments for the determination of mechanical properties of sands is described. This includes the determination of basic physical and mechanical properties, as conventionally applied in soil mechanics, as well as some additional experiments, which provide further information on mechanical properties of granular soils. These additional experiments allow for determination of steady state and instability lines, stress-strain relations for isotropic loading and pure shearing, and simple cyclic shearing tests. Unconventional oedometric experiments are also presented. Necessary laboratory equipment is described, which includes a triaxial apparatus equipped with local strain gauges, an oedometer capable of measuring lateral stresses and a simple cyclic shearing apparatus. The above experiments provide additional information on soil’s properties, which is useful in studying the following phenomena: pre-failure deformations of sand including cyclic loading compaction, pore-pressure generation and liquefaction, both static and caused by cyclic loadings, the effect of sand initial anisotropy and various instabilities. An important feature of the experiments described is that they make it possible to determine the initial state of sand, defined as either contractive or dilative. Experimental results for the “Gdynia” model sand are shown.

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