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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 420 (1983), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biomedical microdevices 2 (1999), S. 151-157 
    ISSN: 1572-8781
    Keywords: tensile test ; collagen fiber ; mechanical property ; patellar tendon ; biomechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Tensile properties of collagen fibers of approximately 1 μm in diameter were determined using a newly developed micro tensile test system for cells and fine fibrous biological tissues. The test system consists of a thermostatic test chamber, an inverted microscope, micromanipulators, a direct drive linear actuator, a cantilever-type load cell, and a video dimension analyzer (VDA). The fibers were isolated with a mechanical method from collagen fascicles (approximately 300 μm in diameter) cut out from the rabbit patellar tendon. The ends of each fiber were attached to the tips of a pair of glass microtubes (15 to 20 μm in outer diameter) using a cyanoacrylate adhesive. One of the microtubes was attached to the load cell; the other one was connected to the linear actuator which was utilized to stretch the fiber. Load applied to the fiber was measured with the load cell, while its elongation was determined with the VDA using the images of the edges of the adhesive as markers. Tangent modulus, tensile strength, and strain at failure of the tested fibers were 54.3± 25.1 MPa, 8.5± 2.6 MPa, and 21.6± 3.0%, respectively. These values were much different from those of collagen fascicles (300 μm in diameter) cut out from the rabbit patellar tendon and also from those of the bulk patellar tendon (Trans. ASME, J. Biomech. Eng. 121, 124–294, 1999); for example, tensile strength and strain at failure of the fibers were approximately 50 and 200% of those of the fascicles, respectively. These results suggest that the mechanical interactions between fibers and between fibers and ground substances contribute much to the mechanical properties of collagen fascicles and bulk tendons.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Annals of biomedical engineering 27 (1999), S. 459-468 
    ISSN: 1573-9686
    Keywords: Vascular mechanics ; Active stress ; Residual strain ; Myogenic response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract To study the effects of smooth muscle contraction and relaxation on the strain and stress distribution in the vascular wall, a mathematical model was proposed. The artery was assumed to be a thick-walled orthotropic tube made of nonlinear, incompressible elastic material. Considering that the contraction of smooth muscle generates an active circumferential stress in the wall, a numerical study was performed using data available in the literature. The results obtained showed that smooth muscle contraction affects the residual strains which exist in a ring segment cut out from the artery and exposed to no external load. When the ring specimen is cut radially, it springs open with an opening angle. The predicted monotonic increase of the opening angle with increasing muscular tone was in agreement with recent experimental results reported in the literature. It was shown that basal muscular tone, which exists under physiological conditions, reduces the strain gradient in the arterial wall and yields a near uniform stress distribution. During temporary changes in blood pressure, the increase in muscular tone induced by elevated pressure tends to restore the distribution of circumferential strain in the arterial wall, and to maintain the flow-induced wall shear stress to normal level. © 1999 Biomedical Engineering Society. PAC99: 8719Rr, 8719Ff, 8710+e
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Effects of compliance mismatch at end-to-end artery/graft anastomoses on the distributions of wall stresses and compliance were studied using the finite element method. The canine common carotid artery (CCA), and expanded polytetrafluoro-ethylene (EPTFE) thin-walled graft, and a newly developed polyurethane graft (HS-2) were used as the models for the host artery, stiff graft, and compliant graft, respectively. Mechanical properties of CCA and HS-2 were determined from a pressure-diameter test, those of EPTFE graft were obtained by tensile test. Nonlinear elasticity of CCA and HS-2 was incorporated by iterating a linear FEM analysis: elastic moduli of the vessel walls were changed every 5 mmHg. The results showed that, in the case of the artery/EPTFE anastomosis in which the diameters of the artery and the graft were matched at 0 mmHg, regions of high tensile and shear stresses appeared in the graft near the anastomosis at the intraluminal pressure of 100 mmHg. The stress concentrations were remarkable, even if the diameters were matched at 100 mmHg and the pressure was varied within a physiological range (60-140 mmHg). Moreover, a hypercompliant zone appeared in the arterial wall near the anastomosis in this case. On the other hand, neither high stress concentrations nor hypercompliant zone appeared near the artery/HS-2 anastomosis. Because the mechanical complications at the compliance-mismatched anastomosis might finally result in graft failure and occlusion, it is important to match the compliance of graft to that of natural arteries, particularly to improve the patency of small-calibered arterial grafts. © 1994 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 179-193 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: As a series of studies on the mechanical properties of materials used in cardiac prostheses, static and dynamic characteristics and stability of five kinds of elastomeric polymers have been studied by uniaxial tensile and fatigue tests in air at room temperature and in saline solution at 37°C. Of all materials tested in this study, Texin MD85A, a segmented polyether polyurethane, has the lowest flexibility under static and dynamic conditions, with relatively high strength. Hexsyn, a polyolefin rubber, is highly flexible with little stress relaxation. However, this material has very low tensile strength and short elongation, and shows unstable change in the elastic modulus during cyclic deformation. Avcothane 51, a copolymer of polyurethane and silicon, has unstable mechanical properties and gradually stiffens upon cyclic deformation. On the other hand, Biomer, a segmented polyether polyurethane, has high flexibility and shows the most stable behavior during cyclic deformation regardless of test environment. Toyobo TM5, a similar segmented polyurethane to Biomer, has higher strength and ductility than Biomer, although its static and dynamic flexibility are slightly worse and less stable than those of Biomer. These results indicate that Biomer and Toyobo TM5 are more suitable for flexible components of cardiac prostheses.
    Additional Material: 9 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 133-144 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A new material test system has been designed to evaluate the mechanical properties of biomaterials which are very often subject to complicated dynamic and repetitive force and deformation inside the body. The test system has high versatility, being incorporated with a miniature servohydraulic testing machine which can smoothly apply various modes of load and deformation to materials, and a vidicon displacement analyzer for the accurate, non-contact measurement of specimen length. A minicomputer system is used for the data acquisition and processing. Performance tests of the system and preliminary experiments on elastomeric polymers have indicated that the test system is very useful for the detailed studies of the mechanical properties of various kinds of biomaterials.
    Additional Material: 10 Ill.
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  • 7
    Publication Date: 1997-05-01
    Print ISSN: 1352-2310
    Electronic ISSN: 1873-2844
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences , Physics
    Published by Elsevier
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  • 8
    Publication Date: 2016-08-10
    Print ISSN: 0021-9541
    Electronic ISSN: 1097-4652
    Topics: Biology , Medicine
    Published by Wiley
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  • 9
    Publication Date: 1972-05-05
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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