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Full-Text Articles in Engineering
Effect Of Applied Uniaxial Stress On Rate And Mechanical Effects Of Cross-Linking In Tissue-Derived Biomaterials, Debbie Chachra, Paul Gratzer, Christopher Pereira, J. Lee
Effect Of Applied Uniaxial Stress On Rate And Mechanical Effects Of Cross-Linking In Tissue-Derived Biomaterials, Debbie Chachra, Paul Gratzer, Christopher Pereira, J. Lee
Debbie Chachra
Conformational changes in collagen fibrils, and indeed the triple helix, can be produced by application of mechanical stress or strain. We have demonstrated that the rate of cross-linking in glutaraldehyde and epoxide homobifunctional reagents can be modulated by uniaxial stress (strain). Two poly(glycidyl ether) epoxides were used: Denacol® EX-810 (a small bifunctional reagent), and Denacol EX-512 (a large polyfunctional reagent). To prevent any possible effect from being masked by saturation of cross-linking sites, bovine pericardium was cross-linked to such an extent that the increase in collagen denaturation temperature, Td, was one-half of the maximal rise achievable with …
The Effect Of Different Hormone Replacement Therapy Regimens On The Mechanical Properties Of Rat Vertebrae, Debbie Chachra, M. Kasra, Carla Vanin, N. Maclusky, R. Casper, Marc Grynpas
The Effect Of Different Hormone Replacement Therapy Regimens On The Mechanical Properties Of Rat Vertebrae, Debbie Chachra, M. Kasra, Carla Vanin, N. Maclusky, R. Casper, Marc Grynpas
Debbie Chachra
The purpose of this study was to examine the effects of estrogen replacement, in concert with three different progestin regimens, on the mechanical properties of rat lumbar vertebrae. Ninety-two Sprague-Dawley rats (11 months old) were divided into six groups for treatment. The first group was an intact control, the second group (OVX) was ovariectomized only, and the third group (estrogen-only) was ovariectomized and received continuous estrogen through a 17-estradiol implant. The remaining groups were ovariectomized and received estrogen and progestin (norethindrone, NET) therapy; 3 g of NET was injected daily (estrogen plus continuous NET), or 6 g of NET was …
A New Tool To Assess The Mechanical Properties Of Bone Due To Collagen Degradation, C. Wynnyckyj, S. Omelon, K. Savage, M. Damani, Debbie Chachra, Marc Grynpas
A New Tool To Assess The Mechanical Properties Of Bone Due To Collagen Degradation, C. Wynnyckyj, S. Omelon, K. Savage, M. Damani, Debbie Chachra, Marc Grynpas
Debbie Chachra
Current clinical tools for evaluating fracture risk focus only on the mineral phase of bone. However, changes in the collagen matrix may affect bone mechanical properties, increasing fracture risk while remaining undetected by conventional screening methods such as dual energy x-ray absorptiometry (DXA) and quantitative ultrasound (QUS). The mechanical response tissue analyzer (MRTA) is a non-invasive, radiation-free potential clinical tool for evaluating fracture risk. The objectives of this study were two-fold: to investigate the ability of the MRTA to detect changes in mechanical properties of bone as a result of treatment with 1 M potassium hydroxide (KOH) and to evaluate …
Local Mechanical Spectroscopy With Nanometer-Scale Lateral Resolution, Nancy Burnham, F Oulevey, G Gremaud, A Semoroz, Aj Kulik, E Dupas, D Gourdon
Local Mechanical Spectroscopy With Nanometer-Scale Lateral Resolution, Nancy Burnham, F Oulevey, G Gremaud, A Semoroz, Aj Kulik, E Dupas, D Gourdon
Nancy A. Burnham
A new technique has been developed to probe the viscoelastic and anelastic properties of submicron phases of inhomogeneous materials. The measurement gives information related to the internal friction and to the variations of the dynamic modulus of nanometer-sized volumes. It is then the nanoscale equivalent to mechanical spectroscopy, a well-known macroscopic technique for materials studies, also sometimes called dynamic mechanical (thermal) analysis. The technique is based on a scanning force microscope, using the principle of scanning local-acceleration microscopy (SLAM), and allows the sample temperature to be changed. It is called variable-temperature SLAM, abbreviated T-SLAM. According to a recent proposition to …
Interpretation Issues In Force Microscopy, Nancy Burnham, Richard Colton, Hubert Pollock
Interpretation Issues In Force Microscopy, Nancy Burnham, Richard Colton, Hubert Pollock
Nancy A. Burnham
In this paper, we will discuss force microscopy (FM) and its potential for determining mechanical properties of thin films. We will introduce the basic principles of FM, and demonstrate how FM can be used to determine materials properties as well as image surface topography, both with nanonewton or sub‐nanonewton force resolution and sub‐nanometer position resolution. As FM is still a new field, not all of the questions concerning interpretation have been fully answered. We will elucidate four current issues that must be resolved before the full potential of FM can be realized. They are: (1) the role of water vapor …