scholarly journals Three-dimensional characterization of resorption cavity size and location in human vertebral trabecular bone

Bone ◽  
2012 ◽  
Vol 51 (1) ◽  
pp. 28-37 ◽  
Author(s):  
M.G. Goff ◽  
C.R. Slyfield ◽  
S.R. Kummari ◽  
E.V. Tkachenko ◽  
S.E. Fischer ◽  
...  
Keyword(s):  
Trabecular Bone ◽  
Three Dimensional ◽  
Cavity Size ◽  
Vertebral Trabecular Bone

A Methodology for Mechanical Measurements of Technical Constants of Trabecular Bone

1988 ◽  
Vol 17 (4) ◽  
pp. 169-173 ◽  
Author(s):  
L H Yahia ◽  
G Drouin ◽  
P Duval
Keyword(s):  
Trabecular Bone ◽  
Three Dimensional ◽  
Lumbar Vertebrae ◽  
Bony Tissue ◽  
Ultrasonic Methods ◽  
Vertebral Trabecular Bone ◽  
Young’S Moduli ◽  
Orthotropic Properties ◽  
First Time ◽  
Non Destructive

Vertebral trabecular bone was tested by non-destructive uniaxial and triaxial loadings with the purpose of investigating the orthotropic properties of bone. A triaxial testing apparatus using hydrostatic pressure was developed and allowed to characterise the bony tissue in a three-dimensional stressed state. Thirty specimens, in the form of 10 mm cubes, were tested. The Young's moduli obtained in this study for the trabecular bone of human lumbar vertebrae are found to be in agreement with the values obtained by ultrasonic methods. Analyses of triaxial compressive tests provided, for the first time, the Poisson's ratios of vertebral trabecular bone. These values are found to satisfy thermodynamic restrictions established by Cowin and Van Buskirk (1986). Finally, no significant differences in the material properties were found for segment level (L3-L4).

Characterization of synthetic foam structures used to manufacture artificial vertebral trabecular bone

2017 ◽  
Vol 76 ◽  
pp. 1103-1111 ◽  
Author(s):  
David Fürst ◽  
Sascha Senck ◽  
Marianne Hollensteiner ◽  
Benjamin Esterer ◽  
Peter Augat ◽  
...  
Keyword(s):  
Trabecular Bone ◽  
Vertebral Trabecular Bone

Contributions of Trabecular Rods of Various Orientations in Determining the Elastic Properties of Human Vertebral Trabecular Bone

2007 ◽  
Author(s):  
Xiaowei S. Liu ◽  
X. Henry Zhang ◽  
Paul Sajda ◽  
Punam K. Saha ◽  
Felix W. Wehrli ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Trabecular Bone ◽  
Elastic Properties ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Micro Computed Tomography ◽  
Bone Volume Fraction ◽  
Human Trabecular Bone ◽  
Vertebral Trabecular Bone ◽  
Age Related

Osteoporosis is an age-related disease characterized by low bone mass and architectural deterioration. Other than bone volume fraction (BV/TV), microarchitecture of trabecular bone, such as trabecular type (rods or plates), connectivity, and orientation of the trabecular network is also believed to be important in governing the mechanical properties of trabecular bone. A recent study [1] showed that the microarchitecture alone affects elastic moduli of trabecular bone and, further, that trabecular plates make a far greater contribution than rods. In human vertebral trabecular bone, the roles of transverse vs. vertical rods in conferring mechanical properties of trabecular bone have been debated [2, 3]. It has been suggested that the role of transverse trabecular rod is critical in determining elastic modulus of vertebral trabecular bone. However, without explicit classifications of trabecular type, or orientation assessment at an individual trabecula level, it is not possible yet to test this hypothesis in human trabecular bone samples despite the development of three-dimensional (3D) micro computed tomography (μCT) and μCT based finite element (FE) models of human trabecular bone. With the newly developed technique of complete volumetric decomposition and individual trabecula based orientation analyses [4], now it is possible to quantitatively examine the contributions of trabecular rods of various orientations in the elastic properties of vertebral trabecular bone.

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

convergent-beam diffraction from surfaces

1987 ◽  
Vol 45 ◽  
pp. 30-33
Author(s):  
J. A. Eades ◽  
A. E. Smith ◽  
D. F. Lynch
Keyword(s):  
Reciprocal Lattice ◽  
Three Dimensional ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Plane Figure ◽  
Transmission Electron ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

It is quite simple (in the transmission electron microscope) to obtain convergent-beam patterns from the surface of a bulk crystal. The beam is focussed onto the surface at near grazing incidence (figure 1) and if the surface is flat the appropriate pattern is obtained in the diffraction plane (figure 2). Such patterns are potentially valuable for the characterization of surfaces just as normal convergent-beam patterns are valuable for the characterization of crystals.There are, however, several important ways in which reflection diffraction from surfaces differs from the more familiar electron diffraction in transmission.GeometryIn reflection diffraction, because of the surface, it is not possible to describe the specimen as periodic in three dimensions, nor is it possible to associate diffraction with a conventional three-dimensional reciprocal lattice.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

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