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Structure and Rheology of Sheared Colloidal Suspensions

Colloidal suspensions – where micro-size or nano-size particles are suspended in a fluid – exhibit various equilibrium structures ranging from face-centered and cubic-centered crystals to binary ionic crystals, and even kagome lattices. When driven out-of-equilibrium by shear, even more diverse colloidal structures can be accessed. These structures lead to unique flow behaviors of suspensions.

Quasi-Static Shear Mechanical Properties of Articular Cartilage

Articular cartilage, the soft connective tissue that coats bones in joints, is a highly complex and inhomogeneous material. It is made up of a fluid-saturated, cross-linked network of collagen fibrils whose orientation and porosity vary with depth from the articular surface. Interspersed among the network are cells and highly charged molecules called proteoglycans. Cell shape, cell density and proteoglycan density are all also spatially dependent.  

High-Resolution Measurement of Shear Mechanical Properties in Articular Cartilage Using GRATE and WAND

Local mechanical properties in articular cartilage and other biological tissues are typically measured by tracking the displacement of cells, cell nuclei and other fiducial markers using particle image velocimetry (PIV) and other feature-tracking methods (see "Quasi-Static Shear Mechanical Properties of Articular Cartilage").  However, these techniques are limited in spatial resolution by the density of trackable markers.  In adult articular cartilage, intervertebral disk and other soft tissues, cells can be very sparse.  Therefore, we have developed grid-resolution automated tissue elastog

Anatomic Variation of Articular Cartilage Depth-Dependent Shear Properties

Articular cartilage (AC), a biological tissue that protects and lubricates joints, plays a critical role during healthy locomotion.  While much is known about this tissue's biochemistry and compressive mechanical properties, comparatively less attention has been given to its shear mechanical properties.  This represents a critical knowledge gap because cartilage tissue experiences significant shear under normal loading conditions, and may indeed most frequently fail in such circumstances.


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