Pinning sites

Infection can complicate these fractures either at the pin-site infection, deep within the wound or osteomyelitis. 

Sintered density (pore) pore becomes a pinning site of domain wall that prevents domain wall motion (Fig. 6.1.2). 

Decker and Gar off have conducted a fairly systematic study of the shapes of lines of contact in the presence of numerous pinning sites. The substrate they worked with was a fluoro-polymer, which they progressively degraded by exposing it to ultraviolet radiation. With water, the appearance of a typical line on a degraded substrate is illustrated in Figure 3.7. 

Figure 9.2 Due to the high contact angle and low hysteresis, liquid droplets easily roll off superhydrophobic surfaces. However, damage to the surface often leads to an increased contact angle hysteresis and, consequently, droplets stick to the surface, (a) A hydrophobic surface coating on a roughness pattern may get easily worn off, and hydrophilic bulk material will be exposed as a result, (b) If the roughness features are fabricated of hydrophobic material, wear will not introduce hydrophilic pinning sites [22].

Lattice mismatch. In semiconductor systems lattice mismatches of only a few percent, or less, are desired to reduce the number of dislocations in the film. In ceramic thin films larger mismatches (generally <15%) are tolerated because higher defect densities in the film are acceptable. In some situations a certain number of defects are actually beneficial to film properties (they can provide pinning sites in high-temperature superconductors that can trap magnetic flux lines). 

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