Mechanical mismatch

Keywords Charge injection Charge transfer Hopping mechanism Mismatches... 

Nanofibrous structures have been extensively smdied as the two- or three-dimensional scaffolds that mimic the cell living environment for tissue regeneration. Nanofibrous structures provide temporary spaces with a mnable porosity in which cells can exchange metabolites and nutrients with their environment so that cellular functionality can be maintained, the reconstruction of tissues can be aided, and the tailored mechanical properties will function as desired, and the wound bed can be protected from collapsing, and mechanical mismatch between scaffolds and host tissues can... 

Two competing types of phenomena that arise at the ferroelectric interfaces can affect the properties of the superlattices. The strain field, generated by the mechanical mismatch between superlattice layers, influences the polarization orientation and generally increases the ferroelectric transition temperature Tc [32]. In contrast, the electric depolarization field, produced by interfacial surface charges is unfavorable to formation of the ferroelectric phase [33]. In fact, in cubic perovskite-like ferroelectrics the situation can be even more complex due to both 180° ferroelectric [27] and 90° ferroelastic [21, 32, 34] domain formation. 

Mechanical properties are also important for other applications where mechanical strength is not the primary function. One such application is electrodes for stimulation or recording in the brain. Silicon microelectrodes inevitably seem to elicit astroglial scar due to mechanical mismatch with... 

Cerebral aneurysms treated by traditional endovascular methods using noble metal (platinum) -based coils have a tendency to be unstable, due to chronic inflammation, compaction of coils, or growth of the aneurysm. In addition, with physical limitation, mechanical mismatch between hard metal and the thinned, weakened wall, aneurysms exhibit a potential for rupture. Maitland et al. addressed this issue and developed a new filling... 

The third approach is in the implantation of functional tissue that is developed ex vivo. This approach attempts to create a biological substitute made from synthetic materials to be used as grafts or cardiac patches for treating HF. Clinically used materials include synthetic woven Dacron, extended polytetrafluoroethylene (ePTFE), and natural glutaraldehyde-fixed pericardium. These materials, however, have limited success rates due to thrombosis, inflammatory response, mechanical mismatch between native tissue and implants, aneurysm, and lack of remodeling for natural materials. ... 

However, flexural strength, strain-to-failine, and fracture toughness values of HA-ceramics are significantly less than those of bone, whereas the elastic modulus is much higher [8, 9], These mechanical mismatches influence the reliability of ceramics when implanted into the bone tissue. To improve the mechanical compatibility, a composite approach may be promising. The combination of different materials within a composite structure may lead to a composite material that reveals specific physical, chemical and/or mechanical properties, particularly resulted from a synergy principal. 

The comparison shows that the thermo-mechanical mismatch, characterized by the CTE, is significantly higher for MID than for printed-circuit boards. This means that higher compression/tension strains than in FR4, for example, can occur at the substrate/conductor, conductor/connection medium, and connection-medium/com-ponent boundaries (Eig. 5.2). On account of the differences between the individual materials, differences in long-term reliability can be expected, depending on the conditions of use. [178]... 

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