Elasticity super

Excited states can be formed by a variety of processes, of which the important ones are photolysis (light absorption), impact of electrons or heavy particles (radiolysis), and, especially in the condensed phase, ion neutralization. To these may be added processes such as energy transfer, dissociation from super-excited and ionized states, thermal processes, and chemical reaction. Following Brocklehurst [14], it is instructive to consider some of the direct processes giving excited states and their respective inverses. Thus luminescence is the inverse of light absorption, super-elastic collision is the inverse of charged particle impact excitation, and collisional deactivation is the inverse of the thermal process, etc. 

Currently all commercial vena cava filters are fabricated from either nitinol (nickel and titanium alloy), phynox (nickel, cobalt, chromium, iron, and molybdenum alloy), or stainless steel wire in various catheter sheath sizes ranging from 7 to 14 French (2.3-4.7 mm diameter). These metals have been chosen because they are biostable and have low thrombogenicity. This means that blood is less likely to form clots on the surface, and cells are not encouraged to grow around the device. Moreover, nitinol is a thermal shape-memory and super-elastic alloy that is self-expanding after deployment. For this particular application the nitinol will be tuned to expand on exposure to body temperature." ... 

Above the transition temperature an extraordinary elasticity can be observed in the shape memory alloys. Figure 6.53 shows a uniaxial stress-strain diagram of a pseudo-elastic (or super-elastic) SMA. 

Metals share excellent mechanical and conductivity (electrical and thermal) properties ideal for high stress apphcations such as heart valves. Titanium—nickel alloys have become the most common material for metaUic cardiovascular applications (stents and valves) due to unique properties shape memory effect, super-elasticity, high degree of biocompatibility moreover, they are almost completely inert and nonmagnetic. 

It is also possible to apply a stress to the material in its high-temperature austenitic phase. However, since the temperature is above Af, the original shape will be reformed immediately after the load is removed. Such an immediate shape change is referred to as pseudoelasticity (or super elasticity), and is the active principle underlying cellular phone antennae that may be greatly distorted only to immediately return to their original shapes. 

Linge L and Dahm S, Practical aspects of using super-elastic archwires for edgewise technique , Eortschr. Kieferorthop., 1994, 55, 324-9. 

Falvo A, Futgiuele FM, Maletta C (2005) Laser welding of a Nili alloy Mechanical and shape memory behavior. Materials Science and Engineering A. 412 235-240 Wu MH (2001) Fabrication of Nitinol materials and components. Proceedings of the international conference on shape memory and super-elastic technologies, Kunming, China, 285-292... 

Whilst the first relationship, equation (5), has been confirmed experimentally the equality of the electron scattering asymmetry with the circular polarisation of the coincident photons has so far not been tested. However, Hermann and Hertel have performed a related experiment in which an electron scattering asymmetry was measured for super-elastic collisions with sodium atoms excited by circularly polarised laser light. 

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