Phase stress-induced

Another property pecuHar to SMAs is the abiUty under certain conditions to exhibit superelastic behavior, also given the name linear superelasticity. This is distinguished from the pseudoelastic behavior, SIM. Many of the martensitic alloys, when deformed well beyond the point where the initial single coalesced martensite has formed, exhibit a stress-induced martensite-to-martensite transformation. In this mode of deformation, strain recovery occurs through the release of stress, not by a temperature-induced phase change, and recoverable strains in excess of 15% have been observed. This behavior has been exploited for medical devices. 

V.V. Martynov, X-ray diffraction study of thermally and stress-induced phase transformations in single... 

First of all the term stress-induced crystallization includes crystallization occuring at any extensions or deformations both large and small (in the latter case, ECC are not formed and an ordinary oriented sample is obtained). In contrast, orientational crystallization is a crystallization that occurs at melt extensions corresponding to fi > when chains are considerably extended prior to crystallization and the formation of an intermediate oriented phase is followed by crystallization from the preoriented state. Hence, orientational crystallization proceeds in two steps the first step is the transition of the isotropic melt into the nematic phase (first-order transition of the order-disorder type) and the second involves crystallization with the formation of ECC from the nematic phase (second- or higher-order transition not related to the change in the symmetry elements of the system). 

Very frequent are the cases of stress-induced crystallizations. A typical case is that of slightly vulcanized natural rubber (1,4-m-polyisoprene) which, under tension producing a sufficient chain orientation, is able to crystallize, while it reverts to its original amorphous phase by relaxation [75],... 

Various types of work in addition to pV work are frequently involved in experimental studies. Research on chemical equilibria for example may involve surfaces or phases at different electric or magnetic potentials [11], We will here look briefly at field-induced transitions, a topic of considerable interest in materials science. Examples are stress-induced formation of piezoelectric phases, electric polarization-induced formation of dielectrica and field-induced order-disorder transitions, such as for environmentally friendly magnetic refrigeration. 

Knight, D. P., Knight, M. M., and Vollrath, F. (2000). Beta transition and stress-induced phase separation in the spinning of spider dragline silk. Int. J. Biol. Macromol. 27, 205-210. 

In addition to the fact that carbon formed by gas-phase pyrolysis is chemically different from that which forms catalytically on Ni, it is important to recognize that carbon formed by pyrolysis forms on the surface rather than in the bulk of the material. Because of this, pyrolysis does not result in pitting of the surfaces to which the hydrocarbon is exposed. Furthermore, on porous Ni cermets, carbon fiber formation can lead to fracture of the electrode caused by the stresses induced by the carbon fibers. Such stresses do not occur upon deposition of pyrolytic carbon. 

Exposure of the SECs to pathogens or cytokines produced by other cells during stress induces activation of the SECs and subsequent production of cytokines, eicosanoids, and/or adhesion molecules. For instance, after activation with EPS, a main component of the walls of gramnegative bacteria and a major inducer of inflammation and non-specific immune functions [20], SECs produce a number of pro- and anti-inflammatory cytokines. Pro-inflammatory cytokines shown to be produced were tumour necrosis factor alpha (TNFa) [26] interleukin-1 alpha/beta(IL-lo/p) [27] the major inducer of acute phase proteins interleukin-6 (IL-6) [28] and the neutrophil chemo-attractant interleukin-8 (IL-8) [29]. Anti-inflammatory cytokines shown to be produced were interleukin-10 (IL-10) [27] and hepatocyte growth factor (HGF) [30]. 

Perhaps, the most dramatic example of the effects of drawing on the spectra of a polymer comes from the stress-induced crystal transition of poly(butylene terephtha-late) 292,29 298 299). The phase transition of PTMT has been investigated above and below the glass transition temperature by means of dynamic infrared measurements... 

Some deviations of theory from the experiment should be noted as well. We were unable to observe phase transitions induced by compression of the gels. In. some cases, under conditions of free swelling jumpwise transitions were observed while the transitions induced by tensile stress were continuous. Such a smoothing of the transition is apparently a result of partial destruction of the gels under the mechanical external action. The fact that the shape of the samples, as a rule, was not restored after the mechanical stress was removed is in favor of the assumption. 

Uniaxial stress-induced phase transition in gels [29]. The changes in diameter and length of cylindrical N-isopropylacrylamide gels were measured under uniaxial stress along the axis. The transition temperature and discontinuity were increased with increasing stress, which indicates the possibility of the... 

Phase transition in gels can be affected by applying uniaxial stress. With increasing stress in the region below 1 x 104 N m 2 at gelation, the effects of uniaxial stress was qualitatively described by the mean field theory. The present results clearly indicate the possibility of a uniaxial stress-induced phase transition of gels. 

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