Structures reentrant

The transformation of closed cell polymethacryUmide and LDPE foams are described in an attempt to impose reentrant structures on them. New methods of achieving permanent, triaxial compression were developed. 9 refs. 

Atrial fibrillation For the prevention of paroxysmal atrial fibrillation/flutter (PAF) associated with disabling symptoms and paroxysmal supraventricular tachycardias (PSVT), including atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, and other supraventricular tachycardias of unspecified mechanism associated with disabling symptoms in patients without structural heart disease. 

Dillon SM, Allessie MA, Ursell PC, Wit AL Influences of anisotropic tissue structure on reentrant circuits in the epicardial border zone of subacute canine infarcts. Circ Res 1988 63 182-206. 

Fig. 43. (a and b) Resistivity versus temperature curves for HoNi2B2C and Yo.isHoo.8sNi2B2Ct respectively, showing reentrant behaviour, (c and d) The comparison with the neutron diffraction peak intensities shows that the a structure is strongly related to the reentrant behaviour, (e and f) Upper critical field determined from the resistive transitions shown in (a) and (b) (Eversmann et al. 1996 Milder et al. 1997 Kreyssig et al. 1997). 

It is obvious that the commensurate antiferromagnetic structure of fig. 39a coexists with superconductivity in HoNi2B2C, similar as in DyNi2B2C. On the other hand, as can be seen in fig. 43(a and c) the superconductivity is suppressed in the small temperature range where the two incommensurate magnetic structures of fig. 39(b and c) occur. Now the question is which of these two structures is more relevant for the near-reentrant behaviour. In Y().i5Hoo.85Ni2B2C the situation is totally different (fig. 43(b and d)). Here the a ... 

Furthermore, it has been found that the so-called reentrant jumpwise collapse can be realized when a charged network swells in a mixed solvent [31]. In this case, the network having a globular structure both in A or B one-component solvents decollapses sharply in some intermediate composition range or the network swollen in pure solvent shrinks abruptly in mixed solvent (Fig. 7). 

An exception to the rule that lowering the Iciiiperaiure cutises transitions to phases with increased order sometimes occurs for polar compounds w hich form the smectic l. phase (a layered structure formed by molecular dimers). Decreasing the temperature cutises u transition front nematic to smectic. 1,.,. but a further lowering of the temperature produces J transition back to the nematic phase tcalled the reentrant nematic phase). Electric or magnetic fields also may induce mesomorphic phase transitions. 

A novel method for achieving low thermal impedance between the chip and substrate has been developed at Stanford University (163-165). Reentrant microcapillaries (3-5 (xm wide) are etched into the substrate (either a silicon wafer or a ceramic coated with a polyimide) and partially filled with a fluid such as silicone oil. This structure increases the heat-transfer area, reduces the interfacial thermal resistance, and provides a stress-free, re-... 

Dertinger (2001) also found that the a-axis modulated structure a of Figure 39 is much more sensitive to pressure, compared to the other two magnetic structures of Figure 39, and it even disappears at relatively low values of P. Interestingly he observed near-reentrant behavior also at temperatures and pressures where the a structure had disappeared. Therefore he concluded that the near-reentrant behavior in H0M2B2C cannot mainly be caused by the presence of the a incommensurate magnetic structure. This problem will be further discussed in the next Section 4.9.4. 

Fig. 4. A homology model of the channel domain of an NMDA receptor (Chohan et al, 2000) based on the structure of the KcsA channel (Doyle et al, 1998). (A) The side view of the channel is shown with only the Ml, M2, and M3 regions and each of the four subunits in a different color. Note that M2 is a reentrant pore loop that enters the pore from the cytoplasmic face of the membrane. (B) A view of the channel from the extracellular side of the membrane is shown. Both selectivity and gating is controlled at least partially by the M2 region. (See Color Insert.)...

Reentrant superconductivity is known from so-called ferromagnetic superconductors like ErRh4B4 where the ferromagnetic transition at lower temperatures actually destroys superconductivity [244]. However, the exact magnetic structure in k-(ET)2Cu[N(CN)2]C1 is still unknown and the origin of the peculiar behavior is at present subject of speculations only. 

In the re-entrant transition from the insulating to the metallic state with decreasing temperature just the restoration to the metallic state has been found in electrical, magnetic and structural properties. It is not surprising to have the reentrant transition because of the free energy of the system. The metallic state s free energy is expected to be proportional to - T because of the electronic heat... 

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