Melt-textured

Three different whey protein products extruded at the cook temperature of 75 °C resulted in varying degrees of melt texturization (Table 5.3). Among the whey proteins, WPC (WPC80) was the least texturized. Whey lactalbumin (WLAC) and WPI were both significantly (p < 0.05) more texturized, but a wider spread of texturization was observed for WPI, the initial and final values were from 28% to 94.8%, and therefore more emphasis was placed on studying WPI (Onwulata et ah, 2006). 

Understanding of vortex pinning mechanisms will steadily develop and with it the technology of optimising compositions and structures of materials for trapped field magnets, particularly the melt-textured, large grain varieties. 

Here, v represents the surface tension of a smooth film, whereas r, and r2 are the principal radii of the formed hole. Suh (1983) has shown that for the case of a tellurium film, energy barrier to restore a planar surface is small and pit formation ensues for a melted textured surface. 

The plant cell wall is a composite of cellulose (the main fibre) plus shorter lengths (hemicellulose) that help bind the fibre, plus pectin (the main matrix adhesive) and some proteins. There are fruits that have a soft melting texture when ripe (e.g., avocado and blackberry) in which the cell wall swells noticeably. This swelling is related to the degree of solubilisation of the pectin (Redgwell et al. 1997) which can be removed in vitro using enzymes or other chemicals. 

For optimum fruit quality, almost all pear varieties need a warm site, rather similar to that required for wine grapes. If these conditions are not present, the fruit very often does not have the desired melting texture and has little flavour in extreme cases the fruit may taste carroty . This applies particularly to late-ripening cultivars. Pear trees are somewhat more sensitive to winter frost than apple trees, and are at severe risk from late frosts because flowering is about 10 days earlier. 

Murakami, M., Flux pinning of melt textured processed YBCO superconductors and their applications, in Studies of High Temperature Superconductors, Vol. 9 (A. V. Narlikar, ed.). Nova Science, New York, 1991, pp. 1. 

The last technique to be discussed in the context of measurements is an ac method proposed by Campbell (1969) and modified by Rollins et al. (1974), which is particularly well suited for measurements on bulk samples e.g., melt-textured HTS. A schematic view of its basic principles is shown in fig. 10. Assume that a Bean-like flux profile has been established by a certain dc field well above the full penetration field, If a small ac ripple field of amplitude Aac is superimposed parallel to the dc field, the flux profile near the sample surface is modified accordingly (as shown by the shaded area in fig. 10). With... 

Fig. 13. Measiirement of the ac susceptibility on a melt-textured superconductor (Wacenovsky 1993). Top panel in-phase signal middle panel out-of-phase signal bottom panel third harmonic.

The first conjecture is ruled out by all data on all forms of 123 superconductors, i.e., it turns out that decreases immediately if d starts to deviate from its optimum value. This is illustrated in fig. 32, where is plotted as a function of magnetic field in melt-textured Y-123 superconductors H c) with transition temperatures between 92.4 and 45.8 K (Wisniewski et al. 1996). The data deliberately refer to very low temperatures (5 K in this case), in order to minimise the influence of variations in Tc- A very similar behaviour is found for the irreversibility lines (IL s) as shown in fig. 33 for H c, i.e.. 

Fig. 32. Critical curient deosities versus applied field (at 5K) in melt-textured Y-123 bulk superconductors HII c) with various degrees of oxygen deficiency (Wisniewski et al. 1996).

Melt-textured materials (Y-123, Nd-123) with U admixtures represent a highly promising system for high-Jc applications due to the possibihty of forming randomly oriented fission tracks (cf. sect. 6.3). Results on the critical current densities (taken by the flux-profile technique, i.e. in the nearly unrelaxed state) are shown in fig. 40 (Weinstein et al. 1998, Eisterer et al. 1998). 7c following thermal neutron irradiation to the optimal... 

Fig. 38. Fast neutron irradiation of a Nd-123 melt-textured superconductor (Kem 1997) (a) critical current density (H 1 c) versus field at 77 K (prior to and following irradiation to a fluence of 2 x 10 m", >0.1 MeV) (b) irreversibility lines for ti c, same conditions as above.

Fig. 40. (a) Critical current densities H c) in melt-textured Y-123 with an admixture of 0.3 wt% uranium at various temperatures. The open symbols refer to a reference sample, the solid symbols to a sample exposed to a thermal neutron fluence of 4xl0 m (Weinstein et al. 1998). (b) Sequential thermal neutron irradiation of a melt-textured Y-123 superconductor with an admixture of 0.3 wt% uranium. Critical current densities H c) versus field at 77K (open squares urrirradiated, solid squares 1.8x10 m", crosses 4.2xl0 m, Eistereret... 

As melt-textured samples cannot directly be produced in sufficiently large sizes for special applications, several other techniques have recently undergone successful testing to join textured blocks to larger monoliths. In contrast, bulk YBCO samples can much more easily be shaped at low oxygen pressure and temperature below 700 °C, via the formation of YBa2Cu Cu2 0,5 this is followed by oxidation and hot-isostatic pressing (HIP) to yield very compact material in different shapes. 

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