Glass state

Stanley H E 1999 Unsolved mysteries of water In Its liquid and glass states MRS Bull. May 22-30... 

Friedrieh has studied the free-base eytoehrome c in a glass state at 1.6 K (96MI77). In general, for free-base protoporphyrins it ean be safely assumed that the hole-burning photoreaetion is based on a light-indueed rearrangement of the inner protons. This type of reaetions has been verified for all free-base porphyrin moleeules [92MI(61)381]. 

Finally, if there are a large number of stored patterns, there may enough mutual interference to give rise to local minima, or inetastable states - sometimes also called spin glass states to emphasize the similarity between the formalisms of Hopfield nets and spin glasses - that are not correlated with any subset of the set of stored patterns [amitSSb]. 

Several methods are employed to allow the observation of phosphorescence. One of the most common techniques is to supercool solutions to a rigid glass state, usually at the temperature of liquid nitrogen... 

In contrast, the flexibility of amorphous polymers above the glass state is decreased when stiffening groups (structures 2.10 through 2.13) are present in the polymer backbone ... 

In this contribution we focus on the region that is sandwiched between the FE and glass phase states, i.e. the range of x-values 0.20 < x < 0.35. In [10] we have shown that the low temperature glass state (0.35 < x < 0.65) consists predominantly of short range ordered AFE clusters with a mean correlation length of about 1 nm. The fact that no FE clusters were found was explained by the unfavourable ratio of electric surface to volume energy, which makes... 

The temperature dependence of the FE and glassy volume fractions was determined for the four different compositions mentioned above (Fig. 10). Whereas D-RADP-0.20 exhibits a quasi-continuous sequence of local PE-FE phase transitions with a coexistence range of about 20 K and a pure FE phase state throughout the whole crystal below 135 K [17], in D-RADP-0.25 part of the crystal remains in the PE or glass state, respectively, down to very low temperatures. This is also observed in D-RADP-0.30, while in D-RADP-0.35 (not shown) no FE polarization could be observed at all. 

At each temperature the equilibrium spin glass state is considered to consist of a ground state plus thermally activated droplet excitations of various sizes. A droplet is a low-energy cluster of spins with a volume if and a fractal surface area L. The typical droplet free-energy scales as... 

In the next sections I briefly discuss some of the theoretical concepts important to understanding the glass state and nonequilibrium aging dynamics. 

Ice-cream. Crystallization of lactose in ice-cream causes a sandy texture. In freshly hardened ice-cream, the equilibrium mixture of a- and /1-lactose is in the glass state and is stable as long as the temperature remains low and constant. During the freezing of ice-cream, the lactose solution passes through the labile zone so rapidly and at such a low temperature that limited lactose crystallization occurs. 

In general, ordinary substances which can be frozen-in by supercooling will not convert to the glass state when cooled infinitely slowly, whereas for substances... 

In the melt of a two-component system, polymer-plasticizer, the segments of a macromolecule and the molecules of the plasticizer are arranged in such a way that almost no holes exist (Figure 3a). In the glass state such an arrangement is no... 

The condition for valid results in this work is the fact that the system is in the gel-state that is, it is in a state of inner equilibrium, and not in the glass state. Measurements of Hellwege, Knappe, and Lehmann (5) on pure PVC show the expected discontinuity in the compressibility vs. pressure curve at the melting point transition in the glass state. It is inferred from this study that the glass temperature for pure PVC and for the plasticized, gel-type PVC does not rise above 110° C. at pressures of 200 atm. (Figure 7). Our study showed that the system is always in a state of inner equilibrium. 

The linear relationship between compressibility and temperature is valid only when the system is in a state of inner equilibrium. If it should pass over into the glass state or if the gas dissolved in the system is liberated, a sharp deviation from the linear temperature relationship ensues (Figure 11). If the compressibility is plotted as a function of pressure, there is no simple functional relationship, and an expansion of material can not be identified with a deviation in the trends of curvature. Figure 10 illustrates an example. 

The model of Condo permits the determination of the limiting pressure at which the glass state exists, on the basis of a reduced number of parameters (only the glass transition temperature of the pure polymer is needed to calibrate the energy parameter) for this reason, it seems particularly useful for the prediction of the plasticizing effects. 

Lactose in the glass state may be used as a protective coating on certain materials, either to seal in components or to protect the material from the environment. Materials may be coated with lactose solution and dried, or a solution containing the material and lactose can be spray-dried. This latter application has been used to preserve enzymatic activity during spray drying and storage (Nickerson 1974). 

Whereas the disclination picture provides a convincing explanation of the properties of multilayers of fatty acids, being consistent with both the electron diffraction and optical evidence, it is not yet proven that, at room temperature, such systems are really in the hexatic state. It is equally probable that the existence of an initial hexatic monolayer on which subsequent layers are grown by epitaxy produces a material which is far from thermal equilibrium and has more of the nature of a glass state rather than of a mesophase. Indeed, the relative hardness of multilayers and their resemblance to true three-dimensional crystals of fatty acids tends to support this view. 

Sr2YR.uC>6 superconducts when it is doped with only 1% Cu on Ru sites [1], The superconductivity sets in at D49 K and becomes rather extensive at 30 K (when a spin-glass state appears) but does not become complete until 23 K when the Ru librations freeze out. 

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