Equilibrium amorphous ices

Figure 3 Different methods of hydrate formation (1-5) each can give a distinct perspective on certain aspects of hydrate formation l-ice + gas at T< 273K 2- ice with the temperature ramped above T = 273K 3 - amorphous ice +gas at T < 13 OK 4 and 5, either quiescent or with agitation are usually used for phase equilibrium studies and the effect of inhibitors. Simulation of natural gas hydrate requires the addition of sediment at various levels of water-sediment content.

The pressure-density isotherms of various water models in supercooled region, obtained in simulations, can be directly compared with the available experimental isotherms, showing transformations between amorphous ices upon compression." Experimental measured isotherms are unavoidably affected by the transformation kinetics and by the strong hysteresis. These two effects may be reduced by using slow compression rates and higher temperatures, respectively. Therefore, the equilibrium isotherms obtained in simulations we compare with the experimental pressurization curves," which were obtained under the slowest compression rate and at highest temperature. 

The difficulty of the experimental proof of the LLCP hypothesis, apart from the crystallization in NML, was that the amorphous ices were solid and not in the thermodynamical equilibrium. As for liquid, it was in the equilibrium and could be a sole state once pressure and temperature were fixed. Therefore, it would be possible to prove the discontinuity of the transition between two different liquids. However, regarding liquid water, LDL and HDL would crystallize immediately in NML, and we could not observe the LLT directly. In contrast, although we could observe the LDA HDA transition, the nonequilibrium nature of LDA and HDA threw doubt on the discontinuity of the transition logically. That is, the existence of the barrier in Fig. 5b was doubted the potential surface between LDA and HDA might be flat by nature. Then, the apparently discontinuous LDA-to-HDA transition (Fig. 7) might be, correctly, continuous or caused by unknown sticky relaxation of a nonequUibrium LDA state. If so, LLT of water would be continuous and LLCP would not exist. 

The combination of this knowledge and the results of quick-freezing processes provide a theoretical opportunity to freeze products into a solid, amorphous state. If the freezing velocity is smaller than required for vitrification, but large enough to avoid an equilibrium state, an amorphous mixture will result of hexagonal ice, concentrated solids and UFW. 

Cooling solutions to below their freezing point results in the formation of ice. If solutions of sugars are cooled rapidly, non-equilibrium ice formation occurs. This is the most common form of ice in frozen dairy products (e.g. ice-cream). Rapid freezing of ice-cream mixes results in the freeze concentration of lactose and other sugars, resulting in supersaturated solutions if the temperature is too low to permit crystallization. The rapid cooling of lactose results in the formation of a supersaturated, freeze-concentrated amorphous matrix. 

In particular for cryogenic amorphous phase of ice share of physical intermolecular /-bonds is negligible component. In such case formulas for equilibrium share sizes come to expressions ... 

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