Dehydration of raffinose pentahydrate: structures of raffinose 5-, 4.433-, 4.289- and 4.127-hydrate at 93 K.

Raffinose [or O-α-D-galactopyranosyl-(1→6)-α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside] pentahydrate, C18H32O16·5H2O, (I), and three lower hydrates, namely the 4.433-, (II), 4.289-, (III), and 4.

Freeze-thaw behaviour of aqueous glucose solutions--the crystallisation of cubic ice.

We report on the polymorphic transitions of ice in aqueous solutions of glucose during freezing and thawing over a temperature range of 298-153 K. Emphasis is placed on the sub-glass temperature range where the systems consist of cubic ice (ice-1c) crystals embedded in a freeze concentrated, vitrified glucose solution. The systems were studied by a combination of thermal, cryomicroscopic and X-ray diffraction techniques.

Cubic ice can be formed directly in the water phase of vitrified aqueous solutions.

This study addresses the possibility that ice-Ic may form spontaneously and directly during the cooling of previously freeze-concentrated aqueous solutions, at temperatures where the residual unfrozen water is likely to exist in small, isolated domains. It is shown that on cooling a dilute aqueous glucose solution, ice-Ih crystallises initially, but when the solution has been freeze-concentrated to ca.10 mol %, further cooling results in the slow nucleation and growth of ice-Ic in the residual water domains, rather than on the pre-existing ice-Ih crystal surfaces.

Current topics on sample preservation. A report on the progress of the ESA Topical Team. Preservation of fixed and non-fixed samples during space experimentation.

The existence of preservation problems is one of the most important consequences of Space Biological Research. The Topical Team is critically analyzing the currently performed procedures and is establishing the bases for a recommendation on new procedures, capable of overcoming the present constraints.

Scientific and technological aspects of aqueous glasses.

The physical nature of a glass, as related to stable liquid and crystalline solid phases was defined by Kauzmann in 1948. Since then, glass research has been almost exclusively confined to inorganic materials. This review aims to demonstrate that many substances, not falling into the category of classical 'materials', can be rendered into amorphous states.

Nucleation of ice and its management in ecosystems.

In addition to the gas and liquid phases, water can exist in many different solid states. Some of these are the well-studied crystalline ice polymorphs and the clathrate hydrates, but at least two distinguishable amorphous solid forms have also been shown to exist. This diversity of possible condensed states implies a multiplicity of transitions, each of them presumably associated with a nucleation step.

Protein stability: the value of 'old literature'.

The concepts of protein structure and function have been subjects of intensive study throughout the 20th century; they continue to fascinate present-day scientists. Our understanding received a major boost when it was realised during the 1960s, that the physical properties of water play a major role in determining the stability of native proteins in vitro. This recognition changed the emphasis of physicochemical studies towards 'hydration', i.