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An analysis in terms of elastic scans of the neutron intensity of homologous disaccharide (trehalose, maltose, sucrose)/H[sub 2]O mixtures as a function of temperature and exchanged wave vector has been carried out. The experimental findings, showing a crossover in molecular fluctuations between harmonic and anharmonic dynamical regimes, allow us to characterize the system “flexibility.” A new operative definition for the “fragility” degree, by using elastic incoherent neutron scattering, is furnished. In this frame the lower flexibility and fragility character of trehalose/H[sub 2]O mixture with respect to maltose and sucrose/H[sub 2]O mixtures indicate a better attitude to encapsulate biostructures in more rigid and temperature insensitive structures in approaching the glass transition. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We will consider the use of the bond model in characterizing, by the direct calculation route, the full excitation profile. The present work sets the temperature behaviour of the excessive value of some thermodynamic quantities, such as configurational entropy and heat capacity of two homologous disaccharide aqueous solutions. The findings represent important data for understanding the better lyoprotectant effectiveness of trehalose in comparison with sucrose. [ABSTRACT FROM AUTHOR]

Neutron incoherent elastic scattering data have been collected on homologues disaccharides (trehalose, maltose, sucrose)/H2O mixtures as a function of temperature. The results show a dynamical transition at T∼238 K, T∼235 K and T∼233 K for trehalose, maltose and sucrose/H2O mixtures, respectively, marking a cross-over in molecular fluctuations between harmonic and non-harmonic dynamical regimes, proving a higher ‘rigidity’ of trehalose mixture with respect to maltose and sucrose mixtures. This finding accounts for the higher cryptobiotic effectiveness of trehalose, namely a capability to encapsulate biostructures in a more rigid environment. [Copyright &y& Elsevier]