Freezing future research

Polymers such as dextrans could provide many desirable properties (e.g., high 7g and T ) to the freeze-dried formulation. Therefore, it is essential that future research address the theoretical and practical aspects of protein/polymer phase separation and develop the mechanistic insight to prevent this phenomenon during lyophilization. Also, as part of this effort, it is important to discern why other polymers (e.g., PVP and BSA) that protect labile proteins apparently do not phase-separate from the protein during lyophilization. 

The conservation experiments required books uniformly damaged by flood water. A simulated flood, drainage, and book-freezing sequence was developed so that it would be applied to these two groups of books resulting in a minimal variation in damage. The composition of the uncoated and the coated paper was held basically constant in these studies. Future extension of this research effort should consider varying... 

Consequently, a common effort should be made to establish and complete the data basis concerning the numerous thermodynamic, thermophysical, transport and rheological properties necessary for modeling and simulating the different steps of this complex mild drying process. Moreover, the methods available for the characterization of most of these end-use properties should be improved and additional characterization methods should be adapted from other research fields (material science, applied biochemistry, physical chemistry, etc.). Improved characterization methods promise a better description and a safer control of numerous end-use properties for existing freeze-dryers as well as for new machines with more possibilities to better comply with more and more severe quality requirements in the future. The use of non-invasive sensors or of rapid non-intrusive methods for on-line and in situ estimation of the main parameters of the process could also help to overcome the difficulties observed, for example, the artifacts resulting from invasive sensors inserted inside vials and presently commonly used. 

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