The Effects of Freeze-Drying on the Strength Characteristics of Naturally Aged Book Papers

Libraries occasionally have water main breaks, fires and floods. These disasters cause considerable water damage to thousands of books. Books that are left wet on the shelves will grow mold. Books that are quickly frozen and eventually freeze-dried can be restored to the shelf in good condition. Several libraries have used freeze-drying for this purpose and have had great success. Freeze-drying is a process used to remove frozen liquid from a substance. The moist material is frozen and put in a vacuum. A high vacuum with some heat introduced will cause the frozen liquid to sublime. A dry-porous structure is left behind. There has been no test data found considering the effects of freeze-drying on the strength of papers. The purpose of this report is to examine this process. Eleven books up to 173 years old were wetted and freeze-dried. Some cockling of papers were observed. Strength properties of fold, tensile and zero span tensile essentially remained unchanged. Freeze-drying, in respect to the relatively small number of samples tested, does not have any detrimental effect on the strength of paper. Freeze-drying is recommended for restoration of water damaged books

Regulation of G(0) entry by the Pho80–Pho85 cyclin–CDK complex

Eukaryotic cell proliferation is controlled by growth factors and essential nutrients. In their absence, cells may enter into a quiescent state (G(0)). In Saccharomyces cerevisiae, the conserved protein kinase A (PKA) and rapamycin-sensitive TOR (TORC1) pathways antagonize G(0) entry in response to carbon and/or nitrogen availability primarily by inhibiting the PAS kinase Rim15 function. Here, we show that the phosphate-sensing Pho80–Pho85 cyclin–cyclin-dependent kinase (CDK) complex also participates in Rim15 inhibition through direct phosphorylation, thereby effectively sequestering Rim15 in the cytoplasm via its association with 14-3-3 proteins. Inactivation of either Pho80–Pho85 or TORC1 causes dephosphorylation of the 14-3-3-binding site in Rim15, thus enabling nuclear import of Rim15 and induction of the Rim15-controlled G(0) program. Importantly, we also show that Pho80–Pho85 and TORC1 converge on a single amino acid in Rim15. Thus, Rim15 plays a key role in G(0) entry through its ability to integrate signaling from the PKA, TORC1, and Pho80–Pho85 pathways