Cellulose nitrate and acetate are materials at risk in heritage collections because it is not possible to predict the evolution of their conservation state over time. Knowing that the degree of substitution (DS) of these materials correlates with their state of conservation because the fundamental degradation mechanism is hydrolysis, in this work, DS was measured in historical objects and artworks. Infrared spectra were used to develop and optimize calibration curves for cellulose nitrate and acetate references that were next applied to calculate DS values of heritage objects. The extent of hydrolysis measured, with this tool, correlated well with the physical deterioration assessed through the sample hardness (Shore A) which was measured with a Durometer. Calibration curves were optimized in reference materials by Attenuated Total Reflectance (ATR-FTIR) and Micro Fourier Transform Infrared Spectroscopy (μFTIR). The DS values of the AC reference materials was previously calculated by nuclear magnetic resonance spectroscopy. The calibration curves were obtained plotting DS as a function of the ratio between a reference peak (which does not suffer relevant changes during degradation) and selected peaks that monitor the degradation for cellulose acetate and nitrate polymers (avoiding the interference of plasticizers). The reference peak for both was the COC stretching mode (νCOC). The probe peak was, for cellulose nitrate, the NO₂ asymmetric stretching (ν_aNO₂) and, for cellulose acetate, the OH stretching mode (νOH). This ratio was then applied to calculate DS values of historical materials, in good and poor conservation condition; in situ by ATR, and in micro-samples collected from artworks by μFTIR. This selection comprises cinematographic and photographic films dated from the 1890s to the 1960s, and contemporary works of art made with cellulose acetate sheets by Portuguese artist José Escada dated from the 1960s. Finally, by comparison with the original estimated DS values, we show how this tool permits to define the state of degradation of these complex polymer matrixes. Thus, establishing the quantification of the DS as a novel tool to monitor the degradation of cellulose ester plastics, contributing in this way for a sustainable preservation of an irreplaceable heritage.

This review summarizes the chemical composition reported up to date on Laurus nobilis L. (Lauraceae), an evergreen shrub or tree cultivated for its aromatic leaves and ornamental interest. It has been focused on non-volatile phytochemicals such as sesquiterpene lactones, flavonoids and proanthocyanidins, among others. Moreover, biological activities of laurel extracts and pure compounds have also been reviewed.

Anthocyanins are the basis of the color of angiosperms, 3-deoxyanthocyanins and sphagnorubin play the same role in mosses and ferns, and auronidins are responsible for the color in liverworts. In this study, the color system of cyanidin-3-O-glucoside (kuromanin) as a representative compound of simpler anthocyanins was fully characterized by stopped flow. This type of anthocyanin cannot confer significant color to plants without intra- or intermolecular interactions, complexation with metals or supramolecular structures as in Commelina communis. The anthocyanin’s color system was compared with those of 3-deoxyanthocyanins and riccionidin A, the aglycone of auronidins. The three systems follow the same sequence of chemical reactions, but the respective thermodynamics and kinetics are dramatically different.