Benedetto Pizzo

A New Method to Quantitatively Evaluate the Chemical Composition of Waterlogged Wood by Means of Attenuated Total Reflectance Fourier Transform Infrared (ATR FT-IR) Measurements Carried Out on Wet Material

Wood degradation in waterlogged conditions, although slow, is relevant in some specific contexts, such as in the case of cultural heritage preservation (e.g., ancient shipwrecks found under the water table). This decay process induces the selective depletion of the biopolymers constituting wood cell walls and mainly of their structural polysaccharides (both cellulose and hemicelluloses). Assessment of residual composition of cell walls is normally carried out using conventional chemical analyses, which, however, require elevated amounts of material. The present work reports on a new approach to quantitatively determine the residual chemical composition of wood (in terms of amount of lignin and holocellulose) and therefore its extent of degradation. This was accomplished by acquiring attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectra on material still in waterlogged conditions, which was simply placed in optical contact with the ATR crystal. Data for the calibration set were obtained by means of wet analyses, and the calibration model was based on multivariate statistical analysis through partial least square regression. Acquired spectra showed signals higher and better resolved than for dry wood. Calibration was selected after comparing two different normalization procedures and after processing signals of two different spectral ranges. Furthermore, the exclusion of some outliers led to a substantial improvement in the error parameters (R2 and root mean square error of cross validation) associated with the calibration model, thus allowing for the selection of the best model. The stability of this best model was also established by means of the leave-more-out method. Finally, a procedure of external validation confirmed that the proposed model also could be applied to similar (for instance, belonging to Pinaceae) wood remains from other excavations.

Durability of five native Argentine wood species of the genera Prosopis and Acacia decayed by rot fungi and its relationship with extractive content.

The natural durability of four Argentinean species of Prosopis and one of Acacia was evaluated in laboratory tests, according to European standards, using three brown rot and one white rot fungi. These tests were complemented by assessing the wood chemical composition. All the species were from moderately slightly durable to very durable (classes 4–1), and in all cases the heartwood was the most resistant to fungal attack. Chemical extractives content (organic, aqueous, tannic and phenolic) was higher in the heartwood. However, species durability was not related to extractive contents nor with wood density. Instead, it is possible that extractives could contribute to natural durability in different ways, including the effects related to the antioxidant properties of some of them.

Characterization of Waterlogged Wood by Infrared Spectroscopy

The work concerns the characterisation of waterlogged archaeological wood samples from different excavation sites in Italy by means of infrared spectroscopy. It describes some preliminary evaluations of the analyses carried out, including a quantitative estimation of the holocellulose, one of the structural chemical components constituting the cell walls.

Dynamic mechanical analysis (DMA) of waterlogged archaeological wood at room temperature

Abstract The viscoelastic properties of waterlogged wood (WLW) were investigated via dynamic mechanical analysis (DMA) at room temperature and under water saturated conditions, aiming at the investigation of the relationships between viscoelasticity and chemical composition. Different softwoods (SWs) and hardwoods (HWs) from several archaeological sites were sampled, which had different levels of decay (from highly-decayed to little changed). The analytical methods included lignin and holocellulose determination by Fourier transform infrared (FTIR) spectroscopy, moisture content (MC), basic density (BD), micromorphological observations, and the DMA was performed in three-point bending and submersion mode. Both HWs and SWs showed an exponential decrease of both storage modulus (E′) and loss modulus (E″), which are related to the amount of crystalline and paracrystalline cellulose left in the cell wall, respectively. The ratio E″/E′ (tanδ) varied with the frequency in different ways depending on the preservation state of the samples. Less decayed material had a higher tanδ than the fresh reference wood and lower (or similar) tanδ in the case of highly decayed samples. Accordingly, the long-term behaviour under a certain sustained load of WLW is decay dependent.

Nutritional requirements for larval development of the dry wood borer Trichoferus holosericeus (Rossi) in laboratory cultures

Despite the dangerousness of the dry wood-boring beetle Trichoferus holosericeus (Rossi) (=Hesperophanes cinereus (Villiers)) (Coleoptera: Cerambycidae), little is known about its biological and nutritional requirements. The aim of this research was therefore to investigate into the dietary preferences of this insect, in order to determine if carbohydrates can be considered as its main nutritional source, to clarify whether this cerambycid is specialised on hardwoods and finally to select a suitable diet for laboratory cultures. Different substrates were tested and the decay grade, as well as the survival of larvae, was recorded after 3 and 6 months. Chemical analyses were also carried out on excrements, residues of wood after larvae excavation and sound wood. Results indicated that T. holosericeus fed mainly on glucose and peptone added to an artificial diet, while on natural wood it preferred structural carbohydrates constituting the hemicelluloses and the non-crystalline cellulose. Furthermore, Scots pine sapwood had no toxic effect to the beetle. In terms of number and dimensions of emerged larvae, the artificial diet resulted to be the most suitable substrate for laboratory cultures of T. holosericeus among those tested.

Understanding Spanish Timber Jack Arch Floors: Examples of Assessment and Conservation Issues

Jack arch floors are structures made of timber joists, with round or squared section, and segmental vaults either made of flat tiles or poured plaster conglomerate. They are especially diffused along the Mediterranean coast of Spain and can be considered as a main feature of the historical and vernacular architecture of the area. In order to assess and grade these structures several Spanish standards have been considered; however, even if the information contained is useful the Italian standard for the on-site diagnosis UNI 11119 of 2004 has been preferred. The method described in this standard leads the assessment through the grading of each and every timber element and the assignation of bearing properties that are essential for the consolidation project. This article will expose three examples of jack arch floors of the Valencian Community graded using the Italian standard and the conservation issues that arise from the results.

Preserving Archaeological Remains In Situ: Three Case Studies in Trentino, Italy

Abstract The paper presents the results of the restoration and conservation work which has been carried out in three archaeological areas in the Autonomous Province of Trento. The areas, which have been opened to the public for more than ten years, are the open-air archaeological site of Monte S. Martino, Roman Tridentum (an underground site under the historical city centre of Trento), and Fiavé (a pile dwelling site in a peat bog). These areas present very different environmental characteristics and have therefore required different interventions according to their specific situation. In order to reduce maintenance and extraordinary costs, appropriate conservation of the archaeological remains is required. This consists of methodologies of conservation according to the characteristics of the environment; continuous monitoring systems and indirect preventive intervention; and annual maintenance planning.