Sabrina Palanti

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.

Copper complexes grafted to functionalized silica gel as wood preservatives against the brown rot fungus Coniophora puteana

Wood modification with siloxanes bearing amino groups with copper-linking function was carried out by a sol–gel process. Tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) were the main components. Two different procedures were followed: a two-step process (impregnation with the TEOS/APTES mixture followed by dipping into a copper sulphate solution) and a one-step process (impregnation with a homogeneous sol mixture of TEOS, APTES and copper (II) chloride). The obtained materials were characterized by infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis. The determination of copper content before and after leaching was performed by atomic absorption spectroscopy. The efficacy against the brown rot fungus Coniophora puteana was tested by an accelerated procedure. SEM analyses showed that silicon penetrated into wood, while copper is effectively drawn into wood only in the one-step treatment. Copper fixation to the silica gel proved to be adequately strong. Both sol–gel treatments gave good protection against Coniophora puteana.

Polyamidoamines (PAAs) functionalized with siloxanes as wood preservatives against fungi and insects

Abstract A novel treatment based on polyamidoamines (PAAs) for the preservation of wood against fungi and insects with a broad protection functionality, low effective concentration, and low environmental impact has been developed. PAAs were synthesized by nucleophile addition of ethanolamine (EtA) and/or 3-aminopropyltriethoxysilane (APTES) to N,N′-methylene-bisacrylamide (MBA). The molar ratios in the tested formulation were: I) MBA:EtA=1:1; II) MBA:APTES=1:1; III) MBA:EtA:APTES=1:0.5:0.5. These formulations, characterized by ESI-MS, NMR, FT-IR, were tested against: (a) the wood decay fungi (Coniophora puteana, Coriolus versicolor, and Poria placenta); (b) the subterranean termite Reticulitermes lucifugus, and the drywood termite Kalotermes flavicollis; (c) the woodborer Stegobium paniceum. Tests in combination with leaching showed that formulation II and III can be utilized as fungal wood preservatives for use classes 2–3 (EN 335:2013). In addition, all PAAs formulations were equally effective in preserving wood against the subterranean termite, and formulation II was most effective against drywood termite. On the other hand, the formulation I showed good efficacy against S. paniceum.

Diagnostic Evaluation of Insect Attack on Existing Timber Structures: A Review of some Case Studies

The problem of wood-boring insect attacks is gaining greater interest in Italy today. Wood-boring insects (Coleoptera, termites) often cause both structural and aesthetic damage on wooden structures which can sometimes give rise to human health concerns. Possible causes of current insect infestations include the use of timber originating from plantations, as well as bad post-felling practices such as late harvesting and stocking in unsuitable places before final processing. In the past, these insects were not thought to pose an economic threat to timber in service in Italy, but, in recent years, they have become a problem. The aim of this paper is to report on case studies concerning the occurrence of these unusual wood-boring insects on timber in service and, on the basis of the Authors experience, to formulate an in situ inspection protocol. The species we are dealing with in the case studies are: Bostrichus capucinus, family Bostrichidae, associated with Lyctus spp. (Fam. Lyctidae) and Lymexylon navale, family Lymexylonidae, belonging to the group of the so-called ambrosia beetles or pinhole borers. All these species were found on hardwoods, where they had bored into the sapwood except for L. navale which was also able to bore into heartwood, causing major concerns about its potential danger to timber in service. A technical integrated approach in evaluating insect attacks on on-site timber elements is also described here. The assessment is based on different methods, i.e. visual inspection and acoustic detection. This procedure is proposed as a basis for the development of an intervention protocol in the early stages of infestation.

Microwave Reflectometric Tool for Non-Destructive Assessment of Decay on Timber Structures

Timber structures can be degraded during their life both by structural problems and, mainly, by biological degradation factors like fungi, and insects (Coleoptera and termites). The occurrence of these biodegradation agents leads, in the absence of appropriate maintenance interventions, to the loss of their structural integrity. Furthermore, if these biological agents decay old buildings, the loss of mechanical resistance of timber structures can be added to loss of cultural heritages. Just in these contexts an early evaluation of decay is crucial to design remedial treatments and a less invasive restoration intervention. This work presents a new microwave diagnostic system for the in situ evaluation of timber structures based on microwave reflectometry, i.e on the measurement of the microwave reflection coefficient as a function of frequency. The continuous-wave (CW) microwave signal is launched by a double-ridged antenna, which also measures the wave reflected by the material under investigation. The measurement system allows diagnosing the effects of biodegradation during a first quick survey in a non-destructive and non-invasive manner. Measurements on laboratory models demonstrated the feasibility of the method. Results obtained on timber beam sections, compared with the findings of traditional investigation methodologies, demonstrate the potentiality of microwave reflectometry, suggesting its usefulness for decay detection and as a support to invasive diagnostic tools.

Enzymatic grafting of kraft lignin as a wood bio-protection strategy. Part 1: factors affecting the process

Abstract Kraft lignin (KL) isolated from the black liquor of pulping has some antifungal potential. For investigation of this effect, KL was treated with laccase to form covalent bonds to green wood and the critical parameters for enzymatic grafting have been evaluated. The biocidal properties of KL could be confirmed. Growth inhibition of over 50% was found with lignin concentrations equal to or higher than 10 g l−1. The change of wood color was evaluated based on the CIEL*a*b* color system and the data served for evaluation of the effectiveness of the KL binding to wood. The grafting reaction time was the most important variable in the impregnation process. Significant degrees of grafting were achieved in 10 min when samples were left to air dry after impregnation. The color loss was 30% after wood extraction with acetone. Higher temperatures and enzymatic pre-activation did not have a significant effect. As a conclusion, the most suitable procedure for enzymatic grafting of KL onto wood is by air-drying of the impregnated materials.

Enzymatic grafting of kraft lignin as a wood bio-protection strategy. Part 2: effectiveness against wood destroying basidiomycetes. Effect of copper entrapment

Abstract Enzymatic grafting of kraft lignin (KL) on wood surfaces is presented as a non-leachable wood protection treatment. Scots pine and European beech mini-blocks were treated with KL solution in the presence of laccase isolated from Myceliophthora thermophila and the formation of a stable interaction between wood and lignin was observed. Furthermore, the same strategy was employed to graft KL with the simultaneous entrapment of copper in the polymeric net formed. Enzymatic treatment diminished the leachability of the compounds in accordance with the EN 84 standard. The durability of the leached wood blocks was evaluated by accelerated decay tests. Samples with grafted lignin on the surface lost their antifungal activity in long-term exposure at the concentration tested. This observation is in contradiction to the preliminary tests, where KL seemed to have some biocidal activity. On the other hand, KL grafting in combination with copper entrapment improved the decay resistance and the copper leaching was reduced.

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.

First Trials for a Microwave Reflectometric Tool to Survey Decay in Historic Timber Structures

Timber structures can be degraded during their life both by structural problems and by biological degradation factors like fungi, and insects. The occurrence of those biodegradation agents could lead to a loss of their structural integrity, in the absence of appropriate maintenance. An early assessment of the decay is even more important when the wooden structures are part of historical buildings, in the interest of conservation of cultural heritage. This work presents an application of microwave reflectometry for the in situ evaluation of timber structures. The measurement system allows detecting anomalies inside the material in a non-destructive and non-invasive manner. The reflection coefficient is measured by means of a vector network analyzer (VNA) using a double-ridge antenna, which transmits the continuous-wave microwave signal and receives the signal reflected by the material under investigation. Measurements on laboratory models demonstrated the feasibility of the method. Results obtained on timber beam sections, compared with the findings of traditional investigation methodologies, demonstrate the potentiality of microwave reflectometry, suggesting its possible usefulness during the diagnostic phase as a non-invasive tool for preliminary screening.

Trattamenti sostenibili per la protezione e il consolidamento di legno e carta

LAURA BERGAMONTIA, CLAUDIA GRAIFFA, CLELIA ISCAA, GIOVANNI PREDIERIA*, PIER PAOLO LOTTICIB, ROSA DI MAGGIOC, SABRINA PALANTID, LARA MAISTRELLOE, MATTEO MONTANARIF ADIPARTIMENTO DI SCIENZE CHIMICHE, DELLA VITA E DELLA SOSTENIBILITÀ AMBIENTALE, UNIVERSITÀ DI PARMA BDIPARTIMENTO DI SCIENZE MATEMATICHE, FISICHE E INFORMATICHE, UNIVERSITÀ DI PARMA CDIPARTIMENTO DI INGEGNERIA CIVILE, AMBIENTALE E MECCANICA, UNIVERSITÀ DI TRENTO DISTITUTO PER LA VALORIZZAZIONE DEL LEGNO E DELLE SPECIE ARBOREE, CNR-IVALSA, FIRENZE EDIPARTIMENTO DI SCIENZE DELLA VITA, UNIVERSITÀ DI MODENA E REGGIO EMILIA FBIORES LAB, BOLOGNA GIOVANNI.PREDIERI@UNIPR.IT