Tannin-caprolactam and Tannin-PEG formulations as outdoor wood preservatives: weathering properties

Key message

This article presents the leaching, fire and weathering resistance improvements of samples treated with tannin-based wood preservatives added of caprolactam. PEG-added formulations show limited applicability. The FT-IR and ¹³ C-NMR analyses of the caprolactam-added formulations show some evidences of copolymerization.

Context

Tannin-boron wood preservatives are known for their high resistance against leaching, biological attacks, fire as well as for the good mechanical properties that they impart to wood. These properties promoted these formulations for being a candidate for the protection of green buildings. However, the low elasticity of these polymers and their dark colour implied limited weathering resistances.

Aims

The aim of the study is to find suitable additives for tannin-based formulations to overcome their limited weathering resistances, without compromising the other properties.

Methods

Treatment, leaching and fire tests, dimensional stability as well as artificial and natural weathering of the timber treated with caprolactam-added and PEG-added formulations were performed. FT-IR and ¹³C-NMR of the formulations were presented.

Results

The presence of caprolactam improved the properties of the formulation with particularly significant results in terms of resistance against leaching and dimensional stability. These enhancements were imparted also to the weathering resistance of the tannin-caprolactam formulations. Indeed, the colour changes during the artificial and natural exposures were stable for longer periods. FT-IR and ¹³C-NMR investigations of the advanced formulations were led, and covalent copolymerization of the caprolactam with the tannin-hexamine polymer was observed.

Conclusion

The tannin formulations with caprolactam improved the durability of the wood specimens, while the PEG-tannin presented strong application drawbacks.

     

Oxidative stress markers in canine atopic dermatitis

There are no data in the veterinary literature relating to oxidative stress in canine atopic dermatitis (CAD). The study aimed to determine levels of oxidative stress markers, plasma malondialdehyde (MDA), total antioxidant capacity (TAC), whole blood glutathione peroxidase (GPX) and erythrocyte superoxide dismutase (SOD), in 15 CAD patients and 17 healthy dogs. A correlation between CADESI (Canine Atopic Dermatitis Extent and Severity Index) score and MDA was also determined. Significantly higher plasma MDA levels were found in patients than in healthy dogs. The significant, highly positive correlation determined between CADESI score and MDA in the patient group indicates an association between the severity of CAD and the extent of oxidative damage to membrane lipids. There were no significant differences in TAC, GPX and SOD between patients and healthy dogs. Our findings suggest that oxidative stress with increased lipid peroxidation could be involved in the pathogenesis of atopic dermatitis in dogs.     

Factors Affecting Harvesting Intensity in Small-Scale Private Forests in Slovenia

Among other factors, harvesting intensity in private forests depends on property, resource and forest owner characteristics. The research was conducted in Slovenia, a Central European country with very fragmented and small-scale forest property, a large number of owners and co-owners and a long tradition of sustainable forest management. In the nationwide study, data from the Land and Property Register and forest inventory database were used to build a logistic regression model to identify factors that influence harvesting intensity. The results of the model revealed that growing stock, share of conifers, share of forest area under regeneration, total size of forest property in owner- and co-ownership, parcel size and accessibility of the forest area to forest operations increase harvesting intensity. Slope, number and age of owners and co-owners, and skidding distance negatively influence harvesting intensity. The results can offer useful information for policy and decision makers for formulating policy as well as implementing the most suitable mix of policy instruments.     

A Survey of Organotin Compounds in the Northern Adriatic Sea

The extent of pollution with organotin compounds was investigated in water, sediment and bivalve mussels (Mytilus galloprovincialis) from the Northern Adriatic Sea. Butyl-, phenyl- and octyltin species were quantified after extraction and derivatisation by gas chromatography–mass spectrometry in a total of 99 samples from the period from 2000 to 2006. The accuracies of the analytical procedures were checked by spiking of unpolluted water samples and by the analysis of standard reference materials (harbour sediment PACS-2 and mussel tissue ERM-CE 477). Among organotin species analysed in samples butyltins were the predominant. Tributyltin was found to be present in the highest concentrations, suggesting its recent input into the marine environment. Butyltins were detected at all sites surveyed (sum of butyltins was up to 718 ng Sn L^?1, 3,552 ng Sn g^?1 d.w. and 9,991 ng Sn g^?1 d.w. in water, sediment and mussel samples, respectively), phenytins in much lower concentrations (up to 31 ng Sn L^?1, 326 ng Sn g^?1 d.w. and 442 ng Sn g^?1 d.w. in water, sediment and mussel samples) and to a much smaller extent, while octyltins were not detected at any location. The spatial distribution of tributyltin was closely related to boating, with the highest concentrations found in marinas (up to 586 ng Sn L^?1 for water samples, 1,995 ng Sn g^?1 d.w. for sediment and 6,434 ng Sn g^?1 d.w. for mussel samples). The temporal distribution clearly indicates a decrease of organotin pollution at all sites.     

Rotenone and oxalic acid as alternative acaricidal treatments for Varroa destructor in honeybee colonies

This experiment assessed the efficacy of rotenone and oxalic acid (OA) in an aqueous sugar solution in controlling the honeybee mite Varroa destructor. Colonies were populated with mite-infested brood combs and worker bees. Three rotenone or OA treatments administered during the period with capped brood on 31 July, 14 and 18 August resulted in an average efficacy of 24.10%. In untreated colonies mite mortality averaged 5.40%. No significant differences (P>0.05) were found between the rotenone and OA treatments. Three OA treatments administered on 9, 12 and 18 September resulted in a 77.93% mite mortality. An increase in mite drop (P<0.05) was observed at 2 and 4 days after each treatment. OA applications in broodless colonies resulted in significantly (P<0.001) higher mite mortality rates (98.65% average) than the three treatments of rotenone or OA in colonies with capped brood. The dynamics of mite mortality after each rotenone or OA treatment are discussed in this study.     

Heat treatment and harvest date interact in their effect on superficial scald of ‘Granny Smith’ apple

A study was made of the effect of hot water dips (HWD) at temperatures of 42, 44, 46 and 48 °C (HWD 42 °C, HWD 44 °C, HWD 46 °C and HWD 48 °C, respectively) for 3 min on development of superficial scald and the concentration of α-farnesene and conjugated trienols (CT), CT₂₅₉, CT₂₆₉, CT₂₈₁, as well as OD₂₀₀ on Granny Smith apple fruits harvested on three dates and stored 125 days in air at 2 °C. HWD 48 °C efficiently decreased surface scald in the second and third harvest. α-Farnesene and CT were measured spectrophotometrically and by HPLC. No clear relationship of OD₂₀₀ and scald development was observed. Correlation of scald index and OD₂₀₀ at the end of storage was negative for the second harvest date. There was no significant correlation between the scald index and CT₂₅₉. Scald index was positively correlated with CT₂₆₉ after 80 days for the second and third harvest and at the end of storage for the second harvest. CT₂₈₁ was spectrophotometrically detectable only at the end of the storage, for the third harvest date, in control, HWD 42 °C, and HWD 44 °C. HWD 42 °C had significantly higher CT₂₈₁ compared to HWD 44 °C and control. HPLC analysis of control samples revealed presence of CT₂₈₁ in all three harvest dates, and presence of at least two components, as was the case of CT₂₅₉ and CT₂₆₉. The ratio of these two components was different for all three CT species. Fruit maturity was an important factor determining the response of fruit to heat and occurrence of superficial scald. The results indicate that a successful treatment using HWD to control superficial scald may be obtained after further research and that there are still some questions on the role of different CT's in scald biochemistry that should be addressed in future research.