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Soil-bed studies (Part 3): A cause of failure of multisalt preservatives following soil-bed exposure
1983 - IRG/WP 3261
P Vinden, J F Levy, D J Dickinson

Lignin-copper, a new wood preservative without arsenic and chromium
1992 - IRG/WP 92-3702
A more environmentally sound treatment for wood with preservatives containing no arsenic or chromium, has been developed and studied on a laboratory scale. The method involves a first step impregnation with an aqueous solution containing modified, water-soluble kraft lignin followed by a second step involving impregnation with a copper salt solution to give fixation of the lignin into a water-insoluble form and to achieve complementary protection. The two steps can be performed without intermediate drying of the wood in a conventional reactor for vacuum-pressure impregnation. The treatment has been shown to give good protection against degrading fungi, tunnelling bacteria and termites, and a lower growth of mould on the wood surface. Field tests (NTR test) indicate, after 4 years of exposure, very good protection gained by this new treatment. Fibre and particle boards made from wood fibres and wood particles, treated with this method show increased dimensional stability and rot resistance.
B Ohlsson, R Simonson

Sterilization of mango wood (Mangifera indica L.) without heat
1995 - IRG/WP 95-30065
Researches revealed that boric acid can play an important role for sterilizing wood instead of heating. Wet (green) mango boards (Mangifera indica L.) were pressure treated in treating cylinder at initial vacuum of 508 mm Hg for 15 minutes and impregnation pressure of 7 kg/cm² for 4 hours with 5% solution (w/v) of 1:1:1 commercial grade (95% pure) sodium dichromate, copper sulphate and boric acid. Penetratons of copper sulphate and boric acid were examined by using standard reagents. Copper sulphate penetrated superficially but boric acid penetrated completely through the boards. In most hazardous conditions during rainy season the treated boards were saved like heatsterilized boards from the attack of decay fungi and insects. Untreated boards (control) were found decayed and damaged within three months with the decrease of strength significantly. Where heatsterilization and kiln-drying are practically impossible during rainy season, wet timbers can be stored after impregnating those with at least 2% solution (w/v) of boric acid which diffuses through wet wood successfully and can protect wood from decay fungi, and wood destroying borers.
A K Lahiry

Effects of cyproconazole and copper sulphate on the length of the hyphal growth unit (HGU) of the white-rot fungus Coriolus versicolor
2003 - IRG/WP 03-10473
Wood decay basidiomycetes have been shown to produce appreciable quantities of extracellular mucilaginous materials (ECMM). The relationship between ECMM and total biomass production has been investigated in the white-rot fungus Coriolus versicolor (CTB 863 A). Differences in the amount of ECMM produced by the fungus proportionally to the total biomass, were observed under a range of physiological conditions, including the presence of biocides. Such differences suggest that stress may have a role in stimulating an increase in the amount of ECMM produced by C. versicolor. The rationale behind this study is that the increase in the proportional amount of ECMM produced by the organism under a range of different stress conditions, may be explained by the hypothesis of the Hyphal Growth Unit length (HGU). The results presented in this paper support the hypothesis that the length of the HGU is strongly related to the environmental conditions. Cyproconazole at 0.1 mmols l-1 in the growth medium, reduced total biomass by approximately 50% and decreased the length of the HGU by approximately 50%. This change in the HGU length reflects a change in the hyphal behaviour to a highly brached mycelial habit. Associated with this was a 100% increase in the proportion of ECMM in relation to the hyphal biomass. Since ECMM is known to be secreted at the tip of actively growing hyphae, it is hypothesised that by adjusting the length of the HGU, filamentous fungi are able to produce a highly branched mycelium, which leads to the production of high levels of ECMM. This could offer protection against adverse environmental conditions, such as the presence of biocides. These results are discussed with regard to the possible role(s) of ECMM in the decay process and its interaction with preservative treatments.
D Vesentini, D J Dickinson, R J Murphy

Preservative treatment of wood by diffusion processes - Simulation of commercial treatment processes
1988 - IRG/WP 3498
Spruce (Picea abies), Scots pine (Pinus sylvestris) and birch (Betula pendula) were preservative treated by diffusion with mixtures of copper sulphate and arsenic pentoxide. The preservative was fixed after a suitable diffusion storage period by soaking in ammonia solution. A high standard of treatment could be achieved in spruce sapwood. This was attributed to its low wood density, and high wood moisture content. The variable treatability of spruce heartwood and poor treatability of Scots pine heartwood was related directly to their moisture-content. Complete preservative penetration could be achieved in spruce heartwood when moisture contents were 60% or above whereas Scots pine heartwood with a fresh moisture content of 30% was untreatable by diffusion. Preservative penetration was directly related to preservative retention and immobilisation by fixation. This was demonstrated clearly for birch which because of its high basic wood density tended to immobilise a greater quantity of preservative salt per unit volume. The effects of preservative retention and diffusion storage time on the subsequent distribution of preservative was determined for Pinus ponderosa. The relationships established can be used for defining suitable diffusion treatment schedules.
P Vinden

Persistance of active ingredients in treated wood
1993 - IRG/WP 93-50001-20
Disposing of chemically protected waste wood implies the distinction between surface and pressure treatment. Considering that barked round-wood merely contains, after 7 months open storage, less than 30 g per ton of bark or 25 mg per ton of sapwood, depending on the type of insecticide, the bark or sapwood shavings may be incinerated normally, according to less severe legal prescriptions than for pressure treated wood. Past use poles, destroyed by fungi, will indeed have to be disposed of in specially equipped incineration plants, which respond to strict requirements regarding the waste air.
E Graf, P Manser, S Rezzonico, B Zgraggen

Accelerated diffusion treatment of sawn Sitka spruce grown in the UK
1986 - IRG/WP 3395
The treatment of 'green' sapwood and heartwood of Sitka spruce by diffusion methods was investigated. Steam/dip treatment processes gave increased solution uptakes and depths of penetration of copper in comparison with a simple dip treatment. Further investigation is required to reduce diffusion gradients with copper based formulations and to improve the penetration of 'green' heartwood of Sitka spruce by diffusion methods.
R J Murphy, D J Dickinson

Dimensional stabilization and decay resistance of wood treated with brown-rotted lignin and copper sulfate
1990 - IRG/WP 3608
The objective of this study was to evaluate the potential usefulness of brown-rotted lignin (BRL) as a dimensional stabilization and copper complexing agent for wood treatment. For dimensional stabilization, aqueous solutions of the lignin extract were combined with either copper sulfate, glyoxal or other additives. Anti-shrink efficiency (ASE) values as high as 42% were obtained with wood treated with a BRL/Cu combination. By treating wood with a 6% solution of the lignin extract prior to treatment with copper sulfate, a two-fold increase in fixation of copper was attained. Soil block tests were also performed on wood treated with BRL and copper sulfate individually as well as in combination; it was found that the BRL increased the activity of Cu against Poria placenta.
L Jin, D D Nicholas, T Schultz

Fungicidal effectiveness of amended alkylammonium compound
1987 - IRG/WP 3421
Amendment of didecyldimethylammonium chloride was attempted to improve its fungicidal effectiveness and properties of treating solutions. Addition of copper definitely increased effectiveness in controlling wood decay fungi, although metal corrosiveness and stability of treating solutions was unsatisfactory. Further amendment with stabilizer(s), anticorrosive agent(s) and sequestering agent(s) resulted in improving fungicidal effectiveness as well as properties of treating solutions. When a wood block was impregnated with an adequate mixture of didecyldimethylammonium chloride, copper sulphate, sequestering agent, stabilizer and anticorrosive agent (1:0.5:0.5:1:0.25), laboratory test (JIS A 93029) indicated that a lower retention level of didecyldimethylammonium chloride (1.1 kg/m³) gave a satisfactory protection to the block from decay fungi. On the other hand, didecyldimethylammonium chloride itself was effective enough at higher retentions of 2.2-4.3 kg/m³.
K Tsunoda, K Nishimoto

Studies of the mechanism of chromated-copper preservative. Fixation using electron spin resonance
1992 - IRG/WP 92-3701
Two softwoods and one hardwood species were treated with chromium trioxide, copper sulphate, chromated-copper wood preservative (CCA). The treated wood samples were analyzed during fixation by electron spin resonance (ESR). ESR spectra indicated that more than one Cr(V) species was generated from Cr(VI) soon after CCA treatment. The Cr(V) signal became strong within increased several hours followed by the gradual decay of Cr(V) accompanying with generation of single broad Cr(III) species. Cr(V) signal still remained at least up to six months after the treatment. ESR spectral parameters from Cu(II) signal consisted of a quadruplet at lower field with a unresolved absorption of higher field, suggesting a evidence of a dX²-Y² ground state of Cu2+ ions bound in inner-sphare complexes with "O4" ("O6") ligands arranged in square planar cordination (distorted octahedral) cordination. Cu(II) signal did not change significantly during fixation.
K Yamamoto, J N R Ruddick

Copper based water-borne preservatives: Copper adsorption in relation to performance against soft rot
1987 - IRG/WP 3452
As part of a fundamental study concerned with the performance of copper based water-borne preservatives the adsorption of copper from aqueous solutions by 4 hardwood and 1 softwood species has been studied. Experiments were conducted to determine the influence of solution pH, solution concentration and solution temperature. The results obtained were consistent with an acid form ion-exchange mechanism for copper adsorption. These properties of water-borne preservative solutions containing copper are discussed in relation to hardwood performance against soft rot decay.
P M S Rennie, S M Gray, D J Dickinson

Preservative treatment of green timber by soaking in ammoniacal copper borate
1984 - IRG/WP 3292
Freshly sawn boards of radiata pine sapwood were preservative treated by soaking in ammoniacal copper borate. Optimum schedules were obtained by partially seasoning the boards for one week prior to treatment. This aided the absorption of preservative and reduced the required soaking time to approximately 2 hours. Complete boron penetration was obtained after one week of block storage under cover and air drying. Copper penetration was more limited because of fixation of copper. The preservative treatment system should have particular application in the treatment of coconut timber destined for above-ground use but exposed to the weather.
P Vinden, A J McQuire

On the use of probit analysis for assessing the toxicity of wood preservatives
1974 - IRG/WP 244
To elucidate the general character of the action of the toxic material on the fungus, it is sufficient to carry out preservative tests using the previously described procedure, but in doing so, it is necessary somewhat to change the number of specimens and their arrangement in jars. Five concentrations of toxic material are tested simultaneously. For the testing of one preservative ten jars should be used in each of which are placed 50 specimens, comprising 10 of each of the five concentrations. The proposed arrangement of the specimens in jars makes due allowance both for the variation in the reaction of the individual sections of the mycelium in one jar (ten specimens) and for the variation in the reaction of the fungus in the different jars (ten groups of specimens). The effect of each concentration of toxic material on the fungus may, therefore, be assessed from the result of observing its reaction on a hundred specimens tested in all ten jars. With this procedure the author investigated the toxicity to Coniophora of sodium fluoride, sodium chloride and sodium silicofluoride, copper sulphate, zinc chloride, ammonium fluoride and ammonium pentaborate. The results are given in Table 1. Complete curves of the toxic effect were not obtained for all the formulations, but for the majority of them levels of transition from incomplete to practically complete protection of the timber against destruction by the fungus were established. The test results for sodium fluoride, using the given procedure, are represented graphically in Fig.1 (curve 2). It can be seen from Fig.1 that the change of reaction of Coniophora in timber containing different amounts of NaF is well described by an S-shaped curve, similar to the integral function of a normal distribution. Similar graphs are also obtained when testing other preservatives. The nature of the curve shows yet again that different probit-analysis methods may be used when testing preservatives in timber. Fig.3 shows the probit curves of the effect of sodium fluoride. Since in our case the curve is symmetrical and not lengthy, there was no need to use a logarithmic scale for the axis of abscissae. It can be seen from Fig.3 that, by using a normal distribution as a model for transforming the NaF toxic effect curve, rectilinear graphs are obtained. With such graphs it is easy to find the different levels of timber protection, and also to assess the variation of the reaction of the wood-destroying fungus by computing the mean dose and the standard deviation by the known methods of probit-analysis. From the probit v. NaF content graph (Fig.3) is found the amount of sodium fluoride necessary for protecting the timber of pine sapwood against destruction by Coniophora in 95 per cent of cases. It is 0.168 kg/m³. When determining the said level of protection by the author's proposed procedure, the value obtained was 0.136 kg/m³, i.e. 0.032 kg/m³ less. This is due to the fact that in the latter case the number of specimens tested was comparatively small. The proposed method, therefore, gives an overall picture of the protection of the timber by a specific preservative against the action of wood-destroying fungus and enables the amount of toxic material, which should be selected for a more detailed investigation by the previously reported procedure, to be determined.
D A Belenkov

Investigation of copper fixation in timber by sodium nitrit
1992 - IRG/WP 92-3707
Solutions containing mixtures of water soluble copper salts and sodium nitrite have been shown to be capable of producing leach resistant copper treatments when impregnated into timber. A rapid leaching trial showed that copper fixation levels of 85-90% were possible which compared well with the fixation level obtained with conventional hexavelant chromium containing systems in the same test regime. The fixation process appears to be dependant only upon the presence of copper and nitrite ions and is not affected significantly by the nature of the copper salt or other components present. Optimum fixation is obtained with a molar ratio of copper to nitrite ion of between 1:4 and 1:5.
C Waldie, J A Cornfield

The examination of preservative-treated radiata pine using electron spin resonance spectroscopy
1987 - IRG/WP 3423
Electron spin resonance spectroscopy (ESR) may be used to characterise the molecular environment of chemical species containing unpaired electrons. These species include free radicals, bi-radicals, point defects in solids, localised crystal imperfections and many transition metal ions. ESR has previously been applied to the examination of wood weathering or wood pyrolysis and now FRI and Massey University are collaborating on the use of ESR to characterise CCA-treated radiata pine. Samples examined to date have included Tanalith C-, Tanalith NCA-, and CuSO4-treated radiata pine. ESR spectra of treated wood give signals indicative of hydrated Cu2+ ions regardless of whether samples are examined in whole splinters or in ground form at room temperature or at -160°C. Comparison of the ESR spectrum of CuSO4-treated lignin with that of CuSO4-treated wood provided no evidence for copper complexation with lignin in treated wood.
D V Plackett, E W Ainscough, A M Brodie

Effects of biocides on the extracellular mucilaginous material (ECMM) produced by two wood rotting basidiomycetes
2003 - IRG/WP 03-10469
Growth and production of extracellular mucilaginous material (ECMM) by the brown-rot fungus Gloeophyllum trabeum (FPRL 108 N) and the white-rot fungus Coriolus versicolor (CTB 863 A) was assessed in liquid culture, supplemented with the biocides CuSO4 and cyproconazole. The production of biomass in G. trabeum was significantly influenced by the concentration of CuSO4 in the medium. When CuSO4 was added at 1.0 mmols l-1, biomass was reduced by approximately 35%. At this concentration, the production of ECMM, both absolute and relative to biomass, was increased. Cyproconazole had a similar effect to that observed for CuSO4, although much lower concentrations of the biocide were required to achieve a similar response. Addition of 0.1 mmols l-1 of cyproconazole to the growth medium caused a decrease of approximately 35% in the amount of biomass produced and a 200% increase in the proportional amount of ECMM produced by the fungus. A similar behaviour was also confirmed for C. versicolor . In this case, higher concentrations of CuSO4 were required in order to achieve the same levels of inhibition observed for G. trabeum. Cyproconazole-supplemented cultures also behaved similarly to G. trabeum. A concentration of cyproconazole of 0.1mmols l-1 caused a reduction of 50% in biomass and a 100% increase in the proportional amount of ECMM produced by this fungus. The presence of biocide also led to qualitative changes in the composition of ECMM. Galactose, xylose and glucose were the main components of the polysaccharide fractions of the ECMM produced by the two species growing on control media. As biocides were introduced, the proportion of galactose in the ECMM increased. This was always associated with a decrease in the proportion of glucose for G. trabeum and with a decrease in the proportion of xylose in the ECMM produced by C. versicolor. The results are discussed with regard to the possible role(s) of ECMM in the decay process and its interaction with preservative treatments.
D Vesentini, D J Dickinson, R J Murphy

Influence of fungal exposure on the redistribution of copper in treated spruce wood
2002 - IRG/WP 02-10450
The redistribution of copper in treated wood after exposure to basidiomycete decay fungi is described. The micro-distribution of copper in copper(II) sulphate or copper(II) octanoate/ethanolamine treated Norway spruce wood before and after exposure to 3 different wood decay fungi was studied using transmission electron microscopy with X-ray microanalysis. The copper content of the mycelium and the nutrient medium was also determined by atomic absorption spectroscopy. Finally, light microscopic analyses of decayed samples was performed. Both copper-tolerant (Antrodia vaillantii) and copper-sensitive fungi (Trametes versicolor and Gloeophyllum trabeum) changed the distribution of copper in the treated wood after 16 weeks of exposure. The redistribution of copper in copper sulphate treated samples exposed to tolerant A. vaillantii was characterised by the excretion of oxalic acid and formation of copper oxalate in the cell lumens, on the surface of treated wood blocks and on the fungal hyphae. In the presence of ethanolamine, the formation of copper oxalate by A. vaillantii did not occur but instead diffusion of copper into regions of lower copper concentration (centre of the blocks and nutrient medium) took place. This type of redistribution/diffusion of copper was also observed when treated wood specimens were exposed to the copper-sensitive fungi.
M Humar, F Pohleven, R J Murphy, D J Dickinson, I Moris, M Zupancic, P Kalan, M Petric

Fungal degradation of wood treated with metal-based preservatives. Part 1: Fungal tolerance
1996 - IRG/WP 96-10163
In recent years, concerns have arisen about the leaching of heavy metals from wood treated with chromated copper arsenate (CCA), particularly because of the large amount of CCA treated wood that will be discarded in the coming years. The long term objectives of this work are to determine the fate of copper, chromium and arsenic with the aging and potential decay of CCA-treated wood, and to develop strategies for recycling and remediation of disposed wood. In this study, we determined the ability of various decay fungi to decompose southern yellow pine wood treated with CCA or other metal-based preservatives. Isolates of Meruliporia incrassata and an isolate of Antrodia radiculosa caused the highest weight losses in CCA-treated southern yellow pine. One isolate of Meruliporia incrassata produced similar weight losses in CCA-treated and untreated southern pine after 10 weeks. Pine samples treated with very high levels of copper sulphate were decayed by Meruliporia incrassata, but the fungus was unable to decay wood treated with copper napthenate or copper-8-quinolinolate.
B Illman, T L Highley

Preliminary study of the fungicidal and structural variability in copper naphthenates and naphthenic acids
1996 - IRG/WP 96-30114
Copper naphthenates, an oil-borne wood preservative listed by the American Wood-Preservers' Association (AWPA), is manufactured by complexing copper(II) with naphthenic acids. Prior to AWPA listing as a wood preservative, field experiments showed that copper naphthenates generally had good stability and were active against wood-destroying organisms. Recently, however, there have been reports of some copper naphthenate-treated poles rapidly failing. One possible explanation for the varying effectiveness could be that the structure, and resulting biological activity, of the naphthenic acids used to make copper naphthenate may vary. To test this hypothesis several naphthenic acids and copper naphenates were obtained and their fungicidal activity against three wood-destroying fungi measured. In addition, the chemical structure of the naphthenic acids were examined by proton- and carbon- NMR. Different activities were observed, especially against a copper-tolerant fungus. Some apparent correlations were seen between the fungicidal activity and chemical structures for the few samples studied.
T Schultz, D D Nicholas, L L Ingram Jr, T H Fisher

Sequestration of copper ions by the extracellular mucilaginous material (ECMM) of two wood rotting basidiomycetes
2004 - IRG/WP 04-10533
The radial growth rate of colonies originating from either whole or ECMM-free inocula of Coriolus versicolor was investigated. The presence of ECMM allowed colonies to maintain higher growth rates than those form ECMM-free inocula up to 2 mM CuSO4 in the medium. The ECMM of C. versicolor and G. trabeum was able to reduce the diffusion of copper ions in solution. The ‘raw’ ECMM of both fungi had a greater ability to reduce the diffusion of copper ions than ECMM which had been subject to dialysis to remove soluble, low molecular weight components. The ‘insoluble’ fraction of ECMM for both species was more effective than the ‘soluble’ fraction at reducing the diffusion of copper ions. It is concluded that ECMM confers some protection to hyphae against the toxic effects of copper ions on growth in vivo and that this due to the binding of copper ions to both the polysaccharide and to low molecular weight components of the ECMM
D Vesentini, D J Dickinson, R J Murphy

Influence of different fixation and ageing procedures on the leaching behaviour of copper from selected wood preservatives in laboratory trials
2003 - IRG/WP 03-20264
The paper focuses on the role of different parameters, such as fixation, sample size, wood species, and leaching in internationally standardized ageing procedures for wood preservatives from Europe, Japan and the United States. The leaching protocols used were EN 84, JIS K 1571 and AWPA E11 protocols. The wood species were Scots pine, Sugi and Southern Yellow Pine respectively. Three types of commercially important copper-based wood preservatives were used as model formulations, namely copper/copper-HDO, ammoniacal copper/quat and CCA. The most important factors determining the extent of copper leaching in the different lab trials were the sample size (volume/surface ratio) and the fixation conditions prior to leaching. On the other hand, the wood species and the leaching protocol itself were found to have only minor influence on the copper leaching rate in the test methods included in this study.
J Habicht, D Häntzschel, J Wittenzellner

International collaborative laboratory comparison of two wood preservatives against subterranean termites: Third update and first report
1996 - IRG/WP 96-10174
At the 24th annual meeting of IRG in Orlando, USA, in May 1993 an international subterranean termite laboratory bioassay to compare the various preferred termite protocols used by IRG termitologists was initiated. The author was nominated to co-ordinate this comparative laboratory evaluation of two wood preservatives, copper-chrome-arsenic (CCA) and copper naphthenate (Cu-Na) against the subterranean termites used as test termites in Australia, France, Japan, Thailand, United Kingdom and the Unites States of America. Solutions of these two wood preservatives were prepared and impregnated into Pinus radiata wood blocks to obtain loading of 0.0, 0.5, 1.0, 2.0 and 4.0 kg/m³ respectively. All preservative treatments were carried out at the Division of Forestry and Forest Products in Melbourne. The treated specimens were dispatched to the participating researchers who subjected these specimens to attack by their test termite species, and have now returned the specimens to Melbourne. This paper reports the amount of wood consumed and the mean mass loss (%) on both treated and untreated wood blocks by the termites in the various laboratory bioassays.
J R J French

Types of decay observed in CCA-treated pine posts in horticultural situations in New Zealand
1984 - IRG/WP 1226
The few reported failures of 11-12-year-old horticultural posts in New Zealand in 1982 were caused by brown-rot. A subsequent survey of CCA-treated posts in all the major horticultural areas has revealed decay of many posts. A microscopic examination of these posts has shown decay by brown-rot, white-rot, soft-rot and bacteria. Several types of bacterial decay have been observed.
J A Drysdale, M E Hedley

An investigation of the effects of pre-steaming on the treatment of sawn spruce timber with Celcure A, a copper-chrome-arsenic preservative
1981 - IRG/WP 3150
Difficulties in the treatment of spruce using standard vacuum/pressure techniques with both water-borne and organic solvent preservatives are well known. We have evaluated the influence of steaming on treatability with a waterborne CCA preservative.
C R Coggins

Electrodialytic remediation of creosote and CCA treated timber wastes
2002 - IRG/WP 02-50190
There is a growing concern about the environmental issue of impregnated timber waste management, since an increase in the amount of waste of treated wood is expected over the next decades. Presently, no well-documented treatment technique is yet available for this type of waste. Alternative options concerning the disposal of treated wood are becoming more attractive to study, especially the ones that may promote its re-use. Inside this approach, the electrodialytic process (ED) seems a promising technique for removal of preservative chemicals from treated wood waste. The method uses a direct electric current and its effects in the matrix as the “cleaning agent”, combining the electrokinetic movement (mainly due to electromigration, but also electro-osmosis and electrophoresis), with the principle of electrodialysis. This work reports results from the application of the electrodialytic process to an out-of-service Portuguese creosote and CCA-treated Pinus pinaster Ait. railway sleeper and pole. The behaviour of the process is described and the main results discussed. The average removal rate, estimated in accordance with prEN 12490, for creosote from treated timber waste was around 40 %.. For CCA treated timber waste, experimental conditions that could optimise the process efficiency (e.g. current density, time) were studied. The highest removal rates obtained until now, in our studies, were 93 % of Cu, 95 % of Cr and 99 % of As for sawdust using 2.5 % oxalic acid (w/w) as the assisting agent. For CCA treated wood waste in the form of chips, the best removal rates obtained until now were 84 % of Cu, 91 % of Cr and 97 % of As.
E P Mateus, A B Ribeiro, L Ottosen

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