Amount of leachant and water absorption levels of wood treated with borates and water repellents

Wood protection efficacy of borates against biological agents, flame retardancy, and suitability to the environment is well known. Since borates can be applied to timber as water based solutions, they are preferred economically as well. Even though they are highly mobile in wood, boron compounds are widely used in timber preservation. Borates migrate in liquid and increase the hygroscopicity of wood in damp conditions. This study deals with the physical restriction of water access in wood by impregnating water repellent agents into wood to limit amount of leachant and water absorption levels of wood after boron treatment. Borates were incorporated with polyethylene glycol-400 (PEG-400) their bulking effect in wood was considered. Results indicated that the amount of leachates from wood treated with borates in PEG-400 was remarkably higher compared to those of wood treated with the aqueous solutions of borates. Water absorption (WA) levels of wood treated with aqueous solutions of borates were higher than those of their treated samples with the solutions in PEG-400. Secondary treatments of wood with the water repellent (WR) chemicals following borate impregnation reduced the leaching of chemicals from wood in water and also WA of the specimens were less than those of the wood treated with only borates from aqueous and PEG solutions. Styrene (St) was the most effective monomer among the other agents used in terms of immobility effect on borates and WA.     

Leachability,metal corrosion,and termite resistance of wood treated with copper-based preservative

Health-awareness and concern for the environment have resulted in voluntary removal of chromated copper arsenate (CCA) from wood preservatives in residential applications worldwide. Copper-based preservatives have been formulated as replacements, but these may not provide a permanent solution to all of the related problems, including copper contamination of aquatic environments and corrosion of fasteners. In this study, the copper retention (before and after the leaching process) of five softwood specimens vacuum-treated with alkaline copper quaternary (ACQ) and copper azole (CA) at three target retention levels was investigated by X-ray fluorescence studies. The metal corrosion and termite (Coptotermes formosanus) resistance of treated specimens were studied under laboratory conditions. Except for treated Japanese larch wood, the copper retention levels of the other wood specimens were able to meet the target copper retention values (use classes 2–4) in Chinese National Standard 3000. The copper leaching rates were 6.92–19.54% for ACQ-treated wood and 9.38–22.46% for CA-treated wood. The metal corrosion rates of iron nails due to corrosion tests (CNS 6717) were influenced significantly by the 1.2% ACQ and 1.2% CA treatments; whereas the metal corrosion rates of zinc-galvanized steel nails were less than 2 and could meet the tested standard. Even though the ACQ and CA treatments caused higher copper leaching rates from the treated specimens, they also increased termite mortalities and reduced the mass loss significantly after termite-resistance tests (JIS K 1571).     

Protection of Wood from Microorganisms by Laccase-Catalyzed Iodination

In the present work, Norway spruce wood (Picea abies L.) was reacted with a commercial Trametes versicolor laccase in the presence of potassium iodide salt or the phenolic compounds thymol and isoeugenol to impart an antimicrobial property to the wood surface. In order to assess the efficacy of the wood treatment, a leaching of the iodinated and polymerized wood and two biotests including bacteria, a yeast, blue stain fungi, and wood decay fungi were performed. After laccase-catalyzed oxidation of the phenols, the antimicrobial effect was significantly reduced. In contrast, the enzymatic oxidation of iodide (I⁻) to iodine (I₂) in the presence of wood led to an enhanced resistance of the wood surface against all microorganisms, even after exposure to leaching. The efficiency of the enzymatic wood iodination was comparable to that of a chemical wood preservative, VP 7/260a. The modification of the lignocellulose by the laccase-catalyzed iodination was assessed by the Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) technique. The intensities of the selected lignin-associated bands and carbohydrate reference bands were analyzed, and the results indicated a structural change in the lignin matrix. The results suggest that the laccase-catalyzed iodination of the wood surface presents an efficient and ecofriendly method for wood protection.     

Montan wax improves performance of boron-based wood preservatives

Importance of boron compounds in wood preservation is increasing due to their low environmental impact, high efficacy and the fact that many other active ingredients have been removed from the market after the introduction of the Biocidal Products Directive. The most important drawback of boron is prominent leaching in wet environment. In order to improve their fixation, and performance against wood decay fungi, boric acid was combined with montan wax emulsion. Possible synergistic effects of boric acid and montan wax were determined according to modified EN 113 procedure. Norway spruce and beech wood specimens were exposed to three white rot (Trametes versicolor, Pleurotus ostreatus and Hypoxylon fragiforme) and brown rot wood decay fungi (Gloeophyllum trabeum, Antrodia vaillantii and Serpula lacrymans) for 12 weeks. Boron leaching from vacuum/pressure treated Norway spruce wood was determined according to the continuous (EN 84 and ENV 1250-2) and non-continuous (OECD and prCEN/TS 15119-1) procedures. Boron was determined with ICP mass spectrometry in collected leachates. The results of the fungicidal tests clearly showed that montan wax emulsion and boric acid act synergistically against tested wood decay fungi. Approximately 50% lower boric acid retentions are required in combination with montan wax emulsions to achieve sufficient protection against wood rotting fungi. However, it is even more important that all leaching tests performed proved that the addition of montan wax decreased boron leaching from impregnated specimens for 20% up to 50%.     

Modification of wood with Si compounds to limit boron leaching from treated wood and to increase termite and decay resistance

In this study, we tested tetraethoxysilane and methyltriethoxysilane as modifying silicon-based compounds for their potential to limit boron leachability from modified wood and to increase biological durability of the wood against fungi and termites. Both the silane compounds were used in silane state where acidified ethanol was added and stirred at ambient temperature for 30 min. We used two different processes for preservative treatments: double treatment and single treatment. In double treatment, the specimens from sugi wood were first treated with boric acid at 1% concentration and subsequently treated with the silanes. In single treatment, boric acid was mixed with the silane compounds in the silane state yielding 1% boric acid concentration. Subsequent to the treatments, wood specimens were subjected to laboratory leaching tests, and leachates were analyzed for boron content with an inductively coupled plasma (ICP) spectrometry. ICP analyses showed that silane treatments were able to limit boron leaching from treated wood by about 40% in all cases for each silane compound. Wood specimens were then subjected to laboratory termite and decay resistance tests using the subterranean termites, Coptotermes formosanus, and the wood decaying fungi, Fomitopsis palustris and Trametes versicolor. Termite and fungal decay resistance tests revealed that resistance of modified wood with the silane and boron compounds increased when compared to untreated and boron-only treated wood specimens. More in-depth studies on the mechanisms of interactions between the silicon compounds, boron elements and wood components are in progress.     

Persistence and effectiveness of pyrethroids in plastic strips against Varroa jacobsoni (Acari: Varroidae) and mite resistance in a Mediterranean area

An apiary trial was conducted in 1997 in Sardinia, Italy, to verify the effectiveness of fluvalinate in polyvinyl chloride strips and flumethrin in polyethylene strips against Varroa jacobsoni Oudemans. Two indices to evaluate the efficacy of the treatments were adopted: percentage change in mite infestation of worker-sealed brood cells considering only treated hives and percentage change in mite mortality, and the natural variation in mite populations recorded in control hives during the trial. All acaricide treatments reduced the level of mite infestation of both sealed brood and adult bees. However, their effectiveness was slightly reduced in comparison to previous studies because of mite resistance phenomena. Portions of polyethylene strips of flumethrin from treated hives were sampled weekly to determine acaricide persistence using gas chromatography. After 4 wk, a slight reduction (approximately 9%) of the active ingredient content was observed. A laboratory bioassay also was performed to establish the resistance of adult female mites to fluvalinate. Mites were sampled from the experimental apiary and from various Sardinian apiaries which had primarily been subjected to fluvalinate applications in plastic strips or wood inserts for years. Mite resistance varied from 0 to 96%, depending on the acaricide management adopted. The lowest resistance level occurred in an apiary where pyrethroids had never been used, whereas the highest level occurred in an apiary, with intensive use of fluvalinate in wood inserts.     

Luminescent inorganic mixed borate phosphors materials for lighting

The need of new materials with desirable optical properties has become important in recent years. In particular, a need has emerged for compounds having better luminescence properties in various practical applications. The introduction of rare earth ions as activators improves the luminescence properties of the compounds considerably. Boron is one of the most abundant elements in nature. It readily combines with almost all other elements. In combination with oxygen; it forms borates comprised of various anions such as BO₃³⁻, B₂O₅⁴⁻, etc. Apart from these simple borates, several complex compositions exist involving mixed anions as well as double metal borates, due to the three-fold, or four-fold coordination of borate atoms. Borates intrinsically possesses characteristics that are advantageous for optical materials, which include a wide transparency range, large electronic band gap, good thermal and chemical stability, low preparative temperature, optical stability with good nonlinear characteristics, and an exceptionally high optical damage threshold. The unique crystal structure of borates determines their enhanced ultraviolet light transparency, good nonlinearity, and relatively high resistance against laser-induced damage. Some of these complex borates have interesting luminescence properties that are covered in this review. These include double borates containing rare earths RM₃(BO₃)₄, pentaborates LaMgB₅O₁₀, M₃R₂(BO₃)₄, where M is an alkaline earth, mixed anion borates such as aluminoborate SrAl₂B₂O₇, silicate-borates such as pekovite, SrB₂Si₂O₈, haloborates, M₂B₅O₉X, where M is an alkaline earth and X is a halogen, phosphate borates, and MBPO₅, where M is an alkaline earth. Phosphors based on these compositions find use in various applications such as fluorescence lamps, colour TVs, plasma display panels, high-intensity discharge lamps based on xenon, optically pumped solid-state lasers, eye-safe lasers, and X-ray imaging.     

Do the unique properties of nanometals affect leachability or efficacy against fungi and termites?

Nanotechnology has the potential to affect the field of wood preservation through the creation of new and unique metal biocides with improved properties. This study evaluated leachability and efficacy of southern yellow pine wood treated with copper, zinc, or boron nanoparticles against mould fungi, decay fungi, and Eastern subterranean termites. Results showed that nanocopper with and without surfactant, nanozinc, and nanozinc plus silver with surfactant resisted leaching compared with metal oxide controls. Nearly all nanoboron and boric acid was released from the treated wood specimens during leaching. Mould fungi were moderately inhibited by nanozinc oxide with surfactant, but the other nanometal preparations did not significantly inhibit mould fungi. Mass loss from Gloeophyllum trabeum was significantly inhibited by all copper preparations, while Antrodia sp. was not inhibited by nanometal treatments. Nanometals imparted high resistance in southern yellow pine to the white-rot fungus, Trametes versicolor. Unleached specimens treated with nanoboron or nanozinc plus surfactant caused 100% and 31% mortality, respectively. All specimens treated with nanozinc or nanozinc plus silver inhibited termite feeding, but the copper treatments were less effective against termites. Nanozinc possessed the most favorable properties: leach resistance, termite mortality, and inhibition of termite feeding and decay by the white-rot fungus.     

Lactic acid/wood-based composite material. Part 2: Physical and mechanical performance

The synthesis of an innovative bio-composite material based on wood and lactic acid oligomers has been reported in Part 1. As a continuation of this previous work, this paper examines the bio-composite material’s physical and mechanical performance. Properties were assessed in terms of dimensional stability, decay resistance, leaching, bending, shearing, compression and hardness testing. It has been shown that physical performance of the bio-composite was highly improved, in spite of high leaching mass loss. The mechanical structural properties were not strongly affected, except in decrease of shearing resistance due to the middle lamella degradation. An increase in hardness properties was also noticed.     

Geology and geochemistry of the Paleoproterozoic borate deposits in Liaoning-Jilin,northeastern China: evidence of metaevaporites

The borate deposits in Liaoning, Jilin province, China, are hosted in the Paleoproterozoic meta-volcanic-sedimentary sequence which comprises magnetite-microcline rocks, K- and Na-rich leptynites and leptites, magnesium marbles and amphibolites. The borates are exclusively hosted in the magnesium carbonates and Mg-silicate rocks. The association of these rocks, their sedimentary structures and unusual chemical composition suggest that their protolithes were sediments deposited in evaporite basins: red beds, zeolitized tuffs and evaporites. Therefore, the borate deposits are metamorphosed evaporites. The initial precipitates were magnesium carbonates and hydrous magnesium borates, reflecting a MgSO_4 brine stage in a playa lake environment. During the subsequent metamorphism, these borates were dehydrated to form anhydrous borates, e.g. suanite and ludwigite. These deposits are analogous to many modern evaporite sequences in rift systems. Mineralogically, these borates are comparable to the borates in the saline lakes in the Qinghai-Xizang (Tibet) plateau. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fire resistance of Douglas fir (Pseudotsuga menzieesi) treated with borates and natural extractives

The objective of this study was to determine fire resistance of Douglas fir (Pseudotsuga menzieesi (Mirb.) Franco) specimens treated with borate supplemented aqueous solutions of brutia pine bark powder, acorn powder, sumach leaf powder, and gall-nut powder. Boric acid (BA) and borax (BX) were used as borates which are the most commonly used fire retardants in wood preservation industry. Natural extractives (brutia pine bark powder, sumach leaf powder, acorn powder, and gall-nut powder) were also used which have toxic efficiency against insects and fungi due to their tannin contents. A commercial treatment compound Tanalith-CBC (copper-borate-chromate), which is an impregnation chemical, is used for comparison. The fire test method was performed in three stages: flame stage, without flame stage, and glowing stage. Results indicated that the lowest temperature for flame stage, without flame stage, and glowing stage were obtained for specimens treated with BA and BX mixture (7:3; weight:weight). The lowest mass loss was found for the specimens treated with a mixture of BA and BX. Natural extractives did not improve fire resistance of the samples. However, boric acid and borax had excellent fire retardant effectiveness over untreated and treated samples with natural extractives.     

Quaternary Ammonium Biocides: Efficacy in Application

Quaternary ammonium compounds (QACs) are among the most commonly used disinfectants. There has been concern that their widespread use will lead to the development of resistant organisms, and it has been suggested that limits should be place on their use. While increases in tolerance to QACs have been observed, there is no clear evidence to support the development of resistance to QACs. Since efflux pumps are believe to account for at least some of the increased tolerance found in bacteria, there has been concern that this will enhance the resistance of bacteria to certain antibiotics. QACs are membrane-active agents interacting with the cytoplasmic membrane of bacteria and lipids of viruses. The wide variety of chemical structures possible has seen an evolution in their effectiveness and expansion of applications over the last century, including non-lipid-containing viruses (i.e., noroviruses). Selection of formulations and methods of application have been shown to affect the efficacy of QACs. While numerous laboratory studies on the efficacy of QACs are available, relatively few studies have been conducted to assess their efficacy in practice. Better standardized tests for assessing and defining the differences between increases in tolerance versus resistance are needed. The ecological dynamics of microbial communities where QACs are a main line of defense against exposure to pathogens need to be better understood in terms of sublethal doses and antibiotic resistance.     

Effectiveness of low-temperature biochar in controlling the release and leaching of herbicides in soil

Aims

Biochars, being good sorbents of organic compounds, can reduce the mobility of pesticides in soil and subsequent pollution to groundwater, but may also impact on the efficacy of soil-applied herbicides. The aim of this study is to seek a potential solution to this problem.

Methods

We prepared a wood biochar at a relatively low heat treatment temperature (350 °C), and used it as an adsorptive carrier for incorporating the herbicides 2,4-D and acetochlor, and also as a soil amendment. Release experiment through a thin soil layer and leaching experiment through a soil column were used to evaluate the effectiveness of the biochar for controlling the release and leaching of herbicides in soil.

Results

The release experiments demonstrated that the low-temperature biochar could control the release of herbicides in soil, and the leaching experiments showed that this biochar significantly reduced the leached amount of herbicides by 1/2?~?3/4, depending on the depth (5?~?15 cm) of biochar-amended topsoil. High retention of herbicides in the biochar-amended topsoil was observed.

Conclusions

The results suggest that the low temperature biochar, if applied properly in soil, may be useful for extending the efficacy of herbicides while controlling their potential pollution.     

Chemical constituents of tropical woods and resistance to the invasive drywood termite Cryptotermes brevis

Wood-feeding, nesting and production of secondary reproductives are key determinant traits of invasive species of drywood termites, and the West Indian drywood termite Cryptotermes brevis (Walker) is one of their major examples of worldwide concern as pest species of structural lumber, furniture and other wood products. The problem and losses by this species are determined by the prevailing wood characteristics. However, despite the current widespread occurrence of this species in the tropics, except Asia, tropical wood resistance and underlying mechanisms of resistance against this termite are scarcely known. Nonetheless, wood hardness and particularly wood density were recently recognized as important underlying traits for C. brevis resistance in tropical woods, but the chemical wood constituents were not considered. Here, we assessed tropical wood resistance to the invasive termite species C. brevis and tested the relevance of their holocellulose, lignin and (total) extractive contents preventing termite infestation. Free-choice and no-choice tests were carried out in parallel with wood chemical characterization. Resistance to the West Indian termite varied with wood species in terms of both colonization and consumption, but only under free-choice testing because without choice, no significant difference was detected among wood species. Regardless, none of these traits were significantly correlated with wood resistance to C. brevis. Therefore, wood physical resistance, particularly wood density, seems the main recognized determinant of tropical wood resistance against the West Indian drywood termite. The pattern of termite movement on the surface of soft, mid and hard wood was also consistent with this conclusion.     

The utility of bulk wood density for tree-ring research

Bulk wood density measurements are recognized for their utility in ecology, industry, and biomass estimations. In tree-ring research, microdensitometric techniques are widely used, but their ability to determine the correct central tendency has been questioned. Though rarely used, it may be possible to use bulk wood density as a tool to check the accuracy of and even correct microdensitometric measurements. Since measuring bulk wood density in parallel with X-ray densitometry is quickly and easily done, we suspect that its omission is largely due to a lack of awareness of the procedure and/or its importance. In this study, we describe a simple protocol for measuring bulk wood density tailored for tree-ring researchers and demonstrate a few possible applications. To implement real-world examples of the applications, we used a sample of existing X-ray and Blue Intensity (BI) measurements from 127 living and dead Pinus sylvestris trees from northern Sweden to produce new measurements of bulk wood density.We can confirm that the central tendency in this sample material is offset using X-ray densitometry and that the diagnosis and correction of X-ray density is easily done using bulk wood density in linear transfer functions. However, this approach was not suitable for our BI measurements due to heavy discoloration. Nevertheless, we were able to use bulk wood density to diagnose and improve the use of deltaBI (latewood BI – earlywood BI) with regard to its overall trends and multi-centennial variability in a dendroclimatological application. Moreover, we experimented with percent of latewood width, scaled with bulk wood density, as a time- and cost-effective proxy for annual ring density. Although our reconstruction only explains about half of the variation in ring density, it is most likely superior to using fixed literature values of density in allometric equations aimed at biomass estimations.With this study, we hope to raise new awareness regarding the versatility and importance of bulk wood density for dendrochronology by demonstrating its simplicity, relevance, and applicability.     

Hydrogels obtained from an original catanionic system for efficient formulation of boron wood-preservatives

A new catanionic system associating amphiphilic carnosine (βAlaHisC8) and lauric acid forms supramolecular hydrogel at a very low concentration. This gel was investigated and we checked the validity of the concept of hydrogel utilization to reduce boron leachability and to develop new wood protection treatments. Impregnation with 5% aqueous borax solution (w/w) and 0.3% gelator agent (w/w) fosters improvement in the resistance of Scots pine sapwood subjected to water leaching toward the brown-rot fungus Poria placenta, while samples treated with 5% aqueous borax solution were partially degraded by the fungus. These results clearly indicate the effectiveness of hydrogel to retain boron in wood.     

Molecular genetic tools to infer the origin of forest plants and wood

Most forest tree species exhibit high levels of genetic diversity that can be used to trace the origin of living plants or their products such as timber and processed wood. Recent progress to isolate DNA not only from living tissue but also from wood and wood products offers new opportunities to test the declared origin of material such as seedlings for plantation establishment or timber. However, since most forest tree populations are weakly differentiated, the identification of genetic markers to differentiate among spatially isolated populations is often difficult and time consuming. Two important fields of “forensic” applications are described: Molecular tools are applied to test the declared origin of forest reproductive material used for plantation establishment and of internationally traded timber and wood products. These applications are illustrated taking examples from Germany, where mechanisms have been developed to improve the control of the trade with forest seeds and seedlings, and from the trade with wood of the important Southeast Asian tree family Dipterocarpaceae. Prospects and limitations of the use of molecular genetic methods to conclude on the origin of forest plants, wood, and wood products are discussed.     

Fixation,leachability, and decay resistance of wood treated with some commercial extracts and wood preservative salts

Beech (Fagus orientalis) and Scots pine (Pinus sylvestris) wood blocks were treated with some commercial extracts as well as water-based wood preservative salts at various concentrations to increase retention and fixation. The penetration, fixation, and antifungal properties of different treatment solutions were compared with statistical analysis. Retention levels of solutions were generally higher for Scots pine wood than beech wood. The highest retention levels were seen in wood treated with sumac leaf extract and oak valonia extract. Leaching tests indicated that both wood types treated with sumac extracts showed higher retention levels than wood treated with the other fruit and bark extract solutions. Adding 1% water-based wood preservative salts to valonia and sumac leaf extracts increased the retention levels. Concentrations of more than 1% did not contribute to retention either individually or with salt additions. Three percent and higher concentrations of wood-preserving salts accelerated and increased the amount of leaching. The results showed that the extract alone was resistant to leaching. Mycological tests showed that all extractives were significantly effective against wood decay.     

Performance of oak,beech and spruce beams after more than 100 years in service

The aim of this study was to investigate differences in the mechanical and fungicidal properties of three different wood species (English oak (Quercus sp.), common beech (Fagus sylvatica) and Norway spruce (Picea abies)) that had been in indoor use for several decades, compared to control specimens of freshly cut timber. The collected material was cut into smaller samples prior to further analysis. Extractive content, mechanical, fungicidal and sorption properties were determined according to standard procedures. The obtained results showed that the mechanical properties of oak wood do not deteriorate over the investigated time frame. On the other hand, the resistance of oak wood against fungi decreases over time. The reason for this is yet to be confirmed; it may be due to degradation of secondary metabolites. Similar results have been reported for spruce wood. There were no statistically significant differences in the mechanical properties of old and new spruce wood. In contrast to oak wood, there were also no significant differences in fungicidal properties, bearing in mind that spruce wood has lower durability than oak wood. Aging of beech wood resulted in a considerable decrease in the tested mechanical properties but showed no significant differences in fungicidal properties. Old beech wood specimens were moderately deteriorated by insects and fungi, which was the reason for the loss of bending and compressive strength. Our results confirm that most of the relevant properties do not deteriorate with time and that wood can be reused for a variety of other applications even after decades in service.     

Evaluation of decay and termite resistance of wood treated with copper in combination with boron and N′-N-(1, 8-naphthalyl) hydroxylamine (NHA-Na)

This study evaluated the relative ability of various combinations of copper sulfate with either boric acid or calcium-precipitating agent, N′-N-(1, 8-naphthalyl) hydroxylamine (NHA-Na), to inhibit fungal degradation and attack by Formosan subterranean termites (Coptotermes formosanus Shiraki). Wood specimens were treated with either 1%, 0.5%, or 0.1% concentrations of copper sulfate, boric acid, NHA-Na, copper sulfate + boric acid, or copper sulfate + NHA-Na mixtures. Treated specimens were subjected to laboratory decay-resistance tests by using petri dishes inoculated with the Basidiomycetes fungi Tyromyces palustris and Trametes versicolor for 12 weeks. Treated wood specimens were also subjected to termite-resistance tests under laboratory conditions. Increased efficacy of copper sulfate against the brown-rot fungus T. palustris was observed when either boric acid or NHA-Na was added. The most effective treatments against the fungi tested were NHA-Na only treatments at 1% and 0.5% concentration levels. Boric acid treatments were not able to protect wood against decay after leaching because of excessive leaching of boron. Similar results were obtained in termite-resistance tests in comparison with decay-resistance tests. These results indicate that the efficacy of the treatments in preventing fungal and termite attack is a function of the type of preservative.