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.     

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.     

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%.     

Decay resistance of wood treated with boric acid and tall oil derivates

In this study, the effect of two boric acid concentrations (1% and 2%) and four derivates of tall oil with varying chemical composition were tested separately and in combination. The tall oil derivates were chosen in a way that they consist of different amounts of free fatty, resin acids and neutral compounds. Decay tests using two brown rot fungi (Postia placenta and Coniophora puteana) were performed on both unleached and leached test samples. Boric acid showed a low weight loss in test samples when exposed to fungal decay before leaching, but no effect after leaching. The tall oil derivates gave better efficacy against decay fungi compared to control, but are not within the range of the efficacy needed for a wood preservative. Double impregnation with boric acid and tall oil derivates gave synergistic effects for several of the double treatments both in unleached and leached samples. In the unleached samples the double treatment gave a better efficacy against decay fungi than tall oil alone. In leached samples a better efficacy against brown rot fungi were achieved than in samples with boron alone and a nearly similar or better efficacy than for tall oil alone. Boric acid at 2% concentration combined with the tall oil derivate consisting of 90% free resin acids (TO-III) showed the best performance against the two decay fungi with a weight loss less than 3% after a modified pure culture test.     

Effects of boron derivatives on extracellular matrix formation

Boric acid solution (3%) dramatically improves wound healing through action on the extracellular matrix, a finding that has been obtained in vitro. Consequently, investigations are presently underway to produce boronated compounds having a therapeutical effectiveness similar to that of boric acid. On the basis of experimental results obtained with boric acid, we examined the effects of boron derivatives on extracellular matrix formation and degradation and analyzed their potential toxicity by using two biological models (chick embryo cartilage and human fibroblasts). The four boron derivatives tested in this study (triethanolamine borate; N-diethyl-phosphoramidate-propylboronique acid; 2,2 dimethylhexyl-1,3-propanediol-aminopropylboronate and 1,2 propanediol-aminopropylboronate) mimicked the effects of boric acid. They induced a decrease of intracellular concentrations in extracellular matrix macromolecules (proteoglycans, proteins)-associated with an increase of their release in culture medium and stimulated the activity of intra- and extracellular proteases. Similarly to boric acid, these actions occurred after exposure of the cells to concentrations of all boron derivatives without apparent toxic effects. The compounds were found to be more toxic than boric acid itself when concentrations were calculated according to their molecular weight. Nevertheless, these in vitro preliminary results demonstrate effects of boron derivatives that may be of therapeutic benefit in wound repair.     

Determination of the concentration of complex boronated compounds in biological tissues by inductively coupled plasma atomic emission spectrometry

The application of inductively coupled plasma atomic emission spectrometry (ICP-AES) to the determination of the concentration of complex boron-containing compounds in biological tissue samples is described. Tissue digestion is achieved with perchloric acid and hydrogen peroxide in 1 hr at 75 degrees C. The ICP-AES method gave a linear response for elemental boron concentration in the range 0.05 to 100 ppm and does not require the reduction of the boron to a simple species, such as boric acid. Complete recovery of boron in complex boron cluster compounds was obtained. The procedure has been applied to the determination of the boron content in compounds synthesised for neutron capture therapy and is suitable for use in biodistribution studies of such compounds.     

巨尾桉在岩溶石山生境中的适应性研究（Ⅰ）：春季光合生理生态学特性

以岩溶石山生境的3年生巨尾桉人工林为研究对象,采用LI-6400型便携式光合仪测定巨尾桉在春季的叶片净光合速率(Pn)及其他生理生态因子日变化,同时测定巨尾桉光合-光响应曲线,并通过相关分析和通径分析探讨净光合速率与其他生理生态因子的关系。结果表明:巨尾桉光合-光响应曲线符合Walker的非直线双曲线模型。巨尾桉的光饱和点为1 340μmol.m-2.s-1,光补偿点为14.68μmol.m-2.s-1,表观量子效率(AQY)为0.06mol.mol-1,具有阳生植物的特点。净光合速率日变化呈现"单峰型"的特点。蒸腾速率(Tr)、气孔导度(Gs)和大气CO2浓度(Ca)是影响巨尾桉叶片净光合速率日变化的重要因子。巨尾桉有较高的水分利用效率,说明巨尾桉具有适应岩溶石山干旱的特征或避旱策略。     

Toxicity and repellency of borate-sucrose water baits to Argentine ants (Hymenoptera: Formicidae)

The oral toxicity of boron compounds to the Argentine ant, Linepithema humile (Mayr), was evaluated in laboratory tests. The ants were provided 25% sucrose water containing 0.5 and 1% boric acid, disodium octaborate tetrahydrate, and borax. Lethal times of these solutions were a function of the concentration of boron. In field tests, the ants showed no discrimination between disodium octaborate tetrahydrate and boric acid. There was a significant reduction in consumption of sucrose water with > 1% boric acid.     

The effects of excess boron with niacin on Daucus carota L. (carrot) root callus

Niacin (Nicotinic acid, B3 vitamin) may be involved in reduction of toxic effects of boron by regulating growth metabolism. This study was designed to examine whether external niacin treatment would improve the boron mobility in carrot callus cells or not. The results showed that excess boron caused tracheary inversions in meristematic root tissue, and also a shortage was seen in tracheary lengths with boric acid treatment. Boron excess induced the plant tolerance to water stress inverting the tracheary cells. This shortage converted nearly to normal size with niacin and boron treatment together. The results showed that boron mobility induced by niacin could reduce significantly the fresh and dry weight of carrot root cells, protein and ABA content was reduced also, in contrary, external boron and boron with niacin treatment considerable increased the two factors after one month stress. Fresh weight reduction and ABA content reduction indicated that niacin treatment caused water stress on the root cells of carrot, but boron treatment and boron with niacin treatment increased drought tolerance in carrot cells by increasing the both factors. In addition, turning the conversion of the length of the trachearies to their normal size proved that niacin treatment ended the polarizing effects of boron on cell walls.     

Functional copper requirement for catechol oxidase activity in plantation Eucalyptus species

Copper (Cu) deficiency in eucalypts is associated with tree deformation and reduced wood production from plantations. Presently, diagnosis of the early stages of Cu deficiency is unreliable as critical tissue Cu concentrations for tree growth have not been defined. Since wood quality is usually impaired in advance of tree growth, a biochemical test for Cu deficiency was sought for three Eucalyptus species commonly used in plantation forestry (E. globulus Labill., E. grandis Hill ex Maiden and E. urophylla Blake). Foliar Cu requirements for catechol oxidase activity were determined in a glasshouse sand culture study with 10 rates of Cu supply (0, 10^-15, 10^-14, 10^-13, 10^-12, 10^-11, 10^-10, 10^-9, 10^-7 and 10^-5 M). In contrast to shoot dry weight, which only responded to Cu supply in E. urophylla, foliar Cu concentration and catechol oxidase activity, in 140-day-old seedlings, increased with the addition of Cu in all species. Stem lignification also responded to Cu supply in parallel to the activity of catechol oxidase. Functional Cu requirements of 2.4, 2.1 and 2.6 mg kg^-1 dry weight for catechol oxidase activity in E. globulus, E. grandis and E. urophylla, respectively, were derived from statistical models fitted to the relationship between catechol oxidase activity and Cu concentrations in recently matured leaves.     

Measurement of borate in occupational environments

The hydration stability for inhalable borate particles has been characterized as a function of temperature and relative humidity when collected by a field personnel monitor. The rate of hydration was measured for boric acid (B[OH]3); Neobor borax 5 mol (Na2O x 2B2O3 x 5H2O); borax 10 mol (Na2O x 2B2O3 x 10H2O); anhydrous boric acid (B2O3); and anhydrous borax (Na2O x 2B2O3). The particle size is large in bulk commercial products, such that they can be handled and stored without problems. However, inhalable dust particles, in the range of 20 microm (MMD), undergo hydration/dehydration rapidly owing to their high surface-to-volume ratio. The hydration state of a collected air sample was found to be strongly dependent on the conditions of relative humidity and temperature during its collection. As a consequence, the actual chemical species of dust being inspired cannot be identified accurately. Inhalable particles of borax 10 mol placed in a field personal monitoring cartridge and exposed to dry air at 2.0 L/min at 70 degrees F for 7 h undergo rapid dehydration, producing a sodium borate residue having significantly less than four waters of hydration. Likewise, inhalable particles of anhydrous boric acid and anhydrous borax were found to hydrate under normal atmospheric conditions. Borax 5 mol and boric acid were found to be stable to dehydration. In most cases, the specific borate species or borate compounds collected in a field monitor cannot be accurately characterized other than by their boron (B) content.     

Study on some alkoxysilanes used for hydrophobation and protection of wood against decay

Two types of silanes, namely aklylalkoxysilanes and arylalkoxysilanes, were used for wood impregnation aiming at hydrophobisation of the ligno-cellulose material. The suggested mixture of alkyltriethoxysilanes and dialkyldiethoxysilanes improved water repellence when compared to conventionally used silanes. An attempt to immobilise boric acid with the siloxane matrix was also done. Decay resistance of the treated samples was tested by soil-jar test using the brown rot fungus Postia placenta.Features of the impregnated wood such as moisture content, swelling, anti-swelling efficacy and weight percentage gain were not significantly related to the mass loss of samples caused by the fungus. Samples impregnated with EtPhSi(OEt)₂ silanes showed improved durability (3.5–11.5% mass loss). Addition of boric acid to two of the silanols showed the best result for durability of wood, i.e. the lowest mass loss of 2.3 and 1.1%. These treatments upgraded the wood to “very durable”, a significant improvement from its natural status, i.e. slightly durable. The studied alkoxysilanes have moderate ability to penetrate the wood cell wall and hence to improve its hydrophobicity. These silanes are promising although more research should be carried out on the degree of oligomer polymerisation in the wood cell wall.     

Gelling properties of water-soluble polysaccharides from proliferating marine green seaweeds (Ulva spp.)

Water-soluble polysaccharides (12·2% of the algal dry weight) were extracted from marine green seaweed (Ulva spp.) which proliferate along the Brittany shores of France. They were composed of 18·4% rhamnose, 4·4% glucose, 1·9% xylose, 0·9% mannose, 0·9% galactose, 15·2% uronic acid, 15·8% sulphate and 23·7% ash based on the extract dry weight. These polysaccharides, formed a weak gel (about 3 Pa) at a concentration of 1·6% (w/v) in deionized water. The elastic modulus increased to about 160 Pa when boric acid (15–33 m ) was added and reached 250 Pa when both boric acid (7 m ) and calcium chloride (7 m ) were present. Adjusting the pH to 7·5 or higher by sodium tetraborate, phosphate or Tris-HCl buffers was detrimental to the gel. These results demonstrate that the poorly exploited biomass of Ulva spp. is a source of gelling polysaccharides of potential economical value. Mechanisms for gel formation which unusually involve both boron and calcium ions are proposed and will be studied further.     

Dietary boron supplementation enhanced the action of estrogen, but not that of parathyroid hormone, to improve trabecular bone quality in ovariectomized rats

This study investigated whether boron would enhance the ability of 17beta-estradiol (E2) or parathyroid hormone (PTH) to improve bone quality in ovariectomized OVX rats. Adult OVX rats were treated for 5 wk with vehicle, boron (5 ppm as boric acid), E2 (30 microg/kg/d, sc), PTH (60 microg/kg/d, sc), or a combination of boron and E2 or PTH, respectively. The E2 treatment corrected many adverse effects of OVX on bone quality, increased bone Ca, P, and Mg contents, and decreased trabecular plate separation. Dietary boron supplementation had no effects on these bone parameters in OVX rats. When OVX rats were treated with boron and E2 together, trabecular bone volume (Tb.BS/TV) and plate density were increased significantly more than that caused by E2 alone. The boron and E2 combination also increased trabecular bone surface (Tb.BV/TV) and decreased trabecular plate separation in OVX rats. In contrast, whereas daily PTH injection also increased bone Ca, Mg, and P contents, Tb.BV/TV, Tb.BS/TV, trabecular plate density and thickness, and decreased trabecular plate separation in OVX rats, the combination of boron and PTH had no additional improvement in bone quality over that achieved by PTH alone. In summary, this study shows for the first time that boron enhanced the action of E2, but not that of PTH, to improve trabecular bone quality in OVX rats.     

Proteomic analysis of the cambial region in juvenile Eucalyptus grandis at three ages

Recent advances in genomics and proteomics have provided an excellent opportunity to understand complex biological processes such as wood formation at the gene and protein levels. The aim of this work was to describe the proteins participating in the processes involved in juvenile wood formation by isolating proteins from the cambial region of Eucalyptus grandis, at three ages of growth (6-month-old seedlings, 3- and 6-year-old trees), and also to identify proteins differentially expressed. Using a 2-D-LC-MS/MS strategy we identified a total of 240 proteins, with 54 corresponding spots being present in at least two ages. Overall, nine proteins classified into the functional categories of metabolism, cellular processes, and macromolecular metabolism showed significant changes in expression. Proteins were classified into seven main functional categories, with metabolism representing 35.2% of the total proteins identified. The comparison of the reference maps showed not only differences in the expression pattern of individual proteins at each age, but also among isoforms. The results described in this paper provide a dynamic view of the proteins involved in the formation of juvenile wood in E. grandis.     

俄罗斯杨水培苗对硼胁迫的生长和生理响应

该研究采用水培试验,分析了俄罗斯杨(Populus russkii)对短期硼胁迫(1、5、10mmol/L硼酸)的生长和生理响应特征,探明其对硼胁迫的耐受范围,初步揭示其耐硼的生理基础。结果显示:(1)与对照相比,1mmol/L硼酸处理俄罗斯杨水培苗的生长情况更优,叶片光合色素含量和净光合速率显著上升,SOD和APX活性及抗坏血酸含量显著上调。(2)5mmol/L硼酸处理幼苗有轻微胁迫受害症状,叶片褪绿变黄,叶绿素b含量比对照显著上升,而Chla/Chlb比值显著下降,其SOD和APX活性显著上调。(3)10mmol/L硼酸处理幼苗表现出严重毒害症状,叶片发黄、茎尖和根尖生长受抑制;叶片PSⅡ原初光能转换效率(F_v/F_m)和Chla/Chlb比值比对照显著下降;其叶片MDA含量、POD活性、抗坏血酸含量以及游离脯氨酸和可溶性糖含量均比对照显著上升。研究表明,在不同浓度硼酸短期胁迫下,俄罗斯杨水培苗能通过上调抗氧化酶活性和抗氧化物质、渗透调节物质含量来有效清除体内胁迫产生的活性氧,减轻膜脂过氧化伤害,使其在低于5mmol/L硼酸胁迫环境下正常生长,表现出较强的耐硼性。     

Experimental Microbiology of Saturated Salt Solutions and Other Harsh Environments. III. Growth of Salt-Tolerant Penicillium notatum in Boron-Rich Media

A stress-tolerant strain of Penicillium notatum, isolated by passage through a nutrient solution saturated with calcium acetate, was found to have a tolerance to boron in several states of oxidation. Growth in the presence of elementary boron, saturating amounts of boric acid, and with various concentrations of sodium borohydride was observed and mycelial mats were spectrographically analyzed for boron accumulation.     

Potential Energy Wood Production with Implications to Timber Recovery and Carbon Stocks Under Varying Thinning and Climate Scenarios in Finland

An ecosystem model (Sima) was used to investigate the impact of climate and varying thinning regimes concurrently on energy wood and timber production as well as on growth and carbon stocks during 2010–2099 in southern (below 64° N) and northern (above 64° N) Finland. The analysis was carried out using sample plots from the ninth National Forest Inventory. According to the results, both energy wood and timber production increased under the changing climate, with this effect being found to be higher in northern compared to southern Finland. In relative terms, the effect of forest structure, however, was more pronounced than that of climate, especially in southern Finland. Increased basal area thinning thresholds enhanced carbon stocks compared with current thinning regime. In addition, increased thinning thresholds enhanced concurrently energy wood production (at final felling) and timber production during the period 2040–2069 and merely energy wood production (at final felling) during 2070–2099. In absolute terms, the production potential of energy wood at energy wood thinning was found to be higher in northern compared with southern Finland, but the case was opposite at final felling both in current and changing climate. It was concluded that a concurrent increase in energy wood and timber production as well as carbon stocks would be possible in Finnish forests if thinning was performed at a higher tree stocking level than in the current recommendations.