Influence of temperature on fixation of copper–ethanolamine-based wood preservatives

Market share of copper–ethanolamine-based wood preservatives is increasing in the past decade; despite of the fact that copper fixation is still not comparable to fixation of copper–chromium-based ones. One of the reasons for increased emissions originates in ethanolamine. Ethanolamine excesses depolymerizes lignin macromolecule, what consequence in higher leaching rates. In order to eliminate this negative influence of ethanolamine, Norway spruce wood blocks were impregnated with three different copper–ethanolamine solutions of three concentrations. After impregnation, specimens were dried at four different temperatures (25, 50, 75 and 103 °C) and, afterwards, leached according to the modified ENV 1250 procedure. The results showed that increased temperatures during fixation did not decrease but increased copper leaching. It is presumed that the main reason for observed fact is ethanolamine, which did not evaporate from wood. Unfortunately, increased temperatures dramatically increase lignin depolymerization, as well as copper leaching.     

Influence of wood species,treatment method and biocides concentration on leaching of copper–ethanolamine preservatives

Cu–ethanolamine-based preservatives are currently the most important alternatives for classical chromated-copper formulation. However, emissions of Cu from wood impregnated with copper–ethanolamine-based preservatives are still higher compared to emissions from wood preserved with copper–chromium based preservatives. In order to elucidate leaching of copper from specimens treated (brushed, soaked or vacuum-impregnated) with different copper–ethanolamine containing biocides of two different concentrations the following research on specimens made of Norway spruce (Picea abies), Scotch pine (Pinus sylvestris) and Beech (Fagus sylvatica) were performed. The results showed that leaching is significantly affected by the wood species used. The lowest leaching rates were determined in specimens made of spruce, while the highest ones were determined in beech wood. Concentration of active ingredient influences the Cu fixation as well. Unfortunately, ethanolamine at higher concentration causes depolymerisation of lignin macromolecules, which results in increased copper leaching.     

Evaluation of effect of leaching medium on the release of copper,chromium, and arsenic from treated wood

There is increasing public concern about environmental contamination from preservative treated wood due to release of toxic preservative components to the environment. Leaching of wood preservatives from treated wood in service can be affected by a number of factors such as wood and preservative treatment characteristics and properties of water and soil substrate in which treated wood is placed i.e. salinity, pH, and temperature. Laboratory leaching tests usually require distilled or deionized water for leaching procedure however treated wood is generally exposed to different types of water and soil conditions. This study evaluates the release of copper, chromium and arsenic elements from chromated copper arsenate (CCA)-treated wood exposed to either distilled water, tap water, sea water or humic acid. Leaching tests were conducted in laboratory conditions using wood blocks treated with CCA wood preservative at either low or high retention levels. Results showed that tap water resulted in less preservative release when compared to the other leaching media used in the study. Humic acid was the most effective medium causing more element leaching. The percentage of components leached was always higher in wood blocks treated at the high retention in comparison with the low retention level. Our results from the leaching tests can be important in developing more realistic standard leaching methods to evaluate preservative components to be released from treated wood.     

Simple modelling procedure for the indoor thermal environment of highly insulated buildings heated by wood stoves

Space heating using wood stoves is a popular solution in many European countries. The nominal power of the state-of-the-art stoves is oversized compared to the needs of highly insulated buildings, leading to a risk of overheating. A modelling procedure is here developed in order to investigate the indoor thermal environment generated by wood stoves in such buildings. This procedure is kept simple to perform all-year detailed dynamic simulations (e.g. using TRNSYS) at an acceptable computational cost. A specific experimental set-up has been developed for validation, essentially regarding the interaction between the stove and the building. The largest source of error appears to be the thermal stratification in the room where the stove is placed. The experiments prove that the model gives a fair insight into the global thermal comfort. Therefore, it is possible to investigate the conditions required for a stove to be properly integrated in a highly insulated building.     

Standardized tests fail to assess the effects of antibiotics on environmental bacteria

Pharmaceuticals are designed and used because of their specific biological effects. Over the past decade, compounds from various classes of pharmaceuticals have been detected in the environment. Concern has grown about the adverse effects pharmaceuticals in the environment might potentially have on human and ecological health. A sound risk assessment is therefore urgently needed for pharmaceuticals. Standardized tests for assessing the effects of chemicals on environmental organisms are widely used for this purpose. However it is questionable whether classical standardized tests give reliable data needed for environmental risk assessment. In this study we investigated the suitability of the respiration inhibition test OECD 209 for the assessment of the effects of antibiotics, disinfectants and cytotoxics on sewage sludge bacteria. We found that inhibition concentrations can strongly depend on the test period and the type of compound. We conclude that tests to assess the effects of pharmaceuticals on environmental organisms such as bacteria have to be evaluated before their results can be used in environmental risk assessment.     

如何欣赏木材作为建筑材料的美

借助美学的审美方法,确立了我们欣赏木材作为建筑材料之美的方法,借助人类历史,侧面体现木材运用的发展,从多角度欣赏与论证木制材料之美,方法与依据两者结合,正可构成木材作为建筑材料是美的观点。     

Comparison of three small chamber test methods for the measurement of VOC emission rates from paint

The aim of this study was to demonstrate a correlation between the measurement of emission rates of volatile organic compounds (VOCs) in three different climate chambers. In order to achieve this aim, the early state of the emission process in the three chambers was investigated and the effects of some important factors on the emission rates from paint were determined. The paper presents results of measurements in three different climate chambers. For the study, a 1-m3 chamber, a field and laboratory emission cell (FLEC), and a chamber for laboratory investigation of materials pollution and air quality (CLIMPAQ) were used. The airflow and surface area were selected so that the area-specific ventilation rates were identical in the three chambers. Temperature and relative humidity were identical during all the measurements. The paint examined was a solvent-based alkyd paint intended for indoor, which use contained between 30 and 60% of white spirit in wet condition. The paint was applied to electropolished and cleaned stainless steel plates. After application, the test material was stored for 14 days for drying in a well-ventilated conditioning room before the measurements were made. After 2 weeks storage, the most pronounced emissions were pentanal, hexanal, octanal, and decanol. The period before the emission rate stabilized differed for the three chambers studied. However, all chambers gave similar emission rates within the overall uncertainty used in these experiments.     

Poor elimination rates in waste water treatment plants lead to continuous emission of deoxynivalenol into the aquatic environment

Deoxynivalenol (DON) is one of the most prominent mycotoxins generated by fungi of the generus Fusarium on crops. Its presence in surface waters was recently demonstrated. Here, we elucidate the occurrence and behaviour of DON in three Swiss waste water treatment plants (WWTP) as a result of human consumption and excretion. DON was shown to be omnipresent in the primary effluent samples of these WWTP in concentrations from 32 to 118 ng/L. Corresponding loads were a factor of 1.3–2.3 higher than predicted based on human excretion data from the literature. DON elimination rates in WWTP ranged from 33 to 57%. These rather low percentages were confirmed with a further, more detailled study conducted at WWTP Kloten/Opfikon (average elimination rate 32%). The relative importance of WWTP as a source of DON in surface waters was compared with agricultural emissions due to runoff from Fusarium infected crops. Both sources seem to contribute equally to the total DON exposure of surface waters of a few ng/L, however, their input dynamics vary considerably in space and time.     

Leaching patterns from wood of different tree species and environmental implications related to wood storage areas

Batch tests were carried out with sawdust obtained from oak (Quercus robur), maple (Acer platanoides), pine (Pinus sylvestris), beech (Fagus sylvatica) and wood chips from oak and pine. Leaching of organic compounds expressed as dissolved organic carbon (DOC) in mg/kg of dry mass took place during the first 24 h. The following additional variables were analysed: pH, conductivity, colour, phenols, tannins and lignin, and biochemical oxygen demand (BOD₇). When leachates obtained with oak wood chips and pine wood chips were compared, no significant difference was observed. However, in batch tests with sawdust, DOC released by oak (90 000 mg/kg) was significantly higher (P = 0.0001) than DOC released by pine (30 000 mg/kg). The results suggest that particle size is not the only variable affecting the leaching of organic compounds from wood. Regarding BOD, colour [platinum‐cobalt (Pt‐Co)], phenols, tannins and lignin, the leaching patterns differed among species, and oak was the species with the highest released values.     

反观木在中国传统建筑文化中的情结

主要是针对"木"在中国传统建筑文化中的反面探讨,从五个方面分析了"木"存在的缺点,然后指出要辨证地看待"木"在中国传统建筑中的作用,以便更好地继承与发展"木"在现代建筑设计中的应用与实践。     

Finite element modelling of the pyrolysis of wet wood subjected to fire

The modelling of the pyrolysis of wet wood provides more realistic fire scenarios for structural fire design by taking into account variable thermal properties of wood which are beyond the scope of conventional structural fire design codes. The proposed numerical methodology has been written in MATLAB environment. A 2D nonlinear finite element analysis (FEA) is performed to model the pyrolysis of wet wood subjected to high temperature. The varying of thermal proprieties of wood are discussed from the point of view of changes of structure and chemical composition under fire condition. The validity of the model is established by comparing the predicted results with results from fire resistance tests presented in literature. Qualitatively, the model provides good agreement with the experimental data. It is shown that the model can handle layers of a wooden composite structure. Temperature profiles at different points in the wood sample and the two-dimensional charring depth of Laminated Veneer Lumber (LVL) panels are calculated and compared with experimental data.     

Emission rates and the personal cloud effect associated with particle release from the perihuman environment

Inhalation exposure to elevated particulate matter levels is correlated with deleterious health and well‐being outcomes. Despite growing evidence that identifies humans as sources of coarse airborne particles, the extent to which personal exposures are influenced by particle releases near occupants is unknown. In a controlled chamber, we monitored airborne total particle levels with high temporal and particle‐size resolution for a range of simulated occupant activities. We also sampled directly from the subject's breathing zone to characterize exposures. A material‐balance model showed that a sitting occupant released 8 million particles/h in the diameter range 1‐10 μm. Elevated emissions were associated with increased intensity of upper body movements and with walking. Emissions were correlated with exposure, but not linearly. The personal PM₁₀ exposure increment above the room‐average levels was 1.6‐13 μg/m³ during sitting, owing to spatial heterogeneity of particulate matter concentrations, a feature that was absent during walking. The personal cloud was more discernible among larger particles, as would be expected for shedding from skin and clothing. Manipulating papers and clothing fabric was a strong source of airborne particles. An increase in personal exposure was observed owing to particle mass exchange associated with a second room occupant.     

Thermophysical characterisation of tropical wood used as building materials: With respect to the basal density

An experimental study has been carried out to determine thermophysical properties of tropical wood. Five species, covering a wide range of densities of most of the wood used in Central Africa, has been chosen. These properties which characterise the thermally insulating materials, are related to basal density in order to help predict the thermophysical properties of any tropical wood as soon as its basal density is known. Steady-state and unsteady state methods were used to measure thermal conductivity and thermal diffusivity, respectively. Specific heat and thermal effusivity were then calculated. The influences of moisture content and the principal cutting plan on the thermophysical properties of tropical wood were examined. Higher conductivity, diffusivity and effusivity in the axial direction were observed, as well as the non-directional dependence character of the specific heat. It was also observed that thermal conductivity of tropical wood increases with infradensity both in the axial and the transverse directions. Finally, it was shown that conductivity and effusivity increase and thermal diffusivity decreases with the increase of moisture content.     

从就业看木工专业人才培养模式改革的必要性

针对木材科学与工程专业毕业生就业中存在的问题,以就业为向导,论述了木材科学与工程专业人才培养模式的弊端,指出木材科学与工程专业人才培养模式改革势在必行。     

木结构建筑在中国--从中西方木结构建筑的对比看中国木结构建筑的前景

中国有着几千年的木结构建筑历史，但在今天，木结构建筑的应用几乎成为空白。环顾四周发达国家，小到住宅，大到大型体育场馆，木结构都有广泛的应用。木材作为生态的可持续发展的建筑材料已经显示出极大的优越性。通过中西方木结构建筑的对比，探讨要不要在中国发展木结构建筑以及如何发展木结构建筑的问题。     

碳酸钾与硅溶胶复合对木材阻燃改性研究

为获得一种具有良好抑烟性能与抗流失性能的环保型木材阻燃剂,采用K2CO3与SiO2溶胶对杉木试件进行二次加压浸注处理,制得K2CO3/SiO2/木材无机质复合木材.采用锥形量热仪法(CONE)测试其阻燃性能,并测试了其抗流失性能.结果表明,杉木试件经K2CO3/SiO2复合处理后,点燃时间较未处理试件延长1倍左右,热释放速率及总量下降30％左右,抑烟性能非常显著；K2CO3/SiO2/木材的抗浸提值达到53％左右,具有较好的抗流失性能.     

Structural performance of the finger-jointed strength of some wood species with different joint configurations

This study was conducted to evaluate the effects of adhesive type, wood species, and finger joint configurations on structural performance of the finger joint. The wood species studied were oriental beech (Fagus orientalis lipsky.), oak (Quercus robur), Scots pine (Pinus sylvestris lipsky.), poplar (Populus tremula lipsk.) and Uludağ fir (Abies bormülleriana Matff.) and adhesives were poly(vinyl acetate) (PVAc), Desmodur-VTKA (D-VTKA). However, there is little information available concerning the bending strength and modulus of elasticity for finger joints in these field. In this study, it was aimed to determine the bending strength and modulus of elasticity for finger joints. For this purpose, samples were tested according to the TS EN 310 standard. It was observed that the highest bending strength and modulus of elasticity were obtained in beech control (solid wood) samples. As for the finger joints, after the control samples, the highest bending strength value (57.4 N/mm²) was obtained from Oriental beech wood samples having a 21 mm finger length and bonded with PVAc adhesive, the highest modulus of elasticity (8885.3 N/mm²) was obtained from beech wood samples having a 21 mm finger length and bonded with PVAc adhesive. As a result of the effects of finger joints on bending strength and modulus elasticity test, if the length of finger joints increases up to 21 mm, the properties of bending strength increase.     

Release of copper from sintered tungsten-bronze shot under different pH conditions and its potential toxicity to aquatic organisms

Sintered tungsten-bronze is a new substitute for lead shot, and is about to be deposited in and around the wetlands of North America. This material contains copper in the alloyed form of bronze. This in vitro study was performed according to U.S. Fish and Wildlife Service criteria to determine the dissolution rate of copper from the shot, and to assess the toxic risk that it may present to aquatic organisms. The dissolution of copper from tungsten-bronze shot, pure copper shot, and glass beads was measured in a buffered, moderately hard, synthetic water of pH 5.5, 6.6, and 7.8 over a 28-day period. The dissolution of copper from both the control copper shot and the tungsten-bronze shot was affected significantly by the pH of the water and the duration of dissolution (all p values<0.000). The rate of copper release from tungsten bronze shot was 30 to 50 times lower than that from the copper shot, depending on pH (p<0.0000). The observed expected environmental concentration of copper released from tungsten-bronze shot after 28 days was 0.02 microg/L at pH 7.8, and 0.4 microg/L at pH 5.6, using a loading and exposure scenario specific in a U.S. Fish and Wildlife Service protocol. Ratio Quotient values derived from the highest EEC observed in this study (0.4 microg/L), and the copper toxic effect levels for all aquatic species listed in the U.S. Environmental Protection Agency ambient water quality criteria database, were all far less than the 0.1 criterion value. Given the conditions stipulated by the U.S. Fish and Wildlife Service and the U.S. Environmental Protection Agency, heavy loading from discharged tungsten-bronze shot would not pose a toxic risk to potable water, or to soil. Consequently, it would appear that no toxic risks to aquatic organisms will attend the use of tungsten-bronze shot of the approved composition. Given the likelihood that sintered tungsten-bronze of the same formula will be used for fishing weights, bullets, and wheel balance weights, it is expected that the use of this new material in these applications will not be associated with toxic risks to aquatic life.     

Removal of micropollutants from urban wastewater using a UASB reactor coupled to a MBR at different organic loading rates

This study examines the removal of micropollutants (MPs) in a hybrid process that combines anaerobic and aerobic redox conditions under different Organic Loading Rates (OLRs).

A laboratory-scale pilot-plant composed of an Upflow Anaerobic Sludge Blanket reactor (UASB) combined with a membrane bioreactor (MBR) was operated. Six MPs were analyzed: the hormones estrone, 17-α-ethinyl estradiol and 17-β-estradiol, the plasticizer bisphenol A and the pharmaceuticals carbamazepine and diclofenac. In order to study its influence on removal efficiencies, the system was operated at three different OLRs: high (0.67 ± 0.15 kg COD/m³ d), medium (0.37 ± 0.06 kg COD/m³ d) and low (0.11 ± 0.02 kg COD/m³ d).

The results demonstrated the synergistic effects due to the double biological treatment, with removal rates above 90% for the hormones and the plasticizer. Pharmaceuticals were the most resistant compounds, being only partially removed in the liquid phase. Removal rates of the MPs were higher at high OLR of the influent.