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The sublethal effects of 2,4-D dimethylamine on wood frog tadpoles in SaskatchewanHeggstrom, Michelle 03 September 2009
Declining amphibian populations in association with an incidence of deformities have been observed globally. These observations have alarmed the scientific community as well as the general public. Potential causes include exposure to pesticides; therefore two experiments were performed to test the sublethal effects of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) on tadpoles of the wood frog (<i>Rana sylvatica</i>). Wood frog tadpoles in the first experiment were exposed to 2,4-D amine at 0.1, 1.0 and 100 ug/L in outdoor microcosms. Morphometric measures (total length, snout-vent length (SVL) and wet weight) were taken at metamorphic climax. Deformities and circulating hormone concentrations (corticosterone - CORT) were also assessed. Results showed that though tadpoles were exposed to various concentrations of 2,4-D throughout their aquatic life, there were no treatment differences associated with any of the endpoints except for total length (p = 0.023). Total length during metamorphosis was highly variable. Although statistically significant, biological significance was questionable. The second experiment was conducted in the field using natural ponds. The experimental groups included forested ponds (removed from pesticide exposure), agricultural ponds (potentially exposed) and treated agricultural ponds (intentionally treated with 2,4-D to achieve a concentration of 10 ug/L). Relatively rapid degradation of 2,4-D occurred in all treated ponds. The mean half-life was 8.0 + 5.5 days. In spite of the degradation, 2,4-D was present in the ponds until tadpoles metamorphosed. Similar endpoints including morphometric measures, as well as deformities and plasma CORT hormone were determined. In addition, total lipid and total protein (of the carcass) were also measured. Unlike the microcosm study, statistically significant differences were observed in SVL, wet weight and total protein although the differences may have been unrelated to 2,4-D exposure. The metamorphs sampled from the forested ponds were smaller in SVL (23% shorter) and wet weight (58% lighter) (p < 0.029) relative to the other two groups. Total protein in the metamorphs from the forested ponds was 22% lower than that of the agricultural ponds (p = 0.020). Reduced hormonal response to acute stress (p = 0.001) was found in metamorphs of the forested ponds compared to those of the other two groups (66% lower response). Herbicide exposure may have induced low level stimulation of growth (a positive impact on the exposed animals), as well as a possible elevation of baseline corticosterone, in the agricultural and treated metamorphs or there may have been a negative stressor present in the forested pond environment. It is not possible to identify the specific factors that were involved. It is unclear if 2,4-D affected the growth and development of wood frog tadpoles.
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Coating Performance on Preservative Treated WoodNejad, Mojgan 31 August 2011 (has links)
Wood service life is significantly prolonged by the use of preservatives. Unfortunately, preservative treated wood is still susceptible to weathering degradation (UV and moisture) and subsequent leaching of preserving components. These negative impacts of weathering can be reduced by the application of a coating; however, the effectiveness of the coating depends on its characteristics, especially its compatibility with preservative treated wood.
In this project, the performance characteristics of semitransparent deck stains were evaluated for untreated wood samples and for samples treated with chromated copper arsenate (CCA), alkaline copper quat (ACQ) and copper azole (CA) over three years of natural and three months of accelerated weathering conditions. The parameters measured were water permeability, colour change, general appearance, checking of wood, and the coating‟s ability to reduce preservative leaching.
Coatings were characterized in terms of glass transition temperature (Tg), solid content, viscosity, density, contact angle, surface tension, and film thickness. Also penetration depth of a polyurethane (PU) coating was examined using Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS).
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All the stains evaluated effectively reduced cumulative leaching of preservative components by about 60% on average. An analysis of the preservative gradients and residual soluble components in the ACQ-samples after weathering indicated that preferential leaching of monoethanolamine (Mea) is most likely responsible for the reduced amounts of available copper in coated treated wood samples. Also, a two-week screening test was able to provide accurate predictions of the long-term leaching performance of different coatings.
There was a significant interaction effect between coatings and preservatives: solvent-based coatings showed better water repellency for CCA and untreated wood, but there was no significant difference in water repellent effectiveness between water-based and solvent-based coatings for ACQ or CA-treated wood. Overall, preservative treatments greatly enhanced coating performance. Image analysis of the samples subjected to 3 years weathering showed that coatings reduced surface checking by 30-40%.
Partial least squares regression (PLS-R) modeling was used to correlate measured coating properties with their weathering performance characteristics. The modeling results showed that coatings with low Tg and high viscosity effectively reduce the leaching of preservative components and improved water repellency and visual ratings
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Coating Performance on Preservative Treated WoodNejad, Mojgan 31 August 2011 (has links)
Wood service life is significantly prolonged by the use of preservatives. Unfortunately, preservative treated wood is still susceptible to weathering degradation (UV and moisture) and subsequent leaching of preserving components. These negative impacts of weathering can be reduced by the application of a coating; however, the effectiveness of the coating depends on its characteristics, especially its compatibility with preservative treated wood.
In this project, the performance characteristics of semitransparent deck stains were evaluated for untreated wood samples and for samples treated with chromated copper arsenate (CCA), alkaline copper quat (ACQ) and copper azole (CA) over three years of natural and three months of accelerated weathering conditions. The parameters measured were water permeability, colour change, general appearance, checking of wood, and the coating‟s ability to reduce preservative leaching.
Coatings were characterized in terms of glass transition temperature (Tg), solid content, viscosity, density, contact angle, surface tension, and film thickness. Also penetration depth of a polyurethane (PU) coating was examined using Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS).
iii
All the stains evaluated effectively reduced cumulative leaching of preservative components by about 60% on average. An analysis of the preservative gradients and residual soluble components in the ACQ-samples after weathering indicated that preferential leaching of monoethanolamine (Mea) is most likely responsible for the reduced amounts of available copper in coated treated wood samples. Also, a two-week screening test was able to provide accurate predictions of the long-term leaching performance of different coatings.
There was a significant interaction effect between coatings and preservatives: solvent-based coatings showed better water repellency for CCA and untreated wood, but there was no significant difference in water repellent effectiveness between water-based and solvent-based coatings for ACQ or CA-treated wood. Overall, preservative treatments greatly enhanced coating performance. Image analysis of the samples subjected to 3 years weathering showed that coatings reduced surface checking by 30-40%.
Partial least squares regression (PLS-R) modeling was used to correlate measured coating properties with their weathering performance characteristics. The modeling results showed that coatings with low Tg and high viscosity effectively reduce the leaching of preservative components and improved water repellency and visual ratings
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Waste from glued wood - A base for new products and/or bio-fuel?Bjurman, Therese January 2009 (has links)
The Swedwood Company is a supplier to IKEA of wood furniture. They have grown larger concurrently with IKEA and at present they have 47 production units spread over twelve countries of which most are located in Eastern Europe. One of the factories is Zbaszynek which is located in Poland. They manufacture so called board-on-frame furniture. A board-on-frame is basically made out of particle board frames which are filled with special design paper that enfolds air. The frames are then covered with their skin; thinner particle boards, so called High Density Fibre (HDF) boards, and then edge banded with plastic stripes and painted and lacquered into desired design. This production generates not only furniture, last financial year Zbaszynek generated about 61 000 tons wood waste too. It can be compared to their total production of furniture which reached 439 000 tons during the same period of time. This generation of wood waste has caused a problem for Swedwood in general. A project called IKEA Goes Renewable (IGR) has started within IKEA with the aim to reduce the electric- and heat energy consumption and increase the use of renewable energy sources. But to be able to reduce the heat energy at a board-on-frame factory, such as Zbaszynek, there has to be an economic incentive to do so. But the wood waste is contaminated in comparison with waste from pure wood (free from adhesives, plastics etc.) so purchasers have been hard to find. And since the wood waste is used to generate the heat at the factories, the economic value has become relative low. Zbaszynek earn 1.4 €/MWh for their wood waste at present (energy value of 5.1 MWh/ton), while for example recycled contaminated wood chippings (RT-chippings) are worth about 7.3 €/MWh in Sweden (energy value of 4.4-5.1 MWh/ton). RT-chippings in Sweden are even allowed to contain more contaminations to receive that price, as long as it is not pressure creosoted. 1.4 €/MWh can also be compared to the economic value of coal which is about 13.7 €/MWh, and for district heating to households in Sweden was the average price about 68 €/MWh during 2007 (Energimarknadsinspektionen, 2007).Therefore, the main task of this thesis has been to investigate if there are any possible solutions to increase the economic value of the wood waste in Zbaszynek. There are more board-on-frame factories within Swedwood with the same problem, but Zbaszynek has been the pilot factory during this research. The first thing which should be considered in Zbaszynek is to keep the amount of waste as low as possible. The main task should be to reduce the amounts of wood waste; in the end it is a furniture factory and not a waste producer, which should be concerned before taking any further action. It is assumed though that this has already been thought through in Zbaszynek and further investigation of the waste has taken place.The wood waste has been sent to the Eurofins laboratory in Sweden for an analysis and the test results were then compared to wood waste of pure wood. The comparison indicates the nitrogen content being the main difference between Zbaszynek's wood waste and pure wood. Nitrogen compounds, often referred to as NOx can cause severe damage to the environment and foremost lead to increased eutrophication (= Eutrofizacja (Polish) / Övergödning (Swedish)) when it is emitted to the air. Apart from the nitrogen contamination, other significant differences have not been found. The energy content of the wood waste has even revealed it would suit well as bio-fuel, on the condition that proper equipment to reduce the NOx emissions is present. It has been calculated that the energy content, of the generated wood waste in Zbaszynek during Financial Year 2008, reached 310 GWh. Which can be compared to the electricity consumption of 78 GWh as was bought during the same time of period. Four main possibilities have been investigated in this report and they are: - Selling the waste to cement producers as alternative fuel - Make new products and use for furniture production again - Make briquettes or pellets and sell as fuel - Start up a Combined Heat and Power plant and produce electricity All these alternatives have their advantages and disadvantages but they all seem to be realistic solutions, on a few conditions.
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The sublethal effects of 2,4-D dimethylamine on wood frog tadpoles in SaskatchewanHeggstrom, Michelle 03 September 2009 (has links)
Declining amphibian populations in association with an incidence of deformities have been observed globally. These observations have alarmed the scientific community as well as the general public. Potential causes include exposure to pesticides; therefore two experiments were performed to test the sublethal effects of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) on tadpoles of the wood frog (<i>Rana sylvatica</i>). Wood frog tadpoles in the first experiment were exposed to 2,4-D amine at 0.1, 1.0 and 100 ug/L in outdoor microcosms. Morphometric measures (total length, snout-vent length (SVL) and wet weight) were taken at metamorphic climax. Deformities and circulating hormone concentrations (corticosterone - CORT) were also assessed. Results showed that though tadpoles were exposed to various concentrations of 2,4-D throughout their aquatic life, there were no treatment differences associated with any of the endpoints except for total length (p = 0.023). Total length during metamorphosis was highly variable. Although statistically significant, biological significance was questionable. The second experiment was conducted in the field using natural ponds. The experimental groups included forested ponds (removed from pesticide exposure), agricultural ponds (potentially exposed) and treated agricultural ponds (intentionally treated with 2,4-D to achieve a concentration of 10 ug/L). Relatively rapid degradation of 2,4-D occurred in all treated ponds. The mean half-life was 8.0 + 5.5 days. In spite of the degradation, 2,4-D was present in the ponds until tadpoles metamorphosed. Similar endpoints including morphometric measures, as well as deformities and plasma CORT hormone were determined. In addition, total lipid and total protein (of the carcass) were also measured. Unlike the microcosm study, statistically significant differences were observed in SVL, wet weight and total protein although the differences may have been unrelated to 2,4-D exposure. The metamorphs sampled from the forested ponds were smaller in SVL (23% shorter) and wet weight (58% lighter) (p < 0.029) relative to the other two groups. Total protein in the metamorphs from the forested ponds was 22% lower than that of the agricultural ponds (p = 0.020). Reduced hormonal response to acute stress (p = 0.001) was found in metamorphs of the forested ponds compared to those of the other two groups (66% lower response). Herbicide exposure may have induced low level stimulation of growth (a positive impact on the exposed animals), as well as a possible elevation of baseline corticosterone, in the agricultural and treated metamorphs or there may have been a negative stressor present in the forested pond environment. It is not possible to identify the specific factors that were involved. It is unclear if 2,4-D affected the growth and development of wood frog tadpoles.
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Holzwerkstoffe in technischen Anwendungen – Anforderungen aus Sicht des Maschinenbaus / Wood as a Material in Mechanical Engineering - Concerns and RequirementsMüller, Christoph, Eichhorn, Sven, Krug, Detlef, Weber, Andreas 12 September 2012 (has links) (PDF)
Im Vortrag werden die Holzwerkstoffe charakterisiert und anderen Konstruktionswerkstoffen und technischen Verbundmaterialien gegenüber gestellt. Anhand eines Ausführungsbeispiels wird deren technologische und wirtschaftliche Leistungsfähigkeit analysiert. Darauf aufbauend werden notwendige Maßnahmen zur Verbesserung der Werkstoffe sowie zu deren Etablierung in der Technik dargestellt. Aus dem Vergleich der jeweiligen Eigenschaftsprofile werden zukünftige Nutzungsmöglichkeiten der Holzwerkstoffe in der Technik abgeleitet. Ein Ausblick zeigt den möglichen Entwicklungsspielraum für Holzwerkstoffe in technischen Anwendungen. / The properties of wood materials are compared to several engineering materials, like metal alloys, polymers and fiber reinforced plastics. The technologic and economic efficiency of plywood is illustrated by the implementation of a wooden beam. Accordingly necessary measures for the improvement of wood materials and their recognition in mechanical engineering are shown. A perspective of further fields of applications for wood materials in a technical context is given.
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The oxidation of a spruce glucomannan with lead tetraacetate.Vaughan, John M. 01 January 1963 (has links)
No description available.
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The design, preparation, characterization, and preliminary reactions of an insoluble lignin modelApfeld, Patrick B. 01 January 1986 (has links)
No description available.
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A study of lignins isolated in the presence of butanolCharbonnier, H. Y. (Harold Yale) 01 January 1941 (has links)
No description available.
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The effect of stress applied during drying on some of the properties of individual pulp fibersJentzen, Carl A. 01 January 1964 (has links)
No description available.
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