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Kilic M.,Central Anatolia Forestry Research Institute
BioResources | Year: 2011

This study was aimed at determining the effects of the force loading direction on bending strength (MOR) and modulus of elasticity (MOE) in laminated wooden materials obtained in different compositions from cut veneers of Oriental beech and Lombardy poplar with thicknesses of 4 mm and 5 mm. A total of 180 experimental specimens were prepared for determining the MOR and MOE values in parallel and perpendicular directions to the glue line. The study involved a total of 6 air-dried density layer organizations of solid Oriental beech and Lombardy popular in 4 different laminate compositions and in the same dimensions, aimed at control. Polyvinyl Acetate (PVAc) and Polyurethane (PU) were used as the adhesive type in laminations with PVAc5-PU5-PVAc4-PU4. The specimens were subjected to bending strength and modulus of elasticity experiments in parallel and perpendicular directions to the glue line in accordance with the TS EN 310 standards. As a result of the statistical analysis of the data obtained at the end of the experiments, it was determined that in the laminated materials, the force loading direction in parallel or perpendicular to the glue line affected the MOR and MOE results. The best result in the laminated materials was found to be approximately 10% higher for MOR and MOE in a parallel direction to the PU4 glue line compared to the perpendicular direction. Source


Cansaran A.,Amasya University | Dogan N.M.,Pamukkale University | Oztekin M.,Central Anatolia Forestry Research Institute | Acar G.,Pamukkale University
African Journal of Microbiology Research | Year: 2010

The antimicrobial activity was determined using the single disc diffusion method. The hexane, methanol and ethyl acetate extracts were assessed for antimicrobial activity against 13 bacteria and a yeast-like fungus, Candida albicans. While flower extracts of Centaurea cankiriense showed significant antibacterial activity against tested strains, the susceptibility of the test microorganisms was less pronounced in the cases of the stem extracts. Hexane extracts from both flower and stem did not show any antibacterial activity against gram-negative bacteria at test concentration, whereas ethyl acetate and methanol extract of C. cankiriense demonstrated the growth of both the gram-positive and the gram-negative bacteria. But, methanol extract inhibited the bacteria with the exception of two gram- negative bacteria namely Escherichia coli and Klebsiella pneumoniae. Minimum inhibition concentration (MIC) was determined on ethyl acetate extracts of flower and stem that showed high activity against the test bacteria. The MIC values for bacterial strains were in the range of 7.8 - 250 μg/ml. The results confirmed that E. coli (MIC = 250 μg/ml) and Morganelle morganii (MIC = 125 μg/ml) was the most resistant organisms to plant extracts. The flower extract of C. cankiriense was found to possess the strongest effect on Bacillus cereus with 7.8 μg/ml concentration. © 2010 Academic Journals. Source


Altun S.,Karabuk University | Burdurlu E.,Gazi University | Kilic M.,Central Anatolia Forestry Research Institute
BioResources | Year: 2010

The bending moment capacity was studied under the diagonal tensile and compression loadings of miter corner joints with dovetail fitting in frames made with medium density fiberboard (MDF). The influence of the type of adhesive in the joints with dovetail fitting on bending moment capacity under diagonal tensile and compression loading were considered, and the joints without adhesive were compared. A total of 80 each miter frame corner joint specimens with dovetail fitting were made. Polyvinyl acetate (PVAc), polyurethane (PU), and cyanoacrylate (CA) adhesives were used, and 20 specimens were prepared without adhesive (WA) with dovetail fitting. MDF was used as a frame material, as in normal practice. The specimens were subjected to diagonal tensile and compression loadings in accordance with ASTM-D 143-94. The data were analyzed statistically. The highest bending moment capacity under diagonal tensile loading (46.09 Nm) was obtained in the specimens bonded with CA adhesive and the highest bending moment capacity under diagonal compression loading (72.04 Nm) was obtained in the specimens glued with PVAc adhesive. Other than this, since there is no difference between these and the unbonded joints, the PU adhesive was not effective in increasing the bending moment capacity under diagonal tensile loading, and the PU and CA adhesives were not effective in increasing the bending moment capacity under diagonal compression loadings. Source


Ayrilmis N.,Istanbul University | Candan Z.,Istanbul University | Akbulut T.,Istanbul University | Balkiz O.D.,Central Anatolia Forestry Research Institute
Drvna Industrija | Year: 2010

The objective of this research was to investigate the effects of sanding on the surface properties of the medium density fiberboard (MDF) panels made from Rhododendron ponticum L. wood. The MDF panels were sanded with different sizes of the sand paper grit: 60-, 60+80- or 60+80+120-grit. Surface absorption and surface roughness of the MDF panels were determined based on EN 382-1 standard and ISO 4287 by using a fine stylus profilometer, respectively. Sessile water drop technique was used to determine contact angle values of the panel surface. The results indicated that sanding process improved the surface smoothness of the panels. However, the wettability and surface absorption of the panels were negatively affected by increasing grit size. The MDF surface sanded with 60-grit size had a lower contact angle, more wettable surface, compared to those that were sanded with 60+80+120-grit size. For example, the average contact angle value of the panels sanded with 60-grit sandpaper was 43.3° as compared to the panels sanded with 60+80+120-grit sand paper which was 76.1°. The rougher surface was more wettable and absorbent compared to smoother surface. Based on the findings obtained from the present study, sanding has a significant effect on the wettability, surface roughness, and surface absorption of the MDF panels, which could provide useful information on the bonding and finishing of the MDF panels. Source


Allen C.D.,U.S. Geological Survey | Macalady A.K.,University of Arizona | Chenchouni H.,University of Batna | Bachelet D.,Oregon State University | And 16 more authors.
Forest Ecology and Management | Year: 2010

Greenhouse gas emissions have significantly altered global climate, and will continue to do so in the future. Increases in the frequency, duration, and/or severity of drought and heat stress associated with climate change could fundamentally alter the composition, structure, and biogeography of forests in many regions. Of particular concern are potential increases in tree mortality associated with climate-induced physiological stress and interactions with other climate-mediated processes such as insect outbreaks and wildfire. Despite this risk, existing projections of tree mortality are based on models that lack functionally realistic mortality mechanisms, and there has been no attempt to track observations of climate-driven tree mortality globally. Here we present the first global assessment of recent tree mortality attributed to drought and heat stress. Although episodic mortality occurs in the absence of climate change, studies compiled here suggest that at least some of the world's forested ecosystems already may be responding to climate change and raise concern that forests may become increasingly vulnerable to higher background tree mortality rates and die-off in response to future warming and drought, even in environments that are not normally considered water-limited. This further suggests risks to ecosystem services, including the loss of sequestered forest carbon and associated atmospheric feedbacks. Our review also identifies key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system. Overall, our review reveals the potential for amplified tree mortality due to drought and heat in forests worldwide. Source

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