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Bartn, Turkey

Bolat I.,Bartin University
European Journal of Forest Research | Year: 2014

Reducing the canopy cover (e.g., forest thinning) is one of the most commonly employed forest silvicultural treatments. Trees are partially removed from a forest in order to manage tree competition, thus favoring the remaining and often the most valuable trees. The properties of the soil are affected by forest thinning as a result of changes in key microclimatic conditions, microbial communities and biomass, root density, nutrient budgets and organic matter turnover. The aim of this study was to determine the soil microbial biomass C, N and respiration (basal respiration) in a black pine (Pinus nigra Arn. subsp. pallasiana) forest in the Mudurnu district of Bolu Province (Western Black Sea Region, Turkey). Whereas forest thinning was found to cause increases in the soil temperature, microbial biomass C and N and organic C, it was found to decrease the soil moisture, basal respiration and metabolic quotient (qCO2). As expected, soil organic C exhibited a strong impact on soil microbial biomass C, N and basal respiration. It was concluded that the influence of forest thinning on the microbial biomass and soil respiration was the combined result of changing microclimatic conditions and soil properties, such as forest litter, soil temperature, soil moisture, soil pH and soil organic matter. © 2013 Springer-Verlag Berlin Heidelberg.

Caliskan H.,Bartin University
Materials and Design | Year: 2013

Mechanical and tribological properties of hard coatings can be enhanced using boron as alloying element. Therefore, multicomponent nanostructured boron based hard coatings are deposited on cutting tools by different methods at different parameters. Different mechanical and tribological properties are obtained after deposition, and it is a difficult task to select the best coating material. In this paper, therefore, a systematic evaluation model was proposed to tackle the difficulty of the material selection with specific properties among a set of available alternatives. The alternatives consist of multicomponent nanostructured TiBN, TiCrBN, TiSiBN and TiAlSiBN coatings deposited by magnetron sputtering and ion implantation assisted magnetron sputtering at different parameters. The alternative coating materials were ranked by using three multi-criteria decision-making (MCDM) methods, i.e. EXPROM2 (preference ranking organization method for enrichment evaluation), TOPSIS (technique for order performance by similarity to ideal solution) and VIKOR (VIšekriterijumsko KOmpromisno Rangiranje), in order to determine the best coating material for cutting tools. Hardness (H), Young's modulus (E), elastic recovery, friction coefficient, critical load, H/E and H3/E2 ratios were considered as material selection criteria. In order to determine the importance weights of the evaluation criteria, a compromised weighting method, which composes of the analytic hierarchy process and Entropy methods, were used. The ranking results showed that TiBN and TiSiBN coatings deposited at given parameters are the best coatings for cutting tools. © 2013 Elsevier Ltd.

Aksakal O.,Ataturk University | Ucun H.,Bartin University
Journal of Hazardous Materials | Year: 2010

This study investigated the biosorption of Reactive Red 195 (RR 195), an azo dye, from aqueous solution by using cone biomass of Pinus sylvestris Linneo. To this end, pH, initial dye concentration, biomass dosage and contact time were studied in a batch biosorption system. Maximum pH for efficient RR 195 biosorption was found to be 1.0 and the initial RR 195 concentration increased with decreasing percentage removal. Biosorption capacity increased from 6.69mg/g at 20°C to 7.38mg/g at 50°C for 200mg/L dye concentration. Kinetics of the interactions was tested by pseudo-first-order and pseudo-second-order kinetics, the Elovich equation and intraparticle diffusion mechanism. Pseudo-second-order kinetic model provided a better correlation for the experimental data studied in comparison to the pseudo-first-order kinetic model and intraparticle diffusion mechanism. Moreover, the Elovich equation also showed a good fit to the experimental data. Freundlich and Langmuir adsorption isotherms were used for the mathematical description of the biosorption equilibrium data. The activation energy of biosorption (Ea) was found to be 8.904kJ/mol by using the Arrhenius equation. Using the thermodynamic equilibrium coefficients obtained at different temperatures, the study also evaluated the thermodynamic constants of biosorption (ΔGo, ΔHo and ΔS). The results indicate that cone biomass can be used as an effective and low-cost biosorbent to remove reactive dyes from aqueous solution. © 2010 Elsevier B.V.

In this study, the defects observed on the Chenille yarn, (a member of the class of fancy yarns), have been converted into digital signals through an experimental system composed of an optoelectronic sensor. The effect of the production properties of the yarn (material, yarn count, pile density) and the wavelength of the light transmitter (LED) on the signal-to-noise ratio (SNR) of the sensor signal have been investigated. The parameters affecting the amplitude of the noise signal and the amplitude of the defect signal have been identified using the Fresnel formulae and the formulae established in geometrical optics. Mathematical formulae presenting the dependence of the amplitude of the sensor signal on the radiant intensity emerging from the transmitter in the experimental setup (IF), the geometrical parameters of the measurement system (distance between the yarn and the light transmitter, the numerical aperture of the slot) and the production parameters for the yarn (pile yarn diameter, core yarn diameter, pile density, defect length) have been obtained. The transmission indexes for wool, polyester, viscose and acrylic Chenille yarn of the same yarn count (3 Nm) and for 4.2 Nm acrylic and 5.5 Nm polyester Chenille yarn have been determined experimentally for the peak wavelengths of 467 nm, 489 nm, 520 nm, 590 nm, 640 nm and 850 nm in the light transmitter of the optoelectronic measurement device. The dominant parameter in the determination of the SNR value of the sensor system has been concluded to be the pile density of the yarn. When yarn of the same material with increasing yarn counts via decreasing pile densities (3-4.2 Nm acrylic and 3-5.5 Nm polyester) is used, the SNR values decrease with increasing the amplitude of the transmittance voltage. SNR is determined by the optical characteristics of the yarn when they are of the same yarn count, twist level and pile density. In this study, the SNR values of the acrylic yarns have been determined to be lower than those of the polyester and viscose yarns of the same pile density and the same yarn count due to their higher transmittance properties. It has been obtained that the changes observed in the transmittance characteristics in response to varying wavelengths of the transmitter become more important in the identification of shorter length defects with high SNR. © 2011 Elsevier B.V. All rights reserved.

Pekgozlu I.,Bartin University
Journal of Luminescence | Year: 2013

M2Mg(BO3)2:Sm3+ (M:Sr and Ba) phosphors were synthesized by a solution combustion synthesis method followed by heating of the precursor combustion ash at 900 °C in air. The synthesized materials were characterized by using the powder XRD. The emission and excitation spectra of these materials were measured at room temperature with a spectrofluorometer. Both Sr2Mg(BO3)2:Sm 3+ and Ba2Mg(BO3)2:Sm3+ phosphors emit a strong in orange-red region. It was observed that the optimum concentration of Sm3+ in Sr2Mg(BO3)2 and Ba2Mg(BO3)2 are 0.01 and 0.04 mol, respectively. Finally, the relation between the photoluminescence properties of Sm3+ and host compositions was discussed in detail. © 2012 Elsevier B.V. All rights reserved.

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