Combustion properties of Rowan wood impregnated with various chemical materials
The common use of Rowan wood (Sorbus aucuparia Lipsky) in the forest products industry of Turkey, was evaluated for some of the combustion properties after impregnation with various chemical materials. For this purpose, the wood test samples prepared from Rowan wood materials according to TS 345 were treated with Tanalith-E, Vacsol-Azure, Imersol-Aqua and Boron compounds (Borax and Boric asid) by the vacuum impregnation process in accordance with ASTM D-1413 standards and directives of the manufacturer. After impregnation, each sample was tested for observation of retention amount and combustion properties (ASTM E 160-50). It has been proven that combustion properties of the impregnated Rowan wood materials were affected by impregnated materials. As a result, combustion temperature was measured as highest in Imersol Aqua (458.686°C) and the lowest in Borax (439.023°C). The impact of impregnation material decreases after the ignition and the main impact was in flame sourced combustion. In addition, boric acid reduces the material loss in combustion, ensuring that the material is more resistant to sudden collapse and destruction. As a result, it appears that impregnation of wood material with appropriate boron treatment will further increase combustion temperatures and provide additional fire resistance and a degree of security. 
 
   
 
 Key words: Rowan wood, combustion properties, Tanalith-E, Vacsol-Azure, Imersol-Aqua, Boron compounds.
The Effects of Wood Preservatives on the Combustion Characteristics of Sessile Oak (Quercus Petreae L.)
This study carried out to determine the combustion properties of the sessile oak wood ( Quercus petraea L.) which impregnated with wood preservative and subjected to surface treatments. For this purpose, the samples, which were prepared from sessile oak wood according to ASTM–E 160-50 combustion principles,  impregnated with wolmanit-CB (WC) and tanalith-E (T) in accordance with ASTM-D 1413-76 and then synthetic (St) and Water-based (wb) varnishes were applied according to ASTM-D 3023. The combustion test was carried out in 3 stages, combustion with flame (CWF), self-combustion without flame source (CWOF) and ember combustion stage (ECP). It was aimed to determine the combustion temperature values in CWF, CWOF and ECP stage, weight loss, total combustion time and demolition time. As a result, impregnation applications have increased the total combustion time to between 15-18% and reduced the demolition period. The exact opposite results were obtained for the varnish types, the total combustion time was reduced by 19-21% and the demolition time increased by 10-22%. In CWF stage, the highest temperature was obtained in water-based varnished samples (490 °C), the lowest in non-varnished samples (458 °C); in CWOF stage the highest temperature in water-based varnished samples (572 °C), the lowest in synthetic varnished samples (544 °C); and in ECP stage the highest temperature in non-varnished samples (306.5 °C), the lowest in the samples with the synthetic varnished (262.7 °C).
Photoreflectance characterization of vanadium-doped GaAs layers grown by metalorganic vapor phase epitaxy
Abstract We characterized the vanadium-doped (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy. The conductivity of the samples is checked by the Hall effect measurements, and it is n type with electrons concentration ranging from 2×10 13 to 2×10 17  cm −3 . We used the photoreflectance technique (PR) to study the effect of vanadium doping on the optical properties of GaAs. Our experimental results show that the built-in electric field F and the broadening parameter Γ 0 increase with V-doping concentration. Furthermore, the temperature dependence of the built-in electric field and the broadening parameter of GaAs:V samples have been investigated by PR. It has been observed that these parameters increase with increasing temperature. The decrease of the built-in electric field with decreasing temperature is due to the photovoltage effect.We characterized the vanadium-doped GaAs (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy.