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Öğe Asymmetric organocatalytic efficiency of synthesized chiral β-amino alcohols in ring-opening of glycidol with phenols(Springer Nature, 2012-04-11) Aral, Tarık; Karakaplan, Mehmet; Hoşgören, HalilA series of novel chiral β-amino alcohols 3-5 and 7-10 were synthesized by regioselective ring opening of epoxides and chiral amines with a straightforward method in high yields (up to 99 %). Kinetic resolution of racemic glycidol with phenols was achieved by using chiral amino alcohols as organocatalysts. Amino alcohols 5, 8 and 10 exhibited the highest enantioselectivities with p-cresol, phenol, and p-methoxyphenol by 63, 65, 58 % ee, respectively. The moderate enantioselectivities were observed with catalyst 9b towards all the nucleophiles (34-48 % ee). The ee values of the desired 3-aryloxy-1, 2-diols were determined by HPLC. This study presents an attractive tool for the synthesis of β-blockers and structurally complex molecules.Öğe Karyotypes of Nannospalax (Palmer 1903) populations (Rodentia: Spalacidae) from centraleastern Anatolia, Turkey(Publishing on Hystrix, 2010) Coşkun, Yüksel; Ulutürk, Servet; Kaya, AlaettinSono stati analizzati i cariotipi di 20 (11 maschi e 9 femmine) Nannospalax catturati, nel periodo 2006-2009, in 11 località dell’Anatolia centro-orientale (Turchia). Sono state individuate sei diverse forme cromosomiche (2n=49; 2n=50; 2n=52; 2n=54; 2n=60a e 2n=60b), corrispondenti a N. nehringi (N = 3), N. ehrenbergi, N. munzuri e N. tuncelicus. Nella provincia di Malatya è stata confermata la presenza di due popolazioni (2n=60a e 2n=60b), separate dal fiume Thoma. La forma 2n = 49, rinvenuta presso Pülümür, potrebbe essere un nuovo taxon.Öğe Strength and failure analysis of inverse Z joints bonded with Vinylester Atlac 580 and Flexo Tix adhesives(Springer, 2012-11) Adin, Hamit; Turgut, AydınIn this study, the tensile strength and failure loads of the inverse Z joints were analyzed both experimentally and numerically by using two adhesives with different properties under a tensile load. Vinylester Atlac 580 and Flexo Tix were used as adhesives and the joints were prepared with two different composite materials. Initially, the mechanical properties of the adhesives were specified using bulk specimens. Then, the stress analyses were performed using three-dimensional finite element method (3-D FEM) via Ansys (V.10.0.1). The experimental results were compared with the numerical results and they were found quite reasonable. According to the test results, it can be seen that when the adherend thickness is increased, the stress increases as well. The most appropriate value of the adherend thickness is identified as t = 5 mm. Furthermore, it was observed that the lowest failure load was obtained at t = 3 mm the thickness for each specimen.Öğe Callus induction and plant regeneration from different explants of actinidia deliciosa(Springer Nature, 2008-10-31) Akbaş, Filiz; Işıkalan, Çiğdem; Namlı, SüreyyaIn this study, an efficient procedure was developed for callus induction and regeneration of kiwifruit (Actinidia deliciosa) using different organs of shoots developed under in vitro conditions. Effects of explants source and media (M1, 1.0 mg l-1 BA + 2.0 mg l-1 2,4-D-M 2, 1.0 mg l-1 NAA + 2.0 mg l-1 2,4-D) on initiation of callus were examined in order to obtain callus for organogenesis. The best callus for plant regeneration was obtained from leaf explants on Murashige and Skoog's medium (MS) supplemented with M2. Formation of callus from leaf of kiwifruit (A. deliciosa) was cultured in MS medium containing different concentration of N6-benzylaminopurin (BA; 0.0, 1.0, 2.0, 4.0, 6.0, 8.0 mg l-1) for callus proliferation and plant regeneration. Although the first shoot formation was appeared in medium containing 6.0 and 8.0 mg l-1 BA, the best shoots formation was obtained in medium with 4.0 mg l-1 BA.Öğe Exhaust emissions of a CI engine operated with biodiesel from rapeseed oil(Taylor & Francis, 2011-01-16) Aydın, Hüseyin; İlkılıç, CumaliIn this study, biodiesel was produced from rapeseed oil and was used in a single cylinder, naturally aspirated and direct-injected diesel engine as pure biodiesel (B100) and as a blend with standard diesel fuel by 20% biodiesel to 80% diesel fuel (B20). The diesel engine emissions and some performance parameters were investigated at fully loaded engine conditions. The effects of pure biodiesel and its blend with diesel fuel on emissions of carbon monoxide (CO), nitrogen oxides (NOx), carbon dioxide (CO2), and sulfur dioxide (SO2) were clarified. Results showed that biodiesel fuel is environmentally friendly since it reduced the emissions of CO, SO 2, and CO2 of engines at all speeds. Results also indicated that the pure biodiesel gave about 12% lower power and 20 to 25% higher fuel consumption as compared to diesel. However, the results were almost the same or slightly different from a blend of biodiesel-diesel and petroleum diesel fuel.Öğe Current density-voltage analyses and interface characterization in Ag/DNA/p-InP structures(American Institute of Physics, 2012-02-15) Güllü, Ömer; Pakma, Osman; Türüt, AbdülmecitThe current density-voltage (J-V) characteristics of Ag/DNA/p-InP metal-insulator-semiconductor (MIS) structures have been investigated in room temperature. We have observed that the Ag/DNA/p-InP structure shows an excellent rectifying behavior and that this structure increases the barrier height (φ b0). The main electrical parameters of these structures, such as ideality factor (n), barrier height, and average series resistance values were found to be 1.087, 0.726 eV, and 66.92Ω. This value of n was attributed to the presence of an interfacial insulator layer at the Ag/p-InP interface and the density of interface states (N ss) localized at the InP/DNA interface. The values of N ss localized at the InP/DNA interface were found at 0.675-E v in the 1.38 × 10 12 eV -1 cm -2.Öğe Assessment of natural radiation exposure levels and mass attenuation coefficients of lime and gypsum samples used in Turkey(Springer Nature, 2009-11-17) Damla, Nevzat; Çevik, Uğur; Kobya, Ali İhsan; Çelik, Ahmet; Çelik, NecatiThe activity concentrations of 226Ra, 232Th, and 40K in lime and gypsum samples used as building materials in Turkey were measured using gamma spectrometry. The mean activity concentrations of 226Ra, 232Th, and 40K were found to be 38 ± 16, 20 ± 9, and 156 ± 54 Bq kg − 1 for lime and found to be 17 ± 6, 13 ± 5, and 429 ± 24 Bq kg − 1 for gypsum, respectively. The radiological hazards due to the natural radioactivity in the samples were inferred from calculations of radium equivalent activities (Raeq), indoor absorbed dose rate in the air, the annual effective dose, and gamma and alpha indices. These radiological parameters were evaluated and compared with the internationally recommended limits. The experimental mass attenuation coefficients (μ/ρ) of the samples were determined in the energy range 81–1,332 keV. The experimental mass attenuation coefficients were compared with theoretical values obtained using XCOM. It is found that the calculated values and the experimental results are in good agreement.Öğe The harmful effects of diesel engine exhaust emissions(Taylor & Francis, 2012-03-16) İlkılıç, Cumali; Aydın, HüseyinWith the increase in the number of engine vehicles, air pollution is also increasing quickly; and with the increase in air pollution, all living conditions are affected in a negative way. Diesel engines also cause air pollution, which adversely affects human health and is becoming a permanent problem. A single-cylinder diesel engine was used in this work; the exhaust gas emissions, in different speed ranges, were investigated. These emissions are carbon monoxide emissions (CO), nitrogen oxides (NO x), oxygen (O 2), and carbon dioxide (CO 2). The amount of the changes in emissions was evaluated in terms of air pollution with graphics.Öğe Current mechanism in HfO 2-gated metal-oxide-semiconductor devices(Hindawi, 2012-06-19) Pakma, OsmanThe present study aimed to examine the current density-voltage (J-V) characteristics of Al/HfO2/p-Si (MOS) structure at temperatures ranging between 100 and 320 K and to determine the structure’s current transport mechanism. The HfO2 film was coated on a single side of the p-Si (111) crystal using the spin coating method. The J-V measurements of the obtained structure at the temperatures between 100 and 320 K revealed that the current transport mechanism in the structure was compatible with the Schottky emission theory. The Schottky emission theory was also used to calculate the structure’s Schottky barrier heights (φB), dielectric constants (εr) and refractive index values of the thin films at each temperature value. The dielectric constant and refractive index values were observed to decrease at decreasing temperatures. The capacitance-voltage (C-V) and conductancevoltage (G/ω-V) characteristics of Al/HfO2/p-Si (MOS) structure was measured in the temperature range of 100–320 K. The values of measured C and G/ω decrease in accumulation and depletion regions with decreasing temperature due to localized Nss at Si/HfO2 interface.Öğe The effects of width on the strength of adhesively bonded Z joints subjected to tensile loads(Taylor & Francis, 2012-11-15) Adin, HamitIn this study, the effect of the adherend width on the tensile strength and the failure load of Z joints was analyzed both experimentally and numerically using two adhesives with different properties. Atlac™ 580 and Flexsotix™ were used as adhesives, and adherends were prepared with two different composite materials. To identify the mechanical properties of the adhesives, the bulk specimen method was used. Then, the Z joints were prepared using the aforementioned adhesives. The Z joints were subjected to tensile loads in the experiments. The stress analyses were performed using a three-dimensional finite element method (3D FEM). The 3D FEM analyses were performed with ANSYS (10.0). The 3D FEM analyses were performed to investigate the stress distributions in the adhesive layers in the Z joints. The numerical results compared favorably with the experimental results, and were found to be quite reasonable. The results showed that the joint strength increased when the specimen width (b) was increased. To maximize the performance of the joint for either adhesive, b=15mm was found to be the most suitable value for the width.
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