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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 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 Multivariate padé approximation for solving partial differential equations (PDE)(Wiley-Blackwell, 2011-07-30) Turut, Veyis; Çelik, Ercan; Yiğider, MuhammedIn this paper, numerical solution of partial differential equations (PDEs) is considered by multivariate padé approximations. We applied these method to two examples. First, PDE has been converted to power series by two-dimensional differential transformation, Then the numerical solution of equation was put into multivariate padé series form. Thus, we obtained numerical solution of PDE.Öğe Calculating molding parameters in plastic injection molds with ANN and developing software(Taylor & Francis, 2012-02) Çelik, Yahya Hışman; Özek, CebeliIn recent years, plastic injection molds are widely used for producing products in various areas, such as aerospace, automotive, medical, electronics, and toys. The quality of these products depends on correctly chosen molding parameters. In this study, a new package program (NPP)-Software that calculates various injection molding parameters was developed to mold plastic products obtained by plastic injection molding techniques using the model of artificial neural network (ANN). The Delphi programming language was used in the develop the (NPP)-Software. The developed (NPP)-Software was trained and tested using the Levenberg–Marquardt (LM) algorithm, the ANN. One-thousand three-hunderd pieces of data were collected, out of which 250 were used to train the network. The ANN is employed to find optimum molding parameters that enable minimum defects in the injection-molded part, such as volumetric shrinkage, injection time, and cooling time. The three parameters predicted, using the (NPP)-Software, were compared using experimental results.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 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.Öğe Emissions from an engine fueled with biodiesel-kerosene blends(Taylor & Francis, 2011-01) Aydın, Hüseyin; Bayındır, Hasan; İlkılıç, CumaliBiofuels are renewable energy sources for internal combustion engines and they have low emissions. They are increasingly used as an alternative to petroleum fuels. In this work, three different fuel types, such as commercial diesel fuel (D2), 20% biodiesel and 80% diesel fuel called here as B20, and 80% biodiesel and 20% kerosene, called here as BK20, were used in a single cylinder, four stroke, direct injection compression ignition engine. Kerosene was used as an additive to approach the properties of biodiesel to D2. The effects of the blends on CO, NOx, and smoke emissions as well as on some of the performance parameter of the engine were investigated. The prepared fuel, BK20 blend, has almost the same fuel properties as conventional diesel fuel. The experimental results showed that the exhaust emissions for BK20 were fairly reduced as compared to diesel fuel as well as B20. Besides, the performance of CI engine was improved with the use of the BK20, especially in comparison to B20. Results suggest that the BK20 can be substituted to the petroleum-based diesel fuel in diesel engines.Öğe Electrochemical determination of melatonin hormone using a boron-doped diamond electrode(Elsevier, 2012-01) Levent, AbdulkadirIn this study, a boron-doped diamond electrode was used for the electroanalytical determination of melatonin in the pharmaceutical tablet and urine samples by square-wave voltammetry. Melatonin yielded a well-defined voltammetric response in Britton-Robinson buffer, pH 3.0 at + 0.88 V (vs. Ag/AgCl). Using the optimal square-wave voltammetry conditions, the oxidation peak was used to determine melatonin in the concentration range of 5.0 × 107 M to 4.0 × 106 M (r = 0.998, n = 8), a detection limit of 1.1 × 107 M (0.025 μg/mL) and relative standard deviation was 2.06% at the 2.0 × 106 M level (n = 10). Recoveries of melatonin were in the range of 97.67–105%, for both tablet and spiked human urine samples.Öğe The effects of λ and ε on engine performance and exhaust emissions using ethanol-unleaded gasoline blends in an SI engine(Taylor & Francis, 2011-01) Bayındır, Hasan; Yücesu, Hüseyin Serdar; Aydın, HüseyinIn this study, the effect of relative air-fuel ratio (λ) and compression ratio (ε) on engine performance and exhaust emissions was experimentally investigated. The experiments were performed by varying ethanol-unleaded gasoline blends as E0 (100% unleaded gasoline), E10 (10% ethanol and 90% gasoline blend), E30 (30% ethanol and 70% gasoline blend), and E85 (85% ethanol and 15% gasoline blend). In experiments, first the effects of ethanol-unleaded gasoline blends on engine performance and exhaust emissions at 0.931, 1, and 1.069 λ values were clarified. Second, tests were carried out with compression ratios of 7:1, 9:1, and 11:1. The results indicated that the relative air-fuel ratio and ethanol content play an important role in reducing CO (carbon monoxide emissions) and HC (hydrocarbon) emissions. Results also showed that the engine power was slightly decreased, especially at higher engine speeds. A probable knocking phenomenon did not occur with the increase of compression ratio because of a higher octane number of ethanol-unleaded gasoline blends.Öğe In vitro antimicrobial and antioxidant activity of ethanol extract of three hypericum and three achillea species from Turkey(Taylor & Francis, 2011-02-25) Barış Cebe, Deniz; Kızıl, Murat; Aytekin, Mehmet Çetin; Kızıl, Göksel; Yavuz, Murat; Çeken Toptancı, Bircan; Ertekin, Alaattin SelçukThe present study was conducted to determine the antimicrobial, antifungal and antioxidant activity of the ethanol extract of Hypericum scabrum L (HSm), Hypericum lysimachioides var. lysimachioides (HL), and Hypericum retusum Aucher (HR) and ethanol extracts of Achillea aleppica D.C. subsp. aleppica (AA), Achillea aleppica D.C. subsp. zederbaueri (Hayek) Hub.-Mor (AZ), and Achillea biebersteinii Afan. (AB). The antioxidant properties of extracts were evaluated using different antioxidants tests, including reducing power, free radical scavenging, deoxyribose assay, metal chelating activities and determination of total phenolic compounds. The extracts obtained from Hypericum and Achillea species showed high antioxidant properties. The protective effects of plant extracts were compared with a well known antioxidant, Butilated Hydroxytoluen (BHT) and α-tocopherol. Total antioxidant activity of ethanol extracts of plants were also tested by using ferric thiocyanate (FTC) and thiobarbituric acid (TBA) methods. Antioxidative activities of plant extracts were found to be comparable with Vitamin E. The results showed that the ethanol extracts of all tested plant exhibited different activity against tested microorganisms. Since most of the studied extracts have good antimicrobial and antioxidant activity, it might be possible to use them as natural food additives that act both as antioxidants and as spices.
