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Review Citation - WoS: 53Citation - Scopus: 60Synthesis and Characterization of Hyperbranched and Air Drying Fatty Acid Based Resins(Elsevier Science Sa, 2006) Bat, E; Gündüz, G; Kisakürek, D; Akhmedov, IMIn this research four hyperbranched resins having fatty acid residues were synthesized. Dipentaerythritol, which was used as the core molecule of the resins, was twice esterified with dimethylol propionic acid. This resin was then esterified with the castor oil fatty acids. The hydroxyl group present in the ricinoleic acid which constitutes almost 87% of the castor oil fatty acids was then reacted with linseed oil fatty acids and benzoic acid. The linseed fatty acids were incorporated into the structure to esterify 0, 15, and 70% of the ricinoleic acid on mole basis. These resins were named as HBR-1, 2, and 3. A fourth resin (e.g. HBR-4) was synthesized by the incorporation of 15% linseed fatty acids + 55% benzoic acid'. The chemical characterization of the resins was achieved by FTIR spectroscopy and the thermal properties were determined by DSC. The physical and the mechanical properties of the resins were determined. The hardness value of the resins was measured as 24, 277 25, and 68 Persoz for HBR-1, 2, 3, and 4, respectively. The viscosity of the resins was measured as 17.3, 9.7, 5.8, and 17.5 Pa(.)s at a shear rate of 200 s(-1). The increase in the amount of the linseed fatty acids increased the hardness, and decreased the viscosity of the resins. All resins showed excellent adhesion, gloss, and flexibility. (c) 2006 Elsevier B.V. All rights reserved.Article Citation - WoS: 45Citation - Scopus: 48Refractive Index, Band Gap and Oscillator Parameters of Amorphous Gase Thin Films(Wiley-v C H verlag Gmbh, 2005) Qasrawi, AF; Department of Electrical & Electronics EngineeringGaSe thin films are obtained by evaporating GaSe crystals onto ultrasonically cleaned glass substrates kept at room temperature under a pressure of similar to 10(-5) Torr. The X-ray analysis revealed that these films are of amorphous nature. The reflectance and transmittance of the films are measured in the incident photon energy range of 1.1-3.0 eV. The absorption coefficient spectral analysis revealed the existence of long and wide band tails of the localized states in the low absorption region. The band tails width is calculated to be 0.42 eV. The analysis of the absorption coefficient in the high absorption region revealed an indirect forbidden band gap of 1.93 eV. The transmittance analysis in the incidence photon wavelength range of 500-1100 nm allowed the determination of refractive index as function of wave length. The refractive index-wavelength variation leads to the determination of dispersion and oscillator energies as 31.23 and 3.90 eV, respectively. The static refractive index and static dielectric constant were also calculated as a result of the later data and found to be 9.0 and 3.0, respectively.Article Citation - WoS: 4Citation - Scopus: 5Automata Networks as Preprocessing Technique of Artificial Neural Network in Estimating Primary Production and Dominating Phytoplankton Levels in a Reservoir(Elsevier, 2006) Kilic, Hurevren; Soyupak, Selcuk; Gurbuz, Hasan; Kivrak, ErsinArtificial Neural Networks (ANN) is computational architectures that can be used for estimating primary production levels and dominating phytoplankton species in reservoirs. Automata Networks (AN) were applied as a pre-processing method with subsequent ANN model development for Demirdoven Dam Reservoir. The primary purpose of using preprocessing technique was to distinguish the suitable and appropriate constituents of the input parameters' matrix, to eliminate redundancy, to enhance prediction power and calculation efficiency. The data were collected monthly over two years. The applications have yielded following results: The correlation coefficients (r values) between predicted and observed counts were as high as 0.83, 0.87, 0.83 and 0.88 for Cyclotella ocellata, Sphaerocystis schroeteri, Staurastrum longiradiatum counts, and Chlorophyll-a (Chl-a) concentrations respectively with AN. The performance of AN based pre-processing technique was compared with the performance of a well-known pre-processing technique, namely Principle Component Analysis(PCA), experimentally. r values between the predicted and observed C. ocellata, S. schroeteri and S. longiradiatum counts, and (Chl-a) were as high as 0.80, 0.86, 0.81 and 0.86 respectively with PCA. (c) 2006 Elsevier B.V. All rights reserved.Conference Object Citation - WoS: 1Changing Our Educational Institutions: Transition From Traditional To E-Learning Programs(Ieee, 2004) Yazici, A; Karakaya, Z; Dalgarno, B; Altas, IIn this. paper we examine basic elements of e-Learning, the features of the e-Learning model under implementation at Atilim University and the expected impact of the model on the organization of the institution. The paper also draws on examples at other institutions in discussing the issues that. form the dynamics of organizational change within Universities in the 21(st) century.Article Citation - WoS: 5Citation - Scopus: 6Material Flow Control in High Pressure Sheet Metal Forming of Large Area Parts With Complex Geometry Details(verlag Stahleisen Mbh, 2005) Trompeter, M; Önder, E; Homberg, W; Tekkaya, E; Kleiner, MWorking media based forming processes show advantages compared to the conventional deep drawing in the range of sheet metal parts with complex geometry details. By High Pressure Sheet Metal Forming (HBU), complex parts can be formed with reduced tool costs, fewer process steps, and improved part properties, particularly by the use of high strength steels. In order to use these advantages to full capacity, the material flow into the area of the geometry details needs to be optimised. The key element for the material flow control is a multi-point blank holder. In combination with flange draw-in sensors, a closed loop flange draw-in control can be built up which guarantees a reproducible material flow and, consequently, defined part properties. Furthermore, a favourable pre-distribution of sheet metal material can be reached which leads to a widening of the process limits. Considering a large area sheet metal part with a complex door handle element as example, strategies for the material flow control will be discussed in this paper. The conclusions are based on FE-simulations as well as experimental findings.Article Citation - WoS: 5Citation - Scopus: 7Comparison of Nat1, Nat2 & Gstt2-2 Activities in Normal and Neoplastic Human Breast Tissues(Aepress Sro, 2006) Geylan-SU, YS; Isgör, B; Coban, T; Kapucuoglu, N; Aydintug, S; Iscan, M; Güray, T; Chemical EngineeringIn this study, arylamine N-acetyltransferases, NATs (E.C.2.3.1.5) and glutathione-S-transferase-T2-2, GSTT2-2 (E.C.2.5.1.18) enzyme activities in the breast tumor and surrounding tumor-free tissues of 22 female breast cancer patients with infiltrating ductal carcinoma were measured. The possible impacts of grade of malignancy, chemotherapy treatment, estrogen receptor status and menopausal status on all enzyme activities were evaluated. The results showed that, both NAT2 and GSTT2-2 display significant differences between tumor and tumor-free breast tissues, while no difference was observed in NAT1. Grade of malignancy seems to be positively associated with NAT1 and negatively associated with GSTT2-2. Though, both NAT2 and GSTT2-2 have increased mean tumor activities, the grade of malignancy, chemotherapy status, menopausal status or estrogen receptor status are not correlated statistically.Article Citation - WoS: 5Citation - Scopus: 5Electrochemical Polymerization of Para-Substituted Haloanilines(Taylor & Francis inc, 2006) Cihaner, A; Önal, AMPolyhaloanilines: poly(4-fluoroaniline) (P4FAN), poly(4-chloroaniline) (P4CAN), and poly(4-bromoaniline) (P4BAN), are synthesized from para-substituted haloaniline monomers; 4-fluoroaniline (4FAN), 4-chloroaniline (4CAN), and 4-bromoaniline (4BAN), respectively, via constant potential electrolysis (CPE) in acetonitrile-water mixture (1:1 v/v) with NaClO4 as supporting electrolyte. Prior to CPE, electrochemical behavior of the monomers were investigated in organic medium utilizing cyclic voltammetry (CV). The course of CPE was monitored using in-situ UV-VIS spectroscopic technique. Characterization of polymer products have been carried out using FT-IR and NMR spectroscopic techniques and thermal behaviors were studied using differential scanning calorimeter (DSC). Polyhaloanilines synthesized by electrochemical oxidation were doped using iodine and the change in the paramagnetic behavior was monitored by ESR, UV-VIS, and FT-IR.Article Citation - WoS: 7Citation - Scopus: 9Electrochemical Copolymerization of 2-Substituted Thiophene Derivative Linked by Polyether Bridge With Thiophene(Elsevier Science Sa, 2005) Cihaner, A; Önal, AMNew conducting copolymers have been synthesized via electrochemical oxidation of thiophene (Th) in the presence of monomer bis(2-thienyl)ethyl (1). Cyclic voltammetry (CV) studies showed that the presence of monomer I in the electrolytic solution greatly changes the CV behaviour of the formation of the polythiophene films. It is found that the increasing ratio of I was found to decrease electroactivity of copoly(I-Th). Electrochemical synthesis of copolymer films was achieved via constant potential electrolysis (CPE) in an electrolytic solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF(6)) dissolved in CH3CN. Spectroelectrochemical (SPEL) properties of the films were investigated using UV-vis spectroscopic technique. (C) 2005 Elsevier B.V. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 4Some results related to the Laplacian on vector fields(Kossuth Lajos Tudomanyegyetem, 2006) Erkekoglu, Fazilet; Kupeli, Demir N.; Uebnal, BuelentA characterization of Euclidean spheres out of connected, compact, Einstein Riemannian manifolds of constant scalar curvature is made by a characterization of a vector field with an eigenvalue equation for the Laplacian on vector fields.Article Citation - WoS: 3Citation - Scopus: 3Modeling Chlorine Decay in Drinking Water Distribution Network: Case Study of Antalya, Turkey(Parlar Scientific Publications (p S P), 2005) Tiryakioglu, O; Muhammetoglu, A; Muhammetoglu, H; Soyupak, SThe well known hydraulic and water quality network simulation model, EPANET, is applied to the drinking water distribution network of Baris District in Antalya City, Turkey. Nine measurement and sampling stations were chosen to represent the study area. The water pressure at the pumping station was recorded during the field measurements while two different sets of water samples were analyzed in the field for chlorine residual at all the stations. Additional water samples were collected at some stations and analyzed for many physical, chemical and biological water quality parameters. Moreover, the bottle chlorine bulk decay coefficient was determined in the lab as 4.3434 day(-1). The two different field measurement sets are used to calibrate and verify the model. The calibration process resulted in a wall reaction coefficient equal to 0.025 m day(-1). In addition to predicting the chlorine residual levels along the network, the model also predicts many hydraulic characteristics such as pressure, velocity and flow rates in the network.
