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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only The triangle intersection problem for K4 - E designs(Utilitas Mathematica Publishing Inc., 2007) Billington, Elizabeth J.; Lindner, C. C.; Department of Mathematics; Yazıcı, Emine Şule; Faculty Member; Department of Mathematics; College of Sciences; 27432An edge-disjoint decomposition of the complete graph Kn into copies of K4 - e, the simple graph with four vertices and five edges, is known to exist if and only if n ≡ 0 or 1 (mod 5) and n ≥ 6 (Bermond and Schönheim, Discrete Math. 19 (1997)). The intersection problem for K4 - e designs has also been solved (Billington, M. Gionfriddo and Lindner, J. Statist. Planning Inference 58 (1997)); this problem finds the number of common K4 - e blocks which two K4 - e designs on the same set may have. Here we answer the question: how many common triangles may two K4 - e designs on the same set have? Since it is possible for two K4 - e designs on the same set to have no common K4 - e blocks and yet some positive number of common triangles, this problem is largely independent of the earlier K4 - e intersection result.Publication Metadata only Resonant channel-dropping filter with integrated detector system based on optical fiber coupler and microsphere(IOP Publications, 2004) İşci, Şenol; Yılmaz, Yiğit; Department of Physics; Serpengüzel, Ali; Kurt, Adnan; Bilici, Temel; Faculty Member; Teaching Faculty; N/A; Department of Physics; College of Sciences; N/A; 27855; 194455; N/APublication Metadata only Z(n)-graded topological generalizations of supersymmetry and orthofermion algebra(Iop Publishing Ltd, 2003) N/A; Department of Mathematics; Mostafazadeh, Ali; Faculty Member; Department of Mathematics; College of Sciences; 4231We review various generalizations of supersymmetry and discuss their relationship. in particular, we show how supersymmetry, parasupersymmetry, fractional supersymmetry, orthosupersymmetry, and the Z(n)-graded topological symmetries are related.Publication Metadata only Structures and properties of NbOF3 and TaOF3 - with a remark to the O/F ordering in the SnF4 type structure(Wiley-V C H Verlag Gmbh, 2002) Köhler, J; Simon, A; van Wullen, L; Cordier, S; Roisnel, T; Poulain, M; Department of Chemistry; Somer, Mehmet Suat; Faculty Member; Department of Chemistry; College of Sciences; 178882Powder samples of NbOF3 und TaOF3 were prepared by heating mixtures of NbO2F and NbF5 or TaO2F and TaF5, respectively, in the corresponding stoichiometric ratio in platinum crucibles under argon atmosphere (180-220degreesC). Both oxide fluorides are coulourless with a slight greyish tinge. They are sensitive to moisture and decompose in air at room temperature within hours. Both, NbOF3 and TaOF3 crystallize as a variant of the SnF4 type structure, space group 14/mmm. The structures have been refined from X-ray powder diffraction data using the Rietveld method (a = 3.9675(1) Angstrom, c = 8.4033(1) Angstrom, R-B = 3.60%, R-p = 4.58% for NbOF3 and a = 3.9448(1) Angstrom, c = 8.4860(1) Angstrom, R-a = 2.07%, R-p = 2.44% for TaOF3). Characteristic building units are sheets of corner sharing MX6 octahedra which are stacked via van der Waals interactions to a three dimensional framework. The occupancy of the two crystallographic sites for the anions by O and F is discussed on the basis of structure refinements, bond order summations, IR and NMR data and calculations of the Madelung parts of the lattice energy.Publication Metadata only Nanoparticle silicalite-1 crystallization from clear solutions: nucleation(Elsevier Science Bv, 2009) Tokay, Begüm; Erdem-Şenatalar, Ayşe; Schueth, Ferdi; Thompson, Robert W.; Department of Chemistry; Somer, Mehmet Suat; Faculty Member; Department of Chemistry; College of Sciences; 178882Despite much effort spent by various research groups, there remain many aspects of nanoparticle silicalite-1 crystallization from clear solutions which require further investigation. In order to shed light, especially on the nucleation of silicalite-1, particle growth at 100 degrees C from several starting compositions known to yield colloidal silicalite-1, which have been studied previously by other researchers using various techniques, was followed in this study by laser light scattering using scattering angles of 90 degrees and 173 degrees, and zeta potential and pH measurements. Crystallinity was monitored by X-ray diffraction, Fourier transform infrared analysis and transmission electron microscopy. Thermogravimetric analyses and density measurements were also used to characterize the products obtained at various times during the syntheses. The results demonstrate that the distinct time of sudden jump in the effective diameter of the nanoparticles in solution, as observed more clearly by using the back-scattering device, and which marks the beginning of the constant linear growth rate of the particles, corresponds to the nucleation of the silicalite-1 crystal structure. This time was also shown to coincide with the exo-endo thermal switch time of the reaction mechanism, which has been observed previously by another research group. Nucleation was accompanied by an aggregation of a population of smaller particles, as indicated by the broadening of the particle size distribution, and the variation of the pH and zeta potential values during synthesis.Publication Metadata only Crystallization of poly(ethylene oxide) in thin films(Taylor & Francis Inc, 2003) N/A; Department of Chemistry; Department of Chemistry; Ok, Salim; Demirel, Adem Levent; Undergraduate Student; Faculty Member; Department of Chemistry; College of Sciences; College of Sciences; N/A; 6568Crystallization of poly(ethylene oxide) (PEO) in thin films was studied using hot-stage polarized optical microscopy. Isothermal linear crystal growth rates were measured for various film thicknesses at various degrees of undercooling. At a given crystallization temperature, the linear crystal growth rate decreased exponentially with decreasing film thickness below a film thickness of 80 nm. Films showed similar spherulitic morphology down to a film thickness of 30 nm. Control experiments on hydrophilic and hydrophobic surfaces showed that surface chemistry affects stability of the polymer films and causes a competition between crystallization and dewetting.Publication Metadata only Exactly solvable pairing model using an extension of the Richardson-Gaudin approach(World Scientific Publ Co Pte Ltd, 2005) Balantekin, AB; Pehlivan, Y; Department of Physics; Dereli, Tekin; Faculty Member; Department of Physics; College of Sciences; 201358We introduce a new class of exactly solvable boson pairing models using the technique of Richardson and Gaudin. Analytical expressions for all energy eigenvalues and the first few energy eigenstates are given. In addition, another solution to Gaudin's equation is also mentioned. A relation with the Calogero-Sutherland model is suggested.Publication Metadata only The effect of nanoparticles on the surface hydrophobicity of polystyrene(Springer, 2008) N/A; Department of Chemistry; Yüce, Mehdi Yavuz; Demirel, Adem Levent; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 6568The surface hydrophobicity of polystyrene-nanoparticle nanocomposites has been investigated as a function of the nanoparticle content. The addition of hydrophobically coated nanoparticles in polystyrene increased the contact angle θ of a water drop with respect to that on polystyrene surface due to change of surface composition and/or surface roughness. When the nanoparticles dispersed well in the polymer, cos θ decreased linearly with increasing amount of nanoparticles indicating a composite surface consisting of smooth polystyrene regions and rough nanoparticle regions. In case of formation of nanoparticle aggregates in polystyrene, cos θ decreased sharply at a critical concentration of nanoparticles. The observed behaviour was modeled in terms of a transition from Wenzel regime to Cassie-Baxter regime at a critical roughness length scale below which the Laplace pressure prevented the penetration of the water drop into the surface undulations. We argue that multiple length scales are needed below the critical roughness length scale to increase the contact angle further by decreasing the fraction of surface area of solid material (increasing the fraction of surface area of air) underlying the water drop.Publication Metadata only Crystal structure of bis[µ2-(3-benzimidazol-2-yl)-2-ethanethiolato-N,S,S)- chloro-palladium(II)], [(C6H4N2HCCH2CH2S)PdCl]2 C2H5OH(Walter de Gruyter GmbH, 2005) Agh-Atabay, N.M.; Borrmann, H.; Department of Chemistry; Department of Chemistry; Somer, Mehmet Suat; Haciu, Durata; Faculty Member; Teaching Faculty; Department of Chemistry; College of Sciences; College of Sciences; 178882; N/AC20H24Cl2N4OPd2S2, triclinic, P1 (no. 2), a = 8,796(1) Å, b = 9.844(1) Å, c = 14.718(2) A, α = 94.330(6)°, β = 98.546(6)°,γ = 99.258(7)°, V= 1237.3 Å3, Z= 2, Rgt(F) = 0.068, wRref(F2)= 0.142, T= 295 K.Publication Metadata only At the gates of Europe(Royal Institute International Affairs, 2003) N/A; Department of International Relations; Yılmaz, Şuhnaz Özbağcı; Faculty Member; Department of International Relations; College of Administrative Sciences and Economics; 46805Elation and disappointment are the moods of the moment in Turkey. Elation at the clearing of the political decks and the choice of a government committed to change. Disappointment at its reversal in the headlong rush to negotiate an early date for entry talks to the European Union.