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Güngör Gündüz

Güngör Gündüz
Orta Dogu Teknik Universitesi (Middle East Technical University), Ankara, Turkey

Doctor of Philosophy

About

116
Publications
26,246
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1,376
Citations
Citations since 2016
14 Research Items
761 Citations
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120
2016201720182019202020212022020406080100120

Publications

Publications (116)
Article
The structures of eight BEATLES songs were characterized by using the fundamental concepts of statistical physics, thermodynamics, and viscoelastic theory. The Shannon entropy, negentropy, order, topological entropy, fractal dimension, network properties, and conservative and dissipative energies were found for all songs. The sequential entropy cha...
Article
The historical change of Gross Domestic Product per capita (GDP) values of countries with the thirty largest economies was analyzed by using different entropies, (i) topological entropy, (ii) Shannon entropy, and (iii) configurational entropy. Topological entropy was used to analyze the number of periodic points of each ranking, and five segments c...
Article
Full-text available
Mica-titania pearlescent pigments (MTs) were previously coated with organic molecules to obtain combination pigments (CPs) for achieving certain improvements or functionalities. Anthocyanins (ACNs) are molecules that can be extracted from natural resources and exhibit color changes via pH modifications of the enclosing medium. The purpose of the st...
Article
Full-text available
The dynamics of financial systems depends not only on Brownian motion but also on wave-like behavior of fluctuations. Statistical mechanics and viscoelastic theory were used to elucidate it by using the daily data of S & P-500 from 1986 to 2019. The viscoelastic behavior of asset values or stock market index can be studied within the basis of "caus...
Article
Full-text available
The purpose of this research is to characterize shapes in thermodynamic terms, namely, in terms of total energy, dissipative energy, entropy, and temperature. As case studies, polygons and some well-known curves were taken, and they were characterized using physical terms. The relation between entropy and curvature was elucidated, and the black hol...
Article
Purpose The purpose of this paper is to enhance the limited fluorescence of mica titania (MT) effect pigments by coating them with peripherally substituted zinc phthalocyanines (ZnPc). Design/methodology/approach The effects of deposition medium, temperature, time, initial organic pigment/MT ratio on deposition behaviour and efficiencies were inve...
Article
A new methodology was introduced to investigate the pattern formation in time series systems due to their viscoelastic behavior. Four stochastic processes, uniform distribution, normal distribution, Nasdaq-100 stock market index, and a melody were studied within this context. The time series data were converted into vectorial forms in a scattering...
Article
Plate-like boehmite nanoparticles (BH) produced from aluminum hydroxide by hydrothermal process were functionalized in one step with two different diisocyanates. The amount of free isocyanates that were available for polymerization reaction was determined to be higher in functionalization with the aromatic diisocyanate (diphenylmethane-4,4′-di-isoc...
Article
In this study, a new hybrid alkyd resin was formulated using melamine-based hyperbranched polymer having 24 hydroxyl groups on its structure and relatively low molecular weight alkyd. The alkyd was synthesized using an oil mixture (40% linseed + 60% sunflower). Melamine was used as the core molecule for the hyperbranched polymer due to its excellen...
Article
The viscoelastic and thermodynamic properties of four stock indices, namely, DJI, Nasdaq-100, Nasdaq-Composite, and S&P were analyzed for a period of 30 years from 1986 to 2015. The asset values (or index) can be placed into Aristotelian ‘potentiality-actuality’ framework by using scattering diagram. Thus, the index values can be transformed into v...
Article
A parametric study was carried out to investigate the effects of process parameters on the properties of opaque and/or colored polymer pigment. The core was synthesized using methyl methacrylate (MMA), methacrylic acid (MAA), and ethylene glycol dimethacrylate, and the shell from styrene. The surfactant/water (S/W) ratio was changed between 0.56 an...
Article
A new generation multihollow opaque polymer pigment was synthesized by suspension polymerization of "water-in-oil-in-water" emulsion method, where methyl methacrylate and ethylene glycol dimethacrylate monomer mixture was used as oil phase. The effects of surfactant and cosurfactant composition in terms of "hydrophilic/lipophilic balance" on the st...
Article
The rise of empires can be elucidated by treating them as living organisms, and the celebrated Verhulst or Lotka–Volterra dynamics can be used to understand the growth mechanisms of empires. The fast growth can be expressed by an exponential function as in the case of Macedonian empire of the Alexander the Great whereas a sigmoidal growth can be ex...
Article
The dynamics of stock market systems was analyzed from the stand point viscoelasticity, i.e. conservative and nonconservative (or elastic and viscous) forces. Asset values were modeled as a geometric Brownian motion by generating random Wiener processes at different volatilities and drift conditions. Specifically, the relation between the return va...
Article
Full-text available
The well-known Le Chatelier principle in chemistry describes how a system behaves when subject to an external effect. The way this principle works in conservative and dissipative systems was discussed within the framework of phase space. The Le Chatelier principle was restated in a more generalized form in such a way that it now becomes an underlyi...
Chapter
Full-text available
Melodies can be treated as time series systems with the pitches (or frequencies of the notes) representing the values in subsequent intervals. The pattern of a melody can be revealed in a scattering diagram where pitches represent vertices, and the directed pathways which connect the former pitches to the next ones signify the relations established...
Article
Full-text available
We utilize the physical properties of a hypothetical molecular schema giving rise to an autocatalytic biosphere. A key concept is the driving of terrestrial life as a parametric oscillation: i.e. that the biosphere behaves fundamentally as an oscillatory system into which solar energy is diurnally deposited. The schema, containing 'A, B and C' type...
Article
Full-text available
This study focuses on the synthesis and characterization of different generations (G0–G7) of polyamidoamine (PAMAM) dendrimer-coated magnetic nanoparticles (DcMNPs). In this study, superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method. The synthesized nanoparticles were modified with aminopropyltrimethoxysilane for...
Article
Combination pigments were synthesized by the deposition of copper phthalocyanine and tetracarboxamide copper phthalocyanine on a mica-titania pigment in dimethyl formamide solvent to improve color properties. The FT-IR and XRD analyses were performed to observe the crystal transformations of the pigments on the substrate. The stable beta form of co...
Article
Full-text available
The chitosan-coated magnetic nanoparticles (CS MNPs) were in situ synthesized by cross-linking method. In this method; during the adsorption of cationic chitosan molecules onto the surface of anionic magnetic nanoparticles (MNPs) with electrostatic interactions, tripolyphosphate (TPP) is added for ionic cross-linking of the chitosan molecules with...
Article
A methodology was developed to analyze relation-based systems evolving in time by using the fundamental concepts of thermodynamics. The behavior of such systems can be tracked from the scattering matrix which is actually a network of directed vectors (or pathways) connecting subsequent values, which characterize an event, such as the index values i...
Article
In this work, ZrW2O8–ZrO2 core–shell composite particles were synthesized. ZrW2O8 that was used in the core is a material with negative coefficient of thermal expansion, and it was synthesized from a high-pH precursor based on use of tungstic acid and zirconium acetate. Shell layer was composed of ZrO2 nanocrystallites and precipitated from an aque...
Article
The synthesis of mica-titania special effect pigment and the effect of rutile promoting additive, tin dioxide (SnO2), on the phase transformation of titanium dioxide (TiO2) were investigated. SnO2 coating with variable thicknesses on sieved and pre-treated muscovite mica prior to TiO2 coating yields a pearlescent pigment with higher rutile-to-anata...
Article
Full-text available
In the present study, silver nanoparticles were produced by hydrazine hydrate and oleylamine/oleic acid systems in order to investigate the effects of reducing agents with different strengths on the reduction mechanism. Particle size and size distribution of silver particles produced by slow reducing system were studied in detail by using transmiss...
Article
Full-text available
The importance and different aspects of autocatalysis in evolution was analyzed. The behaviour of autocatalytic reactions mainly the Lotka-Volterra and the Schlögl equations were discussed in terms of phase change, entropy, and their oscillation frequency. The increase of complexity as the general direction of evolution was examined on some pattern...
Article
The scattering diagram of a stock index results in a complex network structure, which can be used to analyze the viscoelastic properties of the index. The change along x- or y-direction of the diagram corresponds to purely elastic (or spring like) movement whereas the diagonal change at an angle of 45° corresponds to purely viscous (or dashpot like...
Article
A zirconium tungstate (ZrW2O8) precursor was synthesized by a novel sol-gel method with zirconium oxychloride and tungstic acid as the zirconium and tungsten sources, respectively. Heat treatment at 600oC for 10 hours was adequate to crystallize the precursor. Use of excess zirconium source and the concentration of hydrochloric acid were found to a...
Article
Nylon 6 is a widely used engineering polymer, and has relatively poor impact strength. Ethylene, n-Butyl acrylate, maleic anhydride (E-nBA-MAH) terpolymer is blended with Nylon 6 to enhance its impact strength. Mixture should be compatible to be used in applications. The bare interaction energy between Nylon 6 and E-nBA-MAH terpolymer is calculated...
Article
Full-text available
The impact strength of Nylon 6 can be further improved by blending it with ethylene-butyl acrylate-maleic anhydride elastomer. The blending is achieved in solution phase. Due to incompatibility of Nylon 6 and the elastomer, a special mixture of solvents is used to dissolve both components. The solution is electrospun, and the effects of the process...
Article
In recent years nano-sized dendrimer/hyperbranched polymers gained importance in drug delivery applications. In this study, a novel fatty acid-based hyperbranched resin (HBR) was synthesized and used for tamoxifen (TAM) and idarubicin (IDA) delivery. The core of the HBR was dipentaerythritol, and the branching was provided by dimethylolpropionic ac...
Article
A network was characterized by its viscoelastic properties. The viscoelastic property indicates the deformations or changes in the shape and in the internal structure during the evolution of a network. The change in the direction of motion was taken as elastic deformation and the change in the vertical direction as viscous deformation. These deform...
Article
Immersion of electrospun polycaprolactone (PCL) nanofiber mats in calcium phosphate solutions similar to simulated body fluid resulted in deposition of biomimetic calcium phosphate layer on the nanofibers and thus a highly bioactive novel scaffold has been developed for bone tissue engineering. Coatings with adequate integrity, favorable chemistry...
Article
Full-text available
Zirconium tungstate (ZrW2O8) is a ceramic that shows a large isotropic negative thermal expansion over a wide range of temperatures. This unique property makes it an interesting candidate for such applications in which thermal expansion mismatch between components constitutes a problem. A novel precursor for ZrW2O8 made from relatively cheaper and...
Article
Full-text available
In this research work, a graph theoretical approach has been introduced to find a mathematical model for the change of hardness of weakly cross-linked polymer network systems with the change of configurations. The polymers studied are (i) poly(methyl methacrylate), (ii) styrene–acrylonitrile copolymer and (iii) polystyrene. In very weakly cross-lin...
Article
In this study, water dispersed paints were produced using polyester polyol, isophorone diisocyanate (IPDI) and hydrophilic monomers. Two sets of experiments were performed. In the first group, the effects of various proportions of the hydrophilic monomers dimethylol propionic acid (DMPA) and tartaric acid (TA) on the state of dispersion, physical,...
Article
In this research, diazophenylene bridged metal-phthalocyanine (Pc) polymers were produced from diazonium salt of 1,4-diaminophenylene and presynthesized 1,8,15,22-tetraamino metal-Pcs. 1,8,15,22-Tetraamino metal-Pc complexes of Co, Ni, Cu, Ce, and Er were obtained by reducing 1,8,15,22-tetranitro metal-Pc complexes synthesized from 3-nitrophthalic...
Article
In this research hyperbranched resins containing fatty acid residues were synthesized. Dipentaerythritol which has six hydroxyl groups was used as the core molecule, and it was transesterified with (i) castor oil, and (ii) a mixture of castor oil and linseed oil at 240°C. The resulting molecule had hydroxyl containing ricinoleic acid residue coming...
Article
The movement of topological or deformable surfaces was shown to create a helicoid surface. The description of dynamics in the parametric space of helicoid introduces a new understanding to quantum mechanics and field theory. The different equations of quantum mechanics can be obtained from a general equation of motion derived from helicoidal dynami...
Article
The dynamics of world terror and the war in Iraq were studied from different aspects. World terror displays a scaling growth while the rate equations of the civilian and the US-soldier casualties in Iraq both display zero-order chemical kinetics. The fractal dimensions of scattering diagrams were evaluated. Animal diagrams were obtained from scatte...
Article
Full-text available
Alumina borosilicate/polyvinylalcohol (PVA) composite nanofibres were prepared by the sol-gel method and electrospinning technique. Effects of solution viscosity, applied voltage, capillary tip to metal collector distance and calcination temperature were evaluated by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectr...
Article
SYNTHESIS, CHARACTERIZATION, AND ELECTRICAL PROPERTIES OF DIAZOPHENYLENE AND DIAZODIPHENYLENE BRIDGED Co, Ni, Cu, Ce, AND Er PHTHALOCYANINE POLYMERS Alkan, Cemil M. Sc., Department of Polymer Science and Technology Supervisor: Prof.Dr. Leyla Aras Co- Supervisor: Prof.Dr. Güngör Gündüz September 2004, 112 pages In this research, diazophenylene and d...
Article
Full-text available
Chaos theories developed in the last three decades have made very important contributions to our understanding of dynamical systems and natural phenomena. The meaning of chaos in the current theories and in the past is somewhat different from each other. In this work, the properties of dynamical systems and the evolution of chaotic systems were dis...
Article
Carbon nanotubes (CNTs) were synthesized by using a plasma based electron beam generator, which has a fast filamentary discharge formed from the superposition of an ordinary low-pressure dc glow and a high-current pulsed discharge. To our knowledge, CNTs are synthesized for the first time by this method. Acetylene was used as the carbon source and...
Article
The size distribution of three-dimensional loops in a network structure influences the hardness of polymers. A narrow size distribution results in larger hardness than a broad distribution of the same average size. The loop size distribution can be changed by late addition of the cross-linker. In this work the change of hardness with temperature of...
Article
In 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...
Article
The mathematical structures of six songs were studied by treating them as complex systems. The studies were based on (i) scattering diagram, (ii) spiral structure, (iii) graph theory and animal diagrams, and (iv) entropy and organization. In (i), the fractal dimension and the radius of gyration was determined for each melody. In (ii), it was shown...
Article
In this research, a conventional propylene glycol-based unsaturated polyester is synthesized and modified with diphenylmethane-4,40-diisocyanate (MDI), which leads to the formation of a hybrid polymer network (HPN). The effect of this modification on the mechanical properties is studied experimentally. The optimum molar ratio of MDI to unsaturated...
Article
Full-text available
A novel type of phthalocyanine polymer, 1,4-diazophenylene-bridged Cuphthalocyanine, was prepared from the diazonium salt of diaminobenzene and Cu(II) 1,8,15,22-tetraaminophthalocyanine. The polymer is partially soluble in tetrahydrofuran, dichloromethane, and dimethylformamide. Characterization of the polymer was performed by IR and UV-visible spe...
Article
New water-borne polyurethane resins were produced using maleinized monoglyceride (MMG), hydroxyl-terminated polybutadiene (HTPB), toluene di-isocyanate, and ethylene diamine (EDA). Maleinization was performed in order to insert hydrophilic groups in the fatty acid residues, which were then inserted to the backbone of polyurethane. The MMG was mixed...
Article
In this research, a flame-retardant water-dispersed polyurethane resin was synthesized through incorporating phosphonate groups into the polyurethane structure in the chain-extension step. A phosphorus-containing reactive flame-retardant compound was synthesized for this purpose. First, bis(4-nitrophenyl)phenyl phosphine oxide was synthesized and t...
Article
Phosphorus-containing flame retardant water-dispersed polyurethane coatings were produced by incorporating different amounts of a phosphorus compound onto the polyurethane main chain. The novel phosphorus containing compound (phosphorus phenyl dihydroxy) was synthesized in three steps using benzaldehyde, pentaerythritol, phenyl phosphonic dichlorid...
Article
Air-dried water-dispersed polyurethane resins were produced from poly(propylene-ethylene) copolymer triol, monoglyceride, toluene diisocyanate, and tartaric acid. Monoglyceride and poly(propylene-ethylene) copolymer triol were employed at different ratios, with the monoglyceride ranging between 50–70% of the total polyol used, and the isocyanate/hy...
Article
In this work, mathematical models for the growth of the Ottoman and Roman Empires are found. The time interval considered for both cases covers the time from the birth of the empire to the end of the fast expansion period. These empires are assumed to be nonlinearly growing and self-multiplying systems. This approach utilizes the concepts of chaos...
Article
The mechanical properties of polymer network structures depend mostly on the network rigidity. In very weakly cross-linked systems, entanglements also play a predominant role in the mechanical properties, especially hardness; and the contribution of entanglements competes with the contribution of the network rigidity. The entanglement and the netwo...
Article
Full-text available
Pure uranium dioxide and uranium dioxide-gadolinium oxide (5 and 10%) fuels used in this study were prepared by the solution-gelation (sol-gel) technique. The fuels were then coated with boron carbide by chemical vapor deposition. Boron carbide was produced from the reaction of carbon tetrachloride and boron trichloride with excess hydrogen, in a t...
Article
In this study, water-borne polyurethane resins were produced using poly(propylene-ethylene) copolymer triol, toluene diisocyanate, and hydrophilic monomers, dimethylol propionic acid and tartaric acid. The hydrophilic monomers were used separately. In either case, the ratio of isocyanate functional groups to the sum of hydroxyl groups of polyol and...
Article
In this research the burnup performance of (1) boron nitride (BN) and (2) boron nitride-boron (B), hybrid coated urania (UO2) and urania-gadolinia (Gd2O3) fuels were studied. The behavior of fuel burnup, depletion of BN and B, the effect of coating thickness and also Gd2O3 content on the burnup performances of the fuels were found by using the code...
Article
The concept of a fractal dimension that characterises the nonlinear growth of very intricate dynamics of biological, chemical, and physical systems was utilized to model an old empire as a social system. The fractal concept has been applied to model the growth of the Ottoman Empire. It was shown that her growth has a fractal dimension equal to gold...
Article
Uranium dioxide-only and uranium dioxide–gadolinium oxide (5% and 10%) ceramic nuclear fuel pellets which were already coated with boron nitride were coated with thin boron layer by chemical vapor deposition to increase the burn-up efficiency of the fuel during reactor operation. Coating was accomplished from the reaction of boron trichloride with...
Article
Halogenation and addition of some heavy metallic oxides have been in use for a few decades to impart flame-retarding properties to polymers. In this study bromine was added to the polymer (polyester of propylene glycol + phthalic anhydride) by means of decabromodiphenyloxide (DBDPO) at varying concentrations. In addition to bromine, 2% antimony oxi...
Article
In this research long oil alkyd resin, and styrenated alkyd resin were made flame retardant by the incorporation of (i) bis-pyridine bis-tribromophenoxo copper (II) complex, and (ii) polydibromo-phenylene oxide (PDBPO). The former was synthesized in the laboratory, and the second one was obtained from the decomposition of the complex. Both of these...
Chapter
This chapter provides an overview of processing of unsaturated polyesters. Unsaturated polyesters (UPs) are composed of prepolymers with some unsaturation on the backbone and a vinyl monomer. The prepolymer is obtained from the interaction of saturated and unsaturated dibasic acids with dihydric alcohols. The vinyl monomer crosslinks the unsaturate...
Article
Three nuclear fuels, pure urania, 5% and 10% gadolinia containing fuels were coated with boron nitride to improve nuclear and physical properties. Coating was done by plasma enhanced chemical vapor deposition technique by using boron trichloride and ammonia. The specimens were examined under a scanning electron microscope. Boron nitride formed a gr...
Conference Paper
Full-text available
Bu araştırmada kullanılan nükleer yakıtların üzeri B4C ile kimyasal buhar çökeltme yöntemi ile kaplanmıştır. B4C kaplanması, karbon tetraklorür ve bor triklorür ile aşırı hidrojen ortamında 1000-1175 oC'da gerçekleştirilmiştir. Yapılan deneylerde kaplama kompozisyonunun doğrudan sıcaklığın bir fonksiyonu olduğu görülmüştür. Soğuk bölgelerde daha ço...
Conference Paper
Full-text available
Bor karbür kaplı düşük zenginlikli normal takıtların, basınçlı su reaktöründe kullanılmaları durumundaki performansları, bor nitrür kaplı yakıtlarla karşılaştırmalı olarak incelenmiştir. Bor karbür kaplamanın yoğunluğu bor nitürden yüksek olduğundan aynı soğurma etkisi daha düşük kalınlıklarla elde edilebilmektedir. Fisil izotop ve güç tepesi davra...
Conference Paper
Full-text available
Doğal uranyum dioksit-gadolinyum oksit karışımı yakıt çubukları ile bor nitrür kaplı düşük zenginlikli normal yakıtların, basınçlı su reaktöründe kullanılmaları durumundaki performansları karşılaştırmalı olarak incelenmiştir. Onda bir oranında yanabilir zehirli yakıt çubuğu bulunduran yakıt demeti WIMS bilgisayar programııyla modellenerek yanmaya b...
Article
A theory was developed for the nonlinear growth of linear chains by incorporating the chain dynamics into the rate equation. This was achieved by using a modified Boltzmann equation. The chains were first divided into two groups as reacting and unreacting chains in any time interval. The contribution of reacting chains to the chain growth was accou...
Article
Full-text available
Pure urania- and urania-gadolinia-containing fuel pellets were coated with boron nitride (BN) to improve the physical and neutronic properties of the fuel. The BN coating seems to have a technological advantage over zirconium-diboride coating. The BN is chemically inert, corrosion resistant, withstands rapid temperature changes, and has a high ther...
Article
Three different fuels UO2-only, UO2-Gd2O3(5%), and UO2-Gd2O3(10%) were produced by sol-gel technique. Their powder characteristics such as flowability, BET surface area, average pore diameter, and cumulative pore volume were determined. The pore size distributions of powders, green pellets, and sintered fuels were determined by using a mercury poro...
Article
The hardness of ``late" and weakly crosslinked polymethylmethacrylate was determined experimentally. The change in hardness can be expressed by, H=h0+h kx (kx-1)(1-C)kx-2C2 where C is the fraction of cross-linker, x the number of monomer units, and kx denotes the linkages or units formed on the linear chain after the addition of cross-linker. h and...
Article
In this research the effect of acrylonitrile on styrenated alkyd resin was investigated. In addition long oil, styrenated, and acrylonitrilated paints were produced and the effect of decabromodiphenyloxide (DBDPO) on their flame retardance was studied. Acrylonitrile increased the viscosity of the resin. However it improved the flexibility and the i...
Conference Paper
Full-text available
The fuel pellets produced by sol-gel technique were coated with boron nitride. The coated samples were sintered at 1600 oC. Thermal Reactor Physics Lattice Cell code WIMS-D/4 was used in the neutronic analysis of the CANDU fuel Bundle to observe the neutronic performance of the coated fuel. Three types of fuel were considered, fuel made of natural...
Article
Full-text available
Uranium dioxide-gadolinium oxide fuel was produced by the sol-gel technique. The effects of different parameters such as calcination and reduction temperature, compaction pressure, particle size of powder, type of binder, sintering temperature, sintering atmosphere, and duration of sintering on pore size distribution were investigated. The experime...