Physical Sciences and Mathematics Commons^™

Annealing Effect Of Gold Thin Films On The Light Output Performances Of Organic Light Emitting Diodes, Seli̇n Piravadili Mucur, Emi̇ne Teki̇n

Turkish Journal of Physics

Gold thin films (GTFs) are transferred onto a nanostructured surface and their effects on the characteristics of organic light emitting diodes (OLED) are investigated. GTF deposition is realized by the physical vapor deposition technique under high vacuum. Globose gold nanostructures are successfully generated by annealing GTFs at different temperatures. Atomic force microscopy reveals morphological changes affected by film thicknesses and annealing temperatures. In the tailored device architecture, GTFs, [poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene are used as a hole injection layer, a hole transport layer, and an emissive layer, respectively. The performances of the fabricated OLEDs are enhanced in the presence …

Field Electron Emission Area Revisited: An Integrated Method For The Area Extraction Model, Ahmed Abdulrahman Al-Tabbakh

Turkish Journal of Physics

For electron field emitters, the emitter's physical and geometrical parameters, namely the emitter work function and its geometrical factor, are extracted from the slope of the Fowler-Nordheim (FN) plot. The literature contains few investigations and reviews of extended parameter extraction models based on the slope and intercept of the FN plot. However, due to the complexity of these reviews, there is a great need for an integrated approach to the area extraction model whereby a simplified account of the derivation and implementation of the model is presented and made convenient, especially for scholars other than physicists and engineers. This is …

Surface Effect In Explaining The Elastic Scattering Of The $\Alpha +^{12}$C System At Low Energies, Yasemi̇n Küçük

Turkish Journal of Physics

In this paper, the elastic scattering angular distributions data of the $\alpha +$12C reaction at an energy range of 13.0 to 172.5 MeV were analyzed within the framework of optical model formalism. A phenomenological deep real potential was used with a phenomenological Woods-Saxon type imaginary potential. Excellent agreement was obtained in the high-energy region. The phenomenological deep potential was unable to explain the experimental data in the low-energy region. The experimental data at both low and high energies could not be explained at the same time. In order to explain the data simultaneously at low energy and high energy, the …

Investigation Of The Influence Of Various Reflector Elements Material Types On The Core Nuclear Parameters Of The 2 Mw Triga Mark-Ii Research Reactor Using The Monte Carlo Code, Abdelaziz Darif, Abdelouahed Chetaine, Mohammed Mghar, Ouadie Kabach

Turkish Journal of Physics

The influence of variation in the kind of material of neutron reflector elements on the core neutronic parameters of the Moroccan Triga Mark-II research reactor was examined. The comparison was made between three kinds of reflector element materials: graphite, beryllium, and beryllium oxide. MCNP5 Monte Carlo computations of the effective neutron multiplication factor (${k}_{{eff}})$ of the reactor according to the number of reflector material elements inserted in the reactor core for these three reflector elements materials families were carried out. The results found could be used in order to increase the ${k}_{{eff}}$ parameter without changing the size of the reactor.

Quark Gluon Plasma And Upsilon Suppression, Rismita Ghosh, Aparajita Bhattacharya, Ballari Chakrabarti

Turkish Journal of Physics

The time-dependent suppression probability P(t) of upsilon particles has been estimated due to the screening when embedded in the medium of quark gluon plasma where the screened potential is represented by an optical potential of type $V(r,\lambda) = - [\frac{V_{0}+iW_{0}}{1+exp((r-R)\lambda)}]$. A similar type of variation of suppression probability has been obtained by others. It has been observed that $t_{\frac{1}{2}}$ for melting of $\Upsilon$ is $\sim$ 1.5 fm/c. The variation of the screening radii of heavy mesons $(J/\psi, \Upsilon)$ for 1S and 2S states with respect to plasma radius have also been investigated with the same complex screening potential. We have …

Bessel And Bessel Vortex Beams Generated By Blunt-Tip Axicon, Ramazan Şahi̇n

Turkish Journal of Physics

A theoretical prediction of the propagation characteristics of Laguerre--Gaussian beams after passing through a blunt-tip axicon is presented. An ideal axicon generates theoretically perfect diffraction-free and smooth-on-axis intensity Bessel beams, while experiments and calculations show that a zeroth-order Bessel beam deviates from its perfect behavior. Strong intensity modulation occurs due to interference around the center of the beam. The origin of these oscillations should be explored to increase the quality of beam shaping. This research shows that these oscillations can be reduced by stopping the beam center for a small portion or by optimizing input beam parameters. On the other …

A Note On Noncompact And Nonmetricit Quadratic Curvature Gravity Theories, Suat Dengi̇z

Turkish Journal of Physics

In this note, we evaluate the Weyl-invariant quadratic curvature tensors for the particular Weyl gauge field constructed in the $3+1$-dimensional noncompact Weyl-Einstein-Yang-Mills model. We subsequently extend the model to its higher curvature version. We also compute the Weyl-invariant extension of the topological Gauss-Bonnet term for this specific choice of vector field.

Predictions On Three-Particle Azimuthal Correlations In Proton-Proton Collisions, Şener Özönder

Turkish Journal of Physics

The ridge signal, which is long-ranged in rapidity, in di-hadron correlations in high-multiplicity p-p and p-A collisions opened up a whole new research area in high-energy QCD. Although the ridge had been observed in A-A collisions and interpreted as a result of the radial flow of quark-gluon plasma, it had not appeared until recently in the data of small collision systems such as p-p and p-A, nor had it been predicted theoretically or seen in event generators. There are two competing approaches that attempt to explain the systematics of the di-hadron ridge signal: hydrodynamics and gluon saturation physics (color glass …

Cycloid Experiment For Freshmen Physics Labs, Resat Akoglu, Seyedhabibollah Mazharimousavi, Mustafa Halilsoy

Turkish Journal of Physics

We establish an instructive experiment to investigate the minimum time curve traveled by a small billiard ball rolling in a grooved track under gravity. Our intention is to popularize the concept of minimum time curves anew for pedagogical reasons and to propose it as a feasible physics experiment both for freshmen and sophomore classes. The experiment is simplified enough to provide motivation for the students. We observed that even the students who were not physics majors enjoyed such a cycloid experiment.

Characterizing Decaying Dark Matter: X-Ray Emission From Sterile Neutrinos, Murat Hüdaverdi̇

Turkish Journal of Physics

Recently, an unknown emission line at E $\sim$3.5 keV from several astrophysical objects has been detected. The line is suggested to be originating from decaying dark matter particles. The results have drawn great attention from the astrophysics and particle physics community. Since the detected line is significantly weak there has also been a long debate over the origin of this mysterious signal. The most accepted scenario is a radiatively decaying sterile neutrino of 7.1 keV in mass producing a monochromatic 3.5 keV line, which is observable in X-ray energy ranges. The problem has not been settled and further observations from …

Photon In A Cylindrical Resonant Cavity, Cavi̇t Teki̇nçay, Yusuf Sucu

Turkish Journal of Physics

In this study, the massless and massive spin-1 particle equations, derived from the excited states of the zitterbewegung model, are considered for the photon in the cylindrical resonant cavity background. The resonant frequencies of the particles are also obtained. We show that these frequencies become equivalent in the $M^{2}\to 0$ limit.

Stephen Hawking - A Great Mind (8 January 1942 -- 14 March 2018), Mukhtar Ahmed Rana

Turkish Journal of Physics

Hawking induced a knowledge revolution in theoretical physics. His bedrock concepts and explanations reshaped modern physics.

Nature Of Entropy In A Scalar-Tensor Theory Of Gravity, Onur Siğinç, Mustafa Salti, Hi̇lmi̇ Yanar, Oktay Aydoğdu

Turkish Journal of Physics

This work is devoted to studying the generalized nature of the entropy function in a specific form of the scalar-tensor-vector (STeVe) theory of gravity for the Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime in the state of thermal equilibrium. For this purpose, we define an equilibrium picture of thermodynamics by making use of a suitable set of the dark energy density and dark pressure descriptions, which defines an energy-momentum tensor obeying the local energy conservation law. Furthermore, we also discuss our results numerically in order to get additional implications.

Lattice Calculations For Two-Component Fermion Systems With Unequal Masses: Onedimension, Serdar Elhatisari

Turkish Journal of Physics

We consider systems of two-component fermions with unequal masses and interacting via a short-range attractive potential. We discuss the case where the two-component fermions form a shallow dimer with large scattering length. The three-fermion and four-fermion systems with such properties are universal and characterized by the twofermion scattering length aff and the ratio of the mass of spin-↑ fermion to the mass of spin-↓ fermion, m↑/m↓. In this study, using lattice effective field theory, we analyze fermion-dimer and dimer-dimer systems and calculate the universal fermion-dimer and dimer-dimer scattering lengths for various values of the mass ratio m↑/m↓. We find that …

Isotopic Distribution In Projectile Fragments Above The Coulomb Barrier, Ayşegül Kaya, Ni̇hal Büyükçi̇zmeci̇, Riza Oğul

Turkish Journal of Physics

We have studied fragmentation properties of projectiles in peripheral heavy-ion collisions within a statistical ensemble approach. Distributions of projectile fragments are calculated for the reaction systems 86Kr on 58;64Ni and are compared to the experimental data for the same reactions at projectile energy of 15 MeV/nucleon. We assume that the projectile nuclei capture many neutrons from the targets as a result of the multinucleon transfer reactions (direct and fast reactions) at the first step of the dynamical stage of the collisions, and then the excited spectators are formed during the preequilibrium process (multistep reactions) long before the statistical equilibrium stage, …

Lattice Modeling Of A Real Gas Revisited, Lisha Damodaran, Udayanandan Kandoth Murkoth

Turkish Journal of Physics

The spin-half Ising model has been used with remarkable success in describing magnetism and phase transition in magnetic materials. Likewise, the lattice gas model, which uses the spin-1 Ising model, was employed to investigate the phase transition in liquid-gas systems. In all the earlier lattice gas models, the kinetic energy of atoms occupying the various lattice sites were not considered for finding the equation of state. In this paper we use the Hamiltonian with kinetic energy and a modified equation of state is obtained. The isotherms of this model show the behavior of real gases at all pressures and they …

High Density Equation Of State And Condensation Of Ideal Bose Gas Using Mayer'sgenerating Function, Suresh Thelakkadan Puthiyaveettil, Udayanandan Kandoth Murkoth

Turkish Journal of Physics

The equation of state of an ideal collection of bosons in the low-density and high-density regime are found using the method of cluster expansion with Mayer's generating function. The saturation density and the other thermodynamic properties are calculated by the application of Mayer's convergence of the partition function. By calculating the value of saturation density from the singularity of the partition function series, the differences between the Mayer series convergence and the virial series convergence for ideal bosons are also established.

Modeling Of A Sessile Droplet With The Curvature Dependence Of Surface Tension, Sergo Rekhviashvili, Aslan Sokurov

Turkish Journal of Physics

In this paper, using the Gibbs dividing surface method, the formula that determines the curvature-dependent surface tension in a system with two phases is deduced. The well-known Tolman formula is a special case for this formula. The problem of a sessile droplet is considered. The Bashforth-Adams equation analogue in view of the curvaturedependent surface tension is obtained and the numerical solution of the equation is carried out. We show that if the droplet size is not so large compared to the thickness of the surface layer (micro- or nanodroplets), the dependence of the surface tension on the curvature is very …

The Field Blocking On The Interface With Nonlinear Response Between Nonlinearfocusing Media, Sergey Savotchenko

Turkish Journal of Physics

We consider the nonlinear nonsymmetrical spatially distributed excitations near the thin layer with nonlinear properties separated with two media with Kerr-type focusing (positive) nonlinearity. We use the nonlinear Schrödinger equation with nonlinear potential containing two parameters to describe the new types of nonlinear stationary states. The problem is reduced to the solution of nonlinear Schrödinger equations on half spaces with the nonlinear boundary conditions at the interface plane. We obtain and analyze the two types of nonlinear excitations describing the effect of the field blocking passing through the interface into one half-space from another one. The field blocking effect is …

Multiple-Line Study Of Molecular Gas In Spiral Galaxy Ngc 2903, Selçuk Topal

Turkish Journal of Physics

Multiple molecular lines with radiative transfer modeling are a powerful tool to probe the physics of starforming gas in galaxies. We investigate the gas properties in the center of spiral galaxy NGC 2903 using low-J CO lines, i.e. 12CO(1-0), 12CO(2-1), 12CO(3-2), 13CO(1-0), and HCN(1-0). We apply a nonlocal thermodynamic equilibrium radiative transfer code to derive beam-averaged molecular gas properties. We use two methods (i.e. X2 minimization and likelihood) to define the best model representing the observed line ratios best. The line ratio diagnostics suggest that CO gas in the center of NGC 2903 is thinner and the dense gas fraction …

A Phenomenological Calculation For W+W- Diboson Production For The Largehadron Collider And Future Circular Collider, Kamuran Di̇lsi̇z, Hasan Oğul

Turkish Journal of Physics

The Large Hadron Collider (LHC) at CERN has been designed to collide beams of protons at 7, 8, 13, and 14 TeV center-of-mass energies and a new hadron collider called the Future Circular Collider (FCC), which is larger and more energetic than the LHC, is being planned for the near future. The maximum planned energy for FCC is 100 TeV center-of-mass energy. In this regard, we present the leading order and next-to-leading order cross-section predictions of two simultaneously produced opposite-sign W bosons at 7, 8, 13, 14, and 100 TeV center-of-mass energies by using the MCFM MC generator. The results …

Effect Of Al And Ga Codoping On The Morphological, Electronic, And Opticalproperties Of Zno Transparent Conductive Thin Films Prepared By Spray Pyrolysistechnique, Worapot Sripianem, Ratchatee Techapiesancharoenkij

Turkish Journal of Physics

Codoping a semiconductor thin film with two or more dopants is a feasible technique to improve the electrical properties of the thin film. In this work, we studied the codoping of Al and Ga n-type impurities in a ZnO film (AGZO) deposited on a glass substrate by the spray pyrolysis method. The total doping concentration, [Al + Ga]/[Al + Ga + Zn], was 5 at.% with varying Al:Ga codoping proportions of 0:5, 1.25:3.75, 2.5:2.5, 3.75:1.25, and 5:0 at.%. The effect of Al/Ga codoping on the structural, texture, morphological, optical, and electrical properties of the AGZO films were investigated using X-ray …

On The Domination Chain Of M By N Chess Graphs, Kathleen Johnson

Murray State Theses and Dissertations

A survey of the six domination chain parameters for both square and rectangular chess boards are discussed.

Identification Of Chemical Compounds That Inhibit The Function Of Histidyl-Trna Synthetase From Pseudomonas Aeruginosa, Yanmei Hu, Stephanie O. Palmer, Sara Robles, Tahyra Resto, Frank Dean, James M. Bullard

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Pseudomonas aeruginosa histidyl-tRNA synthetase (HisRS) was selected as a target for antibiotic drug development. The HisRS protein was overexpressed in Escherichia coli and kinetically evaluated. The KM values for interaction of HisRS with its three substrates, histidine, ATP, and tRNAHis, were 37.6, 298.5, and 1.5 μM, while the turnover numbers were 8.32, 16.8, and 0.57 s-1, respectively. A robust screening assay was developed, and 800 natural products and 890 synthetic compounds were screened for inhibition of activity. Fifteen compounds with inhibitory activity were identified, and the minimum inhibitory concentration (MIC) was determined for each against a panel of nine pathogenic …

Improving The Ability To Study Coastal Nutrient Dynamics Through The Development Of High-Resolution Water Samplers, Kyle Neumann

Link Foundation Ocean Engineering and Instrumentation Fellowship Reports

Globally, marine ecosystems are experiencing fundamental shifts in their structure and function. Due to the high level of interconnectedness between aquatic organisms and their environment, they are highly sensitive to changes in water chemistry. For example, coral reefs thrive in water that generally contains very low concentrations of macronutrients such as nitrogen and phosphorus.1 An increase in these compounds as a result of human activities on land can have drastic impacts on coral health.2 In order to fully understand the cycling, fates and impacts of chemical compounds in the marine environment, it is critical to collect concentration data on the …

A Grounded Theory Of Emergent Leadership In Nonhierarchical Virtual Teams, Randall Fleming

Walden Dissertations and Doctoral Studies

A Grounded Theory of Emergent Leadership in Nonhierarchical Virtual Teams

by

Randall David Fleming

MS, Colorado Technical University, 2008

BA, The Ohio State University, 1984

Dissertation Submitted in Partial Fulfillment

of the Requirements for the Degree of

Doctor of Philosophy

Management

Walden University

November 2018

Strategies For Improving Energy Conservation On A Military Installation, Samuel Francis Richardson

Walden Dissertations and Doctoral Studies

Energy is an essential component required to execute missions throughout military organizations. Failing to sustain energy efficiency in military units could cause mission failures throughout the Department of Defense. As a result, efficient energy management has become a major priority for Air National Guard units as well as other military organizations around the globe. The purpose of this qualitative single case study was to gain an understanding of strategies used by front-line military supervisors to reduce energy consumption through behavioral change on a military installation located in Maryland. The central question explored strategies that front-line military supervisors use to change …

Analytic Extensions To The Data Model For Management Analytics And Decision Support In The Big Data Environment, Nsikak Etim Akpakpan

Walden Dissertations and Doctoral Studies

From 2006 to 2016, an estimated average of 50% of big data analytics and decision support projects failed to deliver acceptable and actionable outputs to business users. The resulting management inefficiency came with high cost, and wasted investments estimated at $2.7 trillion in 2016 for companies in the United States. The purpose of this quantitative descriptive study was to examine the data model of a typical data analytics project in a big data environment for opportunities to improve the information created for management problem-solving. The research questions focused on finding artifacts within enterprise data to model key business scenarios for …

Employee Retention Strategies In The Information Technology Industry, Corey Harris

Walden Dissertations and Doctoral Studies

Productivity declines when employees voluntarily leave an organization. The purpose of this case study was to explore strategies that business leaders use to reduce turnover among their skilled information technology (IT) professionals in the Dallas-Fort Worth area. Six business leaders were selected because they had implemented strategies to retain skilled IT professionals. Herzberg's 2-factor theory was the conceptual framework for this doctoral study. Data were collected from semistructured interviews and review of the organization's policies, procedures, and personnel handbook. Data analysis consisted of assembling the data, organizing the data into codes, compiling the data into themes, and interpreting and disclosing …

Strategies For Successfully Managing Organizational It Projects, Joseph Rathbun

Walden Dissertations and Doctoral Studies

Over 70% of information technology (IT) projects in large organizations in the United States run over budget or fail to reach completion primarily due to a lack of effective strategies. The purpose of this single case study was to explore strategies that IT project managers used to successfully complete IT projects. Hersey and Blanchard's situational leadership theory was the conceptual framework. Purposive sampling method was used to identify 2 successful IT project managers in Central Texas. Data gathered from semistructed interviews and collected from publicly available documents were analyzed using coding techniques, constant comparison, and key word phrases. Member checking …