Physical Sciences and Mathematics Commons^™

Transient Photoconductivity In Amorphous Se-Ge-Ag System, R. S. Sharma, D. Kumar, A. Kumar

Turkish Journal of Physics

Transient Photoconductivity measurements have been made in vacuum evaporated thin films of Se_{0.80 - x}Ge_{0.20}Ag_x at different intensities, temperatures and illumination times. The films exhibit long-lived residual photoconductivity, called persistent photoconductivity, with an extremely slow decay rate. The persistent photoconductivity (PPC) increases with an increase in intensity and illumination time. However, this quantity decreases with increase in temperature. These results indicate that the decay of photoconductivity is not only governed by the carrier trapped in the intrinsic defects but also gets affected by the light induced defect creation through structural changes The persistent photoconductivity effect is found to be suppressed …

Stagnation Point Flow And Heat Transfer Of A Micropolar Fluid In A Porous Medium, Hazem Ali Attia

Turkish Journal of Physics

The steady laminar flow in a porous medium of an incompressible non-Newtonian micropolar fluid impinging on a permeable flat plate with heat transfer is investigated. A numerical solution for the governing nonlinear momentum and energy equations is obtained. The effect of the porosity of the medium and the characteristics of the non-Newtonian fluid on both the flow and heat transfer is presented and discussed.

Dwba Of The Reaction ^0be(P, \Alpha )^6li At E_P = 18.6\Sim 50 Mev, S. E. Abdel-Kariem

Turkish Journal of Physics

The compound nucleus produced in the reaction ^9Be(p, \alpha)^6Li in the incident energy range E_p = 18.6 \sim 50 MeV is mainly occurred when its excitation energy is greater than the \alpha -particle threshold separation energy by about 20 MeV, strongly suggesting the reaction mechanism is a direct one-step process. To understand this phenomenon, we employ semi-microscopic zero-range distorted-wave Born approximation (DWBA) theory to analyse experimental data obtained in this energy range for the lower three ^6Li-states: ground state (1^+; 0); 2.186 MeV (3^+; 0); and 3.563 MeV (0^+; 1). The Kurath-Millener spectroscopic-factor amplitudes for the triton-cluster transfer are used …

Dimensional Crossover In Semiconductor Structures: From 3d Electron Transport To Ballistic Electrons In 1d, Karl-Fredrick Berggren

Turkish Journal of Physics

Modern semiconductor technologies have made possible special devices in which a gradual dimensional crossover may be induced by means of applied electric fields. Two specific examples are described. The first one is a special GaAs field effect transistor in which the thickness of the active electron gas layer may be varied by external voltages. With decreasing layer thickness transverse states become quantized and by depopulating the corresponding subbands a tunable dimensional crossover from 3D to 2D is achieved. The second example describes how a 2D to 1D crossover may be obtained in high-mobility split-gate GaAs/AlGaAs heterostructures. Effects of interactions in …

Self-Assembled Nano-Structures On The Icosahedral Al-Pd-Mn Quasicrystal, Mehmet Erbudak, Jean-Nicolas Longchamp, Yves Weisskopf

Turkish Journal of Physics

A quasicrystal is a solid with an aperiodic atomic distribution, but displaying discrete diffraction pattern. At an interface where an ordinary crystal and a quasicrystal intersect, the lack of commensurability between the structures leads to misfits on atomic scale resulting in a wealth of novelties. Here, we present experimental observations on three essentially different cases: Al, Fe, and Si ultra-thin layers grown in vacuum on the pentagonal surface of an icosahedral Al-Pd-Mn quasicrystal. In all three cases, the growing layer decays into nm-size islands. Al is the major alloy component of the substrate material and provides a natural tool to …

Computational Studies On Mechanical Properties Of Carbon Nanotori, Tahi̇r Çağin, Guanghua Gao, William A. Goddard Iii

Turkish Journal of Physics

Carbon has diverse structures, especially (0-dimensional) fullerenes, (1-dimensional) tubes have generated great interest among scientists and technologists. Studies of the structures and properties of these low dimensional carbon molecules show tremendous potential for use in nanoscale device applications. Motivated by these exciting possibilities in finding new forms of carbon materials and their potential applications, we have designed hypothetical single wall carbon nano-toroids. Carbon toroids are also ideal in studying the elastic and plastic deformation behavior of nanotubes under bending loads. We can accurately correlate the behavior of the tubes to its uniform curvature. In this particular work we focused on …

Relativistic Density Functional Theory Method: Applications To Autoionization States Of Atoms, Şaki̇r Erkoç

Turkish Journal of Physics

A brief introductory information about the accurate atomic calculations using Density Functional Theory has been reviewed. How relativistic effects can be considered in atomic calculations through the density functional theory has been discussed. Some sample calculation results for the autoionization states of the neutral and cationic atoms have been presented.

Tkachenko Modes Of The Square Vortex Lattice In A Two-Component Bose-Einstein Condensate, M. Keçeli̇, M. Ö. Oktel

Turkish Journal of Physics

We study Tkachenko modes of the square vortex lattice of a two-component Bose-Einstein condensate (BEC) in the mean-field quantum Hall regime, considering the coupling of these modes with density excitations. We derive the hydrodynamic equations and obtain the dispersion relations of the excitation modes. We find that there are two types of excitations, gapped inertial modes and gapless Tkachenko modes. These modes have two branches which we call acoustic and optical modes in analogy with phonons. The former has quadratic while the latter has linear wave-number dependence in both inertial and Tkachenko modes. Acoustic Tkachenko mode is found to be …

Applications Of Genetic Algorithm To Quantum Mechanical Systems, Mehmet Şahi̇n, Ülfet Atav, Mehmet Tomak

Turkish Journal of Physics

Genetic algorithm (GA) inspired by the biological world is a general search and optimization method. It was first proposed by Holland in 1975. GA has been applied to many scientific areas especially in engineering optimization problems. It is also used in solving of quantum mechanical problems. In this study, we have applied this method to different realistic quantum mechanical problems of both self-consistent and non-self-consistent type. The results obtained are compared with the results of other methods and it is seen that the GA can be a very powerful alternative to some other traditional techniques such as variational method.

First Principles Approach To Batio_3, Mustafa Uludoğan, Tahi̇r Çağin

Turkish Journal of Physics

We present state of art first-principles study on the static and dynamic properties of BaTiO_3, a typical ferroelectric material. Here, structure, equation of state, phase stability, and phase transformations of BaTiO_3 studied in Generalized Gradient Approximation. Furthermore, properties such as, Born effective charges, optical dielectric constant and phonon spectra are calculated from Density Functional Perturbation Theory.

A Molecular Dynamics Study Of The Static Structure, Thermodynamic And Transport Properties Of Liquid Iron Using The Modified Analytic Embedded Atom Method, Serap Şentürk Dalgiç, İbrahi̇m Koçoğlu

Turkish Journal of Physics

Using the modified analytic embedded atom method (MAEAM), we have carried out molecular dynamics (MD) simulation to compute structure,thermodynamic and transport properties of liquid iron. The Foiles type effective pair potential based on the MAEAM potential functions proposed by Quyang and co-workers are shown to predict the pair distribution function well near its melting. The calculated thermodynamic properties such as, the internal energy, Helmholtz free energy and entropy are in a good agreement with experimental data. The results for the computed self-diffusion coefficients are in reasonable agreement with experiments and other works.

Self-Diffusion Coefficients In Liquid Ag Using The Embedded Atom Model Based Effective Pair Potentials, Seyfetti̇n Dalgiç, Mutlu Çolakoğullari

Turkish Journal of Physics

We present the dynamical properties of liquid Ag at different temperatures, using the Mishin and Doyoma-Kagure version of the Embedded Atom Model (EAM) potentials. They have been evaluated within the framework of the mode-coupling theory, using a self-consistent scheme that uses as input data only the static structure functions and the interatomic pair potentials of the liquid Ag. We have computed single-particle and collective time dependent properties of liquid Ag, and thereby calculated its self-diffusion constants. We have also discussed our results comparing with both experimental data and results of molecular dynamic simulation.

Molecular Dynamics Study Of Thermal Properties Of Intermetallic Alloys, H. H. Kart, Mehmet Tomak, Tahi̇r Çağin

Turkish Journal of Physics

Molecular dynamics simulations of bulk copper, gold pure metals and their ordered intermetallics alloys of Cu_3Au(L1_2) and CuAu_3(L1_2) have been carried out between above 0 K and below the their melting points of the materials for predicting their temperature-dependent thermophysical properties. The effects of temperature and concentration on the physical properties such as enthalpy, volume, heat capacity, thermal expansion and density of Cu_xAu_{1-x} are studied. Especially, temperature-dependent polynomial functions of enthalpy, volume and density are obtained. Sutton-Chen (SC) and Quantum Sutton-Chen (Q-SC) many-body potentials are used in the constant enthalpy-constant pressure ensemble (HPN) and constant pressure-constant temperature ensemble (TPN). Three …

Effect Of A Finite Number Of Electrons On The Physical Properties Of Two Dimensional Parabolic Quantum Dot, Berna Gülveren, Ülfet Atav, Mehmet Tomak

Turkish Journal of Physics

The effect of number of particles on the physical properties of a two dimensional parabolic quantum dot system is investigated numerically at finite temperature. The Thomas-Fermi equation is solved self consistently with Poisson equation. The changes induced by electron-electron interaction are also analyzed. It is shown that the numerical procedure that is applied to solve the problem is very efficient at all temperatures.

Molecular Dynamics Studies On Glass Formation Of Pd-Ni Alloys By Rapid Quenching, Sevgi̇ Özdemi̇r Kart, Mehmet Tomak, Mustafa Uludoğan, Tahi̇r Çağin

Turkish Journal of Physics

The rapid solidification of Pd-Ni alloys is studied with the constant-pressure and constant-temperature (TPN) and the constant-volume and constant-temperature (TVN) molecular dynamics technique to obtain an atomic description of glass formation in the alloy. Quantum Sutton-Chen potential for Pd-Ni binary system is applied in the simulations. We present some thermodynamic and structural results from simulations of such glasses over a range of compositions. The structural properties are analyzed by means of pair distribution function, volume, and enthalpy as a function of temperature and concentration at the cooling rates ranging from 5 K/ps to 0.05 K/ps to see whether the Pd-Ni …

Casimir Energies For Some Single Cavities, Haci Ahmedov, İsmai̇l Hakki Duru

Turkish Journal of Physics

Casimir energies are discussed for some cavities.

Hamilton-Jacobi Formulation Of Siegel Superparticle, N. I. Farahat, Hanaa A. Elegla

Turkish Journal of Physics

The Hamilton-Jacobi formalism of constrained systems is used to study Siegel superparticles moving in R^{4 mid 4} flat superspace. The equations of motion for a singular system are obtained as total differential equations in many variables. These equations of motion are in exact agreement with those obtained by Dirac's method.

Helicity Dependence Of The \Vec\Gamma\Vec N \To \Pi N Reaction Channels In The \Delta-Resonance Region, Eed M. Darwish, Mohamed A. El-Zohry

Turkish Journal of Physics

Based on a prior effective Lagrangian model on single pion photoproduction from the nucleon, successfully tested in total and differential cross sections, the helicity dependence from the interaction of circularly polarized photons and a longitudinally polarized nucleon target is studied in the energy range from \pi-threshold through the \Delta(1232)-resonance region. The doubly polarized total and differential cross section differences for parallel \sigma^{3/2} and antiparallel \sigma^{1/2} helicity states are predicted and compared with recent experimental data. We show that the results are sensitive to interferences among different contributions to the process and, thus, represent a complementary test of the theoretical model. …

Ibm-2 Calculations Of Selected Even-Even Ruthenium Nuclei, İlyas İnci̇, Nuretti̇n Türkan

Turkish Journal of Physics

In this study, we have employed the Interacting Boson Model-2 (IBM-2) to determine the most appropriate Hamiltonian for the study of ruthenium nuclei in the region A \cong 100. Using the best fit values of parameters to construct the Hamiltonian, we have estimated energy levels and multipole mixing ratios (\delta (E2/M1)) for some doubly-even Ru nuclei. The results are compared with previous experimental and theoretical data and it is observed that they are in good agreement.

Ibm-2 Calculations Of Selected Even-Even Palladium Nuclei, İlyas İnci̇, Nuretti̇n Türkan

Turkish Journal of Physics

In this study, we have employed the Interacting Boson Model-2 (IBM-2) to determine the most appropriate Hamiltonian for the study of palladium nuclei. Using the best fit values of parameters to construct the Hamiltonian, we have estimated energy levels and multipole mixing ratios (\delta (E2/M1)) for some doubly-even Pd nuclei. The results are compared with previous experimental and theoretical data and it is observed that they are in good agreement.

Band Gap Of Cubic Aln, Gan And Inn Compounds Under Pressure, S. Berrah, Hamza Abid, A. Boukortt, Mohamed Sehil

Turkish Journal of Physics

Numerical simulation based on FP-LAPW calculations is applied to study the lattice parameters, bulk modulus and band gap energy of zinc blende binaries AlN, GaN and InN under hydrostatic pressure. The results obtained are in a good agreement with experimental and theoretical values.

Comment On "Characterization Of In_4te_3 Single Crystals", M. Cankurtaran, H. Çeli̇k

Turkish Journal of Physics

No abstract provided.

Relationships Between Deflector Faults, Collapse Dolines And Collector Channel Formation: Some Examples From Slovenia, France Šušteršič

International Journal of Speleology

In some Slovenian caves collector channels gather sinking underground streams and redirect them for potentially long distances parallel to certain faults. The collector channels formed due to ongoing long-term collapse of cave roofs at the points where passages break through the faults, which function as a kind of screen and are termed deflector faults. The fault trends are marked by collapse within the caves, and by active collapse dolines at the surface.

Exchange Coupling And Contribution Of Induced Orbital Angular Momentum Of Low-Spin Fe^3+ Ions To Magnetic Anisotropy In Cyanide-Bridged Fe2m2 Molecular Magnets: Spin-Polarized Density-Functional Calculations, Stephen Holmes, Kyungwha Park

Chemistry & Biochemistry Faculty Works

Electronic structure and intramolecular exchange constants are calculated for three cyanide-bridged molecular magnets, [Tp⋆FeIII(CN)3MII(DMF)4]2(OTf)2∙2DMF (MII=Mn,Co,Ni) (abbreviated as Fe2Mn2, Fe2Co2, and Fe2Ni2) that have been recently synthesized, within a generalized-gradient approximation in spin-polarized density-functional theory (DFT). Here Tp⋆=[C3(CH3)2HN2]3BH, OTf=O3SCF3, and DMF=HCON(CH3)2. Due to strong ligand fields present in the [Tp⋆FeIII(CN)3]− units, the Fe3+ ions exhibit a low ground-state spin of S=1/2. Our calculations show that the metal ions in the Fe2Mn2 molecule interact antiferromagnetically via cyanide ligands, while those in the Fe2Co2 and Fe2Ni2 molecule interact ferromagnetically. The calculations also suggest that the smallest gaps between the highest occupied molecular orbital …

Residual Stress Distribution, Intermolecular Force, And Frictional Coefficient Maps In Diamond Films: Processing-Structure-Mechanical Property Relationship, Sanju Gupta, Oliver Williams, R. J. Patel, Eric W. Bohannan, P. W. May

Chemistry Faculty Research & Creative Works

Carbon in its various forms, specifically nanocrystalline diamond, may become a key material for the manufacturing of micro- and nano-electromechanical (M/NEMS) devices in the 21st Century. in order to utilize effectively these materials for M/NEMS applications, understanding of their microscopic structure and physical properties (mechanical, in particular) become indispensable. the micro- and nanocrystalline diamond films were grown using hot-filament and microwave chemical vapor deposition techniques involving novel CH4 / [TMB for boron doping and H2S for sulfur incorporation] in high hydrogen dilution chemistry. to investigate residual stress distribution and intermolecular forces at the nanoscale, the films were characterized using Raman …

Transition Rule Elicitation Methods For Urban Cellular Automata Models, Junfeng Jiao, Luc Boerboom

Research Collection College of Integrative Studies

In this chapter, transition rules used in urban CA models are reviewed and classified into two categories: transition potential rules and conflict resolution rules. Then, four widely used rule elicitation methods: Regression analysis, Artificial Neural network (ANN), Visual calibration, and Analytical Hierarchy Processing – Multi Criteria Evaluation (AHP-MCE) are discussed. Most of these methods are data driven methods and can be used to elicit the transition potential rules in the urban CA models. In the following, three possible rule elicitation methods: Interview, Document analysis, and Card sorting are explained and demonstrated. These three methods are driven by knowledge and can …

Segmental Dynamics Of Poly(Isopropyl Acrylate)-D7 On Silica, Piyawan Krisanangkura, Frank D. Blum

Chemistry Faculty Research & Creative Works

For a polymer film deposited on a surface, the strength of the surfacesegment interaction affects the mobility of polymer-chain segments. The selfconsistent field lattice model of Scheutjens and Fleer,1 based on mean-field lattice models of polymer at interfaces,2 has been used to describe the distribution of conformations of polymers on surfaces. Adsorbed-polymer segments may be classified as belonging to loops, trains or tails. There are different techniques used to study the molecular motion of the polymer including modulated differential scanning calorimetry (MDSC)3 and nuclear magnetic resonance (NMR).4,5 in this work, solid-state deuterium (2H) NMR was used to characterize the polymer …

Separation And Quantification Of N-Acetylcysteine-Amide (Naca) By Hplc With Fluorescence Detection, Wei Wu, Glenn Goldstein, Craig D. Adams, Richard H. Matthews, Nuran Ercal

Chemistry Faculty Research & Creative Works

N-acetyl-l-cysteine (NAC) is a well-known antioxidant that is capable of facilitating glutathione (GSH) biosynthesis and replenishing intracellular GSH under oxidatively challenging circumstances. N-acetyl-cysteine-amide (NACA), the amide form of NAC, is a newly designed and synthesized thiol-containing compound which is believed to be more lipophilic and permeable through cell membranes than NAC. The metabolic and antioxidant effects of these compounds in vitro and in vivo are under investigation. However, an analytical method that can separate and quantify both compounds simultaneously is not yet available, to the best of our knowledge. Because of their structural similarities, the two compounds are difficult to …

On Doubly Periodic Solutions Of Quasilinear Hyperbolic Equations Of The Fourth Order, T. Kiguradze, T. Smith

Publications

The problem on doubly periodic solutions is considered for a class of quasilinear hyperbolic equations. Effective sufficient conditions of solvability and unique solvability of this problem are established.

Lsuhsc Facilities Biweekly Update: January 2006, Lsuhsc Property And Facilities Management

LSUHSC Facilities Biweekly Updates: 2006

LSUHSC Facilities Biweekly Updates from January 13 and 27, 2006.

These updates describe damage and a timeline of repairs at the LSU Health Sciences Center - New Orleans campus due to Hurricane Katrina which made landfall August 29, 2005.