Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

2000

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 2401 - 2430 of 2640

Full-Text Articles in Physical Sciences and Mathematics

Consistency Of The Born Approximation For Aharonov-Bohm Scattering With Massless Spin-1/2 Particles, Müge Boz, Namik Kemal Pak Jan 2000

Consistency Of The Born Approximation For Aharonov-Bohm Scattering With Massless Spin-1/2 Particles, Müge Boz, Namik Kemal Pak

Turkish Journal of Physics

The second order contribution for the relativistic scattering of massless spin-$\frac{1}{2}$ particles from an infinitely long solenoid, in the context of covariant perturbation theory, is calculated and shown to vanish. Thus, Born approximation is consistent for this case as well.

Go to article

Molecular Dynamics Simulations Of Super Heated Ni_4 Cluster, M. Haluk Güven Jan 2000

Molecular Dynamics Simulations Of Super Heated Ni_4 Cluster, M. Haluk Güven

Turkish Journal of Physics

The fragmentation mechanism of the super heated Ni4 cluster is studied by employing the microcanonical molecular dynamics simulations and an empirical model potential. Ni$_{4}$ cluster is heated up above the bulk Ni evaporation point temperature and then classical trajectory analysis as well as RRK theory are used to calculate survival probability, evaporation rate, average kinetic energy release and dissociation energy.

Go to article

The Magnetic Super-Exchange Coupling In Copper(Ii) Acetate Monohydrate And A Redetermination Of The Crystal Structure, Ayhan Elmali Jan 2000

The Magnetic Super-Exchange Coupling In Copper(Ii) Acetate Monohydrate And A Redetermination Of The Crystal Structure, Ayhan Elmali

Turkish Journal of Physics

The magnetic properties and redetermination of crystal structure of copper(II) acetate monohydrate have been studied. The copper(II) centers are separated by 2.617(1) \AA \ and antiferromagnetically coupled (-2J = 292.2 cm$^{-1}$), which follows from temperature-dependent magnetic susceptibility measurements in the temperature range 4.2 to 300 K. The magnetic moment at 300 K is about 2.1 Bohr magnetons while 0.1 Bohr magnetons at 4.2 K. The magnetic susceptibility is at a maximum near 250 K and decreases rapidly as the temperature is lowered to liquid helium temperature.

Go to article

Antiferromagnetic Transition In \Alpha-Mn-Fe System, R. K. Nkum, F. Boakye Jan 2000

Antiferromagnetic Transition In \Alpha-Mn-Fe System, R. K. Nkum, F. Boakye

Turkish Journal of Physics

Antiferromagnetic transition in $\alpha$-Mn-Fe alloys has been studied using resistivity-temperature measurements from 300 to 1.5 K. The results indicate that the transition temperature $T_N$ of the samples studied increases with increasing Fe concentration. This suggests that the N\'{e}el temperature is affected by Fe. Also, Fe plays a significant role in the local disorder on the magnetic moment of the ions in the complex manganese structure.

Go to article

Determination Of Optical Constant Of Materials By Two Different Methods: An Application To Single Crystals Si, Hazi̇ret Durmuş, Haluk Şafak, Haldun Karabiyik Jan 2000

Determination Of Optical Constant Of Materials By Two Different Methods: An Application To Single Crystals Si, Hazi̇ret Durmuş, Haluk Şafak, Haldun Karabiyik

Turkish Journal of Physics

The normal reflectance of single crystal Si was measured at 0.5 ­5.6 eV range by unpolarized light. Optical parameters of Si were determined from this reflectance data by using two different methods: oscillator fit procedure and Kramers-Kronig analysis. The refractive index, extinction coefficient and the real and imaginary parts of complex dielectric constant obtained by these two methods were compared. A good agreement was found between two methods. Furthermore, the optical parameters so obtained seem to be in a satisfactory agreement with the literature.

Go to article

Crystallographic Analysis Of Martensitic Transformation In Cusn Alloy, Ekrem Artunç, Seyfetti̇n Çakmak, Seval Çakmak Jan 2000

Crystallographic Analysis Of Martensitic Transformation In Cusn Alloy, Ekrem Artunç, Seyfetti̇n Çakmak, Seval Çakmak

Turkish Journal of Physics

In this study, the Kajiwara model has been applied to Cu-14.8at.\%Sn alloy with good agreement with experimental results. For this alloy, the austenite phase has a body centered cubic (bcc) lattice and the martensite phase has a monoclinic 9R superlattice. Using the lattice parameters of both phases, the calculated habit plane indices, magnitude of the lattice invariant shear and orientation relationships, have been compared with the observed results for this alloy.

Go to article

Linac-Ring Type \Phi Factory Of Basic And Applied Research, A. Kenan Çi̇ftçi̇, Osman Gürkan, Turan Olgar, Erdal Recepoğlu, Saleh Sultansoy, Ömer Yavaş, Meti̇n Yilmaz Jan 2000

Linac-Ring Type \Phi Factory Of Basic And Applied Research, A. Kenan Çi̇ftçi̇, Osman Gürkan, Turan Olgar, Erdal Recepoğlu, Saleh Sultansoy, Ömer Yavaş, Meti̇n Yilmaz

Turkish Journal of Physics

In this paper, main parameters for linac-ring type collider designed for producing $\phi $ particles copiously are estimated and the potential of this machine in particle physics research is investigated. Moreover, parameters for free electron laser and synchrotron radiation obtained from electron linac and positron ring, respectively, are determined and applications of these radiations are summarized.

Go to article

A Product Operator Formalism Of 3d J-Resolved Nmr Spectroscopy For Is_Nk_M(I = 1/2, S = 1/2, K = 1/2) Spin System, Özden Tezel, Azmi̇ Gençten Jan 2000

A Product Operator Formalism Of 3d J-Resolved Nmr Spectroscopy For Is_Nk_M(I = 1/2, S = 1/2, K = 1/2) Spin System, Özden Tezel, Azmi̇ Gençten

Turkish Journal of Physics

Product operator formalism is widely used for analytical description of multiple-pulse NMR experiments for weakly coupled spin systems. 3D J-resolved NMR spectroscopy is widely used in order to resolve the chemical shift along one axis and spin-spin coupling parameters along the two other axis. In this study, product operator theory is used for analytical description of heteronuclear 3D J-resolved NMR spectroscopy for the \( IS_nK_m (I=1/2, S=1/2, K=1/2; n=1,2, m=1,2,3) \) spin system.

Go to article

Mass-Radius Relations For Helium White Dwarfs, Ri̇kkat Ci̇velek, Ni̇lgün Kiziloğlu Jan 2000

Mass-Radius Relations For Helium White Dwarfs, Ri̇kkat Ci̇velek, Ni̇lgün Kiziloğlu

Turkish Journal of Physics

We studied the static mass-radius relation of white dwarf stars with masses greater than 0.45 $M_\odot$. We assumed pure degenerate helium interiors at a finite temperature with luminosity-mass ratio due to neutrino energy loss. We compared the obtained M-R relation with those of other writers.

Go to article

An Extended Adiabatic Approach For Nuclear Reactions, Mustafa Yilmaz, Bülent Gönül Jan 2000

An Extended Adiabatic Approach For Nuclear Reactions, Mustafa Yilmaz, Bülent Gönül

Turkish Journal of Physics

In this letter, an alternative approximation is developed for the treatment of breakup process in nuclear reactions, which presents a way of evaluating non-adiabatic corrections to the adiabatic model three-body wavefunction by introducing a more consistent prescription for the continuum n-p center of mass energy. Although the present formalism goes beyond the quasi-adiabatic approach, due to the use of exact continuum channel energies, its application to deuteron involving reactions at medium energies shows that such an approach can not be used in its present form. A possible reason behind this failure is discussed.

Go to article

Microhardness Creep In Single Crystals Of Tin-Chalcogenides, S. M. Vyas, C. F. Desai, R. C. Shah, G. R. Pandya Jan 2000

Microhardness Creep In Single Crystals Of Tin-Chalcogenides, S. M. Vyas, C. F. Desai, R. C. Shah, G. R. Pandya

Turkish Journal of Physics

SnSe and SnS have been grown by Bridgman- Stockbarger method. Loading time as a function of vickers microhardness has been measured at different temperatures in the range 303 K to 388K. Al measurement of hardness have been carried out on the cleavage planes. The activation energy for creep has been evaluated to be 2.92 and 1.75 K Cal/mole, respectively, for SnSe and SnS crystals.

Go to article

The Growth Of P-Type A^{Iii} B^{Iii} C_2^{V I} Single Crystals, Beki̇r Gürbulak, Cevdet Coşkun, Seydi̇ Doğan, Aytunç Ateş, Yahya Kemal Yoğurtçu Jan 2000

The Growth Of P-Type A^{Iii} B^{Iii} C_2^{V I} Single Crystals, Beki̇r Gürbulak, Cevdet Coşkun, Seydi̇ Doğan, Aytunç Ateş, Yahya Kemal Yoğurtçu

Turkish Journal of Physics

$A^{III}B^{III}C_2^{VI}$ single crystals were grown by the modified Bridgman-Stockbarger method, a procedure similar to direct freezing in our crystal growth laboratory. $A^{III}B^{III}C_2^{VI}$ compounds are collected into two groups (III. group: TI, Ga, In and VI. group: Se, S, Te): 1. TlGaSe$_2$, TlGaS$_2$ and TlInS$_2$ have layer structure. 2. TlInSe$_2$, TlInTe$_2$ and TlGaTe$_2$ have chained structure. The main reasons such crystals grown with this method is similar to the direct freezing method because 1) quality of crystals is the same as crystals grown by other methods, and 2) growth time of crystals is shorter by about 5-10 days. None of the …

Go to article

Doping Of High-Temperature Superconductors, Sh. Meretliev, K. B. Sadykov, A. Berkeliev Jan 2000

Doping Of High-Temperature Superconductors, Sh. Meretliev, K. B. Sadykov, A. Berkeliev

Turkish Journal of Physics

High-temperature superconducting ceramics systems YBaCuO and BiSrCaCuO, both doped by Pb, Sb, Li, K, Na and non-doped, have been produced by the method of solid phase reaction synthesis. The principle of controlled valency by Vervey has been used to characterize high-temperature superconductors. High-temperature superconducting ceramics have been obtained with properties stable in time by single-purpose doping.

Go to article

The Absorption Properties Of P-Type Tlin_X Ga_{(1-X)} Se_2 And Tlgase_2, Beki̇r Gürbulak, Muhammet Yildirim, Aytunç Ateş, Sebahatti̇n Tüzemen, Yahya Kemal Yoğurtçu Jan 2000

The Absorption Properties Of P-Type Tlin_X Ga_{(1-X)} Se_2 And Tlgase_2, Beki̇r Gürbulak, Muhammet Yildirim, Aytunç Ateş, Sebahatti̇n Tüzemen, Yahya Kemal Yoğurtçu

Turkish Journal of Physics

$p-TlGaSe_2$, $p-TlIn_{0.3}Ga_{0.7}Se_2$ and $p-TlIn_{0.5}Ga_{0.5}Se_2$ single crystals were grown by the modified Bridgman-Stockbarger method in our crystal growth laboratory. The absorption measurements were carried out on $p-TlIn_xGa_{(1-x)}Se_2$ samples in temperature range 10-300 K in steps of 10 K. The binding energies of $p-TlGaSe_2$, $p-TlIn_{0.3}Ga_{0.7}Se_2$ and $p-TlIn_{0.5} Ga_{0.5}$ $Se_2$ were obtained as \\ 35.0 meV, 16.5 meV and 14.5 meV, respectively. THe direct band gaps were calculated as 2.244 eV, 2.195 eV, 2.164 eV in $p-TlGaSe_2$, 2.158 eV, 2.131 eV, 2.098 eV in $p-TlIn_{0.3}Ga_{0.7}Se_2$, and 2.107 eV, 2.075 eV, 2.019 eV in $p-TlIn_{0.5}Ga_{0.5}Se_2$ respectively, at sample temperatures of 10 K, 140 K …

Go to article

Chemically Synthesised Cd_{(1-X)}Zn_Xse Thin Films: Spectro-Structural And Microscopic Studies, D. S. Sutrave, G. S. Shahane, V. B. Patil, L. P. Deshmukh Jan 2000

Chemically Synthesised Cd_{(1-X)}Zn_Xse Thin Films: Spectro-Structural And Microscopic Studies, D. S. Sutrave, G. S. Shahane, V. B. Patil, L. P. Deshmukh

Turkish Journal of Physics

This paper presents information pertaining to the chemo-mechanical synthesis of (Cd,Zn) Se thin films with a variable composition which has been brought about with the objective to study deposition history and growth kinetics, as well as structural changes and the optical properties. The effect of various process parameters, such as deposition time and temperature, concentration of species, speed of the substrate rotation, pH etc., on the growth and quality of the films is studied experimentally. At first sight, mechanistic interpretation of the reaction mechanism is given based on the influence of the process parameters on the film growth and the …

Go to article

A Local-Pair Mechanism For High-Temperature Superconductivity At The Di- And Trivalent Sites, John A. Wilson, Ali̇ İhsan Demi̇rel Jan 2000

A Local-Pair Mechanism For High-Temperature Superconductivity At The Di- And Trivalent Sites, John A. Wilson, Ali̇ İhsan Demi̇rel

Turkish Journal of Physics

The \( p/d \) hybridization that primarily characterizes copper leads to local moments, lacking of the pair-breaking variety, both at di- and trivalent sites. Support for the negative-U model is extracted from the author's earlier work on the metal-insulator transition. A more magnetically oriented model, like the resonant valence band model which we have recently associated with our observations in d1 TiOCl etc., does not really seem suited to the geometry and electronic conditions in the copper oxides present. However it is suggested that TiB$_2$, La$_3$S$_4$ and the Chevrel phases might be open to treatment by such a model. Comment …

Go to article

Switching Process In A Surface-Stabilized Ferroelectric Liquid Crystal Film, Ridvan Karapinar Jan 2000

Switching Process In A Surface-Stabilized Ferroelectric Liquid Crystal Film, Ridvan Karapinar

Turkish Journal of Physics

In this paper we first discuss the operating principle of a ferroelectric liquid crystal film in the surface stabilized configuration, and then examine the switching characteristics using optical measurements performed with a polarizing microscope.

Go to article

Effects Of Disorder On The Drag Rate In Double Quantum-Wire Systems, B. Tanatar Jan 2000

Effects Of Disorder On The Drag Rate In Double Quantum-Wire Systems, B. Tanatar

Turkish Journal of Physics

We study the Coulomb drag rate for electrons in a double quantum-wire structure in the presence of disorder. We use the particle number-conserving relaxation-time approximation to phenomenologically broaden the response functions entering the drag rate expression to account for the disorder effects. In contrast to the usual low-temperature regime investigated by various researchers, we focus our attention on the high-temperature drag rate to which plasmon modes are known to make substantial contribution. The full wave vector and frequency dependent random-phase approximation (RPA) at finite temperature and disorder strength is employed to describe the effective interlayer Coulomb interaction. The interplay between …

Go to article

An Architectural Framework For Performance Analysis: Supporting The Design, Configuration, And Control Of Dis /Hla Simulations, David B. Cavitt Jan 2000

An Architectural Framework For Performance Analysis: Supporting The Design, Configuration, And Control Of Dis /Hla Simulations, David B. Cavitt

Computer Science Theses & Dissertations

Technology advances are providing greater capabilities for most distributed computing environments. However, the advances in capabilities are paralleled by progressively increasing amounts of system complexity. In many instances, this complexity can lead to a lack of understanding regarding bottlenecks in run-time performance of distributed applications. This is especially true in the domain of distributed simulations where a myriad of enabling technologies are used as building blocks to provide large-scale, geographically disperse, dynamic virtual worlds. Persons responsible for the design, configuration, and control of distributed simulations need to understand the impact of decisions made regarding the allocation and use of the …

Go to article

An Examination Of A Multidimensional Model Of Customer Satisfaction With Internet Purchasing, Kathleen Vanscoyoc Jan 2000

An Examination Of A Multidimensional Model Of Customer Satisfaction With Internet Purchasing, Kathleen Vanscoyoc

Theses and Dissertations in Business Administration

The World Wide Web and Internet have transformed the competitive business environment and altered the customer-firm relationship by creating a new retailing format and service enterprise. It is rapidly growing as a competitive distribution medium in which customer satisfaction will be a major success factor in the development and maintenance of this new retailing format. Despite its growing importance as a new shopping medium, little empirical research has been conducted that examines the relationship between Internet shopping, customer satisfaction, company image, and future online purchasing. Research is needed to develop theoretical models that will systematically explain and predict behavior related …

Go to article

Day Of The Week Effect In The Kuala Lumpur Stock Exchange, 1994-1998, Santhi Arasan Jan 2000

Day Of The Week Effect In The Kuala Lumpur Stock Exchange, 1994-1998, Santhi Arasan

Student Works (2000-2009)

This paper investigates whether the day of the week effect anomaly exists in the Kuala Lumpur Stock Exchange (KLSE) over a period of time from 1994 to 1998 using the Exchange Main Board All-Share Index or the EMAS Index, which incorporates all Main Board Companies. The analysis of the day of the week effect during the study period is further explored in relation to firm size and economic conditions. In relation to firm size, this paper investigates whether the day of the week effect is persistent for both large and small firms by comparing the daily mean returns of the …

Go to article

E-Commerce : Web Page Standards And Consumer Confidence, Natarajan @ Kumar Nc Krishnan Jan 2000

E-Commerce : Web Page Standards And Consumer Confidence, Natarajan @ Kumar Nc Krishnan

Student Works (2000-2009)

This thesis involves around the generation of a set of recommendations for web page design that could be possibly used by authorities or auditing firms to audit and approve commercial web pages that comply to the standards. The recommendations shall cover what information consumers would like to see on commercial web pages. The contents of a web page are critically important in Electronic Commerce as it is the only interface between consumers and the merchant. Web Page Approval shall be a preferred way of identifying a web page to do online business by potential consumers. Consumer shall have increased confidence …

Go to article

Optimisation Of Transverse Arc Array Laser, Albert Kok Foo Ng Jan 2000

Optimisation Of Transverse Arc Array Laser, Albert Kok Foo Ng

Student Works (2000-2009)

A novel discharge scheme is proposed for the pumping of short wavelen,gth lasers. This scheme had been tested to produce fast current pulse and a 5 kA current in 60 nsec is obtained. Lasing action has been observed by using nitrogen gas. The laser line is 337 nm from the strong transitions of nitrogen molecules. The new discharge scheme is based on the concept of an arc array amplifier. It essentially consists of 48 pairs of electrodes which are lined up to form an array of arc discharge. Its electrical circuitry allows each pair of the electrodes to be decoupled …

Go to article

On Strongly N-Regular And Strongly Regular Rings, Huey Voon Chen Jan 2000

On Strongly N-Regular And Strongly Regular Rings, Huey Voon Chen

Student Works (2000-2009)

Let R be an associative ring with identity 1 (not equal to) 0. An element x E R is said to be right (or left) regular if there exists yin R such that x² y = x (or y.x² = x). If x is both left and right regular, then it is said to be strongly regular. The ring R is said to be strongly regular if every element of R is strongly regular. We say that x is a left -π-regular element if there exist an integer n > 0 and an element y E R such that yx n+1 …

Go to article

Understanding Of The Limit Of Functions Among College Students, Logesh K. Sivapakianathan Jan 2000

Understanding Of The Limit Of Functions Among College Students, Logesh K. Sivapakianathan

Student Works (2000-2009)

This study explored concept images and concept definitions of college students on limits of functions. Their views concerning the attainability of the limit and the extent to which they understood the stand taken by the formal view on this matter were also probed on. The sample comprised 10 students who had completed the Calculus and Analytic Geometry 1 course in the School of American University Studies at a private college in the Klang Valley. A questionnaire on beliefs about limits was administered to them and 4 students were then selected for a task-based interview on the attainability of the limit. …

Go to article

Infrared Spectoscopy And Electrical Conductivity Of Copper(Ii) 4-Aminobenzoate And Iondine-Doped Copper(Ii) 4-Aminobenzoate, Chang Fu Dee Jan 2000

Infrared Spectoscopy And Electrical Conductivity Of Copper(Ii) 4-Aminobenzoate And Iondine-Doped Copper(Ii) 4-Aminobenzoate, Chang Fu Dee

Student Works (2000-2009)

Copper(II) 4-aminobenzoate (CAB), prepared from copper(II) acetate monohydrate and 4-aminobenzoic acid, was a dark green powder. Fourier Transfonn lnfrared (FTIR) spectrum of CAB, recorded as KBr disc, indicated the presence of all bonds and functional groups expected of it, and the absence of hydrogen bonding. Its conductivity at room temperature was 4.2 x 10^-11 Scm^·1. The value increased as temperature decreased indicating metallic behaviour. Density of states at Fenni level, hopping distance, hopping energy and density of charge carriers calculated based on Mon's Variable Range Hopping model (VRH) are 2.65x 10^-22 (eV)^-1 cm^-3, 7.47 x 10^-8 cm, 0.02 eV and …

Go to article

Investigations Of Transverse Arc Array Laser Action In Nitrogen Gas, Kee Siang Goh Jan 2000

Investigations Of Transverse Arc Array Laser Action In Nitrogen Gas, Kee Siang Goh

Student Works (2000-2009)

In almost all pulsed gas lasers, transverse electrical discharge is employed in the excitation of the atoms or molecules. These lasers normally employ discharge across a pair of common electrodes to provide large volume and uniform glow discharge. The scaling of output power in such lasers is obtained by increasing the volume of the discharge and also the pressure of the discharge gas. For this reason. the energy coupled into the discharge channel is kept low enough to avoid arcing. Under these circumstances, the electron temperature of such uniform glow discharge is not sufficient to produce excitation of VUV or …

Go to article

Investigations On The Conductivity Of Organotin-Doped Polyethyleneoxide Polymer System, Lekshmi Sarojiniamma Jan 2000

Investigations On The Conductivity Of Organotin-Doped Polyethyleneoxide Polymer System, Lekshmi Sarojiniamma

Student Works (2000-2009)

Poly(ethylene oxide) (PEO) has been doped with selected organotin compounds. The organotin dopants used were triphenyltin thiocyanate (Ph3SnSCN) and tetramethylammonium dichlorotriphenylstannate [Ph3SnClr[Me4N)•. Tin incorporation in the polymers was established by several physical techniques. The infrared spectroscopic analysis of the Pb3SnSCN - doped electrolyte film showed bands at 2080-2050 cm.·' which are also given by pure Ph3SnSCN. Different concentrations of organotin doped electrolytes were prepared and conductivity studies on these were perfonned using impedance spectroscopy. From the measurements it was found that the best conductivity of 7.6xJ0.g Siem was obtained for the composition with PEO :dopant ratio of90:10 at room temperature. …

Go to article

Isolation And Identification Of Sterols In Palm Oil And Their Analysis By Gc Adn Gc-Ms, Ai Chen Han Jan 2000

Isolation And Identification Of Sterols In Palm Oil And Their Analysis By Gc Adn Gc-Ms, Ai Chen Han

Student Works (2000-2009)

The unsaponifiablc matters were separated from crude palm oil, crude palm kernel oil, and crude palm fibre oil. The sterol fractions were isolated by preparative thin layer chromatography and were then analysed by gas chromatography and combined gas chromatography-mass spectrometry. Qualitative separations of sterols are illustrated. Tables are presented showing the sterol composition determined in the oi ls, values obtained for individual contents are in broad agreement with other published results There were no major differences between crude palm oil, crude palm kernel oil and crude palm fibre oil with respect to their sterols oomposition. P-sitosterol was found as the …

Go to article

Method Development And Validation For Drug Analysis By Hplc Gc-Ms, Yann Jen Goh Jan 2000

Method Development And Validation For Drug Analysis By Hplc Gc-Ms, Yann Jen Goh

Student Works (2000-2009)

Enalapril and its metabolite Enalaprilat were determined by gas chromatography - mass spectrometry (GC - MS) and high - performance liquid chromatography (HPLC). For HPLC, the detection limit of enalapril and enalaprilat was 10n g/ml in methanol, whereas for the GC - MS, the detection limit was 6.25ng/ml in plasma. These methods were compared and GC - MS was selected for routine analysis. Enalapril and Enalaprilat in plasma were extracted and cleaned up by using Sep - Pak C 18. Enalapril and Enalaprilat were detected after reaction with diazomethane and were identified by gas chromatography - mass spectrometry as methyl …

Go to article

First Prev Next Last