Direct fragmentation of quarkonia including Fermi motionusing light-cone wave function

We investigate the effect of Fermi motion on the direct fragmentation of the and states employing a light-cone wave function. Consistent with such a wave function we set up the kinematics of a heavy quark fragmenting into quarkonia such that the Fermi motion of the constituents splits into a longitudinal as well as a transverse direction and thus calculate the fragmentation functions for these states. In the framework of our investigation, we estimate that the fragmentation probabilities of and may increase at least up to 14 percent when including this degree of freedom. Received: 11 May 2004, Revised: 23 April 2005, Published online: 31 May 2005 PACS: 13.87.Fh, 13.85.Ni, 12.38.Bx, 12.39.Hg An erratum to this article is available at .     

Numerical prediction of turbulent flow structure generated by a synthetic cross‐jet into a turbulent boundary layer

A detailed numerical study using large‐eddy simulation (LES) and unsteady Reynolds‐averaged Navier–Stokes (URANS) was undertaken to investigate physical processes that are engendered in the injection of a circular synthetic (zero‐net mass flux) jet in a zero pressure gradient turbulent boundary layer. A complementary study was carried out and was verified by comparisons with the available experimental data that were obtained at corresponding conditions with the aim of achieving an improved understanding of fluid dynamics of the studied processes. The computations were conducted by OpenFOAM C++, and the physical realism of the incoming turbulent boundary layer was secured by employing random field generation algorithm. The cavity was computed with a sinusoidal transpiration boundary condition on its floor. The results from URANS computation and LES were compared and described qualitatively and quantitatively. There is a particular interest for acquiring the turbulent structures from the present numerical data. The numerical methods can capture vortical structures including a hairpin (primary) vortex and secondary structures. However, the present computations confirmed that URANS and LES are capable of predicting current flow field with a more detailed structure presented by LES data as expected. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and Evaluation of Technical Properties of Novel Cationic Mono‐s‐chloro Triazinyl (MCT) Reactive Dyes on Cotton

Two novel cationic mono‐s‐chloro triazinyl (MCT) reactive dyes together with their analogues were synthesized via reacting an N,N‐dimethyl dodecylamine with p‐nitrobenzyl bromide. The resultant was reduced using stannous chloride and hydrochloric acid to produce the primary amine. The quaternary ammonium salt containing primary amine was then diazotized and coupled to H‐acid/J‐acid reacted with cyanuric chloride and sulfanilic acid. The analogue dyes were prepared via the same route without quaternary ammonium salt making stage. The dyes were characterized using FTIR, ¹H NMR, UV‐Vis spectroscopy and elemental analysis. The substantivity, exhaustion and fixation of the dyes were investigated on cotton fabric. It was found that these functional dyes could be effectively introduced to cotton for achieving simultaneous coloration and functional finishing effects. All the dyed fabrics exhibited softening efficacy. The washing and light fastness of the dyed samples were further studied.     

Characterisation of alkyl amines at the water/air surface with the drop and bubble profile analysis tensiometry

Pendant drop and buoyant bubble methods have been used to study the surface characteristics of alkyl amines at the water/air surface. The investigated alkyl amines, triethylamine and octylamine, showed unusual changes in the surface tension as a function of time: an initially steep drop and a subsequent steady increase in the surface tension until a value close to the one of the pure water/air system was observed. This phenomenon is explained by the evaporation of the alkyl amines, for which several sets of experiments have been conducted with the pendant drop and buoyant bubble methods. Using an appropriate experimental protocol, the equilibrium adsorption behaviour of the two amines can be quantitatively measured.     

Diffraction patterns and nonlinear optical properties of gold nanoparticles

Stable gold nanoparticles have been prepared by using soluble starch as both the reducing and stabilizing agents; this reaction was carried out at 40 °C for 5 h. The obtained gold nanoparticles were characterized by UV–Vis absorption spectroscopy, transmission electron microscopy (TEM) and z-scan technique. The size of these nanoparticles was found to be in the range of 12–22 nm as analyzed using transmission electron micrographs. The optical properties of gold nanoparticles have been measured showing the surface plasmon resonance. The second-order nonlinear optical (NLO) properties were investigated by using a continuous-wave (CW) He–Ne laser beam with a wavelength of 632.8 nm at three different incident intensities by means of single beam techniques. The nonlinear refractive indices of gold nanoparticles were obtained from close aperture z-scan in order of 10^?7 cm²/W. Then, they were compared with diffraction patterns observed in far-field. The nonlinear absorption of these nanoparticles was obtained from open aperture z-scan technique. The values of nonlinear absorption coefficient are obtained in order of 10^?1 cm/W.     

Synthesis and nonlinear optical characterization of SnO2 quantum dots

The present paper demonstrates the preparation and characterization of SnO₂ semiconductor quantum dots. Extremely small ∼1.1 and ∼1.4 nm SnO₂ samples were prepared by microwave assisted technique with a frequency of 2450 MHz. Based on XRD analysis, the phase, crystal structure and purity of the SnO₂ samples are determined. UV-vis measurements showed that, for the both size of SnO₂ samples, excitonic peaks are obtained at ∼238 and ∼245 nm corresponding to ∼1.1 nm (sample 1) and ∼1.4 nm (sample 2) sizes, respectively. STM analysis showed that, the quantum dots are spherical shaped and highly monodispersed. At first, the linear absorption coefficients for two different sizes of SnO₂ quantum dots were measured by employing a CW He-Ne laser at 632.8 nm and were obtained about 1.385 and 4.175 cm⁻¹, respectively. Furthermore, the nonlinear refractive index, n₂, and nonlinear absorption coefficient, β, were measured using close and open aperture Z-scan respectively using the same laser. As quantum dots have strong absorption coefficient to obtain purely effective n₂, we divided the closed aperture transmittance by the corresponding open aperture in the same incident beam intensity. The nonlinear refraction indices of these quantum dots were measured in order of 10⁻⁷ (cm²/W) with negative sign and the nonlinear absorption coefficients were obtained for both in order of 10⁻³ (cm/W) with positive sign.     

Measurement base change for localization encoded dual rail photonic quantum computing

We study behavior of number states in systems of coupled modes. Using an auxiliary mode and linear transformations, we propose a simple method for measuring on orthogonal bases other than 0 and 1 in the case of dual rail photonic computing which may act as a simple filter too. Using two auxiliary modes it is shown that an equivalent polarizing beam splitter can be realized for dual rail encoding. Simple structures based on coupled waveguides are presented for these purposes.