Nuclear shapes and interaction potentials of two colliding208Pb nuclei at finite temperature

The effect of nuclear and Coulomb interactions on the shapes of two colliding²⁰⁸Pb nuclei at finite temperature is investigated. The complex potential energy density derived by Faessler and collaborators and the kinetic energy density and entropy density for two Fermi spheres at finite temperature are used to calculate the free energy of the²⁰⁸Pb +²⁰⁸Pb system in the energy density formalism. Shell corrections are added to the free energy in the framework of the Strutinsky method. The total free energy is minimized with respect to the quadrupole deformation and the diffuseness to determine the density distribution of²⁰⁸Pb nucleus at certain distanceR and temperatureT assuming the deformed Woods-Saxon shape for each nucleus. It is found that the nucleus acquires larger deformation and diffuseness as the temperature increases. The interaction potential between two²⁰⁸Pb nuclei is calculated from the minimized free energy. The total (nuclear + Coulomb) potential is found to decrease with increasing temperature, whereas the real part of the nuclear potential becomes more repulsive as the temperature increases.     

Milling time and BPR dependence on permeability and losses of Ni0.5Zn0.5Fe2O4 synthesized via mechanical alloying process

Ni_0.5Zn_0.5Fe₂O₄ has been synthesized using mechanical alloying method with two variables (milling time and ball-to-powder weight ratio (BPR)) were varied in order to study its effect on the magnetic properties of the material. The effects of these two variables were studied using XRD, SEM, TEM and later by impedance analyzer with the frequency range from 1 MHz to 1.8 GHz. The results obtained however show that there are no significant trends to relate the milling time and BPR with the permeability and losses of the material studied. After being sintered at 1150 °C, all the effects of alloying process seem to diminish.     

Degradation of phenol using a combination of ultrasonic and UV irradiations at pilot scale operation

In the present work, combination of ultraviolet (UV) irradiations (using 8 W UV tube) with ultrasonic (US) irradiations (rated power 1 kW and frequency of 25 kHz) has been investigated for the degradation of phenol at pilot scale of operation. Different modes of operation viz. UV alone, US alone, UV/US, UV/TiO₂ (photocatalysis), UV/H₂O₂, UV/NaCl, UV/US/TiO₂ (sonophotocatalysis) and H₂O₂ assisted sonophotocatalysis have been investigated with an objective of maximizing the extent of phenol degradation. Effect of presence of hydrogen peroxide and sodium chloride at a concentration of 10 g/l and TiO₂ over a range of 0.5–2.5 g/l has been investigated. It has been observed that 2.0 g/l of TiO₂ is the optimum concentration, beyond which a decrease in the extent of degradation is observed. Maximum extent of degradation of phenol was 37.75% for H₂O₂ assisted photosonocatalysis at pH of 2. The present work is first of its kind to report the use of combined ultrasonic and UV irradiations at pilot scale operation and obtained results should induce some degree of certainty in proposed industrial applications of sonochemical reactors for wastewater treatment.     

The Two-Nucleon Stripping Process with Skyrme Type Potential

Theory of two-nucleon stripping reactions is reconsidered. The nucleon-nucleon interactions are taken as Skyrme type potentials. Differential cross-sections for two-nucleon stripping reactions are calculated using DWBA approximation with different Skyrme type potentials of different parameters. The angular distributions for different two-nucleon stripping reactions (t, p) with incident triton on the different targets of ³¹P, ⁴⁰Ca, ⁹⁶Zr, ¹¹⁸Sn and ²⁰⁶Pb are calculated giving good agreement with the experimental data. Better values are extracted for the spectroscopic factors.     

A scale model investigation of sound reflection from building façades

A simple model for predicting the sound reflected from a building façade is developed based upon the assumption that the scattering coefficient is small. This model is then used as the basis of an experimental attempt to measure the scattering properties of scale model façades featuring a similar degree of surface irregularity to that found on real buildings. A series of measurements made on a simple scale model are described and the effect of a non-uniform distribution of façade scattering is examined. The measured value of the scattering coefficient is found to be small and not very sensitive to the degree of surface irregularity. A progression of energy from a specular reflection field to a diffuse reflection field for successive orders of reflections is observed. It is suggested that the dominant mechanism of sound propagation for higher order reflections is via random scattering and that the development of propagation models based upon purely random scattering is a valid approach.     

Raman spectroscopy with an integrated arrayed-waveguide grating

An integrated arrayed-waveguide grating fabricated in silicon-oxynitride technology is applied to Raman spectroscopy. After its validation by reproducing the well-known spectrum of cyclohexane, polarized Raman spectra are measured of extracted human teeth containing localized initial carious lesions. Excellent agreement is obtained between the spectra of healthy and carious tooth enamel measured with our integrated device and spectra recorded using a conventional Raman spectrometer. Our results represent a step toward the realization of compact, hand-held, integrated spectrometers, e.g. for the detection of dental caries at an early stage.     

A Numerical Calculation for Electron Impact Excitation of Copper

The scattering of electrons by atomic copper has been studied using Born approximation and the concept of the generalized oscillator strength (GOS). Differential and total cross-sections for the excitation of the 3d¹⁰ 4p² P state are calculated at incident energies of 100 eV and are compared with other available experimental and theoretical data. The agreement between our calculation for the differential cross-section and the available experimental results is fairly good at the forward angles, while the agreement at large angles is poor. The calculated total cross-sections are compared with the experimental data and those predicted by several theories. It is found that our calculation for the total cross-sections are in a good agreement with the close coupling calculation of Msezane and Henry (1986a, Physical Review A 33, 1631) for incident energies greater than 20 eV. The integrated cross-section measurements of Ismail and Teubner (1995, Journal of Physics B: Atomic, Molecular and Optical Physics 28, 4164) are in good agreement with the present calculation.