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Volume2, Issue2


ARTICLES

Page 35PDF: X-Ray and Infrared Studies for NiSiXFe2-xO4 Ferrites

D. M. Hemeda, M. Z. Said

Abstract: A spinel ferrite of the system NiSixFe2-xO4 with (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) were studied via IR, X-ray spectra and cation distribution. The X-ray pattern confirmed the spinel cubic structure of all Si contents. The lattice parameters estimated as a function of Si contents indicated a slight decrease of lattice parameter up to 0.2. The grain size increases with increasing Si content up to 0.3 and then decreases for higher Si content. The jump length of electrons decreased with Si concentration up to 0.2. Four absorption bands were observed in infrared spectra in the range between 1000 and 200 cm-1. These bands are assigned to Fe3+ and Si4+ at the A- and B-sites. The two high frequency bands in the range 580-555 and 450-400 cm-1 is assigned to υ1 tetrahedral (A-site) and υ2 octahedral (B-site).


Page 44PDF: Physical Significances of Fifth-Order Nonlinearity for Pulse Dynamics in Monomode Optical Fibres

A. Usman, J. Osman, D. R. Tilley

Abstract: We discuss, with illustrations, some physical significances of fifth-order nonlinear susceptibility for pulse dynamics in monomode optical fibres. The amplitude dynamic governing equation is the cubic-quintic nonlinear Schrödinger equation, (CQNLSE), which has soliton properties similar to the cubic nonlinear Schrödinger equation, (CNLSE), based on solutions by a variational method. Some differences, with regards to pulse durations in the range from 10 picoseconds to a few femtoseconds, that make CQNLSE experimentally more viable are explained.


LETTERS

Page L1PDF: Transformation equations for the kinetic energy of tardyon and photon via the Bertozzi’s experiment

B. Rothenstein, S. Popescu

Abstract: Transformation equations for the kinetic energy of an electron and of a photon are derived starting with the Bertozzi’s experiment considered from the rest frame of the experimental device and from a reference frame relative to which the device moves with constant speed. The electrons involved in this experiment move in the positive direction of the overlapped axes OX(OX’) of the two frames. This derivation is based on the transformation equation for parallel velocities. The formula accounting for the transformation of the tardyon kinetic energy has at limit with particle rest energy approaching zero and with particle speed approaching c a particular form which reminds the transformation equation for the photon (kinetic) energy.