Magnetic and petrochemical properties of rocks from the Red Sea rift zone

The magnetic and petrochemical properties of basalts dredged from the rift zone at the southern part of the Red Sea at approximately 18° N are studied. The conditions of their formation and evolution are elucidated. The formation of basalts is found to occur in two stages differing in their magma supply rates and redox conditions. Special features of magnetic behavior and the anomalous geomagnetic field in the region were used to determine the sites where the rocks had experienced strong thermodynamic effects (tectonic strain, deformation, heating, etc.). The conditions in which natural remanent magnetization of the basalts was formed are estimated.     

Protonation constant of salicylidene (N-benzoyl)glycyl hydrazone and its coordination behaviour towards some bivalent metal ions

Protonation constant of an unsymmetrical Schiff base, salicylidene(N-benzoyl)glycyl hydrazone (SalBzGH), and formation constants of its complexes have been determined potentiometrically at different temperatures in aqueous dioxane medium. Complexes of SalBzGH with VO(IV), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) have been prepared. Elemental analyses, pH-metric, molar conductance, magnetic susceptibility, electronic, IR, ESR, XRD (powder) and NMR studies have been carried out to study the coordination behaviour of SalBzGH toward these metal ions. pH-metric and 1H NMR studies show the presence of two dissociable protons in the ligand. IR and NMR spectra suggest the tridentate nature of the ligand, coordinating as a uninegative species in the Mn(II) complex and as a dinegative species in all the other complexes. Presence of two different conformers of the ligand at room temperature and stabilization of a single conformer upon complex formation have been established from¹H NMR spectra of the metal-free ligand, Zn(II) and Hg(II) complexes recorded at 296 K. Electronic and ESR spectra indicate highly distorted tetragonal geometry for VO(IV) and Cu(II) complexes. XRD powder patterns of the Zn(II) complexes are indexed for an orthorhombic crystal system.     

Spectral analysis of the precessional switching of the magnetization in an isotropic thin film

We study how a magnetic field step triggers the precessional switching of the magnetization in an isotropic thin film. Using a variational approach, we make an analytical estimate of the switching frequency. We compare it to more general analytical models, and to the results obtained numerically by direct integration of the equations of motion. We show that the periodic motions of the three magnetization components can be described satisfactorily with truncated Fourier expansions, indicating a relatively high spectral purity of the magnetic response. Our analytical expressions are simple enough to be physically transparent at first sight, in contrast to the results of the more elaborate models that treat also anisotropy.     

Quenching of fluorescence from Na(32P) and K(42P) atoms following photodissociation of NaCl and KCl at 193 nm

 Quenching of fluorescence from Na(3² P) and K(4² P) atoms by various collision partners was studied at 973 and 1273K. Excited alkali atoms were produced photolytically by excimer laser light at 193nm. For each collision pair, the appropriate relative velocity was computed and used to evaluate the quenching cross-section from the measured rate constants. Cross sections for CO₂, O₂ and N₂ are large (10–60Ų) while for Ar, the values are <1 Ų. The results are compared with those of previous investigations as a function of relative velocity. Finally, implications for combustion diagnostics are briefly discussed. Received: 29 March 1996     

A method for wave decomposition in computations for nonlinear dynamical three-dimensional towing systems

We propose a new method for computing multimode wave interactions in towing systems; our method is based on wave splitting of the equations of a model in such a way that each computational step requires computation for only one mode. The efficiency of the method is demonstrated by analysis of a concrete towing system with a turning towboat. Translated fromDinamicheskic Sistermy. Vol. 12, pp. 55–64, 1993.