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Study on Coordination and Noncovalent Interactions in Cu(II), L-Aspartic acid and Adenosine-5'-monophosphate Systems

Bregier-Jarzebowska R., Gasowska A., Abd El-Latif S. T.

Polish Journal of Chemistry

2008

Vol. 82, nr 11

2057-2065

In the L-aspartic acid (Asp) and adenosine-5c-monophosphate (AMP) systems molecular complexes (Asp)Hx(AMP) are formed as a result of noncovalent dipole-ion interactions between Asp and AMP. Stability constants of particular species has been determined and the interaction centres have been identified as the deprotonated carboxyl groups and the amine group from Asp along with the phosphate group and endocyclic nitrogen atoms from AMP. At pH close to 7 an inversion in the character of the interactions takes place: in an acidic medium the N(1)H group from AMP is a positive reaction centre, while in a basic medium after deprotonation it becomes a negative reaction centre. In the ternary system of Cu(II)/Asp/AMP the formation of protonated complexes of the type Cu(Asp)Hx(AMP), heteroligand complex Cu(Asp)(AMP) and hydroxocomplex Cu(Asp)(AMP)(OH) have been observed to form. The modes of coordination have been established on the basis of the spectroscopic data and equilibrium studies. At low pH the introduction of copper(II) ions to the binary system does not change the sites of intermolecular noncovalent interactions of the bioligands. Start ing from pH near 4, the presence of Cu(II) ions totally eliminates the noncovalent interactions between bioligands observed in the Asp/AMP binary systems.

Studies on a low energy plasma focus discharge

Allam T. M., Abd El-Latif S. T., Soliman H. M.

Nukleonika

2007

Vol. 52, nr 3

87-91

This paper is devoted to the experimental and theoretical study of plasma current sheath behavior for a low energy plasma focus device operating at a filling nitrogen gas pressure of 3.3 torr, and at a stored energy of 1.2 kJ. Axial distribution profiles of plasma current sheath (PCS) characteristics such as propagation velocity Vz, acceleration az, azimuthal magnetic field induction Btheta, and magnetic force per unit volume Fz/m3 along the coaxial electrodes system was performed from a magnetic probe and miniature Rogovsky coil signals. The experimental results showed that the axial distribution of Vz, az, Btheta and Fz has approximately the same profile and the maximum value of these parameters was detected nearly at a mid-distance of coaxial electrodes system. Theoretical description of PCS dynamics at the axial phase, based on a snowplough, was estimated as a function of discharge time. These data were compared with the received experimental results.