Neutron activation analysis for determination of metal ions in biological fluids of patients after CoCrMo arthroplasty

Determination of metals and trace elements in patients with total knee or hip arthroplasty with CoCrMo alloy was performed. Blood, urine and cerebrospinal fluid (CSF) samples were analyzed and compared with samples from healthy people. Levels of Co, Cr as well as Na, Ca, Fe, Zn, Se, Rb, Sb and Br were determined by means of neutron activation analysis. The values of Cr and Co of the blood and urine measurements were elevated in patients with replacement, and according to the statistical analysis, significant differences of the elements Zn, Br, Co and Sb were found in the CSF (p?<?0.05).

     

A quasi lattice-local composition model for the excess Gibbs free energy of liquid mixtures

Two new expressions for the excess Gibbs energy of liquid mixtures are derived from Guggenheim's quasi-lattice model and Wilson's local composition concept. These are called the Local Surface Guggenheim equation (LSG) and the Local Composition Guggenheim equation (LCG). The LSG equation is similar, but not identical to UNIQUAC. The new equations require only two adjustable parameters per binary, and no higher-order parameters for extension to multicomponent systems.A critical discussion is given of Guggenheim's quasi-lattice expression for the excess Gibbs energy of athermal mixtures. This expression gives the combinatorial contribution to the new equations.A new method is proposed in the evaluation of the pure component structural parameters, independent of particular assumptions about the lattice parameters.The application of the LSG and the LCG equations to practical problems of phase-equilibria is considered in detail.