Slobodan Gadzuric

Chemometric estimation of post-mortem interval based on Na+ and K+ concentrations from human vitreous humour by linear least squares and artificial neural networks modelling

The subject of this paper is to determine the post-mortem interval (PMI) using the data obtained by potentiometric measurements of the electrolyte concentrations (potassium and sodium) in human vitreous humour. The data were processed by linear least squares (LLS) and artificial neural network (ANN) procedures. The LLS mathematical models have been developed as calibration models for prediction of the PMI. The quality of the models was validated by the leave one out (LOO) technique and by using an external data set. High agreement between experimental and predicted PMI values indicated the good quality of the derived models. Additionally, we analysed the influence of various factors (the cause of death, sex, differences between electrolyte concentrations in left and right eye) on the accuracy and reliability of obtained PMI. The ANN method was based on 174 forensic cases with different causes of death and known PMI ranging from 3.1–24.1 hours. The external data sets corresponding to 40 selected forensic cases were tested. Excellent correlation between experimental PMI and PMI predicted by ANN was obtained with a coefficient of correlation r2=0.9611. In comparison to the LLS regression method applied on the complete available data, the prediction of PMI with ANN was improved by1.66 hours.

Electrical conductivity of molten binary NdBr3 - alkali bromide mixtures

Electrical conductivity of liquid binary NdBr3 - alkali metal bromide mixtures was measured as a function of temperature over the whole composition range. Prior to these measurements, NdBr3 and alkali bromides were reinvestigated: a new assessment of literature data was made because of the discrepancy with reference values on NdBr3, LiBr and CsBr. The classical Arrhenius equation describes well our electrical conductivity data for mixtures. These results are discussed in terms of complex formation in the melts.

Electronic Spectra and Stability of Cobalt Halide Complexes in Molten Calcium Nitrate Tetrahydrate

The complex formation between cobalt(II) and chloride and bromide ions in molten calcium nitrate tetrahydrate at different temperatures has been studied by a spectrophotometric technique. Addition of halide ions to cobalt(II) nitrate solution in calcium nitrate tetrahydrate caused a pronounced shift of the absorption maximum toward lower energies and a large increase of absorption intensity, indicating a change from octahedral to a tetrahedral co-ordination. The change of co-ordination depends on temperature and halide concentration. Stability constants for the [Co(NO3)4]2−, [Co(NO3)2X2]2− and [CoX4]2− complexes at 40 and 70 ◦C and the corresponding species spectra are reported.

Phase Diagram and Electrical Conductivity of CeBr3-KBr

This paper continues our research program on lanthanide halide-alkali metal halide systems. Differential scanning calorimetry (DSC) was used to investigate the phase equilibria of the CeBr3-KBr system. This system is characterized by the two congruently melting compounds K3CeBr6 and K2CeBr5 and the three eutectics located at the CeBr3mole fractions 0.193 (837 K), 0.295 (855 K) and 0.555 (766 K). K3CeBr6 forms at 775 K and melts congruently at 879 K with the related enthalpies 54.5 and 41.7 kJ mol−1, respectively. K2CeBr5 melts congruently at 874 K with the enthalpy 82.4 kJ mol−1. The electrical conductivity was measured of all CeBr3-KBr mixtures and of the pure components down to temperatures below solidification. The experimental determinations were conducted over the entire composition range in steps of about 10 mol%. The specific electrical conductivity decrease with increasing CeBr3 concentration, with significantly larger conductivity changes in the potassium bromide-rich region. The results are discussed in terms of possible complex formation.

Multivariate Analysis for Chemistry-Property Relationships in Molten Salts

Abstract We systematically analyze the molten salt database of Janz to gain a better understanding of the relationship between molten salts and their properties. Due to the multivariate nature of the database, the intercorrelations amongst the molten salts and their properties are often hidden and defining them is challenging. Using principal component analysis (PCA), a data dimensionality reduction technique, we have effectively identified chemistry-property relationships. From the various patterns in the PCA maps, it has been demonstrated that information extracted with PCA not only contains chemistryproperty relationships of molten salts, but also allows us to understand bonding characteristics and mechanisms of transport and melting, which are difficult to otherwise detect.

Heat Capacity and Thermodynamic Properties of LaBr3 at 300 – 1100 K

The heat capacity of solid and liquid LaBr3 was measured by Differential Scanning Calorimetry (DSC) in the temperature range 300 - 1100 K. The obtained results were fitted by a polynomial temperature dependence. The enthalpy of fusion of LaBr3 was also measured. By combination of these results with the literature data on the entropy, S0m (LaBr3, s, 298.15 K) and the standard molar enthalpy of formation, ΔformH0m (LaBr3, s, 298.15 K), the thermodynamic functions of lanthanum tribromide were calculated up to 1300 K

Compound formation in lanthanide–alkali metal halide systems

Abstract The phase diagrams of trivalent lanthanide–alkali metal halide systems range from simple eutectic systems to systems with one or several congruently or incongruently melting compounds. Using both literature information and the authors’ extensive experimental results, the LnX3–MX binary mixture phase diagrams were screened in terms of the IPM+/IPLn3+ ratio (IPi: zi/ri; zi: ionic charge; ri: ionic radius; Ln: lanthanide, X: halide and M: alkali metal). A similar approach was conducted on the divalent LnX2–MX lanthanide–alkali metal halide phase diagrams ranging from simple eutectic to one or more congruently melting compounds. Lanthanides being widely used as simulants of actinides, this classification can constitute a useful predictive tool for those still unexplored systems.

Thermodynamics of Lead(II) Halide Complex Formation in Calcium Nitrate Tetrahydrate -Acetamide Melts

Abstract The complex formation between lead(II) ions and chloride and bromide ions in melts of C a(N 03) 2 • 4 H2O • αCH3CONH2 has been studied at different temperatures between 30 and 70 °C. The formation constants of the complexes PbX+ and PbX2 (X = Cl, Br) were determined from em f measurements by means of Ag/AgX electrodes. The dependence of the formation constants for PbCl+ on the solvent melt composition has been analysed. The thermodynamic parameters ΔH011 and ΔS011 for PbX+ complex formation have been estimated. The parameters are compared with the literature data for the same process in dilute aqueous solutions and in some hydrated and anhydrous salt melts.