Authors:S. Shibata, E. Kawano, K. Kimura, T. Mine, and M. Harada
14C dating of 6 Japan cedars having the relative growing ages were made. On the basis of correlation analysis of our data to
a14C age data set, INTCAL of CALIB (Stuiver), the growing ages of these Japan cedars were estimated (BC 1090-2375). The atmospheric14C concentration (Δ14C) at their growing ages were obtained from the14C age data. The variation of Δ14C shows basically the same pattern with that of Europe or America (r=0.783).
Authors:N. Petranović, D. Minić, T. Sabo, and D. Doković
Thermal properties of facial and meridional uns-cis-[Co(eddp)gly]0.5H2O complexes were investigated by means of DSC and TG techniques. It wasshown that the processes of thermal decomposition of
these complexes are multi-stepdegradation processes, which can also be well separated into individual steps, depending onthe
molecular symmetry. Thus, the process of thermal degradation of the meridional isomerof the above complex consists of 4 well-separated
steps in the temperature interval from 100to 500C. The corresponding kinetic and thermodynamic parameters of this process
weredetermined, and a possible mechanism is discussed.
Authors:Dragica M. Minić, Maja T. Šumar-Ristović, Đenana U. Miodragović, Katarina K. Anđelković, and Dejan Poleti
The kinetics of multi-step thermal degradation of Co(II) complex with N-benzyloxycarbonyl glycinato ligand [Co(N-Boc-gly)2(H2O)4]·2H2O, in non-isothermal conditions was studied using isoconversional and non-isoconversional methods. The degradation of complex occurs in three well-separated steps involving the loss of water molecules in first step followed by two degradation steps of dehydrated complex. The dependence of Arrhenius parameters on conversion degree showed that all observed steps of thermal degradation are very complex, involving more than one elementary step, as can be expected for most solid-state heterogeneous reactions with solid reactants and solid and gaseous products. It was shown that step 1, corresponding to the dehydration, involves a series of competitive dehydration steps of differently bound water molecules complicated by diffusion. Second step involves two parallel reactions related to the loss of two identical C6H5CH2O– ligand fragments complicated by the presence of products in gaseous state. Further degradation in step 3 corresponds to complex process with a change in the limiting stage, in this case from the kinetic to the diffusion regime, connected with the presence of gaseous products diffusing through the solid product.