Thermodynamic properties of alloys binary In—Pr (Nd) and ternary In—Pr (Nd)—Ni systems

The thermochemical properties of In—Pr system melts in the range of compositions 0 < xIn < 0,4 and In—Nd in the whole concentration range at 1573 ± 1 K were investigated by isoperibolic calorimetry. The obtained data for the In—Pr system melts were extrapolated to the unexplored concentration interval, taking into account that at xPr = 1 the integral and partial mixing for Pr enthalpy are equal to zero. It was found that the first partial for Pr and the minimum enthalpy of mixing are equal to –139 ± 11 and –40,3 ± 0,2 kJ / mol, respectively. For the In—Nd system the first partial for In and Nd, the minimum enthalpy of mixing is equal to −131,7 ± 11, −140,6 ± 12 і –43,3  0,2 kJ / mol, respectively. Comparison of ΔHmin, melts of the five previously studied In—Ln systems from the ordinal number Ln (zLn) together with the data obtained in this work showed that they are described by a single trend line. For ΔHmin of melts of In—Eu (Yb) systems there are very insignificant deviations from the trend line. But for the size factor, these deviations from the trend line are more significant. The enthalpies of formation of some intermetallics of In—Ln systems are known, and most of them belong to the compound LnIn3. But there is no complete agreement between these data. The results of the most modern work show less dependence on the serial number of lanthanide and are more exothermic for heavy lanthanides, compared with other data. Keywords: thermochemical properties, compounds, melts, In, Pr, Nd.

Enthalpies of mixing in ternary Al–Gd–Mn liquid alloys

The enthalpies of mixing in liquid alloys of the ternary Al–Gd–Mn system were determined over a wide range of compositions by means of isoperibolic calorimetry at 1650 K. The measurements of the partial enthalpies of components were performed along five sections: for the ΔH̅ Al (sections with x Gd/x Mn = 0.30/0.70 and 0.65/0.35 for x Al changed from 0 up to 0.30); for the ΔH̅ Gd (x Al/x Mn = 0.80/ 0.20 and 0.50/0.50 for x Gd changed from 0 up to 0.30); for the ΔH̅ Mn (x Al/x Gd = 0.29/0.71 for x Mn changed from 0 up to 0.26). The enthalpies of mixing in the ternary system were found to be exothermic and steadily increasing in absolute values from the Mn corner towards the Al–Gd constituent binary system, reaching the minimum value of approximately – 37 kJ · mol–1 in the vicinity of the Al0.6Gd0.4 composition, evidently related to the formation of stable Al2Gd phase.

The enthalpies of mixing of ternary liquid Ag-Ca-Ge alloys

Partial and integral enthalpies of mixing of the ternary Ag–Ca–Ge melts were determined for the first time by the high-temperature isoperibolic calorimetry at 1300–1550 K. The experiments were performed for six sections with a constant ratio of two components up to the molar fraction of the third component equal to 0.3. The enthalpies of mixing in this ternary system are exothermic values which increase in absolute value from the Ag corner of the concentration triangle towards the constituent binary Ca–Ge system. The minimum value of the integral enthalpy of mixing was obtained for Ca0.6Ge0.4 composition of the Ca–Ge binary system (about –58.00 kJ mol–1). The enthalpies of mixing of the ternary Ag–Ca–Ge melts are calculated for the whole concentration triangle by the Redlich-Kister-Muggianu method, taking into account the term of specific ternary interaction defined from our experimental data. The topology of the isoenthalpies of mixing is determined.

Use of Isothermal and Isoperibolic Calorimetry to Study the Effect of Zinc on Hydration of Cement Blended with Fly Ash

Increasing utilization of secondary raw materials and alternative fuels results in increasing contents of metals in cements. Zinc is one of these elements. It comes to cement with secondary raw materials such as slag or fly ash or by the utilization of used tires as an alternative fuel. Zinc ions significantly prolong the hydration process in cement. This work deals with the influence of zinc ions in the form of very poorly soluble ZnO salt and easily soluble ZnCl2 and Zn(NO3)2 on the hydration of cement blended with fly ash. Zinc was dosed in the range of 0.05%, 0.1%, 0.5% and 1% of cement weight. The effect of zinc on hydration was monitored by isothermal and isoperibolic calorimetry. A 15% addition of fly ash to cement mainly causes further retardation of hydration reactions due to the reactions of fly ash particles with Ca2+ ions from cement. The strongest effect on the hydration retardation from all investigated compounds showed in ZnO as it dissolves very slowly. On the contrary, for the dosage of 1% of zinc in the form of ZnCl2 significant acceleration of hydration occurred. In this work, a synergistic effect on the prolongation of hydration with a combination of cement, zinc and fly ash was demonstrated. The lengths of induction periods were assessed from detected calorimetric curves and from these lengths the curves were gained by fitting with the exponential function. Final products were next analyzed using X-ray diffraction.

Possibilities of Use of Isothermal and Isoperibolic Calorimetry to Study the Effect of Zinc on Hydration of Cement Blended with Fly Ash

Increasing utilization of secondary raw materials and alternative fuels results in increasing contents of metals in cements. One of elements, the content of which keeps rising in cement is zinc. It comes to cement with secondary raw materials such as slag or fly ash or by the utilization of used tires as an alternative fuel. Zinc ions significantly prolong the hydration process in cement. This work deals with the influence of zinc ions in the form of very poorly soluble ZnO salt and easily soluble ZnCl2 and Zn(NO)3 on the hydration of cement blended with fly ash. Zinc was dosed in the range of 0.05, 0.1, 0.5 a 1% of cement weight. Final products were next analyzed using X-Ray Diffraction.

Enthalpies of mixing in binary Cu–Eu and ternary Al–Cu–Eu liquid alloys

The enthalpies of mixing in liquid alloys of the binary Cu-Eu and ternary Al-Cu-Eu systems were determined over a wide range of compositions by means of isoperibolic calorimetry in the temperature range 1 300 - 1450 K. The enthalpies of mixing in the Cu-Eu system demonstrate small exothermic effects (ΔHmin = -4.1 ± 0.5 kJ · mol-1at xCu = 0.70). The measurements for the liquid ternary Al- Cu-Eu alloys were performed along five sections (xCu/ xEu = 0.70/0.30; 0.50/0.50 and 0.27/0.73 for xAl changed from 0 up to 0.30 and xAl/xEu = 0.20/0.80 and 0.47/0.53 for xCu changed from 0 up to 0.30). The enthalpies of mixing in the ternary system were found to be exothermic and increasing in absolute values from the Al corner towards the Al0.40Cu0.60-Al0.60Eu0.40section and from the constituent binary Cu-Eu system towards the same section. The minimum value of the integral enthalpy of mixing is expected in the vicinity of the Al0.6Eu0.4composition of the binary constituent Al-Eu system (about -23.00 kJ · mol-1).

Thermal analysis of synovial fluids in different stages of osteoarthritis and after bacterial infections

The analysis of synovial fluid is an important method in diagnosing and handling septic arthritis. To achieve a quick diagnosis could be a great advantage in the therapy. The differential scanning calorimetry (DSC) proved to be a useful technique in the differential diagnosis of tumors using blood plasma or sera. The aim of this paper is to show up some characteristic thermal parameters in the diagnosis of different grades of arthritis, which are in good agreement with the severity of disease checked by conventional X-ray supported grading. To follow the effect of different bacterial strains, the synovial fluids were inoculated by three types of bacterial strains (with 103–105 CFU mL−1 concentrations) at 37 °C and stored trough 24 h. After that, they were denatured in 20–90 °C temperature range with 0.3 K min−1 scanning rate. The change in the maximum denaturation temperature (Tm) and calorimetric enthalpy (∆H) monitored the severity of sepsis and depended on the type of bacteria. The proliferation characteristics of bacteria should be strain specific. The synovial fluid samples inoculated with the most frequently occurring bacteria were monitored in isotherm mode (isoperibol calorimeter) at 37 °C up to the end of the proliferation. The isoperibolic scans clearly demonstrated specific, concentration-dependent representative curves in case of each bacterium (duration of proliferation, maximum of proliferation rates, etc.). Therefore, thermal analysis of human synovial fluid samples by DSC or isoperibolic calorimetry could be a useful tool in the staging of osteoarthritis and the diagnostics of septic arthritis.

Electrochemical Isoperibolic Calorimetry for D2O Electrolysis

Equations developed for isoperibolic electrochemical calorimetry were tested for the electrolysis of D2O in an open calorimetric cell. The derivatives of these equations gave correct values within the experimental error range for the important rate of change of the cell temperature with time (dT/dt). In addition, these calorimetric equations were also tested directly in determining the enthalpy change (ΔH) for the D2O electrolysis reaction. The mean experimental value at 298.15 K was ΔH = 294.4 ± 0.3 kJ/mole. This compares favorably (within 0.10%) with the literature value of ΔH = 294.600 kJ/mole. The accuracy of these ΔH measurements could be even further improved by more accurate cell voltage and cell temperature measurement. <br>

Electrochemical Isoperibolic Calorimetry for D2O Electrolysis

Equations developed for isoperibolic electrochemical calorimetry were tested for the electrolysis of D2O in an open calorimetric cell. The derivatives of these equations gave correct values within the experimental error range for the important rate of change of the cell temperature with time (dT/dt). In addition, these calorimetric equations were also tested directly in determining the enthalpy change (ΔH) for the D2O electrolysis reaction. The mean experimental value at 298.15 K was ΔH = 294.4 ± 0.3 kJ/mole. This compares favorably (within 0.10%) with the literature value of ΔH = 294.600 kJ/mole. The accuracy of these ΔH measurements could be even further improved by more accurate cell voltage and cell temperature measurement. <br>

Application of Isothermal and Isoperibolic Calorimetry to Assess the Effect of Zinc on Hydration of Cement Blended with Slag

This work deals with the influence of zinc on cement hydration. The amount of zinc in cement has increased over recent years. This is mainly due to the utilization of solid waste and tires, which are widely used as a fuel in a rotary kiln. Zinc can also be introduced to cement through such secondary raw materials as slag, due to increased recycling of galvanized materials. The aim of this work was to determine the effect of zinc on the hydration of Portland cement, blended with ground blast furnace slag (GBFS). This effect was studied by isothermal and isoperibolic calorimetry. Both calorimetry methods are suitable for measurements during the first days of hydration. Isoperibolic calorimetry monitors the hydration process in real-life conditions, while isothermal calorimetry does so at a defined chosen temperature. Zinc was added to the cement in the form of two soluble salts, namely Zn(NO3)2, ZnCl2, and a poorly soluble compound, ZnO. The concentration of added zinc was chosen to be 0.05, 0.1, 0.5, and 1mass percent. The amount of GBFS replacement was 15% of cement dosage. The newly formed hydration products were identified by X-ray diffraction method (XRD).