Thermal analysis, phase transitions and molecular reorientations in [Sr(OS(CH3)2)6](ClO4)2

Thermal analysis (TG/DTG/QMS), performed for [Sr(OS(CH₃)₂)₆](ClO₄)₂ in a flow of argon and in temperature range of 295–585 K, indicated that the compound is completely stable up to ca. 363 K, and next starts to decompose slowly, and in the temperature at ca. 492 K looses four (CH₃)₂SO molecules per one formula unit. During further heating [Sr(DMSO)₂](ClO₄)₂ melts and simultaneously decomposes with explosion. Differential scanning calorimetry (DSC) measurements performed in the temperature range of 93–370 K for [Sr(DMSO)₆](ClO₄)₂ revealed existence of the following phase transitions: glass ? crystal phase Cr5 at T _g  ≈ 164 K (235 K), phase Cr5 → phase Cr4 at $ T_{\text{c6}}^{\text{h}} $  ≈ 241 K, phase Cr4 → phase Cr3 at $ T_{\text{c5}}^{\text{h}} $  ≈ 255 K, phase Cr3 → phase Cr2 at $ T_{\text{c4}}^{\text{h}} $  ≈ 277 K, phase Cr2 ? phase Cr1 at $ T_{\text{c3}}^{\text{h}} $  ≈ 322 K and $ T_{\text{c3}}^{\text{c}} $  ≈ 314 K, phase Cr1 ? phase Rot2 at $ T_{\text{c2}}^{\text{h}} $  ≈ 327 K and $ T_{\text{c2}}^{\text{c}} $  ≈ 321 K and phase Rot2 ? phase Rot1 at $ T_{\text{c1}}^{\text{h}} $  ≈ 358 K and $ T_{\text{c1}}^{\text{c}} $  ≈ 347 K. Entropy changes values of the phase transitions at $ T_{\text{c1}}^{\text{h}} $ and $ T_{\text{c2}}^{\text{h}} $ (?S ≈ 79 and 24 J mol^?1 K^?1, respectively) indicated that phases Rot1 and Rot2 are substantially orientationally disordered. The solid phases (Cr1–Cr5) are more or less ordered phases (?S ≈ 7, 10, 4 and 3 J mol^?1 K^?1, respectively). Phase transitions in [Sr(DMSO)₆](ClO₄)₂ were also examined by Fourier transform middle infrared spectroscopy (FT-MIR). The characteristic changes in the FT-MIR absorption spectra of the low- and high-temperature phases observed at the phase transition temperatures discovered by DSC allowed us to relate these phase transitions to the changes of the reorientational motions of DMSO ligands and/or to the crystal structure changes.     

Spectroscopic Studies on the Thermodynamics of the Complexation of Trivalent Curium with Propionate in the Temperature Range from 20 to 90 °C

The thermodynamics of the stepwise complexation reaction of Cm(III) with propionate was studied by time resolved laser fluorescence spectroscopy (TRLFS) and UV/Vis absorption spectroscopy as a function of the ligand concentration, the ionic strength and temperature (20–90 °C). The molar fractions of the 1:1 and 1:2 complexes were quantified by peak deconvolution of the emission spectra at each temperature, yielding the log₁₀ $ K_{n}^{\prime } $ values. Using the specific ion interaction theory (SIT), the thermodynamic stability constants log₁₀ $ K_{n}^{0} (T) $ were determined. The log₁₀ $ K_{n}^{0} (T) $ values show a distinct increase by 0.15 (n = 1) and 1.0 (n = 2) orders of magnitude in the studied temperature range, respectively. The temperature dependency of the log₁₀ $ K_{n}^{0} (T) $ values is well described by the integrated van’t Hoff equation, assuming a constant enthalpy of reaction and $ \Updelta_{\text{r}} C^\circ_{{p,{\text{m}}}} = 0, $ yielding the thermodynamic standard state $ \left( {\Updelta_{\text{r}} H^\circ_{\text{m}} ,\Updelta_{\text{r}} S^\circ_{\text{m}} ,\Updelta_{\text{r}} G^\circ_{\text{m}} } \right) $ values for the formation of the $ {\text{Cm(Prop)}}_{n}^{3 - n} $ , n = (1, 2) species.     

Excess Molar Volumes and Excess Isentropic Compressibilities of o-Toluidine + Tetrahydropyran with Pyridine or Benzene or Toluene Ternary Mixtures at 298.15, 303.15 and 308.15 K

The densities, ρ ₁₂₃, and speeds of sound, u ₁₂₃, of ternary o-toluidine (OT, 1) + tetrahydropyran (THP, 2) + pyridine (Py) or benzene or toluene (3) mixtures have been measured as a function of composition at 298.15, 303.15 and 308.15 K. Values of the excess molar volumes, $ V_{123}^{\text{E}} , $ and excess isentropic compressibilities, $ (\kappa_{\text{S}}^{\text{E}} )_{123} , $ of the studied mixtures have been determined by employing the measured experimental data. The observed thermodynamic properties were fitted with the Redlich–Kister equation to determine adjustable ternary parameters and standard deviations. The $ V_{123}^{\text{E}} $ and $ (\kappa_{\text{S}}^{\text{E}} )_{123} $ values were also analyzed in terms of Graph theory. It was observed that Graph theory correctly predicts the sign as well as magnitude of $ V_{123}^{\text{E}} $ and $ (\kappa_{\text{S}}^{\text{E}} )_{123} $ values of the investigated mixtures. Analysis of the data suggests strong interactions and a more close packed arrangement in OT (1) + THP (2) + Py (3) mixtures as compared to those of the OT (1) + THP (2) + benzene (3) or toluene (3) mixtures. This may be due to the presence of a nitrogen atom in Py which results in stronger interactions for the OT:THP molecular entity as compared to those with benzene or toluene.     

Thermodynamic study of metal corrosion and inhibitor adsorption processes in copper/N-1-naphthylethylenediamine dihydrochloride monomethanolate/nitric acid system: part 2

N-1-Naphthylethylenediamine dihydrochloride monomethanolate (N-NEDHME) was tested as a corrosion inhibitor for copper in 2 M HNO₃ solution using the standard gravimetric technique at 303–343 K. N-NEDHME acts as an inhibitor for copper in an acidic medium. Inhibition efficiency increases with increase in concentration of N-NEDHME but decreases with a rise in temperature. Thermodynamic parameters such as adsorption heat ( $ \Updelta H_{\text{ads}}^\circ $ ), adsorption entropy ( $ \Updelta S_{\text{ads}}^\circ $ ) and adsorption free energy ( $ \Updelta G_{\text{ads}}^\circ $ ) were obtained from experimental data of the temperature studies of the inhibition process at five temperatures ranging from 303 to 343 K. Kinetic parameters activation such as $ E_{a} $ , $ \Updelta H_{\text{a}}^\circ $ , $ \Updelta S_{\text{a}}^\circ $ and pre-exponential factors have been calculated and are discussed. Adsorption of N-NEDHME on the copper surface in 2 M HNO₃ follows the Langmuir isotherm model.     

Crystal structure and thermodynamic properties of dipotassium diiron(III) hexatitanium oxide

In the present work, the temperature dependence of heat capacity of dipotassium diiron(III) hexatitanium oxide has been measured for the first time in the range from 10 to 300 K by means of precision adiabatic vacuum calorimetry. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity $ C_{p}^{ \circ } (T) $ , enthalpy $ H^{ \circ } (T) - H^{ \circ } (0) $ , entropy $ S^{ \circ } (T) - S^{ \circ } (0), $ and Gibbs function $ G^{ \circ } (T) - H^{ \circ } (0) $ for the range from T → 0 to 300 K. The structure of K₂Fe₂Ti₆O₁₆ is refined by the Rietveld method: space group I4/m, Z = 1, a = 10.1344(2) Å, c = 2.97567(4) Å, V = 305.618(7) Å³. The high-temperature X-ray diffraction was used for the determination of coefficients of thermal expansion.     

Molecular Interactions in 1-Ethyl-3-Methylimidazolim Tetrafluoroborate + Amide Mixtures: Excess Molar Volumes, Excess Isentropic Compressibilities and Excess Molar Enthalpies

The densities, ρ ₁₂, and speeds of sound, u ₁₂, of 1-ethyl-3-methylimidazolium tetrafluoroborate (1) + N-methylformamide or N,N-dimethylformamide (2) binary mixtures at (293.15. 298.15. 303.15, 308.15 K), and excess molar enthalpies, $ H_{12}^{\text{E}} $ H 12 E , of the same mixtures at 298.15 K have been measured over the entire mole fraction range using a density and sound analyzer (Anton Paar DSA-5000) and a 2-drop microcalorimeter, respectively. Excess molar volume, $ V_{12}^{\text{E}} $ V 12 E , and excess isentropic compressibility, $ \left( {\kappa_{S}^{\text{E}} } \right)_{12} $ ( κ S E ) 12 , values have been calculated by utilizing the measured density and speed of sound data. The observed data have been analyzed in terms of: (i) Graph theory and (ii) the Prigogine–Flory–Patterson theory. Analysis of the $ V_{12}^{\text{E}} $ V 12 E data in terms of Graph theory suggest that: (i) in pure 1-ethyl-3-methylimidazolium tetrafluoroborate, the tetrafluoroborate anion is positioned over the imidazoliun ring and there are interactions between the hydrogen atom of (C–H{edge}) and proton of the –CH₃ group (imidazolium ring) with fluorine atoms of tetrafluoroborate anion, and (ii) (1 + 2) mixtures are characterized by ion–dipole interactions to form a 1:1 molecular complex. Further, the $ V_{12}^{\text{E}} $ V 12 E , $ H_{12}^{\text{E}} $ H 12 E and $ \left( {\kappa_{S}^{\text{E}} } \right)_{12} $ ( κ S E ) 12 values determined from Graph theory compare well with their measured experimental data.     

Density functional study on structures, stabilities, and electronic properties of size-selected Pd n Si q (n = 1–7 and q = 0, +1, −1) clusters

The density functional theory (DFT) calculations within the framework of generalized gradient approximation have been employed to systematically investigate the geometrical structures, stabilities, and electronic properties of Pd _n Si ^q (n = 1–7 and q = 0, +1, ?1) clusters and compared them with the pure ${\text{Pd}}_{n + 1}^{q}$ (n = 1–7 and q = 0, +1, ?1) clusters for illustrating the effect of doping Si atom into palladium nanoclusters. The most stable configurations adopt a three-dimensional structure for both pure and Si-doped palladium clusters at n = 3–7. As a result of doping, the Pd _n Si clusters adopt different geometries as compared to that of Pd _n+1. A careful analysis of the binding energies per atom, fragmentation energies, second-order difference of energies, and HOMO–LUMO energy gaps as a function of cluster size shows that the clusters ${\text{Pd}}_{4}^{ + }$ , ${\text{Pd}}_{4}$ , ${\text{Pd}}_{8}^{ - }$ , ${\text{Pd}}_{5} {\text{Si}}^{0, + , - }$ , and ${\text{Pd}}_{7} {\text{Si}}^{0, + , - }$ possess relatively higher stability. There is enhancement in the stabilities of palladium frameworks due to doping with an impurity atom. In addition, the charge transfer has been analyzed to understand the effect of doped atom and compared further.     

Synergistic extraction of europium and americium into nitrobenzene by using hydrogen dicarbollylcobaltate and bis(diphenylphosphino)methane dioxide

Extraction of microamounts of europium and americium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^?) in the presence of bis(diphenylphosphino)methane dioxide (DPPMDO, L) has been investigated. The equilibrium data have been explained assuming that the species $ {\text{HL}}^{ + } $ , $ {\text{HL}}_{2}^{ + } $ , $ {\text{ML}}_{2}^{3 + } $ , $ {\text{ML}}_{3}^{3 + } $ and $ {\text{ML}}_{4}^{3 + } $ (M³⁺ = Eu³⁺, Am³⁺) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It was found that the stability constants of the corresponding complexes $ {\text{EuL}}_{n}^{3 + } $ and $ {\text{AmL}}_{n}^{3 + } $ , where n = 2, 3 and L is DPPMDO, in water–saturated nitrobenzene are comparable, whereas in this medium the stability of the cationic species $ {\text{AmL}}_{4}^{3 + } $ (L = DPPMDO) is somewhat higher than that of $ {\text{EuL}}_{4}^{3 + } $ with the same ligand L.     

Pre-formulation of an oral cyclosporine free of surfactant

The purpose of this study was to develop a new oral cyclosporine A (CsA) formulation free of surfactant cremophor using cyclodextrin terpolymers (P-αβ-CD, P-βγ-CD and P-αγ-CD) as excipients in attempt to enhance its stability, dissolution rate and eliminate surfactant side effects. Two spray-dried dispersions (SDDs) containing poorly water-soluble CsA were prepared with either P-αβ-CD, P-βγ-CD or P-αγ-CD using water ( $ F_{{{\text{H}}_{2} {\text{O}}}} $ ) and ethanol (F _EOH) via spray-drying technique and characterized by scanning electron microscopy, powder X-ray diffraction, particle size distribution, circular dichroism (CD) and nuclear magnetic resonance along with the dissolution study which was compared to Neoral^® and Sandimmune^®. The results showed an interaction between CsA and P-αβ-CD, P-βγ-CD and P-αγ-CD without secondary structure change of CsA. The order of the CsA release from the terpolymers was ranked as follows: P-αγ-CD/CsA ( $ F_{{{\text{H}}_{2} {\text{O}}}} $ ) = Neoral^® > P-βγ-CD/CsA ( $ F_{{{\text{H}}_{2} {\text{O}}}} $ ) > P-αβ-CD/CsA ( $ F_{{{\text{H}}_{2} {\text{O}}}} $ ) > P-αγ-CD/CsA (F _EOH) > Sandimmune^® > P-αβ-CD/CsA (F _EOH) > P-βγ-CD/CsA (F _EOH). The results of ( $ F_{{{\text{H}}_{2} {\text{O}}}} $ ) could be explained by hydrophilisation and absence of crystallinity of CsA while maintaining part of its crystallinity in the case of formulations (F _EOH). In summary, developed SDD formulations P-αγ-CD/CsA ( $ F_{{{\text{H}}_{2} {\text{O}}}} $ ) revealed same dissolution profile as Neoral^® and better than Sandimmune^®. These systems seem to be stable to carry cyclosporine and release it, while preserving structure and thus, potentially, also maintaining cyclosporine activity.     

The calculation of the detection efficiency in the calibration of gross alpha–beta systems

This paper presents a method for efficiency calibration of a measuring alpha–beta system PROTEAN ORTEC, MPC-2000-DP, using standard radioactive sources. The system is used to measure gross alpha–beta activity concentrations in environmental samples. The calculated efficiencies of detection were subsequently introduced in the system for two working geometries: measuring geometry—gross alpha–beta $ \varepsilon_{\alpha }^{g} $  = 31,37 ± 0.25 (%)—the alpha efficiency and $ \varepsilon_{\beta }^{g} $  = 44.94 ± 0.69 (%)—the beta efficiency, where the spillover factor is $ X_{\text{talk}}^{g} $  = 25.59 ± 0.50 (%) and measuring geometry up alpha–beta $ \varepsilon_{\alpha }^{u} $  = 36.23 ± 0.29 (%)—the alpha efficiency and $ \varepsilon_{\beta }^{u} $  = 48.53 ± 0.74 (%)—the beta efficiency, where the spillover factor is $ X_{\text{talk}}^{u} $  = 31.08 ± 0.60 (%).     

The Formation and Stability of the [FePy3Cl3]· Py Clathrate in the Pyridine–Iron(III) Chloride System: Phase Diagram and Solid–Gas Equilibria Study

The phase diagram of the pyridine–iron(III) chloride system has been studied for the 223–423 K temperature and 0–56 mass-% concentration ranges using differential thermal analysis (DTA) and solubility techniques. A solid with the highest pyridine content formed in the system was found to be an already known clathrate compound, [FePy₃Cl₃]·Py. The clathrate melts incongruently at 346.9 ± 0.3 K with the destruction of the host complex: [FePy₃Cl₃]·Py_(solid)=[FePy₂Cl₃]_(solid) + liquor. The thermal dissociation of the clathrate with the release of pyridine into the gaseous phase (TGA) occurs in a similar way: [FePy₃Cl₃]·Py_(solid)=[FePy2Cl₃]_(solid) + 2 Py_(gas). Thermodynamic parameters of the clathrate dissociation have been determined from the dependence of the pyridine vapour pressure over the clathrate samples versus temperature (tensimetric method). The dependence experiences a change at 327 K indicating a polymorphous transformation occurring at this temperature. For the process ${1 \over 2}[\hbox{FePy}_{3}\hbox{Cl}_{3}]\cdot \hbox{Py}_{\rm (solid)} = {1 \over 2}[\hbox{FePy}_{2}\hbox{Cl}_{3}]_{\rm (solid)} + \hbox{Py}_{\rm (gas)}$ in the range 292–327 K, ΔH $^{0}_{298}$ =70.8 ± 0.8 kJ/mol, ΔS $^{0}_{298}$ =197 ± 3 J/(mol K), ΔG $^{0}_{298}$ =12.2 ± 0.1 kJ/mol; in the range 327–368 K, ΔH $^{0}_{298}$ =44.4 ± 1.3 kJ/mol, ΔS $^{0}_{298}$ =116 ± 4 J/(mol K), ΔG $^{0}_{298}$ =9.9 ± 0.3 kJ/mol.     

CORAL: QSPRs of enthalpies of formation of organometallic compounds

Available on the Internet the CORAL software gives reasonable good prediction for standard enthalpy of formation for selected organometallic compounds (n = 132). The approach is tested using five random splits of the considered data into the sub-training set (n = 32–49), calibration set (n = 36–51), test set (n = 10–29), and the validation set (n = 22–41). Compounds of the validation set are not involved in building up the models. The average statistical quality of prediction is the following: correlation coefficient ( $\overline{R^{2}} )$ R 2 ¯ ) $0.991\pm 0.005$ 0.991 ± 0.005 and standard error of estimation ( $\overline{s} )$ s ¯ ) $22.9 \pm 5.6$ 22.9 ± 5.6  kJ/mol.     

A thermodynamic study of complexation of 18-crown-6 with Zn2+, Tl+, Hg2+ and {\text{UO}}^{{{\text{2 + }}}}_{{\text{2}}} cations in acetonitrile-dimethylformamide binary media and study the effect of anion on the stability constant of (18C6-Na+) complex in methanol solutions

The equilibrium constants and thermodynamic parameters for complex formation of 18-crown-6(18C6) with Zn²⁺, Tl⁺, Hg²⁺ and $ {\text{UO}}^{{{\text{2 + }}}}_{{\text{2}}} $ cations have been determined by conductivity measurements in acetonitrile(AN)-dimethylformamide(DMF) binary solutions. 18-crown-6 forms 1:1 complexes [M:L] with Zn²⁺, Hg²⁺ and $ {\text{UO}}^{{{\text{2 + }}}}_{{\text{2}}} $ cations, but in the case of Tl⁺ cation, a 1:2 [M:L₂] complex is formed in most binary solutions. The thermodynamic parameters ( $ \Delta {\text{H}}^{ \circ }_{{\text{c}}} $ and $ \Delta {\text{S}}^{ \circ }_{{\text{c}}} $ ) which were obtained from temperature dependence of the equilibrium constants show that in most cases, the complexes are enthalpy destabilized but entropy stabilized and a non-monotonic behaviour is observed for variations of standard enthalpy and entropy changes versus the composition of AN/DMF binary mixed solvents. The obtained results show that the order of selectivity of 18C6 ligand for these cations changes with the composition of the mixed solvent. A non-linear relationship was observed between the stability constants (logK_f) of these complexes with the composition of AN/DMF binary solutions. The influence of the $ {\text{ClO}}^{ - }_{{\text{4}}} $ , $ {\text{NO}}^{ - }_{{\text{3}}} $ and $ {\text{Cl}}^{ - } $ anions on the stability constant of (18C6-Na⁺) complex in methanol (MeOH) solutions was also studied by potentiometry method. The results show that the stability of (18C6-Na⁺) complex in the presence of the anions increases in order: $ {\text{ClO}}^{ - }_{{\text{4}}} $  >  $ {\text{NO}}^{ - }_{{\text{3}}} $  >  $ {\text{Cl}}^{ - } $ .     

Thermochemical Properties of n-Undecylammonium Bromide Monohydrate C11H28BrNO(s)

The crystal structure of n-undecylammonium bromide monohydrate was determined by X-ray crystallography. The crystal system of the compound is monoclinic, and the space group is P2₁/c. Molar enthalpies of dissolution of the compound at different concentrations m/(mol·kg^?1) were measured with an isoperibol solution–reaction calorimeter at T = 298.15 K. According to the Pitzer’s electrolyte solution model, the molar enthalpy of dissolution of the compound at infinite dilution ( $ \Updelta_{\text{sol}} H_{\text{m}}^{\infty } $ ) and Pitzer parameters ( $ \beta_{\text{MX}}^{(0)L} $ and $ \beta_{\text{MX}}^{(1)L} $ ) were obtained. Values of the apparent relative molar enthalpies ( $ {}^{\Upphi }L $ ) of the title compound and relative partial molar enthalpies ( $ \bar{L}_{2} $ and $ \bar{L}_{1} $ ) of the solute and the solvent at different concentrations were derived from experimental values of the enthalpies of dissolution.     

Computer-aided cooling curve thermal analysis of near eutectic Al–Si–Cu–Fe alloy

The effects of bismuth (Bi), antimony (Sb) and strontium (Sr) additions on the characteristic parameters of the evolution of aluminium dendrites in a near eutectic Al–11.3Si–2Cu–0.4Fe alloy during solidification at different cooling rates (0.6–2 °C) were investigated by computer-aided cooling curve thermal analysis (CA-CCTA). Nucleation temperature ( $ T_{\text{N}}^{{\alpha {\text{ - Al}}}} $ ) is defined with a new approach based on second derivative cooling curve. The results showed that $ T_{\text{N}}^{{\alpha {\text{ - Al}}}} $ increased with increasing cooling rate but both the growth temperature ( $ T_{\text{G}}^{{\alpha {\text{ - Al}}}} $ ) and the coherency temperature (T _DCP) decreased. Increase in the temperature difference for dendrite coherency ( $ T_{\text{N}}^{{\alpha {\text{ - Al}}}} - T_{\text{DCP}} $ ) with increasing cooling rate indicate a wider range of temperature before the dendrite can impinge on each other and higher fraction solid ( $ f_{\text{S}}^{\text{DCP}} $ ). Additions of Bi, Sb and Sr to the base alloy produced only a minor effect on $ T_{\text{N}}^{{\alpha {\text{ - Al}}}} $ . Additions of Bi and Sb resulted in an increase in fraction solid and an increase of 30 % in the value of $ T_{\text{N}}^{{\alpha {\text{ - Al}}}} \, - \,T_{\text{G}}^{{\alpha {\text{ - Al}}}} $ to almost 13 °C.     

Thermochemistry of hydroxymethylphenol isomers

The standard (p° = 0.1 MPa) molar enthalpies of formation in the crystalline state of the 2-, 3- and 4-hydroxymethylphenols, $ {{\Updelta}}_{\text{f}} H_{\text{m}}^{\text{o}} ( {\text{cr)}} = \, - ( 3 7 7. 7 \pm 1. 4)\,{\text{kJ}}\,{\text{mol}}^{ - 1} $ , $ {{\Updelta}}_{\text{f}} H_{\text{m}}^{\text{o}} ( {\text{cr) }} = - (383.0 \pm 1.4) \, \,{\text{kJ}}\,{\text{mol}}^{ - 1} $ and $ {{\Updelta}}_{\text{f}} H_{\text{m}}^{\text{o}} ( {\text{cr)}} = - (382.7 \pm 1.4)\,{\text{kJ}}\,{\text{mol}}^{ - 1} $ , respectively, were derived from the standard molar energies of combustion, in oxygen, to yield CO₂(g) and H₂O(l), at T = 298.15 K, measured by static bomb combustion calorimetry. The Knudsen mass-loss effusion technique was used to measure the dependence of the vapour pressure of the solid isomers of hydroxymethylphenol with the temperature, from which the standard molar enthalpies of sublimation were derived using the Clausius–Clapeyron equation. The results were as follows: $ \Updelta_{\rm cr}^{\rm g} H_{\rm m}^{\rm o} = (99.5 \pm 1.5)\,{\text{kJ}}\,{\text{mol}}^{ - 1} $ , $ \Updelta_{\rm cr}^{\rm g} H_{\rm m}^{\rm o} = (116.0 \pm 3.7) \,{\text{kJ}}\,{\text{mol}}^{ - 1} $ and $ \Updelta_{\rm cr}^{\rm g} H_{\rm m}^{\rm o} = (129.3 \pm 4.7)\,{\text{ kJ mol}}^{ - 1} $ , for 2-, 3- and 4-hydroxymethylphenol, respectively. From these values, the standard molar enthalpies of formation of the title compounds in their gaseous phases, at T = 298.15 K, were derived and interpreted in terms of molecular structure. Moreover, using estimated values for the heat capacity differences between the gas and the crystal phases, the standard (p° = 0.1 MPa) molar enthalpies, entropies and Gibbs energies of sublimation, at T = 298.15 K, were derived for the three hydroxymethylphenols.     

Influence of heavy metals on the early hydration of calcium sulfoaluminate

The hydration of calcium sulfoaluminate $ ( {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} ) $ in the presence of heavy metal is essential not only for applying the cement in solidification/stabilization (s/s) process, but also for preparing modern green cements from wastes containing heavy metals. In this study, the influence of gypsum, types, and concentrations of heavy metal nitrates (Pb(NO₃)₂, Cr(NO₃)₃·9H₂O, Cu(NO₃)₂·3H₂O, Zn(NO₃)₂·6H₂O) on the hydration of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ during the first 24 h were investigated by isothermal conduction calorimetry, X-ray diffraction, and thermogravimetric analysis. The addition of 20 % of gypsum to $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ leads to a rapid formation of ettringite against monosulfate and acceleration of hydration. The effects of heavy metals on the hydration of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ depend on the types of heavy metals and the addition of gypsum. Without any gypsum addition, heavy metal nitrates such as Cr, Cu, and Zn promote the hydration of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ , whereas Pb presents a strong retardation effect at the early age of $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ hydration. When 20 % of gypsum is added to $ {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} $ , heavy metals tend to accelerate the hydration of the blended pastes except Zn. However, heavy metal containing phases were not detected in this work, which needs to be supplemented by further investigations.     

Volumetric Properties of the Nucleoside Thymidine in Aqueous Solution at T = 298.15 K and p = (10 to 100) MPa

Sound speeds have been measured for aqueous solutions of the nucleoside thymidine at T = 298.15 K and at the pressures p = (10, 20, 40, 60, 80, and 100) MPa. The partial molar volumes at infinite dilution, $ V_{2}^{\text{o}} $ , the partial molar isentropic compressions at infinite dilution, $ K_{S,2}^{\text{o}} $ , and the partial molar isothermal compressions at infinite dilution, $ K_{T,2}^{\text{o}} $ $ \{ K_{T,2}^{\text{o}} = - (\partial V_{2}^{\text{o}} /\partial p)_{T} \} $ , have been derived from the sound speeds at elevated pressures using methods described in our previous work. The $ V_{2}^{\text{o}} $ and $ K_{T,2}^{\text{o}} $ results were rationalized in terms of the likely interactions between thymidine and the aqueous solvent. The $ V_{2}^{\text{o}} $ results were also compared with those calculated using the revised Helgeson–Kirkham–Flowers (HKF) equation of state.     

Densities and Volumetric Properties of Butyl Acrylate + 1-Butanol, or +2-Butanol, or +2-Methyl-1-propanol, or +2-Methyl-2-propanol Binary Mixtures at Temperatures from 288.15 to 318.15 K

The densities, ρ, of binary mixtures of butyl acrylate with 1-butanol, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol, including those of the pure liquids, were measured over the entire composition range at temperatures of (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K and atmospheric pressure. From the experimental data, the excess molar volume $ V_{\text{m}}^{\text{E}} $ V m E , partial molar volumes $ \overline{V}_{\text{m,1}} $ V ¯ m,1 and $ \overline{V}_{\text{m,2}} $ V ¯ m,2 , and excess partial molar volumes $ \overline{V}_{\text{m,1}}^{\text{E}} $ V ¯ m,1 E and $ \overline{V}_{\text{m,2}}^{\text{E}} $ V ¯ m,2 E , were calculated over the whole composition range as were the partial molar volumes $ \overline{V}_{\text{m,1}}^{^\circ } $ V ¯ m,1 ° and $ \overline{V}_{\text{m,2}}^{^\circ } $ V ¯ m,2 ° , and excess partial molar volumes $ \overline{V}_{\text{m,1}}^{{^\circ {\text{E}}}} $ V ¯ m,1 ° E and $ \overline{V}_{\text{m,2}}^{{^\circ {\text{E}}}} $ V ¯ m,2 ° E , at infinite dilution,. The $ V_{\text{m}}^{\text{E}} $ V m E values were found to be positive over the whole composition range for all the mixtures and at each temperature studied, indicating the presence of weak (non-specific) interactions between butyl acrylate and alkanol molecules. The deviations in $ V_{\text{m}}^{\text{E}} $ V m E values follow the order: 1-butanol < 2-butanol < 2-methyl-1-propanol < 2-methyl-2-propanol. It is observed that the $ V_{\text{m}}^{\text{E}} $ V m E values depend upon the position of alkyl groups in alkanol molecules and the interactions between butyl acrylate and isomeric butanols decrease with increase in the number of alkyl groups at α-carbon atom in the alkanol molecules.