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1Author    MikhailM. Vorob 'evRequires cookie*
 Title    Hydrophobicity Scale of Amino Acids as Determined by Absorption Millimeter Spectroscopy: Correlation with Heat Capacities ©f Aqueous Solutions  
 Abstract    Hydration indexes of protein a-amino acids were measured by the new method o f absorp­ tion millimeter spectroscopy (A M S) at 10 mm wavelength (1.05 cm-1; 31.42 G H z). This re­ gion o f electromagnetic waves, located between the region o f high-frequency dielectric spectroscopy and that o f far-infrared spectroscopy, allows to measure hydration on the basis o f different rotational and reorientational mobilities o f water in hydration shell. Contribution to hydration of the methylene group is shown to be significantly greater than that of polar -O H , -C O N H 2 and -C O O H groups, while the contribution o f the charged -C H (N +H 3)C O O _ group is even negative. The high sensitivity o f A M S method to hydrophobic hydration allows to build up the hydrophobicity scale which gives an acceptable correlation (r=0.95) with the heat capacities o f the aqueous solutions o f amino acids. Thus, millimeter absorption spectroscopy, the method of hydration determination at a molecular level (determination of V-structure o f water with lifetime -50 ps), allows to quantitatively distinguish hydration of polar and non-polar groups as well as calorimetry does at a macroscopic level. 
  Reference    Z. Naturforsch. 52c, 227—234 (1997); received June 25/November 11 1996 
  Published    1997 
  Keywords    Hydrophobicity Scale, Am ino Acid Hydration, Millimeter Spectroscopy, Heat Capacity 
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 TEI-XML for    default:Reihe_C/52/ZNC-1997-52c-0227.pdf 
 Identifier    ZNC-1997-52c-0227 
 Volume    52 
2Author    F. Da Silva3, L. Rycerza, M. Gaune-Escard3Requires cookie*
 Title    Thermodynamic Properties of EuC12 and the NaCl-EuCl2 System  
 Abstract    The temperature and enthalpy of the phase transition and fusion of EuC12 were determined and found to be 1014 K, 11.5 kJ mol-and 1125 K, 18.7 kJ mol-1 , respectively. Addition­ ally, the heat capacity of solid EuC12 was measured by Differential Scanning Calorimetry in the temperature range 306 -1085 K. The results were fitted to the linear equation C^ m = (68.27 + 0.0255 T/K) J m ol-1 K-1 in the temperature range 306 -900 K. Due to discrepancies in the liter­ ature on the temperature of fusion of EuC12, the determination of the NaCl-EuCl2 phase diagram was repeated. It consists of a simple eutectic equilibrium at Tem = 847 K with x(EuCl2) = 0.49. 
  Reference    Z. Naturforsch. 56a, 647—652 (2001); received August 1 2001 
  Published    2001 
  Keywords    Europium Dichloride, Sodium Chloride, Phase Diagram, Enthalpy of Transition, Heat Capacity 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0647.pdf 
 Identifier    ZNA-2001-56a-0647 
 Volume    56 
3Author    M. Gaune-Escard, L. RycerzRequires cookie*
 Title    Heat Capacity of K 3 LnCl 6 Compounds with Ln = La, Ce, Pr, Nd  
 Abstract    The heat capacities of the solid and liquid K 3 LnCl 6 compounds (Ln = La, Ce, Pr, Nd) have been determined by differential scanning calorimetry (DSC) in the temperature range 300 -1100 K. Their temperature dependence is discussed in terms of the phase transitions of these compounds as reported in literature. The heat capacity increases and decreases strongly in the vicinity of a phase transition but else varies smoothly. The C p data were fitted by an equation which provides a satisfactory representation up to the temperatures of C p discontinuity. The measured heat capacities were checked for consistency by calculating the enthalpy of formation of the liquid phase, which had been previously measured. The results obtained compare satisfactorily with these experimental data. 
  Reference    Z. Naturforsch. 54a, 229—235 (1999); received December 17 1998 
  Published    1999 
  Keywords    Lanthanum Chloride, Cerium Chloride, Praseodymium Chloride, Neodymium Chlo-ride, Alkali Metals Chlorides, Heat Capacity, Differential Scanning Calorimetry 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0229.pdf 
 Identifier    ZNA-1999-54a-0229 
 Volume    54 
4Author    L. Rycerz, M. Gaune-EscardRequires cookie*
 Title    Heat Capacity of the Rb 3 LnCl 6 Compounds with Ln = La, Ce, Pr, Nd  
 Abstract    The heat capacities of the solid and liquid Rb 3 LnCl 6 compounds, where Ln = La, Ce, Pr, Nd, have been determined by differential scanning calorimetry (DSC) in the temperature range 300 -1100 K. The heat capacity shows a small decrease with increasing temperature from the temperature of phase transition up to 150 -200 K above this transition for the Rb 3 CeCl 6 , Rb 3 PrCl 6 and Rb 3 NdCl 6 compounds. The measured heat capacities were used to calculate the formation enthalpy of the liquid phase. The results obtained compare satisfactorily with the known experimental data. 
  Reference    Z. Naturforsch. 54a, 397—103 (1999); received March 15 1999 
  Published    1999 
  Keywords    Lanthanum Chloride, Cerium Chloride, Praseodymium Chloride, Neodymium Chlo-ride, Alkali Metals Chlorides, Heat Capacity, Differential Scanning Calorimetry 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0397.pdf 
 Identifier    ZNA-1999-54a-0397 
 Volume    54