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Heat capacity (C p) of the compound Sb·405Te·595 in solid and liquid states at constant pressure are calculated from the results of experimental “drop calorimetric” method. The heat of fusion of the compound is deduced. A phase transition in the solid state has been put in evidence.

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Journal of Thermal Analysis and Calorimetry
Authors: B. Lebedev, T. Kulagina, M. Ryabkov, S. Ponomarenko, E. Makeev, N. Boikov, V. Shibaev, E. Rebrov, and A. Muzafarov

Abstract  

The thermodynamic properties of carbosilane dendrimer of second generation with terminal methoxyundecylene groups were studied between 6 and 340 K by adiabatic vacuum calorimetry: the temperature dependence of the molar heat capacity Cp 0 was measured, the physical transformations were established and their thermodynamic characteristics were obtained. The experimental data were used to calculate the thermodynamic functions Cp 0 (T), H 0(T)-H 0(0), S0(T), G 0(T)-H 0(0) of the compound in the range 0 to 340 K. from the relation Cp 0 (T) the fractal dimension of the dendrimer was experimentally determined. The heat capacity of the dendrimer was compared with the corresponding additive values calculated from the properties of its constituents - a dendritic matrix (carbosilane dendrimer of second generation) and the corresponding amount of moles of methyl ester of 11-(tetramethyldisiloxy)undecanoic acid serving as terminal groups.

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Abstract  

Complex heat capacity, C p *=C p 'iC p '', of lithium borate glasses xLi2O(1–x)B2O3 (molar fraction x=0.00–0.30) has been investigated by Modulated DSC. We have analyzed the shape of C p * by the Cole-Cole plot, performed fitting by the Havriliak-Negami equation, and then determined the parameters related to the non-Debye nature of thermal relaxation. Moreover, the concentration dependence of the thermal properties has been investigated. Glass transition temperatures become higher with the increase of molar fraction of Li2O and shows the board peak around x=0.26. Temperature ranges of glass transitions become narrower with the increase of Li2O concentration.

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Journal of Thermal Analysis and Calorimetry
Authors: Igor E. Paukov, Yulia A. Kovalevskaya, Alexei E. Arzamastcev, Natalia A. Pankrushina, and Elena V. Boldyreva

Abstract

Heat capacity of methacetin (N-(4-methoxyphenyl)-acetamide) has been measured in the temperature range 5.8–300 K. No anomalies in the C p(T) dependence were observed. Thermodynamic functions were calculated. At 298.15 K, the values of entropy and enthalpy are equal to 243.1 J K−1 mol−1 and 36360 J mol−1, respectively. The heat capacity of methacetin in the temperature range 6–10 K is well fitted by Debye equation C p = AT 3. The thermodynamic data obtained for methacetin are compared with those for the monoclinic and orthorhombic polymorphs of paracetamol.

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Abstract  

We measure the frequency dependences of complex heat flows for isothermally crystallized isotactic polypropylene (iPP) by the quasi-isothermal TMDSC. Regarding the quasi-isothermal melting processes as a kind of the single relaxation process, we analyze them by the Debye model. The resultant heat capacity of iPP is larger (about 11%) than usual thermodynamic heat capacity. We also found that the excess of the heat capacity, C p (excess), has non-monotonous temperature dependence. A simple model introducing some kinetic modes into amorphous producing after and during temperature modulation can reproduce the temperature dependence of C p (excess) very well.

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Abstract  

A pulse method was used to measure the thermal conductivity, specific heat capacity C p and thermal diffusivityξ of polycrystalline ZnIn2Se4 in the temperature range 300–600 K. The temperature dependence of λ, C p and ξ demonstrated a light decrease for this material in the temperature range 300–600 K, indicating that there is not a significant change in the structure in this temperature range; this was confirmed by DTA measurements. The results showed that the mechanism of heat transfer is due mainly to phonons; the contributions of electrons and dipoles are very small.

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Abstract  

In order to observe more directly the structural organization of water molecules around a non-polar molecule in an aqueous solution, heat capacity differences between two kinds of solutions (solution I and II) of quaternary ammonium salts were measured. In the solution I stable water structure was retained as much as possible and in the solution II water structure was destroyed either by heating to high temperatures or by irradiating with ultrasonic waves. It was found that the heat capacity differences ((Cp)II-(Cp)I) were slightly positive and its maximum values corresponded to 7-8 percent of the heat capacity of pure water itself.

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Abstract  

Thermodynamic properties of β-alanine in the temperature range 6.3–301 K were studied. No phase transitions were observed for the sample specially prepared to contain no solvent inclusions. At 298.15 K the calorimetric entropy and the difference in the enthalpy values are equal, respectively, to 126.6 JK−1 mol−1 and 19.220 Jmol−1. The C p (T) in the temperature range 6–16 K can be well described by Debye equation C p = AT 3. A comparison of the data on the entropies of glycine polymorphs and of β-alanine was used to show, that the empirical Parks–Huffman rule holds in the case of these compounds.

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Abstract  

Heat capacity C p(T) of dysprosium diboride is experimentally investigated at the temperatures of 5–300 K. On the dependence C p(T) smooth anomaly at the temperatures of 15–20 K and sharp anomalies at T m1=47.8 K and T m2=178.8 K are revealed. Anomaly at T m1 is caused, obviously, by ferromagnetic phase transition in DyB2. The lattice contribution to DyB2 heat capacity is determined by comparison with heat capacity of non-magnetic YB2. The estimation of Schottky contribution to DyB2 heat capacity is made, the scheme of splitting of the ground state of Dy3+ ion is offered.

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Since genetic recombination is a major factor in the evolution of the cytopathogenic (cp) bovine viral diarrhoea virus (BVDV) biotypes, in this study the cytopathogenicity markers were investigated in the genomes of two cp BVDV strains recently isolated from mucosal disease (MD) cases in Hungary. In the genome of strain H4956, a Jiv-like insertion was found similar to those described in reference strain NADL and in other BVDV 1, BVDV 2 and border disease virus (BDV) strains. The 133 amino acid Jiv-like sequence is inserted at nucleotide position 4984 (amino acid position 1533), 9 nucleotides upstream of that of strain NADL. The insertion showed 96% amino acid sequence identity with the cellular Jiv protein. In the genome of cp BVDV strain H115/PCR, an ubiquitin-containing duplication was found. The duplicated sequence started at nucleotide position 7978 (amino acid 2531) in the NS4B gene. The duplication contained a complete ubiquitin monomer of 76 amino acids and the complete NS3 gene starting at nucleotide position 5153 (amino acid 1589), which corresponds to the first N-terminal amino acid of NS3. The duplication was located further downstream of the known ubiquitin-containing genomic regions of cp BVDV strains, and it consisted of the shortest inserted nucleotide sequence. The insertions and duplication of strains H4956 and H115/PCR further confirmed that recombinations occurring at positions A and B are the most common mechanisms leading to the development of BVDV cytopathogenicity.

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