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Phase diagrams of perhydrotriphenylene and aromatic compounds

I. Trans stylbene and 4H-cyclopenta[2,1-b∶3,4-b′] dithiophene

Journal of Thermal Analysis and Calorimetry
Authors: G. Di Silvestro, Cui Ming Yuan, A. Terragni, Elisabetta Brenna, and Manuela Gilberti

Perhydrotriphenylene (PHTP) forms channel-like adducts with molecules of different size and molecular weight. In the crystal structure of the adduct the included long sequences of molecules are separated from each other by the channel walls. The optical properties of the included molecules differ from those of the bulk molecules. The phase diagram of mixtures of PHTP and trans stylbene and 4H-cyclopenta [2,1-b∶3,4-b′] dithiophene (CPDT) were determined by DSC experiments. Ideality in the liquid phase was observed only in the PHTP/CPDT system.

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Journal of Thermal Analysis and Calorimetry
Authors: K. B. Povarova, A. G. Padalko, A. A. Drozdov, N. K. Kasanskaya, N. L. Korenovskii, O. A. Skachkov, A. N. Veselov, A. E. Morozov, and I. O. Bannykh

Summary Thermostable high-temperature structural alloys based on the refractory (melting temperature T m=2060°C) RuAl intermetallic (IM) with an ordered B2 crystal structure (CsCl type) are developed. This IM surpass other aluminides (NiAl, TiAl and Ni3Al) used as the base for the development of high-temperature alloys and matrices of high-temperature composites (CM) intended for hot parts of supersonic engines, which serve at the temperatures exceeding operation temperatures of modern nickel-base superalloys. The differential barothermal analysis was used to develop the basic technological process of barothermal reaction sintering to produce near-net shape billets from RuAl-based structural materials.

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Effects of fission (fragment) damage on the magnetic properties were investigated for some uranium compounds with NaCl-type crystal structure, such as uranium monocarbide (UC, paramagnetic) monophosphide (UP, antiferro) and monosulfide (US, ferro). The induced changes in the magnetic properties due to the fission damage were much pronounced in the magnetically ordered state. A shift of the magnetic transition point (either the Neel (TN) and Curie (TC) temperature) was observed, together with the changes of the magnetic parameters. In some cases, a new magnetically ordered phase was revealed by the fission damage even at room temperature irradiation.

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The Mössbauer parameters were determined on a series of catalyst mixtures of iron and zinc oxides with variable quantities of zinc. From these results, a change in the crystal structure of the iron oxide when introducing zinc into the samples was observed. The corundum structure of the -Fe2O3 phase was transformed into the spinel type of zinc ferrite when zinc oxide was present in any quantity. By means of these parameters a strong electronic interaction between the zinc ferrite and the zinc oxide present in excess was evident. The catalysts were analyzed using X-ray fluorescence /XRF/ and X-ray diffraction /XRD/.

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Eugenol is an allyl chain-substituted guaiacol in the biosynthesized phenylpropanoid compound class derived from Syzygium aromaticum L. and widely used in folk medicine. Nonetheless, its pharmacological use is limited by some problems, such as instability when exposed to light and high temperature. In order to enhance stability, the eugenol molecule was structurally modified, resulting in eugenyl acetate. The eugenyl acetate’s thermal behavior and crystal structure was then characterized by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) and compared to a commercial sample.

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New lanthanoid-iron complexes having phenanthlorine as the chelating ligand were synthesized and characterized by151Eu- and57Fe-Mössbauer spectroscopy. The temperature dependence of the area intensity of Mössbauer lines of europium complexes (single crystals) has been correlated to the state of molecular association in the solid state. The crystal structure of europium complex, {[Eu(phen)2(H2O)2][(μ-NC)2 Fe(CN)4]·2phen]}x was determined by X-ray crystal analysis. This complex consists of one-dimensional zig-zag chain structure.

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A lunar olivin monocrystal (Mg, Fe)2SiO4 of about 0.011 mg was analyzed by neutron activation analysis (NAA) and by X-ray crystal structure research (XRCSR). Both methods demonstrated the presence of small concentrations of Sc, Cr, Mn, and Co, the quantitative results for these elements are in the range of about 102 to 103 ppm. Mg was analysed only by XRCSR. Good agreement between both methods was found for the concentrations of Fe and Na, the Fe excess by NAA can be explained with included impurities.

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The calorimetric (DSC) and derivative thermogravimetric (DTG) measurements for crystalline mono- and hemiphosphates of cytidine and deoxycytidine have been performed. The results for four examined salts confirm the influence of presence (or absence) of 2'OH group in ribose ring on stability (or lability) of the crystal structure of examined salts.

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Lead(II) 2,2'-bipyridine hexachloroplumba tetetrahydrate was synthesized and investigated by DTA, TG and DTG. IR spectroscopy and other methods enabled the identification of some of the decomposition products. Comparative studies on the corresponding chlorides: [Pb(bipy)]Cl2 and [Pb(bipy)3]Cl2, which can be considered as precursors of the hexachloroplumbate, were also undertaken. X-ray measurements enabled the tentative determination of the crystal structure of [Pb(bipy)]Cl2. Hexachloroplumbate decomposes with the liberation of chlorine, water and organic ligands, and the process is accompanied by the simultaneous transition of Pb(IV)→Pb(II). Chlorides release only ligands upon heating. Residues comprised always PbCl2.

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The original investigations of ferrocene mesogens with general formula Fe(C5H4C(CH3)=N–N=CHC6H4COOC6H4OCnH2n+1J2 and their solutions in liquid crystalline solvents by Mossbauer spectroscopy as well as by calorimetry, thermomicroscopic and X-ray analysis are discussed. The data on electron, molecular and crystal structures, polymorphism and dynamical properties of these substences and frozen solutions are presented. For ferrocene mesogens and their solutions, aligned by external magnetic field, the values of order parameter and inter- and intramolecular contributions to the nuclear vibrational anisotropy of central metal atom are estimated.

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