Opis: The study of two different methods of obtaining chiral alcohols is proposed herein. The requirement of the relatively new paradigm of green chemistry associated with clean technologies such as biocatalysis or non-conventional solvents, dense gases, was focused at. Indeed, the two methods of production of chiral alcohols were: - the conversion of acetophenone into (R)-1-phenylethanol in dense gases catalysed by Lactobacillus brevis alcohol dehydrogenase and its coenzyme, NADP/H; - the resolution of (±)-trans-1,2-cyclohexanediol by cocrystal formation with tartaric acid followed by supercritical extraction. In both cases high enantiopurities were achieved (ee>99%).Najdeno v: ključnih besedahPovzetek najdenega: ...exanediol, tartaric acid, cocrystal, supercritical carbon dioxide, extraction, X-ray diffraction, differential scanning calorimetry...Ključne besede: High-pressure technologies, enantiomers, green chemistry, R-1-phenylethanol, Lactobacillus brevis, alcohol dehydrogenase, NADP, liquid propane, enzyme deactivation, resolution, trans-1, 2-cyclohexanediol, tartaric acid, cocrystal, supercritical carbon dioxide, extraction, X-ray diffraction, differential scanning calorimetryObjavljeno: 02.02.2011; Ogledov: 928; Prenosov: 20 Polno besedilo (6,25 MB)
Opis: A survey of the subsolidus phase equilibria in the system Li2O-Nd2O3-Fe2O3 wasmade at subsolidus temperatures in the range 1000-1050 °C. A ternary phase was identified. The phase is centered on Li5Nd4FeO10, with a cubic lattice a =11.9494 A. The compound melts incongruently at 1105 °C. The magnetic susceptibility was measured in the temperature range 4-300 K. The compound is paramagnetic in the temperature range 150-300 K and follows the Curie-Weiss law. At about TN = 10 K, a long-range magnetic ordering is observed.Najdeno v: ključnih besedahPovzetek najdenega: ...ithium ferrites, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, magnetic properties, phase equilibrium...Ključne besede: lithium ferrites, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, magnetic properties, phase equilibriumObjavljeno: 01.06.2012; Ogledov: 144; Prenosov: 0 Polno besedilo (0,00 KB)
Opis: The ▫$Li_1.746Nd_4.494FeO_9.493$▫ (LNF) ternary phase, located in the ▫$Li_2O$▫-rich part of the ▫$Li_2O-Nd_2O_3-Fe_2O_3$▫ system, crystallizes with a cubic unit cell of dimension and the space group Im3m. Refinement on F resulted in R=1.9%. The structure is comprised of a network of corners, edges and faces sharing the coordination polyhedra of neodymium. In between this skeleton the regular octahedra of oxygen-coordinated iron and trigonal prisms of lithium are located. The Mössbauer spectra revealed the presence of ▫$Fe^3+$▫, ▫$Fe^4+$▫ and ▫$Fe^5+$▫ ions distributed on two symmetry-independent lattice positions.Najdeno v: ključnih besedahPovzetek najdenega: ...crystal structure, ternary compounds, single-crystal X-ray diffraction, Mössbauer spectroscopy, iron oxidation state, kristalna...Ključne besede: crystal structure, ternary compounds, single-crystal X-ray diffraction, Mössbauer spectroscopy, iron oxidation state, kristalna struktura, ternarne spojine, rentgenska difrakcija, Mössbauerjeva spektroskopija, rentgenska strukturna analizaObjavljeno: 01.06.2012; Ogledov: 136; Prenosov: 2 Polno besedilo (0,00 KB)
Opis: A new hydroxylammonium compound (NH3OH)2GeF6, has been synthesized by the addition of solid NH3OHF to a solution of GeO2 dissolved in 20% HF. The compound was characterized by chemical analysis and X-ray powder diffraction, the thermal decomposition was studied by thermal analysis and mass spectrometry. (NH3OH)2GeF6 crystallizes monoclinic. Two endothermic and two exothermic peaks have been observed on the DSC curve, the decomposition product at 500 °C is GeO2.Najdeno v: ključnih besedahPovzetek najdenega: ...compound was characterized by chemical analysis and X-ray powder diffraction, the thermal decomposition was studied...Ključne besede: inorganic chemistry, synthesis, characterisation, hydroxylammonium fluorogermanates, x-ray powder diffraction, mass spectroscopy, thermal analysisObjavljeno: 01.06.2012; Ogledov: 136; Prenosov: 0 Polno besedilo (0,00 KB)
