Search Results

You are looking at 1 - 10 of 13 items for

  • Author or Editor: V. Lazarev x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

On behalf of a case study of articles on bibliometric selection and ranking the variance in terminology of the properties of journals is shown: the same properties are called in various manners, while one and the same terms have different meanings. Similar inconsistencies are found in the terms denoting readers' activities which are studied in bibliometrics for the assessment of the use of periodicals. The author concludes that there are actually only two properties of periodicals that are quantitatively assessed, viz. productivity, and value. Their definitions are suggested for terminology standardization of general properties of journals and of readers' activities.

Restricted access

Abstract  

The termal stabilities of several families of high-T c superconductors (HTSC), as well as the dependence of phase transitions on temperature and stoichiometry, have been studied by X-ray diffraction, DTA, TG and DSC. Experimental results are discussed in the context of decomposition models.

Restricted access

DSC and vapour pressure measurements are presented on some Be, Al and Cr complexes with 2,4-pentanedione tetramethyl-3,5-heptanedione, 1,1,1-trifluoro-2,4-pentanedione and hexafluoro-2,4-pentanedione. Thermodynamic functions are given for the sublimation, vaporization and melting processes of the substances.

Restricted access

The thermal decompositions of a series of complex copper oxides and some other transition metal oxides were studied by simultaneous TG-DTA. The oxygen stoichiometry was determined by thermogravimetry. For the compound YBa2Cu3O7−x, the electrical properties and some structural peculiarities depend on the oxygen content.

Restricted access

The thermal decompositions of the acetates of Pr, Nd, Sm, Gd and Ho have been investigated using thermogravimetry and differential thermal analysis, together with infrared spectroscopy and X-ray diffraction. The thermal decompositions of the acetates of the rare earth elements exhibit several stages, depending upon both the number of crystal water molecules in the acetates and the rare earth element behaviour. Experiments with the benzoates and abietates of Pr, Nd, Sm, Gd and Ho indicate some correlations in the thermal decompositions of carboxylates of the rare earth elements.

Restricted access

Low temperature heat capacity of ammonium, rubidium and cesium perbromates has been studied by method of adiabatic calorimetry. Anomaly of the heat capacity of cesium perbromate has been found, which corresponds to a structural phase transition. The separation of heat capacity into components has been carried out by the additive scheme. The torsion oscillation of BrO4 anions in solid perbromates at low temperatures has been found. Ammonium ions retardedly rotate aroundC 2 axes in the crystal lattice of NH4BrO4.

Restricted access

Several commercial and laboratory-synthesized specimens of silica gel have been studied, using thermogravimetry. Two forms of adsorbed water have been found: the first form, which evaporates in the temperature range 100–200°, is polymolecular water layer in open pores and loosely-bonded molecules on the surface and in the bulk of the globules; the second form, which evaporates in the temperature range 200–700°, comprises water molecules hydrogen-bonded to silanol groups, and evidently coordinated to silicon atoms. The dehydration heat of the first form, determined from the DTA curves, depends on the ratio of the two forms, and varies from 3.7±0.6 kcal/mole H2O for coarse-grain silica gel produced at pH=7 to 12±1 kcal/mole H2O for fine-grain silica gel of commercial “chromatography” grade.

Restricted access