Vapour phase motion in cryogenic systems containing superheated and subcooled liquids

The development of vent pipelines, and venting storage tanks for cryogenic liquids requires the knowledge of the law of motion as well as regularities of vapour content variation in the liquid and heat dissipation by the vapour phase. This is a theoretical study of the effect of superheating (subcooling) of the liquid, relative acceleration and reduced pressure upon the size and velocity of noninteracting vapour bubbles, moving in the liquid, and upon their resistance and heat transfer coefficients.     

Calculation of the helium thermodynamic state in rotating cryostats

The present paper contains basic essential data for the design of rotating cryostats. The effect of the filling factor, angular velocity of rotation, reduced temperature at the axis of rotation and the method of helium supply to a rotating cryostat on temperature, pressure and density distribution is discussed. The maximum sub-cooling and distance from the axis of rotation at which the critical pressure is reached is studied theoretically. For vapour phase quasi-saturation there is a good agreement between the calculated data on temperature distribution and the experimental results available.     

Properties and structure of (As2Se3)1 ? z (SnSe2) z ? x (Tl2Se) x and (As2Se3)1 ? z (SnSe) z ? x (Tl2Se) x glasses

Tin is stabilized in the bivalent and tetravalent states in the structure of (As₂Se₃)_{1 − z} (SnSe₂) _{z − x} (Tl₂Se) _x and (As₂Se₃)_{1 − z} (SnSe) _{z − x} (Tl₂Se) _x glasses. The presence of bivalent tin in the structural network of a glass does not give rise to extrinsic conductivity. Dependences of density, microhardness, and the glass-transition temperature on the composition of the glasses are interpreted using a model according to which the structure of the glasses is composed of structural units that correspond to As₂Se₃, AsSe, TlAsSe₂, Tl₂Se, SnSe, and SnSe₂ compounds. Original Russian Text ? G.A. Bordovsky, A.V. Marchenko, E I. Terukov, P.P. Seregin, T.V. Likhodeeva, 2008, published in Fizika i Tekhnika Poluprovodnikov, 2008, Vol. 42, No. 11, pp. 1353–1356.     

Impurity tin atoms in glassy As x S1 − x and As x Se1 − x

¹¹⁹Sn Mössbauer emission spectroscopy data demonstrate that the impurity tin atoms resulting from the radioactive decay of the ¹¹⁹Sb isotope in the structure of glassy As _x S_{1 ? x} and As _x Se_{1 ? x} alloys reside on the arsenic site and act as two-electron amphoteric centers with a negative correlation energy: tetravalent six-coordinate tin acts as a singly ionized donor, and divalent three-coordinate tin, as a singly ionized acceptor.     

Determination of forms of element occurrence in samples of vanadium slag and slime

Complex research of technogenic raw material samples is carried out. Using the methods of X-ray diffraction and X-ray fluorescence analysis, the chemical and phase compositions of roasted vanadium slag and slime are established. The compounds of the base elements are extracted sequentially according to a three-stage scheme recommended by the European Commission. Their low mobility is recorded. Vanadium and manganese compounds possess higher mobility in the slag than in the slime. Iron and chromium form solid oxides and silicates that are disintegrated only under the action of HNO₃. The methods of microwave plasma atomic emission spectrometry (MP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) are used to determine the gross contents of V, Mn, Fe, Cr, Zn, Ni, Ba, Sr, Rb, Y, Ga, Ge, Mo, La, and Ce in the samples of slag and slime. It is shown that the total concentration of V, Mn, and Cr considerably exceeds the values of the maximum allowable concentrations (MAC) of these elements established for soils, objects with a sample base that is no less complex. Possible leaching of the forms of elements from solid samples of vanadium slime and slag with 0.1 M Na₂CO₃ solution and the mobile phase for reversed-phase high performance liquid chromatography (RP HPLC) is studied. Mostly, vanadium compounds are extracted under these conditions. Manganese compounds are extracted by 1–10%. An inconsistency is found between the time of retention during the chromatographic separation of V and Fe forms in the model mixtures and solutions obtained after the samples of vanadium slag and slime have been chemically treated.