Analysis of degradation products by thermal volatilization analysis at subambient temperatures

In the subambient thermal volatilization analysis (TVA) technique, degradation products initially at ?196°C are allowed to warm up to ambient temperature in a controlled manner under vacuum conditions, and volatilization from the sample tube to a trap at ?196°C is monitored by means of a Pirani gauge. The technique is discussed in relation to earlier TVA work in which volatilization from a heated polymer sample was followed. Design and operation of a subambient TVA system are described, and examples of the application of the technique to the study of the degradation products of seven polymers are considered.     

Electrocatalysis by foreign metal monolayers: Oxidation of formic acid on platinum

It was demonstrated that some foreign metal monolayers formed by underpotential deposition have pronounced catalytic effects on the oxidation of formic acid on platinum. The explanation of these effects was sought within the framewor of existing data on the formic acid oxidation and the underpotential deposition. It was found that the catalytic effect of foreign metal monolayers originates in the decrease of hydrogen adsorption thus preventing the formation of the main poisoning species COH. At the same time these experiments confirm the previously postulated mechanism of formation of the poisoning species involving adsorbed hydrogen.     

Activation Analysis Methods and Applications

Summary INAA was applied for searching more effective biosorbents for U and Ag among 9 and 47 strains of actinomyces, respectively. Biomasses of strains were tested for the Ag and U sorption capacity from model solution, containing 50 mg/l Ag ions and from technological solution of U-production, containing 7.11 mg/l U ions. The U and Ag samples were irradiated for 5 hours and 20 hours, respectively, at a neutron flux density of 5.3 ^. 10¹³ n ^. cm^-2 ^. s^-1. The Ag content was calculated from the gamma-line of radionuclide ^110mAg (T_1/2 = 250.4d, E_γ= 657.7keV). The U content was calculated from the gamma-lines (228.2 keV, 277.8 keV) of radionuclide ²³⁹Np (T_1/2 = 2.35 d). The error of U and Ag determination (relative standard deviation) was 2-3%.     

Structure of ammonium salts of 2-oxy-1,4-butylene-and 2-oxy-1,5-amylenephosphoric acids

The structures of dioxaphosphepane (I) and dioxaphosphecane (II) salts prepared by hydrolysis of the corresponding bicyclophosphates have been compared. In both cases, hydrolysis occurs with breaking of the P–O bond of the fragment at the secondary carbon atom of bicyclophosphate. In phosphocycles I and II, the endocyclic bond angles O–P–O are 104.2 and 104.9°, and the exocyclic ones are 117.7 and 118.6°, respectively. Conformations of the anions in I and II differ substantially: for I it is a twist conformation^C1T_C4, and for II a distorted armchair. The data obtained are compared with those found earlier for similar molecules.Moscow State Pedagogical University. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 4, pp. 154–160, July–August, 1993.Translated by T. Yudanova