Use of the paramagnetic shift agent Eu(DPM)3 for studying the structure and stereochemistry of conferol and conferone

Summary A spectrophotometric method is proposed for determining the content of aspidin in a crystalline powder and in the rhizomes of the fernsDryopteris spinulosa (M),D. phegopteris (L.), andD. fragrans (L.) Schott.All-Union Scientific-Research Institute for Medicinal Plants. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 684–687, November–December, 1970.     

Thermochemistry of Compounds of the MI I(PUO6)2·nH2O Series

The standard enthalpies of formation of uranophosphates M^{I I}(PUO₆)₂·nH₂O (M^{I I} = Mn, Fe, Co, Ni, Cu, Zn, Cd) are determined. The standard enthalpies of the synthesis and dehydration of these compounds are calculated and analyzed.     

Variation in the rate of oxidation of trivalent cerium by bromate in the Belousov-Zhabotinskii reaction under the influence of a weak magnetic field and hydroquinone

It was established that during the simultaneous action of a weak magnetic field (H=40 A/m, f=0.03 Hz) and hydroquinone at a low concentration on the oxidation of trivalent cerium by bromate magnetic field effects are absent, although separately a magnetic field accelerates and hydroquinone retards the reaction. These results can serve as indirect evidence that the mechanism of the action of the weak magnetic field on this reaction is free-radical in nature.Translated from Teoreticheskaya i Éksperimental/naya Khimiya, Vol. 26, No. 5, pp. 624–627, September–October, 1990.The authors thank A. B. Rovinskii for useful discussion and critical remarks.     

Numerical analysis of isothermal space-charge relaxation in a dielectric with blocking electrodes

For a dielectric with blocking electrodes, the system of continuity and Poisson's equations is numerically solved in the nonsteady case. The distribution of the mobile-charge concentration and field inside an electrically neutral dielectric at various times, both after the potential is switched on and after the short-circuiting the latter. The time dependences of the isothermal polarization and depolarization currents are calculated. It is established, in particular, that these dependences for a dielectric with one type of mobile charge carrier are not approximated by an exponential.