Chemical polarization of nuclei

Conclusions The reaction of 2,6-di-tert-butyl-1,4-benzoquinonediazide with primary aliphatic amines leads to the formation of intermediate unstable triazenes which, in turn, break down through a radical mechanism to form 2,6-di-tert-butylphenol and 2,6-di-tert-butyl-p-benzoquinone, the final reaction products.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 771–775, April, 1977.     

Interactions of lanthanide atoms: Comparative ab initio study of YbHe,Yb<Subscript> 2</Subscript> and TmHe,TmYb potentials

The results of high-level ab initio calculations are reported for the interatomic potentials describing YbHe, Yb₂, TmHe and TmYb van der Waals interactions. It is found that the interaction properties of Tm and Yb are very similar and the interaction anisotropy in the TmHe and TmYb complexes is very small. We analyze the long-range behavior of the isotropic and anisotropic interaction potentials and discuss some implications for cold and ultracold atomic collisions of the lanthanide atoms.     

Transition to Chaos in the Floating Half Zone Convection

The transition process from steady convection to chaos is experimentally studied in thermocapillary convections of floating half zone. The onset of temperature oscillations in the liquid bridge of floating half zone and further transitions of the temporal convective behaviour are detected by measuring the temperature in the liquid bridge. The fast Fourier transform reveals the frequency and amplitude characteristics of the flow transition. The experimental results indicate the existence of a sequence of period-doubling bifurcations that culminate in chaos. The measured Feigenbaum numbers are δ2 =4.69 and δ4 = 4.6, which are comparable with the theoretical asymptotic value δ=4.669.     

Photooxidation of water by molecular oxygen: isotope exchange

The phototransfer of isotopic nuclei from water molecules to oxygen as evidence for the direct photooxidation of water by molecular oxygen was detected experimentally. The mechanism and its ecochemical consequences and significance are presented.     

New versatile mechanism of enzymatic synthesis of adenosine triphosphate: theoretical foundation and experimental control

The energies of electron transfer between pyrophosphate metal complexes and hydrated metal complexes, which is the key reaction that models the radical ion mechanism of adenosine triphosphate (ATP) synthesis, were calculated. A threshold dependence of the energy on the number of water molecules n in the ion hydration sphere was established: for n < 4 the reaction is exothermic, while for n ≥ 4 it is endothermic. The switching of the energy regime accounts for the fact that ATP is synthesized only in molecular machines, enzymes, rather than in homogeneous aqueous solutions. It was predicted theoretically that the radical ion ATP synthesis may be catalyzed by not only magnesium ions as in living cells but also by calcium, zinc, barium, cadmium, and tin ions. This prediction was experimentally confirmed by the discovery of the magnetic isotope effect in the calcium- and zinc-catalyzed ATP synthesis by creatine kinase. The efficiency of ATP synthesis in the presence of ions with magnetic nuclei ⁴³Ca and ⁶⁷Zn is almost twice as high as that in the presence of the same ions with nonmagnetic nuclei ⁴⁰Ca and ⁶⁴Zn.