Bases of free metabelian and transmetabelian groups

A definition of the basis of a group written in additive form is given based on P. Hall's collecting process. The bases of free rank 2 groups of the following three types are found: metabelian, transmetabelian of the first type (with an Abelian third term in the lower central series), and transmetabelian of the second type (the nilpotency class of whose derived group is equal to two).Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademiya Nauk SSSR, Vol. 191, pp. 126–139, 1991.     

Comparative kinetics of phospholipase A2 action on liposomes and monolayers of phosphatidylcholine spread at the air-water interface

A detailed kinetic model describing the surface transformation of spread liposomes along with their enzymatic hydrolysis was developed. The model was applied to the hydrolysis of the long-chain phosphatidylcholine generating reaction products which remain at the interface and to medium-chain substrates from which the products desorb rapidly into the bulk phase. The overall kinetic constants of the hydrolysis in liposomal systems were compared with those obtained with monolayers under barostatic conditions. The values of the interfacial Michaelis-Menten constant were estimated.     

Application of129Xe 2D-EXSY NMR to intra- and interparticle exchange in zeolites

2D-EXSY NMR methods were used to explore diffusion between different domains in zeolites on two very different length scales. Measurements were made on xenon-containing samples consisting of a mixture of NaX and NaY zeolite particles which give distinct resonance lines. The cross peaks observed were interpreted in terms of interparticle exchange, and exchange rates were measured as a function of particle size. This kind of experiment with a length scale of microns to mm should be useful in model studies of diffusion in packed catalyst beds. Measurements also were made to study exchange on a much smaller length scale between the main-channel and side-pocket sites in samples of microcrystalline Na-mordenite. Exchange rates and site occupancies were measured as a function of temperature, yielding activation energies for xenon desorption and intersite diffusion. Also, information was obtained on the distribution of inequivalent side-pocket sites which leads to the large xenon NMR linewidths for this type of site.     

On the correctness of a linear closure of set of recognition algorithms of the decision tree type

A recognition operator of the decision tree type is proposed in this paper that is used for the canonical representation of a recognition algorithm, and a theorem is proved about the correctness of the linear closure of a class of incorrect recognition algorithms based on the construction of decision trees.Translated from Dinamicheskie Sistemy, No. 5, pp. 91–94, 1986.     

Measurement of the spin and temperature dependence of ddµ molecule formation rate in solid and liquid deuterium

The ddµ molecule formation rate is experimentally measured for the two hyperfine states of the dµ-atom in the temperature range of 5–30 K. Results are consistent with a preliminary measurement by the TRIUMF group and contradict theoretical predictions. The work has been performed on the JINR phasotron (Dubna).     

g-factor anisotropy for donor-bound electrons at all magnetic fields

Summary A theory of theg-factor for electrons bound to donors in zincblende semiconductors is presented for all magnetic fields. Simple analytical expressions are obtained for weak, intermediate and high magnetic-field intensities. A comparison between theory and the experimental result in the case of InSb is made.     

The Modified Group Expansions for Construction of Solutions to the BBGKY Hierarchy

A solution to the BBGKY hierarchy for nonequilibrium distribution functions is obtained within modified boundary conditions. The boundary conditions take into account explicitly both the nonequilibrium one-particle distribution function as well as local conservation laws. As a result, modified group expansions are proposed. On the basis of these expansions, a generalized kinetic equation for hard spheres and a generalized Bogolubov–Lenard–Balescu kinetic equation for a dense electron gas are derived within the polarization approximation.