Femtosecond intermolecular electron transfer in condensed systems

We have investigated the ultrafast intermolecular electron transfer (ET) from an electron-donating solvent (aniline (AN) or N, N-dimethylaniline (DMA)) to an excited dye molecule (oxazines (Nile blue and oxazine 1) or coumarins). A non-exponential time dependence was observed in AN and can be explained by solvent reorientation and nuclear motion of the reactants. However, in DMA, a single exponential process was observed for Nile blue (160 fs) and oxazine 1 (280 fs), which can be explained by assuming that the rate of ET is limited mainly by ultrafast nuclear motion. A clear substituent effect on intermolecular ET was observed for the 7-aminocoumarins. When the alkyl chain on the 7-amino group is extended and a hexagonal ring with the benzene moiety is formed, the rate of ET is reduced by three orders of magnitude. This effect can be explained by a change in the free energy difference of the reaction and by the vibrational motion of the amino group.     

Codimension Two PL Embeddings of Spheres with Nonstandard Regular Neighborhoods

For a given polyhedron K(?)M,the notation RM(K)denotes a regular neigh- borhood of K in M.The authors study the following problem:find all pairs(m,k) such that if K is a compact k-polyhedron and M a PL m-manifold,then R_M(f(K))≌R_M(g(K))for each two homotopic PL embeddings f,g:K→M.It is proved that R_S~(k 2)(S~k)(?)S~k×D~2 for each k(?)2 and some PL sphere S~k(?)S~(k 2)(even for any PL sphere S~k(?)S~(K 2)having an isolated non-locally flat point with the singularity S~(k-1)(?) S~(k 1)such thatπ_1(S~(k 1)-S~(k-1))(?)Z).     

Vertical displacement of immiscible fluids from heterogeneous formations

The modified phase permeability model [1, 2] is extended to the case of vertical displacement with allowance for the force of gravity. It is assumed that in connection with vertical displacement a thicker dometype formation may be regarded as a stream tube of variable cross section. An exact solution of the one-dimensional displacement problem is constructed. It is shown that in vertical displacement from heterogeneous formations the gravity forces stabilize the displacement, so that at low velocities it approaches displacement of the pure piston type. It is established that a decrease in the injection and extraction rates leads to an increase in hydrocarbon output, and an increase in formation pressure to a fall in output.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 91–97, March–April, 1991.The authors wish to thank K. S. Basniev and A. K. Kurbanov for formulating the problem and taking an interest in the work.     

Coupled instability of compressed thin-walled rods with a closed transverse cross section

Dnepropetrovsk Civil Engineering Institute, Ukraine. Translated from Prikladnaya Mekhanika, Vol. 29, No. 2, pp. 62–68, February, 1993.