On Homotopes of Novikov Algebras

Given a unital associative commutative ring Φ containing $\frac{1}{2}$ , we consider a homotope of a Novikov algebra, i.e., an algebra $A_\varphi $ that is obtained from a Novikov algebra A by means of the derived operation $x \cdot y = xy\varphi $ on the Φ-module A, where the mapping ? satisfies the equality $xy\varphi = x(y\varphi )$ . We find conditions for a homotope of a Novikov algebra to be again a Novikov algebra.     

Steric retardation of SN2 reactions in the gas phase and solution

The gas-phase S(N)2 reactions of chloride with ethyl and neopentyl chlorides and their alpha-cyano derivatives have been explored with B3LYP, CBS-QB3, and PDDG/PM3 calculations. Calculations predict that the steric effect of the tert-butyl group raises the activation energy by about 6 kcal/mol relative to methyl in both cases. Solvent effects have been computed with QM/MM Monte Carlo simulations for DMSO, methanol, and water, as well as with a polarizable continuum model, CPCM. Solvents cause a large increase in the activation energies of these reactions but have a very small differential effect on the ethyl and neopentyl substrates and their cyano derivatives. The theoretical results contrast with previous conclusions that were based upon gas-phase rate measurements.     

Investigation of the fragmentation of 20Ne and 40Ar ions at the COMBAS setup

Properties of the COMBAS fragment separator are compared with respective properties of similar setups. Results of experiments aimed at obtaining products of one-proton-stripping reactions induced by a beam of ⁴⁰Ar ions with an energy of 35 MeV/A and two-neutron-stripping reactions induced by a beam of ²⁰Ne ions with an energy of 52 MeV/A are presented. A high resolution of the fragment separator in obtaining secondary neutron-rich ³⁹Cl and neutron-deficient ¹⁸Ne ion beams is demonstrated.     

Sodium Borohydride–Mediated Transesterification

In the presence of sodium borohydride, esters react with alcohols with formation of the corresponding esters. The reaction is sensitive to the solvent, structure of the ester, and is often concurrent with reduction. Thioesters containing an ester group can be selectively cleaved by the reagent. Both esters and thioesters attached to solid support are resistant toward sodium borohydride. The in situ prepared sodium tetraalkoxyborate is introduced as an efficient reagent and catalyst for transesterification.     

Dissipative processes in peripheral heavy ion collisions at Fermi energies

Peripheral heavy ion reactions are of interest for the production of new isotopes. In this contribution we present an investigation of reactions of light projectiles O and Ne on Be and Ta targets at Fermi energies in the framework of transport theory. Transport theory describes dissipative (deep-inelastic) processes, where considerable amounts of mass and energy are exchanged. The data, on the other hand, also seem to include a more direct component with small energy loss. We separate the two components on the basis of the velocity distribution and compare the dissipative component to the transport calculations. The primary fragments of the transport calculation still have considerable excitation energies. For the comparison with experiment we take into account the secondary evaporation in a statistical model. This improves the qualitative agreement with the data.