Cross sections for photodisintegration of 32S to excited residual states

Cross sections and integrated cross sections for photodisintegration of ³²S to specific residual states in ³¹P and ³¹S have been measured. Comparison with spectroscopic factors for nucleon pickup reactions on ³²S leading to the same residual states are made. It is concluded that the creation and decay of the dipole state in ³²S is predominantly a single-nucleon interaction.     

Hydrogen-bonding effects,electrostatic potential,and the antitumor activity of flavone acetic acid and related compounds. I. Ab initio studies on the first stable conformations

Ab initio investigations have been carried out to account for the antitumor activity of flavone acetic acid (FAA) and related compounds. The hydrogen-bonding conformation was chosen for all the compounds and obtained through a restricted geometry optimization with the 3-21G basis set. Three key regions in the molecular electrostatic potential isosurfaces [V( r ) ～ ?0.015 au] are found to be involved in the activity. Region 1 is the most important. Its existence implies the activity and its size determines the strength of the activity. Region 2 is another factor which can change the strength of the activity. Region 3 corresponds to the hydrogen-bonding effects which have been analyzed in detail, but its role is still not clear. Finally, basis-set effects on the molecular electrostatic potential have been briefly discussed. © 1995 John Wiley & Sons, Inc.     

Ab initio calculations relevant to the mechanism of chemical carcinogenesis by N-nitrosamines. VIII. Effects of hydration on various reactions involved in the formation and metabolism of N-nitrosamines

A number of important reactions involved in the formation and metabolism of N-nitrosamines have been studied using a modified reaction field method which treats the solute quantum mechanically and the solvent as a polarized dielectric.     

Photoproton and photo-α cross sections of 19F to excited residual states

Cross sections and integrated cross sections for photodisintegration of ¹⁹F to excited residual states following emission of protons, neutrons and α-particles have been measured. The size of the photo-α cross sections appear to be too large to be explained by a semidirect reaction mechanism.     

An ab initio investigation of the geometry,bonding and coupling constants of BF2

Comparative calculations, using five different basis sets of contracted Gaussian functions, of the geometry, bonding and hyperfine coupling constants of BF₂ are reported. The best calculation, using a near Hartree-Fock atomic basis, predicts a bond angle of 120° and a bond length of 2.50 a.u. (=1.32 Å) for the X ² A ₁ ground state. The geometries of three low-lying excited states are also presented.     

Cellular-indecomposable subnormal operators

A bounded operator T is cellular-indecomposable if LnM{0} whenever L and M are any two nonzero invariant subspaces for T. We show that any such subnormal operator has a cyclic normal extension and is unitarily equivalent modulo the compact operators to an analytic Toeplitz operator whose symbol is a weak-star generator of H.Dedicated to the memory of James P. WilliamsThis work was supported in part by a grant from the National Science Foundation.