Low mass πN enhancement in inelastic αp interaction

Evidence for an enhancement in the isospin $\text{I =}\text{1}\text{2}\text{π}\text{N}$ system at M = 1130 MeV/c² (Γ = 80 MeV/c²) has been found in the reaction αp → αx at an incident α-momentum of 4.00 and 5.08 GeV/c. A strong t-dependence of the cross section and a mass-slope correlation are seen as the main features of the data.     

Comment on the concentration and temperature dependences of the translational diffusion coefficient of flexible-coil macromolecules in solution: Poly(2-vinyl pyridine) in tetrahydrofuran

Concentration-dependence coefficients k_D^? of the mutual diffusion coefficient of poly(2-vinyl pyridine) in tetrahydrofuran in the temperature range 15–55°C are compared with predictions of recent theories of macromolecular diffusion. In this temperature range a change in local conformation of the polymer occurs. The accompanying changes in chain solvation and coil hydrodynamics result in a sizable decrease in the hydrodynamic interaction parameter X defined by Akcasu. The formulation of theory appropriate for comparison with frame-indifferent experimental diffusivities is discussed. We find that current theories predict qualitatively, but not quantitatively, the change in temperature dependence of k_D^? that occurs at the conformational transition. The discrepancies closely parallel those reported in recent independent comparisons of theoretical k_D^? versus experimental data for flexible-coil molecules. No theory can adequately predict k_D^? over a wide range of X.     

On the determination of factor systems of PUA-representations

A method is developed to obtain a complete set of inequivalent factor systems of PUA-representations of a group with a subgroup of index two from the factor systems of this subgroup.     

Circular polarization and γ-γ angular correlation measurements in the 39K(n, γ)40K reaction

Circular polarization measurements of the γ-radiation from polarized neutron capture combined with γ-γ angular correlation measurements in the ³⁹K(n,γ)⁴⁰K reaction lead to J^π = 2^? assignments to the E_x = 0.80, 2.05 and 2.42 MeV states of ⁴⁰K, and to spin restrictions for the states at E_x = 2.10, 3.44 and 4.25 MeV. Multipole mixing ratios for the γ-rays which de-excite these levels have been determined.     

Long range phenomena—XIV: 1H-{1H} indor spectra and relative signs of coupling constants of some oxirane derivatives with adjacent methylene groups

PMR parameters of some methylene substituted oxiranes are obtained from INDOR experiments on the ABXMN spin systems. Compounds investigated include safrol- and bromosafrol epoxide and β-phenoxypropylene oxide. For the latter compound all the relative signs (except for some long range couplings) were obtained and certain of these are in contradiction with those reported ² in β-chloropropylene oxide. ‘Non-classical’ long range coupling is also noted and differs in pathway from that reported previously.².     

First structural characterization of a protactinium(V) single oxo bond in aqueous media

The present work describes the first structural studies of protactinium(V) in sulfuric and hydrofluoric acid media using X-ray absorption spectroscopy. The results show unambiguously the absence of the trans-dioxo bond that characterizes the other early actinide elements such as U and Np. In concentrated sulfuric acid (13 M), Pa(V) is proved to exhibit a single oxo bond as postulated in the literature for species in more dilute media. In a 0.5 M HF medium, XANES and EXAFS spectra indicate the absence of any oxo bond: Pa(V) exists in the form of a pure fluoro complex.     

Thin-layer chromatography of metal ions on bonded stationary phases

Summary The separation of iron, copper, nickel, and zinc by thin-layer chromatography was studied. Eight bonded-phase silica substrates and twenty-nine solvent systems were investigated. Solutions of 1% diphenylcarbazide in ethanol and 1% K₄Fe(CN)₆ in water were used to detect the metal ions. The best separation was obtained with an immobilized trifluoroacetylacetone substrate and 10% trifluoroacetylacetone in acetone mobile phase.     

Investigation of 28Si levels with the (α, γ) and (p, γ) reactions

Particle energies have been measured for resonances in the ²⁷Al(p, γ)²⁸Si and ²⁴Mg(α, γ)²⁸Si reactions with an accuracy of 0.5 × 10^?4 and 1 × 10^?4, respectively. The E_p = 991.88 ± 0.04 keV²⁷Al(p, γ)²⁸Si resonance served as calibration point. From these data the Q-value of the reaction ²⁷Al(p, α)²⁴Mg has been determined as 1600.14 ± 0.21 keV. Excitation energies of ²⁸Si levels have been measured with the ²⁷Al(p, γ)²⁸Si reaction; the reaction energy is Q = 11584.5 ± 0.4 keV.Of 33 resonances observed in the ²⁴Mg(α, γ)²⁸Si reaction (E_α = 1.5–3.8 MeV), energies, strengths and γ-ray decay have been measured; five of these resonances had not been reported previously. The γ-ray angular distribution measurements at three resonances yield the resonance J^π values and the mixing ratios of the strongest transitions involved in the decay. The 10.38 MeV level has J^π = 3⁺, T = 1. The arguments on which T-assignments can be based are critically reviewed. These arguments are used to assign T = 1 character to ¹⁹ states of ²⁸Si.