Isotope shifts and hyperfine structure of natural dysprosium

Isotype shifts and hyperfine structure measurements for five transitions in natural dysprosium have been performed using a CW tunable dye laser and a collimated atomic beam. The consistency of experimental isotope shifts is tested and values of the change in rms radius of the nuclear charge distribution are calculated.     

Observation of the second 4+ state in 28Si by means of proton inelastic scattering and analysis of the Kπ = 01+and 31− bands

High-resolution data from the ²⁸Si(p, p′) reaction have been obtained at E_p = 26.3 MeV. Separate cross sections for the 3₁^? and 4₂⁺ states at 6.879 and 6.889 MeV have been obtained. The strength of the 4₂⁺ state is much larger than reported in previous experimental papers. The 3₁^? state is well described in a coupled-channels calculation based on the rotation-vibration model.     

Growth and characterization of GaP and GaAs1−xPx

The minority carrier lifetime at low and high excitation densities was determined in VPE layers of GaP and GaAs_?0.2 P_?0.8. The lifetime at high excitation densities, having a value up to ∽350 ns, is one to two orders of magnitude larger than the lifetime at low excitation densities. It is shown that impurities are involved in some saturable killer centres dominating at low excitation densities. In the case of the largest values of the minority carrier lifetime and at a dislocation density of > 10⁵ cm^?2, the non-radiative recombination at high excitation densities is shown to occur at dislocations; at lower values of the minority carrier lifetime the killer action may be due to microprecipitates. These findings also hold for LPE layers of GaP. It is shown that by measuring the minority carrier lifetime as a function of temperature a discrimination is possible between killer action due to diffusion of minorities towards sinks like dislocations or microprecipitates and due to capture by a normal point-defect type recombination centre.     

Redox-state-dependent complex formation between pseudoazurin and nitrite reductase

Bacterial copper-containing nitrite reductase catalyzes the reduction of nitrite to nitric oxide as part of the denitrification process. Pseudoazurin interacts with nitrite reductase in a transient fashion to supply the necessary electrons. The redox-state dependence of complex formation between pseudoazurin and nitrite reductase was studied by nuclear magnetic resonance spectroscopy and isothermal titration calorimetry. Binding of pseudoazurin in the reduced state is characterized by the presence of two binding modes, a slow and a fast exchange mode, with a K(d)(app) of 100 microM. In the oxidized state of pseudoazurin, binding occurs in a single fast exchange mode with a similar affinity. Metal-substituted proteins have been used to show that the mode of binding of pseudoazurin is independent of the metal charge of nitrite reductase. Contrary to what was found for other cupredoxins, protonation of the exposed His ligand to the copper of pseudoazurin, His81, does not appear to be involved directly in the dual binding mode of the reduced form. A model assuming the presence of a minor form of pseudoazurin is proposed to explain the behavior of the complex in the reduced state.     

Constructing simple residuated lattices

A method of constructing residuated lattices is presented. As an application, examples of simple, integral, cancellative, distributive residuated lattices are given that are not linearly ordered. This settles a problem raised in [5] and [2].