Deuterium isotope effects on iron core formation in ferritin

We present comparative Mössbauer investigations of nanosized FeOOH and FeOOD biomineral phases nucleated within the 7-nm diameter cavity of horse-spleen apoferritin in order to assess deuterium isotopic effects on nanoscale, bioinorganic lattice structures with extended hydrogen bond networks. Differences in magnetic anisotropy energy, packing density and degree of crystallinity in the resulting iron oxo-hydroxide nanophases obtained via D₂O (heavy water) vs. H₂O (light water) solution chemistry are noted. These observations point to the possibility of stabilizing new thermodynamic states in the solid-state by utilizing isotope effects, with important implications for new synthetic pathways to novel nano materials.     

Influence of acceptor and donor adsorbates (CO,K, NH3) on Pt surface core-level shifts

4f core-level shifts have been measured for clean surfaces of Pt(111), Pt(331), and Pt(557). Surface peaks due to terrace sites are shifted toward lower binding energy (0.32 ± 0.05 eV) from the bulk peak, whereas peaks from step atoms are shifted by 0.58 ± 0.05 eV also to lower binding energy. The intensity ratios for the two sites differ considerably between the stepped Pt surfaces. Chemisorption of carbon monoxide on the Pt(331) surface is preferential to step sites, with a Pt 4f binding energy shift of ～ 1.29 eV toward higher binding energy. Chemisorption of potassium and ammonia also produces Pt 4f surface shifts which are at higher binding energy than the bulk peak. These experiments do not support the concept of electron donation by these adsorbates into metal d orbitals. The results are discussed in view of, and supported by, tight-binding LCAOMO calculations of potassium and ammonia interacting with a Pt(111) thin film.     

Intrinsic surface binding energy shifts in Yb metal

We report on the four-peak structure observed in the region of 4f photoemission in Yb metal, using synchrotron radiation in the energy range 70–200 eV. We conclude, contrary to previous reports, that the doublet associated with surface emissions results from an intrinsic surface shift on clean regions of the surface. We also demonstrate that the observed structure is consistent with earlier XPS measurements, and we set an upper limit on the width of the bulk peaks.     

Copper and iron interactions with angiotensin-converting enzyme inhibitors. A study by fast-atom bombardment tandem mass spectrometry

Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd.     

Determination of loads applied perpendicularly to the outer boundary of a ring using coefficients of influence

A procedure is explained to determined the amount of several pairs of diametrical loads applied to the outside boundary of a ring when stresses at selected points of the inside or outside boundaries are known. Coefficients of influence are used, following an approach similar to the one presented in a previous paper. Examples of application are given and the possible increase in precision is shown when the number of points of measurements is larger than the number of loads to be determined.