A Mössbauer spectroscopy study on iron in marine sediments

The chemical states of iron in near-shore and deep-sea sediments were investigated by means of⁵⁷Fe Mössbauer spectroscopy using selective and chemical leachings. The Fe²⁺/Fe³⁺ ratios of deep-sea sediments were much smaller than those of near-shore sediments, while the total contents of iron in the former were much higher than those in the latter. This is principally due to the high content of hydrogenous ferric oxyhydroxide in deep-sea sediments. Also, in the aluminosilicate fraction, the Fe²⁺/Fe³⁺ ratios of deep-sea sediments were smaller than those of near-shore sediments. This is probably attributed to the difference in the silicate mineral composition between deep-sea and near-shore sediments. X-ray reflections of clay minerals normalized to those of feldspars and quartz were more intense in deep-sea sediments than in near-shore sediments.     

The Euler obstruction of a function on a determinantal variety and on a curve

Given an analytic function germ f: (X, 0) → C on an isolated determinantal singularity or on a reduced curve, we present formulas relating the local Euler obstruction of f to the vanishing Euler characteristic of the fiber X ∩ f^-1(0) and to the Milnor number of f. Restricting ourselves to the case where X is a complete intersection, we obtain an easy way to calculate the local Euler obstruction of f as the difference between the dimension of two algebras.     

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.     

Supercontinuum generation with femtosecond self-healing Airy pulses

We report experiments and numerical simulations on supercontinuum generation with femtosecond Airy pulses in a highly nonlinear optical fiber. The ability of the Airy waveform to regenerate its dominant intensity peak results in the generation of distinct spectral features. Airy pulses and other self-healing temporal waveforms may be useful for the generation of spectra with desired properties.