Preparation of Oxopentachloro-, Oxopentathiocyanato- & Oxochlorotetra-thiocyanato- rhenates(V) from H2ReOCl5 in Non-aqueous Medium

771-77

Preparation of Oxotetrachlororhenates (V) from H2ReOCl5 in Acetic Acid

74-7

Synthesis of Oxopentathiocyanato-rhenate(V) from Oxopentachloro-rhenate(VI) & Its Characterisation

1072-107

New Preparative Methods for Oxopentachlororhenates(V) & Their Isolation in Two Magnetic Forms

847-85

An Improved Thiocyanate Method for the Determination of Rhenium

879-88

The beryllium-10 concentration in deep-sea sediments

The cosmic-ray-produced radioactive isotope, 10Be (half-life 2.7 million years) has been discovered in the upper and lower portions of a 15 m long core from the sediment of the Pacific Ocean. A comparatively simple chemical procedure for its extraction has been developed. If the investigated core represents sedimentation which has remained physically and chemically undisturbed for several million years, the following tentative conclusions can be drawn: The measured concentrations of 10Be in layers at various depth indicate a sedimentation rate of about 5 mm/1,000 years which is not far from current estimates. The concentration in the upper layers leads to a present-day deposition rate of 2.55 × 101010Be nuclei/cm2 year, in excellent agreement with estimates based on the 7Be contents of rainwater. The decrease of concentration with depth indicates an intensity of cosmic rays in the past which has changed not at all or very slowly during the last ca. 2.5 million years

Prehistoric cosmic ray intensity

This article does not have an abstract