[1] Lavas from the early episodes of the Pu`u `Ō`ō eruption (1983–1985) of Kı̄lauea Volcano on the island of Hawai^i display rapid compositional variation over short periods for some episodes, especially the well-sampled episode 30 with 2 wt% MgO variation in <4 hours. Little chemical variation is observed within the episode 30 lavas before or after this abrupt change, suggesting a sharp composi...

• Different impact of electron beam irradiation on aliphatic and aromatic thermoplastic polyurethanes. Degradation, chain scission snd crosslinking depends dose temperature. ThFFF as an alternative approach for advanced analysis crosslinked polymer structures. The polyurethane material was studied both with approximately equal molar amount hard soft segments. Irradiation doses up to 300 kGy (ki...

In support of programs to identify polyhydroxyalkanoates with improved materials properties, we report on our efforts to characterize the mechanical and thermal properties of copolyesters of 3-hydroxybutyrate (3HB) and 3-hydroxyhexanoate (3HHx). The copolyesters, having molar fraction of 3HHx ranging from 2.5 to 35 mol % and average molecular weights ranging from 1.15 x 10(5) to 6.65 x 10(5), w...

Most of the organic nitrogen (Norg) on Earth is disseminated in crustal sediments and rocks in the form of fossil nitrogen-containing organic matter. The chemical speciation of fossil Norg within the overall molecular structure of organic matter changes with time and heating during burial. Progressive thermal evolution of organic matter involves phases of enhanced elimination of Norg and ultima...

Introduction The hafnium-tungsten (Hf-W) isotopic system provides a powerful constraint on accretion and core formation timescales [1-3]. However, most estimates of these timescales employ analytical expressions assuming either continuous planetary growth or instantaneous core formation. In contrast, dynamical modelling of planetary accretion suggests that the final stage of terrestrial planet ...

The analysis of polycyclic aromatic hydrocarbons (PAH) in ambient air requires the tedious experimental steps of both sampling and pretreatment (e.g., extraction or clean-up). To replace pre-existing conventional methods, a simple, rapid, and novel technique was developed to measure gas-particle fractionation of PAH in ambient air based on 'sorbent tube-thermal desorption-gas chromatograph-mass...

Many experiments in which an element or a mineral is evaporated or thermally decomposed under vacuum are known to consistently display unexpected behaviors. These include too low rates of evaporation, smaller (i.e. closer to 1) than predicted fractionation factors, and an inconsistent behavior of the stable isotope ratios of a given element (i.e. massindependent fractionation). This applies to ...

available online at http://meteoritics.org 1509 © Meteoritical Society, 2004. Printed in USA. Potassium isotopic composition of Australasian tektites Munir HUMAYUN1†* and Christian KOEBERL2 1Department of Geophysical Sciences, The University of Chicago, Chicago, Illinois 60637, USA 2Department of Geological Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria †Present addres...