Context. Although water is an essential and widespread molecule in star-forming regions, its chemical formation pathways are still not very well constrained. Observing the level of deuterium fractionation of OH, a radical involved in the water chemical network, is a promising way to infer its chemical origin. Aims. We aim at understanding the formation mechanisms of water by investigating the o...

Title of Document: TRACING CONTINENTALWEATHERING USING LITHIUM AND MAGNESIUM ISOTOPES: INSIGHTS FROM THE CHEMICAL WEATHERING OF COLUMBIA RIVER BASALTS AND MASS BALANCE MODELING Xiao-Ming Liu, Ph.D., 2013 Directed By: Professors Roberta L. Rudnick & William F. McDonough, Department of Geology Chemical weathering is an important mechanism that changes the mass and composition of the continental c...

Evidence from abyssal peridotites suggests that significant chemical reaction with peridotite can occur during the early stages of cooling and crystallization of mid-ocean ridge basalt (MORB) magmas. We evaluate the hypothesis that reactive crystallization (crystallization influenced by such melt^rock reaction) could cause magma compositions to evolve along a different chemical trajectory than ...

This paper deals with the chemical treatments with selected organic compounds that have been applied to Miscanthus to upgrade it, for pulp production or fractionation purposes. Organosolv processes have demonstrated their effectiveness as fractionation treatments; therefore special emphasis is placed on these systems and, in particular, those making use of carboxylic acids. That is, Acetosolv p...

The +0.1‰ elevated 56Fe/54Fe ratio of terrestrial basalts relative to chondrites was proposed to be a fingerprint of core-mantle segregation. However, the extent of iron isotopic fractionation between molten metal and silicate under high pressure-temperature conditions is poorly known. Here we show that iron forms chemical bonds of similar strengths in basaltic glasses and iron-rich alloys, eve...

Bioguided fractionation of the ethanol extracts obtained from Platycodon grandiflorum roots led to isolation of two new triterpenoid saponins, characterized as 3-O-beta-D-glucopyranosyl-2beta,12alpha,16alpha,23,24-pentahydroxyoleanane-28(13)-lactone (1) and 3-O-beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl-2beta,12alpha,16alpha,23alpha-tetrahydroxyoleanane-28(13)-lactone (2) by 1D- and 2D...

The role of biorefineries in the production of energy and chemicals from biomass of lignocellulosic nature is reviewed. Special attention is devoted to biorefinery schemes dealing with the fractionation of lignocellulosic raw materials by chemical treatments. The potential of hydrothermal treatments as the first stage of future biorefineries is discussed. Special attention is devoted to the low...

Stable carbon isotope fractionation during the reductive dechlorination of chloroethenes by two bacterial strains that dechlorinate to ethene, Dehalococcoides ethenogenes 195 and Dehalococcoides sp. strain BAV1 as well as Sulfurospirillum multivorans and Dehalobacter restrictus strain PER-K23, isolates that do not dechlorinate past DCE, are reported. Fractionation by a Dehalococcoides-containin...

Fly ash has been regarded as hazardous because of its high adsorption of toxic organic and/or inorganic pollutants. Fly ash is also known to have broad distributions of different chemical and physical properties, such as size and density. In this study, fly ash emitted from a solid waste incinerator was pre-fractionated into six sub-populations by use of gravitational SPLITT fractionation (GSF)...