Bio-signatures play a central role in determining whether life existed on early Mars. Using a terrestrial basalt as a compositional analog for the martian surface, we applied a combination of experimental microbiology and thermochemical modeling techniques to identify potential geochemical bio-signatures for life on early Mars. Laboratory experiments were used to determine the short-term effect...

As part of a theoretical study of adsorption processes in the chemical vapour deposition of silicon, thermochemical data are derived for the adsorption of Si—H species on the Si(111) and the dimer-reconstructed Si(001)-(2 xl) surfaces. Essential contributions to the heats of adsorption appear to be electron pairing and twoand three-body interactions. It is shown that when the bond energies are ...

Chemical disequilibrium has recently become a relevant topic in the study of the atmospheres of of transiting extrasolar planets, brown dwarfs, and directly imaged exoplanets. We present a new way of assessing whether or not a Jovian-like atmosphere is in chemical disequilibrium from observations of detectable or inferred gases such as H2O, CH4, CO, and H2. Our hypothesis, based on previous kin...

A combined quantummechanical and thermodynamic approach to the mechanical properties of multicomponent silicate glasses is presented. Quantum chemical calculations based on density functional theory on various silicate systems were performed to explore the crystalline polymorphs existing for a given chemical composition. These calculations reproduced the properties of known polymorphs even in s...

A thermochemical representation of the Na-Al-Si-B-O system relevant for nuclear waste glass has been developed based on the associate species approach for the glass solution phase. Thermochemical data were assessed and associate species data determined for binary and ternary subsystems in the Na2O-Al2O3-B2O3-SiO2 system. Computed binary and ternary phase diagrams were compared to published diag...

The Cu-Cl thermochemical cycle for hydrogen production was selected on the basis of its high efficiency and moderate temperature requirements. The modeling and simulation of Cu-Cl thermochemical cycle for hydrogen production is investigated in Aspen Plus. Since this cycle is a high energy-consuming process, the heat integration technique is implemented to recover the waste heat such that the pr...

The effect of substitution of Al(3+), Ga(3+) and Sc(3+) ions in the Mn(3+) site of La0.5Sr0.5MnO3 on the thermochemical splitting of CO2 to generate CO has been studied in detail. Both La0.5Sr0.5Mn1-xGaxO3 and La0.5Sr0.5Mn1-xScxO3 give high yields of O2 and generate CO more efficiently than La0.5Sr0.5Mn1-xAlxO3 or the parent La0.5Sr0.5MnO3. Substitution of even 5% Sc(3+) (x = 0.05) results in a...

0022-2852/$ see front matter 2010 Elsevier Inc. A doi:10.1016/j.jms.2010.09.005 ⇑ Corresponding author at: Department of Chem University of Arizona, 933 N. Cherry Ave., Tucson, AZ 5554. E-mail address: [email protected] (L.M. Ziury 1 Present address: National Radio Astronomy Obs Charlottesville, VA 22903, USA. The pure rotational spectrum of TiS in its XDr ground state has been measured us...

Thermochemical sulfate reduction experiments with simple amino acid and dilute concentrations of sulfate reveal significant degrees of mass-independent sulfur isotope fractionation. Enrichments of up to 13‰ for (33)S are attributed to a magnetic isotope effect (MIE) associated with the formation of thiol-disulfide, ion-radical pairs. Observed (36)S depletions in products are explained here by c...