Crystals of magnetite (Fe(3)O(4)) and periclase (MgO) in Fe-Mg-Ca carbonate in the Martian meteorite Allan Hills 84001 were studied by using transmission electron microscopy to understand their origin and evaluate claims that the magnetites were made by Martian microorganisms. In magnesian carbonate, periclase occurs as aggregates of crystals (grain size approximately equal to 3 nm) that are pr...

The application of a linear algebraic method to the potentiometric titration of a mixture of tartaric and citric acids and sodium carbonate and sodium hydrogen carbonate (previously treated with strong acid), permits the determination of the concentration of each individual acid and the total equivalent of carbonate in antacids. It is also possible to determine individual concentrations of sodi...

We present a revised approach for standardizing and reporting analyses of multiply substituted isotopologues of CO2 (i.e., ‘clumped’ isotopic species, especially the mass-47 isotopologues). Our approach standardizes such data to an absolute reference frame based on theoretical predictions of the abundances of multiply-substituted isotopologues in gaseous CO2 at thermodynamic equilibrium. This r...

The feasibility of calcium carbonate cements involving the recrystallisation of metastable calcium carbonate varieties has been demonstrated. Calcium carbonate cement compositions presented in this paper can be prepared straightforwardly by simply mixing water (liquid phase) with two calcium carbonate phases (solid phase) which can be easily obtained by precipitation. An original cement composi...

definition of carbonate sediments to include those containing more than SO per cent carbonate minerals, many new parameters can be studied and new and useful information can be incorporated in studies of carbonate rocks. It is obvious that, by enlarging the definition, consideration of insoluble residues and stratigraphic associations is possible. Further, the geographic range of carbonate sedi...

BACKGROUND Lanthanum carbonate and sevelamer carbonate are non-calcium-based phosphate binders used to manage hyperphosphataemia in patients with chronic kidney disease (CKD). Patients with CKD may require intravenous or oral active vitamin D. We investigated the effects of lanthanum carbonate and sevelamer carbonate on the bioavailability of oral calcitriol. METHODS This was a three-period, ...

We designed a novel multifunctional β-sheet peptide template for calcium carbonate mineralization. The template self-supplies the mineral source, a carbonate ion, by hydrolysis of urea, and regulates the crystal phase and morphology of the obtained calcium carbonate.

tion state of the world’s oceans are changing as a result of the addition of fossil fuel CO2 to the atmosphere (Kleypas et al. 1999; Feely et al. 2004; Orr et al. 2005). The pH of surface oceans has dropped by 0.1 units since the industrial revolution and if fossil fuel combustion continues at present rates, the pH of the world’s oceans will probably drop another 0.3 to 0.4 units by 2100 (Mehrb...

Increasing dissolved inorganic carbon (DIC) concentrations associated with ocean acidification can affect marine calcifiers, but local factors, such as high dissolved organic carbon (DOC) concentrations through sewage and algal blooms, may interact with this global factor. For calcifying green algae of the genus Halimeda, a key tropical carbonate producer that often occurs in coral reefs, no st...

A novel di-iron(III) catalyst for the copolymerisation of cyclohexene oxide and CO(2) to yield poly(cyclohexene carbonate), under mild conditions, is reported. The catalyst selectivity was completely changed on addition of an ammonium co-catalyst to yield only the cis-isomer of the cyclic carbonate, also under mild conditions. Additionally, the catalyst was active for propylene carbonate and st...