Profex: a graphical user interface for the Rietveld refinement program BGMN.

Profex is a graphical user interface for the Rietveld refinement program BGMN. Its interface focuses on preserving BGMN's powerful and flexible scripting features by giving direct access to BGMN input files. Very efficient workflows for single or batch refinements are achieved by managing refinement control files and structure files, by providing dialogues and shortcuts for many operations, by performing operations in the background, and by providing import filters for CIF and XML crystal structure files. Refinement results can be easily exported for further processing. State-of-the-art graphical export of diffraction patterns to pixel and vector graphics formats allows the creation of publication-quality graphs with minimum effort. Profex reads and converts a variety of proprietary raw data formats and is thus largely instrument independent. Profex and BGMN are available under an open-source license for Windows, Linux and OS X operating systems.

Schwertmannite formation adjacent to bacterial cells in a mine water treatment plant and in pure cultures of Ferrovum myxofaciens.

Schwertmannite has previously been found in iron- and sulfate-rich mine waters at pH 2.8-4.5. In the present study, schwertmannite (Fe(8)O(8)(OH)(6)SO(4)) was shown to be the major mineral in a mine water treatment plant at pH 3, in which ferrous iron is mainly oxidized by bacteria belonging to the species Ferrovum myxofaciens. Strain EHS6, which is closely related to the type strain of Fv. myxofaciens, was isolated from the pilot plant and characterized as an acidophilic, iron-oxidizing bacterium. In contrast to the pilot plant, the mineral phase formed by a pure culture of Fv. myxofaciens EHS6 was a mixture of schwertmannite and jarosite (KFe(3)(SO(4))(2)(OH)(6)). In contrast to other reports of neutrophilic, iron-oxidizing bacteria, acidophilic microorganisms in the pilot plant and cultures of strain EHS6 did not show encrustation of the cell surface or deposition of minerals inside the cell, though a few cells appeared to be in contact with jarosite crystals. It was concluded that no direct biomineralization occurred in the pilot plant or in laboratory cultures. The lack of encrustation of bacterial cells in the pilot plant is considered advantageous since the cells are still able to get in contact with ferrous iron and the iron oxidation process in the mine water treatment plant can proceed.

Influence of experimental parameters on spatial phase distribution in as-sprayed and incubated hydroxyapatite coatings.

In the present study, the behavior and properties of plasma-sprayed hydroxyapatite coatings [Ca(10)(PO(4))(6)(OH)(2), HAp] were investigated in relation to the spraying process. The experiments were focused on the influence of type of feedstock and spray power on the phase composition and distribution within the coatings. Depth profiles of the coatings were investigated before and after incubation in revised simulated body fluid (SBF) by X-ray diffraction and infrared spectroscopy. Besides HAp, the coatings contain oxyapatite (OAp) and carbonate apatite (CAp). Additionally, tricalcium phosphate (TCP), tetracalcium phosphate (TTCP), CaO, and an amorphous phase were detected in the coatings. The HAp content directly depends on the used spray powder and spray power, where the influence of spray powder is much higher than the influence of the spray power. The grain size range of the spray powder strongly influences the HAp content in the coating and the formation of CaO. The in vitro behavior of the coatings in simulated body fluid mainly depends on the contents of CaO and amorphous calcium phosphate, respectively. The formation of portlandite due to the reaction of the coating with the SBF is strongly influenced by the porosity of the coatings and can be used as an indicator for the depth of interaction between fluid and coating.