Powder Data Conversion

Software References or contact information Specialization Freely Available 

American Mineralogist Crystal Structure The American Mineralogist Crystal Structure Database, R. T. Downs and M. Hall Wallace, Am. Mineral, 2003, 88, 247 250 Minerals Yes 

CCDC/Cambridge Structure Database The Cambridge Structural Database a quarter of a million crystal structures and rising, F. H. Allen, Acta Crystallogr., Sect. B, 2002, 58, 380 388 Organics and Organometallics  

CDS (EPSRC funded The United Kingdom Chemical Database Access to a large number of Yes (within the 

Chemical Database Service , D. A. Fletcher, R. F. McMeeking, scientific databases to UK UK) 

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With CIF becoming a more used standard in the powder diffraction community, structure data conversion is becoming less needed on a day-to-day basis. The Powder Cell format is probably the next best format due to its relative simplicity compared to CIF. Most structure databases can export files into CIF format, and some to Powder Cell format. Eric Dowty s Cryscon software is currently the most comprehensive structure data conversion and transformation (Table 17.8). However, due care should be shown and results checked. Normally, the programs are robust, and it is more a case of users selecting options without understanding the consequences. 

Table 17.6 Available powder diffraction data conversion software and supported file types. 

POWF a program for powder data file conversion, R.J. Angel, (2005), Virginia Tech Crystallography Laboratory, 3076 Derring Flail, Virgina Tech, Blacksburg, VA 24060, USA http //... 

Table 17.7 Some text editors and spreadsheet programs with useful features for powder diffraction data conversion.

A substantial portion ( 15%) of the magnetite was found to be converted to hematite. As prior work showed small conversion (1%) of hematite to magnetite, the data indicate that the conversion can proceed in either direction depending upon the local microscopic deformation history of the powder particles. 

Temperature-mediated transformations also occur. Ali et al. collected simultaneous Raman spectra and DSC curves of satmeterol xinafoate, detecting two forms [250]. Raman spectroscopy was used to follow the conversions of erythromycin A dihydrate as a function of temperature conditions were identified where the Raman data provided more insights into the kinetics than powder XRD [251]. 

Aust. J. Soil Res. 16 215-227 Joint Committee on Powder Diffraction Standards Mineral powder diffraction fde. Data book. Published by the JCPDS International Centre for Diffraction Data, Swarfhmore, Pennsylvania, U SA, pp. 942 Jolivet, J.P. Tronc, E. (1988) Interfadal electron transfer in colloidal spinel iron oxide. Conversion of Fe304 to y- Fe203 in aqueous medium. J. Colloid Interface Sci. 125 688—... 

Microbiological tests have indicated that penicillin G is stable to heat. Pasteurization temperatures and times commonly applied to milk and milk products are inadequate for inactivation of tlie antibiotic if it is present (26-29). At 71 C, a total of 1705 min was required to inactivate completely penicillin G in milk, whereas at boiling temperatures or above, all data indicated that a portion of tire penicillin activity in milk survived boiling for 60 min or autoclaving at 15 psi steam pressure for 15-30 min (26, 29). Milk from treated cows retained some of its antimicrobial activity even after conversion to dried skim milk powder (30). 

The crystal structure of the cocrystal formed by celecoxib (4-[5-(4-methylphenyl)-3-(trifluoromethyl)-lH-pyrazol-l-yl]benzenesulfonamide) with nicotinamide has been solved from powder X-ray diffraction data [54], The dissolution and solubility of the cocrystal product were found to depend on the medium involved, and a number of the observed phenomena were shown to originate from differences in conversion of the cocrystal celecoxib polymorphic forms I and III. However, through the judicious use of choice excipients, a formulation was developed that took advantage of the crystalline conversion to be up to fourfold more bioavailable than the celecoxib Form-Ill marketed product. 

The comprehensive investigation of the interactions of simple alcohols (methanol, ethanol, propan-l-ol, and butan-l-ol) with Fe203 powders (514) by a combination of surface analytical techniques and conversion measurements under high vacuum and at atmospheric pressure is an example of the attempts to establish correlations between surface structure and catalytic activity. IR and XPS data showed that methanol is chemisorbed mainly disso-ciatively, giving formate species, whereas molecular chemisorption prevails for higher alcohols, which form hydrocarbons as the major products. 

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