Biomedical subjects

C R Catlow

Publications and source records attributed to C R Catlow.

6 recordsLinked to original sources

PubMed2001

Interatomic potential parameters for potassium tetrachlorozincate and their application to modelling its phase transformations.

An empirical fitting procedure is applied to derive interatomic potential parameters for a model phase transition system, namely potassium tetrachlorozincate (K(2)ZnCl(4)). The derived potential is found to reliably model the known crystallographic structure for the ferroelectric and paraelectric phases of this compound. Potential transferability is demonstrated by applying the parameters derived to the optimization of the known molecular structure for a similar inorganic system (rubidium tetrachlorozincate).

Journal Article↗

PubMed2001

Effect of Si(IV) substitution on the stability of microporous ZnAPSO-44 solid acid catalysts: a combined XAS/XRD study.

The combined XAS/XRD technique has been used to investigate the stability of the microporous structure during calcination process for a series of ZnAPSO-44 materials. Incorporation of large amounts of Zn is found to produce materials that are unstable upon removal of the structure directing organic template molecule. However, simultaneous incorporation of Si is found to increase the thermal stability of the materials, yielding catalysts that are well suited for acid catalysed reactions.

Journal Article↗

PubMed2001

The architecture of Mg(II) centres in MAPO-36 solid acid catalysts.

The local structure around Mg2+ ions of a Magnesium substituted aluminophosphate, with the ATS structure (MgAPO-36, Mg/P=0.08), in the as-prepared and calcined state has been investigated by Mg K-edge XAS spectroscopy. High quality XAS data were collected using the solid-state fluorescence detector. Mg2+ is found to replace tetrahedrally co-ordinated Al3+ in the as-prepared state and remained intact even after calcination, thus yielding a highly active, solid acid catalyst.

Journal Article↗

PubMed1997

A New High-Flux Chemical and Materials Crystallography Station at the SRS Daresbury. 1. Design, Construction and Test Results.

A new single-crystal diffraction facility has been constructed on beamline 9 of the SRS at Daresbury Laboratory for the study of structural problems in chemistry and materials science. The station utilizes up to 3.8 mrad horizontally from the 5 T wiggler magnet which can be focused horizontally and vertically. The horizontal focusing is provided by a choice of gallium-cooled triangular bent Si (111) or Si (220) monochromators, giving a wavelength range from 0.3 to 1.5 A. Focusing in the vertical plane is achieved by a cylindrically bent zerodur mirror with a 300 mum-thick palladium coating. The station is equipped with a modified Enraf-Nonius CAD-4 four-circle diffractometer and a Siemens SMART CCD area-detector system. High- and low-temperature facilities are available to cover the temperature range from about 80 to 1000 K. Early results on test compounds without optimization of the beam optics demonstrate that excellent refined structures can be obtained from samples giving diffraction patterns too weak to be measured with conventional laboratory X-ray sources, fulfilling a major objective of the project.

Journal Article↗

PubMed1988

Strategies for modelling of catalysts.

The strategy summarised above in which modelling calculations are combined with QM cluster calculations is a viable procedure for the study of catalysis. Our discussion has emphasized studies of zeolite catalysts but the same approach could be used in modelling reactions catalysed on metal and metal oxide surfaces. Moreover, the techniques and potentials are available for these methods to have a wide range of applications.

Catalysis↗

PubMed1986

The conformation of apamin.

Energy minimization techniques are used as a tool to distinguish between different proposed models for the structure of the bee venom polypeptide apamin. The influence of electrostatic interactions on the resultant energies is noted. The model of Hider and Ragnarsson [(1980) FEBS Lett. 111, 189-193] is found to be of consistently low energy.

Apamin↗