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Hall D.A.,University of Manchester | Evans J.D.S.,Atomic Weapons Establishment | Covey-Crump S.J.,University of Manchester | Holloway R.F.,University of Manchester | And 3 more authors.
Acta Materialia | Year: 2010

The hydrostatic pressure-induced martensitic transformation from the ferroelectric rhombohedral to antiferroelectric orthorhombic phase in PZT 95/5 ceramics has been studied using neutron diffraction. The transition to the orthorhombic phase initiates at a pressure of 260 MPa and is almost complete at 290 MPa. This stress range is much narrower than that observed in uniaxial loading, which starts at 200 MPa and is incomplete even at 400 MPa. The narrower stress range observed under hydrostatic loading is attributed to a lack of internal stress developed during the transformation. By contrast, the work required to start the transformation is approximately the same under both types of loading. The transformation progresses more gradually with increasing pressure when a static electric field is applied to a specimen in a pre-poled state. Tests carried out on porous specimens, having a relative density of approximately 90%, demonstrated that the transformation occurred over a narrow pressure range but with a lower transformation pressure of approximately 220 MPa. © 2010 AWE and Crown Copyright. Published by Elsevier Ltd. All rights reserved. Source


George K.,University of Southampton | Jura M.,ISIS | Levason W.,University of Southampton | Light M.E.,University of Southampton | Reid G.,University of Southampton
Dalton Transactions | Year: 2014

The reaction of AlCl3 with Me2E (E = S, Se or Te) or nBu2E (E = Se or Te) in CH2Cl2 under rigorously anhydrous conditions gave the pseudo-tetrahedral complexes [AlCl3(R2E)]. The [AlX3(Me2E)] (X = Br or I, E = S; X = Br, E = Te) were made from toluene solution since attempted syntheses in CH2Cl2 resulted in substantial chloride incorporation. The synthesis of [(AlCl3)2{o-C 6H4(CH2SEt)2}], in which the ligand bridges two tetrahedral aluminium centres, and of the six-coordinate trans-[AlX2{MeE(CH2)2EMe}2][AlX 4] (X = Cl or Br, E = S, and X = Cl, E = Se) and cis-[AlI 2{MeS(CH2)2SMe}2][AlI4] are reported. The tripodal thioether forms [AlCl3{MeC(CH 2SMe)3}], which is a chain polymer with κ2-coordinated ligand and a tbp arrangement at Al(iii). Chalcogenoether macrocycle complexes [AlCl3([9]aneS3)], [AlCl2([14]aneS4)][AlCl4] and [AlCl 2([16]aneSe4)] [AlCl4] are also described. All complexes were characterised by microanalysis, IR and multinuclear NMR ( 1H, 27Al, 77Se or 125Te) spectroscopy as appropriate. In CH2Cl2 solution [AlCl 3(Me2S)] with added Me2S forms [AlCl 3(Me2S)2], and the [AlX2{MeS(CH 2)2SMe}2][AlX4] exist as mixtures of cis and trans isomers which undergo rapid exchange at ambient temperatures. X-Ray crystal structures are reported for [AlCl3(Me2Se], [AlX3(Me2Te)] (X = Cl or Br), trans-[AlCl 2{MeE(CH2)2EMe}2][AlCl4] (E = S or Se), cis-[AlI2{MeS(CH2)2SMe} 2][AlI4], [AlCl3{MeC(CH2SMe) 3}], and for the sulfonium salt [Me2SH][AlCl4]. The aluminium halide chalcogenoether chemistry is compared with the corresponding gallium and indium systems, and the relative Lewis acidities of the metals discussed. Attempts to use [AlCl3(nBu 2E)] (E = Se or Te) as LPCVD reagents to form aluminium chalcogenide films were unsuccessful. © 2014 The Royal Society of Chemistry. Source


Olivier J.-H.,University of Strasbourg | Harrowfield J.,ISIS | Ziessel R.,University of Strasbourg
Chemical Communications | Year: 2011

Synthetic routes for the construction of 3-substituted 2,4-pentadionate ligands are broadly surveyed. They involve sequential alkylation and arylation by numerous methods, including those based on reactions of coordinated ligands, and can provide access to various rationally designed ligands. Applications of such ligands in the synthesis of multichromophoric complexes are illustrated in some detail. Incorporation of 3-substituted 2,4-pentanedione units into mesomorphic and macromolecular structures is considered in relation to structural control of energy and electron transfer processes in photoactive systems. Aspects of the general supramolecular chemistry of complexes of 3-substituted-2,4-pentadionate ligands are briefly discussed to illustrate the utility of such species within the full range of 1,3-dionate chemistry. © 2011 The Royal Society of Chemistry. Source


The motivational interview helps nurses trained in this technique to optimise the motivational approach with the patient. This communication tool also gives them greater understanding of the resistance of people confronted with a chronic disease and to support them more effectively towards change. © 2014 Elsevier Masson SAS. All rights reserved. Source


Shen H.-H.,Physical and Theoretical Chemistry Laboratory | Thomas R.K.,Physical and Theoretical Chemistry Laboratory | Penfold J.,ISIS | Fragneto G.,ILL
Langmuir | Year: 2010

The lipopeptide surfactin from Bacillus subtilis strains exhibits strong surface and biological activity, the latter probably because of its interaction with biological membranes. We have investigated the interaction of aqueous solutions of surfactin with supported bilayers of diphosphatidylcholine (DPPC) on silica using neutron reflectometry. We have also used small-angle neutron scattering (SANS) to study the solubilized aggregates formed as a result of the destruction of the supported membrane by surfactin. Although surfactin on its own does not attach to the silica supporting surface, it is taken up from solution by the membrane, confirming that there is an attractive interaction between DPPC and surfactin. The surfactin concentration in the layer can reach up to about 20 mol % relative to DPPC. The membrane is stable provided that the surfactin concentration is below its critical micelle concentration (cmc, 5×10-5 M). Above the cmc, however, the membrane is solubilized and removed from the surface, though not always completely, over a period of hours. There are signs that there is an induction period while the surfactin concentration builds up in the membrane. This would be consistent with the need for a threshold concentration of surfactin in the bilayer. The presence of a surfactin correlation peak in the SANS showed that in the bulk solution, at the same concentrations as used for the deposition, surfactin forms aggregates that must be localized in the DPPC multilamellar vesicles at a separation of about 160 Å. The structure could be fitted with an approximate model where the surfactin has an aggregation number of 50 ± 10 with a radius of about 27 Å. Given the very small water thicknesses in the DPPC lamellar aggregates, the surfactin must exist as aggregates in the phospholipid bilayer, and these structures are responsible for solubilizing the DPPC. © 2010 American Chemical Society. Source

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