Switching Lead for Tin in PbHfO3 : Noncubic Structure of SnHfO3.

The removal of lead from commercialized perovskite-oxide-based piezoceramics has been a recent major topic in materials research owing to legislation in many countries. In this regard, Sn(II)-perovskite oxides have garnered keen interest due to their predicted large spontaneous electric polarizations and isoelectronic nature for substitution of Pb(II) cations. However, they have not been considered synthesizable owing to their high metastability. Herein, the perovskite lead hafnate, i.e., PbHfO3 in space group Pbam, is shown to react with SnClF at a low temperature of 300 °C, and resulting in the first complete Sn(II)-for-Pb(II) substitution, i.e. SnHfO3 . During this topotactic transformation, a high purity and crystallinity is conserved with Pbam symmetry, as confirmed by X-ray and electron diffraction, elemental analysis, and 119 Sn Mössbauer spectroscopy. In situ diffraction shows SnHfO3 also possesses reversible phase transformations and is potentially polar between ≈130-200 °C. This so-called 'de-leadification' is thus shown to represent a highly useful strategy to fully remove lead from perovskite-oxide-based piezoceramics and opening the door to new explorations of polar and antipolar Sn(II)-oxide materials.

Renaissance of Topotactic Ion-Exchange for Functional Solids with Close Packed Structures.

Recently, many new, complex, functional oxides have been discovered with the surprising use of topotactic ion-exchange reactions on close-packed structures, such as found for wurtzite, rutile, perovskite, and other structure types. Despite a lack of apparent cation-diffusion pathways in these structure types, synthetic low-temperature transformations are possible with the interdiffusion and exchange of functional cations possessing ns2 stereoactive lone pairs (e. g., Sn(II)) or unpaired ndx electrons (e. g., Co(II)), targeting new and favorable modulations of their electronic, magnetic, or catalytic properties. This enables a synergistic blending of new functionality to an underlying three-dimensional connectivity, i. e., [-M-O-M-O-]n , that is maintained during the transformation. In many cases, this tactic represents the only known pathway to prepare thermodynamically unstable solids that otherwise would commonly decompose by phase segregation, such as that recently applied to the discovery of many new small bandgap semiconductors.

Evaluation of a novel nutrition education intervention for medical students from across England.

OBJECTIVES: Problems such as hospital malnutrition (∼40% prevalence in the UK) may be managed better by improving the nutrition education of 'tomorrow's doctors'. The Need for Nutrition Education Programme aimed to measure the effectiveness and acceptability of an educational intervention on nutrition for medical students in the clinical phase of their training. DESIGN: An educational needs analysis was followed by a consultative process to gain consensus on a suitable educational intervention. This was followed by two identical 2-day educational interventions with before and after analyses of Knowledge, Attitudes and Practices (KAP). The 2-day training incorporated six key learning outcomes. SETTING: Two constituent colleges of Cambridge University used to deliver the above educational interventions. PARTICIPANTS: An intervention group of 100 clinical medical students from 15 medical schools across England were recruited to attend one of two identical intensive weekend workshops. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome measure consisted of change in KAP scores following intervention using a clinical nutrition questionnaire. Secondary outcome measures included change in KAP scores 3 months after the intervention as well as a student-led semiqualitative evaluation of the educational intervention. RESULTS: Statistically significant changes in KAP scores were seen immediately after the intervention, and this was sustained for 3 months. Mean differences and 95% CIs after intervention were Knowledge 0.86 (0.43 to 1.28); Attitude 1.68 (1.47 to 1.89); Practice 1.76 (1.11 to 2.40); KAP 4.28 (3.49 to 5.06). Ninety-seven per cent of the participants rated the overall intervention and its delivery as 'very good to excellent', reporting that they would recommend this educational intervention to colleagues. CONCLUSION: Need for Nutrition Education Programme has highlighted the need for curricular innovation in the area of clinical health nutrition in medical schools. This project also demonstrates the effectiveness and acceptability of such a curriculum intervention for 'tomorrow's doctors'. Doctors, dietitians and nutritionists worked well in an effective interdisciplinary partnership when teaching medical students, providing a good model for further work in a healthcare setting.