Atomic level termination for passivation and functionalisation of silicon surfaces.

Chemical treatments play an essential role in the formation of high quality interfaces between materials, including in semiconductor devices, and in the functionalisation of surfaces. We have investigated the effects of hydrogen and fluorine termination of (100)-orientation silicon surfaces over a range of length scales. At the centimetre scale, lifetime measurements show clean silicon surfaces can be temporarily passivated by a short treatment in both HF(2%) : HCl(2%) and HF(50%) solutions. The lifetime, and hence surface passivation, becomes better with immersion time in the former, and worse with immersion time in the latter. At the nanometre scale, X-ray photoelectron spectroscopy and atomic force microscopy show treatment with strong HF solutions results in a roughened fluorine-terminated surface. Subsequent superacid-derived surface passivation on different chemically treated surfaces shows considerably better passivation on surfaces treated with HF(2%) : HCl(2%) compared to HF. Lifetime data are modelled to understand the termination in terms of chemical and field effect passivation at the centimetre scale. Surfaces passivated with Al2O3 grown by atomic layer deposition behave similarly when either HF(2%) : HCl(2%) or HF(50%) are used as a pre-treatment, possibly because of the thin silicon dioxide interlayer which subsequently forms. Our study highlights that chemical pre-treatments can be extremely important in the creation of high quality functionalised surfaces.

Leadership and management in UK medical school curricula.

Purpose Although medical leadership and management (MLM) is increasingly being recognised as important to improving healthcare outcomes, little is understood about current training of medical students in MLM skills and behaviours in the UK. The paper aims to discuss these issues. Design/methodology/approach This qualitative study used validated structured interviews with expert faculty members from medical schools across the UK to ascertain MLM framework integration, teaching methods employed, evaluation methods and barriers to improvement. Findings Data were collected from 25 of the 33 UK medical schools (76 per cent response rate), with 23/25 reporting that MLM content is included in their curriculum. More medical schools assessed MLM competencies on admission than at any other time of the curriculum. Only 12 schools had evaluated MLM teaching at the time of data collection. The majority of medical schools reported barriers, including overfilled curricula and reluctance of staff to teach. Whilst 88 per cent of schools planned to increase MLM content over the next two years, there was a lack of consensus on proposed teaching content and methods. Research limitations/implications There is widespread inclusion of MLM in UK medical schools' curricula, despite the existence of barriers. This study identified substantial heterogeneity in MLM teaching and assessment methods which does not meet students' desired modes of delivery. Examples of national undergraduate MLM teaching exist worldwide, and lessons can be taken from these. Originality/value This is the first national evaluation of MLM in undergraduate medical school curricula in the UK, highlighting continuing challenges with executing MLM content despite numerous frameworks and international examples of successful execution.

Paired gill slits in a fossil with a calcite skeleton.

The chordates, hemichordates (such as acorn worms) and echinoderms (such as starfish) comprise the group Deuterostomia, well established as monophyletic. Among extant deuterostomes, a skeleton in which each plate has the crystallographic structure of a single crystal of calcite is characteristic of echinoderms and is always associated with radial symmetry and never with gill slits. Among fossils, however, such a skeleton sometimes occurs without radial symmetry. This is true of Jaekelocarpus oklahomensis, from the Upper Carboniferous of Oklahoma, USA, which, being externally almost bilaterally symmetrical, is traditionally placed in the group Mitrata (Ordovician to Carboniferous periods, 530-280 million years ago), by contrast with the bizarrely asymmetrical Cornuta (Cambrian to Ordovician periods, 540 to 440 million years ago). Using computer X-ray microtomography, we describe the anatomy of Jaekelocarpus in greater detail than formerly possible, reveal evidence of paired gill slits internally and interpret its functional anatomy. On this basis we suggest its phylogenetic position within the deuterostomes.