Growth induced reordering of fullerene clusters trapped in a two-dimensional supramolecular network.

We have investigated the growth of molecular clusters in confined geometries defined by a bimolecular supramolecular network. This framework provides a regular array of identical nanoscale traps in which further deposited molecules nucleate cluster growth. For the higher fullerene, C84, molecules aggregate into close packed assemblies with an orientation which switches when the cluster size increases by one molecule. This change is controlled by the interactions between the molecules and the confining boundaries of the network pore. We show that, following nucleation of small clusters, further growth requires a reconfiguration of previously captured molecules resulting in a transition between nanoscale phases with different ordering.

Square, hexagonal, and row phases of PTCDA and PTCDI on Ag-Si(111)square root(3) x square root(3)R30 degrees.

We have investigated the ordered phases of the perylene derivatives perylene-3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride (PTCDA) and the imide analogue PTCDI on the Ag-Si(111)square root(3) x square root(3)R30 degrees surface using scanning tunneling microscopy. We find that PTCDA forms square, hexagonal, and herringbone phases, which coexist on the surface. The existence of a square phase on a hexagonal surface is of particular interest and is a result of a near commensurability between the molecular dimensions and the surface lattice. Contrast variations across the square islands arise from PTCDA molecules binding to different sites on the surface. PTCDI on Ag-Si(111)square root(3) x square root(3)R30 degrees forms extended rows, as well as two-dimensional islands, both of which are stabilized by hydrogen bonding mediated by the presence of imide groups. We present models for the molecular arrangements in all these phases and highlight the role of hydrogen bonding in controlling this order.

Sexual health provision and the Sexual Health and HIV Strategy for England: a questionnaire survey of general practitioners' views.

An anonymous postal survey was used to assess the views of general practitioners (GPs) on the expected contents of the Department of Health National Sexual Health and HIV Strategy for England prior to release. One hundred and seventeen GPs in four London Primary Care Groups took part (response rate=50%). The majority felt they currently have about the right amount of involvement in patient care (HIV 70%: GUM 66%); 88% of GPs felt they offer general sexual health care (Level one), and most wished to continue with this (85%). However, a sizeable minority of GPs wanted to be involved in the development of care guidelines (HIV 17%; GUM 22%), and 10% considered that they might wish to offer more specialist services (Level two). To achieve a Strategy goal to integrate sexual healthcare services in England, it is likely that there will need to be local consultation and support for GPs.

Chromosome identification of the flat-headed cat, Felis planiceps: one more down and five to go.

There are 38 recognized feline species in the world. With successful chromosome analysis of the flat-headed cat, Felis planiceps or Prionailurus planiceps, from the secluded river banks and lower mountain slopes of the jungles of Malasia, Borneo, and Sumatra, there remain only 5 rare and endangered species yet unstudied. Although some, including the flat-headed cat, have somewhat distinctive chromosome configurations, all cats thus far karyotyped show 38-chromosome counts, excepting 5 new world "tropicals" which have 36. A pattern of probable feline mutations can be read from the chromosome variations in the different species.