Designing supramolecular liquid-crystalline hybrids from pyrenyl-containing dendrimers and arene ruthenium metallacycles

YesThe association of the arene ruthenium metallacycle [Ru4(p-cymene)4(bpe)2(donq)2][DOS]4 (bpe = 1,2-bis(4-pyridyl)ethylene, donq = 5,8-dioxydo-1,4-naphtoquinonato, DOS = dodecyl sulfate) with pyrenyl-functionalized poly(arylester) dendrimers bearing cyanobiphenyl end-groups is reported. The supramolecular dendritic systems display mesomorphic properties as revealed by polarized optical microscopy, differential scanning calorimetry and small-angle X-ray scattering measurements. The multicomponent nature of the dendrimers and of the corresponding host–guest supramolecules (i.e., end-group mesogens, dendritic core, pyrene unit, aliphatic spacers, and metallacycle) leads to the formation of highly segregated mesophases with a complex multilayered structure due to the tendency of the various constitutive building-blocks to separate in different organized zones. The pyrenyl dendrimers exhibit a multilayered smectic A-like phase, thereafter referred to as LamSmA phase to emphasize this unaccustomed morphology. As for the corresponding Ru4–metallacycle adducts, they self-organize into a multicontinuous thermotropic cubic phase with the Im3̅m space group symmetry. This represents a unique example of liquid-crystalline behavior observed for such large and complex supramolecular host–guest assemblies. Models of their supramolecular organizations within both mesophases are proposed.R.D. thanks the Swiss National Science Foundation (Grant No 200020-140298) for financial support

Interobserver reproducibility in pathologist interpretation of columnar-lined esophagus

Confirmation of endoscopically suspected esophageal metaplasia (ESEM) requires histology, but confusion in the histological definition of columnar-lined esophagus (CLE) is a longstanding problem. The aim of this study is to evaluate interpathologist variability in the interpretation of CLE. Thirty pathologists were invited to review three ten-case sets of CLE biopsies. In the first set, the cases were provided with descriptive endoscopy only; in the second and the third sets, ESEM extent using Prague criteria was provided. Moreover, participants were required to refer to a diagnostic chart for evaluation of the third set. Agreement was statistically assessed using Randolph’s free-marginal multirater kappa. While substantial agreement in recognizing columnar epithelium (K = 0.76) was recorded, the overall concordance in clinico-pathological diagnosis was low (K = 0.38). The overall concordance rate improved from the first (K = 0.27) to the second (K = 0.40) and third step (K = 0.46). Agreement was substantial when diagnosing Barrett’s esophagus (BE) with intestinal metaplasia or inlet patch (K = 0.65 and K = 0.89), respectively, in the third step, while major problems in interpretation of CLE were observed when only cardia/cardia-oxyntic atrophic-type epithelium was present (K = 0.05–0.29). In conclusion, precise endoscopic description and the use of a diagnostic chart increased consistency in CLE interpretation of esophageal biopsies. Agreement was substantial for some diagnostic categories (BE with intestinal metaplasia and inlet patch) with a well-defined clinical profile. Interpretation of cases with cardia/cardia-oxyntic atrophic-type epithelium, with or without ESEM, was least consistent, which reflects lack of clarity of definition and results in variable management of this entity

Fabrication of crystals from single metal atoms

YesMetal nanocrystals offer new concepts for the design of nanodevices with a range of potential applications. Currently the formation of metal nanocrystals cannot be controlled at the level of individual atoms. Here we describe a new general method for the fabrication of multi-heteroatom-doped graphitic matrices decorated with very small, ångström-sized, three-dimensional (3D)-metal crystals of defined size. We irradiate boron-rich precious-metal-encapsulated self-spreading polymer micelles with electrons and produce, in real time, a doped graphitic support on which individual osmium atoms hop and migrate to form 3D-nanocrystals, as small as 15 Å in diameter, within 1 h. Crystal growth can be observed, quantified and controlled in real time. We also synthesize the first examples of mixed ruthenium–osmium 3D-nanocrystals. This technology not only allows the production of ångström-sized homo- and hetero-crystals, but also provides new experimental insight into the dynamics of nanocrystals and pathways for their assembly from single atoms.We thank the Leverhulme Trust (Early Career Fellowship No. ECF-2013-414 to NPEB), the University of Warwick (Grant No. RDF 2013-14 to NPEB), the Swiss National Science Foundation (Grant No. PA00P2_145308 to NPEB and PBNEP2_142949 to APB), the ERC (Grant No. 247450 to PJS), EPSRC (EP/G004897/1 to RKOR, and EP/F034210/1 to PJS) and Science City (AWM/ERDF) for support. We thank the Wellcome Trust (Grant No. 055663/Z/98/Z) for funding the Electron Microscopy Facility, School of Life Sciences, University of Warwick. We also thank COST Action CM1105 for stimulating discussions, Thomas Wilks for supplying the micelle image for Figure 1, and the Australian Synchrotron and the University of Monash for allocation of time on the SAXS/ WAXS beamline and funding. The 2000FX Gatan Orius digital TEM camera used in this research was funded by Science City: Creating and Characterizing Next Generation Advanced Materials, with support from Advantage West Midlands and part funded by the European Regional Development Fund

A systematic review of the evidence for single stage and two stage revision of infected knee replacement

BACKGROUND: Periprosthetic infection about the knee is a devastating complication that may affect between 1% and 5% of knee replacement. With over 79 000 knee replacements being implanted each year in the UK, periprosthetic infection (PJI) is set to become an important burden of disease and cost to the healthcare economy. One of the important controversies in treatment of PJI is whether a single stage revision operation is superior to a two-stage procedure. This study sought to systematically evaluate the published evidence to determine which technique had lowest reinfection rates. METHODS: A systematic review of the literature was undertaken using the MEDLINE and EMBASE databases with the aim to identify existing studies that present the outcomes of each surgical technique. Reinfection rate was the primary outcome measure. Studies of specific subsets of patients such as resistant organisms were excluded. RESULTS: 63 studies were identified that met the inclusion criteria. The majority of which (58) were reports of two-stage revision. Reinfection rated varied between 0% and 41% in two-stage studies, and 0% and 11% in single stage studies. No clinical trials were identified and the majority of studies were observational studies. CONCLUSIONS: Evidence for both one-stage and two-stage revision is largely of low quality. The evidence basis for two-stage revision is significantly larger, and further work into direct comparison between the two techniques should be undertaken as a priority