Coumarin C−H Functionalization by Mn(I) Carbonyls : Mechanistic Insight by Ultra-Fast IR Spectroscopic Analysis

Mn(I) C−H functionalization of coumarins provides a versatile and practical method for the rapid assembly of fused polycyclic pyridinium-containing coumarins in a regioselective manner. The synthetic strategy enables application of bench-stable organomanganese reagents in both photochemical- and thermal-promoted reactions. The cyclomanganated intermediates, and global reaction system, provide an ideal testing ground for structural characterization of the active Mn(I) carbonyl-containing species, including transient species observable by ultra-fast time-resolved spectroscopic methods. The thermodynamic reductive elimination product, solely encountered from reaction between alkynes and air-stable organometallic cyclomanganated coumarins, has enabled characterization of a critical seven-membered Mn(I) intermediate, detected by time-resolved infrared spectroscopy, enabling the elucidation of the temporal profile of key steps in the reductive elimination pathway. Quantitative data are provided. Manganated polycyclic products are readily decomplexed by AgBF4, opening-up an efficient route to the formation of π-extended hybrid coumarin-pyridinium compounds

Synthesis and mesomorphic behaviour of novel light-emitting liquid crystals

We report the results of a systematic study of the structure-mesomorphic behaviour relationships of a diverse range of light-emitting liquid crystals, but especially nematic 2,7-disubstituted-9,9-dialkylfluorenes. The dependence of the mesomorphic behaviour and transition temperatures on the nature and length of the terminal chains, the nature, position and number of lateral substituents and the number and nature of aromatic rings with and without heteroatoms in the central core is studied. The results of these studies are used to design polymerizable, light-emitting crystals (reactive mesogens) with a nematic phase having a high clearing point and a melting point below room temperature for facile OLED fabrication. © 2005 Taylor & Francis.Link_to_subscribed_fulltex

Light-emitting fluorene photoreactive liquid crystals for organic electroluminescence

Light-emitting liquid crystals for organic light-emitting diodes (OLEDs) require low-temperature liquid crystal phases for room-temperature processing and a range of molecular energies for electron and hole injection, as well as tunable color and color purity for multicolor OLEDs. We report a number of light-emitting polymerizable liquid crystals (reactive mesogens) based on 2,7-disubstituted-9,9-dialkylfluorene, whose energy levels can be tuned for optimized charge injection and light emission. As a consequence of these systematic property/structure investigations small molecule reactive mesogens have been synthezised, which exhibit low melting points, even below room temperature and nematic phases above room temperature as single components. Many of the molecules retain a supercooled nematic phase on cooling to room temperature. Simple binary eutectic mixtures of reactive mesogens with identical aromatic cores form light-emitting nematic phases at room temperature with a high clearing point to generate a high order parameter. The ionization potential of six-ring fluorene reactive mesogens can be tuned between 4.93 and 5.57 eV by chemical modification of the aromatic cores. Similarly the emission spectrum can be tuned from blue to green. A typical performance for an OLED using such liquid crystalline materials as a cross-linked polymer network is described.Link_to_subscribed_fulltex

Magnet and Button Battery Ingestion in Children: a multicentre observational study of management and outcomes

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Validation of a high-fidelity training model for fetoscopic spina bifida surgery

Open fetal surgery for spina bifida (SB) is safe and effective yet invasive. The growing interest in fetoscopic SB repair (fSB-repair) prompts the need for appropriate training. We aimed to develop and validate a high-fidelity training model for fSB-repair. fSB-repair was simulated in the abdominal cavity and on the stomach of adult rabbits. Laparoscopic fetal surgeons served either as novices (n = 2) or experts (n = 3) based on their experience. Technical performance was evaluated using competency Cumulative Sum (CUSUM) analysis and the group splitting method. Main outcome measure for CUSUM competency was a composite binary outcome for surgical success, i.e. watertight repair, operation time ≤ 180 min and Objective-Structured-Assessment-of-Technical-Skills (OSATS) score ≥ 18/25. Construct validity was first confirmed since competency levels of novices and experts during their six first cases using both methods were significantly different. Criterion validity was also established as 33 consecutive procedures were needed for novices to reach competency using learning curve CUSUM, which is a number comparable to that of clinical fSB-repair. Finally, we surveyed expert fetal surgeons worldwide to assess face and content validity. Respondents (26/49; 53%) confirmed it with ≥ 71% of scores for overall realism ≥ 4/7 and usefulness ≥ 3/5. We propose to use our high-fidelity model to determine and shorten the learning curve of laparoscopic fetal surgeons and retain operative skills

Why do I need it? I am not at risk! Public perceptions towards the pandemic (H1N1) 2009 vaccine

<p>Abstract</p> <p>Background</p> <p>On the 30th September 2009, the pandemic (H1N1) 2009 influenza vaccine was made available to adults and children aged 10 years and over, in Australia. Acceptance of a novel vaccine is influenced by perceptions of risk including risk of infection, risk of death or severe illness and risk of serious vaccine side-effects. We surveyed a sample of residents from Sydney, Australia to ascertain their risk perception, attitudes towards the pandemic and willingness to accept the pandemic (H1N1) 2009 influenza vaccine.</p> <p>Methods</p> <p>We sampled residents using a cross-sectional intercept design during the WHO Phase 6. Members of the public were approached in shopping and pedestrian malls to undertake the survey during September and October 2009. The survey measured perceived risk, seriousness of disease, recent behavioural changes, likely acceptance of the pandemic (H1N1) 2009 vaccine and issues relating to uptake and perceived safety.</p> <p>Results</p> <p>Of the 627 respondents, the majority felt that they had a "very low to low" (332/627, 52.9%) risk of acquiring H1N1. 24.5% (154/627) of respondents believed that the disease would "very seriously or extremely" affect their health. Nearly half (305/627, 48.6%) reported that in response to the "swine flu" outbreak they had undertaken one or more of the investigated behavioural changes. Overall, the self-reported likelihood of accepting vaccination against novel H1N1 was 54.7% (343/627).</p> <p>Conclusions</p> <p>While, most participants did not believe they were at high risk of acquiring pandemic H1N1 2009, over half of the sample indicated that they would accept the vaccine. Participants who were vaccinated against the seasonal influenza were more likely to receive the H1N1 vaccine. Concerns about safety, the possibility of side effects and the vaccine development process need to be addressed.</p