Puddle formation, persistent gaps, and non-mean-field breakdown of superconductivity in overdoped (Pb,Bi)2Sr2CuO6+{\delta}

The cuprate high-temperature superconductors exhibit many unexplained electronic phases, but it was often thought that the superconductivity at sufficiently high doping is governed by conventional mean-field Bardeen-Cooper-Schrieffer (BCS) theory[1]. However, recent measurements show that the number of paired electrons (the superfluid density) vanishes when the transition temperature Tc goes to zero[2], in contradiction to expectation from BCS theory. The origin of this anomalous vanishing is unknown. Our scanning tunneling spectroscopy measurements in the overdoped regime of the (Pb,Bi)2Sr2CuO6+{\delta} high-temperature superconductor show that it is due to the emergence of puddled superconductivity, featuring nanoscale superconducting islands in a metallic matrix[3,4]. Our measurements further reveal that this puddling is driven by gap filling, while the gap itself persists beyond the breakdown of superconductivity. The important implication is that it is not a diminishing pairing interaction that causes the breakdown of superconductivity. Unexpectedly, the measured gap-to-filling correlation also reveals that pair-breaking by disorder does not play a dominant role and that the mechanism of superconductivity in overdoped cuprate superconductors is qualitatively different from conventional mean-field theory

Base-free anaerobic Cu(II) catalysed aryl-nitrogen bond formations

Graphical abstractThe Cu(II) catalysed coupling of arylboronic acids with imidazole can be performed at ambient temperature without the need for base or dioxygen. The presence of water however is essential for the reaction to proceed.AbstractThe coupling of arylboronic acids with imidazole in the presence of binuclear bis-l-hydroxy copper(II) complexes is reported. The reactions can be performed in air as well as under nitrogen atmosphere. Reactions are carried out at ambient temperature without the need for base. The presence of water is essential for the reaction to proceed. Ligand effects on the yield and selectivity are reported

Comparison of two instruments measuring carotid-femoral pulse wave velocity: Vicorder versus SphygmoCor

Background The carotid-femoral pulse wave velocity (PWVcf) is used as an indicator of arterial stiffness. It is often measured using applanation tonometry, for instance with the SphygmoCor. In young children, this method is difficult to perform. Therefore, techniques are needed that are less dependent on patient compliance. The Vicorder device uses the oscillometric technique to measure the PWVcf and is thought to be less time consuming and less dependent on operator skills. Objective To compare the PWVcf measured by an extensively used device (SphygmoCor) and the Vicorder in adults initially. Methods Thirty-eight healthy volunteers (20 men, mean age 48 +/- 13.1 years) participated in this cross-sectional study. The PWVcf was assessed twice using the SphygmoCor and the Vicorder by a single investigator during one visit. Intra-rater reproducibility of each instrument and comparison between the two instruments were assessed by the Bland-Altman method. Results The mean difference (95% confidence interval) between repeated measurements was 0.09 (-0.20 to 0.38) m/s and 0.24 (-0.55 to 1.03) m/s, for the SphygmoCor and Vicorder, respectively. The Limits of Agreement (LoA) were -1.53 to 1.71 m/s and -4.24 to 4.72 m/s, for the SphygmoCor and Vicorder, respectively. The mean PWVcf measured by the Vicorder was 0.58 (-0.20 to 1.35) m/s higher than the PWVcf measured by the SphygmoCor. The LoA between the two instruments were -3.50 to 4.66 m/s. Conclusion The LoA of both instruments exceed a value of 1.5 m/s. The LoA of the Vicorder PWVcf measurements are considered too wide for using this technique reliably in adults or in children. J Hypertens 28: 1687-1691 (c) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkin

Direct evidence for Cooper pairing without a spectral gap in a disordered superconductor above T c

The idea that preformed Cooper pairs could exist in a superconductor at temperatures higher than its zero-resistance critical temperature (Tc) has been explored for unconventional, interfacial, and disordered superconductors, but direct experimental evidence is lacking. We used scanning tunneling noise spectroscopy to show that preformed Cooper pairs exist up to temperatures much higher than Tc in the disordered superconductor titanium nitride by observing an enhancement in the shot noise that is equivalent to a change of the effective charge from one to two electron charges. We further show that the spectroscopic gap fills up rather than closes with increasing temperature. Our results demonstrate the existence of a state above Tc that, much like an ordinary metal, has no (pseudo)gap but carries charge through paired electrons

Increased prevalence of cardiovascular and autoimmune diseases in periodontitis patients: a cross-sectional study

Background: Associations between periodontitis and cardiovascular and autoimmune diseases are most often assessed in patients with a particular cardiovascular or autoimmune disease. To prevent selection bias, this study assesses the existence of associations between periodontitis and cardiovascular and autoimmune diseases in patients attending a dental or periodontal clinic. Methods: Data were collected from 1,276 randomly selected dental records from patients attending a dental (n = 588) or periodontal (n = 688) clinic. Data on the prevalence of cardiovascular and autoimmune diseases were obtained from a validated health questionnaire. Data on the presence of periodontitis were taken from patients' dental records. Results: In uncontrolled analyses, the prevalence of hypertension, diabetes mellitus (DM), and rheumatoid arthritis (RA) is significantly increased in patients with periodontitis. Controlled for confounding, periodontitis was associated with DM, with an odds ratio of 4 (1.03 to 15.3), in the dental clinic. DM was not associated with periodontitis in periodontal clinics. Hypertension does not seem to be associated with periodontitis when controlling for confounders. Periodontitis may be associated with RA in both clinic types. Conclusions: The increased prevalence of cardiovascular and autoimmune diseases among patients with periodontitis attending dental or periodontal clinics may, at least in part, be influenced by confounding. However, the increased prevalence of DM and RA in patients with periodontitis could not be explained by confounding. J Periodontol 2010;81:1622-1628