Peri‐operative cardiac arrest in children as reported to the 7th National Audit Project of the Royal College of Anaesthetists

The 7th National Audit Project of the Royal College of Anaesthetists studied peri‐operative cardiac arrest. An activity survey estimated UK paediatric anaesthesia annual caseload as 390,000 cases, 14% of the UK total. Paediatric peri‐operative cardiac arrests accounted for 104 (12%) reports giving an incidence of 3 in 10,000 anaesthetics (95%CI 2.2–3.3 per 10,000). The incidence of peri‐operative cardiac arrest was highest in neonates (27, 26%), infants (36, 35%) and children with congenital heart disease (44, 42%) and most reports were from tertiary centres (88, 85%). Frequent precipitants of cardiac arrest in non‐cardiac surgery included: severe hypoxaemia (20, 22%); bradycardia (10, 11%); and major haemorrhage (9, 8%). Cardiac tamponade and isolated severe hypotension featured prominently as causes of cardiac arrest in children undergoing cardiac surgery or cardiological procedures. Themes identified at review included: inappropriate choices and doses of anaesthetic drugs for intravenous induction; bradycardias associated with high concentrations of volatile anaesthetic agent or airway manipulation; use of atropine in the place of adrenaline; and inadequate monitoring. Overall quality of care was judged by the panel to be good in 64 (62%) cases, which compares favourably with adults (371, 52%). The study provides insight into paediatric anaesthetic practice, complications and peri‐operative cardiac arrest

Giant Enhancement of Polarization and Strong Improvement of Retention in Epitaxial Ba0.6_{0.6}Sr0.4_{0.4}TiO3_{3}-Based Nanocomposites

In Ba$_{0.6}$Sr$_{0.4}$TiO$_{3}$ (BSTO)-based epitaxial nanocomposite films increased P r values are demonstrated by up to a factor of 3 compared to standard BSTO films. A strongly reduced temperature coefficient of polarization retention is also obtained, i.e., 0.07% °C$^{−1}$ compared to 0.24% °C$^{−1}$ . Piezopoling with only marginal leakage current is also achieved up to 200 °C, the highest temperature studied. The origin of the improved performance is the incorporation of Sm$_{2}$O$_{3}$ nanopillars in the films which acted as stiff vertical nanoscaffolds, inducing a strong tetragonal distortion in the BSTO (up to 1.033(7) in terms of the out-of-plane/in-plane lattice dimensions). The films have comparable performance to industry-standard Pb(Zr,Ti)O$_{3}$ films, at the same time as being Pb-free

Lead-Free Relaxor Thin Films with Huge Energy Density and Low Loss for High Temperature applications

We report record energy storage density (>80 J·cm-3) in Pb-free relaxor ferroelectrics based on Mn-doped BiFeO3-BaTiO3 thin films. Rapid interval deposition was used to impose layer-by-layer growth improving crystallinity and lowering unwanted defects concentrations. The growth and Mn doping produced an order of magnitude lower leakage, with strongly reduced dielectric loss (from room temperature to >300 °C, and 100 Hz to 1 MHz), e.g. by a factor of 5 at 225 °C and 25 kHz. At room temperature (RT), the dielectric breakdown strength increased by a factor of 1.5 to >3000 kV·cm-1 while the dielectric constant remained flat, at ∼1000 from RT to 350 °C. The films perform better than competing materials (e.g. PZT and SrTiO3-based) while being Pb-free and while operating up to 350°C, which SrTiO3-based systems do not. Our work gives considerable promise for high energy and power density capacitors for harsh environments.We acknowledge funding support from EPSRC grants EP/N004272/1, EP/M000524/1, and EP/L011700/1, the Leverhulme Trust grant RPG-2015-017, the Winton Foundation and Deregallera Ltd., U.K

Nanoengineering room temperature ferroelectricity into orthorhombic SmMnO₃ films

Orthorhombic RMnO3 (R = rare-earth cation) compounds are type-II multiferroics induced by inversion-symmetry-breaking of spin order. They hold promise for magneto-electric devices. However, no spontaneous room-temperature ferroic property has been observed to date in orthorhombic RMnO3. Here, using 3D straining in nanocomposite films of (SmMnO3)0.5((Bi,Sm)2O3)0.5, we demonstrate room temperature ferroelectricity and ferromagnetism with TC,FM ~ 90 K, matching exactly with theoretical predictions for the induced strain levels. Large in-plane compressive and out-of-plane tensile strains (−3.6% and +4.9%, respectively) were induced by the stiff (Bi,Sm)2O3 nanopillars embedded. The room temperature electric polarization is comparable to other spin-driven ferroelectric RMnO3 films. Also, while bulk SmMnO3 is antiferromagnetic, ferromagnetism was induced in the composite films. The Mn-O bond angles and lengths determined from density functional theory explain the origin of the ferroelectricity, i.e. modification of the exchange coupling. Our structural tuning method gives a route to designing multiferroics

Strong pinning at high growth rates in rare earth barium cuprate (REBCO) superconductor films grown with liquid-assisted processing (LAP) during pulsed laser deposition

Funder: SuNAM Co. Ltd.Abstract We present a simple liquid-assisted processing (LAP) method, to be used in situ during pulsed laser deposition growth to give both rapid growth rates (50 Hz deposition leading to >250 nm min−1 with a single plume) and strong pinning (improved ×5–10 at 30 K and below, over plain standard YBCO films grown at similar rates). Achieving these two important features simultaneously has been a serious bottleneck to date and yet for applications, it is critical to overcome it. The new LAP method uses a non-stoichiometric target composition, giving rise to a small volume fraction of liquid phase during film growth. LAP enhances the kinetics of the film growth so that good crystalline perfection can be achieved at up to 60× faster growth rates than normal, while also enabling artificial pinning centres to be self-assembled into fine nanocolumns. In addition, LAP allows for RE mixing (80% of Y with 20% of Yb, Sm, or Yb + Sm), creating effective point-like disorder pinning centres within the rare earth barium cuprate lattice. Overall, LAP is a simple method for use in pulsed laser deposition, and it can also be adopted by other in situ physical or vapour deposition methods (i.e. MOCVD, evaporation, etc) to significantly enhance both growth rate and performance.Grant from SuNAM Co. Ltd. Henry Royce Institute Equipment Grant: EP/P024947/

Strong pinning at high growth rates in rare earth barium cuprate (REBCO) superconductor films grown with liquid-assisted processing (LAP) during pulsed laser deposition

Funder: SuNAM Co. Ltd.Abstract: We present a simple liquid-assisted processing (LAP) method, to be used in situ during pulsed laser deposition growth to give both rapid growth rates (50 Hz deposition leading to >250 nm min−1 with a single plume) and strong pinning (improved ×5–10 at 30 K and below, over plain standard YBCO films grown at similar rates). Achieving these two important features simultaneously has been a serious bottleneck to date and yet for applications, it is critical to overcome it. The new LAP method uses a non-stoichiometric target composition, giving rise to a small volume fraction of liquid phase during film growth. LAP enhances the kinetics of the film growth so that good crystalline perfection can be achieved at up to 60× faster growth rates than normal, while also enabling artificial pinning centres to be self-assembled into fine nanocolumns. In addition, LAP allows for RE mixing (80% of Y with 20% of Yb, Sm, or Yb + Sm), creating effective point-like disorder pinning centres within the rare earth barium cuprate lattice. Overall, LAP is a simple method for use in pulsed laser deposition, and it can also be adopted by other in situ physical or vapour deposition methods (i.e. MOCVD, evaporation, etc) to significantly enhance both growth rate and performance

Strong pinning at high growth rates in rare earth barium cuprate (REBCO) superconductor films grown with liquid-assisted processing (LAP) during pulsed laser deposition

Funder: SuNAM Co. Ltd.Abstract: We present a simple liquid-assisted processing (LAP) method, to be used in situ during pulsed laser deposition growth to give both rapid growth rates (50 Hz deposition leading to >250 nm min−1 with a single plume) and strong pinning (improved ×5–10 at 30 K and below, over plain standard YBCO films grown at similar rates). Achieving these two important features simultaneously has been a serious bottleneck to date and yet for applications, it is critical to overcome it. The new LAP method uses a non-stoichiometric target composition, giving rise to a small volume fraction of liquid phase during film growth. LAP enhances the kinetics of the film growth so that good crystalline perfection can be achieved at up to 60× faster growth rates than normal, while also enabling artificial pinning centres to be self-assembled into fine nanocolumns. In addition, LAP allows for RE mixing (80% of Y with 20% of Yb, Sm, or Yb + Sm), creating effective point-like disorder pinning centres within the rare earth barium cuprate lattice. Overall, LAP is a simple method for use in pulsed laser deposition, and it can also be adopted by other in situ physical or vapour deposition methods (i.e. MOCVD, evaporation, etc) to significantly enhance both growth rate and performance