Hyper-expanded interlayer separations in superconducting barium intercalates of FeSe.

Intercalation of Ba in ß-FeSe by ammonothermal synthesis results in the formation of different superconducting phases with interlayer distance ranging between 8.4 and 13.1 Å. The values of Tc are primarily dependent on Ba content, and are further modulated by the interlayer spacing through facile intercalation and deintercalation of ammonia.

Nature of conductivity in SrSiO3-based fast ion conductors.

In this paper we report the preparation and characterization of Sr1-xNaxSiO3-0.5x samples, recently proposed as oxide ion conductors. We show that Na-doping unlikely takes place in the silicate phase, and that a secondary glassy phase is at the origin of the transport properties, thereby suggesting that the conductivity is due only to a limited extent to oxide ion migration in the crystalline system.

Labeling interacting configurations through an analysis of excitation dynamics in a resonant photoemission experiment: the case of rutile TiO2.

A detailed study of resonant photoemission at Ti L(2,3) edges of insulating rutile TiO(2-x) thin film is presented. Pure TiO(2) resonating structures, defect-related resonances, resonant Raman-Auger and normal LVV Auger emissions are tracked, including an unpredicted two-hole correlated satellite below the non-bonding part of the valence band. The analysis of excitation dynamics unambiguously addresses the origin of these features and, in particular, the extent of charge transfer effects on the Ti-O bonding in the valence band of rutile, disclosing further applications to the more general case of, formally, d(0) oxides.

Vibrational spectrum of solid picene (C22H14).

Recently, Mitsuhashi et al observed superconductivity with a transition temperature up to 18 K in potassium doped picene (C(22)H(14)), a polycyclic aromatic hydrocarbon compound (Mitsuhashi et al 2010 Nature 464 76). Theoretical analysis indicates the importance of electron-phonon coupling in the superconducting mechanisms of these systems, with different emphasis on inter- and intra-molecular vibrations, depending on the approximations used. Here we present a combined experimental and ab initio study of the Raman and infrared spectrum of undoped solid picene, which allows us to unambiguously assign the vibrational modes. This combined study enables the identification of the modes which couple strongly to electrons and hence can play an important role in the superconducting properties of the doped samples.

Temperature-dependent local structure of NdFeAsO(1-x)F(x) system using arsenic K-edge extended x-ray absorption fine structure.

Local structure of NdFeAsO(1-x)F(x) (x = 0.0, 0.05, 0.15 and 0.18) high temperature iron-pnictide superconductor system is studied using arsenic K-edge extended x-ray absorption fine structure measurements as a function of temperature. Fe-As bond length shows only a weak temperature and F-substitution dependence, consistent with the strong covalent nature of this bond. The temperature dependence of the mean square relative displacements of the Fe-As bond length are well described by the correlated Einstein model for all the samples, but with different Einstein temperatures for the superconducting and non-superconducting samples. The results indicate distinct local Fe-As lattice dynamics in the superconducting and non-superconducting iron-pnictide systems.

Local structural studies of Ba(1-x)K(x)Fe2As2 using atomic pair distribution function analysis.

Systematic local structural studies of the Ba(1-x)K(x)Fe(2)As(2) system are undertaken at room temperature using atomic pair distribution function analysis. The local structure of the Ba(1-x)K(x)Fe(2)As(2) is found to be well described by the long-range structure extracted from diffraction experiments, but with anisotropic atomic vibrations of the constituent atoms (U11 = U22 not equal U33). The crystal unit cell parameters, the FeAs(4) tetrahedral angle and the pnictogen height above the Fe-plane are seen to show systematic evolution with K doping, underlining the importance of the structural changes, in addition to the charge doping, in determining the properties of Ba(1-x)K(x)Fe(2)As(2).

Synthesis and characterization of pure and doped (Na, Ca, Sr) nanograined LaMnO3 magnetoresistive ceramics.

Pure and Na, Ca, and Sr doped lanthanum manganites (LaMnO3, La0.85Na0.15MnO3, La0.7Ca0.3 MnO3, La0.7Sr0.3MnO3) were prepared in form of bulk nano-structured materials through a two-step process. Nanometric powders were synthesized by the Pechini method and subsequently densified by Spark Plasma Sintering at 1273 K for 5 minutes under a pressure of 140 MPa. The method allowed the preparation of single phase manganites with a theoretical density above 98% together with a very limited growth of the grain size. Grain sizes below 70 nm were obtained for all materials except La0.85Na0.15MnO3 which showed a much larger grain size. Curie temperatures (Tc) and magnetoresistivity properties of the samples were measured by a Superconducting Quantum Interference Device (SQUID). The decrease in the resistivity below Tc occurred in a much wider range of temperature compared to ceramics having micron-size grains.

Changes in minimal alveolar concentration of isoflurane following treatment with medetomidine and tiletamine/zolazepam, epidural morphine or systemic buprenorphine in pigs.

The aim of this study was to determine the changes in minimal alveolar concentration (MAC) of isoflurane after treatment with medetomidine and tiletamine/zolazepam (MTZ), epidural morphine or systemic buprenorphine in 11 healthy crossbred pigs. The first part of this study was to measure the baseline values in pigs induced with isoflurane (5%) by face mask and maintained with isoflurane in air and oxygen for 2 h (ISO). Baseline isoflurane MAC was determined using mechanical stimulation. Thereafter, each pig was randomly chosen for a crossover test in which the same animal received three different treatments with at least one week in between treatments. The three treatments were as follows: induction of anaesthesia with medetomidine (0.05 mg kg(-1)) and tiletamine/zolazepam (2.5 mg kg(-1) each) given intramuscularly (MTZ); MTZ followed by epidural morphine (0.1 mg kg(-1); MTZ/M); and MTZ followed by intramuscular buprenorphine (0.1 mg kg(-1); MTZ/B). All pigs were maintained with isoflurane in oxygen and air for 2 h and their lungs were mechanically ventilated. The end-tidal isoflurane concentration, respiratory rate, inspiratory and expiratory O2 and CO2 concentrations, heart rate (HR) and arterial blood pressure were recorded every 10 min. Arterial blood gases were analysed every 20 min. Among the treatment groups, differences in isoflurane MAC were tested using GLM and Tukey's method for further comparison; P < 0.05 was adopted as significant. Isoflurane MAC was 1.9 +/- 0.3%. MTZ reduced isoflurane MAC to 0.6 +/- 0.1%. Additional morphine or buprenorphine reduced the MTZ isoflurane MAC further to 0.4 +/- 0.2 and 0.3 +/- 0.1%, respectively. During MTZ, MTZ/M and MTZ/B mean arterial blood pressure was higher and the alveolar-arterial oxygen tension difference was lower compared with ISO. In conclusion, induction of anaesthesia with MTZ reduced the isoflurane MAC in pigs by 68%. Additional epidural morphine or systemic buprenorphine decreased MTZ isoflurane MAC by 33 and 50%, respectively.

Evidence of a pressure-induced metallization process in monoclinic VO2.

Raman and combined infrared transmission and reflectivity measurements were carried out at room temperature (RT) on monoclinic VO2 over the 0-19 GPa and 0-14 GPa pressure ranges. Both lattice dynamics and optical gap show a remarkable stability up to P* approximately 10 GPa whereas subtle modifications of V ion arrangements within the monoclinic lattice, together with the onset of a metallization process via band gap filling, are observed for P >P*. Differently from P=0, where the VO2 metallic phase is found only in conjunction with the rutile structure above 340 K, a new RT metallic phase within a monoclinic structure appears accessible in the high pressure regime.

Effects of epidural morphine and transdermal fentanyl analgesia on physiology and behaviour after abdominal surgery in pigs.

The objective of this work was to evaluate the physiological and behavioural effects of opioid analgesic treatment in pigs subjected to abdominal surgery. Ten Swedish Landrace x Yorkshire pigs (20 +/- 4 kg b.w.) were submitted for intestinal cannulation. The pigs were allocated into two groups during one preoperative, one surgical and two postoperative days. All pigs were anaesthetized with medetomidine, tiletamine and zolazepam. One group was treated with epidural morphine (0.1 mg/kg) preoperatively, and transdermal fentanyl patches (50 microg/kg/h) were applied behind the ear immediately after surgery. The other group received epidural saline (equivalent volume) and placebo patches. All pigs were regularly weighed and clinically examined and repeated blood samples were analysed for serum concentrations of cortisol, beta-endorphin and fentanyl. Pre- and postoperative behaviours were evaluated by a swine specialist blinded to the treatment, three times a day, and were also videotape recorded for a total of 84 h per pig. No differences in behaviour were noted by the observer. During the first postoperative 12 h, treated pigs did not differ in activity compared with preoperative recordings, while untreated pigs were found to be less active. The treated group started to show interest in eating immediately after anaesthesia recovery, whereas the placebo group did not. During the 12-60 h postoperative period, the treated group had lower activity levels compared with the preoperative levels, which were similar to those in the placebo group. Treated pigs gained 0.5 +/- 0.2 kg during the subsequent two postoperative days, whereas the untreated pigs lost weight throughout the experiment. Cortisol concentration differed immediately after the surgery: Group P had 325 +/- 120 nmol/L and Group M 159 +/- 49 nmol/L. beta-endorphin concentration did not differ between groups. The highest serum fentanyl concentration (0.37 +/- 0.3 ng/mL) was measured 24 h postoperatively. Preoperative epidural morphine in combination with postoperative transdermal fentanyl resulted in earlier return to normal activity levels and an immediate weight gain after surgery.

The effect of transdermal delivery of fentanyl on activity in growing pigs.

Recently, decreased activity levels have been observed in pigs treated postoperatively with transdermal delivery of fentanyl (TD-fentanyl) after isoflurane anaesthesia. Whether the change in behaviour is related to opioid-induced sedation or to insufficient pain relief remains to be investigated. This study was therefore undertaken to evaluate the effect of TD-fentanyl 50 microg h(-1) on the activity level with and without isoflurane anaesthesia. Eight pigs (25.4 +/- 5.2 kg) were submitted to a cross-over study and given two treatments; 1) fentanyl patch applied after 30 minutes of anaesthesia (treatment A/F) and 2) fentanyl patch without anaesthesia (treatment F). The pigs' behaviour was observed from a video recording instantaneously every 10 minutes for 24 h before treatments and up to 72 h after the patch attachment. Venous blood samples were taken 1, 6, 12, 24, 48 and 72 h after the patch application. The behaviour recordings showed that TD-fentanyl did not produce sedation in any pig. No differences were found between the two treatments in activity level, weight gain or serum fentanyl concentration. This concentration measured after 24 h was 0.27 +/- 0.11 ng ml(-1) and 0.47 +/- 0.40 ng ml(-1) in the A/F and F group, respectively. In conclusion, transdermal delivery of 50 microg h(-1) fentanyl did not cause inactivity in growing pigs. However, the large variations in serum fentanyl concentration indicate that drug absorption from transdermal patches is unpredictable and sometimes deficient.