Search

This work presents a detailed microstructure and texture study of various hydrided Zircaloy-4 materials by neutron diffraction and microscopy. The results show that the precipitated δ-ZrH1.66 generally follows the δ(111)//α(0001) and δ[110]//α[1120] orientation relationship with the α-Zr matrix. The δ-hydride displays a weak texture that is determined by the texture of the α-Zr matrix, and this dependence essentially originates from the observed orientation correlation between α-Zr and δ-hydride. Neutron diffraction line profile analysis and highresolution transmission electron microscopy observations reveal a significant number of dislocations present in the δ-hydride, with an estimated average density one order of magnitude higher than that in the α-Zr matrix, which contributes to the accommodation of the substantial misfit strains associated with hydride precipitation in the α-Zr matrix. The present observations provide an insight into the behaviour of δ-hydride precipitation in zirconium alloys and may help with understanding the induced embrittling effect of hydrides. [ABSTRACT FROM AUTHOR]

This work presents a detailed microstructure and texture study of various hydrided Zircaloy-4 materials by neutron diffraction and microscopy. The results show that the precipitated δ-ZrH1.66 generally follows the δ(111)//α(0001) and δ[110]//α[1120] orientation relationship with the δ-Zr matrix. The δ-hydride displays a weak texture that is determined by the texture of the α-Zr matrix, and this dependence essentially originates from the observed orientation correlation between α-Zr and δ-hydride. Neutron diffraction line profile analysis and highresolution transmission electron microscopy observations reveal a significant number of dislocations present in the δ-hydride, with an estimated average density one order of magnitude higher than that in the α-Zr matrix, which contributes to the accommodation of the substantial misfit strains associated with hydride precipitation in the α-Zr matrix. The present observations provide an insight into the behaviour of δ-hydride precipitation in zirconium alloys and may help with understanding the induced embrittling effect of hydrides. [ABSTRACT FROM AUTHOR]

The study examines fatigue in elite soccer played in hot conditions. High-profile soccer players ( n=20) were studied during match play at ∼31 °C. Repeated sprint and jump performances were assessed in rested state and after a game and activity profile was examined. Additionally, heart rate (HR), blood lactate, muscle temperature and body mass changes were determined. Repeated sprint and jump performances were reduced ( P<0.05) by 2.6% and 8.2%, respectively, after the game. The fatigue index in the repeated sprint test was 6.0±0.7% after the game compared with 1.7±1.0% at rest ( P<0.05). High-intensity running was 57±4% lower ( P<0.05) during the last 15-min interval of the game compared with the first 15-min period. No differences were observed in mean HR or blood lactates between halves. Muscle temperature was 40.5±0.4 °C after the first half, which was 0.8±0.2 °C higher ( P<0.05) than after the second half. Net fluid loss during the game was >2% of the body mass. Correlations were observed between net-fluid loss and repeated sprint test fatigue index after the game ( r=0.73, P<0.05) and Yo-Yo intermittent recovery, level 1 test performance and high-intensity running during the final 15 min of the game ( r=0.51, P<0.05). The study provides direct evidence of compromised repeated sprint and jump performances induced by soccer match play and pronounced reduction in high-intensity running toward the end of an elite game played in a hot environment. This fatigue could be associated training status and hyperthermia/dehydration. [ABSTRACT FROM AUTHOR]

ENGIN-X, a new time-of-flight (TOF) neutron diffractometer optimized to measure elastic strains at precise locations in bulky specimens recently commissioned at the ISIS Facility in the Rutherford Laboratory, UK, is described. Fast counting times, together with a flexible and accurate definition of the instrumental gauge volume are the main requirements of neutron strain scanning and have been addressed on ENGIN-X through the design of a novel TOF diffractometer with a tuneable resolution and interchangeable radial collimators. Further, the routine operation of the instrument has been optimized by creating a virtual instrument, i.e. a three-dimensional computer representation of the diffractometer and samples, which assists in the planning and execution of experiments. On comparing ENGIN-X with its predecessor ENGIN, a 25× gain in performance is found, which has allowed the determination of stresses up to 60 mm deep in steel specimens. For comparison with constant-wavelength diffractometers, special attention has been paid to the absolute number of counts recorded during the experiments. A simple expression is presented for the estimation of counting times in TOF neutron strain scanning experiments. [ABSTRACT FROM AUTHOR]

The objective of this paper was to evaluate romifidine as a pre-medicant in dogs prior to propofol–isoflurane anaesthesia, and to compare it with medetomidine. For this, eight healthy dogs were anaesthetised. Each dog received three pre-anaesthetic protocols: R40 (romifidine, 40 μg/kg, IV), R80 (romifidine, 80 μg/kg, IV) or MED (medetomidine, 10 μg/kg, IV). Induction of anaesthesia was delivered with propofol and maintained with isoflurane. The following variables were studied before sedative administration and 10 min after sedative administration: heart rate (HR), mean arterial pressure (MAP), systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) and respiratory rate (RR). During maintenance, the following variables were recorded at 5-min intervals: HR, MAP, SAD, DAP, arterial oxygen saturation (SpO2), end-tidal CO2(EtCO2), end-tidal concentration of isoflurane (EtISO) required for maintenance of anaesthesia and tidal volume (TV). Time to extubation, time to sternal recumbency and time to standing were also registered. HR and RR experimented a significantly decreased during sedation in all protocols respect to baseline values. Mean HR, MAP, SAP, DAP, SpO2, EtCO2, and TV during anaesthesia were similar for the three protocols. End tidal of isoflurane concentration was statistically similar for all protocols. Recovery time for R40 was significantly shorter than in R80 and MED. The studied combination of romifidine, propofol and isoflurane appears to be an effective drug combination for inducing and maintaining general anaesthesia in healthy dogs. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate dexmedetomidine as a premedicant in dogs prior to propofol–desflurane anaesthesia, and to compare it with medetomidine. Six healthy dogs were anaesthetized. Each dog received intravenously (i.v.) five preanaesthetic protocols: D1 (dexmedetomidine, 1 μg/kg, i.v.), D2 (dexmedetomidine, 2 μg/kg, i.v.), M1 (medetomidine, 1 μg/kg, i.v.), M2 (medetomidine, 2 μg/kg, i.v.), or M4 (medetomidine, 4 μg/kg, i.v.). Anaesthesia was induced with propofol (2.3–3.3 mg/kg) and maintained with desflurane. The following variables were studied: heart rate (HR), mean arterial pressure, systolic arterial pressure, diastolic arterial pressure, respiratory rate (RR), arterial oxygen saturation, end-tidal CO2, end-tidal concentration of desflurane (EtDES) required for maintenance of anaesthesia and tidal volume. Arterial blood pH (pHa) and arterial blood gas tensions (PaO2, PaCO2) were measured during anaesthesia. Time to extubation, time to sternal recumbency and time to standing were also recorded. HR and RR decreased significantly during sedation in all protocols. Cardiorespiratory variables during anaesthesia were statistically similar for all protocols. EtDES was significantly different between D1 (8.1%) and D2 (7.5%), and between all doses of medetomidine. Desflurane requirements were similar for D1 and M2, and for D2 and M4 protocols. No statistical differences were observed in recovery times. The combination of dexmedetomidine, propofol and desflurane appears to be effective for induction and maintenance of general anaesthesia in healthy dogs. [ABSTRACT FROM AUTHOR]

Non-destructive neutron diffraction techniques were applied to determine composition and microstructure data, and hence to derive information on manufacturing techniques of Picenum bronze artefacts. Furthermore, texture analyses were carried out on standards and suitable ancient artefacts to investigate their potential role in archaeometallurgical studies. This is a first step towards an overall characterization of the bronze collection of the Marches National Museum of Archaeology, Italy, and the analytical demonstration of relations with and differences compared to Etruscan metallurgy. The work is also an example application of the powerful non-destructive archaeometrical approaches provided by time-of-flight neutron diffraction. [ABSTRACT FROM AUTHOR]

Compares the cardiopulmonary effects produced by romifidine and medetomidine when used as preanesthetic agents before general anesthesia with propofol and sevoflurane in dogs. Dose-dependent cardiovascular effects of romifidine on dogs; Variable effect of sevoflurane on dogs' heart rate; Characteristics of the drugs.

The feasibility of both high spatial and strain resolution is demonstrated using high-energy X-rays between 100 and 300 keV on beamline ID15A at the ESRE The data analysis was performed using a multiple-peak Pawley-type refinement on the recorded spectra. An asymmetric peak profile was necessary in order to obtain a point-to-point uncertainty of 10-5. The measurements have been validated with complementary techniques or reference data. [ABSTRACT FROM AUTHOR]

A fluorescein angiography method was developed to compare the onset and the total duration of the fluorangiographic phases between three anaesthetic protocols in six healthy mixed-breed dogs. The animals were anaesthetized three times. Each dog received, as pre-anaesthetic protocol, atropine (10 μg/kg intramuscularly), and as a sedative, romifidine (80 μg/kg intravenously). Fifteen minutes later, induction of anaesthesia was delivered with propofol (1 mg/kg intravenously) and maintained either with sevoflurane (SEVO group), isoflurane (ISO group) or halothane (HAL group) for 30 min in all cases. Some angiographic, cardiovascular and respiratory variables were registered during the procedure. Recovery times were also registered. Angiographic variables recorded were: onset of the arterial phase (TA), onset of the arteriovenous phase (TAV), onset of the venous phase (TV), complete arterial phase duration (I1), complete arteriovenous phase duration (I2) and I1 plus I2 (I3). Mean heart rate, mean arterial pressure, systolic arterial pressure, diastolic arterial pressure, respiratory rate, tidal volume, arterial oxygen saturation and end-tidal CO2 during SEVO and ISO anaesthesia, were similar in dogs. Minute ventilation and rectal temperature were higher in dogs with SEVO than ISO. HAL produced higher arterial pressures and a lower arterial oxygen saturation than ISO and SEVO. Mean respiratory rate, rectal temperature and minute ventilation were higher in HAL. Pulse rate, end-tidal CO2 and tidal volume were similar in the dogs of the three groups. No differences in recovery times were found. The fluorescein angiographic times were within the normal range. There were no significant differences between protocols in I1, I2 or I3. HAL produced a significant increase of all temporal variables (TA, TAV and TV) when compared with ISO; TA was higher in HAL than SEVO-treated dogs. All protocols appear to be safe and effective for inducing and maintaining general anaesthesia in healthy dogs for performing fluorescein angiography. [ABSTRACT FROM AUTHOR]

Focuses on a study which proposed a three-parameter profile to describe the sharp discontinuity in the neutron cross section of polycrystalline materials called Bragg edge. Basic concepts; Calibration; Optimal configuration.