First-principles study of lithium aluminosilicate glass scintillators.

Radiation sensors are an important enabling technology in several fields, such as medicine, scientific research, energy, defence, meteorology, and homeland security. Glass-based scintillators have been in use for more than 50 years and offer many benefits, including their ability to respond to different types of radiation, and to be readily formed into various shapes. There is, however, the prospect to develop new and improved glass scintillators, with low self-absorption, low refractive indices, and high radiative recombination rates. To investigate the factors limiting the improvement of glass scintillator properties, this work provides insight from atomic scale simulations of the cerium-doped lithium aluminosilicate (SiO2-Al2O3-MgO-Li2O-Ce2O3) glass scintillator system. Three glass compositions were studied using molecular dynamics and density functional theory to investigate the effect of the ratio (with RAl/M = [0.1, 0.8 and 1.2]) on the structural and electronic properties. For a ratio RAl/M > 1, it has been shown that glasses with increased polymerization allow for more effective incorporation of Ce3+ cations. The structural analysis also showed that the bond order of Al-O can be affected in the presence of a lithium-rich environment. Electronic density of states and Bader charge analysis indicate a decline in the population of localized trapping states with increasing RAl/M. This suggests a higher probability of radiative recombination which can increase the photon yield of these scintillators. These findings provide valuable guidance for optimizing Li-glasses in neutron detection systems by highlighting the intricate challenges.

Determination of Debye temperatures and Lamb-Mössbauer factors for LnFeO3 orthoferrite perovskites (Ln = La, Nd, Sm, Eu, Gd).

Lanthanide orthoferrites have wide-ranging industrial uses including solar, catalytic and electronic applications. Here a series of lanthanide orthoferrite perovskites, LnFeO3 (Ln = La; Nd; Sm; Eu; Gd), prepared through a standard stoichiometric wet ball milling route using oxide precursors, has been studied. Characterisation through x-ray diffraction and x-ray fluorescence confirmed the synthesis of phase-pure or near-pure LnFeO3 compounds. 57Fe Mössbauer spectroscopy was performed over a temperature range of 10 K-293 K to observe hyperfine structure and to enable calculation of the recoil-free fraction and Debye temperature (θ D) of each orthoferrite. Debye temperatures (Ln = La 474 K; Nd 459 K; Sm 457 K; Eu 452 K; Gd 473 K) and recoil-free fractions (Ln = La 0.827; Nd 0.817; Sm 0.816; Eu 0.812; Gd 0.826) were approximated through minimising the difference in the temperature dependent experimental centre shift and theoretical isomer shift, by allowing the Debye temperature and isomer shift values to vary. This method of minimising the difference between theoretical and actual values yields Debye temperatures consistent with results from other studies determined through thermal analysis methods. This displays the ability of variable-temperature Mössbauer spectroscopy to approximate Debye temperatures and recoil-free fractions, whilst observing temperature induced transitions over the temperature range observed. X-ray diffraction and Rietveld refinement show an inverse relationship between FeO6 octahedral volume and approximated Debye temperatures. Raman spectroscopy show an increase in the band positions attributed to soft modes of Ag symmetry, Ag(3) and Ag(5) from La to GdFeO3 corresponding to octahedral rotations and tilts in the [0 1 0] and [1 0 1] planes respectively.

Management and outcomes of isolated paediatric tibial spine fractures.

Paediatric fractures of the tibial spine are relatively rare and controversy remains around how these injuries are best managed (Gans et al., 2014; Hargrove et al., 2004). Consequently most non-specialised paediatric units have limited experience of managing these injuries. This study aims to review the management and outcomes of isolated paediatric tibial spine fractures in a tertiary paediatric orthopaedic centre between 2008 and 2016. Data were collected on patient demographics, mechanism of injury, imaging, Meyers and McKeever grade of injury (Meyers and McKeever), management and outcomes, including Cincinnati and Lysholm-Tegner knee scores at a mean of 36 months post-operatively. 40 patients were included, 21 were male and the mean age was 11.8 years. 3 cases were Meyers and McKeever type I, 13 were type II and 24 were type III. 30 underwent operative management comprising of open reduction and single screw fixation, with or without a washer. 9 patients underwent subsequent metalwork removal at a mean of 10 months post-operatively. 10 underwent non-operative management, consisting of cast immobilisation and bracing. 33 patients (83%) were available for follow up. No statistically significant differences were seen in either outcome score between those treated operatively or non-operatively, or between different grades of injury, or if metalwork were removed or not. Our study shows good functional outcomes following paediatric tibial spine fracture. We advocate the use of CT to assess fracture displacement to help guide management. We have shown type I and reducible type II injuries can successfully be managed conservatively and non-reducible type II and type III injuries can be successfully treated with open reduction and single screw fixation. In our experience post-operative knee stiffness can persist for up to 6 months but generally improves. Metalwork removal was only indicated if the patient had on going stiffness after this time or if they had on going pain.

A review of the management of blunt splenic trauma in England and Wales: have regional trauma networks influenced management strategies and outcomes?

INTRODUCTION The spleen remains one of the most frequently injured organs following blunt abdominal trauma. In 2012, regional trauma networks were launched across England and Wales with the aim of improving outcomes following trauma. This retrospective cohort study investigated the management and outcomes of blunt splenic injuries before and after the establishment of regional trauma networks. METHODS A dataset was drawn from the Trauma Audit Research Network database of all splenic injuries admitted to English and Welsh hospitals from 1 April 2010 to 31 March 2014. Demographic data, injury severity, treatment modalities and outcomes were collected. Management and outcomes were compared before and after the launch of regional trauma networks. RESULTS There were 1457 blunt splenic injuries: 575 between 2010 and 2012 and 882 in 2012-14. Following the introduction of the regional trauma networks, use of splenic artery embolotherapy increased from 3.5% to 7.6% (P = 0.001) and splenectomy rates decreased from 20% to 14.85% (P = 0.012). Significantly more patients with polytrauma and blunt splenic injury were treated with splenic embolotherapy following 2012 (61.2% vs. 30%, P < 0.0001). Increasing age, injury severity score, polytrauma and Charlson Comorbidity Index above 10 were predictors of increased mortality (P < 0.001). Increasing systolic blood pressure (odds ratio, OR, 0.757, 95% confidence interval, CI, 0.716-0.8) and Glasgow Coma Scale (OR 0.988, 95% CI 0.982-0.995) were protective. CONCLUSIONS This study demonstrates a reduction in splenectomy rate and an increased use of splenic artery embolotherapy since the introduction of the regional trauma networks. This may have resulted from improved access to specialist services and reduced practice variation since the establishment of these networks.