Magnetic properties of Hydrogenated Li and Co doped ZnO nanoparticles

The effect of hydrogenation on magnetic properties of Zn0.85Co0.05Li0.10O nanoparticles is presented. It was found that the sample hydrided at room temperature (RT) showed weak ferromagnetism (FM) while that hydrided at 400oC showed robust ferromagnetism at room temperature. In both cases reheating the sample at 400oC in air converts it back into paramagnetic state (P) completely. The characterization of samples by X-ray and electron diffraction (ED) showed that room temperature ferromagnetism observed in the samples hydrogenated at RT is intrinsic in nature whereas that observed in the samples hydrogenated at 400oC is partly due to the cobalt metal clusters.Comment: 10 pages, 3 figure

Patient advice regarding participation in sport in children with disorders of cerebrospinal fluid (CSF) circulation: a national survey of British paediatric neurosurgeons

Background Management of children with disorders of cerebrospinal fluid (CSF) circulation is a common aspect of paediatric neurosurgical practice. Sport and physical activity play an integral role in the lives of patients in this age group. However, there is little evidence to support the dissemination of appropriate advice to children regarding such activities. The aim of this study was to evaluate the perspectives of clinicians across the UK regarding the participation of children with disorders of CSF circulation in sports. Methods Questionnaires were distributed to Consultant Paediatric Neurosurgeons practising across the UK via the Society of British Neurological Surgeons (SBNS). Five different patient scenarios were supplied, and participants were asked to choose whether they would advise participation in the following sports: Taekwondo, rugby, skiing, and football. Results An overall response rate of 66.7% (36 out of 54 paediatric neurosurgeons) was achieved. The following percentages of clinicians advocated football, rugby, Taekwondo, and skiing across all scenarios: 96%, 75%, 77%, and 97%, respectively. The majority of responders (91.2%) relied on personal experience when providing advice, whilst 50% used available literature and 19.4% used available guidelines. Conclusions There is a paucity of evidence in the literature to support the dissemination of appropriate advice to children with disorders of CSF circulation regarding participation in sports. Our findings demonstrate that the majority of clinicians rely on personal experience to make such decisions, emphasizing the necessity of larger scale studies to inform evidence-based guidelines

Thermal Stability of Zirconia-coated Multiwalled Carbon Nanotubes

Sol-gel method has been used to coat multiwalled carbon nanotubes (MWCNTs) with zirconia at room temperature and the coated tubes were sintered at high temperature. The samples were characterised by Raman spectroscopy, x-ray diffraction, environmental scanning electron microscope, transmission electron microscopy, and energy-dispersive x-ray analyses. The performance of the coated-MWCNTs was investigated as a function of temperature. The TGA studies indicated that sintering of coated-MWCNTs has improved its oxidation resistance and this improvement is related to the proper selection of sintering temperature.Defence Science Journal, 2010, 60(3), pp.337-342, DOI:http://dx.doi.org/10.14429/dsj.60.36

Ground State of the Singly Ionized Oxygen Vacancy in Rutile TiO\u3csub\u3e2\u3c/sub\u3e

Results from electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) experiments are used to establish the model for the ground state of the singly ionized oxygen vacancy in the interior of bulk rutile TiO2 crystals. Hyperfine from 47Ti and 49Ti nuclei show that the unpaired electron in this S = 1/2 defect is localized on one titanium ion adjacent to the oxygen vacancy (i.e., the spin is not shared by two titanium ions). These defects are formed at low temperature (∼35 K) in as-grown oxidized crystals when sub-band-gap 442 nm laser light converts doubly ionized nonparamagnetic oxygen vacancies to the singly ionized paramagnetic charge state. The g matrix is obtained from EPR spectra and the 47Ti and 49Ti hyperfine and nuclear electric quadrupole matrices (A and Q) are obtained from ENDOR spectra. Principal values of the 47Ti and 49Ti hyperfine matrices are 64.54, 11.57, and 33.34 MHz. All the matrices have a principal axis along the [001] direction. In the basal plane, principal axes of the hyperfine and quadrupole matrices also coincide. The principal axes of the g matrix in the basal plane, however, deviate significantly from those of the A and Q matrices, thus indicating mixing of d orbitals due to the low symmetry at the Ti3+ ion site and participation of excited-state orbitals

Improved control strategy of DFIG-based wind turbines using direct torque and direct power control techniques

This paper presents different control strategies for a variable-speed wind energy conversion system (WECS), based on a doubly fed induction generator. Direct Torque Control (DTC) with Space-Vector Modulation is used on the rotor side converter. This control method is known to reduce the fluctuations of the torque and flux at low speeds in contrast to the classical DTC, where the frequency of switching is uncontrollable. The reference for torque is obtained from the maximum power point tracking technique of the wind turbine. For the grid-side converter, a fuzzy direct power control is proposed for the control of the instantaneous active and reactive power. Simulation results of the WECS are presented to compare the performance of the proposed and classical control approaches.Peer reviewedFinal Accepted Versio

The efficacy of endoscopic third ventriculostomy in children 1 year of age or younger: A systematic review and meta-analysis

Purpose Hydrocephalus is a major cause of morbidity in the pediatric population, with potentially severe consequences if left untreated. Two viable strategies for management of non-communicating hydrocephalus are endoscopic third ventriculostomy (ETV) and ventriculoperitoneal shunting. However, there is uncertainty over the safety and efficacy of ETV in younger infants aged 1 year or below. In this systematic review, we aim to elucidate the success rate and procedural risks of ETV in this age group. Methods A multi-database (PubMed, Embase, Web of Science) literature search between January 1990 and April 2018 was performed in accordance with PRISMA guidelines. Eligible studies were included if they (i) examined non-communicating hydrocephalus; (ii) quantified the success/failure rates of ETV; and (iii) assessed outcomes in children 1 year of age or younger. Results A total of 19 articles with 399 patients were eligible for inclusion. Mean age at procedure was 4.2 months (range 34 weeks gestation to 12 months), with 116 females and 143 males. Commonest underlying aetiology was congenital aqueductal stenosis (AS) (60.4%). Remaining causes included post-haemorrhagic, post-infection, Chiari malformations, malignancies and others. Overall and AS mean success rates were 51.6% and 56.5% respectively. Overall complication rate was 10.0%, consisting mainly of CSF leak, infection, and haemorrhage. Younger age was significantly associated with poorer ETV success rate when divided into <6 months and 6–12 months of age (44.4 vs 66.7%; p = 0.0007). Underlying pathology had no significant association with ETV outcome when divided into AS and other pathologies (p = 0.53). Conclusions Age is significantly associated with ETV success rates. Pathology-dependent effects were not found in this age group. Despite a lower ETV success rate at younger ages (44.4 vs 66.7%), it offers a comparable safety profile that is independent of age. ETV remains a viable treatment option for non-communicating hydrocephalus for infants aged 1 year or younger

Triplet Ground State of the Neutral Oxygen-vacancy Donor in Rutile TiO\u3csub\u3e2\u3c/sub\u3e

Electron paramagnetic resonance (EPR) is used to investigate the triplet (S = 1) ground state of the neutral oxygen vacancy in bulk rutile TiO2 crystals. This shallow donor consists of an oxygen vacancy with two nearest-neighbor, exchange-coupled 3+ ions located along the [001] direction and equidistant from the vacancy. The spins of the two trapped electrons, one at each 3+ ion, align parallel to give the S = 1 state. These neutral oxygen vacancies are formed near 25 K in as-grown oxidized TiO2 crystals by illuminating with sub-band-gap 442 nm laser light. The angular dependence of the EPR spectra provides the principal values and axes for the g and D matrices. Observations of the Ti and Ti hyperfine lines when the magnetic field is along high-symmetry directions show that the two 3+ ions are equivalent; i.e., they have equal hyperfine A matrices. The A matrix for each 3+ ion in the neutral S = 1 oxygen vacancy is approximately half of the A matrix reported earlier for the one 3+ ion in the singly ionized S = 1/2 oxygen vacancy [Brant et al., J. Appl. Phys. 114, 113702 (2013)]. The neutral oxygen vacancies are thermally unstable above 25 K. They release an electron to the conduction band with an activation energy near 63 meV and convert to singly ionized S = 1/2 oxygen vacancies. When undoped TiO2 is sufficiently oxygen deficient (i.e., reduced), this combination of conduction band electrons and singly ionized oxygen vacancies may result in carrier-mediated ferromagnetism at room temperature

Management of neurotrauma during COVID-19: a single centre experience and lessons for the future

Introduction: Traumatic brain injury (TBI) is amongst the leading causes of morbidity and mortality worldwide. The unprecedented emergence of COVID-19 has mandated neurosurgeons to limit viral spread and spare hospital resources whilst trying to adapt management plans for TBI. We aimed to characterize how this affects decision-making on TBI management and drive strategies to cope with future expected waves. Methods: Retrospective TBI data collection from a single tertiary referral unit was performed between: 01/04/2019 – 30/06/2019 (‘Pre-Epidemic’) and 01/04/2020 – 30/06/20 (‘Epidemic’). Demographics, mechanism of injury, TBI severity, radiological findings, alcohol/anticoagulants/antiplatelets use, and management decisions were extracted. Results: 646 TBI referrals were received in ‘Pre-Epidemic’ (N = 317) and ‘Epidemic’ (N = 280) groups. There was reduction in RTA-associated TBI (14.8 vs 9.3%; p = .04) and increase in patients on anticoagulants (14.2 vs 23.6%; p = .003) in the ‘Epidemic’ group. Despite similarities between other TBI-associated variables, a significantly greater proportion of patients were managed conservatively in local referring units without neurosurgical services (39.1 vs 56.8%; p < .0001), predominantly constituted by mild TBI. Conclusion: Despite COVID-19 public health measures, the burden of TBI remains eminent. Increases in local TBI management warrant vigilance from primary healthcare services to meet post-TBI needs in the community

Stepped-wedge randomised trial of laparoscopic ventral mesh rectopexy in adults with chronic constipation: Study protocol for a randomized controlled trial

BACKGROUND: Laparoscopic ventral mesh rectopexy (LVMR) is an established treatment for external full-thickness rectal prolapse. However, its clinical efficacy in patients with internal prolapse is uncertain due to the lack of high-quality evidence. METHODS: An individual level, stepped-wedge randomised trial has been designed to allow observer-blinded data comparisons between patients awaiting LVMR with those who have undergone surgery. Adults with symptomatic internal rectal prolapse, unresponsive to prior conservative management, will be eligible to participate. They will be randomised to three arms with different delays before surgery (0, 12 and 24 weeks). Efficacy outcome data will be collected at equally stepped time points (12, 24, 36 and 48 weeks). The primary objective is to determine clinical efficacy of LVMR compared to controls with reduction in the Patient Assessment of Constipation Quality of Life (PAC-QOL) at 24 weeks serving as the primary outcome. Secondary objectives are to determine: (1) the clinical effectiveness of LVMR to 48 weeks to a maximum of 72 weeks; (2) pre-operative determinants of outcome; (3) relevant health economics for LVMR; (4) qualitative evaluation of patient and health professional experience of LVMR and (5) 30-day morbidity and mortality rates. DISCUSSION: An individual-level, stepped-wedge, randomised trial serves the purpose of providing an untreated comparison for the active treatment group, while at the same time allowing the waiting-listed participants an opportunity to obtain the intervention at a later date. In keeping with the basic ethical tenets of this design, the average waiting time for LVMR (12 weeks) will be shorter than that for routine services (24 weeks)