Publications by authors named "Hawker R"

Pyrroles are important -heterocycles found in medicines and materials. The formation of pyrroles from widely accessible pyrrolidines is a potentially attractive strategy but is an underdeveloped approach due to the sensitivity of pyrroles to the oxidative conditions required to achieve such a transformation. Herein, we report a catalytic approach that employs commercially available B(CF) in an operationally simple procedure that allows pyrrolidines to serve as direct synthons for pyrroles.

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Introduction: Patients with episodes of supraventricular tachycardia (SVT), a common heart arrhythmia, are often attended by ambulance services. International guidelines advocate treatment with the Valsalva manoeuvre (VM), but this simple physical treatment has a low success rate, with most patients requiring conveyance to hospital. The Valsalva Assist Device (VAD) is a simple device that might help practitioners and patients perform a more effective VM and reduce the need for patients to be taken to hospital.

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Rate constants for a bimolecular nucleophilic substitution (SN2) process in a range of ionic liquids are correlated with calculated parameters associated with the charge localisation on the cation of the ionic liquid (including the molecular electrostatic potential). Simple linear regression models proved effective, though the interdependency of the descriptors needs to be taken into account when considering generality. A series of ionic liquids were then prepared and evaluated as solvents for the same process; this data set was rationally chosen to incorporate homologous series (to evaluate systematic variation) and functionalities not available in the original data set.

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X-ray photoelectron spectroscopy (XPS) is a powerful element-specific technique to determine the composition and chemical state of all elements in an involatile sample. However, for elements such as carbon, the wide variety of chemical states produce complex spectra that are difficult to interpret, consequently concealing important information due to the uncertainty in signal identity. Here we report a process whereby chemical modification of carbon structures with electron withdrawing groups can reveal this information, providing accurate, highly refined fitting models far more complex than previously possible.

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Correction for 'Rationalising the effects of ionic liquids on a nucleophilic aromatic substitution reaction' by Rebecca R. Hawker et al., Org.

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A variety of ionic liquids, each containing the same cation but a different anion, were examined as solvents for a nucleophilic aromatic substitution reaction. Varying the proportion of ionic liquid was found to increase the rate constant as the mole fraction of ionic liquid increased demonstrating that the reaction outcome could be controlled through varying the ionic liquid. The solvent effects were correlated with the hydrogen bond accepting ability (β) of the ionic liquid anion allowing for qualitative prediction of the effect of changing this component of the solute.

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A range of ionic liquids was examined as solvents for a substitution reaction. They were chosen through rationally varying the ionic liquid cation in order to enhance the rate constant. Access to charge and electron-withdrawing substituents benefitted rate enhancement, allowing ionic liquids to be rationally selected to control reaction outcome.

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Purpose: Internationally there is no consensus on the indicators essential for determining safe recovery from anesthesia and patient readiness for discharge from the postanesthesia care unit (PACU).

Design: Integrative review.

Methods: Using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) as a search strategy, the literature related to PACU discharge scores were evaluated and organized into themes.

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The nucleophilic aromatic substitution reaction between 1-fluoro-2,4-dinitrobenzene and ethanol was examined in a series of ionic liquids across a range of mole fractions. Temperature-dependent kinetic analyses were undertaken to determine the activation parameters for this reaction at the highest mole fraction. As the mole fraction of ionic liquid was increased, the rate constant of the reaction also increased, however the microscopic origin of the rate enhancement was shown to be different between different ionic liquids and also between different solvent compositions.

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Novel ionic liquids containing chlorine atoms on the imidazolium cation were synthesised. The physicochemical properties of these ionic liquids were investigated extensively, including glass transition, melting and decomposition temperatures, density, viscosity, miscibility with common solvents and electrochemical window. The behaviour of these ionic liquids as solvents was examined through temperature-dependent kinetic analyses on two reactions: a nucleophilic aromatic substitution (S Ar) reaction and a bimolecular nucleophilic substitution (S 2) reaction.

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The effect of a range of ionic liquids, with systematic variations in the cation and anion, on the rate constant of an aromatic substitution process was investigated. Temperature-dependent kinetic data allowed calculation of activation parameters for the process in each solvent. These data demonstrate a generalised ionic liquid effect, with an increase in rate constant observed in each ionic solvent, though the microscopic origins of the rate constant enhancement differ with the nature of the ionic liquid.

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The rate of reaction of a Menschutkin process in a range of ionic liquids with different cations was investigated, with temperature-dependent kinetic data giving access to activation parameters for the process in each solvent. These data, along with molecular dynamics simulations, demonstrate the importance of accessibility of the charged centre on the cation and that the key interactions are of a generalised electrostatic nature.

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Background: Anomalous systemic arterial supply to normal segments of the lung is an unusual anomaly. It represents part of a spectrum of bronchovascular abnormalities which have various anatomical and clinical manifestations.

Methods: We retrospectively analysed cases from January 2007 to April 2010 from two institutions diagnosed with an anomalous systemic arterial supply to a normal lung segment.

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Background: Dopamine agonists are being used increasingly as first line treatment for Parkinson's disease, but there remains uncertainty about their clinical and cost-effectiveness relative to levodopa.

Objectives: This meta-analysis aims to quantify more reliably the benefits and risks of dopamine agonists compared to placebo or levodopa in early Parkinson's disease.

Search Strategy: We searched CENTRAL (The Cochrane Library), MEDLINE, EMBASE, PubMed, LILACS and Web of Science, plus major journals in the field, abstract books, conference proceedings and reference lists of retrieved publications.

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Background: The prevalence of thrombosis after the Fontan procedure depends upon the surgical technique used and the method of detection employed. Current investigations for thrombosis lack sensitivity and specificity or, in the paediatric population, require a general anaesthetic. We undertook a study to examine the feasibility of using magnetic resonance imaging (MRI) to detect thrombosis within the conduit, cardiac chambers and pulmonary arteries after the extracardiac conduit modification of the Fontan procedure.

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Objective: To report on the 'Operation Open Heart' (OOH) cardiac surgical program in Papua New Guinea (PNG). To document the short-term surgical outcome, the experience gained and the skill transfer from the visiting team members to their PNG counterparts.

Methodology: Analysis of the database compiled from the records of the patients who were operated on by the visiting cardiothoracic surgical team.

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Aim: To describe cardiac surgery, survival and outcomes for low-birthweight (< or = 2500 g) infants undergoing surgery for congenital heart disease.

Methods: Using data from a prospectively collected population-based database of admissions to neonatal intensive care units in New South Wales and the Australian Capital Territory, we identified all low-birthweight infants undergoing cardiac surgery between 1992 and 2001. Infants with only a persistent ductus arteriosus were excluded.

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Background: Although repair of Tetralogy of Fallot (TOF) and transposition of the great arteries (TGA) has facilitated survival into adulthood, many survivors have residual haemodynamic abnormalities, including exercise intolerance and late right ventricular (RV) failure.

Methods: We studied 40 asymptomatic adult subjects (31.3+/-1.

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The MRI findings of a case of coronary artery fistula occurring in a patient with pulmonary atresia and tricuspid atresia is presented.

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The objectives of this study were to examine the relative contributions of development and hemodynamics in aortic root dilatation of tetralogy of Fallot, to assess the impact of systemic to pulmonary artery shunt on aortic annular size, and to seek any relationship between the timing of corrective surgery and subsequent aortic root size. We performed a retrospective analytical study at a tertiary referral center of M-mode and two-dimensionol aortic root measurements in children with tetralogy of Fallot prior to any surgical or palliative intervention, after insertion of a surgical shunt, and on intermediate and long-term follow-up post-repair. The main outcome measures were aortic root diameter prior to correction, after palliative shunt insertion, and after definitive repair.

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This study reports the medium-to-long-term outcome in Papua New Guinean (PNG) children selected to undergo cardiac surgery at the Royal Alexandra Hospital for Children in Sydney, Australia between 1978 and 1994. Follow-up ranged from 4 to 20 (median 11) years. The cohort comprised 125 children who had surgery and 31 who were initially selected in PNG for surgery but who on further investigation were found to be unsuitable.

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Background: In 1941, a Sydney ophthalmologist, Norman McAlister Gregg, correctly identified the link between congenital cataracts in infants and maternal rubella early in pregnancy. Fifty of Gregg's subjects with congenital rubella, born in 1939-1944, were reviewed in 1967 and again in 1991. We reviewed this cohort in 2000-2001, 60 years after their intrauterine infection.

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