Publications by authors named "McKenzie I"

This paper describes muon spin spectroscopy studies of 12-phosphatetraphene stabilized by a peri-trifluoromethyl group and a meso-aryl substituent. Even though the prepared solution in tetrahydrofuran (THF) was quite dilute (0.060 M) for transverse-field muon spin rotation (TF-µSR) measurements, the π-extended heavier congener of tetraphene presented a pair of signals due to a muoniated radical from which the muon hyperfine coupling constant (hfc) was determined.

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Unlabelled: Virtual reality for routine immunisations in needle phobic children with and without developmental disabilities: a pilot study.

Background: Virtual Reality (VR) headsets can improve needle procedure success and experiences for children, but they have not been evaluated to support immunisation in children with anxiety and behavioural challenges. This study assessed the feasibility and acceptability of VR for immunisation in children with needle phobia, including children with and without developmental disabilities.

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Background: Four-factor prothrombin complex concentrate (PCC) is a plasma product that contains factors II, VII, IX, X, protein C, and protein S. PCC can be used off-label to treat coagulopathy during orthotopic liver transplantation (OLT). However, its use comes with safety concerns regarding thrombosis.

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Muonium (Mu=μe) is composed of a muon of light isotope of proton (μ) and electron (e) and can be used as a light surrogate for a hydrogen atom. In this paper, we investigated addition of muonium to a newly synthesized Mes*-substituted thioformamide (Mes*NHCH=S, Mes*=2,4,6-tBuCH). Transverse-field muon spin rotation (TF-μSR) of a solution sample of the thioformamide confirmed addition of muonium to the sulfur atom leading to the corresponding C-centered radical [Mes*NHC(H)⋅-SMu].

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The 6-(difluoromethyl)phenanthridine unit is a highly attractive fluoroalkyl-substituted planar nitrogen heterocycle in pharmaceutical and agrochemical research. In this paper, we report that difluoromethylborates can be used as a source of difluoromethyl radicals for isonitrile insertion, leading to 6-(difluoromethyl)phenanthridines. Tuning the aryl substituents in the difluoromethylborates and oxidizing reagents enabled the synthesis of 6-(difluoromethyl)phenanthridines through the generation of difluoromethyl radical and spontaneous intramolecular cyclization of the CFH-imidoyl radical intermediates.

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A man in his 70s presented to hospital in early summer with a 5-week history of progressive lower back and right thigh pain, sensory deficit and right leg weakness. There had been limited response to analgesics in the community. Primary investigations on admission revealed no cause for his symptoms.

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Cannabinoids are naturally occurring bioactive compounds with the potential to help treat chronic illnesses including epilepsy, Parkinson's disease, dementia and multiple sclerosis. Their general structures and efficient syntheses are well documented in the literature, yet their quantitative structure-activity relationships (QSARs), particularly 3-dimensional (3-D) conformation-specific bioactivities, are not fully resolved. Cannabigerol (CBG), an antibacterial precursor molecule for the most abundant phytocannabinoids, was characterised herein using density functional theory (DFT), together with selected analogues, to ascertain the influence of the 3D structure on their activity and stability.

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Entangled spin states are created by implanting muons into single-crystal LiY_{0.95}Ho_{0.05}F_{4} to form a cluster of correlated, dipole-coupled local magnetic moments.

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Article Synopsis
  • Longitudinal field muon spin relaxation (LF-μSR) experiments suggested that electron hopping rates in the organic semiconductor tris-(8-hydroxyquinoline)aluminum(III) (Alq) were around 10 seconds, but density functional theory (DFT) calculations indicated that this hopping was energetically unfavorable.
  • The study conducted avoided level crossing muon spin resonance (ALC-μSR) and transverse field muon spin rotation (TF-μSR) measurements on Alq and 8-hydroxyquinoline (8hq) to investigate the behavior of muoniated radicals, finding that the muon is integrated into molecules with localized spin density.
  • These findings suggest that muoniated radicals in Alq
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The complexation of Mg with adenosine 5'-triphosphate (ATP) is omnipresent in biochemical energy conversion, but is difficult to interrogate directly. Here we use the spin- β-emitter Mg to study Mg -ATP complexation in 1-ethyl-3-methylimidazolium acetate (EMIM-Ac) solutions using β-radiation-detected nuclear magnetic resonance (β-NMR). We demonstrate that (nuclear) spin-polarized Mg, following ion-implantation from an accelerator beamline into EMIM-Ac, binds to ATP within its radioactive lifetime before depolarizing.

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We investigated the depth, temperature, and molecular-weight (MW) dependence of the γ-relaxation in polystyrene glasses using implanted Li and β-detected nuclear magnetic resonance. Measurements were performed on thin films with MW ranging from 1.1 to 641 kg/mol.

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Avoided level crossing muon spin resonance (ALC-μSR) has been used to study the reorientational dynamics of muon-spin-labelled 2,4,6-trimethylbenzoate (246TMB) counterions and their interaction with DODMAC (dioctadecyldimethylammonium chloride) bilayers in the L and L liquid crystalline states. The muoniated radical anion formed by the addition of muonium to the secondary carbons of the aromatic ring of 246TMB is used as a local spin probe. The muon and methylene proton hyperfine parameters and the electron spin relaxation rate () of the muoniated spin probe were determined as a function of temperature by modelling the ALC-μSR spectra with Monte Carlo numerical simulations.

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In this communication, we report muon spin rotation/resonance (μSR) studies for understanding radical reactivity of 10-mesityl-1,8-bis(trifluoromethyl)-9-phosphaanthracene. Transverse-field muon spin rotation (TF-μSR) and muon avoided level-crossing resonance (μLCR) measurements successfully visualized a paramagnetic species produced by regioselective addition of muonium (Mu) to the skeletal phosphorus atom. Density functional theory (DFT) calculations for the P-muoniation product suggested two possible isomers.

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Children undergoing hematopoietic stem cell transplantation (HSCT) are vulnerable to pain due to the intensity and toxicity of this treatment. An instrumental case study design of two qualitative phases was conducted to examine the pain experiences of hospitalized children during HSCT therapy and how contextual factors related to the pediatric HSCT environment influenced their experience of pain. The Social Communication Model of Pain provided the conceptual framework for the study.

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Children's fear of a procedure, including the anesthetic, is a common issue that operating theatre staff face. This fear is generally mitigated by preesthetic preparation and information sharing. Last-minute refusal of a procedure creates unique difficulties for the anesthetist and proceduralist.

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Muon spin spectroscopic measurements were made on atactic low-molecular-weight (LMW) (1.3 kg mol) and high-molecular-weight (HMW) (202 kg mol) polystyrene. Muoniated cyclohexadienyl radicals, which are formed by muonium addition to the phenyl side groups, are used as local probes of bulk dynamics.

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Background And Aim: For infants and small toddlers with congenital upper limb deficiencies, terminal devices mainly provide either cosmesis or functionality. We report a clinical note about fitting a child with a low-cost passive hand targeting both functionality and cosmesis.

Technique: An elastomeric, alloy-wire-reinforced hand was fabricated using additive manufacturing to allow independent positioning of the digits.

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Coordinated systems of care are required to improve access to reperfusion therapies in paediatric stroke. A conceptual model was developed to map the process-of-care from symptom onset to confirmation of diagnosis. Value-Focused Process Engineering with event-driven process modelling was used to identify barriers and enablers to timely and accurate paediatric stroke diagnosis.

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We report measurements of the diffusion rate of isolated ion-implanted ^{8}Li^{+} within ∼120  nm of the surface of oriented single-crystal rutile TiO_{2} using a radiotracer technique. The α particles from the ^{8}Li decay provide a sensitive monitor of the distance from the surface and how the depth profile of ^{8}Li evolves with time. The main findings are that the implanted Li^{+} diffuses and traps at the (001) surface.

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Photonic ring resonators can be considered building blocks of new concept satellite payloads for implementing several functions, such as filtering and sensing. In particular, the use of a high Q-factor ring resonator as sensing element into a Resonant Micro Optic Gyroscope (RMOG), provides a remarkable improvement of the performance with respect to the competitive technologies. To qualify a ring resonator for Space applications, the radiation effects on it in the Space must be carefully evaluated.

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Article Synopsis
  • The study investigates how muonium (Mu) interacts with four nucleobases (adenine, guanine, cytosine, and thymine) using avoided level-crossing muon spin resonance (ALC-μSR) to characterize the resulting radicals.
  • The muoniated radicals are analyzed by comparing their hyperfine coupling constants with previous data from electron paramagnetic resonance and theoretical models, revealing that Mu primarily attaches at specific secondary carbons in the nucleobases.
  • Findings indicate Mu addition occurs predominantly at certain positions in adenine (C8 and C2), guanine (C8), cytosine (C5 and C6), and thymine (C6 and C5), each with distinctive relative yields.
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Muonium (Mu), an H atom analogue, is employed to probe the addition of free radicals to the P=C bond of a phosphaalkene. Specifically, two unprecedented muoniated free radicals, MesP -CMu(Me) (1 a, minor product) and MesPMu-C Me (1 b, major product), were detected by muon spin spectroscopy (μSR) when a solution of MesP=CMe (1: Mes=2,4,6-trimethylphenyl) was exposed to a beam of positive muons (μ ). The μ serves as a source of Mu (that is, Mu=μ +e ).

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NMR spectra of Mg2+ ions in ionic liquids were recorded using a highly sensitive variant of NMR spectroscopy known as β-NMR. The β-NMR spectra of MgCl2 in EMIM-Ac and EMIM-DCA compare favourably with conventional NMR, and exhibit linewidths of ∼3 ppm, allowing for discrimination of species with oxygen and nitrogen coordination.

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There is indirect evidence that the dynamics of a polymer near a free surface are enhanced compared with the bulk but there are few studies of how dynamics varies with depth. β-Detected nuclear spin relaxation of implanted 8Li+ has been used to directly probe the temperature and depth dependence of the γ-relaxation mode, which is due to phenyl rings undergoing restricted rotation, in thin films of atactic deuterated polystyrene (PS-d8) and determine how the depth dependence of dynamics is affected by sample processing, such as annealing, floating on water and the inclusion of a surfactant, and by the presence of a buried interface. The activation energy for the γ-relaxation process is lower near the free surface.

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