National Physics Laboratory

Teddington, United Kingdom

National Physics Laboratory

Teddington, United Kingdom
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Hinz A.,University of Oxford | Labbow R.,University of Rostock | Rennick C.,National Physics Laboratory | Schulz A.,University of Rostock | Goicoechea J.M.,University of Oxford
Angewandte Chemie - International Edition | Year: 2017

We describe the isolation and spectroscopic characterization of the heavier phosphorus-containing analogue of isocyanic acid (HPCO), and its isotopologue (DPCO). This fundamental small molecule, which has been postulated to exist in interstellar space, has thus far only been observed at low gas phase concentrations or in inert gas matrices. In this report we describe its synthesis, spectroscopic properties, and reactivity in solution. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Roberts O.J.,University of Brighton | Bruce A.M.,University of Brighton | Regan P.H.,University of Surrey | Regan P.H.,National Physics Laboratory | And 5 more authors.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2014

The design of a fast-timing γ-ray detection array aimed at measuring sub-nanosecond half-lives using LaBr3:Ce scintillation crystals is presented. This array will complement novel and existing charged particle and neutron detector arrays at the low-energy branch of a fragment separator (Super-FRS) to be built within the NuSTAR collaboration as part of the future Facility for Anti-proton and Ion Research (FAIR). The array will be used in conjunction with the Advanced Implantation Detector Array (AIDA), to measure implant-decay correlations. Monte-Carlo simulations have been performed to determine the design of the proposed fast-timing array around a localised implantation point. In particular, simulations were used to determine the full-energy peak efficiencies for single cylindrical, conical and 'hybrid' detector geometries, as well as complete array configurations of 'hybrid' and â̂...1.5 in.×2 in. cylindrical crystals. Timing precision calculations were then used to determine the timing response for each configuration based on its simulated efficiency. An informed decision based on the simulated efficiencies and timing precision calculations allowed the optimum configuration for the array to be determined. © 2014 Elsevier B.V.

Sochalski-Kolbus L.M.,Oak Ridge National Laboratory | Payzant E.A.,Oak Ridge National Laboratory | Cornwell P.A.,Oak Ridge National Laboratory | Watkins T.R.,Oak Ridge National Laboratory | And 7 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2015

Residual stress profiles were mapped using neutron diffraction in two simple prism builds of Inconel 718: one fabricated with electron beam melting (EBM) and the other with direct laser metal sintering. Spatially indexed stress-free cubes were obtained by electrical discharge machining (EDM) equivalent prisms of similar shape. The (311) interplanar spacings from the EDM sectioned sample were compared to the interplanar spacings calculated to fulfill stress and moment balance. We have shown that applying stress and moment balance is a necessary supplement to the measurements for the stress-free cubes with respect to accurate stress calculations in additively manufactured components. In addition, our work has shown that residual stresses in electron beam melted parts are much smaller than that of direct laser metal sintered parts most likely due to the powder preheating step in the EBM process. © 2015, The Minerals, Metals & Materials Society and ASM International (outside the USA).

Jha P.K.,Jaypee Institute of Information Technology | Jha P.A.,Jaypee Institute of Information Technology | Jha P.A.,Delhi Technological University | Srivastava G.,Jaypee Institute of Information Technology | And 3 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2014

In this study, authors have synthesized bismuth ferrite using (i) solid state route and (ii) mechano-chemical activation technique. The structural studies reveal the formation of bismuth ferrite of A3-δ B5O12 type by mechanochemical activation technique and of ABO3 type by conventional solid state route. In addition to the detailed studies on magnetic and electrical properties of both the samples, a comparative analysis has been done using Landau and Berry phase theory. Through this, an effort has been made to establish a relationship between magnetism and electrical polarization vis a vis magneto-electric coupling in these samples. © 2013 Elsevier B.V.

Ghita M.,Queen's University of Belfast | Coffey C.B.,University of Nevada, Reno | Butterworth K.T.,Queen's University of Belfast | McMahon S.J.,Queen's University of Belfast | And 3 more authors.
Physics in Medicine and Biology | Year: 2015

To limit toxicity to normal tissues adjacent to the target tumour volume, radiotherapy is delivered using fractionated regimes whereby the total prescribed dose is given as a series of sequential smaller doses separated by specific time intervals. The impact of fractionation on out-of-field survival and DNA damage responses was determined in AGO-1522 primary human fibroblasts and MCF-7 breast tumour cells using uniform and modulated exposures delivered using a 225 kVp x-ray source. Responses to fractionated schedules (two equal fractions delivered with time intervals from 4 h to 48 h) were compared to those following acute exposures. Cell survival and DNA damage repair measurements indicate that cellular responses to fractionated non-uniform exposures differ from those seen in uniform exposures for the investigated cell lines. Specifically, there is a consistent lack of repair observed in the out-of-field populations during intervals between fractions, confirming the importance of cell signalling to out-of-field responses in a fractionated radiation schedule, and this needs to be confirmed for a wider range of cell lines and conditions. © 2016 Institute of Physics and Engineering in Medicine.

Kaminski Schierle G.S.,University of Cambridge | Van De Linde S.,University of Würzburg | Erdelyi M.,University of Cambridge | Erdelyi M.,National Physics Laboratory | And 8 more authors.
Journal of the American Chemical Society | Year: 2011

Misfolding and aggregation of peptides and proteins is a characteristic of many neurodegenerative disorders, including Alzheimer's disease (AD). In AD the β-amyloid peptide (Aβ) aggregates to form characteristic fibrillar structures, which are the deposits found as plaques in the brains of patients. We have used direct stochastic optical reconstruction microscopy, dSTORM, to probe the process of in situ Aβ aggregation and the morphology of the ensuing aggregates with a resolution better than 20 nm. We are able to distinguish different types of structures, including oligomeric assemblies and mature fibrils, and observe a number of morphological differences between the species formed in vitro and in vivo, which may be significant in the context of disease. Our data support the recent view that intracellular Aβ could be associated with Aβ pathogenicity in AD, although the major deposits are extracellular, and suggest that this approach will be widely applicable to studies of the molecular mechanisms of protein deposition diseases. © 2011 American Chemical Society.

Seraffon M.,Cranfield University | Simms N.J.,Cranfield University | Nicholls J.R.,Cranfield University | Sumner J.,Cranfield University | Nunn J.,National Physics Laboratory
Materials at High Temperatures | Year: 2011

The effect of aerofoil geometry on the oxidative degradation mechanisms experienced by thermal barrier coatings (TBCs) used on industrial turbine blades has been investigated. Modified aerofoilshaped samples (CMSX4 coated with high-velocity oxy-fuel sprayed AMDRY 995 and air plasma sprayed TBC) were oxidised at five temperatures in furnaces from 900 to 1000°C. Scanning electron microscopy and energy dispersive X-ray analysis were used to characterise details of the microstructural evolution of the thermally grown oxide and to monitor inter-diffusion between the bond coating and substrate. Additionally, a novel non-destructive examination technique (flash thermography) was used to detect and track the spread of cracks beneath the TBCs. Multiple samples cracking in identical locations suggested an effect of geometry in the failure of coatings. Furthermore, it was observed that coating curvature influenced spinel formation.

Kim J.,University of Southampton | Wu D.S.,University of Southampton | Marra G.,National Physics Laboratory | Richardson D.J.,University of Southampton | Slavik R.,University of Southampton
Optics InfoBase Conference Papers | Year: 2014

We propose an optical injection phase locked loop (OIPLL) as a high-gain amplifier for precise frequency transfer via optical fibers. The suitability of this approach for international optical clock comparison is evaluated. © 2014 OSA.

Syed S.N.,University of Edinburgh | Schulze H.,University of Edinburgh | MacDonald D.,University of Edinburgh | Crain J.,University of Edinburgh | And 3 more authors.
Journal of the American Chemical Society | Year: 2013

Hybridization of complementary nucleic acid strands is fundamental to nearly all molecular bioanalytical methods ranging from polymerase chain reaction and DNA biosensors to next generation sequencing. For nucleic acid amplification methods, controlled DNA denaturation and renaturation is particularly essential and achieved by cycling elevated temperatures. Although this is by far the most used technique, the management of rapid temperature changes requires bulky instrumentation and intense power supply. These factors so far precluded the development of true point-of-care tests for molecular diagnostics. To overcome this limitation we explored the possibility of using electrochemical means to control reversible DNA hybridization by using the electroactive intercalator daunomycin (DM). We show that redox-state switching of DM altered its properties from DNA binding to nonbinding, under otherwise constant conditions, and thus altered the thermodynamic stability of duplex DNA. The operational principle was demonstrated using complementary synthetic 20mer and 40mer DNA oligonucleotides. Absorbance-based melting curve analysis revealed significantly higher melting temperatures for DNA in the presence of oxidized compared to chemically reduced DM. This difference was exploited to drive cyclic electrochemically controlled denaturation and renaturation. Analysis with in situ UV-vis and circular dichroism spectroelectrochemistry, as two independent techniques, indicated that up to 80% of the DNA was reversibly hybridized. This remarkable demonstration of electrochemical control of five cycles of DNA denaturation and renaturation, under otherwise constant conditions, could have wide-ranging implications for the future development of miniaturized analytical systems for molecular diagnostics and beyond. © 2013 American Chemical Society.

Ahn M.,University of Cambridge | de Genst E.,University of Cambridge | Kaminski Schierle G.S.,University of Cambridge | Erdelyi M.,University of Cambridge | And 4 more authors.
PLoS ONE | Year: 2012

Fibril formation by mutational variants of human lysozyme is associated with a fatal form of hereditary non-neuropathic systemic amyloidosis. Defining the mechanistic details of lysozyme aggregation is of crucial importance for understanding the origin and progression of this disease and related misfolding conditions. In this study, we show that a biotin moiety can be introduced site-specifically at Lys33 of human lysozyme. We demonstrate, using biophysical techniques, that the structure and stability of the native-state of the protein are not detectably altered by this modification, and that the ability to form amyloid fibrils is unchanged. By taking advantage of biotin-avidin interactions, we show that super-resolution fluorescence microscopy can generate detailed images of the mature fibrils. This methodology can readily enable the introduction of additional probes into the protein, thereby providing the means through which to understand, in detail, the nature of the aggregation process of lysozyme and its variants under a variety of conditions. © 2012 Ahn et al.

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