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Instruments / Technical Area	Publication Details	Published
	Multichannel optrodes for photonic stimulation Yingyue Xu , Nan Xia , Michelle Lim , Xiaodong Tan , Minh Ha Tran , Erin Boulger , Fei Peng , Hunter Young , Christoph Rau , Alexander Rack , Claus-peter Richter Neurophotonics 5 DOI: 10.1117/1.NPh.5.4.045002 Open Access Show Abstract ▼ Abstract: An emerging method in the field of neural stimulation is the use of photons to activate neurons. The possible advantage of optical stimulation over electrical is attributable to its spatially selective activation of small neuron populations, which is promising in generating superior spatial resolution in neural interfaces. Two principal methods are explored for cochlear prostheses: direct stimulation of nerves with infrared light and optogenetics. This paper discusses basic requirements for developing a light delivery system (LDS) for the cochlea and provides examples for building such devices. The proposed device relies on small optical sources, which are assembled in an array to be inserted into the cochlea. The mechanical properties, the biocompatibility, and the efficacy of optrodes have been tested in animal models. The force required to insert optrodes into a model of the human scala tympani was comparable to insertion forces obtained for contemporary cochlear implant electrodes. Side-emitting diodes are powerful enough to evoke auditory responses in guinea pigs. Chronic implantation of the LDS did not elevate auditory brainstem responses over 26 weeks.	Oct 2018
Detectors	Advances in indirect detector systems for ultra high-speed hard X-ray imaging with synchrotron light M. P. Olbinado , J. Grenzer , P. Pradel , T. De Resseguier , P. Vagovic , M.-c. Zdora , V. A. Guzenko , C. David , A. Rack Journal Of Instrumentation 13, C04004 - C04004 24th International congress on x-ray optics and microanalysis (ICXOM24) DOI: 10.1088/1748-0221/13/04/C04004 Show Abstract ▼ Abstract: We report on indirect X-ray detector systems for various full-field, ultra high-speed X-ray imaging methodologies, such as X-ray phase-contrast radiography, diffraction topography, grating interferometry and speckle-based imaging performed at the hard X-ray imaging beamline ID19 of the European Synchrotron—ESRF. Our work highlights the versatility of indirect X-ray detectors to multiple goals such as single synchrotron pulse isolation, multiple-frame recording up to millions frames per second, high efficiency, and high spatial resolution. Besides the technical advancements, potential applications are briefly introduced and discussed.	Apr 2018
I12-JEEP: Joint Engineering, Environmental and Processing	Identifying the Cause of Rupture of Li-Ion Batteries during Thermal Runaway Donal P. Finegan , Eric Darcy , Matthew Keyser , Bernhard Tjaden , Thomas M. M. Heenan , Rhodri Jervis , Josh J. Bailey , Nghia T. Vo , Oxana V. Magdysyuk , Michael Drakopoulos , Marco Di Michiel , Alexander Rack , Gareth Hinds , Dan J. L. Brett , Paul Shearing Advanced Science 5 DOI: 10.1002/advs.201700369 Diamond Proposal Number(s): [13884] Open Access Show Abstract ▼ Abstract: As the energy density of lithium-ion cells and batteries increases, controlling the outcomes of thermal runaway becomes more challenging. If the high rate of gas generation during thermal runaway is not adequately vented, commercial cell designs can rupture and explode, presenting serious safety concerns. Here, ultra-high-speed synchrotron X-ray imaging is used at >20 000 frames per second to characterize the venting processes of six different 18650 cell designs undergoing thermal runaway. For the first time, the mechanisms that lead to the most catastrophic type of cell failure, rupture, and explosion are identified and elucidated in detail. The practical application of the technique is highlighted by evaluating a novel 18650 cell design with a second vent at the base, which is shown to avoid the critical stages that lead to rupture. The insights yielded in this study shed new light on battery failure and are expected to guide the development of safer commercial cell designs.	Oct 2017
I12-JEEP: Joint Engineering, Environmental and Processing	Characterising thermal runaway within lithium-ion cells by inducing and monitoring internal short circuits Donal P. Finegan , Eric Darcy , Matthew Keyser , Bernhard Tjaden , Thomas M. M. Heenan , Rhodri Jervis , Josh J. Bailey , Romeo Malik , Nghia T. Vo , Oxana V. Magdysyuk , Robert Atwood , Michael Drakopoulos , Marco Dimichiel , Alexander Rack , Gareth Hinds , Dan J. L. Brett , Paul R. Shearing Energy Environ. Sci. 5 DOI: 10.1039/C7EE00385D Diamond Proposal Number(s): [13884] Show Abstract ▼ Abstract: Lithium-ion batteries are being used in increasingly demanding applications where safety and reliability are of utmost importance. Thermal runaway presents the greatest safety hazard, and needs to be fully understood in order to progress towards safer cell and battery designs. Here, we demonstrate the application of an internal short circuiting device for controlled, on-demand, initiation of thermal runaway. Through its use, the location and timing of thermal runaway initiation is pre-determined, allowing analysis of the nucleation and propagation of failure within 18[thin space (1/6-em)]650 cells through the use of high-speed X-ray imaging at 2000 frames per second. The cause of unfavourable occurrences such as sidewall rupture, cell bursting, and cell-to-cell propagation within modules is elucidated, and steps towards improved safety of 18[thin space (1/6-em)]650 cells and batteries are discussed.	Mar 2017
	Mass Density Measurement of Mineralized Tissue with Grating-Based X-Ray Phase Tomography Regine Gradl , Irene Zanette , Maite Ruiz-yaniz , Martin Dierolf , Alexander Rack , Paul Zaslansky , Franz Pfeiffer Plos One 11 DOI: 10.1371/journal.pone.0167797 Open Access Show Abstract ▼ Abstract: Establishing the mineral content distribution in highly mineralized tissues, such as bones and teeth, is fundamental in understanding a variety of structural questions ranging from studies of the mechanical properties to improved pathological investigations. However, non-destructive, volumetric and quantitative density measurements of mineralized samples, some of which may extend several mm in size, remain challenging. Here, we demonstrate the potential of grating-based x-ray phase tomography to gain insight into the three-dimensional mass density distribution of tooth tissues in a non-destructive way and with a sensitivity of 85 mg/cm3. Density gradients of 13 − 19% over 1 − 2 mm within typical samples are detected, and local variations in density of 0.4 g/cm3 on a length scale of 0.1 mm are revealed. This method proves to be an excellent quantitative tool for investigations of subtle differences in mineral content of mineralized tissues that can change following treatment or during ageing and healing.	Dec 2016
I13-2-Diamond Manchester Imaging	Hierarchical imaging of the human knee Bert Müller , Georg Schulz , Christian Götz , Hans Deyhle , Magdalena Müller-gerbl , Irene Zanette , Marie-christine Zdora , Anna Khimchenko , Peter Thalmann , Alexander Rack Developments in X-Ray Tomography X DOI: 10.1117/12.2238089 Diamond Proposal Number(s): [13210] Show Abstract ▼ Abstract: Among the clinically relevant imaging techniques, computed tomography (CT) reaches the best spatial resolution. Sub-millimeter voxel sizes are regularly obtained. For investigations on true micrometer level lab-based μCT has become gold standard. The aim of the present study is the hierarchical investigation of a human knee post mortem using hard X-ray μCT. After the visualization of the entire knee using a clinical CT with a spatial resolution on the sub-millimeter range, a hierarchical imaging study was performed using a laboratory μCT system nanotom m. Due to the size of the whole knee the pixel length could not be reduced below 65 μm. These first two data sets were directly compared after a rigid registration using a cross-correlation algorithm. The μCT data set allowed an investigation of the trabecular structures of the bones. The further reduction of the pixel length down to 25 μm could be achieved by removing the skin and soft tissues and measuring the tibia and the femur separately. True micrometer resolution could be achieved after extracting cylinders of several millimeters diameters from the two bones. The high resolution scans revealed the mineralized cartilage zone including the tide mark line as well as individual calcified chondrocytes. The visualization of soft tissues including cartilage, was arranged by X-ray grating interferometry (XGI) at ESRF and Diamond Light Source. Whereas the high-energy measurements at ESRF allowed the simultaneous visualization of soft and hard tissues, the low-energy results from Diamond Light Source made individual chondrocytes within the cartilage visual.	Aug 2016
I13-2-Diamond Manchester Imaging	Computational cell quantification in the human brain tissues based on hard x-ray phase-contrast tomograms Simone E. Hieber , Christos Bikis , Anna Khimchenko , Georg Schulz , Hans Deyhle , Peter Thalmann , Natalia Chicherova , Alexander Rack , Marie-christine Zdora , Irene Zanette , Gabriel Schweighauser , Jürgen Hench , Bert Müller Developments in X-Ray Tomography X DOI: 10.1117/12.2237012 Diamond Proposal Number(s): [13164] Show Abstract ▼ Abstract: Cell visualization and counting plays a crucial role in biological and medical research including the study of neurodegenerative diseases. The neuronal cell loss is typically determined to measure the extent of the disease. Its characterization is challenging because the cell density and size already differs by more than three orders of magnitude in a healthy cerebellum. Cell visualization is commonly performed by histology and fluorescence microscopy. These techniques are limited to resolve complex microstructures in the third dimension. Phase- contrast tomography has been proven to provide sufficient contrast in the three-dimensional imaging of soft tissue down to the cell level and, therefore, offers the basis for the three-dimensional segmentation. Within this context, a human cerebellum sample was embedded in paraffin and measured in local phase-contrast mode at the beamline ID19 (ESRF, Grenoble, France) and the Diamond Manchester Imaging Branchline I13-2 (Diamond Light Source, Didcot, UK). After the application of Frangi-based filtering the data showed sufficient contrast to automatically identify the Purkinje cells and to quantify their density to 177 cells per mm3 within the volume of interest. Moreover, brain layers were segmented in a region of interest based on edge detection. Subsequently performed histological analysis validated the presence of the cells, which required a mapping from the two- dimensional histological slices to the three-dimensional tomogram. The methodology can also be applied to further tissue types and shows potential for the computational tissue analysis in health and disease.	Aug 2016
I12-JEEP: Joint Engineering, Environmental and Processing	Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources Michael E. Rutherford , David J. Chapman , Thomas G. White , Michael Drakopoulos , Alexander Rack , Daniel E. Eakins Journal Of Synchrotron Radiation 23 (3) DOI: 10.1107/S1600577516002770 Open Access Show Abstract ▼ Abstract: The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits).	May 2016
	Multi-contrast 3D X-ray imaging of porous and composite materials Adrian Sarapata , Maite Ruiz- Yaniz , Irene Zanette , Alexander Rack , Franz Pfeiffer , Julia Herzen Applied Physics Letters 106 DOI: 10.1063/1.4918617 Show Abstract ▼ Abstract: Grating-based X-ray computed tomography allows for simultaneous and nondestructive determination of the full X-ray complex index of refraction and the scattering coefficient distribution inside an object in three dimensions. Its multi-contrast capabilities combined with a high resolution of a few micrometers make it a suitable tool for assessing multiple phases inside porous and composite materials such as concrete. Here, we present quantitative results of a proof-of-principle experiment performed on a concrete sample. Thanks to the complementarity of the contrast channels, more concrete phases could be distinguished than in conventional attenuation-based imaging. The phase-contrast reconstruction shows high contrast between the hardened cement paste and the aggregates and thus allows easy 3D segmentation. Thanks to the dark-field image, micro-cracks inside the coarse aggregates are visible. We believe that these results are extremely interesting in the field of porous and composite materials studies because of unique information provided by grating interferometry in a non-destructive way.	Apr 2015
B16-Test Beamline	Mapping the dislocation sub-structure of deformed polycrystalline Ni by scanning microbeam diffraction topography Brian Abbey , Felix Hofmann , Jonathan Belnoue , Alexander Rack , Remi Tucoulouc , Gareth Hughes , Sophie Eve , Alexander Korsunsky Scripta Materialia DOI: 10.1016/j.scriptamat.2011.01.024 Show Abstract ▼ Abstract: When subjected to plastic deformation, grains within ductile face-centred cubic polycrystals fragment into soft, low dislocation density cells separated by hard, dislocation-rich walls. Using a narrow-bandwidth, sub-micrometre X-ray beam, we have mapped the deformation structure inside a single grain within a deformed Ni polycrystal. Dislocation multiplication and entanglement was found to vary depending on the physical dimensions of the grain. The method we use overcomes current limitations in classical X-ray topography allowing topographic images to be formed from small, highly deformed grains.	Jan 2011

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