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X ray phase contrast

George S K Fung, Luisa Ciuffo, Hiroshi Ashikaga, Katsuyuki Taguchi
PURPOSE: This work concerns computed tomography (CT)-based cardiac functional analysis (CFA) with a reduced radiation dose. As CT-CFA requires images over the entire heartbeat, the scans are often performed at 10-20% of the tube current settings that are typically used for coronary CT angiography. A large image noise then degrades the accuracy of motion estimation. Moreover, even if the scan was performed during the sinus rhythm, the cardiac motion observed in CT images may not be cyclic with patients with atrial fibrillation...
June 22, 2017: Medical Physics
J Stern, T Loerting
The crystallisation behaviour of very high-density amorphous ice (VHDA) and unannealed high-density amorphous ice (uHDA) has been studied in situ by volumetry and ex situ by powder x-ray diffraction in the intermediate pressure range 0.7-1.8 GPa employing different heating rates (0.5, 5 and 30 K min(-1)). This study shows that at pressures >1 GPa the crystallisation behaviour of VHDA and uHDA is basically the same for all heating rates. That is, parallel crystallisation is almost entirely suppressed with mainly ice XII forming...
June 21, 2017: Scientific Reports
Somayeh Saghamanesh, Seyed Mohammad Reza Aghamiri, Alireza Kamali-Asl, Wataru Yashiro
An important challenge in real-world biomedical applications of X-ray phase contrast imaging (XPCI) techniques is the efficient use of the photon flux generated by an incoherent and polychromatic X-ray source. This efficiency can directly influence dose and exposure time and ideally should not affect the superior contrast and sensitivity of XPCI. In this paper, we present a quantitative evaluation of the photon detection efficiency of two laboratory-based XPCI methods, grating interferometry (GI) and coded-aperture (CA)...
June 20, 2017: Physics in Medicine and Biology
V K Sharma, Douglas G Hayes, Volker S Urban, Hugh M O'Neill, M Tyagi, E Mamontov
Bicontinous microemulsions (BμE) generally consist of nanodomains formed by surfactant in a mixture of water and oil at nearly equal proportions and are potential candidates for the solubilization and purification of membrane proteins. Here we present the first time report of nanoscopic dynamics of surfactant monolayers within BμEs formed by the anionic surfactant sodium dodecyl sulfate (SDS) measured on the nanosecond to picosecond time scale using quasielastic neutron scattering (QENS). BμEs investigated herein consisted of middle phases isolated from Winsor-III microemulsion systems that were formed by mixing aqueous and oil solutions under optimal conditions...
June 20, 2017: Soft Matter
Saffron Jade Bryant, Rob Atkin, Gregory G Warr
Phospholipids are shown by solvent penetration experiments to form lamellar phases and spontaneously spawn vesicles in a wide range of deep eutectic solvents (DESs) composed of alkylammonium halide salts and glycerol or ethylene glycol, which are shown to be nanostructured by X-ray scattering. In contrast with molecular solvents, the chain melting temperature of each phospholipid, which determines the stability of the swellable bilayer phase, depends on the structure of the cation, anion and molecular H-bond donor that constitute the DES...
June 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Alice B Chang, Christopher M Bates, Byeongdu Lee, Carol M Garland, Simon C Jones, Russell K W Spencer, Mark W Matsen, Robert H Grubbs
Block polymer self-assembly typically translates molecular chain connectivity into mesoscale structure by exploiting incompatible blocks with large interaction parameters (χij). In this article, we demonstrate that the converse approach, encoding low-χ interactions in ABC bottlebrush triblock terpolymers (χAC [Formula: see text] 0), promotes organization into a unique mixed-domain lamellar morphology, which we designate LAMP Transmission electron microscopy indicates that LAMP exhibits ACBC domain connectivity, in contrast to conventional three-domain lamellae (LAM3) with ABCB periods...
June 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
Marie-Christine Zdora, Pierre Thibault, Tunhe Zhou, Frieder J Koch, Jenny Romell, Simone Sala, Arndt Last, Christoph Rau, Irene Zanette
We present a method for x-ray phase-contrast imaging and metrology applications based on the sample-induced modulation and subsequent computational demodulation of a random or periodic reference interference pattern. The proposed unified modulated pattern analysis (UMPA) technique is a versatile approach and allows tuning of signal sensitivity, spatial resolution, and scan time. We characterize the method and demonstrate its potential for high-sensitivity, quantitative phase imaging, and metrology to overcome the limitations of existing methods...
May 19, 2017: Physical Review Letters
Tarek Alammar, Ines Hamm, Viktoria Grasmik, Michael Wark, Anja-Verena Mudring
Nanosized SrSnO3 photocatalysts have been successfully synthesized by microwave synthesis in various ionic liquids (ILs) followed by a heat treatment process to optimize the materials' crystallinity. The influence of the ILs with various cations such as 1-butyl-3-methylimidazolium ([C4mim](+)), 6-bis(3-methylimidazolium-1-yl)hexane ([C6(mim)2](2+)), butylpyridinium ([C4Py](+)), and tetradecyltrihexylphosphonium ([P66614](+)) and bis(trifluoromethanesulfonyl)amide ([Tf2N](-)) as the anion on the structure, crystallization, and morphology of the products was investigated...
June 5, 2017: Inorganic Chemistry
A Ben Gouider Trabelsi, F V Kusmartsev, M B Gaifullin, D M Forrester, A Kusmartseva, M Oueslati
We report the discovery of remarkable photo-physical phenomena with characteristics unique to epitaxial graphene grown on 6H-SiC (000-1). Surprisingly, the electrical resistance of graphene increases under light illumination in contrast to conventional materials where it normally decreases. The resistance shows logarithmic temperature dependences which may be attributed to an Altshuler-Aronov effect. We show that the photoresistance depends on the frequency of the irradiating light, with three lasers (red, green, and violet) used to demonstrate the phenomenon...
June 5, 2017: Nanoscale
Qingsong Yang, Wenxiang Cong, Ge Wang
X-ray phase contrast imaging is an important mode due to its sensitivity to subtle features of soft biological tissues. Grating-based differential phase contrast (DPC) imaging is one of the most promising phase imaging techniques because it works with a normal x-ray tube of a large focal spot at a high flux rate. However, a main obstacle before this paradigm shift is the fabrication of large-area gratings of a small period and a high aspect ratio. Imaging large objects with a size-limited grating results in data truncation which is a new type of the interior problem...
August 28, 2016: Proceedings of SPIE
Wasinee Phonsri, Phimphaka Harding, Lujia Liu, Shane G Telfer, Keith S Murray, Boujemaa Moubaraki, Tamsyn M Ross, Guy N L Jameson, David J Harding
Solvent effects in a series of Fe(iii) spin crossover (SCO) complexes [Fe(qsal-I)2]OTf·sol (sol = MeOH 1, EtOH 2, n-PrOH 3, i-PrOH 4, acetone 5 and MeCN 6) are explored. SCO is abrupt in 1 (following MeOH loss) and 2, gradual for 3 (T1/2 = 199 K) and 4 (T1/2 = 251 K) and incomplete, even up to 350 K, for 5 and 6. In [Fe(qsal-I)2]OTf SCO occurs at T1/2↓ = 225 K and T1/2↑ = 234 K (ΔT = 9 K), while aged samples of 2 exhibit an exceptionally wide hysteresis of 80 K (T1/2↓ = 139 K and T1/2↑ = 219 K). In contrast, fresh samples of 2 exhibit stepped SCO with hysteresis varying from 2 to 42 K...
May 1, 2017: Chemical Science
Yun Suk Lee, Hyun Jung Kim, Woojun Park
Although microbially induced calcium carbonate precipitation (MICP) through ureolysis has been widely studied in environmental engineering fields, urea utilization might cause environmental problems as a result of ammonia and nitrate production. In this study, many non-ureolytic calcium carbonate-precipitating bacteria that induced an alkaline environment were isolated from the rhizosphere of Miscanthus sacchariflorus near an artificial stream and their ability to precipitate calcium carbonate minerals with the absence of urea was investigated...
June 2017: Journal of Microbiology / the Microbiological Society of Korea
Dima Bolmatov, Mikhail Zhernenkov, Lewis Sharpnack, Deña M Agra-Kooijman, Satyendra Kumar, Alexey Suvorov, Ronald Pindak, Yong Q Cai, Alessandro Cunsolo
The investigation of phononic collective excitations in soft matter systems at the molecular scale has always been challenging due to limitations of experimental techniques in resolving low-energy modes. Recent advances in inelastic X-ray scattering (IXS) enabled the study of such systems with unprecedented spectral contrast at meV excitation energies. In particular, it has become possible to shed light on the low-energy collective motions in materials whose morphology and phase behavior can easily be manipulated, such as mesogenic systems...
June 14, 2017: Nano Letters
Andreas Voss, Knut Beitzel, Elifho Obopilwe, Stefan Buchmann, John Apostolakos, Jessica Di Venere, Michael Nowak, Mark P Cote, Anthony A Romeo, Augustus D Mazzocca
BACKGROUND: The purpose of this study was to examine biomechanical properties and the degree of radiolucency of two cemented basic glenoid designs for total shoulder arthroplasty. Our hypothesis was that a component with increased micro-motion in the laboratory at time zero would also exhibit a greater amount of radiolucency in patients at a minimum of 2 years post total shoulder arthroplasty. METHODS: Thirty cadaveric shoulders were divided into 2 groups (keel vs...
May 25, 2017: BMC Musculoskeletal Disorders
Saad Alrwashdeh, Ingo Manke, Henning Markötter, Merle Klages, Martin Göbel, Jan Haußmann, Joachim Scholta, John Banhart
Understanding the function of nanoporous materials employed in polymer electrolyte membrane fuel cells (PEMFCs) is crucial to improve their performance, durability and cost efficiency. Up to now, the water distribution in the nm-sized pore structures was hardly accessible during operation of the cells. Here we demonstrate that phase contrast synchrotron X-ray tomography allows for an in-operando quantification of the three-dimensional water distribution within the nm-sized pores of carbon-based micro porous layers (MPLs)...
May 25, 2017: ACS Nano
Rüdiger von Kummer, Imanuel Dzialowski
PURPOSE: In acute cerebral ischemia, the assessment of irreversible injury is crucial for treatment decisions and the patient's prognosis. There is still uncertainty how imaging can safely differentiate reversible from irreversible ischemic brain tissue in the acute phase of stroke. METHODS: We have searched PubMed and Google Scholar for experimental and clinical papers describing the pathology and pathophysiology of cerebral ischemia under controlled conditions...
May 24, 2017: Neuroradiology
Monika Tomczyk, Daniel G Stroppa, Ian M Reaney, Paula M Vilarinho
BiFeO3 (BFO) thin films were grown by chemical solution deposition on a range of electrodes to determine their role in controlling the phase formation and microstructure of the films. The crystallization on oxide electrodes followed the sequence: amorphous → Bi2O2(CO3) → perovskite, while those on Pt crystallized directly from the amorphous phase. IrO2 electrodes promoted perovskite phase formation at the lowest temperature and LaNiO3 additionally induced local epitaxial growth. All compositions exhibited fully coherent Fe-rich precipitates within the grain interior of the perovskite matrix, whereas the incoherent Bi2Fe4O9 second phase was also observed at the grain boundaries of BFO grown on Pt electrodes...
June 7, 2017: Physical Chemistry Chemical Physics: PCCP
Alberto Astolfo, Marco Endrizzi, Fabio A Vittoria, Paul C Diemoz, Benjamin Price, Ian Haig, Alessandro Olivo
X-ray phase contrast imaging (XPCI) is an innovative imaging technique which extends the contrast capabilities of 'conventional' absorption based x-ray systems. However, so far all XPCI implementations have suffered from one or more of the following limitations: low x-ray energies, small field of view (FOV) and long acquisition times. Those limitations relegated XPCI to a 'research-only' technique with an uncertain future in terms of large scale, high impact applications. We recently succeeded in designing, realizing and testing an XPCI system, which achieves significant steps toward simultaneously overcoming these limitations...
May 19, 2017: Scientific Reports
Mahati Chintapalli, Ksenia Timachova, Kevin R Olson, Michał Banaszak, Jacob L Thelen, Sue J Mecham, Joseph M DeSimone, Nitash P Balsara
Incipient microphase separation is observed by wide angle X-ray scattering (WAXS) in short chain multiblock copolymers consisting of perfluoropolyether (PFPE) and poly(ethylene oxide) (PEO) segments. Two PFPE-PEO block copolymers were studied; one with dihydroxyl end groups and one with dimethyl carbonate end groups. Despite having a low degree of polymerization (N ∼ 10), these materials exhibited significant scattering intensity, due to disordered concentration fluctuations between their PFPE-rich and PEO-rich domains...
June 7, 2017: Soft Matter
Magdalena Kołodziej, Michael J de Veer, Marian Cholewa, Gary F Egan, Bruce R Thompson
Monitoring of pulmonary physiology is fundamental to the clinical management of patients with Cystic Fibrosis. The current standard clinical practise uses spirometry to assess lung function which delivers a clinically relevant functional readout of total lung function, however does not supply any visible or localised information. High Resolution Computed Tomography (HRCT) is a well-established current 'gold standard' method for monitoring lung anatomical changes in Cystic Fibrosis patients. HRCT provides excellent morphological information, however, the X-ray radiation dose can become significant if multiple scans are required to monitor chronic diseases such as cystic fibrosis...
May 17, 2017: Respiratory Research
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