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X ray phase contrast

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...
May 18, 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
Michael G Siskos, M Iqbal Choudhary, Ioannis P Gerothanassis
Numerous gas phase electron diffraction, ultra-fast electron diffraction, X-ray and neutron diffraction experiments on β-dicarbonyl compounds exhibiting enol-enol tautomeric equilibrium, with emphasis on acetylacetone and dibenzoylmethane, have so far been reported with conflicting results on the structural details of the O-HO intramolecular hydrogen bond and resulted in alternative hypotheses on the intramolecular hydrogen bond potential function either a double minimum potential corresponding to two tautomeric forms in equilibrium or a single symmetrical one...
May 17, 2017: Organic & Biomolecular Chemistry
Joshua Demuth, Eli Fahrenkrug, Luyao Ma, Titilayo Shodiya, Julia I Deitz, Tyler J Grassman, Stephen Maldonado
Deposition of epitaxial germanium (Ge) thin films on silicon (Si) wafers has been achieved over large areas with aqueous feedstock solutions using electrochemical liquid phase epitaxy (ec-LPE) at low temperatures (T ≤ 90 °C). The ec-LPE method uniquely blends the simplicity and control of traditional electrodeposition with the material quality of melt growth. A new electrochemical cell design based on the compression of a liquid metal electrode into a thin cavity that enables ec-LPE is described. The epitaxial nature, low strain character, and crystallographic defect content of the resultant solid Ge films were analyzed by electron backscatter diffraction, scanning transmission electron microscopy, high resolution X-ray diffraction, and electron channeling contrast imaging...
May 9, 2017: Journal of the American Chemical Society
Sarah Frisco, Danny Liu, Arjun Kumar, Jay F Whitacre, Corey T Love, Karen Swider-Lyons, Shawn Litster
While some commercially available primary batteries have lithium metal anodes, there has yet to be a commercially viable secondary battery with this type of electrode. Research prototypes of these cells typically exhibit a limited cycle life before dendrites form and cause internal cell shorting, an occurrence that is more pronounced during high rate cycling. To better understand the effects of high rate cycling that can lead to cell failure, we use ex-situ nano-scale resolution X-ray computed tomography (nano-CT) with the aid of Zernike phase contrast to image the internal morphologies of lithium metal electrodes on copper wire current collectors that have been cycled at low and high current densities...
May 9, 2017: ACS Applied Materials & Interfaces
Rintaro Takahashi, Sakiko Matsumoto, Shota Fujii, Theyencheri Narayanan, Kazuo Sakurai
Calix[4]arene-derived surfactants form monodisperse micelles with a well-defined aggregation number (Nagg ) of 4, 6, 8, 12, or 20, corresponding to the Platonic solids. This feature is in strong contrast to conventional micelles. In this study, a transition from a dodecamer (Nagg =12) to an icosamer (Nagg =20) was induced by a rapid increase in the NaCl concentration (CNaCl ) using a stopped-flow device and directly observed by time-resolved small-angle X-ray scattering. The Nagg remained unchanged during the first 60 s after the increase in CNaCl  , and then abruptly increased to 20...
May 8, 2017: Angewandte Chemie
Venugopal Elakkiya, Mridula Prakash Menon, Devaraj Nataraj, Pullithadathil Biji, Rajendran Selvakumar
The present study focus on optical sensing of breast cancer antigen 15.3 (CA 15.3) using cadmium sulphide quantum dot (CdS-QD) in saline and serum samples spiked with antigen. The surface of CdS-QD was modified by cysteamine capping followed by tagging of CA 15.3 antibody. The samples were characterised using UV-visible absorption spectroscopy (UV-VIS Spectroscopy), Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HRTEM) attached with energy-dispersive X-ray spectroscopy, phase contrast inverted epi-fluorescence microscopy and photoluminescence (PL) spectrophotometry (EDS)...
April 2017: IET Nanobiotechnology
Priti S Mohanty, Sofi Nöjd, Kitty van Gruijthuijsen, Jérôme J Crassous, Marc Obiols-Rabasa, Ralf Schweins, Anna Stradner, Peter Schurtenberger
Soft particles such as polymeric microgels can form ultra-dense phases, where the average center-to-center distance a s can be smaller than the initial unperturbed particle diameter σ 0, due to their ability to interpenetrate and compress. However, despite of the effort devoted to microgels at ultrahigh densities, we know surprisingly little about their response to their environment at effective volume fractions ϕ eff above close packing (ϕ cp ), and the existing information is often contradictory. Here we report direct measurements of the size and shape of poly(N-isopropylacrylamide) microgels at concentrations below and above ϕ cp using the zero average contrast method in small-angle neutron scattering...
May 3, 2017: Scientific Reports
Adam Grzelak, Jakub Gawraczyński, Tomasz Jaroń, Maddury Somayazulu, Mariana Derzsi, Viktor Struzhkin, Wojciech Grochala
The X-ray diffraction data collected up to ca. 56 GPa and the Raman spectra measured up to 74.8 GPa for AgO, or Ag(I)Ag(III)O2, which is a prototypical mixed valence (disproportionated) oxide, indicate that two consecutive phase transitions occur: the first-order phase transition occurs between 16.1 GPa and 19.7 GPa, and a second-order phase transition occurs at ca. 40 GPa. All polymorphic forms host the square planar [Ag(III)O4] units typical of low-spin Ag(III). The disproportionated Imma form persists at least up to 74...
May 2, 2017: Inorganic Chemistry
Jie Xiao, Ce Shi, Li Zhang, Yunqi Li, Junru Qi, Yan Wang, Qingrong Huang
The structural responses of soy protein isolate under various processing conditions are of practically important for broadening its functionalities. In this work, multilevel structural responses of β-conglycinin and glycinin under acidic or alkaline heat treatment were investigated. Our results suggested that heat treatment under acidic (i.e., pH2.5) or alkaline (i.e., pH8.5) conditions induced multilevel structural responses of β-conglycinin and glycinin: under acidic heat treatment, both β-conglycinin and glycinin underwent hydrolysis and experienced disruption and reorganization in ordered secondary structure...
November 2016: Food Research International
Sindy Lindner, Kai Gruhle, Rico Schmidt, Vasil M Garamus, Daniel Ramsbeck, Gerd Hause, Annette Meister, Andrea Sinz, Simon Drescher
In the present work, we describe the synthesis and the temperature-dependent behavior of photoreactive membrane lipids as well as their capability to study peptide/lipid interactions. The modified phospholipids contain an azide group either in the middle part or at the end of an alkyl chain and also differ in the linkage (ester vs ether) of the second alkyl chain. The temperature-dependent aggregation behavior of the azidolipids was studied using differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and small-angle X-ray scattering (SAXS)...
May 10, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
P Deman, S Tan, G Belev, N Samadi, M Martinson, D Chapman, N L Ford
In this study, contrast-enhanced X-ray tomographic imaging for monitoring and quantifying respiratory disease in preclinical rodent models is proposed. A K-edge imaging method has been developed at the Canadian Light Source to very accurately obtain measurements of the concentration of iodinated contrast agent in the pulmonary vasculature and inhaled xenon in the airspaces of rats. To compare the iodine and xenon concentration maps, a scout projection image was acquired to define the region of interest within the thorax for imaging and to ensure the same locations were imaged in each K-edge subtraction (KES) acquisition...
May 1, 2017: Journal of Synchrotron Radiation
Daniel González-Mancebo, Ana Isabel Becerro, Eugenio Cantelar, Fernando Cussó, Arnaud Briat, Damien Boyer, Manuel Ocaña
Uniform, hydrophilic 50 nm diameter Nd(3+)-doped Ba0.3Lu0.7F2.7 nanospheres are synthesized at 120 °C using a singular one-pot method based on the use of ethylene glycol as solvent, in the absence of any additive. The composition and crystal structure of the undoped material are analyzed in detail using ICP and XRD, which reveals a BaF2 cubic crystal structure that is able to incorporate 70 mol% of Lu ions. This finding contrasts with the reported phase diagram of the system, where the maximum solubility is around 30 mol% Lu...
April 27, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Rolf Symons, Bernhard Krauss, Pooyan Sahbaee, Tyler E Cork, Manu N Lakshmanan, David A Bluemke, Amir Pourmorteza
PURPOSE: To demonstrate the feasibility of spectral imaging using photon-counting detector (PCD) x-ray computed tomography (CT) for simultaneous material decomposition of 3 contrast agents in vivo in a large animal model. METHODS: This Institutional Animal Care and Use Committee-approved study used a canine model. Bismuth subsalicylate was administered orally 24-72 hours before imaging. PCD CT was performed during intravenous administration of 40-60 ml gadoterate meglumine; 3...
April 26, 2017: Medical Physics
Stephen J Pennycook
Over the last three decades the scanning transmission electron microscope (STEM) has gone from a specialized instrument for nanoscale analysis to the microscope of choice for atomic resolution imaging of materials, allowing incoherent high-angle annular dark field (Z-contrast) imaging, coherent phase contrast modes (conventional and annular bright field), electron energy loss and energy dispersive X-ray spectroscopy. All signals are achieving atomic resolution and several are available simultaneously. This would not have been possible without the development of an aberration corrector for the STEM, spearheaded by Ondrej Krivanek in the late 1990s, which finally allowed the benefits of the STEM to translate from "in-principle" to actual daily practice...
March 18, 2017: Ultramicroscopy
Atsushi Momose
Since the 1990s, the use of X-ray phase contrast has been extensively studied for imaging weakly absorbing objects consisting of low-Z elements such as biological soft tissues and polymers. The development of X-ray microscopy was also progressing during this time, although absorption contrast was only available. It was straightforward and important to develop phase-contrast X-ray microscopy. One characteristic in the development is that quantitative phase measurement is possible through the acquisition of phase-contrast images under a specific procedure, thanks to digital X-ray image detectors...
April 18, 2017: Microscopy
Nicolas Brodusch, Raynald Gauvin
Electron channelling is known to affect the x-ray production when an accelerated electron beam is applied to a crystalline material and is highly dependent on the local crystal orientation. This effect, unless very long counting time are used, is barely noticeable on x-ray energy spectra recorded with conventional silicon drift detectors (SDD) located at a small elevation angle. However, the very high count rates provided by the new commercially available annular SDDs permit now to observe this effect routinely and may, in some circumstances, hide the true elemental x-ray variations due to the local true specimen composition...
April 18, 2017: Journal of Microscopy
R S Bradley, Y Liu, T L Burnett, X Zhou, S B Lyon, P J Withers, A Gholinia, T Hashimoto, D Graham, S R Gibbon, B Hornberger
An experimental protocol (workflow) has been developed for time-lapse x-ray nanotomography (nano-CT) imaging of environmentally driven morphological changes to materials. Two case studies are presented. First, the leaching of nanoparticle corrosion inhibitor pigment from a polymer coating was followed over 14 days, while in the second case the corrosion damage to an AA2099 aluminium alloy was imaged over 12 hours. The protocol includes several novel aspects relevant to nano-CT with the use of a combination of x-ray absorption and phase contrast data to provide enhanced morphological and composition information, and hence reveal the best information to provide new insights into the changes of different phases over time...
April 17, 2017: Journal of Microscopy
Bin Ma, Alejandro Fernandez-Martinez, Sylvain Grangeon, Christophe Tournassat, Nathaniel Findling, Francis Claret, Ayumi Koishi, Nicolas C M Marty, Delphine Tisserand, Sarah Bureau, Eduardo Salas-Colera, Erik Elkaïm, Carlo Marini, Laurent Charlet
Layered double hydroxides (LDHs) have been considered as effective phases for the remediation of aquatic environments, to remove anionic contaminants mainly through anion exchange mechanisms. Here, a combination of batch isotherm experiments and X-ray techniques was used to examine molybdate (MoO4(2-)) sorption mechanisms on CaAl LDHs with increasing loadings of molybdate. Advanced modeling of aqueous data shows that the sorption isotherm can be interpreted by three retention mechanisms, including two types of edge sites complexes, interlayer anion exchange, and CaMoO4 precipitation...
April 27, 2017: Environmental Science & Technology
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