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X ray phase contrast

Heyang Thomas Li, Andrew M Kingston, Glenn R Myers, Levi Beeching, Adrian P Sheppard
Near-field x-ray refraction (phase) contrast is unavoidable in many lab-based micro-CT imaging systems. Quantitative analysis of x-ray refraction (a.k.a. phase retrieval) is in general an under-constrained problem. Regularizing assumptions may not hold true for interesting samples; popular single-material methods are inappropriate for heterogeneous samples, leading to undesired blurring and/or over-sharpening. In this paper, we constrain and solve the phase-retrieval problem for heterogeneous objects, using the Alvarez-Macovski model for x-ray attenuation...
January 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Lorenzo Massimi, Francesco Brun, Michela Fratini, Inna Bukreeva, Alessia Cedola
The suppression of ring artifacts in X-ray computed tomography (CT) is a required step in practical applications and it is commonly faced by introducing refined digital low pass filters within the reconstruction process. However, for the specific case of synchrotron in-line phase contrast CT, these filters introduce a new ringing artifact when simultaneously imaging pure phase objects and elements having a non-negligible absorption coefficient. Ringing originates at sharp interfaces due to the truncation of spatial high frequencies and it severely affects qualitative and quantitative analysis of the reconstructed slices...
January 11, 2018: Physics in Medicine and Biology
Fulvia Arfelli, Alberto Astolfo, Luigi Rigon, Ralf Hendrik Menk
Unlike conventional x-ray attenuation one of the advantages of phase contrast x-ray imaging is its capability of extracting useful physical properties of the sample. In particular the possibility to obtain information from small angle scattering about unresolvable structures with sub-pixel resolution sensitivity has drawn attention for both medical and material science applications. We report on a novel algorithm for the analyzer based x-ray phase contrast imaging modality, which allows the robust separation of absorption, refraction and scattering effects from three measured x-ray images...
January 10, 2018: Scientific Reports
Katrin Ehlert, Christian Mikutta, Yuan Jin, Ruben Kretzschmar
X-ray amorphous Fe(III)-As(V) coprecipitates are common initial products of oxidative As- and Fe-bearing sulfide weathering, and often control As solubility in mine wastes or mining-impacted soils. The formation conditions of these solids may exert a major control on their mineralogical composition and, hence, As release in the gastric tract of humans after incidental ingestion of As-contaminated soil. Here, we synthesized a set of 35 Fe(III)-As(V) coprecipitates as a function of pH (1.5-8) and initial molar Fe/As ratio (0...
January 4, 2018: Environmental Science & Technology
Shengkun Yao, Yunbing Zong, Xu Huang, Yang Liu, Ningqiang Gong, Jianhua Zhang, Ziqing Li, Feng Cao, Xiangcheng Wang, Xing-Jie Liang, Huaidong Jiang
Cardiovascular diseases are closely related to structural blood capillaries lesions. Herein, microscopic investigations of mouse blood capillaries were performed at multiple spatial resolution by using synchrotron X-ray in-line phase contrast tomography and scanning transmission X-ray microscopy (STXM). The chemically fixed blood capillaries without any contrast agents were selected. For the first time, a periodic bamboo-shaped structure was observed at nanoscale resolution by STXM, and the three-dimensional tomographic slices at sub-micrometer resolution further confirmed the periodic wave profile of the blood capillaries...
December 1, 2017: Biomedical Optics Express
Vikram J Pansare, Aditya Rawal, Aaron Goodwin, Ron Beyerinck, Robert K Prud'homme, Dwayne T Friesen, Michael Grass, Annie Muske-Dukes, David T Vodak
We report the development of a new Spray-drying and Nanoparticle Assembly Process (SNAP), that enables the formation of stable, yet rapidly dissolving, sub-200 nm nano-crystalline particles within a high Tg glassy matrix. SNAP expands the class of drugs that Spray Dried Dispersion (SDD) processing can address to encompass highly crystalline, but modestly hydrophobic drugs that are difficult to process by conventional SDD. The process integrates rapid precipitation and spray drying within a custom designed nozzle to produce high supersaturations and precipitation of the drug and high Tg glassy polymer...
December 15, 2017: Molecular Pharmaceutics
Masahiro Shimizu, Makoto Umeki, Susumu Arai
Practical applications of Li-S and Li-air batteries require the morphology of the Li metal negative electrode during charge/discharge (i.e., Li-deposition/dissolution) cycling to be precisely controlled. Herein, we used magnesium bis(trifluoromethanesulfonyl)amide [Mg(TFSA)2] as an electrolyte additive to suppress the growth of Li dendrites, utilizing the occurrence of an alloying reaction between the initially substrate-deposited Mg and the subsequently deposited Li. Notably, no metallic Mg formation and no change in Li deposition morphology were observed at an electrolyte composition of 0...
December 14, 2017: Physical Chemistry Chemical Physics: PCCP
Lena Trotochaud, Ashley R Head, Sven Pletincx, Osman Karslıoğlu, Yi Yu, Astrid Waldner, Line Kyhl, Tom Hauffman, Herman Terryn, Bryan W Eichhorn, Hendrik Bluhm
We use ambient pressure X-ray photoelectron spectroscopy (APXPS) to study chemical changes, including hydroxylation and water adsorption, at copper oxide surfaces from ultra-high vacuum to ambient relative humidities of ~5%. Polycrystalline CuO and Cu2O surfaces were prepared by selective oxidation of metallic copper foils. For both oxides, hydroxylation occurs readily, even at high vacuum conditions. Hydroxylation on both oxides plateaus near ~0.01% relative humidity (RH) at a coverage of ~1 monolayer. In contrast to previous studies, neither oxide shows significant accumulation of molecular water; rather, both surfaces show a high affinity for adventitious carbon contaminants...
December 7, 2017: Journal of Physical Chemistry. B
Andrea Cau, Vincent Beyrand, Dennis F A E Voeten, Vincent Fernandez, Paul Tafforeau, Koen Stein, Rinchen Barsbold, Khishigjav Tsogtbaatar, Philip J Currie, Pascal Godefroit
Maniraptora includes birds and their closest relatives among theropod dinosaurs. During the Cretaceous period, several maniraptoran lineages diverged from the ancestral coelurosaurian bauplan and evolved novel ecomorphologies, including active flight, gigantism, cursoriality and herbivory. Propagation X-ray phase-contrast synchrotron microtomography of a well-preserved maniraptoran from Mongolia, still partially embedded in the rock matrix, revealed a mosaic of features, most of them absent among non-avian maniraptorans but shared by reptilian and avian groups with aquatic or semiaquatic ecologies...
December 21, 2017: Nature
Wenda Wang, Mark C Staub, Tian Zhou, Derrick M Smith, Hao Qi, Eric D Laird, Shan Cheng, Christopher Y Li
Crystallization is incommensurate with nanoscale curved space due to the lack of three dimensional translational symmetry of the latter. Herein, we report the formation of single-crystal-like, nanosized polyethylene (PE) capsules using a miniemulsion solution crystallization method. The miniemulsion was formed at elevated temperatures using PE organic solution as the oil phase and sodium dodecyl sulfate as the surfactant. Subsequently, cooling the system stepwisely for controlled crystallization led to the formation of hollow, nanosized PE crystalline capsules, which are named as crystalsomes since they mimic the classical self-assembled structures such as liposome, polymersome and colloidosome...
December 6, 2017: Nanoscale
Yongjin Sung, Rajiv Gupta, Brandon Nelson, Shuai Leng, Cynthia H McCollough, William S Graves
X-ray phase-contrast imaging (XPCI) overcomes the problem of low contrast between different soft tissues achieved in conventional x-ray imaging by introducing x-ray phase as an additional contrast mechanism. This work describes a compact x-ray light source (CXLS) and compares, via simulations, the high quality XPCI results that can be produced from this source to those produced using a microfocus x-ray source. The simulation framework is first validated using an image acquired with a microfocus-source, propagation-based XPCI (PB-XPCI) system...
October 2017: Journal of Medical Imaging
Huajie Han, Renfang Hu, Faiz Wali, Zhao Wu, Kun Gao, Shenghao Wang, Yonggang Gu, Yi Jin, Chao Zhai
PURPOSE: In this paper, we propose a novel method for human body composition measurement, especially for the bone mineral density (BMD) measurement. The proposed method, using the absorption and differential phase information retrieved from X-ray grating-based interferometer (XGBI) to measure the BMD, has potential to replace dual-energy X-ray absorptiometry (DEXA), which is currently widely used for body composition measurement. METHODS: The DEXA method employs two absorption images acquired at two different X-ray spectra (high energy and low energy) to calculate the human body composition...
November 2017: Physica Medica: PM
Christopher Weis, Christian Sternemann, Valerio Cerantola, Christoph J Sahle, Georg Spiekermann, Manuel Harder, Yury Forov, Alexander Kononov, Robin Sakrowski, Hasan Yavaş, Metin Tolan, Max Wilke
Iron-bearing carbonates are candidate phases for carbon storage in the deep Earth and may play an important role for the Earth's carbon cycle. To elucidate the properties of carbonates at conditions of the deep Earth, we investigated the pressure driven magnetic high spin to low spin transition of synthetic siderite FeCO3 and magnesiosiderite (Mg0.74Fe0.26)CO3 single crystals for pressures up to 57 GPa using diamond anvil cells and x-ray Raman scattering spectroscopy to directly probe the iron 3d electron configuration...
November 28, 2017: Scientific Reports
Nizar Bchellaoui, Zain Hayat, Mohamed Mami, Rachida Dorbez-Sridi, Abdel Illah El Abed
The fabrication of mesoporous silica microcapsules with a highly controlled particle size ranging in the micrometer size presents a major challenge in many academic and industrial research areas, such as for the developement of smart drug delivery systems with a well controlled loading and release of (bio)active molecules. Many studies based on the solvent evaporation or solvent diffusion methods have been developed during the last two decades in order to control the particle size, which is often found to range at a sub-micrometer scale...
November 27, 2017: Scientific Reports
C M Disney, K Madi, A J Bodey, P D Lee, J A Hoyland, M J Sherratt
Intervertebral disc degeneration (IVDD) is linked to low back pain. Microstructural changes during degeneration have previously been imaged using 2D sectioning techniques and 3D methods which are limited to small specimens and prone to inducing artefacts from sample preparation. This study explores micro computed X-ray tomography (microCT) methods with the aim of resolving IVD 3D microstructure whilst minimising sample preparation artefacts. Low X-ray absorption contrast in non-mineralised tissue can be enhanced using staining and phase contrast techniques...
November 24, 2017: Scientific Reports
Yury Ivanishko, Alberto Bravin, Sergey Kovalev, Polina Lisutina, Mikhail Lotoshnikov, Alberto Mittone, Sergey Tkachev, Marina Tkacheva
Purpose: The intracranial three-dimensional (3D) visualization of the whole volume of the eyeball at micrometric resolution has not been achieved yet either in clinical nor in preclinical diagnostic research. Overcoming this limitation may provide a new tool for clinical and preclinical studies of different pathologies of the various sections of the eye. The aim of this work is to give the first insight of a volumetric visualization at the high resolution of the entire enucleated and intracranial postmortem rabbit eyeballs...
November 1, 2017: Investigative Ophthalmology & Visual Science
Marcus J Kitchen, Genevieve A Buckley, Timur E Gureyev, Megan J Wallace, Nico Andres-Thio, Kentaro Uesugi, Naoto Yagi, Stuart B Hooper
Phase-contrast X-ray imaging can improve the visibility of weakly absorbing objects (e.g. soft tissues) by an order of magnitude or more compared to conventional radiographs. Combining phase retrieval with computed tomography (CT) can increase the signal-to-noise ratio (SNR) by up to two orders of magnitude over conventional CT at the same radiation dose, without loss of image quality. Our experiments reveal that as the radiation dose decreases, the relative improvement in SNR increases. We show that this enhancement can be traded for a reduction in dose greater than the square of the gain in SNR...
November 21, 2017: Scientific Reports
Christina N Banti, Constantina Papatriantafyllopoulou, Anastasios J Tasiopoulos, Sotiris K Hadjikakou
The non steroidal anti-inflammatory drugs (NSAID's)-silver(I) metallodrugs of aspirin (aspH), salicylic acid (salH2), naproxen (napH) acid or p-hydrobenzoic acid (pHbzaH) and the mitochondriotropic triphenylarsine (tpAs) with the formulae [Ag(asp)(tpAs)3] (1), [Ag(salH)(tpAs)3] (2), [Ag(nap)(tpAs)3] (3) and {[Ag(pHbza)(tpAs)3]∙(dmf)} (4) and [Ag(tpAs)3(NO3)] (5) have been synthesized and characterized by m.p., FT-IR, UV-vis and (1)H NMR, spectroscopic techniques and X-ray crystallography. The in vitro cytotoxic activity of 1-5 against human breast adenocarcinoma cancer cells: MCF-7 (positive to estrogen receptors (ERs)) and MDA-MB-231 (negative to estrogen receptors (ERs)) was evaluated...
November 10, 2017: European Journal of Medicinal Chemistry
Anthony R Bradley, Aude Echalier, Michael Fairhead, Claire Strain-Damerell, Paul Brennan, Alex N Bullock, Nicola A Burgess-Brown, Elisabeth P Carpenter, Opher Gileadi, Brian D Marsden, Wen Hwa Lee, Wyatt Yue, Chas Bountra, Frank von Delft
The ongoing explosion in genomics data has long since outpaced the capacity of conventional biochemical methodology to verify the large number of hypotheses that emerge from the analysis of such data. In contrast, it is still a gold-standard for early phenotypic validation towards small-molecule drug discovery to use probe molecules (or tool compounds), notwithstanding the difficulty and cost of generating them. Rational structure-based approaches to ligand discovery have long promised the efficiencies needed to close this divergence; in practice, however, this promise remains largely unfulfilled, for a host of well-rehearsed reasons and despite the huge technical advances spearheaded by the structural genomics initiatives of the noughties...
November 8, 2017: Essays in Biochemistry
Joydip De, Santosh Prasad Gupta, Indu Bala, Sandeep Kumar, Santanu Kumar Pal
Five novel columnar liquid crystalline compounds (4.1-4.5) consisting of a central anthraquinone core carrying four alkoxy chains (R = n-C6H13, n-C8H17, n-C10H21, n-C12H25, and 3,7-dimethyl octyl) with two diagonally opposite 1-ethynyl-4-pentylbenzene units were synthesized, and their phase transitions were investigated between changes in the molecular structure and their self-assembly into the columnar mesophases. Small and wide-angle X-ray scattering (SAXS/WAXS) studies were performed to deduce the exact nature of the mesophases, and their corresponding electron density maps were derived from the intensities of the peaks observed in the diffraction patterns...
November 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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