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https://www.readbyqxmd.com/read/28821590/three-dimensional-analysis-of-chloroplast-structures-associated-with-virus-infection
#1
Xuejiao Jin, Zhihao Jiang, Kun Zhang, Pengfei Wang, Xiuling Cao, Ning Yue, Xueting Wang, Xuan Zhang, Yunqin Li, Dawei Li, Byung-Ho Kang, Yongliang Zhang
Chloroplasts are multifunctional organelles whose morphology is affected by environmental stresses. Although the three-dimensional (3D) architecture of thylakoid membranes has been reported previously, a 3D visualization of chloroplast under stress has not been explored. In this work, we used a positive-strand RNA [(+)RNA] virus, Barley stripe mosaic virus (BSMV) to observe chloroplast structural changes during infection by electron tomography (ET). The analyses revealed remodeling of the chloroplast membranes, characterized by the clustering of outer membrane-invaginated spherules in inner membrane-derived packets...
August 18, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28815603/registration-of-phase-contrast-images-in-propagation-based-x-ray-phase-tomography
#2
L Weber, A Hänsch, U Wolfram, A Pacureanu, P Cloetens, F Peyrin, S Rit, M Langer
X-ray phase tomography aims at reconstructing the 3D electron density distribution of an object. It offers enhanced sensitivity compared to attenuation-based X-ray absorption tomography. In propagation-based methods, phase contrast is achieved by letting the beam propagate after interaction with the object. The phase shift is then retrieved at each projection angle, and subsequently used in tomographic reconstruction to obtain the refractive index decrement distribution, which is proportional to the electron density...
August 16, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/28811995/agreement-between-gamma-passing-rates-using-computed-tomography-in-radiotherapy-and-secondary-cancer-risk-prediction-from-more-advanced-dose-calculated-models
#3
Abdulhamid Chaikh, Jacques Balosso
BACKGROUND: During the past decades, in radiotherapy, the dose distributions were calculated using density correction methods with pencil beam as type 'a' algorithm. The objectives of this study are to assess and evaluate the impact of dose distribution shift on the predicted secondary cancer risk (SCR), using modern advanced dose calculation algorithms, point kernel, as type 'b', which consider change in lateral electrons transport. METHODS: Clinical examples of pediatric cranio-spinal irradiation patients were evaluated...
June 2017: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28811642/octahedron-iron-oxide-nanocrystals-prohibited-clostridium-difficile-spore-germination-and-attenuated-local-and-systemic-inflammation
#4
Wei-Ting Lee, Ya-Na Wu, Yi-Hsuan Chen, Shang-Rung Wu, Tsai-Miao Shih, Tsung-Ju Li, Li-Xing Yang, Chen-Sheng Yeh, Pei-Jane Tsai, Dar-Bin Shieh
Clinical management of Clostridium difficile infection is still far from satisfactory as bacterial spores are resistant to many chemical agents and physical treatments. Certain types of nanoparticles have been demonstrated to exhibit anti-microbial efficacy even in multi-drug resistance bacteria. However, most of these studies failed to show biocompatibility to the mammalian host cells and no study has revealed in vivo efficacy in C. difficile infection animal models. The spores treated with 500 µg/mL Fe3-δO4 nanoparticles for 20 minutes, 64% of the spores were inhibited from transforming into vegetative cells, which was close to the results of the sodium hypochlorite-treated positive control...
August 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28810122/crystal-face-distributions-and-surface-site-densities-of-two-synthetic-goethites-implications-for-adsorption-capacities-as-a-function-of-particle-size
#5
Kenneth J T Livi, Mario Villalobos, Rowan K Leary, Maria Varela, Jon Barnard, Milton Villacís-García, Rodolfo Zanella, Anna Goodridge, Paul A Midgley
Two synthetic goethites of varying crystal sizes distributions were analyzed by BET, conventional TEM, cryo-TEM, atomic resolution STEM and HRTEM, and electron tomography in order to determine the effects of crystal size, shape, and atomic scale surface roughness on their adsorption capacities. The two samples were determined by BET to have very different site densities based on CrVI adsorption experiments. Model specific surfaces areas generated from TEM observations showed that, based on size and shape, there should be little difference in their adsorption capacities...
August 15, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28809471/3d-analysis-of-fuel-cell-electrocatalyst-degradation-on-alternate-carbon-supports
#6
Brian T Sneed, David A Cullen, Kimberly S Reeves, Ondrej E Dyck, David A Langlois, Rangachary Mukundan, Rodney L Borup, Karren L More
Understanding the mechanisms associated with Pt/C electrocatalyst degradation in proton exchange membrane fuel cell (PEMFC) cathodes is critical for the future development of higher-performing materials; however, there is a lack of information regarding Pt coarsening under PEMFC operating conditions within the cathode catalyst layer. We report a direct and quantitative 3D study of Pt dispersions on carbon supports (high surface area carbon (HSAC), Vulcan XC-72, and graphitized carbon) with varied surface areas, graphitic character, and Pt loadings ranging from 5-40 wt...
August 15, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28808085/sub-mitochondrial-localization-of-genetic-tagged-mib-interacting-partners-mic19-mic60-and-sam50
#7
Mira Sastri, Manjula Darshi, Mason Mackey, Ranjan Ramachandra, Saeyeon Ju, Sebastien Phan, Stephen Adams, Kathryn Stein, Christopher R Douglas, Jiwan John Kim, Mark H Ellisman, Susan S Taylor, Guy A Perkins
Each mitochondrial compartment contains varying protein compositions that underlie a diversity of localized functions. Insights into the localization of mitochondrial intermembrane space bridging (MIB) components will have an impact on our understanding of mitochondrial architecture, dynamics and function. Using the novel visualizable genetic tags miniSOG and APEX2 in cultured mouse cardiac and human astrocyte cell lines and electron tomography, we have mapped at nanoscale resolution three key MIB components: Mic19, Mic60 and Sam50, in the environment of structural landmarks such as cristae and crista junctions (CJs)...
August 14, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28799676/morphology-visualization-of-irregular-shape-bacteria-by-electron-holography-and-tomography
#8
Eduardo Ortega, Jesús Cantu-Valle, Germán Plascencia-Villa, Sandra Vergara, Fernando Mendoza-Santoyo, Alejandra Londono-Calderon, Ulises Santiago, Arturo Ponce
In the current work, irregular morphology of Staphylococcus aureus bacteria has been visualized by phase retrieval employing off-axis electron holography (EH) and 3D reconstruction electron tomography using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Bacteria interacting with gold nanoparticles (AuNP) acquired a shrunken or irregular shape due to air dehydration processing. STEM imaging shows the attachment of AuNP on the surface of cells and suggests an irregular 3D morphology of the specimen...
August 11, 2017: Microscopy Research and Technique
https://www.readbyqxmd.com/read/28797951/subsampling-and-inpainting-approaches-for-electron-tomography
#9
Toby Sanders, Christian Dwyer
With the aim of addressing the issue of sample damage during electron tomography data acquisition, we propose a number of new reconstruction strategies based on subsampling (which uses only a subset of a full image) and inpainting (recovery of a full image from subsampled one). We point out that the total-variation (TV) inpainting model commonly used to inpaint subsampled images may be inappropriate for 2D projection images of typical TEM specimens. Thus, we propose higher-order TV (HOTV) inpainting, which accommodates the fact that projection images may be inherently smooth, as a more suitable image inpainting scheme...
August 3, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/28796750/in-vivo-electron-paramagnetic-resonance-tooth-dosimetry-dependence-of-radiation-induced-signal-amplitude-on-the-enamel-thickness-and-surface-area-of-ex-vivo-human-teeth
#10
Michitaka Umakoshi, Ichiro Yamaguchi, Hiroshi Hirata, Naoki Kunugita, Benjamin B Williams, Harold M Swartz, Minoru Miyake
In vivo L-band electron paramagnetic resonance tooth dosimetry is a newly developed and very promising method for retrospective biodosimetry in individuals who may have been exposed to significant levels of ionizing radiation. The present study aimed to determine the relationships among enamel thickness, enamel area, and measured electron paramagnetic resonance signal amplitude with a view to improve the quantitative accuracy of the dosimetry technique. Ten isolated incisors were irradiated using well-characterized doses, and their radiation-induced electron paramagnetic resonance signals were measured...
August 7, 2017: Health Physics
https://www.readbyqxmd.com/read/28795133/performance-of-18-f-flutemetamol-amyloid-imaging-against-the-neuritic-plaque-component-of-cerad-and-the-current-2012-nia-aa-recommendations-for-the-neuropathologic-diagnosis-of-alzheimer-s-disease
#11
Stephen Salloway, Jose E Gamez, Upinder Singh, Carl H Sadowsky, Teresa Villena, Marwan N Sabbagh, Thomas G Beach, Ranjan Duara, Adam S Fleisher, Kirk A Frey, Zuzana Walker, Arvinder Hunjan, Yavir M Escovar, Marc E Agronin, Joel Ross, Andrea Bozoki, Mary Akinola, Jiong Shi, Rik Vandenberghe, Milos D Ikonomovic, Paul F Sherwin, Gill Farrar, Adrian P L Smith, Christopher J Buckley, Dietmar Rudolf Thal, Michelle Zanette, Craig Curtis
INTRODUCTION: Performance of the amyloid tracer [(18)F]flutemetamol was evaluated against three pathology standard of truth (SoT) measures including neuritic plaques (CERAD "original" and "modified" and the amyloid component of the 2012 NIA-AA guidelines). METHODS: After [(18)F]flutemetamol imaging, 106 end-of-life patients who died underwent postmortem brain examination for amyloid plaque load. Blinded positron emission tomography scan interpretations by five independent electronically trained readers were compared with pathology measures...
2017: Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring
https://www.readbyqxmd.com/read/28794474/porosity-evolution-at-the-brittle-ductile-transition-in-the-continental-crust-implications-for-deep-hydro-geothermal-circulation
#12
M Violay, M J Heap, M Acosta, C Madonna
Recently, projects have been proposed to engineer deep geothermal reservoirs in the ductile crust. To examine their feasibility, we performed high-temperature (up to 1000 °C), high-pressure (130 MPa) triaxial experiments on granite (initially-intact and shock-cooled samples) in which we measured the evolution of porosity during deformation. Mechanical data and post-mortem microstuctural characterisation (X-ray computed tomography and scanning electron microscopy) indicate that (1) the failure mode was brittle up to 900 °C (shear fracture formation) but ductile at 1000 °C (no strain localisation); (2) only deformation up to 800 °C was dilatant; (3) deformation at 900 °C was brittle but associated with net compaction due to an increase in the efficiency of crystal plastic processes; (4) ductile deformation at 1000 °C was compactant; (5) thermally-shocking the granite did not influence strength or failure mode...
August 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28794042/palmitoylation-contributes-to-membrane-curvature-in-influenza-a-virus-assembly-and-hemagglutinin-mediated-membrane-fusion
#13
Petr Chlanda, Elena Mekhedov, Hang Waters, Alexander Sodt, Cindi Schwartz, Vinod Nair, Paul S Blank, Joshua Zimmerberg
The highly conserved cytoplasmic tail of influenza virus glycoprotein hemagglutinin (HA) contains three cysteines, post-translationally modified by covalently bound fatty acids. While viral HA acylation is crucial in virus replication, its physico-chemical role is unknown. We used virus-like particles (VLP) to study the effect of acylation on morphology, protein incorporation, lipid composition, and membrane fusion. De-acylation interrupted HA-M1 interactions since de-acylated mutant HA fail to incorporate an M1 layer within spheroidal VLP, and filamentous particles incorporated increased numbers of neuraminidase (NA)...
August 9, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28781999/accelerating-electron-tomography-reconstruction-algorithm-icon-with-gpu
#14
Yu Chen, Zihao Wang, Jingrong Zhang, Lun Li, Xiaohua Wan, Fei Sun, Fa Zhang
Electron tomography (ET) plays an important role in studying in situ cell ultrastructure in three-dimensional space. Due to limited tilt angles, ET reconstruction always suffers from the "missing wedge" problem. With a validation procedure, iterative compressed-sensing optimized NUFFT reconstruction (ICON) demonstrates its power in the restoration of validated missing information for low SNR biological ET dataset. However, the huge computational demand has become a major problem for the application of ICON...
2017: Biophysics Reports
https://www.readbyqxmd.com/read/28781998/the-advent-of-structural-biology-in-situ-by-single-particle-cryo-electron-tomography
#15
Jesús G Galaz-Montoya, Steven J Ludtke
Single particle tomography (SPT), also known as subtomogram averaging, is a powerful technique uniquely poised to address questions in structural biology that are not amenable to more traditional approaches like X-ray crystallography, nuclear magnetic resonance, and conventional cryoEM single particle analysis. Owing to its potential for in situ structural biology at subnanometer resolution, SPT has been gaining enormous momentum in the last five years and is becoming a prominent, widely used technique. This method can be applied to unambiguously determine the structures of macromolecular complexes that exhibit compositional and conformational heterogeneity, both in vitro and in situ...
2017: Biophysics Reports
https://www.readbyqxmd.com/read/28774144/micromechanical-properties-of-a-new-polymeric-microcapsule-for-self-healing-cementitious-materials
#16
Leyang Lv, Erik Schlangen, Zhengxian Yang, Feng Xing
Self-healing cementitious materials containing a microencapsulated healing agent are appealing due to their great application potential in improving the serviceability and durability of concrete structures. In this study, poly(phenol-formaldehyde) (PF) microcapsules that aim to provide a self-healing function for cementitious materials were prepared by an in situ polymerization reaction. Size gradation of the synthesized microcapsules was achieved through a series of sieving processes. The shell thickness and the diameter of single microcapsules was accurately measured under environmental scanning electron microscopy (ESEM)...
December 20, 2016: Materials
https://www.readbyqxmd.com/read/28773792/in-vivo-evaluation-of-bulk-metallic-glasses-for-osteosynthesis-devices
#17
Kazuhiro Imai, Sachiko Hiromoto
Bulk metallic glasses (BMGs) show higher strength and lower Young's modulus than Ti-6Al-4V alloy and SUS 316L stainless steel. This study aimed to perform in vivo evaluations of Zr65Al7.5Ni10Cu17.5 BMGs for osteosynthesis devices. In the study for intramedullary implants, osteotomies of the femoral bones were performed in male Wistar rats and were stabilized with Zr65Al7.5Ni10Cu17.5 BMGs, Ti-6Al-4V alloy, or 316L stainless steel intramedullary nails for 12 weeks. In the study for bone surface implants, Zr65Al7...
August 9, 2016: Materials
https://www.readbyqxmd.com/read/28772572/effect-of-energy-input-on-microstructure-and-mechanical-properties-of-titanium-aluminide-alloy-fabricated-by-the-additive-manufacturing-process-of-electron-beam-melting
#18
Ashfaq Mohammad, Abdulrahman M Alahmari, Muneer Khan Mohammed, Ravi Kottan Renganayagalu, Khaja Moiduddin
Titanium aluminides qualify adequately for advanced aero-engine applications in place of conventional nickel based superalloys. The combination of high temperature properties and lower density gives an edge to the titanium aluminide alloys. Nevertheless, challenges remain on how to process these essentially intermetallic alloys in to an actual product. Electron Beam Melting (EBM), an Additive Manufacturing Method, can build complex shaped solid parts from a given feedstock powder, thus overcoming the shortcomings of the conventional processing techniques such as machining and forging...
February 21, 2017: Materials
https://www.readbyqxmd.com/read/28772453/idealized-vs-realistic-microstructures-an-atomistic-simulation-case-study-on-%C3%AE-%C3%AE-microstructures
#19
Aruna Prakash, Erik Bitzek
Single-crystal Ni-base superalloys, consisting of a two-phase γ/ γ ' microstructure, retain high strengths at elevated temperatures and are key materials for high temperature applications, like, e.g., turbine blades of aircraft engines. The lattice misfit between the γ and γ ' phases results in internal stresses, which significantly influence the deformation and creep behavior of the material. Large-scale atomistic simulations that are often used to enhance our understanding of the deformation mechanisms in such materials must accurately account for such misfit stresses...
January 23, 2017: Materials
https://www.readbyqxmd.com/read/28772369/comparison-of-maraging-steel-micro-and-nanostructure-produced-conventionally-and-by-laser-additive-manufacturing
#20
Eric A Jägle, Zhendong Sheng, Philipp Kürnsteiner, Sörn Ocylok, Andreas Weisheit, Dierk Raabe
Maraging steels are used to produce tools by Additive Manufacturing (AM) methods such as Laser Metal Deposition (LMD) and Selective Laser Melting (SLM). Although it is well established that dense parts can be produced by AM, the influence of the AM process on the microstructure-in particular the content of retained and reversed austenite as well as the nanostructure, especially the precipitate density and chemistry, are not yet explored. Here, we study these features using microhardness measurements, Optical Microscopy, Electron Backscatter Diffraction (EBSD), Energy Dispersive Spectroscopy (EDS), and Atom Probe Tomography (APT) in the as-produced state and during ageing heat treatment...
December 24, 2016: Materials
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