Suresh Narayanan

Argonne National Laboratory

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Alec Sandy

Argonne National Laboratory

113

Zhang Jiang

Argonne National Laboratory

Qingteng Zhang

Argonne National Laboratory

Laurence Lurio

Northern Illinois University

Mark D. Foster

University of Akron

Eric M. Đufresne

Argonne National Laboratory

Michael Sprung

Deutsches Elektronen-Synchrotron DESY

S. K. Sinha

University of California, San Diego

Robert L. Leheny

Johns Hopkins University

S. G. J. Mochrie

Yale University

Cooperative Institutions

Argonne National Laboratory

217

University of Chicago

National Institute of Standards and Technology

Cornell University

Lawrence Berkeley National Laboratory

Brookhaven National Laboratory

Northwestern University

University of Illinois Urbana-Champaign

Massachusetts Institute of Technology

University of Akron

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Relaxation

Jaypee Brothers Medical Publishers (P) Ltd. eBooks (2005)

Suresh Narayanan

10.5005/jp/books/10958_6

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Enhancement of in-plane spatial resolution in volumetric computed tomography with focal spot wobbling – Overcoming the constraint on number of projection views per gantry rotation

Journal of X-Ray Science and Technology (2010)

Xiangyang Tang Suresh Narayanan Jiang Hsieh Jed D. Pack Scott M. Mcolash

The spatial resolution of diagnostic Computed Tomography (CT) has increased substantially, and 3D isotropic sub-millimeter spatial resolution in both axial and helical scan modes is routinely available in the clinic. However, driven by advanced clinical applications, the pursuit for higher spatial resolution and free of aliasing artifacts in diagnostic CT has never stopped. A method to accommodate focal spot wobbling at an arbitrary number of projection views per gantry rotation in CT is presented and evaluated here. The method employs a beta-correction scheme in the row-wise fan-to-parallel rebinning to transform the native cone beam geometry into the cone-parallel geometry under which existing 3D weighted cone beam filtered backprojection algorithms can be utilized for image reconstruction. The experimental evaluation shows that the row-wise fan-to-parallel rebinning with the beta-correction can increase the quantitative in-plane spatial resolution (Modulation Transfer Function) substantially, while the visual spatial resolution can be enhanced significantly. Consequently, the architectural designers of CT scanners are no longer constrained to choosing the number of projection views per rotation determined by gantry geometry. Instead, they can choose the number of projection views per rotation to optimize the trade-offs between in-plane spatial resolution and noise characteristics. Therefore, the presented method is of practical relevance in the architectural design of state-of-the-art diagnostic CT.

Projection plane

10.3233/xst-2010-025800258

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Citations (1)

Multiple dynamical regimes in colloidal polymer suspension with competing interaction

Bulletin of the American Physical Society (2014)

Sunita Srivastava Suhasini Kishore Suresh Narayanan Surita R. Bhatia

Suspension

Colloidal particle

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Structure and Entanglement Factors on Dynamics of Polymer-Grafted Nanoparticles

ACS Macro Letters (2016)

Siqi Liu Erkan Şenses Yang Jiao Suresh Narayanan Pinar Akcora

Nanoparticles functionalized with long polymer chains at low graft density are interesting systems to study structure-dynamic relationships in polymer nanocomposites since they are shown to aggregate into strings in both solution and melts and also into spheres and branched aggregates in the presence of free polymer chains. This work investigates structure and entanglement effects in composites of polystyrene-grafted iron oxide nanoparticles by measuring particle relaxations using X-ray photon correlation spectroscopy. Particles within highly ordered strings and aggregated systems experience a dynamically heterogeneous environment displaying hyperdiffusive relaxation commonly observed in jammed soft glassy systems. Furthermore, particle dynamics is diffusive for branched aggregated structures which could be caused by less penetration of long matrix chains into brushes. These results suggest that particle motion is dictated by the strong interactions of chains grafted at low density with the host matrix polymer.

Polystyrene

Particle (ecology)

Polymer nanocomposite

10.1021/acsmacrolett.6b00089

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Citations (45)

Structure and Dynamics of Interacting Nanoparticles in Semidilute Polymer Solutions

Macromolecules (2016)

Ryan Poling‐Skutvik Katrina Irene S. Mongcopa Antonio Faraone Suresh Narayanan Jacinta C. Conrad

We investigate the structure and dynamics of silica nanoparticles and polymer chains in semidilute solutions of high molecular weight polystyrene in 2-butanone to determine the effect of long-range interparticle interactions on the coupling between particle and polymer dynamics. Particles at concentrations of 1–10 wt % are well dispersed in the semidilute polymer solutions and exhibit long-range electrostatic repulsions between particles. Because the particles are comparably sized to the radius of gyration of the polymer, the particle dynamics is predicted to couple to that of the polymer. We verify that the polymer structure and dynamics are not significantly affected by the particles, indicating that the particle–polymer coupling does not change with increasing particle loading. We find that the coupling between the dynamics of comparably sized particles and polymer results in subdiffusive particle dynamics, as expected. Over the interparticle distance, however, the particle dynamics is hindered and not fully described by the relaxation of the surrounding polymer chains. Instead, the particle dynamics is inversely related to the structure factor, suggesting that physical particle–polymer coupling on short length scales and interparticle interactions on long length scales both present energetic barriers to particle motion that lead to subdiffusive dynamics and de Gennes narrowing, respectively.

Radius of gyration

Particle (ecology)

Polystyrene

Hydrodynamic radius

Dynamics

Gyration

10.1021/acs.macromol.6b01277

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Citations (35)

Structure, Dynamics, and Viscoelasticity of Nanoparticle Thin Films at the Liquid-Air Interface

Bulletin of the American Physical Society (2013)

Leandra Boucheron Jacob Stanley Yeling Dai Binhua Lin Mati Meron

Dynamics

Interface (matter)

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Fabrication and heating rate study of microscopic surface electrode ion traps

New Journal of Physics (2011)

Nikos Daniilidis Suresh Narayanan Sönke Möller Robert Clark T E Lee

We report heating rate measurements in a microfabricated gold-on-sapphire surface electrode ion trap with a trapping height of approximately 240 μm. Using the Doppler recooling method, we characterize the trap heating rates over an extended region of the trap. The noise spectral density of the trap falls in the range of noise spectra reported in ion traps at room temperature. We find that during the first months of operation, the heating rates increase by approximately one order of magnitude. The increase in heating rates is largest in the ion-loading region of the trap, providing a strong hint that surface contamination plays a major role for excessive heating rates. We discuss data found in the literature and the possible relation of anomalous heating to sources of noise and dissipation in other systems, namely impurity atoms adsorbed onto metal surfaces and amorphous dielectrics.

Trap (plumbing)

10.1088/1367-2630/13/1/013032

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Citations (94)

Technology absorption and diffusion among local supporting firms in the electronics sector : explaining the divergence between Penang and the Klang Valley, Malaysia

Institut Kajian Malaysia dan Antarabangsa, Universiti Kebangsaan Malaysia eBooks (1997)

Suresh Narayanan

Divergence (linguistics)

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MPICorrelator: A parallel code for performing time correlations