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Selected Works

2019

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Articles 1 - 30 of 291

Full-Text Articles in Physics

Slowing Down Of Spin Glass Correlation Length Growth: Simulations Meet Experiments, Qiang Zhai, V. Martin-Mayor, Deborah L. Schlagel, Gregory G. Kenning, Raymond L. Orbach Oct 2019

Slowing Down Of Spin Glass Correlation Length Growth: Simulations Meet Experiments, Qiang Zhai, V. Martin-Mayor, Deborah L. Schlagel, Gregory G. Kenning, Raymond L. Orbach

Deborah L. Schlagel

The growth of the spin glass correlation length has been measured as a function of the waiting time tw on a single crystal of CuMn (6 at. %), reaching values ξ∼150 nm, larger than any other glassy correlation length measured to date. We find an aging rate dlntw/dlnξ larger than found in previous measurements, which evinces a dynamic slowing down as ξ grows. Our measured aging rate is compared with simulation results by the Janus Collaboration. After critical effects are taken into account, we find excellent agreement with the Janus data.


Complex Oscillatory Decrease With Size In Diffusivity Of {100}-Epitaxially Supported 3d Fcc Metal Nanoclusters, King C. Lai, James W. Evans Oct 2019

Complex Oscillatory Decrease With Size In Diffusivity Of {100}-Epitaxially Supported 3d Fcc Metal Nanoclusters, King C. Lai, James W. Evans

James W. Evans

Diffusion and coalescence of supported 3D metal nanoclusters (NCs) leads to Smoluchowski Ripening (SR), a key pathway for catalyst degradation. Variation of the NC diffusion coefficient, DN, with size N (in atoms) controls SR kinetics. Traditionally, a form DN ∼ N−β was assumed consistent with mean-field analysis. However, KMC simulation of a stochastic model for diffusion of {100}-epitaxially supported fcc NCs mediated by surface diffusion reveals instead a complex oscillatory decrease of DN with N. Barriers for surface diffusion of metal atoms across and between facets, along step edges, etc., in this model are selected to accurately capture behavior ...


A Diffraction Paradox: An Unusually Broad Diffraction Background Signals Ideal Graphene, Shen Chen, Michael Horn-Von Hoegen, Patricia A. Thiel, Michael C. Tringides Oct 2019

A Diffraction Paradox: An Unusually Broad Diffraction Background Signals Ideal Graphene, Shen Chen, Michael Horn-Von Hoegen, Patricia A. Thiel, Michael C. Tringides

Patricia A. Thiel

The realization of the unusual properties of 2-d materials requires the formation of large domains of single layer thickness, extending over the mesoscale. It is found that the formation of ideal graphene on SiC, contrary to textbook diffraction , is signaled by a strong bell-shaped-component (BSC) around the (00) and G(10), but not the SiC(10) spots.The BSC is also seen for graphene on metals, because single layer uniform graphene with large lateral size can also be grown. It is only seen by electron diffraction and not with X-ray or He-scattering experiments. Most likely it originates from the spatial ...


Physics Professor Receives $250k From Nsf To Help Advance Climate Science Oct 2019

Physics Professor Receives $250k From Nsf To Help Advance Climate Science

Frank Robinson

Sacred Heart University has received $252,060 from the National Science Foundation (NSF) to help advance climate science. This grant will help fund an undergraduate physics research program introducing juniors and seniors to cutting-edge scientific research, intended to bridge major gaps in climate modeling.


In Situ Investigation Of Magnetism In Metastable Phases Of Levitated Fe83b17 During Solidification, D. G. Quirinale, D. Messina, G. E. Rustan, Andreas Kreyssig, Ruslan Prozorov, Alan I. Goldman Oct 2019

In Situ Investigation Of Magnetism In Metastable Phases Of Levitated Fe83b17 During Solidification, D. G. Quirinale, D. Messina, G. E. Rustan, Andreas Kreyssig, Ruslan Prozorov, Alan I. Goldman

A. I. Goldman

In situ measurements of structure, density, and magnetization on samples of Fe83B17 using an electrostatic levitation furnace allow us to identify and correlate the magnetic and structural transitions in this system during its complex solidification process. In particular, we identify magnetic ordering in the metastable Fe23B6/ fcc Fe coherently grown structures and primitive tetragonal Fe3B metastable phase in addition to characterizing the equilibrium Fe2B phase. Our measurements demonstrate that the incorporation of a tunnel-diode oscillator circuit within an electrostatic levitation furnace enables investigations of the physical properties of high-temperature metastable structures.


Distinct Pressure Evolution Of Coupled Nematic And Magnetic Orders In Fese, Anna E. Böhmer, Karunakar Kothapalli, Wageesha T. Jayasekara, John M. Wilde, Bing Li, Aashish Sapkota, Benjamin G. Ueland, Pinaki Das, Yumin Xiao, Wenli Bi, Jiyong Zhao, E. Ercan Alp, Sergey L. Bud’Ko, Paul C. Canfield, Alan I. Goldman, Andreas Kreyssig Oct 2019

Distinct Pressure Evolution Of Coupled Nematic And Magnetic Orders In Fese, Anna E. Böhmer, Karunakar Kothapalli, Wageesha T. Jayasekara, John M. Wilde, Bing Li, Aashish Sapkota, Benjamin G. Ueland, Pinaki Das, Yumin Xiao, Wenli Bi, Jiyong Zhao, E. Ercan Alp, Sergey L. Bud’Ko, Paul C. Canfield, Alan I. Goldman, Andreas Kreyssig

A. I. Goldman

We present a microscopic study of nematicity and magnetism in FeSe over a wide temperature and pressure range using high-energy x-ray diffraction and time-domain Mössbauer spectroscopy. The low-temperature magnetic hyperfine field increases monotonically up to ∼ 6 GPa. The orthorhombic distortion initially decreases under increasing pressure but is stabilized at intermediate pressures by cooperative coupling to the pressure-induced magnetic order. Close to the reported maximum of the superconducting critical temperature at p = 6.8 GPa , the orthorhombic distortion suddenly disappears and a new tetragonal magnetic phase occurs. The pressure and temperature evolution of the structural and magnetic order parameters suggests that ...


Heisenberg Model Analysis On Inelastic Powder Neutron Scattering Data Using Parent And K Doped Bamn2as2 Samples, Mehmet Ramazanoglu, Aashish Sapkota, Abhishek Pandey, Jagat Lamsal, Douglas L. Abernathy, Jennifer L. Niedziela, Matthew B. Stone, R. Salci, D. A. Acar, F. O. Oztirpan, Şener Ozonder, Andreas Kreyssig, Alan I. Goldman, David C. Johnston, Robert J. Mcqueeney Oct 2019

Heisenberg Model Analysis On Inelastic Powder Neutron Scattering Data Using Parent And K Doped Bamn2as2 Samples, Mehmet Ramazanoglu, Aashish Sapkota, Abhishek Pandey, Jagat Lamsal, Douglas L. Abernathy, Jennifer L. Niedziela, Matthew B. Stone, R. Salci, D. A. Acar, F. O. Oztirpan, Şener Ozonder, Andreas Kreyssig, Alan I. Goldman, David C. Johnston, Robert J. Mcqueeney

A. I. Goldman

Low temperature powder inelastic neutron scattering measurements were performed on three different powder samples; parent BaMn2As2,12.5% K-doped Ba0.875K0.125Mn2As2 and 25% K-doped Ba(0.75)K0.25Mn2As2. The Heisenberg Model involving J1‐J2‐Jz coupling constants were compared to the data by a powder integration routine using Monte Carlo integration methods. The best magnetic parameters were selected using a chi-square test where model intensities were compared to the full (q,E) dependence of magnetic scattering. A key step to this analysis is the characterization of the background which is formed mostly by phonon scattering intensities along with ...


Antiferromagnetic Stacking Of Ferromagnetic Layers And Doping-Controlled Phase Competition In Ca1−X Srx Co2−Y As2, Bing Li, Yuriy Sizyuk, Nediadath S. Sangeetha, John M. Wilde, Pinaki Das, W. Tian, David C. Johnston, Alan I. Goldman, Andreas Kreyssig, Peter P. Orth, Robert J. Mcqueeney, Benjamin G. Ueland Oct 2019

Antiferromagnetic Stacking Of Ferromagnetic Layers And Doping-Controlled Phase Competition In Ca1−X Srx Co2−Y As2, Bing Li, Yuriy Sizyuk, Nediadath S. Sangeetha, John M. Wilde, Pinaki Das, W. Tian, David C. Johnston, Alan I. Goldman, Andreas Kreyssig, Peter P. Orth, Robert J. Mcqueeney, Benjamin G. Ueland

A. I. Goldman

In search of a quantum phase transition between the two-dimensional (2D) ferromagnetism of CaCo2−yAs2 and stripe-type antiferromagnetism in SrCo2 As2, we instead find evidence for 1D magnetic frustration between magnetic square Co layers. We present neutron-diffraction data for Ca1−x Srx Co2−y As2 that reveal a sequence of x -dependent magnetic transitions which involve different stacking of 2 D ferromagnetically aligned layers with different magnetic anisotropy. We explain the x-dependent changes to the magnetic order by utilizing classical analytical calculations of a 1D Heisenberg model where single-ion magnetic anisotropy and frustration of antiferromagnetic nearest- and next-nearest-layer exchange interactions ...


Crystal Growth, Microstructure, And Physical Properties Of Srmnsb2, Yong Liu, Tao Ma, Warren E. Straszheim, Farhan Islam, Brandt A. Jensen, Wei Tian, Thomas Heitmann, R. A. Rosenberg, John M. Wilde, Bing Li, Andreas Kreyssig, Alan I. Goldman, Benjamin G. Ueland, Robert J. Mcqueeney, David Vaknin Oct 2019

Crystal Growth, Microstructure, And Physical Properties Of Srmnsb2, Yong Liu, Tao Ma, Warren E. Straszheim, Farhan Islam, Brandt A. Jensen, Wei Tian, Thomas Heitmann, R. A. Rosenberg, John M. Wilde, Bing Li, Andreas Kreyssig, Alan I. Goldman, Benjamin G. Ueland, Robert J. Mcqueeney, David Vaknin

A. I. Goldman

We report on the crystal and magnetic structures and magnetic and transport properties of SrMnSb2 single crystals grown by the self-flux method. Magnetic susceptibility measurements reveal an antiferromagnetic (AFM) transition at TN=295(3) K. Above TN, the susceptibility slightly increases and forms a broad peak at T∼420 K, which is a typical feature of two-dimensional magnetic systems. Neutron diffraction measurements on single crystals confirm the previously reported C-type AFM structure below TN. Both de Haas-van Alphen (dHvA) and Shubnikov-de Haas (SdH) effects are observed in SrMnSb2 single crystals. Analysis of the oscillatory component by a Fourier transform shows ...


Competing Magnetic Phases And Itinerant Magnetic Frustration In Srco2 As2, Bing Li, Benjamin G. Ueland, W. T. Jayasekara, D. L. Abernathy, N. S. Sangeetha, David C. Johnston, Qing-Ping Ding, Yuji Furukawa, Peter P. Orth, Andreas Kreyssig, Alan I. Goldman, Robert J. Mcqueeney Oct 2019

Competing Magnetic Phases And Itinerant Magnetic Frustration In Srco2 As2, Bing Li, Benjamin G. Ueland, W. T. Jayasekara, D. L. Abernathy, N. S. Sangeetha, David C. Johnston, Qing-Ping Ding, Yuji Furukawa, Peter P. Orth, Andreas Kreyssig, Alan I. Goldman, Robert J. Mcqueeney

A. I. Goldman

Whereas magnetic frustration is typically associated with local-moment magnets in special geometric arrangements, here we show that SrCo2As2 is a candidate for frustrated itinerant magnetism. Using inelastic neutron scattering (INS), we find that antiferromagnetic (AF) spin fluctuations develop in the square Co layers of SrCo2As2 below T approximate to 100 K centered at the stripe-type AF propagation vector of (1/2, 1/2), and that their development is concomitant with a suppression of the uniform magnetic susceptibility determined via magnetization measurements. We interpret this switch in spectral weight as signaling a temperature-induced crossover from an instability toward ferromagnetism ordering to ...


Competing Magnetic Phases And Itinerant Magnetic Frustration In Srco2 As2, Bing Li, Benjamin G. Ueland, W. T. Jayasekara, D. L. Abernathy, N. S. Sangeetha, David C. Johnston, Qing-Ping Ding, Yuji Furukawa, Peter P. Orth, Andreas Kreyssig, Alan I. Goldman, Robert J. Mcqueeney Oct 2019

Competing Magnetic Phases And Itinerant Magnetic Frustration In Srco2 As2, Bing Li, Benjamin G. Ueland, W. T. Jayasekara, D. L. Abernathy, N. S. Sangeetha, David C. Johnston, Qing-Ping Ding, Yuji Furukawa, Peter P. Orth, Andreas Kreyssig, Alan I. Goldman, Robert J. Mcqueeney

Peter P. Orth

Whereas magnetic frustration is typically associated with local-moment magnets in special geometric arrangements, here we show that SrCo2As2 is a candidate for frustrated itinerant magnetism. Using inelastic neutron scattering (INS), we find that antiferromagnetic (AF) spin fluctuations develop in the square Co layers of SrCo2As2 below T approximate to 100 K centered at the stripe-type AF propagation vector of (1/2, 1/2), and that their development is concomitant with a suppression of the uniform magnetic susceptibility determined via magnetization measurements. We interpret this switch in spectral weight as signaling a temperature-induced crossover from an instability toward ferromagnetism ordering to ...


Skyrmions And Spirals In Mnsi Under Hydrostatic Pressure, L. J. Bannenberg, R. Sadykov, R. M. Dalgliesh, C. Goodway, Deborah L. Schlagel, Thomas A. Lograsso, P. Falus, E. Lelièvre-Berna, A. O. Leonov, C. Pappas Oct 2019

Skyrmions And Spirals In Mnsi Under Hydrostatic Pressure, L. J. Bannenberg, R. Sadykov, R. M. Dalgliesh, C. Goodway, Deborah L. Schlagel, Thomas A. Lograsso, P. Falus, E. Lelièvre-Berna, A. O. Leonov, C. Pappas

Thomas A. Lograsso

The archetype cubic chiral magnet MnSi is home to some of the most fascinating states in condensed matter, such as skyrmions and a non-Fermi-liquid behavior in conjunction with a topological Hall effect under hydrostatic pressure. Using small angle neutron scattering, we study the evolution of the helimagnetic, conical, and skyrmionic correlations with increasing hydrostatic pressure. We show that the helical propagation vector smoothly reorients from ⟨111⟩ to ⟨100⟩ at intermediate pressures. At higher pressures, above the critical pressure, the long-range helimagnetic order disappears at zero magnetic field. Nevertheless, skyrmion lattices and conical spirals form under magnetic fields, in a part ...


Skyrmions And Spirals In Mnsi Under Hydrostatic Pressure, L. J. Bannenberg, R. Sadykov, R. M. Dalgliesh, C. Goodway, Deborah L. Schlagel, Thomas A. Lograsso, P. Falus, E. Lelièvre-Berna, A. O. Leonov, C. Pappas Oct 2019

Skyrmions And Spirals In Mnsi Under Hydrostatic Pressure, L. J. Bannenberg, R. Sadykov, R. M. Dalgliesh, C. Goodway, Deborah L. Schlagel, Thomas A. Lograsso, P. Falus, E. Lelièvre-Berna, A. O. Leonov, C. Pappas

Deborah L. Schlagel

The archetype cubic chiral magnet MnSi is home to some of the most fascinating states in condensed matter, such as skyrmions and a non-Fermi-liquid behavior in conjunction with a topological Hall effect under hydrostatic pressure. Using small angle neutron scattering, we study the evolution of the helimagnetic, conical, and skyrmionic correlations with increasing hydrostatic pressure. We show that the helical propagation vector smoothly reorients from ⟨111⟩ to ⟨100⟩ at intermediate pressures. At higher pressures, above the critical pressure, the long-range helimagnetic order disappears at zero magnetic field. Nevertheless, skyrmion lattices and conical spirals form under magnetic fields, in a part ...


Distinct Pressure Evolution Of Coupled Nematic And Magnetic Orders In Fese, Anna E. Böhmer, Karunakar Kothapalli, Wageesha T. Jayasekara, John M. Wilde, Bing Li, Aashish Sapkota, Benjamin G. Ueland, Pinaki Das, Yumin Xiao, Wenli Bi, Jiyong Zhao, E. Ercan Alp, Sergey L. Bud’Ko, Paul C. Canfield, Alan I. Goldman, Andreas Kreyssig Oct 2019

Distinct Pressure Evolution Of Coupled Nematic And Magnetic Orders In Fese, Anna E. Böhmer, Karunakar Kothapalli, Wageesha T. Jayasekara, John M. Wilde, Bing Li, Aashish Sapkota, Benjamin G. Ueland, Pinaki Das, Yumin Xiao, Wenli Bi, Jiyong Zhao, E. Ercan Alp, Sergey L. Bud’Ko, Paul C. Canfield, Alan I. Goldman, Andreas Kreyssig

Paul C. Canfield

We present a microscopic study of nematicity and magnetism in FeSe over a wide temperature and pressure range using high-energy x-ray diffraction and time-domain Mössbauer spectroscopy. The low-temperature magnetic hyperfine field increases monotonically up to ∼ 6 GPa. The orthorhombic distortion initially decreases under increasing pressure but is stabilized at intermediate pressures by cooperative coupling to the pressure-induced magnetic order. Close to the reported maximum of the superconducting critical temperature at p = 6.8 GPa , the orthorhombic distortion suddenly disappears and a new tetragonal magnetic phase occurs. The pressure and temperature evolution of the structural and magnetic order parameters suggests that ...


Multiple Ferromagnetic Transitions And Structural Distortion In The Van Der Waals Ferromagnet Vi3 At Ambient And Finite Pressures, Elena Gati, Yuji Inagaki, Tai Kong, Robert J. Cava, Yuji Furukawa, Paul C. Canfield, Sergey L. Bud’Ko Oct 2019

Multiple Ferromagnetic Transitions And Structural Distortion In The Van Der Waals Ferromagnet Vi3 At Ambient And Finite Pressures, Elena Gati, Yuji Inagaki, Tai Kong, Robert J. Cava, Yuji Furukawa, Paul C. Canfield, Sergey L. Bud’Ko

Paul C. Canfield

We present a combined study of zero-field (51) V and I-127 NMR at ambient pressure and specific heat and magnetization measurements under pressure up to 2.08 GPa on bulk single crystals of the van der Waals ferromagnet VI3. At ambient pressure, our results consistently demonstrate that VI3 undergoes a structural transition at T-s approximate to 78 K, followed by two subsequent ferromagnetic transitions at T-FM1 approximate to 50 K and T-FM2 approximate to 36 K upon cooling. At lowest temperature (T < T-FM2), two magnetically ordered V sites exist, whereas only one magnetically ordered V site is observed for T-FM1 < T < T-FM2. Whereas T-FM1 is almost unaffected by external pressure, T-FM2 is highly responsive to pressure and merges with the T-FM1 line at p 0.6 GPa. At even higher pressures (p approximate to 1.25 GPa), the T-FM2 line merges with the structural transition at T-s which becomes moderately suppressed with p for p < 1.25 GPa. Taken together, our data point toward a complex magnetic structure and an interesting interplay of magnetic and structural degrees of freedom in VI3.


Effect Of Ni Doping On Vortex Pinning In Cak (Fe1−X Nix)4as4 Single Crystals, N. Haberkorn, Mingyu Xu, William R. Meier, J. Schmidt, Sergey L. Bud’Ko, Paul C. Canfield Oct 2019

Effect Of Ni Doping On Vortex Pinning In Cak (Fe1−X Nix)4as4 Single Crystals, N. Haberkorn, Mingyu Xu, William R. Meier, J. Schmidt, Sergey L. Bud’Ko, Paul C. Canfield

Paul C. Canfield

We study the correlation between chemical composition and vortex dynamics in Ni-doped CaK(Fe1−xNix)4As4 (x=0, 0.015, 0.025, 0.03, and 0.05) single crystals by performing measurements of the critical current densities Jc and the flux creep rates S. The magnetic relaxation of all the crystals is well described by the collective creep theory. The samples display a glassy exponent μ within the predictions for vortex bundles in a weak pinning scenario and relatively small characteristic pinning energy (U0<100K). The undoped crystals display modest Jc values at low temperatures and high magnetic fields applied along the c axis. Jc(T) dependences at high fields display an unusual peak. The enhancement in Jc(T) matches with an increase in U0 and the appearance of a second peak in the magnetization. As Ni doping increases, whereas there is a monotonic decrease in Tc there is a nonmonotonic change in Jc. Initially Jc increases, reaching a maximum value for x=0.015, and then Jc decreases for x≥0.025. This change in Jc(x) is coincident with the onset of antiferromagnetic order. The magnetic field dependence of Jc(H) also manifests a change in behavior between these x values. The analysis of the vortex dynamics for small and intermediate magnetic fields shows a gradual evolution in the glassy exponent μ with Ni content, x. This implies that there is no appreciable change in the mechanism that determines the vortex relaxation.


An Effective Electric Dipole Model For Voltage-Induced Gating Mechanism Of Lysenin, Eric Krueger, Daniel Fologea Oct 2019

An Effective Electric Dipole Model For Voltage-Induced Gating Mechanism Of Lysenin, Eric Krueger, Daniel Fologea

Daniel Fologea

Lysenin is a pore-forming toxin, which self-inserts open channels into sphingomyelin containing membranes and is known to be voltage regulated. The mechanistic details of its voltage gating mechanism, however, remains elusive despite much recent efforts. Here, we have employed a novel combination of experimental and computational techniques to examine a model for voltage gating, that is based on the existence of an “effective electric dipole” inspired by recent reported structures of lysenin. We support this mechanism by the observations that (i) the charge-reversal and neutralization substitutions in lysenin result in changing its electrical gating properties by modifying the strength of ...


Thermo-Mechanical Response Of Self-Assembled Nanoparticle Membranes, Yifan Wang, Henry Chan, Badri Narayanan, Sean P. Mcbride, Subramanian K.R.S. Sankaranarayanan, Xiao-Min Lin, Heinrich M. Jaeger Sep 2019

Thermo-Mechanical Response Of Self-Assembled Nanoparticle Membranes, Yifan Wang, Henry Chan, Badri Narayanan, Sean P. Mcbride, Subramanian K.R.S. Sankaranarayanan, Xiao-Min Lin, Heinrich M. Jaeger

Dr. Sean P. McBride

Ultrathin membranes composed of metallic or semiconducting nanoparticles capped with short ligand molecules are hybrid materials that have attracted considerable research interest.1-12 In contrast to two-dimensional (2D) membranes such as graphene and transition metal dichalcogenides monolayers, nanoparticle membranes can be engineered to achieve widely tunable mechanical, electronic or optical properties through different combinations of inorganic cores and organic ligands. In terms of mechanical properties, these membranes can form large area (tens of microns in diameter) freestanding structures with high Young’s moduli (~GPa) and fracture strength.1,13-15 Molecular dynamics (MD) simulations have indicated how this mechanical robustness can ...


Transmission And Guiding Of Fast Electrons Through Insulating Nanocapillaries And Comparison With Ion Guiding, Susanta Das Sep 2019

Transmission And Guiding Of Fast Electrons Through Insulating Nanocapillaries And Comparison With Ion Guiding, Susanta Das

Susanta Das

Transmission and guiding of fast electrons (500 and 1000 eV) through an insulating polyethylene terephthalate nanocapillary foil has been investigated and compared with results for slow highly charged ions. As for slow ions, guiding is attributed to charge-up of the inner walls near the capillary entrance, which, after a characteristic time, electrostatically deflects the traversing ions causing them to be guided through the sample along the capillary axis. The measurements were performed at WMU. Electron guiding is found to decrease faster with both energy and foil tilt angle than for ions. Ions lose negligible energy during the course of guiding ...


Modeling Energy Dynamics With The Energy-Interaction Diagram, Benedikt W. Harrer, Cassandra A. Paul Sep 2019

Modeling Energy Dynamics With The Energy-Interaction Diagram, Benedikt W. Harrer, Cassandra A. Paul

Benedikt W. Harrer

Energy is an important crosscutting concept in all science disciplines, and energy conservation is widely regarded as one of the most important principles in physics.1–3 Over the years, numerous graphical representations have been proposed that allow learners of physics to visualize energy states and dynamics in a particular situation.3–7 Each diagram highlights different aspects of energy and therefore may represent different conceptualizations of energy. Bar charts,8 for example, foreground the idea of multiple categories of energy to account for the distribution of energy in a system across those energy types. Similarly, pie charts5 highlight ...


Enhancing Cellular Uptake Of Magnetic Nanoparticles For Cancer Therapy Via Nanoparticle Engineering & Sonoporation, Ronald Kumon, Prem Vaishnava, Ronald Tackett, Lihua Wang, Cheryl Samaniego, Alexis Siegel, Sally Dagher Sep 2019

Enhancing Cellular Uptake Of Magnetic Nanoparticles For Cancer Therapy Via Nanoparticle Engineering & Sonoporation, Ronald Kumon, Prem Vaishnava, Ronald Tackett, Lihua Wang, Cheryl Samaniego, Alexis Siegel, Sally Dagher

Cheryl Samaniego

Magnetic induction heating of iron oxide nanoparticles has been proposed as a method for noninvasive cancer treatment without the side effects of chemotherapy and ionizing radiation. At Kettering University we propose to improve the uptake of nanoparticles by cells through the use of nanoparticle engineering and ultrasonic fields.


Uncompensated Polarization In Incommensurate Modulations Of Perovskite Antiferroelectrics, Tao Ma, Zhongming Fan, Bin Xu, Tae-Hoon Kim, Ping Lu, Laurent Bellaiche, Matthew J. Kramer, Xiaoli Tan, Lin Zhou Sep 2019

Uncompensated Polarization In Incommensurate Modulations Of Perovskite Antiferroelectrics, Tao Ma, Zhongming Fan, Bin Xu, Tae-Hoon Kim, Ping Lu, Laurent Bellaiche, Matthew J. Kramer, Xiaoli Tan, Lin Zhou

Xiaoli Tan

Complex polar structures of incommensurate modulations (ICMs) are revealed in chemically modified PbZrO3 perovskite antiferroelectrics using advanced transmission electron microscopy techniques. The Pb-cation displacements, previously assumed to arrange in a fully-compensated antiparallel fashion, are found to be either antiparallel but with different magnitudes, or in a nearly orthogonal arrangement in adjacent stripes in the ICMs. Ab initio calculations corroborate the low-energy state of these arrangements. Our discovery corrects the atomic understanding of ICMs in PbZrO3-based perovskite antiferroelectrics.


Spatial And Orientational Control Of Liquid Crystal Alignment Using A Surface Localized Polymer Layer, Lu Lu, Tatiana Sergan, Vassili Sergan, Philip J. Bos Sep 2019

Spatial And Orientational Control Of Liquid Crystal Alignment Using A Surface Localized Polymer Layer, Lu Lu, Tatiana Sergan, Vassili Sergan, Philip J. Bos

Lu Lu

We present an alignment method for the surface contacting liquid crystal (LC) director. This method allows complete control of the polar pretilt angle as a function of position in a liquid crystal device, and has the potential of controlling the azimuthal orientation of LC. Important considerations of this method are to form a thin layer of reactive monomers at the LC cell interior surface, and to control the deleterious effects of flow due to polymerization induced concentration gradients. To achieve these, the voltage and frequency of the applied electric field and the UV intensity during the polymerization process are significant.


Mechanism Of Electric-Field-Induced Segregation Of Additives In A Liquid-Crystal Host, Lu Lu, Vassili Sergan, Philip J. Bos Sep 2019

Mechanism Of Electric-Field-Induced Segregation Of Additives In A Liquid-Crystal Host, Lu Lu, Vassili Sergan, Philip J. Bos

Lu Lu

The mechanism for electric-field-induced segregation of additives, containing a polar group, in a host liquid crystal is proposed. It is shown that the polarity of an applied dc electric field, or the frequency of an ac electric field, strongly influences the segregation of reactive monomers containing an ester group. An explanation of this result is offered based on the association of dissolved ions with polar groups of the reactive monomers. This association is considered to cause these types of additives to drift to the cell surface in the presence of an external electric field. The described mechanism can be applied ...


Mechanisms Of Methane Transport Through Populus Trichocarpa, Ellynne Marie Kutschera, M. A. K. Khalil, Andrew Rice, Todd Rosenstiel Sep 2019

Mechanisms Of Methane Transport Through Populus Trichocarpa, Ellynne Marie Kutschera, M. A. K. Khalil, Andrew Rice, Todd Rosenstiel

Todd N. Rosenstiel

Although the dynamics of methane (CH4) emission from croplands and wetlands have been fairly well investigated, the contribution of trees to global CH4 emission and the mechanisms of tree transport are relatively unknown. CH4 emissions from the common wetland tree species Populus trichocarpa (black cottonwood) native to the Pacific Northwest were measured under hydroponic conditions in order to separate plant transport mechanisms from the influence of soil processes. Roots were exposed to CH4 enriched water and canopy emissions of CH4 were measured. The average flux for 34 trials (at temperatures ranging from 17 to 25 °C) was 2.8 ± 2 ...


Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015-2017 Ligo Data, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia Sep 2019

Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015-2017 Ligo Data, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia

Marco Cavaglia

We present a search for gravitational waves from 222 pulsars with rotation frequencies ≳ 10 Hz. We use advanced LIGO data from its first and second observing runs spanning 2015-2017, which provides the highest-sensitivity gravitational-wave data so far obtained. In this search we target emission from both the l = m = 2 mass quadrupole mode, with a frequency at twice that of the pulsar's rotation, and the l = 2, m = 1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l = m = 2 mode search ...


Waccmxdata, Xuguang Cai Aug 2019

Waccmxdata, Xuguang Cai

Xuguang Cai

This is the waccmx-dart data that I used for my chile paper. It is the Temperature, zonal, meridional and vertical winds, altitude from 90 to 452 km, altitude resolution 2 km and temporal resolution 1-hour. The data is April 23, 2015


Treating Epilepsy With Physics, Louis R. Nemzer Aug 2019

Treating Epilepsy With Physics, Louis R. Nemzer

Louis R Nemzer

No abstract provided.


Ucna/Ucna+, Robert Pattie Aug 2019

Ucna/Ucna+, Robert Pattie

Robert W. Pattie Jr.

The neutron provides a simple yet dynamic nuclear system to study the Standard Model of Particle Physics. The process of transforming a neutron into a proton, an electron, and an anti-neutrino contains a wealth of information in the decay rate and the kinematics of the emitted particles. Precision measurements of angular correlations in neutron β-decay can lend insight to the structure of the weak interaction and probe for physics beyond the Standard Model. The UCNA experiment at the Los Alamos Neutron Science Center is the only experiment to use ultracold neutrons to perform such a measurement, determining the β-asymmetry parameter ...


Fatigue-Resistant High-Performance Elastocaloric Materials Via Additive Manufacturing, Huilong Hou, Emrah Simsek, Tao Ma, Nathan S. Johnson, Suxin Qian, Cheikh Cissé, Drew Stasak, Naila Al Hasan, Lin Zhou, Yunho Hwang, Reinhard Radermacher, Valery I. Levitas, Matthew J. Kramer, Mohsen Asle Zaeem, Aaron P. Stebner, Ryan T. Ott, Jun Cui, Ichiro Takeuchi Aug 2019

Fatigue-Resistant High-Performance Elastocaloric Materials Via Additive Manufacturing, Huilong Hou, Emrah Simsek, Tao Ma, Nathan S. Johnson, Suxin Qian, Cheikh Cissé, Drew Stasak, Naila Al Hasan, Lin Zhou, Yunho Hwang, Reinhard Radermacher, Valery I. Levitas, Matthew J. Kramer, Mohsen Asle Zaeem, Aaron P. Stebner, Ryan T. Ott, Jun Cui, Ichiro Takeuchi

Valery I. Levitas

Elastocaloric cooling, which exploits the latent heat released and absorbed as stress-induced phase transformations are reversibly cycled in shape memory alloys, has recently emerged as a frontrunner in non-vapor-compression cooling technologies. The intrinsically high thermodynamic efficiency of elastocaloric materials is limited only by work hysteresis. Here, we report on creating high-performance low-hysteresis elastocaloric cooling materials via additive manufacturing of Titanium-Nickel (Ti-Ni) alloys. Contrary to established knowledge of the physical metallurgy of Ti-Ni alloys, intermetallic phases are found to be beneficial to elastocaloric performances when they are combined with the binary Ti-Ni compound in nanocomposite configurations. The resulting microstructure gives rise ...