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Articles 1 - 13 of 13
Full-Text Articles in Physics
A Model For The Hysteresis Observed In Gating Of Lysenin Channels, Eric Krueger, Radwan Al Faouri, Daniel Fologea, Ralph Henry, David Straub, Greg J. Salamo
A Model For The Hysteresis Observed In Gating Of Lysenin Channels, Eric Krueger, Radwan Al Faouri, Daniel Fologea, Ralph Henry, David Straub, Greg J. Salamo
Physics Faculty Publications and Presentations
The pore-forming toxin lysenin self-inserts to form conductance channels in natural and artificial lipid membranes containing sphingomyelin. The inserted channels exhibit voltage regulation and hysteresis of the macroscopic current during the application of positive periodic voltage stimuli. We explored the bi-stable behavior of lysenin channels and present a theoretical approach for the mechanism of the hysteresis to explain its static and dynamic components. This investigation develops a model to incorporate the role of charge accumulation on the bilayer lipid membrane in influencing the channel conduction state. Our model is supported by experimental results and also provides insight into the temperature …
Adsorption-Controlled Growth Of Bivo4 By Molecular-Beam Epitaxy, D. A. Hillsberry, D. A. Tenne
Adsorption-Controlled Growth Of Bivo4 By Molecular-Beam Epitaxy, D. A. Hillsberry, D. A. Tenne
Physics Faculty Publications and Presentations
Single-phase epitaxial films of the monoclinic polymorph of BiVO4 were synthesized by reactive molecular-beam epitaxy under adsorption-controlled conditions. The BiVO4 films were grown on (001) yttria-stabilized cubic zirconia (YSZ) substrates. Four-circle x-ray diffraction, scanning transmission electron microscopy (STEM), and Raman spectroscopy confirm the epitaxial growth of monoclinic BiVO4 with an atomically abrupt interface and orientation relationship (001)BiVO4 ∥ (001)YSZ with [100]BiVO4 ∥ [100]YSZ. Spectroscopic ellipsometry, STEM electron energy loss spectroscopy (STEM-EELS), and x-ray absorption spectroscopy indicate that the films have a direct band gap of 2.5 ± 0.1 eV.
Fluctuant Magnetism In Metal Oxide Nanocrystals Capped With Surfactants, Aaron Thurber, Michael S. Jones, Dmitri Tenne, Charles B. Hanna, Alex Punnoose
Fluctuant Magnetism In Metal Oxide Nanocrystals Capped With Surfactants, Aaron Thurber, Michael S. Jones, Dmitri Tenne, Charles B. Hanna, Alex Punnoose
Physics Faculty Publications and Presentations
We demonstrate experimentally that magnetism in ZnO, TiO2, CeO2, andSnO2 nanocrystals (NCs) has a fluctuant nature that varies with capping surfactant type and concentration. By developing a forced hydrolysis approach with additional postprocessing for the synthesis and surfactant capping of these NCs, we effectively avoid the influence of size, shape, and magnetic impurities on the magnetic behavior of NCs, thus revealing the systematic influence of the capping surfactants on the NC magnetism. The x-ray photoelectron spectroscopy results and theoretical calculations clearly show that the magnetism fluctuation with surfactant concentration can be attributed to the periodic …
Optimization Of Force Sensitivity In Q-Controlled Amplitude-Modulation Atomic Force Microscopy, Jongwoo Kim, Baekman Sung, Byung I. Kim, Wonho Jhe
Optimization Of Force Sensitivity In Q-Controlled Amplitude-Modulation Atomic Force Microscopy, Jongwoo Kim, Baekman Sung, Byung I. Kim, Wonho Jhe
Physics Faculty Publications and Presentations
We present control of force sensitivity in Q-controlled amplitude-modulation atomic force microscopy (AM-AFM) that is based on the high-Q quartz tuning-fork. It is found that the phase noise is identical to the amplitude noise divided by oscillation amplitude in AM-AFM. In particular, we observe that while Q-control does not compromise the signal-to-noise ratio, it enhances the detection sensitivity because the minimum detectable force gradient is inversely proportional to the effective quality factor for large bandwidths, which is due to reduction of frequency noise. This work demonstrates Q-control in AM-AFM is a useful technique for enhancement of …
Direct Observation Of Self-Assembled Chain-Like Water Structures In A Nanoscopic Water Meniscus, Byung I. Kim, Ryan D. Boehm, Jeremy R. Bonander
Direct Observation Of Self-Assembled Chain-Like Water Structures In A Nanoscopic Water Meniscus, Byung I. Kim, Ryan D. Boehm, Jeremy R. Bonander
Physics Faculty Publications and Presentations
Sawtooth-like oscillatory forces generated by water molecules confined between two oxidized silicon surfaces were observed using a cantilever-based optical interfacial force microscope when the two surfaces approached each other in ambient environments. The humidity-dependent oscillatory amplitude and periodicity were 3-12 nN and 3-4 water diameters, respectively. Half of each period was matched with a freely jointed chain model, possibly suggesting that the confined water behaved like a bundle of water chains. The analysis also indicated that water molecules self-assembled to form chain-like structures in a nanoscopic meniscus between two hydrophilic surfaces in air. From the friction force data measured simultaneously, …
Influence Of Microstructure On The Propagation Of Fatigue Cracks In Inconel 617, Benjiman Michael Albiston
Influence Of Microstructure On The Propagation Of Fatigue Cracks In Inconel 617, Benjiman Michael Albiston
Boise State University Theses and Dissertations
Inconel 617 is a candidate material for use in the intermediate heat exchanger of the Next Generation Nuclear Plant. Because of the high temperatures and the fluctuations in stress and temperature, the fatigue behavior of the material is important to understand. The goal of this study was to determine the influences of the microstructure during fatigue crack propagation. For this investigation, Inconel 617 compact tension samples, fatigue tested by Julian Benz at the Idaho National Laboratory, were obtained. The testing conditions included two environments at 650 °C (lab air and impure-He) and varied testing parameters including: loading waveform (triangular, trapezoidal), …
Role Of Oxygen Defects On The Magnetic Properties Of Ultra-Small Sn1−XFeXO2 Nanoparticles, Kelsey Dodge, Jordan Chess, Josh Eixenberger, Gordon Alanko, Charles B. Hanna, Alex Punnoose
Role Of Oxygen Defects On The Magnetic Properties Of Ultra-Small Sn1−XFeXO2 Nanoparticles, Kelsey Dodge, Jordan Chess, Josh Eixenberger, Gordon Alanko, Charles B. Hanna, Alex Punnoose
Physics Faculty Publications and Presentations
Although the role of oxygen defects in the magnetism of metal oxide semiconductors has been widely discussed, it is been difficult to directly measure the oxygen defect concentration of samples to verify this. This work demonstrates a direct correlation between the photocatalytic activity of Sn1−xFexO2 nanoparticles and their magnetic properties. For this, a series of ~2.6 nm sized, well characterized, single-phase Sn1−xFexO2 crystallites with x = 0−0.20 were synthesized using tin acetate, urea, and appropriate amounts of iron acetate. X-ray photoelectron spectroscopy confirmed the concentration and 3+ oxidation state of …
Magnetic Properties Of Fe Doped, Co Doped, And Fe+Co Co-Doped Zno, J. J. Beltrán, J. A. Osorio, C. A. Barrero, Charles B. Hanna, A. Punnoose
Magnetic Properties Of Fe Doped, Co Doped, And Fe+Co Co-Doped Zno, J. J. Beltrán, J. A. Osorio, C. A. Barrero, Charles B. Hanna, A. Punnoose
Physics Faculty Publications and Presentations
The structural, electronic, and magnetic properties of Zn0.95Co0.05O, Zn0.95Fe0.05O, and Zn0.90Fe0.05Co0.05O nanoparticles prepared by a sol-gel method are presented and discussed. X-ray diffraction and optical analysis indicated that high spin Co2+ ions substitute for the Zn2+ ions in tetrahedral sites. 57Fe Mössbauer spectroscopy showed the presence of isolated paramagnetic Fe3+ ions in both Fe doped and Fe+Co co-doped ZnO, however, no evidence of ferromagnetically ordered Fe3+ ions is observed. In the Zn0.95Fe0.05O sample, weak presence of ZnFe …
Cantilever-Based Optical Interfacial Force Microscope In Liquid Using An Optical-Fiber Tip, Byung I. Kim, Luke Smith, Thanh Tran, Steven Rossland, Erik Parkinson
Cantilever-Based Optical Interfacial Force Microscope In Liquid Using An Optical-Fiber Tip, Byung I. Kim, Luke Smith, Thanh Tran, Steven Rossland, Erik Parkinson
Physics Faculty Publications and Presentations
We developed a novel cantilever-based optical interfacial force microscope (COIFM) to study molecular interaction in liquid environments. The force sensor was created by attaching a chemically etched optical-fiber tip to the force sensor with UV epoxy, and characterized by imaging on a calibration grid. The performance of the COIFM was then demonstrated by measuring the force between two oxidized silicon surfaces in 1 mM KCl as a function of distance. The result was consistent with previously reported electrical double layer forces, suggesting that a COIFM using an optical-fiber tip is capable of measuring force in a liquid environment.
Imaging Stability In Force-Feedback High-Speed Atomic Force Microscopy, Byung I. Kim, Ryan Boehm
Imaging Stability In Force-Feedback High-Speed Atomic Force Microscopy, Byung I. Kim, Ryan Boehm
Physics Faculty Publications and Presentations
We studied the stability of force-feedback high-speed atomic force microscopy (HSAFM) by imaging soft, hard, and biological sample surfaces at various applied forces. The HSAFM images showed sudden topographic variations of streaky fringes with a negative applied force when collected on a soft hydrocarbon film grown on a grating sample, whereas they showed stable topographic features with positive applied forces. The instability of HSAFM images with the negative applied force was explained by the transition between contact and noncontact regimes in the force-distance curve. When the grating surface was cleaned, and thus hydrophilic by removing the hydrocarbon film, enhanced imaging …
Effects Of Gaas(Sb) Cladding Layers On Inas/Alassb Quantum Dots, Paul J. Simmonds
Effects Of Gaas(Sb) Cladding Layers On Inas/Alassb Quantum Dots, Paul J. Simmonds
Paul J. Simmonds
The structural and optical properties of InAs self-assembled quantum dots buried in AlAs0.56Sb0.44 barriers can be controlled using GaAs1−xSbx cladding layers. These cladding layers allow us to manage the amount of Sb immediately underneath and above the InAs quantum dots. The optimal cladding scheme has a GaAs layer beneath the InAs, and a GaAs0.95Sb0.05 layer above. This scheme results in improved dot morphology and significantly increased photoluminescence (PL) intensity. Both power-dependent and time-resolved photoluminescence confirm that the quantum dots have type-II band alignment. Enhanced carrier lifetimes in this quantum dot system …
A Gtc Study Of The Afterglow And Host Galaxy Of The Short-Duration Grb 100816a, J. P. Norris
A Gtc Study Of The Afterglow And Host Galaxy Of The Short-Duration Grb 100816a, J. P. Norris
Physics Faculty Publications and Presentations
We present the results from an optical monitoring campaign aimed at studying the afterglow properties of the short GRB 100816A. We implemented a new way of processing the Swift-BAT data, and based on it we reclassified this burst as short, discarding the initial classification as long. Observations were carried out mainly with the GTC Telescope within the four following days after the burst to investigate the optical photometry of its afterglow, and a year later to localize the host. We completed the optical imaging with the 1.23 m and 3.5 m CAHA Telescopes. We built and fitted the nIR-optical …
Cationic Polymers Inhibit The Conductance Of Lysenin Channels, Daniel Fologea, Eric Krueger, Steven Rossland, Sheenah Bryant, Wylie Foss
Cationic Polymers Inhibit The Conductance Of Lysenin Channels, Daniel Fologea, Eric Krueger, Steven Rossland, Sheenah Bryant, Wylie Foss
Physics Faculty Publications and Presentations
The pore-forming toxin lysenin self-assembles large and stable conductance channels in natural and artificial lipidmembranes.The lysenin channels exhibit unique regulation capabilities, which open unexplored possibilities to control the transport of ions and molecules through artificial and natural lipid membranes. Our investigations demonstrate that the positively charged polymers polyethyleneimine and chitosan inhibit the conducting properties of lysenin channels inserted into planar lipid membranes.The preservation of the inhibitory effect following addition of charged polymers on either side of the supporting membrane suggests the presence of multiple binding sites within the channel’s structure and a multistep inhibition mechanism that involves binding and trapping. …