Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 6 of 6
Full-Text Articles in Physics
Bi-Stability, Hysteresis, And Memory Of Voltage-Gated Lysenin Channels, Daniel Fologea, Eric Krueger, Yuriy I. Mazur, Christine Stith, Yui Okuyama, Ralph Henry, Greg J. Salamo
Bi-Stability, Hysteresis, And Memory Of Voltage-Gated Lysenin Channels, Daniel Fologea, Eric Krueger, Yuriy I. Mazur, Christine Stith, Yui Okuyama, Ralph Henry, Greg J. Salamo
Physics Faculty Publications and Presentations
Lysenin, a 297 amino acid pore-forming protein extracted from the coelomic fluid of the earthworm E. foetida, inserts constitutively open large conductance channels in natural and artificial lipid membranes containing sphingomyelin. The inserted channels show voltage regulation and slowly close at positive applied voltages. We report on the consequences of slow voltage-induced gating of lysenin channels inserted into a planar Bilayer Lipid Membrane (BLM), and demonstrate that these pore-forming proteins constitute memory elements that manifest gating bi-stability in response to variable external voltages. The hysteresis in macroscopic currents dynamically changes when the time scale of the voltage variation is …
A Large-Scale Synthesis And Characterization Of Quaternary CuinXGa1−XS2 Chalcopyrite Nanoparticles Via Microwave Batch Reactions, Chivin Sun, Richard D. Westover, Gary Long, Cyril Bajracharya, Jerry D. Harris, Alex Punnoose, Rene G. Rodriguez, Joshua J. Pak
A Large-Scale Synthesis And Characterization Of Quaternary CuinXGa1−XS2 Chalcopyrite Nanoparticles Via Microwave Batch Reactions, Chivin Sun, Richard D. Westover, Gary Long, Cyril Bajracharya, Jerry D. Harris, Alex Punnoose, Rene G. Rodriguez, Joshua J. Pak
Physics Faculty Publications and Presentations
Various quaternary CuInxGa1−xS2 (0 ≤ x ≤ 1) chalcopyrite nanoparticles have been prepared from molecular single-source precursors via microwave decomposition. We were able to control the nanoparticle size, phase, stoichiometry, and solubility. Depending on the choice of surface modifiers used, we were able to tune the solubility of the resulting nanoparticles. This method has been used to generate up to 5 g of nanoparticles and up to 150 g from multiple batch reactions with excellent reproducibility. Data from UV-Vis, photoluminescence, X-ray diffraction, TEM, DSC/TGA-MS, and ICP-OES analyses have shown high reproducibility in nanoparticle size, …
Spin And Exchange Coupling For Ti Embedded In A Surface Dipolar Network, Pushpa Raghani, Jesus Cruz, Barbara Jones
Spin And Exchange Coupling For Ti Embedded In A Surface Dipolar Network, Pushpa Raghani, Jesus Cruz, Barbara Jones
Physics Faculty Publications and Presentations
We have studied the spin and exchange coupling of Ti atoms deposited on a Cu2N/Cu(100) surface using density functional theory with generalized gradient approximation +U. In agreement with experiments, we find that Ti has the highest binding on top of Cu atoms. We also find that the spin of individual Ti atoms deposited on the Cu2N/Cu(100) surface increases as Ti coverage on the surface is decreased. For U=0, the spin of a Ti atom starts at S=0 at high coverages and increases to S=1/2 as the coverage is decreased, which agrees very well with results obtained from STM experiments. At …
Simultaneous Measurement Of Normal And Friction Forces Using A Cantilever-Based Optical Interfacial Force Microscope, Byung I. Kim, Jeremy R. Bonander, Jared A. Rasmussen
Simultaneous Measurement Of Normal And Friction Forces Using A Cantilever-Based Optical Interfacial Force Microscope, Byung I. Kim, Jeremy R. Bonander, Jared A. Rasmussen
Physics Faculty Publications and Presentations
We measured normal and friction forces simultaneously using a recently developed cantilever-based optical interfacial force microscope (COIFM) technique for studies of interfacial structures and mechanical properties of nanoscale materials. We derived how the forces can be incorporated into the detection signal using the classical Euler equation for beams. A lateral modulation with the amplitude of one nanometers was applied to create the friction forces between tip and sample. We demonstrated its capability by measuring normal and friction forces of interfacial water at the molecular scale over all distance ranges.
Magnetism Of Zno Nanoparticles: Dependence On Crystallite Size And Surfactant Coating, Aaron P. Thurber, Geoffrey L. Beausoleil Ii, Gordon A. Alanko, Joshua Anghel, Michael S. Jones, Lydia M. Johnson, Jianhui Zhang, Charles B. Hanna, Dmitri A. Tenne, Alex Punnoose
Magnetism Of Zno Nanoparticles: Dependence On Crystallite Size And Surfactant Coating, Aaron P. Thurber, Geoffrey L. Beausoleil Ii, Gordon A. Alanko, Joshua Anghel, Michael S. Jones, Lydia M. Johnson, Jianhui Zhang, Charles B. Hanna, Dmitri A. Tenne, Alex Punnoose
Physics Faculty Publications and Presentations
Many recent reports on magnetism in otherwise nonmagnetic oxides have demonstrated that nanoparticle size, surfactant coating, or doping with magnetic ions produces room-temperature ferromagnetism. Specifically, ZnO has been argued to be a room-temperature ferromagnet through all three of these methods in various experimental studies. For this reason, we have prepared a series of 1% Fe doped ZnO nanoparticle samples using a single forced hydrolysis co-precipitation synthesis method from the same precursors, while varying size (6 – 15 nm) and surface coating concentration to study the combined effects of these two parameters. Size was controlled by modifying the water concentration. Surfactant …
Unfortunate Outcomes Of A “Funny” Physics Problem: Some Eye-Opening Youtube Comments, Josip Slisko, Dewey I. Dykstra Jr.
Unfortunate Outcomes Of A “Funny” Physics Problem: Some Eye-Opening Youtube Comments, Josip Slisko, Dewey I. Dykstra Jr.
Physics Faculty Publications and Presentations
The impressions we make as instructors of physics can affect student learning and public perception of physics teachers, physics as an academic subject, and physics as a profession. There are many sources from which we can collect evidence of these impressions. Among these sources are online public forums such as those at the Internet site known as YouTube. Whether we are proud of these impressions we make or not, we should consider how constructive these impressions are for our students' physics learning and their impact on the public perception of physics and the community of physicists.