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Full-Text Articles in Physics

Carbide-Derived Carbon By Electrochemical Etching Of Vanadium Carbides, Luis G.B. Camargo, Benjamin G. Palazzo, Greg Taylor, Zach A. Norris, Yash K. Patel, Jeffrey D. Hettinger, Lei Yu Nov 2017

Carbide-Derived Carbon By Electrochemical Etching Of Vanadium Carbides, Luis G.B. Camargo, Benjamin G. Palazzo, Greg Taylor, Zach A. Norris, Yash K. Patel, Jeffrey D. Hettinger, Lei Yu

Jeffrey Hettinger

Carbide-derived Carbon (CDC) has been demonstrated to be an excellent electrode material for electrochemical devices including supercapacitors due to its chemical and electrochemical stability, large specific surface area and controllable pore size and morphology. Currently, CDC is prepared from metal carbides by chlorination in a chlorine gas atmosphere at temperatures of 350°C or higher. In this paper, conversion using electrochemical methods is reported, which can be achieved by oxidizing vanadium carbides (VC or V2C) in aqueous solutions at room temperature and a mild electrode potential to prepare CDC thin film as electrode materials for “on-chip” supercapacitiors. It was found ...


Superconductivity At Т≈200 K In Bismuth Cuprates Synthesized Using Solar Energy, J. G. Chigvinadze, Juana Vivó Acrivos, S. M. Ashimov, D. D. Gulamova, G. J. Donadze Oct 2017

Superconductivity At Т≈200 K In Bismuth Cuprates Synthesized Using Solar Energy, J. G. Chigvinadze, Juana Vivó Acrivos, S. M. Ashimov, D. D. Gulamova, G. J. Donadze

Juana Vivó Acrivos

When investigating low-frequency (0.1 Hz) oscillations of multiphase high-temperature cuprate superconductors (HTCS) Bi1,7Pb0,3Sr2Ca(n-1)CunOy (n=2-30), a wide attenuation peak (ΔT~100 К) with a maximum at Т≈200 К was detected. This peak was particularly pronounced in field cooling (FC) experiments, i.e. after abrupt cooling of the sample in the external magnetic field at the temperature Т<Тс with subsequent slow warming up to room temperature with invariance of the applied field. The attenuation peak height depended on the preliminary
orientation (before cooling) of the samples θ in the measured permanent magnetic field Н ...


A Coarse-Graining Approach For Molecular Simulation That Retains The Dynamics Of The All-Atom Reference System By Implementing Hydrodynamic Interactions, Sergiy Markutsya, Monica H. Lamm Oct 2017

A Coarse-Graining Approach For Molecular Simulation That Retains The Dynamics Of The All-Atom Reference System By Implementing Hydrodynamic Interactions, Sergiy Markutsya, Monica H. Lamm

Monica H. Lamm

We report on a new approach for deriving coarse-grained intermolecular forces that retains the frictional contribution that is often discarded by conventional coarse-graining methods. The approach is tested for water and an aqueous glucose solution, and the results from the new implementation for coarse-grained molecular dynamics simulation show remarkable agreement with the dynamics obtained from reference all-atom simulations. The agreement between the structural properties observed in the coarse-grained and all-atom simulations is also preserved. We discuss how this approach may be applied broadly to any existing coarse-graining method where the coarse-grained models are rigorously derived from all-atom reference systems.


Spin-Imbalance In A 2d Fermi-Hubbard System, Peter T. Brown, Debayan Mitra, Elmer Guardado-Sanchez, Peter Schauß, Stanimir S. Kondov, Ehsan Khatami, Thereza Paiva, Nandini Trivedi, David A. Huse, Waseem S. Bakr Sep 2017

Spin-Imbalance In A 2d Fermi-Hubbard System, Peter T. Brown, Debayan Mitra, Elmer Guardado-Sanchez, Peter Schauß, Stanimir S. Kondov, Ehsan Khatami, Thereza Paiva, Nandini Trivedi, David A. Huse, Waseem S. Bakr

Ehsan Khatami

The interplay of strong interactions and magnetic fields gives rise to unusual forms of superconductivity and magnetism in quantum many-body systems. Here, we present an experimental study of the two-dimensional Fermi-Hubbard model—a paradigm for strongly correlated fermions on a lattice—in the presence of a Zeeman field and varying doping. Using site-resolved measurements, we revealed anisotropic antiferromagnetic correlations, a precursor to long-range canted order. We observed nonmonotonic behavior of the local polarization with doping for strong interactions, which we attribute to the evolution from an antiferromagnetic insulator to a metallic phase. Our results pave the way to experimentally mapping ...


Magnetic Properties Of A Novel Iron Carbide Film, Fe₇C₃X Formed In A Glow Discharge, Oran Allan Pringle, Gary J. Long, Fernande Grandjean, Jun L. Li, George C. Hadjipanayis, William Joseph James Mar 2017

Magnetic Properties Of A Novel Iron Carbide Film, Fe₇C₃X Formed In A Glow Discharge, Oran Allan Pringle, Gary J. Long, Fernande Grandjean, Jun L. Li, George C. Hadjipanayis, William Joseph James

Gary J. Long

No abstract provided.


Comparative Mössbauer Effect Study Of Several R2Fe17 And R2Fe17NX Compounds, Gary J. Long, Sanjay R. Mishra, Oran Allan Pringle, Fernande Grandjean, K. H. Buschow Mar 2017

Comparative Mössbauer Effect Study Of Several R2Fe17 And R2Fe17NX Compounds, Gary J. Long, Sanjay R. Mishra, Oran Allan Pringle, Fernande Grandjean, K. H. Buschow

Gary J. Long

The Mössbauer spectra of Sm2Fe17 and Ho 2Fe17 and their nitrides have been measured between 295 and 85 K and analyzed with a model which is consistent with our earlier work on R2Fe17 and R2Fe17Nx compounds, where R is Pr, Nd, and Th. This model is completely consistent throughout these rare-earth compounds and is in agreement with the crystallographic changes occurring upon nitrogenation and with the prediction of band structure calculations. The dramatic increase in Curie temperature in the nitrides results from the expansion of the crystallographic ...


Using Raman Spectroscopy To Improve Hyperpolarized Noble Gas Production For Clinical Lung Imaging Techniques, Jonathan R. Birchall, Nicholas Whiting, Jason G. Skinner, Michael J. Barlow, Boyd M. Goodson Dec 2016

Using Raman Spectroscopy To Improve Hyperpolarized Noble Gas Production For Clinical Lung Imaging Techniques, Jonathan R. Birchall, Nicholas Whiting, Jason G. Skinner, Michael J. Barlow, Boyd M. Goodson

Nicholas Whiting

Spin-exchange optical pumping (SEOP) can be used to “hyperpolarize” 129Xe for human lung MRI. SEOP involves transfer of angular momentum from light to an alkali metal (Rb) vapor, and then onto 129Xe nuclear spins during collisions; collisions between excited Rb and N2 ensure that incident optical energy is nonradiatively converted into heat. However, because variables that govern SEOP are temperature-dependent, the excess heat can complicate efforts to maximize spin polarization—particularly at high laser fluxes and xenon densities. Ultra-low frequency Raman spectroscopy may be used to perform in situ gas temperature measurements to investigate the interplay of energy thermalization and ...