Phase transition from hadronic matter to quark matter

We study the phase transition from nuclear matter to quark matter within the SU(3) quark mean field model and NJL model. The SU(3) quark mean field model is used to give the equation of state for nuclear matter, while the equation of state for color superconducting quark matter is calculated within the NJL model. It is found that at low temperature, the phase transition from nuclear to color superconducting quark matter will take place when the density is of order 2.5$\rho_0$ - 5$\rho_0$. At zero density, the quark phase will appear when the temperature is larger than about 148 MeV. The phase transition from nuclear matter to quark matter is always first order, whereas the transition between color superconducting quark matter and normal quark matter is second order.Comment: 18 pages, 11 figure

Band-collision gel electrophoresis.

Electrophoretic mobility shift assays are widely used in gel electrophoresis to study binding interactions between different molecular species loaded into the same well. However, shift assays can access only a subset of reaction possibilities that could be otherwise seen if separate bands of reagent species might instead be collisionally reacted. Here, we adapt gel electrophoresis by fabricating two or more wells in the same lane, loading these wells with different reagent species, and applying an electric field, thereby producing collisional reactions between propagating pulse-like bands of these species, which we image optically. For certain pairs of anionic and cationic dyes, propagating bands pass through each other unperturbed; yet, for other pairs, we observe complexing and precipitation reactions, indicating strong attractive interactions. We generalize this band-collision gel electrophoresis (BCGE) approach to other reaction types, including acid-base, ligand exchange, and redox, as well as to colloidal species in passivated large-pore gels

Multiwavelength optical pyrometer for shock compression experiments

A system for measurement of the spectral radiance of materials shocked to high pressures (~100 GPa) by impact using a light gas gun is described. Thermal radiation from the sample is sampled at six wavelength bands in the visible spectrum, and each signal is separately detected by solid-state photodiodes, and recorded with a time resolution of ~10 ns. Interpretation of the records in terms of temperature of transparent sample materials is discussed. Results of a series of exploratory experiments with metals are also given. Shock temperatures in the range 4000–8000 K have been reliably measured. Spectral radiance and temperatures have been determined with uncertainties of 2%

Memristive switching of MgO based magnetic tunnel junctions

Here we demonstrate that both, tunnel magneto resistance (TMR) and resistive switching (RS), can be observed simultaneously in nano-scale magnetic tunnel junctions. The devices show bipolar RS of 6 % and TMR ratios of about 100 %. For each magnetic state, multiple resistive sates are created depending on the bias history which provides a method for multi-bit data storage and logic. The electronic transport measurements are discussed in the framework of a memristive system. Differently prepared MgO barriers are compared to gain insight into the switching mechanism

Characterization of a new iron-on-zeolite Y Fischer-Tropsch catalyst

Iron pentacarbonyl adsorbed on dry Na-Y zeolite can be oxidized at subambient temperatures into Fe203 located in the zeolite supercages (catalyst I). When catalyst I is hydrogen reduced at 575 K most of the iron has agglomerated externally to the zeolite (catalyst 11). When the iron carbonyl is thermally decomposed in vacuo at 525 K, an iron phase with a very low degree of dispersion is again obtained (catalyst 111). During a Fischer-Tropsch reaction most of the iron is transformed into a Hagg-type carbide phase, located externally to the zeolite. Catalysts I1 and 111 rapidly reach steady state and show a Schulz-Flory-type of product distribution, the Hagg carbide being the active phase. Catalyst I slowly moves to steady state and Schulz-Flory behavior. Product selectivity is only found on this catalyst during transient conditions. The physical information on the three catalysts before and after reaction was obtained with transmission electron microscopy and Mossbauer and EXAFS spectroscopies. These techniques supplied consistent and complementary evidenc

Kinetic Theory of Flocking: Derivation of Hydrodynamic Equations

It is shown how to explicitly coarse-grain the microscopic dynamics of the Vicsek model for self-propelled agents. The macroscopic transport equations are derived by means of an Enskog-type kinetic theory. Expressions for all transport coefficients at large particle speed are given. The phase transition from a disordered to a flocking state is studied numerically and analytically.Comment: 4 pages, 1 figur

Comparison of Nucleon Form Factors from Lattice QCD Against the Light Front Cloudy Bag Model and Extrapolation to the Physical Mass Regime

We explore the possibility of extrapolating state of the art lattice QCD calculations of nucleon form factors to the physical regime. We find that the lattice results can be reproduced using the Light Front Cloudy Bag Model by letting its parameters be analytic functions of the quark mass. We then use the model to extend the lattice calculations to large values of Q^{2} of interest to current and planned experiments. These functions are also used to define extrapolations to the physical value of the pion mass, thereby allowing us to study how the predicted zero in G_{E}(Q^{2})/G_{M}(Q^{2}) varies as a function of quark mass.Comment: 31 pages, 22 figure