Heats of Mixing of Binary Mixtures of n-Butylamine with Water, Methanol, Ethanol & n-Butan-I-ol: Effect of the Chain Length on Hydrogen Bond Energy

735-74

Transition from internal to external oxidation in indium-silver alloys

The kinetics of oxidation of In-Ag alloys of 5,10, and 15 at. % indium have been studied on a vacuum microbalance. The 15 at. % indium alloy oxidizes externally and the 5 at. % alloy internally. A plot of logarithm of the parabolic oxidation rate, kp, versus reciprocal of the absolute temperature for 10 at. % indium alloy gives two intersecting straight lines corresponding to the energies of activation of 23 and 39.6 kcal/mole for the oxidation below and above 600°C respectively. These are comparable to the energies of activation of 23 kcal/mole for the internal oxidation of 5 at. % indium alloy and 40 kcal/mole for the external oxidation of 15 at. % indium alloy. The rate-controlling step in the external oxidation of 15 at. % indium alloy is the diffusion of indium through the alloy. Photomicrographs of the cross sections of the oxidized foils of these alloys confirm the conclusions derived from the kinetic data

Thermodynamic Properties of I-Propanol + n-Butylamine Binary Mixture: Enthalpy of Hydrogen Bonding

371-37

Uncovering Low-Dimensional Topological Structure in the QCD Vacuum

Recently, we have pointed out that sign-coherent 4-dimensional structures can not dominate topological charge fluctuations in QCD vacuum at all scales. Here we show that an enhanced lower-dimensional coherence is possible. In pure SU(3) lattice gauge theory we find that in a typical equilibrium configuration about 80% of space-time points are covered by two oppositely-charged connected structures built of elementary 3-dimensional coherent hypercubes. The hypercubes within the structure are connected through 2-dimensional common faces. We suggest that this coherence is a manifestation of a low-dimensional order present in the QCD vacuum. The use of a topological charge density associated with Ginsparg-Wilson fermions ("chiral smoothing") is crucial for observing this structure.Comment: 3 pages, 1 figure; Proceedings of the "Confinement V" Conference, Gargnano, Italy, Sep 10-14, 200

The Negativity of the Overlap-Based Topological Charge Density Correlator in Pure-Glue QCD and the Non-Integrable Nature of its Contact Part

We calculate the lattice two-point function of topological charge density in pure-glue QCD using the discretization of the operator based on the overlap Dirac matrix. Utilizing data at three lattice spacings it is shown that the continuum limit of the correlator complies with the requirement of non-positivity at non-zero distances. For our choice of the overlap operator and the Iwasaki gauge action we find that the size of the positive core is ~2a (with a being the lattice spacing) sufficiently close to the continuum limit. This result confirms that the overlap-based topological charge density is a valid local operator over realistic backgrounds contributing to the QCD path integral, and is important for the consistency of recent results indicating the existence of a low-dimensional global brane-like topological structure in the QCD vacuum. We also confirm the divergent short-distance behavior of the correlator, and the non-integrable nature of the associated contact part.Comment: 13 pages, 5 figure

Crossover of conductance and local density of states in a single-channel disordered quantum wire

The probability distribution of the mesoscopic local density of states (LDOS) for a single-channel disordered quantum wire with chiral symmetry is computed in two different geometries. An approximate ansatz is proposed to describe the crossover of the probability distributions for the conductance and LDOS between the chiral and standard symmetry classes of a single-channel disordered quantum wire. The accuracy of this ansatz is discussed by comparison with a large-deviation ansatz introduced by Schomerus and Titov in Phys. Rev. B \textbf{67}, 100201(R) (2003).Comment: 19 pages, 5 eps figure

Numerical Simulation of Magnetic Interactions in Polycrystalline YFeO3

The magnetic behavior of polycrystalline yttrium orthoferrite was studied from the experimental and theoretical points of view. Magnetization measurements up to 170 kOe were carried out on a single-phase YFeO3 sample synthesized from heterobimetallic alkoxides. The complex interplay between weak-ferromagnetic and antiferromagnetic interactions, observed in the experimental M(H) curves, was successfully simulated by locally minimizing the magnetic energy of two interacting Fe sublattices. The resulting values of exchange field (H_E = 5590 kOe), anisotropy field (H_A = 0.5 kOe) and Dzyaloshinsky-Moriya antisymmetric field (H_D = 149 kOe) are in good agreement with previous reports on this system.Comment: 26 pages, 9 figure