Early stage morphology of quench condensed Ag, Pb and Pb/Ag hybrid films

Scanning Tunneling Microscopy (STM) has been used to study the morphology of Ag, Pb and Pb/Ag bilayer films fabricated by quench condensation of the elements onto cold (T=77K), inert and atomically flat Highly Oriented Pyrolytic Graphite (HOPG) substrates. All films are thinner than 10 nm and show a granular structure that is consistent with earlier studies of QC films. The average lateral diameter, $\bar {2r}$, of the Ag grains, however, depends on whether the Ag is deposited directly on HOPG ($\bar {2r}$ = 13 nm) or on a Pb film consisting of a single layer of Pb grains ($\bar {2r}$ = 26.8 nm). In addition, the critical thickness for electrical conduction ($d_{G}$) of Pb/Ag films on inert glass substrates is substantially larger than for pure Ag films. These results are evidence that the structure of the underlying substrate exerts an influence on the size of the grains in QC films. We propose a qualitative explanation for this previously unencountered phenomenon.Comment: 11 pages, 3 figures and one tabl

The Effect of Nitrided Layer on Antibacterial Properties for Biomedical Stainless Steel

AbstractPlasma nitriding of AISI type 303 austenitic stainless steel using microwave system at various input powers was conducted in present study. The nitrided layers were characterized via scanning electron microscopy, transmission electron microscopy and Vickers microhardness tester. The anti-bacterial property of this nitrided layer was also evaluated. The analytical results revealed the hardness of AISI type 303 stainless steel could be enhanced with nitriding process. The microstructure of the nitrided layer comprised of nitrogen-expanded γ phase. Bacterial test demonstrated the nitrided layer processed the excellent an ti-bacterial properties. The enhanced hardness and anti-bacterial properties make the nitrided AISI type 303 austenitic stainless steel the potential material in the biomedical applications

Multiplier-less low-delay FIR and IIR wavelet filter banks with SOPOT coefficients

In this paper, a new family of multiplier-less two-channel low-delay wavelet filter banks using the PR structure in [3] and the SOPOT(sum-of-powers-of-two) representation is proposed. In particular, the functions α(z) and β(z) in the structure are chosen as nonlinear-phase FIR and IIR filters, and the design of such multiplier-less filter banks is performed using the genetic algorithm. The proposed design method is very simple to use, and is sufficiently general to construct low-delay wavelet bases with flexible length, delay, and number of zero at π (or 0) in their analysis filters. Several design examples are given to demonstrate the usefulness of the proposed method

Neoclassical tearing modes in DIII-D and calculations of the stabilizing effects of localized electron cyclotron current drive

Neoclassical tearing modes are found to limit the achievable beta in many high performance discharges in DIII-D. Electron cyclotron current drive within the magnetic islands formed as the tearing mode grows has been proposed as a means of stabilizing these modes or reducing their amplitude, thereby increasing the beta limit by a factor around 1.5. Some experimental success has been obtained previously on Asdex-U. Here the authors examine the parameter range in DIII-C in which this effect can best be studied

Anomalous Hopping Exponents of Ultrathin Films of Metals

The temperature dependence of the resistance R(T) of ultrathin quench-condensed films of Ag, Bi, Pb and Pd has been investigated. In the most resistive films, R(T)=Roexp(To/T)^x, where x=0.75. Surprisingly, the exponent x was found to be constant for a wide range of Ro and To in all four materials, possibly implying a consistent underlying conduction mechanism. The results are discussed in terms of several different models of hopping conduction.Comment: 6 pages, 5 figure