Accurate modeling of dielectric interfaces by the effective permittivities for the fourth-order symplectic finite-difference time-domain method

The fourth-order finite-difference time-domain (FDTD) method using a symplectic integrator propagator can calculate the propagation of the electromagnetic waves with very low dispersion error in the region of a constant or smoothly varying index profile. An additional technique is required for the problem with the discontinuous dielectric interfaces. We derived the third-order effective permittivities at dielectric interfaces for the fourth-order FDTD method in the case of 2D TE polarization. As the required accuracy level is increased, the memory resources used by the fourth-order FDTD method with the effective permittivities are reduced severalfold or more compared with the standard FDTD method. The accurate performance of the proposed method is demonstrated through numerical examples.     

Production of nanopatterns by a combination of electron beam lithography and a self-assembled monolayer for an antibody nanoarray

We report on a flexible method of producing antibody (IgG) nanopatterns by combining electron beam (EB) lithography and a perfluorodecyltriethoxysilane (FDTES) self-assembled monolayer (SAM). Using EB lithography of the FDTES SAM, we easily fabricated IgG patterns with feature sizes on the order of 100 nm. The patterned IgG retained its ability to interact specifically with an anti-LgG. The influence of different concentrations of the IgG and anti-IgG on the resulting fluorescent IgG arrays was investigated. These IgG nanopatterns appeared to be remarkably well controlled and showed almost no detectable nonspecific binding of proteins on a hydrophobic SAM under a suitable incubation condition, characterized by atomic force microscopy, and epi-fluorescence microscopy. The technique enables the realization of high-throughput protein nanoscale arrays with high specificity.     

Formation of one-way-structured cultured neuronal networks in microfluidic devices combining with micropatterning techniques

We present a simple method to regulate the direction of axon development in cultured neurons using microfabrication and microfluidics techniques. We fabricate a PDMS-based device and place it onto a chemically micropatterned glass substrate. We confirm that cultured neurons extend neurites along the medium flow direction and the micropatterned regions.     

CHARACTERIZATION OF SELENIUM CATALYST FOR COAL LIQUEFACTION IN TERMS OF HYDROGENATION AND CRACKING ABILITY

ABSTRACT

The activities of selenium and zinc chloride catalysts upon transferable hydrogen in coal have been investigated by ^IH-NMR. Se is more active than ZnCl₂ for hydrogen transfer in the coal/anthracene system. The change of radical concentration was monitored by high temperature ESR. It was confirmed that radical concentration in the coal/Se system is greater than that in the coal/ZnCl₂ system at the early stage of pyrolysis. It was concluded that Se has a higher cracking activity as well as hydrogen transfer ability and there is the potential for the use of Se as a catalyst for coal liquefaction.     

The effect of helium environment on the creep rupture properties of Inconel 617 at 1000°C

The effect of oxygen contents in helium and in vacuum on the creep rupture properties of Inconel 617 has been investigated at 1000°C under the stress of 3.5 Kg/mm². The main results are as follows. 1) The creep rupture properties in 99.9999 pct and 99.995 pct helium and in high vacuum are almost the same as those in air. 2) The oxygen in helium causes a remarkable decrease of the creep rupture time and similar effect of oxygen is also found in the controlled pressure of air. 3) The effect of oxygen on the creep rupture properties is attributable to the decarburization which tends to decrease the high temperature strength.     

Anomalous behavior of electrical conductivity of solubilized collagen solutions with thermal denaturation

The temperature dependence of the electrical conductivity, σ, for a collagen solution was measured in the temperature region including the thermal denaturation temperature, t_d. The σ increased with temperature, t, but decreased at ca. 40°C, and then again increased. In this temperature region, a change of optical rotation, α_D, was observed. The change is due to the thermal denaturation. The differential curve of σ vs. t gave clear deflection points and a large peak at ca. 40°C. The t_d could be estimated from the peak temperature. The t_d decreased with the increase in the concentration of collagen and with the decrease in the heating rate. These measurements were carried out for the collagen prepared by various methods. Some of them showed one peak; others had two peaks. The t_d obtained by the measurement of σ correlated with that obtained by the measurement of α_D. The activation energy of σ, ΔE_a, obtained from the linear relationship between log σ and 1/T, increased with the concentration of collagen, but was unchanged for the heating rate. The ΔE_a obtained for various types of collagen showed a constant value. © 1993 John Wiley & Sons, Inc.     

A Lyapunov-density criterion for almost everywhere stability of a class of Lipschitz continuous and almost everywhere C1 nonlinear systems

This paper is concerned with the analysis of almost everywhere stability (AES) of a class of nonlinear systems via Lyapunov densities. While many of the previous results on Lyapunov densities assume that the vector field is continuously differentiable, this paper deals with nonlinear systems that can have points of non-differentiability. A key to prove AES is monotonicity of a measure defined with a Lyapunov density to deduce that the set of non-convergent initial values has zero Lebesgue measure. The monotonicity condition of a measure involves a change of variables in integrals of the Lyapunov density over a set. Such a change of variables along trajectories is not available for vector fields that are not globally continuously differentiable, even though they are smooth at almost all points of the state space. In this paper, an alternative inequality is presented that proves monotonicity of a measure along trajectories of a class of nonlinear systems that are Lipschitz continuous and almost everywhere continuously differentiable. Based on this inequality, we provide a sufficient condition for AES while guaranteeing positive invariance of a specified region.     

Analysis and demonstration of single-passband response and tuning characteristics in a chirped ladder interferometric filter for a widely tunable laser diode

We have designed and demonstrated a chirped ladder-type tunable filter and discussed its potential application for a tunable diode laser. A ladder interferometric filter normally has a periodic passband, which makes it impossible to stabilize laser oscillation frequency. To overcome this drawback, we have designed, fabricated, and characterized a novel chirped tunable ladder filter. We have successfully demonstrated a single-passband response in the fabricated device. Furthermore, a tuning operation of more than 30 nm was achieved by introducing a current injection structure and optimizing electrode lengths at each single-stage ladder interferometer.