Incident wavelength dependence of pulse responses in InP/InGaAsP/InGaAs avalanche photodiodes

Pulse responses of InP/InGaAsP/InGaAs APDs have been studied at 1.3 and 1.55 ?m. A faster response rise-up characteristic was observed at 1.55 ?m than at 1.3 ?m. This result indicates that response speed depends on the hole generating region and hole pile-up at the heterojunction is decreased by introducing a hole-acceleration layer such as InGaAsP.     

Translocation of inorganic/organic mercury in a model aquatic system

The volatile organic mercury at subnanogram level was determined by steam distillation-Magos treatment and flameless atomic absorption spectrophotometry after preconcentration with silvered sand. By this technique, down to 0.1 ng of methyl mercury can be determined with good precision (±5%). Application of the technique to our aquatic model system made clear that much higher ratio of organic mercury (nearly 8%) to the total one was in water overlying organic sediment than the water sample overlying sandy sediment (approx. 3.5%). In natural water, therefore, it would seem that the content of organomercurials are less than 10% to that of total mercury.     

Accumulation of S-2-hydroxyethyl derivatives of L-cysteine and L-homocysteine by a methionine auxotroph of Escherichia coli with the addition of 2-mercaptoethanol to the culture

We previously reported [J. Biosci. Bioeng., 94, 178-181 (2002)] that an Escherichia coli MetC-deficient mutant can accumulate L-cystathionine. When 2-mercaptoethanol was added to the culture medium during fermentation, the accumulation of L-cystathionine decreased and S-(2-hydroxyethyl)-L-cysteine and S-(2-hydroxyethyl)-L-homocysteine were accumulated.     

Analysis of the energy‐based swing‐up control of the Acrobot

This paper addresses the energy‐based swing‐up control problem for the Acrobot, a two‐link underactuated robot with a single actuator at the joint of the two links. In line with the energy‐based control approach, this paper presents a necessary and sufficient condition for non‐existence of any singular point in the derived control law, and provides a complete analysis of the convergence of the energy and the motion of the Acrobot. Specifically, for any initial state of the Acrobot, this paper shows clearly how to choose control parameters such that the Acrobot will eventually either be swung up to any arbitrarily small neighbourhood of the upright equilibrium point, or remain in a set containing a finite number of equilibrium points. Moreover, this paper shows that these equilibrium points are unstable. Furthermore, imposing a stronger condition on a control parameter yields that the equilibrium set contains only the downward equilibrium point, which is shown to be hyperbolic and unstable. This proves that the Acrobot will eventually enter the basin of attraction of any stabilizing controller for all initial conditions with the exception of a set of Lebesgue measure zero. Copyright © 2007 John Wiley & Sons, Ltd.     

An estimation method for basemat uplift behavior of nuclear power plant buildings

It is important to accurately estimate the effects of strong earthquake motions on the basemat uplift behavior and structural responses for the seismic design of nuclear power plant buildings. In this paper, an analysis model which describes the soil part using the 3 dimensional FEM was proposed to be used when the ground contact ratio is low, and the validity of this model was confirmed. Furthermore, investigations using the model were carried out where the attaching force under the basemat was taken into account, in order to more realistically estimate the basemat uplift behavior. The effects in the case of the building being embedded were also investigated.     

Surface modification of calcium metaphosphate fibers

-calcium metaphosphate fibers having high aspect ratios of 10–120 with diameters of 2–10 m show high strength and good biocompatibility. When the fibers are soaked in simulated body fluid at 37 °C, however, no calcium phosphate phase is newly formed on the fibers. In the present work, by treating the fibers at 70 °C with dilute NaOH aqueous solution, the surface phase was converted successfully into the orthophosphate phase that was in fine sizes and was adhered. After soaking the treated fibers in simulated body fluid at 37 °C for 30 days, a new calcium phosphate phase was precipitated. This was attributed to the surface phase modified using dilute NaOH. The treated fibers are expected to show bone-bonding ability, i.e. bioactivity. ©2000 Kluwer Academic Publishers     

Controlling the aggregation behavior of gold nanoparticles

The aggregation of Au nanoparticles (NPs) in solution is influenced by cationic and oligocationic species. The polarization of the conduction electron oscillations in adjacent gold nanoparticles causes a new red-shifted plasmon absorbance attributed to the coupling of the plasmon absorbance of the particles. This appearance of an additional plasmon band is of particular interest to the field of SERS and has led to research works directed at the stabilization of small colloid aggregates in solution. The surface plasmon coupling can be tuned by controlling the aggregation of gold nanoparticles by the addition of some “cross-linking” agent. Here we develop a simple method to fabricate linear-chainlike aggregates of gold nanoparticles (so-called nanochains), tuning the linear optical properties in a wide wavelength range from visible to the near-infrared. The aggregation behavior and linear self-assembly mechanism of citrate-stabilized gold colloids as provoked by the addition of cetyltrimethylammonium bromide (CTAB) and 11-mercaptoundecanoic acid (MUA) are also analyzed. The line-assembly mechanism of gold nanochain is attributed to the preferential binding of CTAB molecules on a certain facet of gold NPs and the Au NP electrostatic interactions. We also found that the 11-mercaptoundecanoic acid was effective to prevent the further aggregation of CTAB-modified gold colloids.     

Table form document analysis based on the document structure grammar

Structure analysis of table form documents is an important issue because a printed document and even an electronic document do not provide logical structural information but merely geometrical layout and lexical information. To handle these documents automatically, logical structure information is necessary. In this paper, we first analyze the elements of the form documents from a communication point of view and retrieve the grammatical elements that appear in them. Then, we present a document structure grammar which governs the logical structure of the form documents. Finally, we propose a structure analysis system of the table form documents based on the grammar. By using grammar notation, we can easily modify and keep it consistent, as the rules are relatively simple. Another advantage of using grammar notation is that it can be used for generating documents only from logical structure. In our system, documents are assumed to be composed of a set of boxes and they are classified as seven box types. Then the box relations between the indication box and its associated entry box are analyzed based on the semantic and geometric knowledge defined in the document structure grammar. Experimental results have shown that the system successfully analyzed several kinds of table forms.