Single-Fiber Access/Metro WDM Ring Architecture for Asymmetric Traffic Applications in Next Generation Networks

The next generation network (NGN) and the speed-up of access lines will sharply increase the demand for one-way applications such as internet protocol television (IP TV) and video on demand (VOD). One-way applications make the downlink bandwidth much larger than the uplink bandwidth. Asymmetric traffic is best supported by using different numbers of wavelengths in the uplink and downlink, which presumes the use of a wavelength division multiplexing (WDM) network. Unfortunately, the existing 2- or 4-fiber ring network architecture is symmetric, and so it cannot efficiently accommodate asymmetric paths. This paper proposes a novel 1-fiber WDM protection ring that offers a cost-effective optical network architecture for asymmetric traffic as well as symmetric traffic. It also proposes a new 1:1 protection switching scheme and automatic protection switching (APS) control protocol that can reduce capital expenditures for optical-electro-optical termination cards and provide nonrevertive protection switching with extra traffic and APS with end-to-end supervision including optical switching fabrics. Moreover, this paper shows that the proposed wavelength switching scheme offers much better network survivability after multiple wavelength failures than the existing bidirectional switching scheme can offer.     

Degradation of dibutyltin in sea water by pyoverdins isolated from Pseudomonas chlororaphis

The yellow compounds pyoverdins were isolated from Pseudomonas chlororaphis, which was isolated from mud in Japan. Degradation of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) by pyoverdin (20 mg) was carried in sea water (30 ml) containing a 6 µg l^?1 concentration of TBT, DBT, and MBT at 24 °C for 24 h in aerobic conditions. TBT, DBT, and MBT in sea water were analyzed by gas chromatography–mass spectrometry in selected ion monitoring mode. DBT in sea water was degraded to MBT by pyoverdins isolated from P. chlororaphis. However, TBT and MBT in sea water was not degraded by pyoverdins. The optimum degradation of DBT in sea water was at pH 4.8–8.2, at a temperature 25–30 °C. Copyright © 2002 John Wiley & Sons, Ltd.     

Three-dimensional STEM for observing nanostructures

A new scanning transmission electron microscope has been developed for three-dimensional (3D) observations of nanostructures. Using double spherical fulcra, accurate eucentric rotation was achieved. Cylindrical specimens for 3D-observation were prepared by a microsampling technique using a focused ion beam. Copper via-holes of a semiconductor memory device and ZnO particles were observed by the 3D-STEM from different directions, and 3D-data of the ZnO particles were successfully reconstructed in a topography mode.     

Catalytic Cracking of Naphtha to Light Olefins

A catalytic process that produces light olefins from naphtha was developed to improve the yield of the conventional steam cracker. In laboratory-scale tests, a newly developed zeolite-based catalyst at a reaction temperature of 650°C produced an ethylene-plus-propylene yield of about 60%, which is about 10% higher than the conventional process operated at around 820°C. A feasibility study carried out for a catalytic cracking process using the developed catalyst, that cracks 3000 tons-naphtha/day, indicated an energy saving of about 20% compared with the conventional process.     

Doppler-free resonant Raman auger spectroscopy of Ne+ 2s2p(5)3p excited states

Using very high resolution achieved by the Doppler-free resonant Raman Auger technique, we have resolved the lowest terms of the series of inner-valence excitations 2s2p(5)((1,3)P)np 2S, 2P, and 2D in Ne+. The measured Auger anisotropic parameters and branching ratios help to establish the assignments of these levels. The measured lifetime widths are in reasonable agreements with ab initio calculations available in the literature.     

Organocatalytic Activation of the Leaving Group in the Intramolecular Asymmetric SN2′ Reaction

A Brønsted‐acid‐catalyzed intramolecular enantioselective S_N2′ reaction was developed utilizing trichloroacetimidate as a leaving group. The findings indicated that dual activation of the substrates is operative. This metal‐free allylic alkylation allows highly enantioselective access to 2‐vinylpyrrolidines bearing various substituents.     

Oscillation criteria for second-order damped nonlinear differential equations with p-Laplacian

This paper is concerned with the oscillation problem for the nonlinear differential equation with a damping term,