Menadione-catalyzed luminol chemiluminescence assay for the rapid detection of viable bacteria in foods under aerobic conditions

A menadione-catalyzed luminol chemiluminescence assay was developed for the rapid detection and estimation of viable bacteria in foods. The principle of this assay is based on the extracellular menadione-catalyzed active oxygen spieces (O2- and H2O2) generated by the activity of NAD(P)H:menadione oxidoreductase in viable cells. This luminol chemiluminescence assay requires 10 min for the incubation of cells with menadione and then 2 s for the measurement of chemiluminescence intensity after an injection of luminol solution without the treatment of cell lysis. This method was evaluated using liquid food samples of milk, vegetable juice, green tea, and coffee spiked with Escherichia coli ATCC 25922. The study result revealed that E. coli contamination at 1 to 10 CFU/ml in these foods could be detected after incubation at 37 degrees C for 7 h in an enrichment medium; however, the green tea and coffee samples requires filtration. This method could be a useful tool for the rapid evaluation of microbial food contamination.     

Characteristics of lightning strikes on wind turbine blades. Experimental study of the effects of receptor configuration and other parameters

The characteristics of lightning strikes on wind turbine blades have been investigated by model experiments with real turbine blades. The effects of various types of receptors, the polarities of the applied voltages, and pollution on the blade surface are clarified. Based on these experimental results, lightning protection design of actual wind turbine blades by receptors is discussed. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(3): 8–18, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21143     

Quantitative analysis of mycoflora on commercial domestic fruits in Japan

A comprehensive and quantitative analysis of the mycoflora on the surface of commercial fruit was performed. Nine kinds of fruits grown in Japan were tested. Overall fungal counts on the fruits ranged from 3.1 to 6.5 log CFU/g. The mean percentages of the total yeast counts were higher than those of molds in samples of apples, Japanese pears, and strawberries, ranging from 58.5 to 67.0%, and were lower than those of molds in samples of the other six fruits, ranging from 9.8 to 48.3%. Cladosporium was the most frequent fungus and was found in samples of all nine types of fruits, followed by Penicillium found in eight types of fruits. The fungi with the highest total counts in samples of the various fruits were Acremonium in cantaloupe melons (47.6% of the total fungal count), Aspergillus in grapes (32.2%), Aureobasidium in apples (21.3%), blueberries (63.6%), and peaches (33.6%), Cladosporium in strawberries (38.4%), Cryptococcus in Japanese pears (37.6%), Penicillium in mandarins (22.3%), and Sporobolomyces in lemons (26.9%). These results demonstrated that the mycoflora on the surfaces of these fruits mainly consists of common pre- and postharvest inhabitants of the plants or in the environment; fungi that produce mycotoxins or cause market diseases were not prominent in the mycoflora of healthy fruits. These findings suggest fruits should be handled carefully with consideration given to fungal contaminants, including nonpathogenic fungi, to control the quality of fruits and processed fruit products.     

Generation mechanism of electrochemical migration in printed wiring board insulation

In order to study the generation mechanism of electrochemical migration in a printed wiring board, paper/phenol‐resin composites with and without an adhesive layer, epoxy resin, and a laminate of epoxy resin and a paper/phenol‐resin composite were aged at 85 °C and 85% relative humidity (RH) with and without application of a DC voltage, and the space charge distributions in the samples were observed by the pulsed electroacoustic method. In the case of the composite with the adhesive layer, a large amount of negative charge is induced at the interface between the composite and the adhesive layer on the anode. It was found that such formation of space charge enhances the electric field intensity at the anode. The reason for this is because the conductivity is much lower in the adhesive layer than in the composite. Electrochemical migration does not occur when the same electric field is applied to the composite without the adhesive layer, whereas it does occur if the adhesive layer was replaced by epoxy resin with a similar conductivity to the adhesive layer. These results clearly indicate that electrochemical migration generates because the electric field at the anode surface is enhanced due to the low conductivity of the adhesive layer. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Theoretical consideration on the number of external degrees of freedom and its application to poly(dimethylsiloxane) solutions

Summary The Flory theory of polymer solution was modified by assuming the non-additivity of the number of the degree of external freedom for a binary mixture and applied the modified Flory theory to poly (dimethylsiloxane)-solvent systems. This theory can reproduce the experimental results of the interaction parameter and the excess volume of mixing, which the Flory theory failed to reproduce.     

Multimode Bragg diffractions in an ion-exchanged optical waveguide with a sputter-etched periodic surface corrugation

An optical diffraction phenomenon in an ion-exchanged planar optical waveguide with a sputter-etched periodic surface corrugation was experimentally investigated in detail. A single-mode incident beam simultaneously gave rise to several diffracted beams of different mode indices in different directions. This phenomenon was interpreted on the basis of the phase-matching diagram for the multimode Bragg diffraction by using measured wave vectors of the propagation modes and of the surface corrugation.     

Colorimetric determination of peroxide value with potassium iodide-silica gel reagent

A micro-determination of peroxide value is proposed. The iodine liberated from potassium iodide-silica gel reagent with peroxides in the oil was complexed with starch in 0.01 N hydrochloric acid. The blue color was then measured colorimetrically at 560 nm.     

Development of optical fiber/power line composite tether cable for remotely operated unmanned submersible

A new type of tether cable with high quality signal transmission characteristics was developed by adopting optical fibers. As the tether cable is subject to frequent and various mechanical and thermal loads under the severe operating conditions in the offshore environment, the greatest care should be paid to the design of its structure to preserve the optical fibers from those loads. This paper describes the design requirements and the characteristics of the optical fiber/power line composite tether cable under the loads such as tensile loading, bending, twisting, water pressure, and cable heating. The termination of the tether cable is also discussed. This tether cable has been in practical use for remotely operated submersible MARCAS whose mission is inspection and location of the submarine telecommunication cables.     

Countermeasures for controlling lightning‐caused overvoltage on indoor wiring with communication line

Overvoltage generated by lightning is a threat to indoor electrical equipment in our information‐oriented and computerized society. Countermeasures for preventing overvoltage on indoor wiring are demanded. Therefore, we have investigated the effectiveness of some countermeasures, such as low‐voltage arresters, communication line arresters, SPDs, and a common grounding wire, for reducing the overvoltage on indoor wiring with a communication line. In particular, we have studied the effect of the combination of these countermeasures and their layout on controlling the overvoltage, using a full‐scale test distribution line with a customer's facility. The main results are as follows:

• (1) A common grounding wire installed along the low‐voltage indoor wiring is more effective for reducing the overvoltage on the indoor wiring with a communication line than is one installed under the floor, when the arresters are installed at the panel board.
• (2) Combination of an SPD and other countermeasures, such as low‐voltage arresters and a common grounding wire, is effective for controlling the overvoltage on the indoor wiring, and the effectiveness of these countermeasures for preventing damage of electrical equipment has been verified by an experiment using actual electrical equipment. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(1): 37–45, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10223