Analysis of one-line ground fault surge on simulated overhead distribution line

One-line fault location techniques of intermittent ground fault points on nongrounded distribution lines are necessary to supply steady electric power for customers. This paper proposes a novel method that uses frequency spectra of transient waveforms at a sending end when an intermittent ground fault occurs. In this method, if a ground fault position differs, it causes a different frequency spectrum pattern for the current or voltage transients at a send end (decided by surge reflection phenomena between the sending end and the ground fault point). Comparison between experimental data of one-line ground fault tests on a simulated overhead line (373 m line length, two branch points) and digital simulation analyses shows that the grounded capacitance of a power source transformer was useful in locating the ground fault point. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (1): 52–60, 1997     

Regulation of Polyunsaturated Fatty Acid Biosynthesis by Seaweed Fucoxanthin and Its Metabolite in Cultured Hepatocytes

The effects of a seaweed carotenoid, fucoxanthin, and its physiological metabolite, fucoxanthinol, on the biosynthesis of polyunsaturated fatty acids (PUFA) were investigated using cultured rat hepatoma BRL‐3A. The metabolism of α‐linolenic acid (18:3n‐3) was suppressed by the addition of these carotenoids, resulting in a decrease in the content of eicosapentaenoic acid (20:5n‐3), which suggested a down‐regulation of metabolic enzymes such as fatty acid desaturase and elongase. An increase in the content of docosahexaenoic acid (22:6n‐3), as observed in previous studies in vivo, might be a buffering action to maintain the membrane fluidity. The suppressive effect of fucoxanthinol on ?6 fatty acid desaturase was not at the level of gene expression but due to specific modifications of the protein via a ubiquitin–proteasome system. A proteomic analysis revealed several factors such as phosphatidylethanolamine‐binding protein that might be involved in the observed action of fucoxanthin. These findings will contribute to studies on the elucidation of the precise molecular mechanisms underlying the regulation of PUFA biosynthesis by fucoxanthin.     

Effect of tacticity on the dielectric properties of polystyrene

Dielectric properties of polystyrene (PS) were investigated by measuring electrical conduction current and frequency spectra of complex permittivity at temperatures from 20 to 199 °C. To clarify the effects of tacticity, the properties were compared among two kinds of syndiotactic PS (SPS) with different crystallinity values and one atactic PS (APS). Experimental results indicate that the two SPS samples show a high melting point of about 250 °C. The conductivity is lowest in SPS with the low crystallinity in the whole temperature range from 20 to 199 °C, while APS had a breakdown at 140 °C. Moreover, the low‐crystallinity SPS shows the smallest permittivity values and the smallest increase in dielectric loss factor toward low frequencies among the three samples. The high‐crystallinity SPS has α crystals. Since the density of α crystals is lower than the amorphous region, the charge transport and polarization are easier in the high‐crystallinity SPS than in the low‐crystallinity SPS. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Development of an x-ray diffraction camera used in magnetic fields up to 10 T

A high-field x-ray diffraction (HF-XRD) camera was developed to observe structural changes of magnetic materials in magnetic fields up to 10 T. The instrument mainly consists of a Debye-Scherrer-type camera with a diameter of 80.1 mm, a 10-T cryocooled superconducting magnet with a 100-mm room-temperature bore, an x-ray source, a power supply, and a chiller for the x-ray source. An x-ray detector (image plate) in the HF-XRD camera can be taken out and inserted into the magnet without changing the sample position. The performance of the instrument was tested by measuring the HF-XRD for silicon and ferromagnetic MnBi powders. A change of x-ray diffraction pattern was observed due to the magnetic orientation of MnBi, showing that the instrument is useful for studying field-induced orientation processes and structural properties of field-controlled materials.     

Corrosion Behavior of Aluminum Wire for Overhead Transmission Lines: Investigation and Analysis

The corrosion behavior of aluminum wire used for overhead transmission lines was studied in four corrosion environments: (1) sodium chloride solution, (2) sodium chloride solution with addition of alumina particles, (3) aluminum chloride solution, (4) aluminum chloride solution with addition of alumina particles. The corrosion tests and polarization measurements revealed that environments 2 and 4 with alumina particles roughened and rapidly corroded the surface of the aluminum wire. It is considered that wet and dry environments of overhead transmission lines change aluminum hydroxide, present as a corrosion product, to alumina (aluminum oxide), which acts as an abrasive and weakens the surface of the aluminum wire. It is also shown that the corrosion of the aluminum wire occurs in an abrasive corrosion environment caused by alumina and corrosion fatigue due to vibration of the overhead wires. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 185(4): 18–24, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22486     

Advanced closing switch for three‐phase short‐circuit test of a very fast current limiter

Advanced closing switch for three‐phase short‐circuit test was developed for very fast current limiter using power electronics devices. The conventional short‐circuit test method was used for verification of the current interrupting device with longer time duration to interrupt fault current after the separation of contacts. In the conventional short‐circuit test method, a deviation of the closing time between each phase closing switch with a mechanical driving was regulated so that the breaking performance of the conventional switching device could be examined. However, in the new current limiter with very short fault current interruption time, the deviation time between each phase must be reduced less than the regulated time by the conventional test method. For this purpose, the advanced closing switch for three‐phase short‐circuit test method was developed. In the advanced test method, power electronics devices were used for the initiation of three‐phase short‐circuit fault. Results of the short‐circuit test showed that the advanced circuit had very small deviation time between the initiation of each phase fault. Also, the very fast current limiter with power electronics devices was shown to have an intended interrupting performance. © 1999 Scripta Technica, Electr Eng Jpn, 130(1): 68–75, 2000     

Endoplasmic Reticulum (ER)‐Targeted,Galectin‐Mediated Retrograde Transport by Using a HaloTag Carrier Protein

Investigations into metabolic processes within the cell have often relied on genetic methods such as forced expression and knockout or knockdown techniques. An alternative approach would be introducing a molecule into the desired location inside the cell. To translocate compounds from outside cells into the endoplasmic reticulum (ER), we constructed a delivery carrier protein. This comprised N‐terminal galectin‐1 for cell‐surface binding (G1), a protease cleavable sequence (ps), a HaloTag domain for attaching exogenous compounds (Halo), and a C‐terminal KDEL sequence for ER retention. Fluorescently labeled G1‐ps‐Halo‐KDEL passed through the Golgi apparatus and reached the ER. By using Man₉GlcNAc₂‐BODIPY as a cargo compound, the carrier protein was also delivered into the ER with concomitant processing of mannose to Man_5,6, by the ER‐resident α1,2‐mannosidase. G1‐ps‐Halo‐KDEL might serve as a new type of delivery carrier protein to direct compounds into the ER.     

Ultrahigh-speed pseudomorphic InGaAs/InAlAs HEMTs with 400-GHzcutoff frequency

An excellent cutoff frequency (f_t) as high as 400 GHz was successfully realized in 45-nm-gate pseudomorphic InGaAs/InAlAs high electron mobility transistors (HEMTs). An additional vertical gate-recess suppressed short-channel effects, while keeping good pinchoff characteristics. Gate length (L_g) dependence of electron transit time (τ_transit) implied an increased saturation velocity (υ_s) of 3.6×10⁷ cm/s in the developed pseudomorphic HEMTs. This f_t is the highest value ever reported for any transistors to date     

Electrical conductivity and electromagnetic interference shielding effectiveness of polyaniline–ethylene vinyl acetate composites

Electrical conductivity and electromagnetic interference (EMI) shielding effectiveness at microwave (200–2000 MHz) and X‐band (8–12 GHz) frequency range of polyaniline (PAni) composites were studied. It has been observed that EMI shielding of conductive polyaniline (PAni)–ethylene vinyl acetate composites increases with the increase in the loading levels of the conductive polymer doped with dodecylbenzene sulfonic acid. The result indicates that the composites having higher PAni loading (>23%) can be used for EMI shielding materials and those with lower PAni loading can be used for the dissipation of electrostatic charge. Copyright © 2004 Society of Chemical Industry     

Inhibitory activity of brown algal phlorotannins against hyaluronidase

The inhibitory effect of brown algal phlorotannins on hyaluronidase was evaluated by an in vitro assay. Crude phlorotannins from the brown algae Eisenia bicyclis and Ecklonia kurome had a stronger inhibitory effect than well-known inhibitors such as catechins and sodium cromoglycate. IC₅₀ values of the following six phlorotannins: phloroglucinol, an unknown tetramer, eckol (a trimer), phlorofucofuroeckol A (a pentamer), dieckol and 8,8'-bieckol (hexamers), were 280, 650, >800, 140, 120 and 40 μ M , respectively. The IC₅₀ of catechin, epigallocatechin gallate and sodium cromoglycate was 620, 190 and 270 μ M , respectively. 8,8'-Bieckol, the strongest HAase inhibitor in this study, acted as a competitive inhibitor with an inhibition constant ( K _i) of 35 μ M . Acetylation of the phlorotannins markedly decreased their inhibitory potency.