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  • 2000-2004
  • 1985-1989  (6)
  • 1988  (6)
  • 1
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 2261-2262 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Workability of Y-Ba-Cu-O composite wires with a Ag sheath has been studied and multifilamentary Y-Ba-Cu-O superconductors with a Ag matrix have been successfully fabricated. Observations of the wires with a scanning electron microscope reveal that as the areal reduction ratio R increases, the average Y-Ba-Cu-O grain size decreases. The study on the workability of the composite wires reveals that composite wires consisting of the Y-Ba-Cu-O powder and a Ag matrix can be rolled or drawn to any extent by a cold-work process with intermediate annealings at 150 °C for R=∼10. Based on this study, we have succeeded in fabricating a 252 filament Y-Ba-Cu-O wire which shows a Tc (onset) of ∼95 K.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 6392-6395 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Metallurgical studies and optimization of sintering condition to obtain the maximum volume fraction of the high Tc phase (∼110 K) have been made for the Bi-Sr-Ca-Cu-O system. In the differential thermal analysis, double peaks of endothermic reaction at ∼870 and ∼910 °C were observed during the increase of temperature, and a weight loss accompanied each endothermic reaction. Optimum calcining and sintering conditions to obtain a large volume fraction of the high Tc phase were 820 °C×14 h+840 °C×6 h and 875 °C×100 to 200 h in air, respectively. As for the variation of Cu concentration, nominal composition of Bi1Sr1Ca1Cu2Ox gave the maximum volume fraction of the high Tc phase. (For these specimens, sintering time was varied up to 20 days.) Post annealing at 400 °C for 20 h in an oxygen atmosphere after the sintering at 875 °C for 100 to 470 h in air had little effect on the improvement of volume fraction of the high Tc phase. As for the specimen to which Pb is added, however, the post annealing at 400 °C for 20 h increased the volume fraction of the high Tc phase. Scanning electron microscopy showed that the Bi1Sr1Ca1Cu2Ox (nominal composition) specimens sintered at 875 °C for 100 to 470 h consist mostly of well-grown thin layers, while the specimen sintered at 875 °C for 14 h consists mostly of fine pieces of thin layers piling up at random. Electron probe microanalysis revealed that microstructure of the specimen sintered at 875 °C consists of Bi-poor regions and the matrix surrounding them, and that these Bi-poor regions are classified into Cu-rich regions and Ca-rich regions. The superconducting phases of this material are considered to exist in the matrix region. We identified the Cu-rich regions and Ca-rich regions as (Sr0.45, Ca0.55 )3 Cu5 Ox and (Sr0.08, Ca0.92 )2 CuOx, respectively. The average size of these regions increased with increasing time of sintering, although total volume fraction of these regions did not increase.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 6029-6029 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Magnetic detection has been investigated for use in detecting the location of underground pipelines, such as gas and water lines, by inputting a signal current into a pipeline and detecting magnetic field ((approximately-less-than)100 μG) generated by that current. Measurement factors necessary for accurate detection have been experimentally determined and are discussed. From measurements made on signal current distribution (the current flowing in pipes and leaking from them to ground), it has been concluded that detection error is caused by the leakage current, namely, the current to ground. The detection error is due to the noncenter symmetric distribution of the ground current flowing around a pipe. Even though the ground current is inevitable when flowing a signal current into pipes, it is possible to reduce the error by reducing the nonsymmetry by lowering the signal frequency below 10 kHz in this work. The ground current distribution was obtained by measuring the potential difference between two electrodes, both of which were rod shaped and inserted in the ground to the same depth. At low frequencies below 10 kHz, the ground current distribution in a cross section perpendicular to the pipe showed a rather center symmetry around the pipe, while at high frequencies the distribution changed to a noncenter symmetry with a significant current increase in a region near the ground surface. The drastic change in the distribution of the ground current was also confirmed by magnetic field distribution measurements conducted on the ground using three orthogonally arranged magnetic sensors, each with a sensitivity of 1 μG.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 6030-6030 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Recently, it becomes more important to locate the complex piping patterns such as tee, bend, riser, and the others with high accuracy for maintenance and protection of city gas pipelines. Hence, we have developed a new pipe locator system for imaging the complex underground pipelines using magnetic remote sensing techniques. The main framework of this development is the application of the pattern recognition of the magnetic field distribution to the location of buried pipelines in urban areas. The first step for imaging the complex pipelines is to measure the three-dimensional magnetic field distribution with high accuracy which is generated by the passage of the alternating signal current through buried pipeline. For this purpose a portable trolley unit which is capable of scanning the ground to collect data, the 10 three-axes coil sensors with a sensitivity of 1 μG which are aligned in the unit, and a filter system using a FFT signal processor which eliminates urban magnetic noise as high as 10 mG in some cases, were developed. The second step is to process the magnetic field distribution data, to extract the feature of the underground pipeline using the contour diagram and the three-dimensional drawing of the magnetic field, and to identify the complex piping patterns. Further, we recognized that a nonlinear least-square method algorithm for calculation of the pipeline's position was useful to improve the location accuracy.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1433-8580
    Schlagwort(e): Portal triad cross-clamping ; Hepatic warm ischemia ; Portal pooling ; Arterial blood ketone body ratio ; Hepatic energy charge
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effects of hepatic warm ischemia and portal pooling on the viability of the liver were investigated with respect to hepatic energy metabolism by performing intermittent portal triad cross-clamping (Pringle's maneuver) on dogs with or without portosystemic shunt. The dogs were divided into two groups of five: Group 1, non-shunt group, underwent Pringle's maneuver performed for 30 min and declamping for 30 min, a process that was repeated five times; and Group 2, shunt group, underwent the same procedure as Group 1, except for portosystemic shunt using a heparinized hydrophilic catheter between the splenic and jugular veins. The shunt was opened during Pringle's maneuver and was closed immediately at declamping. In the non-shunt group, portal pooling increased and systemic blood pressure decreased when Pringle's maneuver was performed, but in the shunt group portal and systemic blood pressures remained within the normal range. In the non-shunt group, the initial velocity of arterial blood ketone body ratio (KBR) recovery after each declamping significantly (P 〈 0.01) decreased from 0.122 ± 0.016 (per min) after the first declamping to 0.028 ± 0.017 (per min) after the fifth declamping. Hepatic energy charge [= (ATP + 1/2 ADP)/(ATP + ADP + AMP)] decreased from 0.840 ± 0.003 before ischemia to 0.749 ± 0.003 30 min after the fifth declamping (P 〈 0.001). The concentrations of lactate and total amino acids in arterial blood increased. On the other hand, in the shunt group, the initial velocity of KBR recovery and hepatic energy charge showed little change even after the fifth declamping (0.081 ± 0.016 per min and 0.851 ± 0.009, respectively). The concentrations of lactate and total amino acids showed almost no increase. The impairment of hepatic energy metabolism by intermittent portal triad cross-clamping is mainly due to reinflow of pooled-portal blood to the previously ischemic liver, rather than hepatic warm ischemia. The KBR may be useful for determining the degree of impairment of hepatic energy metabolism.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1573-1561
    Schlagwort(e): Antifeedant ; sesquiterpenoid ; drimane ; dialdehyde ; polygodial ; 1-phenylethylamine ; Myzus persicae ; aphid ; Homoptera ; Aphididae ; phytotoxicity ; taste
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract A series of natural drimanes and related synthetic compounds was tested for antifeedant activity against aphids. Polygodial and warburganal were the most active. The synthetic compounds methyl 9α-hydroxydrimenoate and 9α-hydroxydrimenal, although active against lepidopteran larvae, were inactive against aphids. Natural (−)-polygodial and the synthetic (+) isomer showed similar levels of activity as aphid antifeedants and in phytotoxicity, fish toxicity, and human taste tests, but reacted at different rates with enantiomers of 1-phenylethylamine.
    Materialart: Digitale Medien
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