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  • 1
    Electronic Resource
    Electronic Resource
    Red algae as hosts for endophytic kelp gametophytes (1999)
    Springer
    Marine biology 135 (1999), S. 35-40 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We observed kelp gametophytes endophytic in the cell walls of 17 species of red algae from the San Juan Islands, Washington, USA. Host algae were collected primarily from three sites dominated by different kelp assemblages, including (1) a subtidal site dominated by Agarum fimbriatum Harvey, (2) a second subtidal site dominated by Nereocystis luetkeana (Mertens) Postels et Ruprecht, and (3) a floating dock on which the dominant kelp species were Alaria marginata Postels et Ruprecht, Laminaria groenlandica Rosenvinge, and Costaria costata (C. Agardh) Saunders. Most hosts were filamentous [e.g. Pleonosporium vancouverianum (J. Agardh) J. Agardh, Callithamnion acutum Kylin], or polysiphonous [e.g. Polysiphonia paniculata Montagne, Pterosiphonia dendroidea (Montagne) Falkenberg]; however, similar endophytes were also observed in membranous or bladed red algae [e.g. Membranoptera platyphylla (Setchell et Gardner) Kylin, Polyneura latissima (Harvey) Kylin]. Dozens to hundreds of separate kelp gametophytes were associated with single host thalli. In many cases, the gametophytes developed conspicuous oogonia raised above the thallus surface on characteristic stalks. Presumed zygotes developed through typical embryonic stages into juvenile sporophytes. We argue that the endophytic habit plays an important role in the biology of kelp gametophytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050598
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of microbial methods as potential indicators of soil quality in historical agricultural fields (1995)
    Springer
    Biology and fertility of soils 19 (1995), S. 297-302 
    Details
    ISSN: 1432-0789
    Keywords: Phospholipids ; Microbial biomass ; Phosphatase ; Cropping systems ; Long-term experiments Prairie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In agricultural ecosystems that have had consistent cropping histories, standard microbial methods may be used to evaluate past and present practices. Our objective was to evaluate several microbial methods that best indicate cropping histories and soil quality on long-term plots. We selected soil microbial carbon (C), phospholipid analyses, direct counts of total fungal and bacterial biomass, and soil enzymes (phosphatases) to measure direct and indirect microbial activity on the Sanborn Field and Tucker Prairie. The Sanborn Field has been under various cropping and management practices since 1888 and the Tucker Prairie is an uncultivated site. Seven different plots were chosen on the Sanborn Field and random samples were taken in the summit area on the Tucker Prairie, which represented a reference site. Soil microbial biomass C, phospholipids, and enzyme activity were reflective of the cropping and management histories observed on the Sanborn Field. Enzymatic activity was highly correlated to soil organic matter. The direct counts of fungal and bacterial biomass showed that fungal populations dominated these soils, which may be attributed to soil pH. Soil microbial biomass C and enzyme assays seemed to be better potential indicators of cropping histories than the other methods tested in the long-term plots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336098
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of phosphate-solubilizing bacteria and vesicular-arbuscular mycorrhizae on tomato growth and soil microbial activity (1997)
    Springer
    Biology and fertility of soils 26 (1997), S. 79-87 
    Details
    ISSN: 1432-0789
    Keywords: Key words Organic acids ; Phosphate-solubilizing ; bacteria ; Vesicular-arbuscular mycorrhizae ; Glomus etunicatum ; Enterobacter agglomerans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The interaction of vesicular-arbuscular mycorrhizae (VAM) and phosphate-solubilizing bacteria (PSB) on plant growth, soil microbial activities, and the production of organic acids was studied in non-sterile soil containing hydroxyapatite and glucose. Glomus etunicatum (VAM), a fungus, and Enterobacter agglomerans, a bacterium able to solubilize insoluble phosphate, were used as inocula. Three treatments and a control were used: inoculation with E. agglomerans (treatment E), inoculation with G. etunicatum (treatment G), inoculation with E. agglomerans+G. etunicatum (treatment E+G) and the control (C). Inoculation with E, G, or E+G had increased plant growth by days 35, 55, and 75 compared with the control. Microbial biomass carbon (C) and alkaline phosphatase activity in the rhizosphere generally increased with time. Alkaline phosphatase activity was higher in treatments G and E+G compared with the control at 35 and 55 days. The highest acid phosphatase activity was observed in treatment E at 35 days; however, this markedly decreased with time. A significantly higher soluble phosphorus (P) concentration was observed in treatments E and E+G on day 55 compared with C. However, there was no significant difference in soluble P concentration in the rhizosphere between treatments with time. The P concentration was greatest in all treatments on day 55. The highest oxalic acid concentration was observed in the rhizosphere of the non-sterile soil in E+G on day 35. Total N and P uptake in plants from treatments E and G were higher compared with the control. However, the highest N and P uptake was observed in treatment E+G. This study suggests a synergistic interaction between E. agglomerans and G. etunicatum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050347
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  • 4
    Electronic Resource
    Electronic Resource
    Solubilization of hydroxyapatite by Enterobacter agglomerans and cloned Escherichia coli in culture medium (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 347-352 
    Details
    ISSN: 1432-0789
    Keywords: Key words Phosphate-solubilizing bacteria ; Hydroxyapatite ; Enterobacter agglomerans ; Organic acids ; Phosphate-solubilizing genes ; Rhizosphere ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphate-solubilizing bacteria (PSB) possessing the ability to solubilize insoluble inorganic phosphate were isolated from the rhizosphere soil of wheat. A laboratory study was conducted to investigate the solubilization of phosphate by a known PSB, Enterobacter agglomerans, and by a genetically manipulated bacterium, Escherichia coli. A second laboratory study investigated the release of P from E. agglomerans compared with known acids. For the first laboratory study, a cosmid (pHC79) library of phosphate-solubilizing gene(s) from E. agglomerans chromosome DNA was constructed in E. coli JM109. The clone JM109 (pKKY) showing phosphate solubilization properties was screened on standard medium containing hydroxyapatite (HY). The P concentration significantly increased at 5 and 10 days for JM109 (pKKY) compared with JM109 (pHC79), the control. Although the P concentration increased, there was no significant change in their pHs. Furthermore, an increase in colony-forming units (CFUs) was seen at 5 and 10 days for JM109 (pKKY) but not for JM109 (pHC79). Artificial acidification of the culture medium with HCl, citric acid, oxalic acid, and lactic acid was achieved by shaking for 48h. Acidification with these selected acids solubilized more HY than E. agglomerans growing for 42h at similar pHs. However, a high P concentration was measured in culture medium with E. agglomerans growing for 84h despite similar pHs. Our results suggest that acid production may play an important role in HY solubilization, but is not the sole reason for the increase in P concentration in culture medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050256
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  • 5
    Electronic Resource
    Electronic Resource
    Reaction of Müller cells after increased intraocular pressure in the rat retina (1998)
    Springer
    Experimental brain research 121 (1998), S. 419-424 
    Details
    ISSN: 1432-1106
    Keywords: Key words Glial fibrillary acidic protein ; Müller cell ; Increased intraocular pressure ; Retina ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Using light microscopy and immunocytochemistry, we investigated the morphological changes of retinal tissues and the reaction of Müller cells in the ischemic rat retina induced by increasing intraocular pressure. At early stages (from 1 h to 24 h after reperfusion), cells in the ganglion cell layer and in the inner nuclear layer showed some degenerative changes, but at later stages (from 72 h to 4 weeks) marked degenerative changes occurred in the outer nuclear layer (ONL). At 4 weeks after reperfusion, the ONL was reduced to 1 or 2 cell layers. Immunoreactivity for glial fibrillary acidic protein (GFAP) appeared in the endfeet and distal processes of Müller cells as of 1 h after reperfusion. GFAP immunoreactivity in Müller cells increased up to 2 weeks and then decreased at 4 weeks after reperfusion. Our findings suggest that Müller cells are involved in the pathophysiology of retinal ischemia through the expression of GFAP. The degree of GFAP expression in Müller cells closely correlated with that of the degeneration of retinal neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050476
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  • 6
    Electronic Resource
    Electronic Resource
    The change of magnetic properties in nanocrystalline Fe88Zr7B4Cu1 alloy by cooling rate : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5153-5155 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the effect of cooling rate, followed immediately after the isothermal annealing, on the magnetic properties of melt-spun Fe88Zr7B4Cu1 alloy. As the cooling rate is increased, the effective permeability, 2×104, improved by 50% on annealing at around 650 °C. The remanence ratio is also found to concomitantly decrease with the increasing cooling rate. The increase of permeability and decrease of remanence ratio are consistent with the expected suppression of the induced magnetic anisotropy. From an analysis of the transmission electron microscopy micrographs, and the x-ray diffraction spectral intensities, we find that the volume fraction of the amorphous matrix to that of the nanocrystallized magnetic entities to be about 20%, at which the permeability has the maximum value for this system. Scanning electron microscopy and antiferromagnetic investigations show a much smoother surface morphology with a finer grain distribution in the rapidly quenched sample. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361538
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  • 7
    Electronic Resource
    Electronic Resource
    Magnetic aftereffect in nanocrystalline Fe88Zr7B4Cu1 alloy : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6594-6596 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetic relaxation phenomenon was investigated by using the pulse method for an Fe88Zr7B4Cu1 alloy with nanoscale grain structure, which was prepared by melt quenching and a subsequent annealing. In order to know the relationship between the microstructure and the magnitude of magnetic aftereffect in the nanocrystalline state, annealing temperature dependence of volume fractions of crystalline bcc-Fe and residual amorphous phase was also measured. It was found that disaccommodation occurred in this nanocrystalline alloy, and the intensity of disaccommodation decreased as the fraction of the crystalline bcc-Fe phase increased. Moreover, the jumping field, defined by the magnetic field, at which initial magnetization curve rises abruptly decreased as the fraction of residual amorphous phase was reduced. From the observed results, the magnetic aftereffect was considered to result from the residual amorphous phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352575
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  • 8
    Electronic Resource
    Electronic Resource
    Magnetic properties behaviors in Fe88Zr7B4Cu1 nanocrystalline alloy prepared by different postanneal cooling rates : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6943-6945 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Effects of cooling rate after annealing on the soft magnetic properties were investigated for an Fe88Zr7B4Cu1 alloy with nanoscale grain structure, which was prepared by melt quenching. As the cooling rate increased, the effective permeability improved and the remanence ratio, which indicates the orientation of magnetic anisotropy (degree of pair ordering), decreased. The increase of permeability and decrease of remanence ratio were considered to result from the suppression of the induced magnetic anisotropy. Furthermore, the variation of disaccommodation behaviors with cooling rate was investigated in the Fe88Zr7B4Cu1 nanocrystalline alloy. It was found that the value of D (intensity of disaccommodation) was a little higher for the samples obtained from the high cooling rate than that for the low cooling rate. This result can be explained by domain structure stabilization due to local induced magnetic anisotropy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356789
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  • 9
    Electronic Resource
    Electronic Resource
    Theory of nonmonotonic double layers (1987)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 30 (1987), S. 3686-3694 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A simple graphic method of solving the Vlasov–Poisson system associated with nonlinear eigenvalue conditions for arbitrary potential structures is presented. A general analytic formulation for nonmonotonic double layers is presented and illustrated with some particular closed form solutions. This class of double layers satisfies the time stationary Vlasov–Poisson system while requiring a Sagdeev potential, which is a double-valued function of the physical potential. It follows that any distribution function having a density representation as any integer or noninteger power series of potential can never satisfy the nonmonotonic double-layer boundary conditions. A Korteweg–de Vries-like equation is found showing a relationship among the speed of the nonmonotonic double layer, its scale length, and its degree of asymmetry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866405
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  • 10
    Electronic Resource
    Electronic Resource
    Interlayer coupling field in spin valves with CoFe/Ru/CoFe/FeMn synthetic antiferromagnets (invited) (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 7612-7615 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Top synthetic spin valves with structure Ta/NiFe/CoFe/Cu/CoFe(P1)/Ru/CoFe(P2)/FeMn/Ta on Si (100) substrate with natural oxide were prepared by dc magnetron sputtering system. We have changed only the thickness of the free layer and the thickness difference (P1−P2) in the two ferromagnetic layers separated by Ru, and investigated the effect of magnetic film thickness on the interlayer coupling field in a spin valve with a synthetic antiferromagnet. As the free layer thickness decreased from 70 to 20 Å, the interlayer coupling field was increased due to the magnetostatic coupling (orange peel coupling). In the case of the thickness difference in the pinned layers, the interlayer coupling field agreed with the modified Néel model suggested in the top synthetic spin valve structures. However, in the case of tP1=tP2, and tP1=tP2+5 Å, it was found that the interlayer coupling field could not be explained by the modified Néel model. The deviation of the modified Néel model at the dip zone could be due to the large canting of the pinned layers, which depend on applied field and different thickness in synthetic antiferromagnetic structure. The dependence of Cu thickness on the interlayer coupling field was investigated and 10 Oe of the interlayer coupling field was obtained when the Cu thickness is 32 Å. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1361056
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