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  • Springer  (639)
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  • Articles  (639)
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  • 1
    Electronic Resource
    Electronic Resource
    The Effect of Al Implantation on the Thermal Oxidation of Stainless Steel in Aggressive Environments (2000)
    Springer
    Oxidation of metals 53 (2000), S. 303-323 
    Details
    ISSN: 1573-4889
    Keywords: ion implantation ; oxidation ; thermal ; stainless steel ; ion-beam analysis ; aluminum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract AISI-321 steel samples were implanted with Al ions (implantation-energy:40 keV; dose: 2×1017 ions/cm2). Thermal oxidationof the samples was performed at 450, 550, 600, and 650°C for periodsvarying from 1 to 6 days in air and in a corrosive CO2-containingenvironment. Nuclear Reaction Analysis (NRA) and Rutherford BackscatteringSpectrometry (RBS) were used to investigate the oxidized samples. Asignificant improvement of the oxidation resistance of the implantedmaterial in comparison to the nonimplanted material was observed. Thisespecially applies for samples oxidized at high temperatures. The aluminumdepth distribution determined by NRA [using the resonance at 992 keV of the27Al(p, γ )28Si nuclear reaction] and RBS,indicated no variation of the Al profile in the temperature region450–600°C, whereas at 650°C a slight Al diffusion wasobserved. Scanning electron microscopy (SEM–EDS) was applied to studythe surface morphology and the constitution of the oxide scale formed, aswell as to explain the influence of Al implantation on the oxidation behaviorof AISI-321 austenitic stainless steel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004541220830
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  • 2
    Electronic Resource
    Electronic Resource
    Oxidation Behavior of a Sputtered Ni–5Cr–5Al Nanocrystalline Coating (2000)
    Springer
    Oxidation of metals 53 (2000), S. 467-479 
    Details
    ISSN: 1573-4889
    Keywords: Ni–5Cr–5Al ; oxidation ; magnetron sputtering ; nanocrystalline coating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A NiO-forming Ni–5Cr–5Al (at.%) alloy has been developed anddeposited as a sputtered nanocrystalline coating. The oxide formation andoxidation behavior of this coating have been studied at 1000°C inair. The oxidation rate markedly decreased with time and the oxidationkinetics obeyed the fourth power law. Complex oxide scales, consisting ofNiO, NiAl2O4 and α-Al2O3,were formed during 200 hr oxidation. The outer oxide layer consisted of NiOand NiAl2O4 and an inner oxide layer ofα-Al2O3. The sputtered Ni–5Cr–5Alnanocrystalline coating showed good oxidation resistance due to theformation of an α-Al2O3 inner layer andexcellent adhesion of the complex oxide scales.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004628925414
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  • 3
    Electronic Resource
    Electronic Resource
    High-Temperature Oxidation of Ti0.3Al0.2N0.5 Thin Films Deposited on a Steel Substrate by Ion Plating (2000)
    Springer
    Oxidation of metals 53 (2000), S. 529-537 
    Details
    ISSN: 1573-4889
    Keywords: ion plating ; steel ; TiAlN coating ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract To improve the high-temperature oxidation resistance of STD61 steels used ashot dies or cutting tools, Ti0.3Al0.2N0.5films were deposited on STD61 steel substrates by arc-ion plating. Thedeposited film consisted of Ti3Al2N2 andTi2N phases. The oxidation characteristics were studied attemperatures ranging from 700 to 900°C in air. The deposited STD61steels displayed excellent oxidation resistance up to 800°C, butexhibited large weight gains and breakaway oxidation at 900°C. Theoxidation products were primarily Fe2O3, TiO, TiO2,and α-Al2O3, the relative amount of each oxidebeing dependent on the oxidation condition. Among various oxides, TiO2and α-Al2O3 were the major oxides at 800°Cfor at least up to 16 hr. However, at a higher temperature or a longeroxidation period, the significant outward diffusion of iron from thesubstrate resulted in the formation of iron oxides, together with otheroxides of Ti and Al.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004685010393
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of Nanocrystallization on the Oxidation Behavior of a Ni–8Cr–3.5Al Alloy (2000)
    Springer
    Oxidation of metals 54 (2000), S. 155-162 
    Details
    ISSN: 1573-4889
    Keywords: Ni–8Cr–3.5Al ; nanocrystallization ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Magnetron-sputter deposition was used to produce a Ni–8Cr–3.5Al(wt.%) nanocrystalline coating on substrates of the same alloy. Theoxidation behavior of the cast Ni–8Cr–3.5Al alloy and itssputtered coating were investigated at 1000°C in air. Complex,layered-oxide scales composed of Cr2O3 outer layer,mixed spinel NiAl2O4 and NiCr2O4middle layer, and α-Al2O3 inner layer were formedon the Ni–8Cr–3.5Al nanocrystalline coating during 200-hroxidation, whereas Cr2O3, with some NiCr2O4external layer with internal Al2O3, formed on the castalloy. Because of the formation of this α-Al2O3inner layer on the coating, the sputtered Ni–8Cr–3.5Al coatingshowed better oxidation resistance than the cast alloy. The effect ofnanocrystallization on oxide formation is discussed. It was indicated thatthe formation of this α-Al2O3 inner layer was closely related to therapid diffusion of Al through grain boundaries in the nanocrystallinecoating and the relatively high Cr content in Ni–8Cr–3.5Al.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004610931447
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of Chromium on the Oxidation Performance of β-FeAlCr Coatings (2000)
    Springer
    Oxidation of metals 54 (2000), S. 189-209 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; β-FeAlCr ; coatings ; magnetron sputter-deposition ; ridge-type oxide ; Al2O3 phase transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract β-FeAl coatings containing various Cr contents of 6.5–45 wt.%were produced with a closed-field, unbalanced magnetron sputter (CFUMS)deposition technique. Cyclic oxidation tests at 1100°C in air for100 1-hr cycles and isothermal exposures at 1000°C in pure O2 for100 hr were carried out with the coatings and an as-cast FeAlspecimen. All of the coatings showed good scale-spallation resistanceduring cyclic oxidation and the coating with 6.5 wt.% Cr exhibited thelowest oxidation rates in both cyclic and isothermal oxidationexposures. After oxidation, fine-grain ridge-type oxide scales formed onthe coatings, while the oxide scale formed on the cast FeAl showed alarge quantity of θ-Al2O3 blades and large interfacial voids on thebase–alloy surface. The transformation from θ to α-Al2O3was accelerated due to the presence of Cr in the coatings. The fasttransformation considerably reduced oxidation rates, suppressed fastoutward Al diffusion for the growth of a θ-Al2O3 scale, and preventedthe formation of interfacial voids that played a major role in causing thescale spallation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004669126961
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  • 6
    Electronic Resource
    Electronic Resource
    Metastable Chromium-Rich Oxide Formed during Plasma Spraying of High-Alloy Steel (2000)
    Springer
    Oxidation of metals 54 (2000), S. 549-558 
    Details
    ISSN: 1573-4889
    Keywords: plasma spraying ; chromium steel ; oxidation ; Fe–Cr spinel oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract During plasma spraying of metals in air, rapid-oxidation reactions occur, inmost cases. In oxidation products of Cr-rich steels, Fe–Cr spineloxide is often found as a dominant oxide phase. A thermodynamic analysisof a system composed of Fe–13%Cr alloy and water vapor or air showedthat the oxidation product in a wide range of high temperatures isFe3-wCrwO4 (w〉2). This tetragonallydistorted spinel oxide is not stable at room temperature. Water vapor andair were considered as limits of the gaseous-phase composition inatmospheric spraying by a water-stabilized plasma gun, where the compositionof the plasma plume is modified by air entrainment. The equilibriumcalculations enabled determination of the effects of temperature andgas-to-solid ratio on w. To show the existence of chromium-rich,tetragonally distorted spinel oxide experimentally, a typical productresulting from oxidation of 13%Cr–steel particles during their flightin the plasma plume was studied after rapid solidific ation. This was madepossible by trapping and quenching the flying particles in liquid nitrogenat a distance from the plasma-gun nozzle corresponding to thenozzle–substrate distance in conventional plasma spraying. The resultsobtained by X-ray diffraction, Mössbauer spectroscopy, and X-rayfluorescence analysis showed that this oxide, in which w≈2.4, constitutedthe dominant phase in the oxidation product.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004650904113
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  • 7
    Electronic Resource
    Electronic Resource
    A Contribution to the Mechanism of Formation of Humic Acids in Coal (2000)
    Springer
    Journal of materials synthesis and processing 8 (2000), S. 359-363 
    Details
    ISSN: 1573-4870
    Keywords: Mechanical activation ; brown coal ; electrophoretic mobility ; oxidation ; humic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents a study of the influence of mechanochemical activation of coal on the process of formation and degradation of humic acids. The increasing period of mechanical activation of coal causes an increase in hydrophility, electrophoretic mobility, and of electrokinetic potential of surface layers as a result of acidic carboxyl and phenolic OH groups. The effective activation requires a short period of grinding. The increased time of activation causes the secondary processes of grain agglomeration and degradation of humic acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011358831253
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  • 8
    Electronic Resource
    Electronic Resource
    Mixed Sulfidation/Carburization Attack on Several Heat-Resistant Alloys at 900°C (2000)
    Springer
    Oxidation of metals 53 (2000), S. 427-449 
    Details
    ISSN: 1573-4889
    Keywords: sulfidation ; carburization ; oxidation ; high-temperature corrosion ; commerical alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A sulfidation/carburization study of seven commercial heat-resistant alloyswas carried out at 900°C in a H2–25 vol.%CH4–14.8N2–4CO–0.6CO2–0.6H2Satmosphere. The equilibrium partial pressures for oxygen (O2) andsulfur (S2) were 1.1×10−22 and 4.1×10−8 atm,respectively, and the carbon activity for this system was unity. The time ofexposure was 500 hr. Relatively thick, mixed sulfide scales were formed onall of the alloys tested. In addition, internal carburization occurred inall of the alloys. Using metal loss (i.e., the reduction in samplethickness) plus internal attack (internal sulfidation plus internalcarburization) as a performance criterion, an alloy with a nominalcomposition of Ni–29 wt.% Co–28Cr–2.75Si performed thebest, showing 0.71 mm of attack. An alloy with a nominal composition ofFe–20 wt.% Ni–25Cr performed the worst, being totally consumedby the test (〉3.18 mm of attack). Alloys containing relatively highamounts of silicon (〉2.5%) showed a dramatic increase in theirsulfidation resistance compared to the other alloys containing lowersilicon contents. The amount of iron present within a given material playeda dominant role in the carburization attack that occurred, with as expected,high-iron alloys showing significant internal carburization because of ahigh solubility and diffusivity of carbon in the matrix. The importance ofthe various alloying elements with respect to sulfidation and carburizationresistance is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004698024506
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  • 9
    Electronic Resource
    Electronic Resource
    The Effects of Surface-Applied Oxide Films Containing Varying Amounts of Yttria, Chromia, or Alumina on the High-Temperature Oxidation Behavior of Chromia-Forming and Alumina-Forming Alloys (2000)
    Springer
    Oxidation of metals 53 (2000), S. 507-527 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; chromia ; alumina ; thin oxide films ; reactive element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In order to study the effects on oxidation behavior of changing thecomposition of oxide scales without changing the composition of theunderlying alloys, thin films, which contained various amounts of Y2O3,Cr2O3, or Al2O3 have been deposited on Fe–25%Cr andFe–25%Cr–5%Al prior to oxidation. There were major differencesbetween the (Fe–25%Cr)–(Cr2O3–Y2O3) and(Fe–25%Cr–5%Al)–(Al2O3–Y2O3) systems. A film ofCr2O3 on Fe–25%Cr reduced the oxidation rate and Cr2O3–Y2O3films reduced it still further. A film of Al2O3 onFe–25%Cr–5%Al reduced the rate considerably, butAl2O3–Y2O3 films exhibited rates that were greater than those forAl2O3 alone. A film, which consisted entirely of Y2O3, greatly decreasedthe oxidation rate of Fe–25%Cr, but increased that ofFe–25%Cr–5%Al. The changes in oxidation rate produced byY2O3 in the (Fe–25%Cr)–(Cr2O3–Y2O3) system weremuch greater than those produced in the(Fe–25%Cr–5%Al)–(Al2O3–Y2O3) system. As far asoxidation rate is concerned, the optimum amount of Y2O3 in the(Fe–25%Cr)–(Cr2O3–Y2O3) system was found to begreater than or equal to 40% and less than 100%; in theFe–25%Cr–5%Al)–(Al2O3–Y2O3) systemit was approximately 10%. In thermal-cycling tests, the resultsfor the (Fe–25%Cr)–(Cr2O3–Y2O3) system followedthe same pattern as that for the isothermal tests; a film of Y2O3reduced the oxidation rate and a film of Cr2O3–33%Y2O3reduced it still further.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004633026323
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  • 10
    Electronic Resource
    Electronic Resource
    The Effects of Molybdenum on the High-Temperature Oxidation Resistance of Thin Foils of Fe–20Cr–5Al at Very High Temperatures (2000)
    Springer
    Oxidation of metals 53 (2000), S. 561-576 
    Details
    ISSN: 1573-4889
    Keywords: Fe–Cr–Al alloy ; oxidation ; molybdenum ; breakaway oxidation ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thin foils of Fe–20Cr–5Al alloys are susceptible to breakawayoxidation once the aluminum content of the substrate has fallen below somecritical value. The combined addition of 0.1 wt.% lanthanum and 0, 1, or 2wt% molybdenum has a beneficial effect on the high-temperature oxidation ofsuch foils. Lanthanum has the well-known reactive-element effect on adhesionof the protective alumina scale, thereby increasing the time to onset ofbreakaway oxidation, while, for alloys containing molybdenum, breakawayoxide spreads relatively slowly over the specimen in comparison to alloysthat contain no molybdenum. In particular, molybdenum-containing alloys areable to develop a protective Cr2O3 layer at the breakawayoxide–substrate interface. Conversely, molybdenum-free alloys form aninternal-oxide zone in the substrate adjacent to this interface, rather thana Cr2O3 layer, so breakaway oxide spreads rapidly. A martensitic phase isobserved in the substrate adjacent to the breakaway oxide formed on Fe–20Cr–5Al–La specimens, which means that theα-phase has transferred to the γ -phase at the temperature ofthe oxidation test (1150°C). Conversely, α-phase is retained inthe molybdenum-containing alloy, even after breakaway takes place, sincemolybdenum, which is a strong ferrite former, is enriched in the alloyadjacent to areas of breakaway oxide. The diffusion rate of chromium isslower in the γ than in the α-phase so a continuouschromium-rich oxide layer, which is effective in inhibiting breakawayoxide from spreading, cannot be established at the breakawayoxide–substrate interface for the molybdenum-free alloys.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004689211302
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  • 11
    Electronic Resource
    Electronic Resource
    The Effect of Deformation Substructure on the High-Temperature Oxidation of Inconel 625 (2000)
    Springer
    Oxidation of metals 54 (2000), S. 63-71 
    Details
    ISSN: 1573-4889
    Keywords: microstructure ; Inconel 625 ; oxidation ; deformation substructure ; deformation twins ; energy-dispersive spectroscopy (EDS) ; internal oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The high-temperature, isothermal-oxidation behavior of a superalloy was studied in the as-rolled and deformed conditions. The microstructural changes occurring during the oxidation of samples were examined using optical, scanning electron microscopy (SEM), fine-probe EDS microanalysis, and X-ray diffraction techniques. The topography of the oxide layers formed in the as-rolled and cold-deformed specimens exposed at various temperatures and time intervals is also examined. The kinetics and microstructural results are presented for the comparative study of the structural changes occurring during high-temperature oxidation. It was found that a Cr2O3 external layer was adherent and uniform on the rolled specimens in comparison to the scattered and preferential oxide developed on the deformed specimens. The latter can be attributed to the concurrent dynamic changes occurring in the deformed substructure that subsequently lead to breaking and spallation of the oxide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004698528721
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  • 12
    Electronic Resource
    Electronic Resource
    Isothermal Oxidation of α2-Ti3Al (2000)
    Springer
    Oxidation of metals 54 (2000), S. 121-138 
    Details
    ISSN: 1573-4889
    Keywords: titanium aluminides ; oxidation ; oxygen-affected zone ; alpha case ; TEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The isothermal oxidation behavior of binary Ti–25 at.% Al was studiedat 1073, 1173, and 1273 K in air and oxygen with emphasis on themicrostructure of the subsurface zone underneath the external oxidescale. Thermogravimetric analysis, acoustic-emission (AE) analysis, lightmicroscopy, scanning electron microscopy (SEM), atomic force microscopy(AFM), and cross-sectional transmission electron microscopy (TEM) werecarried out. Three layers could be identified in the subsurface regionconsisting of an internal oxidation zone of α-Al2O3,and α-Ti, a ternary phase with the empirical formulaTi–21Al–15O (at.%), and an oxygen penetration zone consisting ofα2-Ti3Al(O).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004606830538
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  • 13
    Electronic Resource
    Electronic Resource
    Microstructural Evolution of Alumina Layers on an Al–Cu–Fe Quasicrystal during High-Temperature Oxidation (2000)
    Springer
    Oxidation of metals 54 (2000), S. 445-456 
    Details
    ISSN: 1573-4889
    Keywords: quasicrystals ; aluminides ; oxidation ; nodules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of a quasicrystal with the nominal compositionAl63Cu25Fe12 was studied around 800°Cin environmental and synthetic air by means of thermogravimetric analysis,electron microscopy, and analytical electron spectroscopy. In an earlyoxidation stage, γ-Al2O3 formed with an orientational relationship tothe quasicrystal. At the oxide–metal interface, γ-Al2O3transformed into large hexagonal shaped α-Al2O3grains. The change in surface morphology indicated that at theoxide–gas interface γ-Al2O3 continued togrow as Θ-Al2O3. Locally the metastable aluminalayer was transformed thoroughly into α-Al2O3,which then continued to grow with a nodular morphology. On top of the oxidenodules, several at.% of Cu2+ were detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004638501387
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  • 14
    Electronic Resource
    Electronic Resource
    Influence of Water Vapor and Flow Rate on the High-Temperature Oxidation of 304L; Effect of Chromium Oxide Hydroxide Evaporation (2000)
    Springer
    Oxidation of metals 54 (2000), S. 11-26 
    Details
    ISSN: 1573-4889
    Keywords: oxidation ; marginal chromia formers ; water vapor effect ; chromia evaporation ; breakaway corrosion ; flow-rate dependence ; 304L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of roman PH 2 O and flow rate on the oxidation of 304Lat 873 K in oxygen is reported. High concentrations of water vapor and highflow rates result in breakaway corrosion. The mass gain after 168 hrincreased by four to five times, compared to oxidation in dry O2. Inthe presence of H2O, the corrosion products consisted of arelatively thin (Cr,Fe)2O3 oxide plus large oxide islandsconsisting mainly of Fe2O3. A mechanism explaining theeffect of water vapor on marginal chromia formers is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004642310974
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  • 15
    Electronic Resource
    Electronic Resource
    An Ultralow Oxygen Partial Pressure-Controlling System and Its Application to Oxidation Studies (2000)
    Springer
    Oxidation of metals 54 (2000), S. 47-62 
    Details
    ISSN: 1573-4889
    Keywords: oxygen sensor ; oxygen pump ; solid-state electrolyte ; ZrO2 ; oxygen partial pressure ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An ultralow oxygen partial pressure-controlling system, based on solid-stateelectrochemical principles, has been developed. This system consists of anoxygen sensor and an oxygen pump and is controlled by a PC computer. Theoxygen sensor is used to measure the oxygen partial pressure in an enclosedsystem, while the oxygen pump is used to transport oxygen from the ambientair into the enclosed system or from the enclosed system to the ambientair. The operating conditions of this system have been studied. The resultsshowed that it can be used to establish a stable oxygen partial pressure inthe range of 10−18∼5×105 Pa (1×10−23∼5 atm)in the enclosed system. This system has been used to investigate theselective oxidation of the Cr and the oxide formation on the surface of aNi–Cr alloy under three different low oxygen partial pressures. Theoxide morphology was studied using atomic force microscopy (AFM). The resultsagreed well with those in the literature and also confirm the reliability of this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004646511882
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  • 16
    Electronic Resource
    Electronic Resource
    XRD Investigations of the Phosphorus Effect on the Oxidation of TiAl Alloys by High-Resolution Methods (2000)
    Springer
    Oxidation of metals 54 (2000), S. 317-337 
    Details
    ISSN: 1573-4889
    Keywords: TiAl ; oxidation ; phosphorus ; microdiffraction ; doping ; rutile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recently it has been found that very small amounts (a few 100 ppm) of Padded to γ -titanium aluminide can significantly alter the oxidationbehavior between 973 and 1273 K. The mechanism responsible for this changeis, however, still not clear. In the present study, phosphorus wasincorporated into the surface of TiAl (containing 50 at.% Al) by ionimplantation and oxidation tests were carried out at 1173 K inair. Improvement of oxidation resistance is only temporary up to 100 hr forphosphorus-implanted TiAl. After 100 hr, the oxidation rate increases andbreakaway oxidation follows. XRD and EPMA showed that the breakawayoxidation is connected with massive nitride formation. Two different modelsare proposed which can explain the effect of phosphorus additions on theoxidation kinetics of TiAl during the protective stage within the first100 hr. The breakaway effect can be explained by penetration of air to themetal–oxide interface zone because of microcrack formation in theoxide scale, which was experimentally proved by acoustic-emission analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004606513758
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  • 17
    Electronic Resource
    Electronic Resource
    Growth of Nodular Corrosion Products on Fe–Al Alloys in Various High-Temperature Gaseous Environments (2000)
    Springer
    Oxidation of metals 54 (2000), S. 339-371 
    Details
    ISSN: 1573-4889
    Keywords: Fe–Al alloys ; oxidation ; sulfidation ; nodular growth ; corrosion mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The mechanisms for nodular corrosion-product development were investigatedin various high-temperature gaseous environments. Fe–Al alloys, with5–20 wt.% Al, were exposed in both oxidizing and sulfidizing[p(S2)=10−4 atm, p(O2)=10−25 atm] atmospheres at 700°Cfor times up to 100 hr. The corrosion kinetics were monitored by theuse of a thermogravimetric balance and the morphological developmentthrough light-optical and scanning-electron microscopies,energy-dispersive spectroscopy, electron-probe microanalysis,and quantitative-image analysis. Under both conditions, theelimination of nodule formation was observed by increasing thealuminum content of the alloy, above 5 and 7.5 wt.% Al for oxidizingand sulfidizing environments, respectively, which promoted the growthand maintenance of a continuous surface scale of alumina. For thosealloys that were observed to develop nodular corrosion products, theirmorphological appearance was similar in nature regardless of thecorroding species. The nodules typically consisted of an outeriron-rich product, either sulfide or oxide, that was randomly dispersedacross an alumina scale. Samples from the oxidizing atmosphere displayeda single growth-rate time constant from the kinetics data, suggesting thatthe nodule growth mechanism was by the simultaneous or codevelopment oftwo different (Fe and Al) oxides from the onset of exposure. Measurementof nodule planar diameter and depth of penetration into the alloyindicated that growth occurred through diffusional processes. Kineticsdata from the development of sulfide nodules in the reducingenvironment revealed a different type of mechanism. Multiplegrowth-rate time constants were found due to the localized mechanicalfailure of an initially formed surface scale. At early times in thesulfidizing atmosphere, a low corrosion rate was recorded as acontinuous-alumina scale afforded protection from excessive productdevelopment. However, with the mechanical failure of the scale, sulfurwas able to attack the underlying substrate through a short-circuitdiffusion mechanism that resulted in rapid weight gains from nonprotective,iron sulfide growth. The sulfide morphologies observed were very complex ascontinued growth of the nodule did not solely depend upon the diffusingspecies through the previously formed corrosion products, but also,continued mechanical failure of the oxide scale. It is suggested that thedifference in development mechanisms between the two environments may liein the relative growth rates of the nonprotective, Fe-base corrosionproducts formed.
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    URL: http://dx.doi.org/10.1023/A:1004658530596
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    Air Oxidation of Two Nanophase Ni–Ag Alloys at 600–700°C (2000)
    Springer
    Oxidation of metals 54 (2000), S. 559-574 
    Details
    ISSN: 1573-4889
    Keywords: silver–nickel ; mechanical alloying ; oxidation ; two-phase alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Two nanophase Ni-base alloys containing 50 and 25 at.% Ag prepared by mechanical alloying, denoted Ni–50Ag and Ni–25Ag were oxidized in air at 600 and 700°C for 24 hr. Ni–50Ag underwent internal oxidation of nickel, associated with the formation of a continuous outermost layer of silver metal with scaling rates larger than those for pure nickel. On the contrary, Ni–25Ag formed a continuous NiO layer surmounted by a discontinuous silver layer and internal oxidation was suppressed. The oxidation rate of Ni–25Ag decreased with time much more rapidly than predicted by the parabolic rate law during the initial stage and eventually became parabolic, with rate constants much lower than those for the oxidation of pure nickel. These results are attributed to the two-phase nature and, particularly, to the very small grain size of the two alloys.
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    URL: http://dx.doi.org/10.1023/A:1004603020951
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  • 19
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    Influence of Atomizing Gases on the Oxide-Film Morphology and Thickness of Aluminum Powders (2000)
    Springer
    Oxidation of metals 53 (2000), S. 1-23 
    Details
    ISSN: 1573-4889
    Keywords: Aluminum ; SEM ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fine powders of aluminum were produced in a pilot-plant, inert-gas atomizerwith a “confined-design” nozzle, which operated vertically upward. Argonand helium at 1.85 MPa and nitrogen at 1.56 MPa were used as the atomizingagent. The morphology of the powder particles was examined by SEM. Powderswere sieved dry and wet. The Sauter mean diameter of the powders varied from20.70 to 10.25 μm depending on the atomizing gas. The distribution ofsizes was bimodal. The mean thickness of oxide on the surface of the powderwas calculated from the total oxygen contents of powder samples (determinedby a Leco analyzer). In addition, ESCA measurements and BET tests werecarried out for surface-oxide thickness and area measurements,respectively. The finest powder produced under helium incorporated thinnersurface-oxide layers than the coarser ones produced under argon andnitrogen. This was due to differences in physical properties (such asdensity, thermal conductivity) and flow properties (such as gasvelocity and relative velocity) of the atomizing gases used, i.e., helium,argon, and nitrogen. The oxide was very irregular in thickness in thecoarse-size range of the Al powders produced under argon and nitrogen. Thiswas presumably because of the high- and low-temperature oxidation ofaluminum droplets during the atomization and subsequent solidification andcooling periods leading to the rough surfaces observed with SEMinvestigation in the present work.
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    The Influence of the Alloy Microstructure on the Oxidation Behavior of Ti–46Al–1Cr–0.2Si Alloy (2000)
    Springer
    Oxidation of metals 53 (2000), S. 99-124 
    Details
    ISSN: 1573-4889
    Keywords: γ-TiAl-based intermetallic alloy ; oxidation ; microstructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of microstructure of the two-phase alloyTi–46Al–1Cr–0.2Si on the oxidation behavior in air between600 and 900°C was studied. The oxidation rate, type of scale, and scalespallation resistance were strongly affected by the type of microstructure,i.e., lamellar in as-cast material and duplex after extrusion at1300°C. The oxidation rate was affected by the size and distribution ofthe α2-Ti3Al phase, being faster for the extrudedmaterial with coarse α2-Ti3Al. The type of oxide scaledetermines the spalling resistance. Cast material developed a uniform scalethat spalled off after short exposure times at 800 and 900°C when a criticalthickness was reached. The extruded material presented a heterogeneous scalewith predominant thick regions formed on γ-TiAl-α2-Ti3Algrains and thin scale regions formed on γ-TiAl grains. Thistype of scale could permit an easier relaxation in the matrix of stressesgenerated by both thermal-expansion mismatch between scale and alloy andoxide growth, resulting in a higher spallation resistance.
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    URL: http://dx.doi.org/10.1023/A:1004534830767
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    The Effect of Si3N4 Additions on the Oxidation Resistance of TiAl Alloys (2000)
    Springer
    Oxidation of metals 54 (2000), S. 575-589 
    Details
    ISSN: 1573-4889
    Keywords: TiAl ; oxidation ; Si3N4 ; dispersed particles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation kinetics of TiAl alloys with and without 3 and 5 wt.%additions of Si3N4 particles were studied at 1173 and1273 K in 1 atm of air. The Si3N4 dispersions wereunstable in the matrix phase, so that some of them reacted with titaniumduring sintering to form Ti5Si3 and dissolvednitrogen. The oxide scale formed on TiAl–Si3N4alloys consisted of an outer TiO2, an intermediate(Al2O3+TiO2), and an inner(TiO2+Al2O3) mixed layers. The enhancedalumina-forming tendency, the presence of discrete SiO2 particlesbelow the outer TiO2 layer, and the improved scale adhesion bySi3N4 dispersions were attributable mainly to theincreased oxidation resistance compared to the Si3N4-freeTiAl alloys. Marker experiments showed that, for TiAl–Si3N4 alloys, the primary mode of scale growth was the outward diffusion oftitanium ions for the outer scale and the inward transport of oxygen ionsfor the inner scale.
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    URL: http://dx.doi.org/10.1023/A:1004655005022
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    Superlattices as Characterisation Tool for the Beginning of PS Formation (2000)
    Springer
    Journal of porous materials 7 (2000), S. 373-376 
    Details
    ISSN: 1573-4854
    Keywords: porous silicon ; superlattices ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Initial stage of porous silicon (PS) formation has been studied in an original way. Multilayer structures constituting of very thin layers of low porosity and thick layers of high porosity have been fabricated and characterised by optical tools and electron microscopy. The non linear behaviour resulting in a change in the dissolution velocity has been quantified by using a stack layer structure. Finally using thermal oxidation it has been shown that, due to the selective oxidation as a function of the porosity, porous silicon can be used to produce a Si/SiO2 like structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009618517652
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    Investigations of Activation Energy of Porous Silicon Oxidation Using Calorimetric Methods (2000)
    Springer
    Journal of porous materials 7 (2000), S. 335-338 
    Details
    ISSN: 1573-4854
    Keywords: porous silicon ; oxidation ; calorimeter ; desorption ; activation energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of porous silicon has been studied using differential scanning calorimeter. The oxidation was found to consist of two parts with different activation energies. This indicates the existence of two different reaction mechanism. The results from the hydrogen desorption measurements have been used to study the different oxidation behaviour of the n- and p+-type porous silicon. The results show that the dihydride structure dominates on the surface of the n-type porous silicon, contrary to p+-type porous silicon, where the monohydride is the major structure. Explanations of these features are discussed. Using the activation energy, the surface termination effects are investigated. The best improvement in the activation energy was observed in the sample, whose surface was partially stabilized by ammonium groups.
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    URL: http://dx.doi.org/10.1023/A:1009674702631
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    Study on the Si–Si Vibrational States of the Near Surface Region of Porous Silicon (2000)
    Springer
    Journal of porous materials 7 (2000), S. 339-343 
    Details
    ISSN: 1573-4854
    Keywords: porous silicon ; infrared spectroscopy ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The Si–Si vibrational states near the surface region of porous silicon has been characterized using Fourier Transform Infrared Spectroscopy (FTIR) due to its enlarged surface area. By means of anodic etch and oxidization experiments, two Si–Si vibration modes of porous silicon have been identified as near the surface regions and in the bulk, respectively. The intensity of absorption peak at 620 cm−1, which originates from the Si–Si bonds vibrations on the surface and near surface regions of porous silicon, is found to vary depending on the length of etch and degree of oxidation of porous silicon, which exists before etching and is recovered again after fully oxidation. The peak of 610 cm−1 doesn't change throughout the oxidation experiment, and to be assigned for Si–Si bond vibrations in the bulk. With an extra irradiation of Nd:Yag laser on the PS sample the Raman and FTIR spectra reveal a red shift. These results can give an interpretation to explain the different phenomenon of Si–Si vibrations of Raman and FTIR spectroscopy.
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    URL: http://dx.doi.org/10.1023/A:1009622601723
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    Electrical Control of the Reflectance of Porous Silicon Layers (2000)
    Springer
    Journal of porous materials 7 (2000), S. 205-208 
    Details
    ISSN: 1573-4854
    Keywords: porous silicon ; oxidation ; liquid crystal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper we demonstrate the filling of porous silicon (PS) layers with liquid crystals (LC's) in order to control the reflectance electrically. The preparation of PS and the choice of the right group of LC's will be presented. Especially an oxidation of PS is necessary so that the methods and parameters of oxidation will also be discussed. As a first result the increasing and decreasing of the thickness oscillations in the reflectance as a function of the applied voltage can be observed.
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    URL: http://dx.doi.org/10.1023/A:1009642922253
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    Optical Waveguides Fabricated from Oxidised Porous Silicon (2000)
    Springer
    Journal of porous materials 7 (2000), S. 243-246 
    Details
    ISSN: 1573-4854
    Keywords: porous silicon ; oxidation ; refractive index ; optical waveguide ; optical losses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Further results on the optical properties of oxidised porous silicon as a function of porosity and oxidation conditions are presented in this paper. The refractive index varies logarithmically with the oxidation time irrespective of the porosity of the sample and the oxidation temperature. Burried waveguides have been realised from as-prepared and oxidised porous silicon. Optical losses of 18 dB cm−1 at λ = 1.3 μm have been obtained after oxidation at 800°C for 35 min.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009659409958
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    Infrared Reflection Spectroscopy and Effective Medium Modeling of As-Anodized and Oxidized Porous Silicon Carbide (2000)
    Springer
    Journal of porous materials 7 (2000), S. 139-142 
    Details
    ISSN: 1573-4854
    Keywords: porous silicon carbide ; oxidation ; effective medium theory ; infrared reflectance (or IR) ; reststrahlen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We present a study of the infrared reflectance of porous silicon carbide (PSC) formed by the electrochemical dissolution of silicon carbide substrates of both 6H and 4H polytypes. The reflectance from n-PSC, both as-anodized and passivated, is reported for the first time. The passivation of PSC has been accomplished using a short thermal oxidation. Fourier transform infrared (FTIR) reflectance spectroscopy is employed ex situ after different stages of the thermal oxidation process. The characteristics of the reststrahlen band normally observed in bulk SiC are altered by anodization; further changes in the reflectance spectra occur following oxidation for different periods of time. An effective medium theory model that includes air, SiC and SiO2 as component materials is shown to characterize the observed changes in the reflectance spectra after different stages of PSC oxidation.
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    URL: http://dx.doi.org/10.1023/A:1009648518136
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    Successive Approximation Linear Quadratic Regulator for Estuarine Management Problem (2000)
    Springer
    Water resources management 14 (2000), S. 157-175 
    Details
    ISSN: 1573-1650
    Keywords: estuarine management ; fishery harvest ; freshwater inflow ; linear quadratic regulator ; salinity ; successive approximation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: Abstract A successive approximation linear quadratic regulator (SALQR)method is applied to solve estuarine management problems to determine the optimal amount of freshwater inflows into baysand estuaries to maximize fishery harvests. Fishery harvests areexpressed in regression equations as functions of freshwaterinflows. The optimization problem is posed as a discrete-timeoptimal control problem in which salinity represents the statevariable and freshwater inflow represents the control variable. A two-dimensional hydrodynamic-salinity transport model, HYD-SAL,is used as the transition to simulate the flow circulation andtemporal and spatial salinity pattern in an estuary system. Thebound constraints for the control and state variables areincorporated into the objective function using a penalty functionmethod to convert the problem into an unconstrained formulation. The SALQR method is applied to the Lavaca-Tres Palacios Estuaryin Texas and the results are compared with those of usingregression equations as the transition equations.
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    URL: http://dx.doi.org/10.1023/A:1026576129765
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    The effect of seawater flow and temperature on metamorphosis and postlarval development in great scallop (2000)
    Springer
    Aquaculture international 8 (2000), S. 513-530 
    Details
    ISSN: 1573-143X
    Keywords: great scallop (Pecten maximus) ; hatchery ; metamorphosis ; seawater flow ; spat development ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Variations in growth and survival of hatchery-reared post-metamorphicjuveniles of great scallop Pecten maximus prompted anexamination of settlement and postlarval development. The effects ofseawater flow and temperature on great scallop metamorphosis andpostlarvae were studied over a 4–5 week period. In allexperiments, and regardless of environmental conditions, great scallopmetamorphosed after a 2–3 week period with values of 35 to70%. Subsequently, spat numbers increased slightly. Spatmortality generally occurred from the third week onward and reachedlevels as high as 30% by the fifth week under standardconditions. At 20 °C, however, 60% mortality levels wererecorded. Differences in spat growth rate, ranging from 37 to 45 μmday−1, were noticed at different seawater flow ratesbut no clear tendency could be discerned. Temperature affected spatgrowth with an increase in size from 24 μm day−1 at15 °C to 35 μm day−1 at 18 °C. Conversely,growth was suppressed at 20 °C (14 μm day−1).For optimal metamorphosis and postlarval development in great scallop, aseawater flow of 4.3 L h−1 per sieve and a temperatureof 15 °C are recommended.
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    URL: http://dx.doi.org/10.1023/A:1009274707986
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    Effect of Boron on the Structure and Composition of Cobalt Silicides (2000)
    Springer
    Powder metallurgy and metal ceramics 39 (2000), S. 599-602 
    Details
    ISSN: 1573-9066
    Keywords: solid-phase reaction ; solubility ; temperature ; cobalt silicides ; boron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The system Co ― Si ― B is promising for development of new soft magnetic materials. We studied the effect of boron on the structure and composition of cobalt silicides during solid-phase reaction of powders of the starting components under a 3·10−3 Pa vacuum in the temperature range 200°C to 1300°C for boron content from 0.5 mass% to 7.7 mass% by differential thermal analysis, metallographic analysis, x-ray analysis, and electron-probe microanalysis. We established that boron is not soluble in cobalt silicides. Formation of ternary chemical compounds is typical for the Co ― Si ― B system.
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    URL: http://dx.doi.org/10.1023/A:1011384332153
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    Oxidation Resistance of Niobium Coated with Titanium Disilicide (2000)
    Springer
    Powder metallurgy and metal ceramics 39 (2000), S. 560-562 
    Details
    ISSN: 1573-9066
    Keywords: niobium ; coating ; silicon ; corrosion ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Coatings based on TiSi2 have been used to protect niobium alloys from corrosion at temperatures up to 1300°C. Kinetic oxidation curves are given for these coatings on niobium. The phase compositions of the coatings have been determined and also of the layers formed during oxidation. EPMA has been applied to the element distributions in the coating, from which it is concluded that the silicon is mobile. The high resistance to oxygen of coatings based on TiSi2 is due to the formation of films of TiO2 and SiO2 on them.
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    URL: http://dx.doi.org/10.1023/A:1011367928518
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    Root-shoot interactions in mineral nutrition (2000)
    Springer
    Plant and soil 226 (2000), S. 57-69 
    Details
    ISSN: 1573-5036
    Keywords: ABA ; K/Na selectivity ; nitrate reduction ; nitrogen ; phloem ; phosphate ; root-shoot interactions ; salinity ; xylem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In this paper four classes of co-operative root-shoot interations are addressed. (I) Nitrogen concentrations in the xylem sap originating from the root and in the phloem sap as exported from source leaves are much lower than those required for growth by apices and developing organs. Enrichment of xylem sap N is achieved by xylem to xylem (X-X) transfer, by which reduced N, but not nitrate, is abstracted from the xylem of leaf traces and loaded into xylem vessels serving the shoot apex. Nitrogen enrichment of phloem sap from source leaves is enacted by transfer of reduced N from xylem to phloem (X-P transfer). Quantitative data for the extent of the contribution of X-X and X-P transfer to the nutrition of young organs of Ricinus communis L. and for their change with time are presented. (II) Shoot and root cooperate in nitrate reduction and assimilation. The partitioning of this process between shoot and root is shifted towards the root under conditions of nitrate- and K-deficiency and under salt stress, while P deficiency shifts nitrate reduction almost totally to the shoot. All four changes in partitioning can be attributed to the need for cation-anion balance during xylem transport and the change in electrical charge occurring with nitrate reduction. (III) Even maintenance of the specificity of ion uptake by the root may – in addition to its need for energy – require a shoot-root interaction. This is shown to be needed in the case of the maintenance of K/Na selectivity under the highly adverse condition of salt stress and absence of K supply from the soil. (IV) Hormonal root to shoot interactions are required in the whole plant for sensing mineral imbalances in the soil. This is shown and addressed for conditions of salt stress and of P deficiency, both of which lead to a strong ABA signalling from root to shoot but result in different patterns of response in the shoot.
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    Leachate from a Waste Disposal Centre reduces the initiation of arbuscular mycorrhiza, and spread of hyphae in soil (2000)
    Springer
    Plant and soil 227 (2000), S. 35-45 
    Details
    ISSN: 1573-5036
    Keywords: ammonia ; ammonium ; arbuscular mycorrhiza ; landfill ; leachate ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Irrigating arbuscular mycorrhizal plants with leachate from a waste disposal centre was examined in a set of experiments. Application of leachate at half the average concentration found in the field or higher reduced the growth of the host plant, the initiation of mycorrhizal colonisation, and hyphal growth of the mycorrhizal fungus Glomus pellucidum through the soil. Causes of these reductions are complex and interrelated, and associated with the electrical conductivity of the solution, toxicity of specific ions, in particular NH4 +, NH3 and HCO3 −, and changes in the pH causing shifts in the equilibria of the soil solution.
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    The influence of temperature and nitrogen source on growth and nitrogen uptake of two polar-desert species, Saxifraga caespitosa and Cerastium alpinum (2000)
    Springer
    Plant and soil 227 (2000), S. 139-148 
    Details
    ISSN: 1573-5036
    Keywords: Arctic ; Cerastium alpinum ; nitrogen source ; nitrogen-uptake ; organic N ; polar-desert plants ; Saxifraga caespitosa ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Polar-desert plants experience low average air temperatures during their short growing season (4–8 °C mean July temperature). In addition, low availability of inorganic nitrogen in the soil may also limit plant growth. Our goals were to elucidate which N sources can be acquired by polar-desert plants, and how growth and N-uptake are affected by low growth temperatures. We compared rates of N-uptake and increases in mass and leaf area of two polar-desert species (Cerastium alpinum L. and Saxifraga caespitosa L.) over a period of 3 weeks when grown at two temperatures (6 °C vs. 15 °C) and supplied with either glycine, NH4 + or NO3 −. At 15 °C, plants at least doubled their leaf area, whereas there was no change in leaf area at 6 °C. Measured mean N-uptake rates varied between 0.5 nmol g−1 root DM s−1 on glycine at 15 °C and 7.5 nmol g−1 root DM s−1 on NH4 + at 15 °C. Uptake rates based upon increases in mass and tissue N concentrations showed that plants had a lower N-uptake rate at 6 °C, regardless of N source or species. We conclude that these polar-desert plants can use all three N sources to increase their leaf area and support flowering when grown at 15 °C. Based upon short-term (8 h) uptake experiments, we also conclude that the short-term capacity to take up inorganic or organic N is not reduced by low temperature (6 °C). However, net N-uptake integrated over a three-week period is severely reduced at 6 °C.
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    URL: http://dx.doi.org/10.1023/A:1026528830228
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    Leaf K/Na ratio predicts salinity induced yield loss in irrigated rice (2000)
    Springer
    Euphytica 113 (2000), S. 109-118 
    Details
    ISSN: 1573-5060
    Keywords: grain yield ; leaf K/Na ratio ; Oryza sativa ; salinity ; screening tools ; yield reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Salinity is a major constraint to irrigated rice production, particularly in semi-arid and arid climates. Irrigated rice is a well suited crop to controlling and even decreasing soil salinity, but rice is a salt-susceptible crop and yield losses due to salinity can be substantial. The objective of this study was to develop a highly predictive screening tool for the vegetative growth stage of rice to estimate salinity-induced yield losses. Twenty-one rice genotypes were grown over seven seasons in a field trials in Ndiaye, Senegal, between 1991 and 1995 and were subjected to irrigation with moderately saline water (3.5 mS cm-1, electrical conductivity) or irrigation with fresh water. Potassium/sodium ratios of the youngest three leaves (K/NaLeaves) were determined by flame photometry at the late vegetative stage. Grain yield was determined at maturity. All cultivars showed strong log-linear correlations between K/NaLeaves and grain yield, but intercept and slope of those correlations differed between seasons for a given genotype and between genotypes. The K/NaLeaves under salinity was related to grain yield under salinity relative to freshwater controls. There was a highly significant correlation (p 〈 0.001) between K/NaLeaves and salinity-induced grain yield reduction: the most susceptible cultivars had lowest K/NaLeaves and the strongest yield reductions. Although there were major differences in the effects of salinity on crops in both the hot dry season (HDS) and the wet season, the correlation was equally significant across cropping seasons. The earliest possible time to establish the relationship between K/NaLeaves under salinity and grain yield reduction due to salinity was investigated in an additional trial in the HDS 1998. About 60 days after sowing, salinity-induced yield loss could be predicted through K/NaLeaves with a high degree of confidence (p 〈 0.01). A screening system for salinity resistance of rice, particularly in arid and semi-arid climates, is proposed based on the correlation between K/NaLeaves under salinity and salinity-induced yield losses.
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    URL: http://dx.doi.org/10.1023/A:1003981313160
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    Modification of the response of saline stressed tomato plants by the correction of cation disorders (2000)
    Springer
    Plant growth regulation 30 (2000), S. 37-47 
    Details
    ISSN: 1573-5087
    Keywords: glucose phosphate synthase ; invertase ; mineral nutrition ; salinity ; water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The interactions between NaCl and other major nutrients have been generally observed in plants. Decreases of nutrient uptake under saline conditions normally appear in tomato plants grown under saline conditions. In this work, the effect of increased external Ca, K and Mg concentrations under saline conditions has been investigated. Tomato plants (Lycopersicon esculentum, Mill) were grown in a greenhouse, in 120 L capacity containers, filled with continuously aerated Hoagland nutrient solution. Treatments were added to observe the combined effect of two NaCl levels (30 and 60 mM) and three levels of Ca, K and Mg (in mM ratios of 4:6:1, 7:9:2 and 10:12:3; treatments C1, C2 and C3 respectively) on growth, fruit yield and water relations. Saline treatments decreased the growth, which was partly restored with the C2 treatment and totally with the C3 treatment. A good association was observed between the electric conductivity of the medium and the water or osmotic potential of the leaves, independent of the type of treatment (salinity or cation ratio). Salinity at 30 and 60 mM NaCl reduced the fruit yield compared with that obtained at 0 mM NaCl. However, there was an increase, as a consequence of the application of treatments C2 and C3, in each saline treatment. At a high salinity level (60 mM), the ratios Na/K, Na/Ca and Na/Mg in young leaves decreased as a consequence of cation treatments. Higher concentrations of sugars in leaves and fruits were obtained after increasing the salinity and cation concentrations. Also, sucrose phosphate synthase activity in leaves and fruits was increased after the treatments, but there was no measurable invertase activity in fruits. Therefore, the concentrations of Ca, K and Mg in the nutrient solution could be important factors in the hydroponic culture of tomato grown under saline conditions.
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    Use of Electrical Conductivity Instead of Soluble Salts for Soil Salinity Monitoring in Central Asia (2000)
    Springer
    Irrigation and drainage systems 14 (2000), S. 199-206 
    Details
    ISSN: 1573-0654
    Keywords: salinity ; electrical conductivity ; laboratory ; data ; Central Asia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The USSR classifications of soil salinity used in Central Asiawas based on laboratory measurement of the total dissolved(toxic) salts or the chloride ion concentration in the soil waterextracts (soil:water = 1:5). Current practices, however, startto differ between the republics because of different levels ofacceptance of international literature. This change in practiceis triggered partly by the cost of the laboratory measurements.The use of different methods next to each other affects thereliability of information on salinity. This paper promotes theused of the UC of a 1:1 soil-water suspension was found to givethe best fit to the soil extract with leaching of calcium andsulfate ions. The cost of data collection is significantly lowerthan that of the 1:5 extract.
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    Revisiting the relationship between common weather variables and loblolly–shortleaf pine seed crops in natural stands (2000)
    Springer
    New forests 19 (2000), S. 187-204 
    Details
    ISSN: 1573-5095
    Keywords: Coastal Plain sites ; Pinus echinata Mill. ; P. taeda L. ; precipitation ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seed production was monitored during24 years using seed-collection traps inloblolly–shortleaf pine (Pinus taeda L.–P.echinata Mill.) stands located in southeast Arkansas,north-central Louisiana, and southwest Mississippi onthe southeastern Coastal Plain, USA. Sound seedproduction was correlated with mean monthlyprecipitation and temperature from National Oceanicand Atmospheric Administration weather stationslocated near the seed-collection areas to determinethe potential of weather factors in forecasting pineseed crops. Correlations were restricted to threecritical periods in the pine reproductive cycle –strobili primordia differentiation, pollination, andfertilization. The most important (P ≤ 0.05)variables correlated with pine seed production for combined locations were cumulative precipitation (r = +0.60) during July, August, and September at 27 to 25 months before seed dispersal and mean temperature (r = −0.45) in August at 26 months before seed dispersal. Because multiple environmental factors can negatively impact pine seed development during the two yearsfollowing strobili primordia differentiation,seed-production forecasts based on weather variablesshould be verified by on-site cone counts during thesummer preceding autumn seed dispersal.
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    URL: http://dx.doi.org/10.1023/A:1006624907975
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    Salinity increases CO2 assimilation but reduces growth in field-grown, irrigated rice (2000)
    Springer
    Plant and soil 218 (2000), S. 1-10 
    Details
    ISSN: 1573-5036
    Keywords: dry matter reduction ; leaf chlorophyll content ; leaf sodium uptake ; Oryza sativa ; photosynthesis ; salinity ; season effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Salinity is a major yield-reducing factor in coastal and arid, irrigated rice production systems. Salt tolerance is a major breeding objective. Three rice cultivars with different levels of salt tolerance were studied in the field for growth, sodium uptake, leaf chlorophyll content, specific leaf area (SLA), sodium concentration and leaf CO2 exchange rates (CER) at photosynthetic active radiation (PAR)-saturation. Plants were grown in Ndiaye, Senegal, at a research station of the West Africa Rice Development Association (WARDA), during the hot dry season (HDS) and the wet season (WS) 1994 under irrigation with fresh or saline water (flood water electrical conductivity = 3.5 mS cm-1). Relative leaf chlorophyll content (SPAD method) and root, stem, leaf blade and panicle dry weight were measured at weekly intervals throughout both seasons. Specific leaf area was measured on eight dates, and CER and leaf sodium content were measured at mid-season on the first (topmost) and second leaf. Salinity reduced yields to nearly zero and dry-matter accumulation by 90% for the susceptible cultivar in the HDS, but increased leaf chlorophyll content and CER at PAR- saturation. The increase in CER, which was also observed in the other cultivars and seasons, was explained by a combination of two hypotheses: leaf chlorophyll content was limited by the available N resources in controls, but not in salt-stressed plants; and the sodium concentrations were not high enough to cause early leaf senescence and chlorophyll degradation. The growth reductions were attributed to loss of assimilates (mechanisms unknown) that must have occurred after export from the sites of assimilation. The apparent, recurrent losses of assimilates, which were between 8% and 49% according to simulation with the crop model for potential yields in irrigated rice, ORYZA S, might be partly due to root decomposition and exudation. Possibly more importantly, energy-consuming processes, such as osmoregulation, interception of sodium and potassium from the transpiration stream in leaf sheaths and their subsequent storage, drained the assimilate supply.
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    URL: http://dx.doi.org/10.1023/A:1014953504021
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    Leaf development, transpiration and ion uptake and distribution in sugarcane cultivars grown under salinity (2000)
    Springer
    Plant and soil 218 (2000), S. 59-69 
    Details
    ISSN: 1573-5036
    Keywords: growth ; ion-uptake ; salinity ; salt tolerance ; sugarcane ; transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of salinity on leaf growth, initiation and senescence, on transpiration rates, on leaf water potential and on uptake and distribution of several ions were studied in two sugarcane cultivars differing in salinity sensitivity. Plants, growing in a growing mixture in pots, were exposed to salinized irrigation water for 68 days, starting 60 days after planting. EC values of the irrigation water were 1.0, 2.0, 4.0, 8.0 and 12 dS/m, obtained by using a mixture of NaCl and CaCl2. Plants were also grown in nutrient solution and were at a similar age when exposed to a salinity level of 3 dS/m for 30 days followed by 6.0 dS/m for an additional 30 days. Two Na:Ca ratios of 18:1 and 1:2 were used for salinization of the nutrient solution. Both leaf dry weight and area decreased with increasing salinity, but in the more salinity tolerant cultivar H69-8235, the decrease was moderate. Salinity hardly reduced average area per leaf in H69-8235, while the number of leaves declined sharply. This decline was caused by enhanced senescence of mature leaves and not by a decreased rate of leaf initiation. In the more sensitive cultivar, H65-7052, leaf area and initiation of new leaves were sharply reduced by salinity while leaf senescence was less affected. Leaf water potential decreased during the early stages of salinity exposure, and the reduction in water potential was larger in H69-8235. Salinity also decreased the rate of transpiration rate but to a lesser extent than leaf development and growth. The accumulation of Cl and Na in the TVD (top visible dewlap) leaf of the tolerant cultivar H69-8235 was greater than in the sensitive cultivar H65-7052. The concentration of Cl in the TVD leaf was more than 10 times that of Na in both cultivars. The concentration of both ions, but not of K, increased during the early stages of salinity exposure and then remained constant. A gradient in concentration of Cl and Na over the plant was found in both cultivars at all salinity levels, and was steepest between the TVD and younger leaves. No specific Na effect on leaf growth or transpiration could be detected. The accumulation of Cl and Na but not of K occurred primarily in the roots rather than in the leaves and stalks.
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    Phenotypic characteristics of root-nodulating bacteria isolated from Acacia spp. grown in Libya (2000)
    Springer
    Plant and soil 224 (2000), S. 171-183 
    Details
    ISSN: 1573-5036
    Keywords: Acacia ; Libya ; root-nodulating bacteria ; salinity ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thirty isolates of root-nodulating bacteria obtained from Acacia cyanophylla, A. karroo, A. cyclops, A. tortilis (subsp.raddiana), Faidherbia albida and Acacia sp., grown in different regions of Libya, were studied by performing numerical analysis of 104 characteristics. Three fast- and one slow-growing reference strains from herbaceous and woody legumes were included. Five distinct clusters were formed. The fast-growing reference strains were separated from the isolates whereas the slow-growing was included in cluster 4. With the exception of one cluster, the majority of clusters were formed regardless of the host plant or site of origin. Based on plant tests, generation times, acid production and carbon utilization the isolates were diverse (fast and slow-growing isolates). Like slow-growing isolates, most of the fast-growing isolates appeared to be non-specific, nodulated many species from the same genus notably F. albida, known to nodulate only with slow-growing strains. Most clusters grew at temperatures 35 °C and 37 °C; some grew at temperatures above 40 °C. The majority of isolates grew at acid and alkaline pH and only one isolate grew below pH 4. Most isolates were able to utilize many amino acids as nitrogen sources and to reduce nitrate. Urea was hydrolysed by all clusters. Monosaccharides and polyols were used by slow and fast-growing isolates as the only carbon sources whereas assimilation of disaccharides varied: Some isolates, like slow-growing isolates, failed to utilize these carbon sources. Most isolates were unable to utilize polysaccharides. Regarding tolerance to NaCl on agar medium, the majority of isolates were unable to grow at a concentration of 2% NaCl, but some were highly resistant and there was one isolate which grew at 8% NaCl. Most isolates were resistant to heavy metals and to antibiotics.
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    Oxidized Porous Silicon: From Dielectric Isolation to Integrated Optical Waveguides (2000)
    Springer
    Journal of porous materials 7 (2000), S. 215-222 
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    ISSN: 1573-4854
    Keywords: oxidized porous silicon ; anodization ; oxidation ; dielectric isolation ; optical waveguide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A brief review of 20-years research of formation, processing and utilizing of oxidized porous silicon (OPS) is presented. Electrolytes to form porous silicon (PS) layers, special features of PS chemical cleaning and thermal oxidation are discussed. OPS application for dielectric isolation of components of bipolar ICs and for the formation of silicon-on-insulator structures has been demonstrated. Although these OPS-based techniques have found limited current commercial use, experience gained is applicable to the fabrication of optoelectronic devices. Specifically, integrated optical waveguides based on OPS have been developed.
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    URL: http://dx.doi.org/10.1023/A:1009647007232
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    Dynamics of the Subsurface Temperature Field Caused by Mining-Related Groundwater Management (2000)
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    Studia geophysica et geodaetica 44 (2000), S. 442-459 
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    ISSN: 1573-1626
    Keywords: temperature ; groundwater ; sedimentary basin ; exploitation ; transient effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract The subsurface temperature field was studied on a set of 46 borehole logs measured in the vicinity of uranium deposits in the Bohemian Cretaceous Basin. Vertical variations of the steady state temperature and the temperature gradient are governed by thermal conductivity which strongly varies in dependence on lithology. Large departures from undisturbed temperature detected in many holes are associated with uranium mining. A positive anomaly is observed in leaching fields where large amounts of acid are injected into the uranium-bearing Cenomanian. A negative anomaly is linked to the operation of hydraulic barriers which enclose the mining area and helps to contain pollution by pumping clean water into the Cenomanian aquifer. The spatial distribution of the observed temperature anomalies helps to map the migration of the fluids used in both processes. The temperature disturbance is propagated from the Cenomanian aquifer up through overlying impermeable sediments. The good fit of transient conductive models to the measured temperatures rules out heat advection and hence upward water flow towards and contamination of the upper Middle Turonian aquifer in the vicinity of the holes studied.
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    Oxidation of Porous Silicon in Dry and Wet Environments under Mild Temperature Conditions (2000)
    Springer
    Journal of porous materials 7 (2000), S. 63-66 
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    ISSN: 1573-4854
    Keywords: porous silicon ; oxidation ; IR spectroscopy ; vibrational analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxidation behavior of porous silicon under various environments of dry and wet air, and solution with and without appropriate oxidant at mild temperatures has been investigated. The progress of oxidation was followed by infrared spectroscopy. The presence of water vapor greatly accelerates the oxidation rate in comparison with the rate in dry air. The oxidized states are clarified with the help of oxidation experiments of partially hydrogen-desorbed porous silicon, which does not contain SiH2 and SiH3 as the hydride species. An oxidation mechanism is proposed to explain that oxidation is accelerated in the presence of water vapor and at the partially hydrogen-desorbed porous silicon. Further, oxidation behavior of porous silicon in solution containing appropriate oxidant is also investigated. The rate is very rapid and the oxidation does not produce the back-bond oxidized state of OySiHx in contrast to the oxidation in air.
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    Magnéli phases of anion-deficient rutile as lubricious oxides. Part I. Tribological behavior of single-crystal and polycrystalline rutile (Ti n O2n−1) (2000)
    Springer
    Tribology letters 8 (2000), S. 65-78 
    Details
    ISSN: 1573-2711
    Keywords: solid lubricants ; lubricious oxides ; TiO2 ; rutile ; oxygen stoichiometry ; Magnéli phases ; tribometry ; friction ; wear ; shear strength ; temperature ; atmosphere ; extreme environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In part I of this paper series, wide temperature range SEM-tribometric results generated in vacuum and various partial pressures of oxygen are combined with relevant literature data to examine a hypothesis correlating the oxygen stoichiometry of the Ti n O2n−1 Magnéli phases of the rutile polymorph of titania with their tribological behavior. Single-crystal and polycrystalline rutile specimens of narrow stoichiometry ranges were sliding against α-SiC and themselves. The surface shear strength changes were determined as a function of the thermal–atmospheric test environment, and the shear strength values were estimated by the coefficients of friction, the real area of contact and the published yield strength of rutile. The data appear to be sufficient and sufficiently reliable to confirm the accuracy of the hypothesis. The tendency of the rutile stoichiometry (ergo the friction) to shift as a function of temperature and partial pressure of oxygen causes this material to be thermo-oxidatively unstable for tribological applications in extreme environments. In part II, a study is described to formulate oxidatively more stable Magnéli phases by Cu-doping, and test the new materials by SEM tribometry using a procedure used for pure rutile here in part I. By employing this doping methodology similar to creating high-temperature superconductive oxides in part II, some feasibility of producing oxidatively stable, lubricious oxides with acceptably low wear rates is indicated.
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    FTIR spectroscopy and nanotribological comparative studies: influence of the adsorbed water layers on the tribological behaviour (2000)
    Springer
    Tribology letters 9 (2000), S. 111-117 
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    ISSN: 1573-2711
    Keywords: AFM ; force ; friction ; adhesion ; molecular water layer ; temperature ; capillary forces ; PMIRRAS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Under ambient conditions, a water film is always present on a silica substrate and generates additional capillary forces between the nanotip and the studied surface. In the present paper, we report AFM measurements of pull-off and friction forces as a function of the temperature and a comparative FTIR spectroscopy study. The AFM results show a net decrease of the forces as the temperature increases, while the IR spectroscopy indicates that the liquid film is removed at high temperature. Consequently, we deduce that a liquid neck is created between the tip and the surface and that the forces measured are mostly capillary forces. The present work shows that temperature studies with AFM can be a useful way to probe the influence of the capillary force in turn to characterize surface properties.
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    Magnéli phases of anion-deficient rutile as lubricious oxides. Part II. Tribological behavior of Cu-doped polycrystalline rutile (Ti n O2n−1) (2000)
    Springer
    Tribology letters 8 (2000), S. 79-96 
    Details
    ISSN: 1573-2711
    Keywords: solid lubricants ; lubricious oxides ; TiO2 ; rutile ; oxygen stoichiometry ; Magnéli phases ; tribometry ; friction ; wear ; shear strength ; temperature ; atmosphere ; extreme environment ; molecular engineering ; cation doping ; aliovalency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract As a follow-up to the work described in part I of this paper series, a preliminary study was conducted with polycrystalline rutile TiO−x to render its friction and wear performance independent of the environment. The main goal was to confine the most tribologically desirable oxygen stoichiometries of the crystallographic shear-induced Magnéli phases (CSMP) of rutile by doping with cations similar in size and polarizability to the Ti4+, but with lower valences. The resultant chemical expulsion of oxygen from the rutile lattice was intended to generate CSMP free of friction and wear variations caused by changes in the thermal–atmospheric environment. Copper, iron, cobalt and nickel ions were tried as dopants introduced as their stable oxides via a simple ball-milling, hot-pressing and annealing procedure, but only a (Ti + Cu)O1.80 model blend resulted in a desired reaction. A portion of the copper entered the lattice to form a new titanium–copper CSMP, resembling the well-known V3Ti6O17 catalyst equivalent to an undoped rutile CSMP with an O/Ti ratio of 1.89. Although the shear behavior of this new, wear-resistant compound was in accordance with predictions, its friction is higher and more variable than desired for a wide environmental regime lubricant. The preparation technique was only sufficient to demonstrate that oxygen vacancy-induced creation of low-friction CSMP may be possible by doping; it does not appear to be useful for formulating practical, rutile-based lubricious oxides.
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    Characteristics of Pestalotiopsis Associated with Hardy Ornamental Plants in the UK (2000)
    Springer
    European journal of plant pathology 106 (2000), S. 77-85 
    Details
    ISSN: 1573-8469
    Keywords: Pestalotiopsis sydowiana ; morphology ; pathogenicity ; ericaceous plants ; conifers ; temperature ; pH ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pestalotiopsis isolates obtained from the foliage, stem-base and roots of hardy ornamentals grown on commercial nurseries in the UK were identified and characterised according to pathogenicity and colony morphology. All 18 isolates were identified as Pestalotiopsis sydowiana on the basis of conidia morphology, and confirmation of identification was made by experts at CABI Bioscience. Isolates were pathogenic on the host from which originally isolated. Typical symptoms included foliar browning of foliage and stems, and the presence of black or greenish-black acervuli on diseased tissue. Isolates were not host specific and infected other species of hardy ornamentals. Three colony types on potato dextrose agar were distinguished according to colour and production of acervuli by individual isolates. Three selected isolates of P. sydowiana were characterised by examining the effects of growth media, temperature, pH, and water potential on hyphal extension. Isolates grew well on commonly used growth media, including PDA, Sabouraud dextrose agar (SDA), V8 juice agar (V8), malt extract agar (MEA) and Czapek Dox agar (CDA). The optimum temperature for growth on PDA was in the range 20–25°C, with little or no growth occurring below 5°C or above 30°C. Hyphal extension occurred over a pH range between 2.6–8.6, with optimum values occurring at pH 5.5. In general, decreases in osmotic and matric potential caused a reduction in growth. Hyphal extension on media adjusted osmotically as NaCl ceased between −9.9 and −10.5 MPa. Isolates were more tolerant of osmotic than matric potential, with no growth occurring at −6.5 MPa on media adjusted with polyethylene glycol.
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    The effect of temperature on development and fecundityof Scymnus levaillanti (2000)
    Springer
    BioControl 45 (2000), S. 453-462 
    Details
    ISSN: 1573-8248
    Keywords: development ; fecundity ; functional response ; reproductive numerical response ; temperature ; Coccinellidae ; Aphis gossypii ; Scymnus levaillanti
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Development and fecundity of Scymnus levaillanti(Mulsant) were recorded at fiveconstant temperatures ranging from 15 to 35 ± 1 °C in 5 °C increments, 60 ± 5% RHand 16 h of artificial light (5000 Lux). Developmentaltime (egg to adult) of S. levaillantisignificantly decreased with increasing temperatures,ranging from 63.9 days at 15 °C to 11.1 days at35 °C. Development from egg to adult required305.2 DD above a developmental threshold estimated as11.7 °C. Oviposition periods lasted 86.5, 76.1,47.2, and 31.5 days at 20, 25, 30 and 35 °C,respectively. No eggs were deposited at 15 °C.Higher temperatures resulted in shorter generationtimes (TO) and in decreased net reproductiverates (RO) of the coccinellid. S.levaillanti kept at 30 °C produced 0.151females/female/day, the highest per capita rate ofpopulation growth (rm). The `functional response'of larvae and adults of S. levaillanti matcheswell that described by Holling (1959) as Type 2.Daily number of eggs deposited by females increased toa plateau with increasing prey density. Resultsobtained here provide information about the biology ofS. levaillanti, and its feeding capacityindicates that it may act as an important control agent.
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    Susceptibility of the legume flower thrips to Metarhizium anisopliae on different varieties of cowpea (2000)
    Springer
    BioControl 45 (2000), S. 79-95 
    Details
    ISSN: 1573-8248
    Keywords: anti-fungal substances ; control ; host plant resistance ; Megalurothrips sjostedti ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The susceptibility of Megalurothrips sjostedtito Metarhizium anisopliae when reared on susceptible, tolerant, and moderately resistant varieties of cowpea at different constant temperatures was evaluated in the laboratory. Insects were exposed either to direct spray of the conidia or to fungus-treated floral tissues. Mortality was significantly higher on the moderately resistant variety at all temperatures compared to the susceptible and tolerant varieties. Correspondingly, lethal time and lethal concentration values were significantly shorter and lower, respectively, on the moderately resistant variety compared to the other varieties, thus indicating that the two control methods are compatible as part of an integrated pest management strategy. Thrips raised on the tolerant variety incurred an exceptionally low level of mortality when the inoculum was sprayed directly on the insects or when the insects were exposed tofungus-treated floral tissues. Observations on the effects of airborne volatiles and crude extracts of this variety revealed an inhibitory effect on fungal germination, colony forming units and growth. This suggests the existence of anti-fungal substances in the tolerant variety.
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    Storage and formulation of the entomopathogenicnematodes Heterorhabditis indica and H. bacteriophora (2000)
    Springer
    BioControl 45 (2000), S. 483-500 
    Details
    ISSN: 1573-8248
    Keywords: adjuvants ; attapulgite ; bentonite ; infectivity ; osmolarity ; pH ; survival ; temperature ; Heterorhabditis bacteriophora ; Heterorhabditis indica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Successful control of insect pests through theapplication of entomopathogenic nematode dauerjuveniles of H. bacteriophora and H.indica can only be achieved when the nematodematerial reaches the end user in good condition.Storage and formulation techniques must provideoptimum conditions to guarantee a maximum survival andinfectivity of the nematodes. Nematode survival wastested at temperatures ranging between 5–25 °C.A maximum survival of H. indica was achieved at15 °C and the highest mortality at 5 °C.H. bacteriophora survived best at 7.5 °Cand least at 25 °C. An increase of the saltconcentration had positive effects on dauer juvenilesurvival in aqueous suspensions. Low pH between 6 and4 reduced the bacterial growth and prolonged survivalof stored dauer juveniles. Of the organic acidsascorbic, benzoic, citric and sorbic acid, onlyascorbic acid had a positive effect on H. indicasurvival. Extracts of the dried spice plants cinnamon,cloves, rosemary and oregano were tested. Enhancementof H. indica survival was recorded for cinnamonand cloves. Survival and infectivity of nematodesstored in attapulgite and bentonite clays and spongewere recorded over several weeks at different storagetemperatures. Infectivity was not influenced by thedifferent formulation materials. When stored insponge at 25 °C nematodes survived less than 1week and the formulation in clay could only prolongthis period for another week. At 5 °C thesurvival of H. bacteriophora in sponge wassuperior to that in clay, whereas H. indicasurvived less well in sponge than in clay at15 °C. Storage in aerated water at 5 °Cfor H. bacteriophora and at 15 °C for H. indica resulted in the lowest mortality. Forstorage at controlled conditions (temperature, pH andosmolarity), aerated water is superior to all othermethods tested and the addition of preservatives willincrease survival.
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    URL: http://dx.doi.org/10.1023/A:1026528727365
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    Temperature Effects on Soil Mineralization of Polylactic Acid Plastic in Laboratory Respirometers (1999)
    Springer
    Journal of polymers and the environment 7 (1999), S. 101-108 
    Details
    ISSN: 1572-8900
    Keywords: Polylactic acid ; temperature ; respirometers ; soil degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A respirometric system was used to analyze the biodegradation of high molecular weight (120,000 to 200,000 g mol−1) polylactic acid (PLA) plastic films in soil under laboratory conditions. The respirometric system consisted of air-conditioning pretraps, a soil reactor, and a carbon dioxide (CO2) posttrap. A 200-g homogeneous soil mixture of all-purpose potting soil : manure soil : sand [1 : 1 : 1 (w/w)] and 1.5 g of PLA plastic films in 1 × 1-cm2 squares was added to each bottle. The respirometers were placed in a 28, 40, or 55°C water bath for 182 days. Treatments (three replicates) included native corn starch (positive control), polyethylene (Glad Cling Wrap; negative control), and three PLA films: Ca-I (Cargill Dow Polymers LLC, monolayer), GII (Cargill Dow Polymers LLC, Generation II), and Ch-I (Chronopol; monolayer). The degree of polymer mineralization was indicated by the cumulative CO2 liberated from each respirometer. The initial average mineralization rate and total percentage mineralized of the PLA plastic films at 28, 40, and 55°C was 24.3, 41.5, and 76.9 mg/day with a 27, 45, and 70% carbon loss, respectively. No decrease in soil pH was observed after 182 days of mineralization. Hence, increase in soil temperature drastically enhanced the biodegradation of PLA plastic films in soil under laboratory conditions (P 〈 0.0001).
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    URL: http://dx.doi.org/10.1023/A:1021812418325
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    Effects of Temperature and Relative Humidity on Polylactic Acid Plastic Degradation (1999)
    Springer
    Journal of polymers and the environment 7 (1999), S. 83-92 
    Details
    ISSN: 1572-8900
    Keywords: Polylactic acid ; temperature ; relative humidity ; degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Three high molecular weight (120,000 to 200,000 g mol−1) polylactic acid (PLA) plastic films from Chronopol (Ch-I) and Cargill Dow Polymers (GII and Ca-I) were analyzed for their degradation under various temperature and relative humidity (RH) conditions. Two sets of plastic films, each containing 11 samples, were randomly hung in a temperature/humidity-controlled chamber by means of plastic-coated paper clips. The tested conditions were 28, 40, and 55°C at 50 and 100% RH, respectively, and 55°C at 10% RH. The three tested PLA films started to lose their tensile properties when their weight-average molecular weight (M w) was in the range of 50,000 to 75,000 g mol−1. The average degradation rate of Ch-I, GII, and Ca-I was 28,931, 27,361, and 63,025 M w/week, respectively. Hence, GII had a faster degradation rate than Ch-I and Ca-I under all tested conditions. The degradation rate of PLA plastics was enhanced by the increase in temperature and relative humidity. This trend was observed in all three PLA plastics (Ca-I, GII, and Ch-I). Of the three tested films, Ch-I was the first to lose its mechanical properties, whereas Ca-I demonstrated the slowest loss, with mechanical properties under all tested conditions.
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    Oxidation of Styrene in a Silent Discharge Plasma (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 131-151 
    Details
    ISSN: 1572-8986
    Keywords: Styrene ; oxidation ; silent discharge ; plasma ; dielectric barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A silent discharge plasma reactor has been developed to study the oxidation of styrene vapor in argon/oxygen mixtures. A number of analytical techniques were employed to determine the destruction efficiency and to characterize the intermediate products. The destruction efficiency was measured as a function of initial styrene concentration, temperature, and energy density of the plasma. The formation of solid products was observed in most experiments. At low temperature (100°C), the solid deposit was polymeric in nature, while at high temperature (300°C) the solid appeared to be amorphous carbon. A combination of high temperature and high energy density resulted in high destruction efficiency and minimal production of solid films. The destruction efficiency vs. energy density is shown to be more complex than a simple model predicting exponential behavior. Several reasons for the discrepancy are suggested. The “e-folding” energy density for the destruction of styrene is compared to literature values for other organic compounds, measured using similar types of plasma reactors.
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    URL: http://dx.doi.org/10.1023/A:1021812201545
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    Oxidation of Dilute Benzene in an Alumina Hybrid Plasma Reactor at Atmospheric Pressure (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 383-394 
    Details
    ISSN: 1572-8986
    Keywords: Nonthermal plasma ; benzene ; Al2O3 ; BaTiO3 ; oxidation ; absorption ; atmospheric pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The combination of plasma discharge and adsorption was examined for oxidation of dilute benzene in air in a plasma reactor packed with a mixture of BaTiO 3 pellets and porous Al 2 O 3 pellets (i.e., an alumina hybrid reactor). The oxidative decomposition of benzene was enhanced by the benzene concentrating on the Al 2 O 3 pellets. Furthermore, there was a higher selectivity to CO 2 in the products from the hybrid than from a plasma reactor packed with BaTiO 3 pellets alone. The presence of the Al 2 O 3 pellets suppressed the formation of N 2 O.
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    URL: http://dx.doi.org/10.1023/A:1021820403362
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    Oxidation and Reduction Processes During NO x Removal with Corona-Induced Nonthermal Plasma (1999)
    Springer
    Plasma chemistry and plasma processing 19 (1999), S. 421-443 
    Details
    ISSN: 1572-8986
    Keywords: Streamer corona ; NO x removal ; nonthermal plasma ; oxidation ; reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this paper, the NO-to-NO 2 conversion in various gaseous mixtures is experimentally investigated. Streamer coronas are produced with a dc-superimposed high-frequency ac power supply (10–60 kHz). According to NO x removal experiments in N 2 +NO x and N 2 +O 2 +NO x gaseous mixtures, it is supposed that the reverse reaction NO 2 +O→NO+O 2 may not only limit NO 2 production in N 2 +NO x mixtures, but also increase the energy cost for NO removal. Oxygen could significantly suppress reduction reactions and enhance oxidation processes. The reduction reactions, such as N+NO→N 2 +O, induce negligible NO removal provided the O 2 concentration is larger than 3.6%. With adding H 2 O into the reactor, the produced NO 2 per unit removed NO can be significantly reduced due to NO 2 oxidation. NH 3 injection could also significantly decrease the produced NO 2 via NH and NH 2 - related reduction reactions. Almost 100% of NO 2 can be removed in gaseous mixtures of N 2 +O 2 +H 2 O+NO 2 with negligible NO production.
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    URL: http://dx.doi.org/10.1023/A:1021824504271
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    Universal Correlation of Nitrogen 1s and Oxygen 1s Photoelectron Binding Energies with Chemical Composition in Nitrogen-Containing Plasma Polymers (1999)
    Springer
    Plasmas and polymers 4 (1999), S. 283-307 
    Details
    ISSN: 1572-8978
    Keywords: Plasma polymers ; oxidation ; XPS ; photoelectron binding energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The incorporation of oxygen into nitrogen-containing plasma deposited polymers was studied by X-ray Photoelectron Spectroscopy (XPS). As the oxygen content of the plasma polymer increased, the binding energy of the N 1s photoelectrons increased. Conversely, the binding energy of the O 1s photoelectrons was inversely proportional to the nitrogen content of the plasma polymer. The data from a large number of samples all obeyed the same “universal” correlations of photoelectron binding energy versus chemical composition. The data were described by the same curve regardless of whether the oxygen was incorporated rapidly into the thin film during plasma deposition or whether the oxygen was added slowly during spontaneous oxidation of the film in air. This implies that the same thermodynamic principles of radical reactions governed the addition of oxygen to the plasma polymer. The shift in the O 1s and N 1s photoelectron binding energies as a function of chemical composition was used to monitor the proximity of nitrogen and oxygen. By contrasting the experimental data with a simple binomial model which described the random addition of oxygen to a lattice containing carbon and nitrogen, we were able to show that oxygen was preferentially added near nitrogen-containing groups in plasma polymers.
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    URL: http://dx.doi.org/10.1023/A:1021831527895
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    Algae of Lake Bai-Khol (Tuva, Russia) (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 171-176 
    Details
    ISSN: 1573-8590
    Keywords: algae ; Lake Bai-Khol ; salinity ; Uvs-Nuur Basin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The algal flora of Lake Bai-Khol, located in the endorheic Uvs-Nuur Basin, Russia, has been studied from collections made in August 1997. 79 taxa belonging to diatoms, blue-green and green algae were present.
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    URL: http://dx.doi.org/10.1023/A:1009019616569
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    A spatio-chemical survey of hydrogeothermal springs in Lake Elementaita, Kenya (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 127-138 
    Details
    ISSN: 1573-8590
    Keywords: Lake Elementaita ; Lake Nakuru ; origin ; salinity ; thermal springs ; water chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The hydrochemistry of three areas of geothermal activity in the Lake Elementaita basin were surveyed. The results indicated warm temperatures between 30--40°C, high alkalinity (1,200 mg CaCO3/l) and specific conductance (4,300--8,100 µS/cm). pH was above 9 with a high concentration of carbonates, chlorides and sulphates. Apart from playing a significant role in the lake chemistry, lacustrine springs provide a significant source of water supply, particularly during the dry season. However, there is a serious lack of scientific information on the hydrogeology and hydrochemistry of the thermal springs.
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    URL: http://dx.doi.org/10.1023/A:1009023717477
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    Comparisons between the reproductive biology of black breamAcanthopagrus butcheri (Teleostei: Sparidae) in four estuaries with widely differing characteristics (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 179-210 
    Details
    ISSN: 1573-8590
    Keywords: black bream ; estuaries ; fecundity ; fishery management ; length and age at maturity ; salinity ; spawning periods and locations ; water temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The reproductive biology ofAcanthopagrus butcheri has been studied in the permanently open Swan River and intermittently open Moore River estuaries on the lower west coast of Australia (31–32°S) and in the permanently open Nornalup Walpole and normally closed Wellstead estuaries on the southern coast of Western Australia (34–35°S). Trends exhibited by gonadosomatic indices, gonadal maturity stages and the sizes and developmental stages of the oocytes demonstrate thatA. butcheri typically spawns in spring and early summer. However, spawning occurred in salinities ranging from as low as 3.5–8 gL−1 in the Moore River Estuary to as high as 41–45 g L−1 in the Wellstead Estuary. Furthermore, water temperatures during spawning were greater in the two northern estuaries (19.7–28.5°C) than in the two southern and cooler estuaries (17.5–23.4°C). Histological studies strongly indicate thatA. butcheri spawn more than once in a breeding season and demonstrate that the development of its oocytes exhibits group synchronysensu de Vlaming (1983). The ages and total lengths at which, on average, female and maleA. butcheri both first attain maturity in the Swan River Estuary were ca 2 years and ca 215 mm. However, the age at which individual fish in that system reach maturity was influenced by body size. This suggests that the attainment of first maturity at an older age but smaller length in the Moore River and Nornalup Walpole estuaries than is the case in the Swan River Estuary is a consequence of the slower growth rates ofA. butcheri in those estuaries. The combination of the young age (ca 2 years) but small length (ca 145 mm) at which maturity is first attained in the Wellstead Estuary could have resulted from selection pressures brought about by high mortality rates and/or heavy fishing pressure in this estuary. The mean fecundity ofA. butcheri, based on the combined number of yolk vesicle and yolk granule oocytes found in ovaries just prior to the onset of spawning, was 1580×103. The significance of the sizes at first maturity, minimum legal length for capture, mesh selectivity data and closure of certain regions of estuaries to fishing for the management of the recreational and commercial fishery forA. butcheri is discussed.
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    Salinity of surface waters in the Aral Sea region (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 293-306 
    Details
    ISSN: 1573-8590
    Keywords: Aral Sea ; salinity ; salinization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract An overview of recent changes insalinity in the surface waters of the Aral sea basinis given. Total dissolved salts (salinity) in mostwaters are higher than admissible values fordrinking water, and ionic composition has changed withtime. Salinity of the `Big Sea' of the Aral was 48g L−1 in 1998, but has decreased to below 21g L−1 in the `Small Sea' due to the building ofa new dam between the two parts of the Aral Sea.
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    Effects of Temperature on Growth and Efficiency of Yolk Utilisation in Eggs and Pre-feeding Larval Stages of Atlantic Salmon (1999)
    Springer
    Aquaculture international 7 (1999), S. 81-87 
    Details
    ISSN: 1573-143X
    Keywords: alevin ; Atlantic salmon (Salmo salar) ; development ; egg ; temperature ; thermal tolerance ; yolk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three embryonic stages of Atlantic salmon (Salmo salar L.) were subjected to eight constant incubation temperatures (4, 7, 10, 12, 14, 16, 19 and 22 °C) exceeding the range usually experienced in natural conditions. A change in thermal tolerance during the embryonic and larval development was registered: pre-hatching stages showed an upper thermal limit at about 16 °C, while hatched larvae survived until 22 °C. Temperature significantly affects developmental rate, resulting in a faster development and, consequently, lower yolk weight percentage at higher temperatures. We found positive relationships between incubation temperature and body size (length and weight) in the less developed stages, in which some yolk remained, but size decreased at increasing temperatures when yolk was completely exhausted.
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    Growth and Chemical Composition of Spirulina Maxima and Spirulina Platensis Biomass at Different Temperatures (1999)
    Springer
    Aquaculture international 7 (1999), S. 261-275 
    Details
    ISSN: 1573-143X
    Keywords: cyanobacteria ; microalgae ; Spirulina ; Spirulina composition ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of temperature on growth and biomass composition of two species of Spirulina, S. maxima and S. platensis used for food was studied. A 4L fermenter with temperature and agitation control was used to cultivate both species. Under continuous light, maximum cell production of 2.4 g l−1 was verified for both cultures studied at temperatures above 25 °C: S. maxima (30 °C and 35 °C) and S. platensis (25 °C and 30 °C). An accentuated lag phase was observed for all cultures at lower temperatures (15–20 °C), and a maximum biomass production of 1.5 g l−1 was achieved. It was also observed that an increase of temperature caused a marked decrease in protein content, while carbohydrate synthesis was stimulated. The concentration of γ-linolenic acid varied from 11–16% for S. maxima and from 12–14% for S. platensis, at the optimum growth temperatures. Greater culture volumes were also studied in order to compare the performance of glass and plastic containers. At optimum growth temperature, S. maxima produced the same cell growth and similar final biomass composition.
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    A spatio-chemical survey of hydrogeothermal springs in Lake Elementaita, Kenya (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 127-138 
    Details
    ISSN: 1573-8590
    Keywords: Lake Elementaita ; Lake Nakuru ; origin ; salinity ; thermal springs ; water chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The hydrochemistry of three areas of geothermal activity in the Lake Elementaita basin were surveyed. The results indicated warm temperatures between 30–40°C, high alkalinity (1,200 mg CaCO3/l) and specific conductance (4,300–8,100 μS/cm). pH was above 9 with a high concentration of carbonates, chlorides and sulphates. Apart from playing a significant role in the lake chemistry, lacustrine springs provide a significant source of water supply, particularly during the dry season. However, there is a serious lack of scientific information on the hydrogeology and hydrochemistry of the thermal springs.
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    URL: http://dx.doi.org/10.1007/BF02442126
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    Hydrological exchange and subsurface water chemistry in streams varying in salinity in south-western Australia (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 361-382 
    Details
    ISSN: 1573-8590
    Keywords: Aral Sea ; salinity ; salinization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Many streams in Western Australia are naturally saline. In others, especiallyin the south-western corner, land-clearance and other human activities inthe catchment have accelerated rates of salinisation of surface andgroundwater. Trends in surface water salinity are well-documented but theextent of penetration of saline stream water into the sediments has beenlittle studied. As many of these streams have porous sandy beds and theirflows may derive from groundwater, hydrologic exchange patterns betweensurface water and subsurface hyporheic water were hypothesised togovern the water chemistry of such rivers. We predicted high rates ofhydraulic conductivity, leading to a close relationship between surface andsubsurface (to a depth of 50 cm) salinity, and to a lesser extent, pH anddissolved oxygen. Where surface and hyporheic water differed in salinity,other chemical differences were hypothesised to be similarly marked,perhaps resulting from disjunct shallow subsurface aquifers. Triplicatewells were sampled from upwelling and downwelling zones of thirteenstreams ranging in salinity from ca. 0.2 to 18 g L−1. Despite theseemingly-porous sandy beds at many sites, subsurface water chemistryonly 20–40 cm below the bed sometimes differed markedly from surfacewater. For example, hyporheic water was only one-fifth the salinity ofsurface water at some saline sites (e.g., the Tone River) or 20 per cent moresaline in streams with fresh surface water (e.g., the Weld River). At somesites of intermediate salinity (e.g., the Warren River), subsurface water wasup to three times fresher than surface or downwelling water. Percentagesaturation of dissolved oxygen in the hyporheic water was consistently low(〈 40%) whereas pH was more acidic than surface water, presumably dueto microbial activity. Vertical hydraulic conductivity may be limited bylayers of fine sediments and clays, implying that the meso-scale (1–100 cm)hydrological dynamics within the hyporheic zones of these rivers are morecomplex than their sandy beds would indicate. Assumptions of ecosystemdynamics in saline streams must be tempered by an understanding ofhyporheic salinities as subsurface fresher water may support microbial andfaunal assemblages excluded from the surface benthos by high salinity. Insaline streams, as in fresh ones, the hyporheic zone is an importantcomponent of the stream ecosystem and equally prone to disruption byhuman activities.
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    The salinity of hypersaline brines: Concepts and misconceptions (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 55-70 
    Details
    ISSN: 1573-8590
    Keywords: Dead Sea ; equation of state ; pycnometry ; salinity ; saturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Some widespread misconceptions about salinity are pointed out, explained and commented on. Definitions, units, and methods of salinity determination recommended for brines of moderate salinities may become unsuitable for highly saline brines. Various salinity units are examined and commented on, and density at a precisely monitored temperature is chosen as the preferable “substitute parameter” for salinity determination of hypersaline brines. It is shown that ambient air density during pycnometric measurements must be known as accurately as required of the brine's density, and that its value must be added to the direct pycnometric measurement. Variations of atmospheric pressure at the time of pycnometry must be taken into account if greater than 15 mB. For a salinity accuracy of ±0.02 per mille, as required for some physical and chemical studies, the temperature of the sample during salinity measurement must be monitored with an accuracy of at least 0.04°C. A definite curve in the ρ-S plane, corresponding to the conversion of salinity to density at a fixed temperature, andvice-versa, does not exist if the brine is saturated in one of its salts. Non-linearity in the equation of state is shown to affect the surface level drop due to evaporation; the effect is negligible at low salinities, but a 10 per cent correction is already required at the salinity found in the northern Red Sea (41 per mille). Reliable reference points for the conversion of absolute salinity to density of highly saline brines are not known, at present, as accurately as desirable; pending the accurate determination of such reference points, a substantial dilution of hypersaline brines (for the purpose of adapting them to conductivity measurements) would multiply the error range by more than a hundred fold. On the other hand, a minute dilution of hypersaline brine samples to prevent salt crystal formation is possible and would not bring about any major increase of the error range in their density (salinity) determination.
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    Algae of Lake Bai-Khol (Tuva, Russia) (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 171-176 
    Details
    ISSN: 1573-8590
    Keywords: algae ; Lake Bai-Khol ; salinity ; Uvs-Nuur Basin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The algal flora of Lake Bai-Khol, located in the endorheic Uvs-Nuur Basin, Russia, has been studied from collections made in August 1997. 79 taxa belonging to diatoms, blue-green and green algae were present.
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    URL: http://dx.doi.org/10.1007/BF02442129
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    The salinity of hypersaline brines: Concepts and misconceptions (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 55-70 
    Details
    ISSN: 1573-8590
    Keywords: Dead Sea ; equation of state ; pycnometry ; salinity ; saturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Some widespread misconceptions about salinity are pointed out, explained and commented on. Definitions, units, and methods of salinity determination recommended for brines of moderate salinities may become unsuitable for highly saline brines. Various salinity units are examined and commented on, and density at a precisely monitored temperature is chosen as the preferable “substitute parameter” for salinity determination of hypersaline brines. It is shown that ambient air density during pycnometric measurements must be known as accurately as required of the brine's density, and that its value must be added to the direct pycnometric measurement. Variations of atmospheric pressure at the time of pycnometry must be taken into account if greater than 15 mB. For a salinity accuracy of ±0.02 per mille, as required for some physical and chemical studies, the temperature of the sample during salinity measurement must be monitored with an accuracy of at least 0.04°C. A definite curve in the ρ-S plane, corresponding to the conversion of salinity to density at a fixed temperature, and vice-versa, does not exist if the brine is saturated in one of its salts. Non-linearity in the equation of state is shown to affect the surface level drop due to evaporation; the effect is negligible at low salinities, but a 10 per cent correction is already required at the salinity found in the northern Red Sea (41 per mille). Reliable reference points for the conversion of absolute salinity to density of highly saline brines are not known, at present, as accurately as desirable; pending the accurate determination of such reference points, a substantial dilution of hypersaline brines (for the purpose of adapting them to conductivity measurements) would multiply the error range by more than a hundred fold. On the other hand, a minute dilution of hypersaline brine samples to prevent salt crystal formation is possible and would not bring about any major increase of the error range in their density (salinity) determination.
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    Comparisons between the reproductive biology of black bream Acanthopagrus butcheri (Teleostei: Sparidae) in four estuaries with widely differing characteristics (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 179-210 
    Details
    ISSN: 1573-8590
    Keywords: black bream ; estuaries ; fecundity ; fishery management ; length and age at maturity ; salinity ; spawning periods and locations ; water temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The reproductive biology of Acanthopagrus butcheri has been studied in the permanently open Swan River and intermittently open Moore River estuaries on the lower west coast of Australia (31--32 °S) and in the permanently open Nornalup Walpole and normally closed Wellstead estuaries on the southern coast of Western Australia (34--35 °S). Trends exhibited by gonadosomatic indices, gonadal maturity stages and the sizes and developmental stages of the oocytes demonstrate that A. butcher typically spawns in spring and early summer. However, spawning occurred in salinities ranging from as low as 3.5-8 g L−1 in the Moore River Estuary to as high as 41-45 g L−1 in the Wellstead Estuary. Furthermore, water temperatures during spawning were greater in the two northern estuaries (19.7--28.5 °C) than in the two southern and cooler estuaries (17.5--23.4 °C). Histological studies strongly indicate that A. butcheri spawn more than once in a breeding season and demonstrate that the development of its oocytes exhibits group synchrony sensu de Vlaming (1983). The ages and total lengths at which, on average, female and male A. butcheri both first attain maturity in the Swan River Estuary were ca 2 years and ca 215 mm. However, the age at which individual fish in that system reach maturity was influenced by body size. This suggests that the attainment of first maturity at an older age but smaller length in the Moore River and Nornalup Walpole estuaries than is the case in the Swan River Estuary is a consequence of the slower growth rates of A. butcheri in those estuaries. The combination of the young age (ca 2 years) but small length (ca 145 mm) at which maturity is first attained in the Wellstead Estuary could have resulted from selection pressures brought about by high mortality rates and/or heavy fishing pressure in this estuary. The mean fecundity of A. butcheri, based on the combined number of yolk vesicle and yolk granule oocytes found in ovaries just prior to the onset of spawning, was 1580 × 103. The significance of the sizes at first maturity, minimum legal length for capture, mesh selectivity data and closure of certain regions of estuaries to fishing for the management of the recreational and commercial fishery for A. butcheri is discussed.
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    Salinity of surface waters in the Aral sea region (1999)
    Springer
    International journal of salt lake research 8 (1999), S. 293-306 
    Details
    ISSN: 1573-8590
    Keywords: Aral Sea ; salinity ; salinization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract An overview of recent changes in salinity in the surface waters of the Aral sea basin is given. Total dissolved salts (salinity) in most waters are higher than admissible values for drinking water, and ionic composition has changed with time. Salinity of the ‘Big Sea’ of the Aral was 48 g L−1 in 1998, but has decreased to below 21 g L−1 in the ‘Small Sea’ due to the building of a new dam between the two parts of the Aral Sea.
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    URL: http://dx.doi.org/10.1007/BF02442116
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    Effects of Temperature on Infection in Capsicum sp. and Nicotiana benthamiana by Impatiens Necrotic Spot Tospovirus (1999)
    Springer
    European journal of plant pathology 105 (1999), S. 509-512 
    Details
    ISSN: 1573-8469
    Keywords: tospovirus ; resistance ; Capsicum sp. ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Infection by two isolates of impatiens necrotic spot tospovirus (INSV) under temperature regimes of 25/18°C (day/night) or 33°C (continuous) was studied in Capsicum annuum (systemically susceptible to tomato spotted wilt tospovirus, TSWV), C. chinense PI 152225 and PI 159236 (reacting hypersensitively to TSWV) and Nicotiana benthamiana (systemically susceptible to both tospoviruses). At 25/18°C infection was systemic in all hosts tested. At 33°C infection in N. benthamiana was systemic whereas in C. annuum and C. chinense it was restricted to the inoculated leaves. The result differed from that reported for TSWV, where high temperature made plants more susceptible, or caused no difference. Exchanging temperature regimes 6 h to 4 days after inoculation did not affect the final results one month later, with plants being only locally infected at 33°C continuous regime, or systemically infected at 25/18°C alternate regime. The two INSV isolates were biologically and serologically stable for 5 passages in N. benthamiana held continuously at 33°C.
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    Floral initiation in field-grown forage peas is delayed to a greater extent by short photoperiods, than in other types of European varieties (1999)
    Springer
    Euphytica 109 (1999), S. 201-211 
    Details
    ISSN: 1573-5060
    Keywords: Pisum sativum L. ; frost resistance ; floral initiation ; photoperiod ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Frost is one of the main climatic stresses which has to be overcome by a winter pea crop. Some forage lines show a delayed floral initiation, which helps them to escape the main winter freezing periods, as a higher susceptibility to frost is observed after floral initiation commences. Frost tolerant forage peas have been used in all winter pea breeding programs in France and our main purpose was to evaluate to what extent those lines and the current winter varieties are variable for the date of floral initiation in field conditions. A field experiment was carried out during two years at the INRA experimental station of Mons (northern France). Different genotypes (9 in 1995–1996 and 12 in 1996–1997) were sown at approximately monthly intervals between September and June to provide a range of photothermal conditions. The date of floral initiation was determined by destructive sampling. We observed variability for the date of floral initiation among the different genotypes and sowing dates. Our data particularly highlighted the different reactions to photoperiod. Three varieties had no detectable reaction. Six varieties exhibited a quantitative response, with varied intensities. Lastly, the three forage varieties showed a qualitative, high response to photoperiod, which indicated the presence of the Hr allele, already described in Pisum.
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    Effect of salinity on the association between root symbionts and Acacia cyanophylla Lind.: growth and nutrition (1999)
    Springer
    Plant and soil 216 (1999), S. 93-101 
    Details
    ISSN: 1573-5036
    Keywords: Acacia cyanophylla ; endomycorrhizae ; growth ; nutrition ; Rhizobia ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The behaviour of Acacia cyanophylla Lind. plants submitted to salinity stress was followed in the greenhouse. The plants were associated with indigenous symbiotic microorganisms isolated from the coastal dunes of the Souss-Massa region. A two months period of salinity had a large negative impact on plant growth and acquisition of macro nutrients. However, the study underlined the role of the microbial inoculum for the plant in the achievement of salt tolerance. An isolate of Bradyrhizobium sp., RCM6 (R1), originating from the Massa dunes, was highly efficient in improving growth and nutrition of the A. cyanophylla. Double inoculation with the rhizobia and an endomycorrhizal complex, isolated from the Lamzar dunes had a clear additional positive effect, i.e. the fungi further increased the tolerance of the A. cyanophylla plants to salinity.
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    URL: http://dx.doi.org/10.1023/A:1004745707277
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    Ammonium and nitrate uptake by Eucalyptus nitens: effects of pH and temperature (1999)
    Springer
    Plant and soil 214 (1999), S. 133-140 
    Details
    ISSN: 1573-5036
    Keywords: ammonium ; eucalyptus ; nitrate ; pH ; root uptake ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ammonium and nitrate uptake by roots of Eucalyptus nitens was characterised with respect to pH and temperature. Uptake of ammonium and nitrate was measured as depletion from solutions by roots of intact 11 week old solution-cultured seedlings. Uptake rates of ammonium were consistently higher than those of nitrate in all experiments. Uptake rates for ammonium were 200% higher at pH 4 than at pH 6, but for nitrate were unchanged. Uptake rates of ammonium and nitrate were both reduced to a similar extent (70%) with a decrease in temperature from 20 °C to 10 °C. For ammonium uptake, there was rapid (〈24 hr) adaptation to a reduction in root temperature. The apparent preference shown here for ammonium over nitrate could be indicative of E. nitens growing in cold, acidic forest soils where ammonium is commonly more available than nitrate. These results suggest that N uptake rates of E. nitens may be maximised under a wide variety of conditions if N is supplied predominantly in the ammonium form.
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    Feed Intake and Growth of Juvenile Silver Trevally at the Southern Limit of Their Distribution (1999)
    Springer
    Aquaculture international 7 (1999), S. 357-360 
    Details
    ISSN: 1573-143X
    Keywords: feed intake ; growth ; silver trevally (Pseudocaranx dentex) ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009296531292
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    Temperature effects on soil organic sulphur mineralization and elemental sulphur oxidation in subtropical soils of varying pH (1999)
    Springer
    Nutrient cycling in agroecosystems 54 (1999), S. 175-182 
    Details
    ISSN: 1573-0867
    Keywords: elemental sulphur ; oxidation ; organic S ; mineralization ; immobilization ; S fertilizers ; semiarid soils ; subtropical region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The increasing sulphur (S) deficiency in soils of several parts of world has led to the use of fertilizer S, an important factor in enhancing the production and quality of crops. Very limited information is available on the use of elemental sulphur (S0) as a fertilizer, its oxidation into SO42- and transformation into organic S in semiarid subtropical soils. We studied the impact of three temperature regimes on the mineralization of soil organic S, and the oxidation and immobilization of S0 in acidic (pH 4.9), neutral (pH 7.1) and alkaline (pH 10.2) subtropical soils of north-western India. Repacked soil cores were incubated under aerobic conditions (60% water-filled pore space) for 0, 14, 28 and 42 d with and without incorporated S0 (500 μg g-1 soil). Temperature had profound effects on all three soils processes, the rates of mineralization of native soil organic S, oxidation of applied S0 and transformation of S0 into soil organic S being greatest at 36 °C, irrespective of soil pH. Mineralization of native soil organic S (without added S0) resulted in the accumulation of 39, 66 and 47 μg SO42-–S g-1 soil in acidic, neutral and alkaline soil in 42 d period at 36 °C. Of the total mineralization, the majority (62 – 74%) occurred during the first 14 d period. Oxidation rate of added S0 during initial 14 d period at 36 °C was highest in alkaline soil (292 μg S cm-2 d-1), followed by neutral soil ((180 μg S cm-2 d-1) and lowest in acidic soil (125 μg S cm-2 d-1). Of the applied 500 μg S0 g-1 soil, 3.2 – 10.0%, 6.8 – 15.4% and 10.0 – 23.0% oxidized to SO42-, and 13.4 – 28.6%, 16.0 – 29.0% and 14.6 – 29.0% were transformed into organic S in 42 d period in acidic, neutral and alkaline soil, respectively. The results of our study suggest that in order to synchronize the availability of S with plant need, elemental S may be applied well before the seeding of crops, especially in acidic soil and in regions where temperature remains low. Substantial mineralization of native soil organic S in the absence of applied S0 and immobilization of applied S0 into organic S suggest that the role of soil biomass as source and sink could be exploited in long term S management.
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    URL: http://dx.doi.org/10.1023/A:1009770919296
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    Effect of source and nest size of N fertilizers and temperature on nitrification in a coarse textured, alkaline soil (1999)
    Springer
    Nutrient cycling in agroecosystems 54 (1999), S. 199-207 
    Details
    ISSN: 1573-0867
    Keywords: ammonium chloride ; ammonium sulphate ; nest placement ; nitrification ; temperature ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrification occurring in an alkaline sandy loam soil fertilized with urea, ammonium sulphate (AS) and ammonium chloride (AC) was studied in the laboratory at 20°C and 40°C for 30 days. Nitrogen fertilizers were applied as nest of sizes 0.2, 0.5, 1.0 and 2.0 g. Unfertilized control and soil mixed with 50 mg N kg-1 were also included as treatments. Nitrification in all the fertilizer treatments decreased markedly with increasing nest size. At 20°C, differences among the three N sources were not significant at 5 days after incubation but marked differences appeared thereafter. All the N was nitrified by 30 days in case of fertilizers mixed into the soil. In nest placement, nitrification ranged from 30.1 to 75.5%, 28.3 to 74.6% and 35.3 to 88.7% for urea, AC and AS, respectively. When equal amounts of fertilizers were placed in a nest, nitrification occurred at a slower rate with urea than with AC and AS. Rates of nitrification were significantly higher at 40°C than at 20°C. At 20 days, nitrification from different nest sizes ranged from 8.4 to 64.9% and from 24.9 to 87.0% at 20°C and 40°C, respectively. The difference in nitrification at two temperatures were more pronounced at higher nest sizes than at smaller nest sizes. While nitrification with the three N sources decreased linearly with increase in N concentration (nest size) in soil at 40°C, it showed a quadratic relationship at 20°C. At equal N concentration, the highest rate of nitrification occurred with urea and the lowest with AC. At the same rate of applied N (50–2000 mg kg-1), AC and AS increased electrical conductivity of soil by 1.3–9 times that of urea. Apparent mineral N recovery of applied N decreased with the increase in nest size.
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    Realizing the Potential of Integrated Irrigation and Drainage Water Management for Meeting Crop Water Requirements in Semi-Arid and Arid Areas (1999)
    Springer
    Irrigation and drainage systems 13 (1999), S. 321-347 
    Details
    ISSN: 1573-0654
    Keywords: cotton ; drainage ; irrigation ; salinity ; shallow groundwater ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In situ use of ground water by plants is one optionbeing considered to reduce discharge of subsurfacedrainage water from irrigated agriculture. Laboratory, lysimeter, and field studies havedemonstrated that crops can use significant quantitiesof water from shallow ground water. However, moststudies lack the data needed to include the crop wateruse into an integrated irrigation and drainage watermanagement system. This paper describes previousstudies which demonstrated the potential use of groundwater to support plant growth and the associatedlimitations. Included are results from three fieldstudies which demonstrated some of the managementtechniques needed to develop an integrated system. The field studies demonstrated that approximately 40to 45% of the water requirement for cotton can bederived from shallow saline ground water. Thatregulation of the outflow will result in increasinguse. Implementation of integrated management ofirrigation and subsurface drainage systems is a viableand sustainable alternative in the management ofsubsurface drainage water from arid and semi-aridareas only if soil salinity can be managed and if thesystem is profitable.
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    URL: http://dx.doi.org/10.1023/A:1006390421589
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    Transformation of diphenyl ethers by Trametes versicolor and characterization of ring cleavage products (1999)
    Springer
    Biodegradation 10 (1999), S. 279-286 
    Details
    ISSN: 1572-9729
    Keywords: Diphenyl ether ; ligninolytic enzymes ; metabolites ; oxidation ; Trametes versicolor ; white-rot fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The white-rot fungi Trametes versicolor SBUG 1050, DSM 11269 and DSM 11309 are able to oxidize diphenyl ether and its halogenated derivatives 4-bromo- and 4-chlorodiphenyl ether. The products formed from diphenyl ether were 2- and 4-hydroxydiphenyl ether. Both 4-bromo- and 4-chlorodiphenyl ether were transformed to the corresponding products hydroxylated at the non-halogenated ring. Additionally, ring-cleavage products were detected by high perfomance liquid chromatography and characterized by gas chromatography/mass spectrometry and proton nuclear magnetic resonance spectroscopy. Unhalogenated diphenyl ether was degraded to 2-hydroxy-4-phenoxymuconic acid and 6-carboxy-4-phenoxy-2-pyrone. Brominated derivatives of both these compounds were formed from 4-bromodiphenyl ether, and 4-chlorodiphenyl ether was transformed in the same way to the analogous chlorinated ring cleavage products. Additionally, 4-bromo- and 4-chlorophenol were detected as intermediates from 4-bromo- and 4-chlorodiphenyl ether, respectively. In the presence of the cytochrome-P450 inhibitor 1-aminobenzotriazole, no metabolites were formed by cells of Trametes versicolor from the diphenyl ethers investigated. Cell-free supernatants of whole cultures with high laccase and manganese peroxidase activities were not able to transform the unhydroxylated diphenyl ethers used.
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    Agroforestry for water management in the cropping zone of southern Australia (1999)
    Springer
    Agroforestry systems 45 (1999), S. 277-302 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; deep drainage ; revegetation ; salinity ; tree crop interactions ; tree water use
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agroforestry has been advocated as a means of managing excess water that has accumulated in the agricultural landscape of southern Australia since clearing of native vegetation. This article examines the feasibility and profitability of agroforestry systems designed to manage rising, saline watertables. A framework for Australian conditions is described that considers the interactions between trees, crops and their below ground environment and how they influence water use, crop yield and profitability. Data is presented from a study of a commercial scale agroforestry system under ideal conditions where trees have access to a shallow fresh water table. The discussion is then broadened to encompass soil, relief and ground water conditions more typical of the southern Australian cropping zone. The relative merits of segregating, integrating and rotating trees with crops are then examined. It is concluded that, in most cases, trees would need to be widely dispersed over a significant proportion of the landscape to manage deep drainage and salinity. Agroforestry is therefore only likely to be an effective solution to water management where trees can compete directly on commercial terms with conventional agriculture. Given the generally low rates of biomass accumulation in semi-arid woody species, this presents a significant challenge for agroforestry in the cropping zone of southern Australia.
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    Applicability of Fatigue Life Prediction Method to Polymer Composites (1999)
    Springer
    Mechanics of time-dependent materials 3 (1999), S. 141-157 
    Details
    ISSN: 1573-2738
    Keywords: CFRP ; fatigue ; frequency ; stress ratio ; temperature ; viscoelasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A prediction method of fatigue strength under an arbitraryfrequency, temperature, and stress ratio is proposed for polymercomposites and its validity is confirmed for the flexural fatiguestrength of satin-woven CFRP laminates. This method is based upon fourhypotheses: (a) same failure process under constant strain-rate (CSR),creep, and fatigue loadings, (b) same time-temperature superpositionprinciple for all failure strengths, (c) linear cumulative damage lawfor nondecreasing stress process, and (d) linear dependence of fatiguestrength upon stress ratio. This method was applied to the flexuralfatigue strength of various unidirectional CFRPs, and the verificationand limitations of this method were discussed.
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    The influence of temperature, photoperiod and plant type on the predation rate of Macrolophus pygmaeus on Myzus persicae (1999)
    Springer
    BioControl 44 (1999), S. 281-289 
    Details
    ISSN: 1573-8248
    Keywords: Macrolophus pygmaeus ; photoperiod ; predation rate ; temperature ; predator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of temperature and photoperiod on the rate of predation of nymphs and adults of the predator Macrolophus pygmaeus was studied using Myzus persicae prey feeding on egg-plant and pepper plants. The experiments were conducted at three photoperiods (16L:8D, 12L:12D and 8L:16D), three temperatures (20, 25 and 30 °C), and at 65% r.h. The rate of predation increased with temperature. Predation rate was affected by photoperiod on pepper but not on egg-plant. Females and fifth instar nymphs were the most voracious stages followed by third and fourth instar nymphs and males. First and second instar nymphs consumed far fewer aphids. Predation rate was higher on leaves of pepper than egg-plant, especially at 30 °C. Variation in the efficacy of this predator is discussed.
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    Competitive ability of the antagonists Ulocladium atrum and Gliocladium roseum at temperatures favourable for Botrytis spp. development (1999)
    Springer
    BioControl 44 (1999), S. 329-346 
    Details
    ISSN: 1573-8248
    Keywords: biological control ; Botrytis aclada ; Botrytis cinerea ; cyclamen ; ecological adaptation ; hydrangea ; lily ; onion ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ulocladium atrum and Gliocladium roseum are fungal antagonists capable of suppressing sporulation of Botrytis spp. on dead plant parts. The effect of temperature (3 to 36 °C) on antagonist conidial germination and mycelial growth was assessed on agar. In addition conidial germination of U. atrum was measured on dead lily leaves. The optimum temperature of both antagonists for both conidial germination and mycelial growth was between 27 and 30 °C. U. atrum was less affected by lower temperatures than G. roseum. At optimum temperature, 50% of conidia of U. atrum and G. roseum germinated within 2.6 and 10.0 hrs, respectively. At low sub-optimal temperatures (6 °C), 50% of conidia germinated within 18 and 96 hours, respectively. In bioassays on dead onion leaves, U. atrum suppressed sporulation of B. cinerea and B. aclada at all temperatures tested (6 to 24 °C) by more than 85%. On dead cyclamen leaves, G. roseum was more efficient than U. atrum at 21 and 24 °C but, in contrast to U. atrum, showed no antagonistic activity at temperatures below 21 °C. On dead hydrangea leaves, U. atrum significantly reduced sporulation of B. cinerea at temperatures as low as 3 and 1 °C. Under Dutch growing conditions, the mean air temperature during leaf wetness periods in onion and lily fields was 15 °C with temperatures only occasionally above 20 °C. In greenhouse crops of cyclamen, the mean temperature during high humidity periods was 17 °C. It is therefore concluded that U. atrum is better adapted than G. roseum to temperatures which occur in the field, in greenhouse crops such as cyclamen, or during cold storage of plant stocks.
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    Methodology for minimizing effects of temperature in monitoring with the acousto-ultrasonic technique (1999)
    Springer
    Experimental mechanics 39 (1999), S. 86-91 
    Details
    ISSN: 1741-2765
    Keywords: Acousto-ultrasonic ; damage monitoring ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The acousto-ultrasonic (AU) technique can be a useful methodology for monitoring structures or mechanical components during endurance tests, fatigue tests or, in general, during the life of the components. To obtain reliable information about the failure and fatigue cracks at their earliest initiation stages and to follow their evolution regardless of any disturbance effects, refined experimental procedures and signal processing are needed. In particular, the effects of temperature variation cannot be entirely suppressed and are difficult to evaluate. This means that the results of the AU technique are not immediately interpretable and usable for monitoring structures. This paper describes some procedures aimed at minimizing the effects of disturbance on AU signals caused by temperature variation, allowing use of AU for monitoring over extensive periods of time or when the component is subjected to heating.
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    URL: http://dx.doi.org/10.1007/BF02331110
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    Preparation of Polyuronic Acid from Cellulose by TEMPO-mediated Oxidation (1998)
    Springer
    Cellulose 5 (1998), S. 153-164 
    Details
    ISSN: 1572-882X
    Keywords: cellulose ; TEMPO ; polyglucuronic acid ; degree of polymerization ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Various cellulose samples were oxidized by 2,2,6,6,-tetramethylpipelidine-1-oxyl radical (TEMPO)-NaBr-NaClO systems, and the effects of oxidation conditions on chemical structures and degrees of polymerization of the products obtained were studied. In the case of regenerated and mercerized celluloses, almost all C6 primary alcohol groups were selectively oxidized to carboxyl groups, and water-soluble polyglucuronic acid (cellouronic acid) sodium salts were obtained almost quantitatively; the degrees of polymerization were influenced greatly by the amount of TEMPO added, and the oxidation time and temperatures. Cellouronic acids prepared from mercerized linter and kraft pulps had size exclusion chromatograms with two separate peaks due to higher and lower molecular weight fractions. On the other hand, only small amounts of carboxyl groups were introduced into native cellulose samples. Since polyglucuronic acids prepared from cellulose by the TEMPO–NaBr– NaClO systems regularly consist of the glucuronic acid repeating unit, differing from the conventional water-soluble cellulose derivatives, they may open new fields of cellulose utilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009208603673
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  • 86
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    Thermoelastic contact problem of two rotating bodies with frictional heat generation in annular region (1998)
    Springer
    Archive of applied mechanics 68 (1998), S. 128-136 
    Details
    ISSN: 1432-0681
    Keywords: Key words frictional heating ; temperature ; contact pressure ; punch indentation ; thermoelasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary An axisymmetric contact problem with frictional heating is considered in which a parabolic annular punch is pressed into a plane surface and rotates about its axis of symmetry at constant speed. The problem is formulated in terms of one governing equation with unknown pressure. This equation is solved numerically. The change of the geometry of the contact region and pressure has been investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004190050150
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  • 87
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    Tetrachlorosilane Consumption in Radio Frequency Glow Discharge (1998)
    Springer
    Plasma chemistry and plasma processing 18 (1998), S. 509-533 
    Details
    ISSN: 1572-8986
    Keywords: RF SiCl4 discharge ; mass spectrometry ; kinetics ; decomposition ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Time-resolved mass spectrometry was used for analysis of the plasma reactions in radio frequency (RF) SiCl 4 and SiCl 4 −O 2 discharges as functions of starting partial pressure and electrical power. Molecular concentrations of the reactants and products from SiCl 4 alone and with O 2 were obtained from the mass spectra and used for plotting the kinetic curves. The SiCl 4 and O 2 consumption rates were calculated from the kinetic curves and compared with results of theoretical simulation of the reaction. Direct electron impact decomposition was found to be the main pathway for pure SiCl 4 conversion. On the contrary, the consumption of SiCl 4 in the SiCl 4 +O 2 mixtures was largely chemical. The experimental macrokinetics are in agreement with a model in which oxidation is caused by the atomic oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021811316740
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  • 88
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    Towards a Predictive Design Methodology Based on the Physical Modelling of the Fracture of Fiber Composites (1998)
    Springer
    Applied composite materials 5 (1998), S. 69-94 
    Details
    ISSN: 1573-4897
    Keywords: modelling ; notch strength ; damage ; fatigue ; environment ; temperature ; prediction ; design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A predictive design methodology based on modelling the fracture stress (notched tensile strength) and post-fatigue residual strength of laminated fiber composites is presented. The approach is based explicitly on the development of models of the physical processes by which damage accumulates at a notch-tip and the application of these models to cross-ply laminates for a variety of material systems, including thermosetting and thermoplastic matrices containing carbon, glass and Kevlar fiber reinforcements. The effects of temperature and humidity on composite fracture can also be examined in the context of this modelling strategy. A pre-requisite of the model is that it has to be calibrated for each material system by performing tensile tests on notched and unnotched cross-ply laminate. From this initial calibration, which takes relatively little time, it is possible to apply the model to a prediction of the dependence of fracture stress on notch size; to an understanding of the effects of laminate stacking sequence (within the same cross-ply family) on fracture stress; and to provide insight into the effects of thermal or load cycling history on fatigue damage-growth and residual or fatigue strength. The advantages and deficiencies of this modelling strategy are assessed, as well as the applicability of such a physical modelling approach to the predictive design and failure of composite materials in general.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008811721083
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  • 89
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    TEM Observation of the Zrc/Zro2 Interface Formed by Oxidation of Zrc Single Crystals (1998)
    Springer
    Journal of materials synthesis and processing 6 (1998), S. 191-195 
    Details
    ISSN: 1573-4870
    Keywords: Transmission electron microscopy observation ; interfacial microstructure ; oxidation ; ZrC ; cubic ZrO2 ; amorphous carbon film
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Microstructure at the interface of ZrC and ZrO2 formed by oxidation of a single crystal of ZrC with 100 faces at 600°C at an oxygen pressure of 2 kPa was observed by high-resolution transmission electron microscopy and scanning electron microscopy. The ZrO2 scale was shown to consist of two subscales, zones 1 and 2. The interfacial area in zone 1 was composed of regular lattice fringes corresponding to the 111, 200, and 220 lattices of cubic ZrO2 (c-ZrO2) crystallites 2 to 10 nm in size and an amorphous phase. The growth of crystallites occurred in zone 2, which visualized the interface of zones 1 and 2. Black thin films reminiscent of zone 1 were successfully separated, which were composed of amorphous carbon in which c-ZrO2 particles 2 to 20 nm in size were included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022673620322
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  • 90
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    Work Function of PbZrO3 (1998)
    Springer
    Journal of materials synthesis and processing 6 (1998), S. 335-338 
    Details
    ISSN: 1573-4870
    Keywords: PbZrO3 ; oxidation ; nonstoichiometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper reports the results of work function (WF) changes of undoped PbZrO3 during subsequent isothermal oxidation and reduction experiments at 500°C in the p(O2) range between 10 and 2.1 × 104 Pa. The results, obtained during three consecutive runs, indicate that heating at 500°C leads to continuous changes of surface properties resulting in a complex WF vs. time characteristic. The WF changes during the first oxidation are determined by a p(O2)-induced structural transition. The second oxidation results in two competitive processes, such as rapid increase of oxygen non-stoichiometry followed by a structural transition. Finally, the third oxidation is determined by changes of oxygen nonstoichiometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022603327570
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  • 91
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    Effect of Surface Preparation of Zirconia on its Reactivity with Oxygen (1998)
    Springer
    Journal of materials synthesis and processing 6 (1998), S. 373-377 
    Details
    ISSN: 1573-4870
    Keywords: Zirconia ; oxidation ; preparation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper reports surface electrical properties of zirconia studied using work function measurements in the temperature range 297–1173 K during oxidation. It was found that surface preparation procedures, such as grinding and polishing, result in a change of its reactivity with oxygen. The effects produced by the preparation can be removed during thermal treatment at 1473 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021820720142
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  • 92
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    Oxidation of Calcium Boride at High Temperature (1998)
    Springer
    Journal of materials synthesis and processing 6 (1998), S. 407-410 
    Details
    ISSN: 1573-4870
    Keywords: CaB6 ; oxidation ; weight gain ; calcium borate ; oxidation resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of CaB6 powders at high temperatures was investigated. The sample oxidized at 873 to 973 K for 25 hours exhibited weight gain with increasing oxidation temperature; the oxidation proceeded in accordance with the parabolic law during the initial oxidation stage. On the other hand, the weight gain of the sample oxidized at and above 1073 K for 4 h was approximately 80%; however even if the oxidation time was prolonged, an additional weight change did not occur. Based on the results of the X-ray diffraction analysis, calcium borate (CaB4O7) was present on the surface of the sample oxidized at 1073 K. The sample showed a good oxidation resistance at 1273 to 1373 K, because the surface film of calcium borate (CaB2O4) formed by oxidation acted as an oxidation resistant layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021880906030
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  • 93
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    On the Spectral Decomposition of Geopotential and Temperature Fields in the Stratosphere (1998)
    Springer
    Studia geophysica et geodaetica 42 (1998), S. 147-158 
    Details
    ISSN: 1573-1626
    Keywords: stratosphere ; spectral decomposition ; geopotential ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract The spectral structure of stratospheric fields (temperature and geopotential) is analyzed in terms of spherical harmonics in an effort to study the long-term behaviour of large-scale circulation patterns, as well as their connections to some extra-terrestrial effects. The daily meteorological data from the Free University Berlin (FUB) cover more or less the period 1976–1996 and are available for stratospheric levels of 50, 30 and 10 hPa. The analysis of the annual cycle of spherical harmonics is introduced, and changes of the principal wave components are compared with the changes in different sets of solar, geomagnetic and global circulation indices. This paper also deals with interannual variability with special emphasis on quasibiennial oscillations (QBO) and El Nino and Southern Oscillations (ENSO). Although this is a rather preliminary study, the decomposition of the stratospheric field into complex spherical harmonics seems to be a powerful technique in investigating and qualifying the response of the global atmospheric system to the changes in solar and geomagnetic activity, and in qualifying the relationships between large-scale circulation patterns and various oscillations such as QBO or ENSO, Using this technique, reasonable strong connections were found between wave numbers and interannual factors, and these connections were tentatively interpreted in terms of statistics. A very high degree of correlation was found for the four-trough shape of the polar vortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023305020573
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  • 94
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    Changes of Ozone Content at Middle Latitudes During Forbush Decreases in Cosmic Rays (1998)
    Springer
    Studia geophysica et geodaetica 42 (1998), S. 521-532 
    Details
    ISSN: 1573-1626
    Keywords: stratospere ; troposphere ; solar-terrestrial disturbances ; odd nitrogen ; temperature ; atmospheric dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract The variations of total ozone at Alma-Ata (43°N, 76 °E) and ozone profiles obtained by balloon sounding at Tateno (36°N, 140°E), Wallops Island (38°N, 75°W) and Cagliari (39°N, 9°E) in the periods of Forbush decreases (FD) in galactic cosmic rays have been analysed. A decrease of total ozone was observed in the initial stage of the FD and an increase 10–11 days later. The average total deviations calculated using the superposed epoch method for 9 FD events are equal to 30 D. U. in the positive and to −18 D. U. in the negative phase. The changes of average ozone profiles, associated with 26 FD events, are more significant in the lower stratosphere and upper troposphere. The decrease of the partial ozone pressure at a height of 12–15 km is about 30 υmb. These vertical variations of ozone coincide with the average changes of the respective temperature profiles. A cooling, on the average, of 3°C was observed at 12–15 km, and a heating of 4°C below this level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023301322428
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  • 95
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    Numerical prognosis for salinity profiles of future lakes in the opencast mine Merseburg-Ost (1998)
    Springer
    International journal of salt lake research 7 (1998), S. 235-260 
    Details
    ISSN: 1573-8590
    Keywords: groundwater ; Merseburg-Ost ; mine ; meromixis ; numerical model ; monimolimnion ; opencast ; physical limnology ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Salt-laden groundwater inflows have formed monimolimnia in developing lakes of the abandoned opencast lignite mine Merseburg-Ost, Central Germany. Water-levels are still rising. To predict the future status of the lakes, two numerical models were developed. One was designed to predict groundwater flows, the second included limnophysical processes. The models were run in parallel and data exchange between them was performed every 1 to 10 years of model time. A trial of a 100-years prognosis was done. The results of surface salinity, mixing depth, and salinity profile are given. A sensitivity analysis yielded indications for the accuracy of the prediction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009097319823
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    Potential salinity limitations on nitrogen fixation in sediments from Mono Lake, California (1998)
    Springer
    International journal of salt lake research 7 (1998), S. 261-274 
    Details
    ISSN: 1573-8590
    Keywords: cyanobacteria ; lake management ; Mono Lake ; nitrogen fixation ; salinity ; saline lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Mono Lake is a hypersaline alkaline lake in the high altitude Great Basin desert of eastern California. Algal productivity of the lake is nitrogen-limited, and a contributing source is derived from benthic nitrogen fixation. Lake level and salinity have fluctuated with natural climatic variations but have also been affected by the diversion of tributary streams. This research examines the influence of varied salinity and lake level on the potential for benthic nitrogen fixation in Mono Lake. A sediment-surface microbial mat community was exposed directly, and in acclimated cultures, to a range of Mono Lake salinities under anaerobic incubations and the activity of nitrogenase assayed by acetylene reduction. Activity was stimulated in light, but also occurred in darkness. Over an experimental salinity range from 50 to 150 g L−1 TDS, nitrogenase activity was reduced by 90 per cent, with the activity persisting at the highest salinity being attributable to dark fixation alone. Between a salinity of 50 g L−1, occurring in Mono Lake over 50 years ago, and 100 g L−1, nitrogenase activity was reduced by nearly half. Changes in the area of the littoral zone at varied lake levels also affect the total amount of potential benthic nitrogen fixation in the lake. An accounting of yearly inputs of nitrogen to Mono Lake suggests N2-fixation could contribute as much as 76–81 percent of the total. Inhibition of nitrogen fixation rates by increased salinity could limit the long-term nutrient supply and benthic primary productivity of this ecosystem.
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    URL: http://dx.doi.org/10.1007/BF02441878
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  • 97
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    Interactive effects of elevated carbon dioxide and growth temperature on photosynthesis in cotton leaves (1998)
    Springer
    Plant growth regulation 26 (1998), S. 33-40 
    Details
    ISSN: 1573-5087
    Keywords: carbohydrates ; elevated CO2 ; Gossypium hirsutum L. ; interaction ; photosynthesis ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cotton (Gossypium hirsutum L., cv DPL 5415) plants were grown in naturally lit environment chambers at day/night temperature regimes of 26/18 (T-26/18), 31/23 (T-31/23) and 36/28 °C (T-36/28) and CO2 concentrations of 350 (C-350), 450 (C-450) and 700 μL L-1 (C-700). Net photosynthesis rates, stomatal conductance, transpiration, RuBP carboxylase activity and the foliar contents of starch and sucrose were measured during different growth stages. Net CO2 assimilation rates increased with increasing CO2 and temperature regimes. The enhancement of photosynthesis was from 24 μmol CO2 m-2 s-1 (with C-350 and T-26/18) to 41 μmol m-2 s-1 (with C-700 and T-36/28). Stomatal conductance decreased with increasing CO2 while it increased up to T-31/23 and then declined. The interactive effects of CO2 and temperature resulted in a 30% decrease in transpiration. Although the leaves grown in elevated CO2 had high starch and sucrose concentrations, their content decreased with increasing temperature. Increasing temperature from T-26/18 to 36/28 increased RuBP carboxylase activity in the order of 121, 172 and 190 μmol mg-1 chl h-1 at C-350, C-450 and C-700 respectively. Our data suggest that leaf photosynthesis in cotton benefited more from CO_2 enrichment at warm temperatures than at low growth temperature regimes.
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    URL: http://dx.doi.org/10.1023/A:1006035517185
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  • 98
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    The relationship between electrical conductivity and selected macroinvertebrate communities in four river systems of south-west Victoria, Australia (1998)
    Springer
    International journal of salt lake research 7 (1998), S. 153-170 
    Details
    ISSN: 1573-8590
    Keywords: confounding parameters ; nutrients ; salinity ; survey design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract In order to relate macroinvertebrate fauna to electrical conductivity (EC), a survey of selected orders of macroinvertebrates was conducted in the Glenelg, Hopkins, Merri and Barwon River Catchments in south-west Victoria, Australia. The survey consisted of sampling 21 paired sites at confluences of streams. There was little difference between the in-stream habitat but there was a range of differences in EC between each of the paired sites. The dissimilarity of macroinvertebrate fauna between the paired sites was compared to the proportional difference in EC and other water quality variables (dissolved oxygen, water temperature, pH, NO2−N, NO3−N, PO4 and turbidity). This allowed the elimination of EC being confounded with geographical scale parameters and took into account other water quality parameters that may be confounded with EC. A positive relationship was found between the dissimilarity of the fauna at each of the two paired sites and the proportional difference in EC. No such relationship was found for any other measured water quality variable. The results of this survey show that macroinvertebrate community structure is associated with EC of the river systems investigated after eliminating large scale geographical patterns, in-stream habitat and the measured water quality parameters.
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    URL: http://dx.doi.org/10.1007/BF02441884
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  • 99
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    Potential salinity limitations on nitrogen fixation in sediments from Mono Lake, California (1998)
    Springer
    International journal of salt lake research 7 (1998), S. 261-274 
    Details
    ISSN: 1573-8590
    Keywords: cyanobacteria ; lake management ; Mono Lake〉/kwd〉 ; nitrogen fixation ; salinity ; saline lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Mono Lake is a hypersaline alkaline lake in the high altitude Great Basin desert of eastern California. Algal productivity of the lake is nitrogen-limited, and a contributing source is derived from benthic nitrogen fixation. Lake level and salinity have fluctuated with natural climatic variations but have also been affected by the diversion of tributary streams. This research examines the influence of varied salinity and lake level on the potential for benthic nitrogen fixation in Mono Lake. A sediment-surface microbial mat community was exposed directly, and in acclimated cultures, to a range of Mono Lake salinities under anaerobic incubations and the activity of nitrogenase assayed by acetylene reduction. Activity was stimulated in light, but also occurred in darkness. Over an experimental salinity range from 50 to 150 g L-1 TDS, nitrogenase activity was reduced by 90 per crnt, with the activity persisting at the highest salinity being attributable to dark fixation alone. Between a salinity of 50 g L-1, occurring in Mono Lake over 50 years ago, and 100 g L-1, nitrogenase activity was reduced by nearly half. Changes in the area of the littoral zone at varied lake levels also affect the total amount of potential benthic nitrogen fixation in the lake. An accounting of yearly inputs of nitrogen to Mono Lake suggests N2-fixation could contribute as much as 76–81 percent of the total. Inhibition of nitrogen fixation rates by increased salinity could limit the long-term nutrient supply and benthic primary productivity of this ecosystem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009001514449
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  • 100
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    Numerical prognosis for salinity profiles of future lakes in the opencast mine Merseburg-Ost (1998)
    Springer
    International journal of salt lake research 7 (1998), S. 235-260 
    Details
    ISSN: 1573-8590
    Keywords: groundwater ; Merseburg-Ost ; mine ; meromixis ; numerical model ; monimolimnion ; opencast ; physical limnology ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Salt-laden groundwater inflows have formed monimolimnia in developing lakes of the abandoned opencast lignite mine Merseburg-Ost, Central Germany. Water-levels are still rising. To predict the future status of the lakes, two numerical models were developed. One was designed to predict groundwater flows, the second included limnophysical processes. The models were run in parallel and data exchange between them was performed every 1 to 10 years of model time. A trial of a 100-years prognosis was done. The results of surface salinity, mixing depth, and salinity profile are given. A sensitivity analysis yielded indications for the accuracy of the prediction.
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    URL: http://dx.doi.org/10.1007/BF02441877
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