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  • 1
    Electronic Resource
    Electronic Resource
    The life and work of Rosemary Lowe-McConnell: pioneer in tropical fish ecology (1994)
    Springer
    Environmental biology of fishes 41 (1994), S. 67-80 
    Details
    ISSN: 1573-5133
    Keywords: Biography ; Behaviour ; Seasonality ; Predation ; Breeding ; Feeding ; Taxonomy ; Evolution ; Environmental fluctuations ; Tropics ; Africa ; South America
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Rosemary Lowe-McConnell is one of the pioneers of tropical fish ecology. During a colourful and eventful career spanning over 45 years, she has worked in the tropical waters of Africa and South America and contributed significantly to our understanding of the ecology, zoogeography, phenology, evolution and taxonomy of tropical fishes. She has also assisted countless young ichthyologists and fisheries scientists and stimulated ichthyology through her lucid books on fish ecology. She continues to play an active role in the promotion of ichthyology and ecology from her home in Sussex in the English countryside. A brief biography and tribute is given so that her contributions to tropical fish ecology can be more widely appreciated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02197835
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  • 2
    Electronic Resource
    Electronic Resource
    The life and work of Rosemary Lowe-McConnell: pioneer in tropical fish ecology (1994)
    Springer
    Environmental biology of fishes 41 (1994), S. 67-80 
    Details
    ISSN: 1573-5133
    Keywords: Biography ; Behaviour ; Seasonality ; Predation ; Breeding ; Feeding ; Taxonomy ; Evolution ; Environmental fluctuations ; Tropics ; Africa ; South America
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Rosemary Lowe-McConnell is one of the pioneers of tropical fish ecology. During a colourful and eventful career spanning over 45 years, she has worked in the tropical waters of Africa and South America and contributed significantly to our understanding of the ecology, zoogeography, phenology, evolution and taxonomy of tropical fishes. She has also assisted countless young ichthyologists and fisheries scientists and stimulated ichthyology through her lucid books on fish ecology. She continues to play an active role in the promotion of ichthyology and ecology from her home in Sussex in the English countryside. A brief biography and tribute is given so that her contributions to tropical fish ecology can be more widely appreciated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023803
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  • 3
    Electronic Resource
    Electronic Resource
    Community ecology and conservation of the fishes of the Okavango Delta, Botswana (1995)
    Springer
    Environmental biology of fishes 43 (1995), S. 109-119 
    Details
    ISSN: 1573-5133
    Keywords: Diversity ; Predictable ; Unpredictable ; Stability ; Eurytopic ; Stenotopic ; Seasonality ; Wetland ; Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The Okavango Delta is a large inland swamp in northern Botswana which receives an annual flood from the highlands of southern Angola. There are distinct fish taxocenes in the Okavango which can be separated from each other by the physical characteristics of the different habitat types with which they co-evolved. An account is given of the ecology and conservation of the fishes of the Okavango Delta. Their response to the annual flood regime, and the environmental factors that limit their distribution and abundance, are described. In the northern riverine floodplain and perennial swamp a higher species richness and ichthyomass was recorded than in the seasonal swamp and drainage rivers. Suggestions are made on the conservation of Okavango fishes taking into account the ecological characteristics of the Delta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002478
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  • 4
    Electronic Resource
    Electronic Resource
    Surface chemistry-controlled tribological behavior of silicon and diamond (1996)
    Springer
    Tribology letters 2 (1996), S. 173-187 
    Details
    ISSN: 1573-2711
    Keywords: tribometry ; high temperature ; single-crystal silicon ; polycrystalline silicon ; vacuum ; surface chemistry ; dangling bonds ; reconstruction ; adsorbates ; friction ; wear
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract SEM tribometric experiments were performed with Si(100) vs. Si(100) interfaces in mode-rate vacuum to 850°C. The results are compared with similar tests previously completed with fine-cauliflowered PCD (PCDfcf) mated against itself, and polished C(100)-textured polycrystalline diamond (PCDC(100)) sliding against Si(100). All data agree with a hypothesis connecting the thermal desorption of adsorbates and wear with the generation of dangling bonds on the sliding surfaces. Linking of the counterfaces by the free radicals appears to be the main cause of high adhesion and friction. The high friction can be drastically reduced by dissociative chemisorption of certain passivating gaseous species condensing at sufficiently low surface temperatures. Strong circumstantial evidence continues to mount for the incremental reduction in high temperature friction being caused by surface reconstruction. Deconstruction of the sliding surfaces and the reemergence of high friction eventually occurs on discontinued heating, until the adsorbates chemisorb on the cooled surfaces. There, the friction drops to a level determined by the characteristic shear strength of the interfaces and the wear-induced increase in the real area of contact. The maximum friction measured at high temperatures in vacuum, indicative of the most intensive interaction of dangling bonds at the interface, scaled only approximately with the 1.8 times strength of the C-C versus the Si-Si bonds. The 1.6 experimental ratio is lower than the theoretical, reflecting the broad distribution of dangling bond energies (densities of surface trap states) for PCD and even for polished Si(100). The wear rate of Si(100) sliding against itself is about four-orders-of-magnitude higher (~ 2 × 10-12 m3/(Nm)) than that of unpolished PCDfcf vs. itself (4 × 10-16 m3/(Nm)) or rough and unpolished PCDC(100) wearing its polished version (8.5 × 10-16 m3/(Nm)).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160974
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  • 5
    Electronic Resource
    Electronic Resource
    Atmospheric effects of friction, friction noise and wear with silicon and diamond. Part III. SEM tribometry of polycrystalline diamond in vacuum and hydrogen (1999)
    Springer
    Tribology letters 6 (1999), S. 103-112 
    Details
    ISSN: 1573-2711
    Keywords: polycrystalline diamond ; (100)-texture ; polishing ; tribometry ; vacuum ; hydrogen ; high temperatures ; friction ; friction noise ; noise reduction ; wear ; dangling bonds ; adsorbates ; desorption ; chemisorption ; re(de)construction ; tribocatalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this part III of a multi-part paper series, the results of additional SEM tribometric experiments are described, performed with polished, mostly C(100)-oriented polycrystalline CVD diamond film [PCDC(100) vs. PCDC(100)] counterfaces sliding in $$\sim 1 \times 10^{ - 5}$$ Torr and in 0.1–0.3 Torr partial pressures of pure hydrogen gas. These tests were completed under a 28 g (0.27 N) normal load, under standard and slow thermal ramping conditions at temperatures ranging from room temperature to 1000°C. The friction data were examined per the computer logging and analysis techniques described in part I. The treatment of the data is similar to that of Si in part II: the maximum and the average coefficients of friction (MAX.COF and COF) and their ratios (the friction noise FN) are employed to measure possible lubricative interaction of the diamond surfaces with rarefied hydrogen. The results indicate that excited species of molecular hydrogen enter into tribothermally catalyzed reactions not only with Si but with PCDC(100) surfaces as well. Similar to the behavior of Si, the most beneficial friction-reducing regime occurs in a temperature range just before the thermal desorption of adsorbates. The general magnitudes of MAX.COF, COF and the FN are significantly lower than those of the Si crystallinities, in both vacuum and $$P_{{\text{H}}_{\text{2}} }$$ . The wear rate of the PCDC(100) film characteristic of the standard thermal ramping test procedure performed mostly in $$P_{{\text{H}}_{\text{2}} }$$ is around $$4 \times 10^{ - 16} {\text{m}}^3 /({\text{Nm)}}$$ , in good agreement with the wear rate previously measured in vacuum for unpolished, fine-cauliflowered diamond films. The data indicate that smooth polycrystalline diamond is a significantly better bearing material for miniaturized moving mechanical assembly applications than Si.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019147304112
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  • 6
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019122915441
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  • 7
    Electronic Resource
    Electronic Resource
    Atmospheric effects of friction, friction noise and wear with silicon and diamond. Part II. SEM tribometry of silicon in vacuum and hydrogen (1999)
    Springer
    Tribology letters 6 (1999), S. 87-102 
    Details
    ISSN: 1573-2711
    Keywords: silicon ; tribometry ; vacuum ; hydrogen ; high temperatures ; friction ; friction noise ; noise reduction ; wear ; dangling bonds ; adsorbates ; desorption ; chemisorption ; re(de)construction ; tribothermal catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Scanning electron microscope (SEM) tribometric data on polycrystalline silicon (poly-Si) vs. poly-Si, Si(100) vs. Si(100) and Si(111) vs. Si(111) interfaces, obtained in $$\sim 1 \times 10^{ - 5}$$ Torr and in 0.2 Torr partial pressure of hydrogen gas ( $$P_{{\text{H}}_{\text{2}} }$$ ) from room temperature to 850°C, were performed under standard and much slower thermal ramping rates. The friction data were analyzed per the methodology described in part I of this paper series. The results indicate a highly beneficial friction- and wear-reducing regime within a relatively narrow thermal region. This desirable region coincides with some chemisorption of excited species of molecular hydrogen just before the mass thermal desorption of surface hydrides. These data represent the tribochemical equivalent of a method routinely used in electronics, whereby deep electron traps (dangling Si bonds) are passivated by baking in molecular hydrogen. The $$P_{{\text{H}}_{\text{2}} }$$ also exerts a moderating influence on the size of the friction noise at all test temperatures. However, the general level of friction beyond the beneficial thermal region is high. In parallel, the general wear rate of Si representative of the entire range of standard thermal ramping in both atmospheric environments is in the extremely high 10-12m3/(N m) range. Operating strictly in the beneficial, low-friction thermal regime resulted in a several orders-of-magnitude reduction in the wear rate over those measured under standard thermal ramping conditions. Although the results confirm previous findings that Si is not a good material of construction for miniaturized moving mechanical assemblies (e.g., microbearings and gears), there seems to be some limited possibility of gas-phase lubrication of Si micromechanisms with rarefied hydrogen at surface temperatures between 100 and 300°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019199320951
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  • 8
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019174932279
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  • 9
    Electronic Resource
    Electronic Resource
    Atmospheric effects of friction, friction noise and wear with silicon and diamond. Part I. Test methodology (1999)
    Springer
    Tribology letters 6 (1999), S. 79-86 
    Details
    ISSN: 1573-2711
    Keywords: SEM tribometry ; silicon ; polycrystalline diamond ; vacuum ; hydrogen ; high temperatures ; friction ; friction noise ; noise reduction ; data analysis ; characteristic frequency ; transducer ringing ; wear ; dangling bonds ; adsorbates ; desorption ; chemisorption ; re(de)construction ; tribothermal catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This multi-part paper series gives evidence of tribothermally catalyzed, lubricative interactions of low partial pressures of hydrogen, water vapor and oxygen with silicon and polycrystalline diamond employed as bearing materials in moving mechanical assemblies (e.g., miniaturized rotors, bearings and gears) of microelectromechanical systems. In part I a test methodology is described, whereby wide environmental range SEM-tribometric friction data are combined with friction noise analysis and applicable literature information to further assist in interpreting atomic-level interactions governing the macroscopic friction and wear behavior of Si and diamond. To further correlate the wear- and thermal desorption-induced generation, re(de)construction and adsorbate-passivated annihilation of dangling σ bonds with high and low adhesion and friction, previously generated average coefficient of friction (COF) values are complemented with the concept of the associated MAX.COF: the highest coefficient of kinetic friction gleaned from the raw computer-logged friction force data of each oscillatory cycle of an experiment. The MAX.COF/COF ratios are used as measures of the friction noise as a function of temperature and atmospheric environment. These quantities, sampled at the appropriate data logging rate to circumvent test machine-related vibrational disturbances, demonstrated signs of friction- and friction noise-reducing gas-phase interactions of dry hydrogen with silicon (part II) and diamond (part III). Future installments will deal with similar lubricative properties of low partial pressures of wet hydrogen and dry oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019151405021
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