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  • 1
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    Seawater carbonate chemistry and shell weights of Laternula elliptica, Yoldia eightsi, Nacella concinna and Liothyrella uva during experiments, 2009 (2009)
    PANGAEA
    In:  Supplement to: McClintock, James B; Angus, Robert A; Mcdonald, Michelle R; Amsler, Charles D; Catledge, Shane A; Vohra, Yogesh K (2009): Rapid dissolution of shells of weakly calcified Antarctic benthic macroorganisms indicates high vulnerability to ocean acidification. Antarctic Science, 21(5), 449-456, https://doi.org/10.1017/S0954102009990198
    Details
    Publication Date: 2024-03-15
    Description: Antarctic calcified macroorganisms are particularly vulnerable to ocean acidification because many are weakly calcified, the dissolution rates of calcium carbonate are inversely related to temperature, and high latitude seas are predicted to become undersaturated in aragonite by the year 2100. We examined the post-mortem dissolution rates of aragonitic and calcitic shells from four species of Antarctic benthic marine invertebrates (two bivalves, one limpet, one brachiopod) and the thallus of a limpet shell-encrusting coralline alga exposed to acidified pH (7.4) or non-acidified pH (8.2) seawater at a constant temperature of 4 C. Within a period of only 14-35 days, shells of all four species held in pH 7.4 seawater had suffered significant dissolution. Despite calcite being 35% less soluble in seawater than aragonite, there was surprisingly, no consistent pattern of calcitic shells having slower dissolution rates than aragonitic shells. Outer surfaces of shells held in pH 7.4 seawater exhibited deterioration by day 35, and by day 56 there was exposure of aragonitic or calcitic prisms within the shell architecture of three of the macroinvertebrate species. Dissolution of coralline algae was confirmed by differences in weight loss in limpet shells with and without coralline algae. By day 56, thalli of the coralline alga held in pH 7.4 displayed a loss of definition of the conceptacle pores and cracking was evident at the zone of interface with limpet shells. Experimental studies are needed to evaluate whether there are adequate compensatory mechanisms in these and other calcified Antarctic benthic macroorganisms to cope with anticipated ocean acidification. In their absence, these organisms, and the communities they comprise, are likely to be among the first to experience the cascading impacts of ocean acidification.
    Keywords: Alkalinity, total; Animalia; Antarctic; Aragonite saturation state; Benthic animals; Benthos; Bicarbonate ion; Brachiopoda; Calcification/Dissolution; Calcite saturation state; Calculated; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coast and continental shelf; DATE/TIME; EPOCA; EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis; European Project on Ocean Acidification; Experiment day; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Laboratory experiment; Laternula elliptica; Laternula elliptica, weight; Liothyrella uva; Liothyrella uva, weight; Mettler AJ100 balance (Mettler-Toledo); Mollusca; Nacella concinna; Nacella concinna, weight; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH meter (Fisher Model AB15); Polar; Salinity; Sample ID; Single species; Temperature, water; Titration; Yoldia eightsi; Yoldia eightsi, weight
    Type: Dataset
    Format: text/tab-separated-values, 5342 data points
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    DATA PANGAEA
  • 2
    Electronic Resource
    Electronic Resource
    In situ diagnostics of film thickness and surface roughness of diamond films on a Ti–6Al–4V alloy by optical pyrometry (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 181-183 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thickness and surface roughness of diamond films grown on a Ti–6Al–4V alloy in a microwave plasma reactor was measured in situ using optical pyrometry. The growing film results in oscillations of the apparent temperature with time, which can be explained by interference effects caused by reflections from the film/air and film/substrate interfaces. The equation governing the transmittance of the diamond/metal system has been derived by taking into account the complex index of refraction of an absorbing substrate. The apparent temperature was modeled using this relation for the transmittance in order to extract the time dependence of film thickness, surface roughness, and the true temperature of the substrate. The growth rate was observed to exhibit two regimes: an initial period of slowly increasing growth followed by a growth rate that was about 50% higher. The surface roughness increased at a nearly uniform rate but quickly reached a saturation roughness for long deposition times (high surface roughness). The limitation of the model for films in the high surface roughness regime is discussed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121748
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  • 3
    Electronic Resource
    Electronic Resource
    High density plasma processing of nanostructured diamond films on metals (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 6469-6471 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new regime is reported for synthesis of nanostructured diamond films on Ti–6Al–4V alloy and molybdenum substrates using microwave plasma chemical vapor deposition (CVD) at high pressure (125 Torr) and high methane feed-gas concentration (5%–15% in a balance of hydrogen). These films are shown to be predominantly comprised of diamond nanocrystallites in a matrix of tetrahedral amorphous carbon. In contrast to standard CVD conditions, the high density plasma results in adhered films on the metal substrates even at substrate temperatures of 850 °C. These films are also significantly smoother than conventionally processed CVD diamond films and have a rms surface roughness of about 50 nm. The average grain size of these nanocrystalline diamond films is 13 nm as determined from x-ray diffraction data and the hardness of the films as determined from nanoindentation data is 90% that of natural diamond. Micro-Raman studies using 458 and 647.1 nm excitation indicate an increasing tetrahedral amorphous carbon content with increasing methane feed-gas concentration. The adhesion and mechanical properties of these films makes them attractive for a variety of tribological applications. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368975
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanical properties and quality of diamond films synthesized on Ti–6Al–4V alloy using the microwave plasmas of CH4/H2 and CO/H2 systems (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 198-204 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Microwave plasma-enhanced chemical vapor deposition was used to grow diamond films on Ti–6Al–4V alloy using various gas phase precursors. The results of four types of experiments with different gas mixtures are compared: (1) 2% CH4 in H2; (2) initial saturation of 5% CH4 in H2 followed by 2% CH4 in H2; (3) a CO-rich mixture with a CO:H2 ratio of 8; and (4) a hybrid mixture of 2% CH4 in H2 followed by a CO:H2 ratio of 8. The substrate temperature during deposition with CH4/H2 mixtures was between 715 and 810 °C, and was between 550 and 600 °C when CO/H2 mixtures were used. Optical emission spectroscopy was used to monitor the excited gas-phase species in the plasma. The films were characterized by micro-Raman spectroscopy, glancing-angle x-ray diffraction, and nanoindentation. The films grown with the type (1) mixture often exhibited good quality with high hardness (70 GPa) but suffered from poor adhesion to the substrate. The films grown with the type (2) mixture were of slightly lower quality and hardness (58 GPa) but exhibited better adhesion. The films produced from the type (3) mixture were adhered, but exhibited very low growth rates and low hardness (18 GPa). Finally, the films produced from the hybrid type (4) mixture were of poor quality and suffered from poor adhesion to the substrate. The differences in interfacial phases and mechanical properties for each film are discussed and the usefulness of each gas mixture for the diamond growth is evaluated. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366673
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  • 5
    Electronic Resource
    Electronic Resource
    High density plasma processing of diamond films on titanium: Residual stress and adhesion measurements (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 7053-7058 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High density plasma processing of diamond films on titanium was carried out by microwave plasma chemical vapor deposition. The deposited films were characterized by Raman spectroscopy and thin film x-ray diffraction. We measure a residual compressive stress of 3.5±1.0 GPa which is lower than that obtained in previous studies. A measure of the film adherence to the titanium substrates was obtained by examining micro-Raman spectra near Brale C indentations. Using a model for biaxially stressed polycrystalline diamond films, it is determined that as much as 7.8 GPa can be sustained in the film before delamination occurs. Our experimental results are compared to earlier adhesion data of diamond on titanium. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360409
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of nitrogen addition on the microstructure and mechanical properties of diamond films grown using high-methane concentrations (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 698-700 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the microstructure and mechanical properties of diamond films grown using varying nitrogen additions to a plasma with a high-CH4 fraction of 15% (in hydrogen) and an operating pressure of 125 Torr. Films were grown at N2/CH4 ratios ranging from 0 to 0.30 by fixing the CH4 flow rate and changing only the N2 flow rate. With increasing nitrogen addition, we observe an increase in intensity and a decrease in the full width at half maximum (FWHM) of the Raman band at 1550 cm−1, while the crystalline diamond peak at 1332 cm−1 decreases in intensity and increases in the FWHM. X-ray diffraction confirms that the film crystallinity and diamond grain size decrease rapidly with increasing nitrogen additions up to a N2/CH4 ratio of 0.10, but then do not change significantly above this ratio. A similar trend is observed for film surface roughness. In addition, we find from indentation testing that all films exhibit high hardness values ranging from 70 to 90 GPa and that the toughness of the films improves with increasing nitrogen addition. Optical emission spectroscopy reveals that an increase in CN species relative to C2 in the plasma is responsible for the formation of tetrahedral amorphous carbon (indicated by the Raman band at 1550 cm−1). © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370787
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  • 7
    Electronic Resource
    Electronic Resource
    Nanoindentation hardness and adhesion investigations of vapor deposited nanostructured diamond films (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5347-5352 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of changing the N2/CH4 feedgas ratio on the structure and mechanical properties of microwave plasma chemical vapor deposited diamond films grown on Ti–6Al–4V alloy substrates was investigated. The relative concentration of CH4 and N2 (in a balance of H2) was shown to strongly influence film structure, hardness, and adhesion. For high CH4 concentration (15% by volume), nanostructured diamond films with roughness magnitudes of 15–30 nm, good adhesion and a high hardness value of 90 GPa was obtained. A distinct correlation was found between the nanoindentation hardness of the deposited film and the N2/CH4 ratio in the plasma, as well as a correlation of hardness to the ratio of the Raman peak intensities (1332 and 1555 cm−1). Scratch adhesion testing of nanostructured diamond films showed delamination at a critical force of 33 N using acoustic emission techniques. These results demonstrate that nanostructured diamond films can be tailored on metallic surfaces with hardness ranging from 10 GPa (medium-hard) to 100 GPa (superhard) and may be considered for wear resistant applications such as in the design of articulating medical implant devices. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1464233
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  • 8
    Electronic Resource
    Electronic Resource
    Gas-phase thermodynamic models of nitrogen-induced nanocrystallinity in chemical vapor-deposited diamond (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2550-2552 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gas-phase thermodynamic equilibrium calculations involving H2/CH4/N2 mixtures were performed to investigate the chemical interactions leading to nitrogen-induced nanocrystallinity in microwave plasma chemical vapor deposition of diamond films. The strong influence of the CN radical in causing nanocrystallinity is confirmed by the correlation of its modeled composition in the gas phase with the degree of nanocrystallinity as determined experimentally for diamond films grown with different N2 additions. For a given CH4 feedgas concentration, there exists a critical N2 feedgas concentration, above which the change in the CH3/CN ratio is minimal and further induced nanocrystallinity is diminished. This is verified experimentally where it is observed that the same critical N2 feedgas concentration exists, above which a further decrease in diamond crystallinity and surface roughness of the grown diamond films is minimal. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1467618
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  • 9
    Electronic Resource
    Electronic Resource
    Nanoindentation and x-ray diffraction studies of pressure-induced amorphization in C-70 fullerene (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 851-853 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have carried out high-pressure studies on a C-70 fullerene sample in a diamond anvil cell to 46 GPa at room temperature. Synchrotron energy dispersive x-ray diffraction studies were carried out to monitor the irreversible amorphization transformation followed by nanoindentation studies of the pressure-quenched samples. Micro-Raman studies indicate broad bands at 1570 and 1422 cm−1 indicative of an amorphous phase with a mixture of sp2- and sp3-bonded carbon. Nanoindentation studies on the quenched amorphous phase shows an elastic loading behavior with a hardness of 18 GPa, which is 2–3 times that of the surrounding steel gasket. Our results conclusively establish that the hard carbon phases can be produced from C-70 fullerene by application of pressure at room temperature. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1306913
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  • 10
    Electronic Resource
    Electronic Resource
    Nanoindentation hardness and atomic force microscope imaging studies of pressure-quenched zirconium metal (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 3568-3570 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have carried out mechanical property measurements on zirconium metal compressed in a diamond anvil cell to 19 GPa at room temperature with subsequent quenching to room pressure. The irreversible transformation from the ambient hexagonal-close-packed phase to the simple hexagonal ω phase (AlB2 structure) is confirmed by synchrotron energy dispersive x-ray diffraction followed by nanoindentation of the pressure-quenched sample. We document an 80% increase in hardness as a consequence of the pressure-induced transformation to the ω phase at room temperature. This is a large increase for a metallic phase transformation and can be attributed to the presence of sp2-hybrid bonds forming graphite-like nets in the (0001) plane of the AlB2 structure. Atomic force microscopy of the indents shows that a plastic deformation of 2 μm in depth was achieved with a force of 200 mN. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1329632
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