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  • 1
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    Ocean deoxygenation and zooplankton: Very small oxygen differences matter (2019)
    American Association for the Advancement of Science
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Science Advances, 4(12), (2018): eaau5180. doi: 10.1126/sciadv.aau5180.
    Description: Oxygen minimum zones (OMZs), large midwater regions of very low oxygen, are expected to expand as a result of climate change. While oxygen is known to be important in structuring midwater ecosystems, a precise and mechanistic understanding of the effects of oxygen on zooplankton is lacking. Zooplankton are important components of midwater food webs and biogeochemical cycles. Here, we show that, in the eastern tropical North Pacific OMZ, previously undescribed submesoscale oxygen variability has a direct effect on the distribution of many major zooplankton groups. Despite extraordinary hypoxia tolerance, many zooplankton live near their physiological limits and respond to slight (≤1%) changes in oxygen. Ocean oxygen loss (deoxygenation) may, thus, elicit major unanticipated changes to midwater ecosystem structure and function.
    Description: We thank the captain and crew of the R/V Sikuliaq (University of Alaska) and Scripps Institution of Oceanography for additional technical services. Thanks also to D. Ullman and D. Casagrande for Wire Flyer assistance; C. Matson and J. Calderwood for MOCNESS upgrades; S. Gordon (professional photographer, Open Boat Films LLC) for the photographs and movies; and A. Dymowska, J. Ivory, Y. Jin, J. McGreal, and N. Redmond for help at sea. Funding: Funding was provided by the NSF grants OCE1459243 (to K.F.W., C.R., and B.A.S.), OCE1458967 (to C.D.), DGE1244657 (to M.A.B.), and OCE1460819 (URI REU SURFO program to S.R.) plus funding from our respective institutions. Author contributions: K.F.W., B.A.S., C.R., and C.D. conceived the project. K.F.W. led the writing effort, with substantial contributions from all the authors. K.F.W. directed the MOCNESS component including zooplankton abundance and biomass quantification. B.A.S. directed the metabolic experiments and Tucker trawls. C.R. directed the Wire Flyer work. B.A.S., C.D., K.A.S.M., and M.A.B. developed the MI models. D.O., C.T.S., D.M., and S.R. processed and analyzed the zooplankton data. T.J.A. processed the MOCNESS hydrographic data. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Extensive files of continuous hydrographic data from transects are available from C.R. (Wire Flyer) and K.F.W. (MOCNESS). Additional data related to this paper may be requested from the authors.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
    Electronic Resource
    Electronic Resource
    The decomposition of C60 on nickel clusters (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 2479-2485 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The adsorption of C60 on nickel clusters Nin in the n=8–31 size range is studied at elevated temperatures. Above 800 °C, decomposition of C60 is seen on clusters containing oxide impurities by the loss of CO and/or CO2 molecules. The extent of decomposition depends on cluster size and C60 coverage, which affect the charging of the metal core by electron transfer from the metal to the C60. Both decreased cluster size and increased C60 coverage reduce the electron transfer per C60 molecule, weakening the C60–Nin bond and decreasing the rate of decomposition. In spite of this effect, C60 appears to decompose more readily on small nickel clusters than on bulk nickel surfaces. While decomposition is only observed for clusters having adsorbed O atoms, the oxygen may actually inhibit decomposition by withdrawing electronic charge from the metal, likewise weakening the C60–Nin bond. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480813
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  • 3
    Electronic Resource
    Electronic Resource
    The structure of Ni39 (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 10207-10216 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The geometrical structure of Ni39 is probed via molecular adsorption of nitrogen on its surface. Nitrogen uptake patterns are determined at various reaction temperatures, and the results are interpreted in terms of the number and nature of nitrogen binding sites on possible structures. It is found that an adsorbate-induced isomerization occurs at partial nitrogen coverage, but that at saturation a reverse isomerization returns the cluster to its initial structure. The two lowest energy structures calculated by Wetzel and DePristo [T. L. Wetzel and A. E. DePristo, J. Chem. Phys. 105, 572 (1996)] are completely consistent with the observed saturation and isomerization behavior. The structures consist of atom caps packed around a central pentagonal bipyramid, and reflect a marked change from the octahedral structure determined earlier for Ni38.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.477715
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  • 4
    Electronic Resource
    Electronic Resource
    Reactions of Ni38 with N2, H2, and CO: Cluster structure and adsorbate binding sites (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 1861-1871 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The gas-phase reactions of nitrogen, hydrogen, and carbon monoxide with Ni38 are studied as a function of reagent pressure at several reaction temperatures. Saturation coverage of the cluster is found at Ni38(N2)24, Ni38H36, and Ni38(CO)36. These saturation levels are consistent with the metal core of the ligated cluster having the structure of a truncated octahedron in each case. An alternate fcc structure derived from a 40-atom truncated tetrahedron is consistent with the nitrogen data, but not with the hydrogen or carbon monoxide results. In addition, the nitrogen uptake data indicate that the bare Ni38 cluster also has the structure of a truncated octahedron or possibly a deformed truncated octahedron. There is no indication that Ni38 has an icosahedral or polyicosahedral structure. The nature of the binding of the three reagents to the cluster is discussed. Evidence is presented that CO initially binds to atop sites, but following saturation of these sites a local rearrangement to bridge sites occurs that allows an increase in coverage to the observed saturation at Ni38(CO)36. At high reagent pressures all three reagents cause adsorbate-induced structural changes to isomers that bind more ligands and whose structures have yet to be determined. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.474536
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  • 5
    Electronic Resource
    Electronic Resource
    The binding of CO to nickel clusters. I. Determination of saturation coverages (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 3384-3393 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The reactions of small nickel clusters Nin (n=3–60) with carbon monoxide are studied in a gas-phase flow-tube reactor. Cluster coverage is determined as a function of CO pressure at temperatures between −160 and 20 °C. The reactions are kinetically controlled under these conditions, but the CO uptake is characterized by a transition from a fast kinetics to a slow kinetics process. Sticking probabilities in the fast kinetics region are near unity at low temperature. The coverage at the transition is consistent with random filling of the cluster surface with van der Waals CO molecules in a standing up configuration with the carbon end toward the metal. Higher coverages in most cases are a consequence of changes in nickel cluster structure to more open ones having larger surface areas. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480920
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  • 6
    Electronic Resource
    Electronic Resource
    The binding of CO to nickel clusters. II. Structural implications and comparisons with electron counting rules (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 3394-3407 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The saturation levels of small nickel clusters Nin (n=2–20) with CO are determined. Modeling of the CO-covered clusters shows that in almost all cases saturation is governed by the geometrical sizes of the nickel clusters and the van der Waals size of the CO molecules. While electron counting rules, along with an assumed cluster structure, can predict saturation levels, the predictions generally overestimate the levels based on geometry. In the case of the smallest clusters (n≤13), CO adsorption appears to cause changes in structure to more open ones that result in increased adsorption, giving coverages close to the electron counting rule predictions for the bare cluster geometries. Larger clusters, with internal metal atoms, seem to be more resistant to structural changes. Comparisons with earlier studies of nickel cluster positive and negative ions are made and the significance of a short reaction time scale on the nature of the reaction products is discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480499
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  • 7
    Electronic Resource
    Electronic Resource
    The thermodynamics of nitrogen adsorption on nickel clusters: Ni19–Ni71 (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 3731-3739 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Equilibrium constants for the chemisorption reactions of molecular nitrogen with nickel clusters Nin have been determined as a function of temperature for n=19 to 71. Van't Hoff analysis of the data yields standard-state changes in reaction enthalpy and entropy. These changes are related to what is known about nickel cluster structure and the nature of the cluster–N2 interaction. In general, the adsorption energy is highest for the smallest clusters studied, reaching values twice those for N2 adsorption on bulk nickel surfaces. In many cases, there is a correlation between enthalpy and entropy: high adsorption energy is accompanied by a large change in entropy, and vice versa. These effects are discussed in terms of the configurational entropy of reaction and the frequencies of the frustrated translational and rotational motions of the adsorbed N2 molecules. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475779
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  • 8
    Electronic Resource
    Electronic Resource
    The reaction of manganese clusters and manganese cluster carbides with hydrogen: The Mn–CH3 bond energy (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 3531-3536 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Manganese clusters are formed by laser vaporization in an inert gas condensation source cooled to −160 °C. A pure manganese target is used as well as a manganese target containing 2 mol % carbon. The clusters are reacted with hydrogen both in the region of cluster growth and in a flow-tube reactor (FTR) downstream of the cluster source. The reactions, both with hydrogen atoms in the cluster growth region and dissociative chemisorption of H2 in the FTR, result in hydrogen atoms bound to the clusters, except that for Mn15 and smaller clusters the H atoms are unstable against H2 desorption. Above Mn15 stable hydrides are formed, but the rate of reaction in the FTR varies considerably with cluster size. This abrupt change in the ability to bind hydrogen may reflect a significant change in the character of the bonding within the cluster, perhaps from van der Waals to metallic. MnnC clusters readily react with hydrogen for n(approximately-greater-than)6 to form MnnCH2. Further reactivity generally follows the pattern of the bare clusters, suggesting that the two hydrogen atoms on MnnCH2 are bound to the carbon. Under certain conditions a large intensity of MnnCH3 species (n≥1) is seen. From these results and earlier reports of reactions of Mn with various hydrocarbons, an energy of 1.21±0.09 eV is determined for the Mn–CH3 bond. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471058
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  • 9
    Electronic Resource
    Electronic Resource
    Umbilical metastasis from squamous carcinoma of the cervix (1982)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 89 (1982), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1982.tb04669.x
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  • 10
    Electronic Resource
    Electronic Resource
    The reaction of iron clusters with ammonia. I. Compositions of the ammoniated products and their implications for cluster structure (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 6260-6272 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Studies are described of the chemisorption of ammonia on isolated neutral iron clusters Fen for 2≤n≤165. Clusters are generated by laser vaporization in a continuous-flow-tube reactor, and reaction products are detected by laser-ionization time-of-flight mass spectrometry. Ammonia is found to chemisorb nondissociatively on cluster surfaces on the 1 ms time scale of these experiments. Measurements of ammonia uptake provide information on adsorption kinetics and on the number and nature of the binding sites. The ammonia binding energy is found to decrease with increasing cluster coverage. For chemically saturated clusters, the ratio of adsorbed NH3 molecules to surface iron atoms is found to decrease with increasing cluster size, going from 〉1/3 for small clusters to 〈1/3 for n〉100. Ammonia chemisorption is accompanied by a large decrease in cluster ionization potentials, as much as 2 eV for saturated clusters. At sufficiently high exposure the beginning of the formation of a second, physisorbed layer of molecules is seen. Detailed measurements of product composition under different exposure conditions give evidence for numerous changes in cluster structure throughout the growth sequence from small to large clusters. Often these structural changes involve particularly stable reaction products. Evidence for the existence of metastable structures is presented. Several possibilities for cluster structure are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454465
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