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Open Access Publications from the University of California

Scholarly Works (2 results)

  • Article
  • Peer Reviewed
The Proceedings of the International Plant Nutrition Colloquium XVI (2009)

Two trials established at contrasting sites with different soil nutrient and water availability at Balmoral in Canterbury and Aniseed Valley in Nelson, New Zealand were examined to (1) quantify the genotypic variation in foliar nutrient concentrations, δ13C and δ15N of 45 Pinus radiata genotypes in relation to tree growth and (2) determine the genotype by environment interactions for these traits. Significant genotypic differences were found in foliar nutrient concentrations, δ13C and δ15N. There were significant differences among the genotypes in tree growth, with some genotypes performing consistently better and some poorer across sites. The interaction of site by genotype was also highly significant for all growth variables and significant for some foliar nutrients (Ca, Mg and Mn). Significant correlations were found between growth variables and foliar nutrient concentrations or δ15N of the 45 genotypes at both sites. Stepwise multiple regression analyses of tree growth variables against foliar nutrient concentrations showed P, Fe, Mg, K, S and N at Aniseed Valley and δ15N, N, Mn and S at Balmoral contributed significantly (P < 0.05) to the models, respectively. This study indicated that foliar nutrient concentration and δ13C could be used as the potential indicators for screening Pinus radiata genotypes with better growth under the nutrient and moisture limiting conditions in New Zealand.

    Cover page: Genotypic variation in foliar nutrient concentrations, carbon and nitrogen isotope compositions in relation to tree growth of Pinus radiata
    • Article
    • Peer Reviewed
    LBL Publications (2019)
    Atomic disordering in materials alters their physical and chemical properties and can subsequently affect their performance. In complex ceramic materials, it is a challenge to understand the nature of structural disordering, due to the difficulty of direct, atomic-scale experimental observations. Here we report the direct imaging of ion irradiation-induced antisite defects in Mn+1AXn phases using double CS-corrected scanning transmission electron microscopy and provide compelling evidence of order-to-disorder phase transformations, overturning the conventional view that irradiation causes phase decomposition to binary fcc-structured Mn+1Xn. With the formation of uniformly distributed cation antisite defects and the rearrangement of X anions, disordered solid solution γ-(Mn+1A)Xn phases are formed at low ion fluences, followed by gradual transitions to solid solution fcc-structured (Mn+1A)Xn phases. This study provides a comprehensive understanding of the order-to-disorder transformations in Mn+1AXn phases and proposes a method for the synthesis of new solid solution (Mn+1A)Xn phases by tailoring the disorder.
      Cover page: Disorder in Mn+1AXn phases at the atomic scale
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