The dislocation geometry of interphase boundaries

Knowles, K. M.

doi:10.1080/01418618208236943

Cited by 61 publications

(29 citation statements)

References 23 publications

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“…Denitri®cation, like N 2 ®xation, is a critical bottleneck process in mat N cycling, as it represents the`loss' of N via conversion of NO 3 À to N 2 gas (Knowles, 1982;Hattori, 1983). Denitri®ers include taxonomically and physiologically diverse facultative anaerobic bacteria genera; Pseudomonas and Thiobacillus are often cited.…”

Section: Microbial Mats As Model Consortial Systemsmentioning

confidence: 99%

Cyanobacterial–bacterial mat consortia: examining the functional unit of microbial survival and growth in extreme environments

Paerl

Pinckney

Steppe

2000

Environmental Microbiology

254

167

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Cyanobacterial–bacterial consortial associations are taxonomically complex, metabolically interactive, self‐sustaining prokaryotic communities representing pioneer and often the only biota inhabiting extreme aquatic and terrestrial environments. Laminated mats and aggregates exemplify such communities. The fossil record indicates that these associations represent the earliest extant inhabitants and modifiers (i.e. anoxic to oxic conditions) of the Earth's biosphere. Present‐day consortia flourish in physically and chemically stressed environments, including nutrient‐deplete, hypersaline, calcified, desiccated and high‐irradiance ecosystems ranging from the tropics to polar regions. Consortial members exhibit extensive metabolic diversification, but have remained structurally simple. Structural simplicity, while advantageous in countering environmental extremes, presents a ‘packaging problem’ with regard to compartmentalizing potentially cross‐inhibitory aerobic versus anaerobic growth processes. To circumvent these metabolic constraints, phototrophic cyanobacteria and microheterotrophs orient along microscale chemical (i.e. O2, pH, Eh) gradients to meet and optimize the biogeochemical processes (C, N, S cycling) essential for survival, growth and the maintenance of genetic diversity, needed to sustain life. Microscale ecophysiological, analytical, molecular (immunological and nucleic acid) techniques have helped to develop a mechanistic basis for understanding consortial growth and survival under extreme environmental conditions on Earth. Consortia are ideal model systems for developing a process‐based understanding of the structural and functional requirements for life in extreme environments representative of the Earth's earliest biosphere and possibly other planets.

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Section: Microbial Mats As Model Consortial Systemsmentioning

confidence: 99%

Cyanobacterial–bacterial mat consortia: examining the functional unit of microbial survival and growth in extreme environments

Paerl

Pinckney

Steppe

2000

Environmental Microbiology

254

167

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“…The standard analysis method described in [51] may be used to calculate the spacing and line directions of interface misfit dislocations such that they account for the dislocation content described by Eqn. 5.…”

Section: Iiia Misfit Dislocation Configurationmentioning

confidence: 99%

Structure, shear resistance and interaction with point defects of interfaces in Cu–Nb nanocomposites synthesized by severe plastic deformation

2011

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We use atomistic modeling to investigate the shear resistance and interaction with point defects of a Cu-Nb interface found in nanocomposites synthesized by severe plastic deformation. The shear resistance of this interface is highly anisotropic: in one direction shearing occurs at stresses below 1200MPa while in the other it does not occur at all. The binding energy of vacancies, interstitials, and He impurities to this interface depends sensitively on the binding location, but there is no point defect delocalization nor does this interface contain any constitutional defects. These behaviors are markedly dissimilar from a different Cu-Nb interface found in magnetron sputtered composites. The dissimilarities may, however, be explained by quantitative differences in the detailed structure of these two interfaces.* Corresponding author: demkowicz@mit.edu 617-324-6563 MIT, room 4-142 77 Massachusetts Ave.

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“…This method was modified by Ecob and Ralph 53 and Knowles and Smith. 47 The optimum interfaces from these parameter approaches are usually parallel to the POPs, [52][53][54] as one or more types of dislocations will be added to any vicinal interface, causing the value of a parameter to increase. These optimum interfaces are singular interfaces within the dislocation rings in Figure 3.…”

Section: Links Between Modelsmentioning

confidence: 99%

Faceted interfaces: a key feature to quantitative understanding of transformation morphology

Zhang

Dai

2016

npj Comput Mater

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Faceted interfaces are a typical key feature of the morphology of many microstructures generated from solid-state phase transformations. Interpretation, prediction and simulation of this faceted morphology remain a challenge, especially for systems where irrational orientation relationships (ORs) between two phases and irrational interface orientations (IOs) are preferred. In terms of structural singularities, this work suggests an integrated framework, which possibly encompasses all candidates of faceted interfaces. The structural singularities are identified from a matching pattern, a dislocation structure and/or a ledge structure. The resultant singular interfaces have discrete IOs, described with low-index g's (rational orientations) and/or Δg's (either rational or irrational orientations). Various existing models are grouped according to their determined results regarding the OR and IO, and the links between the models are clarified in the integrated framework. Elimination of defect types as far as possible in a dominant singular interface often exerts a central restriction on the OR. An irrational IO is usually due to the elimination of dislocations in one direction, i.e., an O-line interface. Analytical methods using both three-dimensional and two-dimensional models for quantitative determinations of O-line interfaces are reviewed, and a detailed example showing the calculation for an irrational interface is given. The association between structural singularities and local energy minima is verified by atomistic calculations of interfacial energies in fcc/bcc alloys where it is found that the calculated equilibrium cross-sections are in a good agreement with observations from selected alloys.

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The dislocation geometry of interphase boundaries

Cited by 61 publications

References 23 publications

Cyanobacterial–bacterial mat consortia: examining the functional unit of microbial survival and growth in extreme environments

Cyanobacterial–bacterial mat consortia: examining the functional unit of microbial survival and growth in extreme environments

Structure, shear resistance and interaction with point defects of interfaces in Cu–Nb nanocomposites synthesized by severe plastic deformation

Faceted interfaces: a key feature to quantitative understanding of transformation morphology

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