A unified viscoplastic model for high temperature low cycle fatigue of service-aged P91 steel

The finite element (FE) implementation of a hyperbolic sine unified cyclic viscoplasticity model is presented. The hyperbolic sine flow rule facilitates the identification of strain-rate independent material parameters for high temperature applications. This is important for the thermo-mechanical fatigue of power plants where a significant stress range is experienced during operational cycles and at stress concentration features, such as welds and branched connections. The material model is successfully applied to the characterisation of the high temperature low cycle fatigue behavior of a service-aged P91 material, including isotropic (cyclic) softening and nonlinear kinematic hardening effects, across a range of temperatures and strain-rates

Parameters defining the logistic model of fungal growth.

<p><i>L</i>. <i>theobromae</i> strain 2334 was cultivated in shake flasks of 100 mL, 250 mL and 500 mL in the presence of KNO₃ as nitrogen source.</p

Parameters defining the Leudiking and Piret model in shake flasks of <i>L</i>. <i>theobromae</i> strain 2334 of volumes of 100 mL, 250 mL and 500 mL and in the presence of KNO₃ as nitrogen source.

<p>Parameters defining the Leudiking and Piret model in shake flasks of <i>L</i>. <i>theobromae</i> strain 2334 of volumes of 100 mL, 250 mL and 500 mL and in the presence of KNO₃ as nitrogen source.</p

Parameters defining the logistic model of JA-production.

<p><i>L</i>. <i>theobromae</i> strain 2334 was cultivated in shake flasks of 100 mL, 250 mL and 500 mL in the presence of KNO₃ as nitrogen source.</p

UHPLC-ESI-QTOF-MS analysis of OPC-4 and 11/12-hydroxy-JA formed by <i>L</i>. <i>theobromae</i> strain 2334.

<p>The fungus was cultivated in medium supplemented with KNO₃ for 9 days (d). After extraction compounds of the culture filtrate were analyzed via UHPLC-ESI-QTOF-MS. Shown are high resolution MS/MS spectra (negative ionization mode; collision energy 10 eV) of (<b>A</b>) OPC-4 ([M-H]^- 237.1512, RT 6.14 min) and (<b>B</b>) 11/12-hydroxy-JA ([M-H]^- 225.1120, RT 4.02 min). Proposed fragmentation is shown as inset. Abbreviations: JA, jasmonic acid; OPC-4, 3-oxo-2-(pent-2-enyl)-cyclopentane-1-butanoic acid.</p

Average concentrations of plant secondary metabolites, indole-3-carboxylic acid (ICA) and salicylic acid (SA) in the culture medium of <i>L</i>. <i>theobromae</i> strain 2334.

<p>Culture filtrate was obtained after 9 days of growth in medium containing KNO₃ as nitrogen source and cultivated as surface culture of different volumes: 100 mL, 250 mL and 500 mL. An additional experiment was performed as surface culture of 250 mL using medium with NH₄NO₃ as nitrogen source (250 ml-NH₄NO₃). Data are means ± standard deviations of three replicates. Detection limit for SA was 1x10^-4 mg/L at a signal to noise ratio of three.</p

UHPLC-ESI-QTOF-MS analysis of the main metabolites in the culture medium of <i>L</i>. <i>theobromae</i> strain 2334.

<p><i>L</i>. <i>theobromae</i> strain 2334 was cultivated in medium supplemented with KNO₃ for 9 d. After extraction, compounds of the culture filtrate were analyzed via UHPLC-ESI-QTOF-MS. Shown is a total ion chromatogram (<b>A</b>), as well as high resolution MS/MS-spectra (negative ionization mode; collision energy 10 eV) of different compounds (<b>B-H</b>). Proposed structures and fragmentations are shown as inset for each spectrum. The following compounds were identified: dihydroxy-dihydro-JA ([M-H]^- 243.1212, RT 3.40 min) <b>(B</b>), 8-hydroxy-JA ([M-H]^- 225.1120, RT 3.78 min) (<b>C</b>), hydroxy-dihydro-JA ([M-H]^- 227.1280, RT 4.29 min) (<b>D</b>), Indol-3-carboxylic acid ([M-H]^- 160.0390, RT 4.54 min) <b>(E</b>), JA ([M-H]^- 209.1178, RT 5.56 min) (<b>F</b>), 9,10-dihydro-JA ([M-H]^- 211.1334, RT 5.88 min) (<b>G</b>), Isoleucyl-C₁₁H₁₆O₂. ([M-H]^- 310.2028, RT 6.37 min) (<b>H</b>). Abbreviations: JA, jasmonic acid.</p

Substrate parameters defining of the Leudiking and Piret model in shake cultures of <i>L</i>. <i>theobromae</i> strain 2334 in volumes of 100, 250 and 500 mL.

<p>Substrate parameters defining of the Leudiking and Piret model in shake cultures of <i>L</i>. <i>theobromae</i> strain 2334 in volumes of 100, 250 and 500 mL.</p