Calvin M. Stewart

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Human erythrocytes and erythrocyte ghost membranes were treated with native and modified melittins, up to 250 nmol/mg membrane protein. Native melittin induced aggregation of intramembranous particles (IMPs, observed by freeze-fracture electron microscopy), and created large, smooth bilayer areas devoid of IMP. The degree of IMP aggregation increased with(More)
The molar ratio of cholesterol to phospholipid (C/P) in human erythrocyte membrane is modified by incubating the cells with liposomes of various C/P ratios. The observed increase in cell surface area may be accounted for by the addition of cholesterol molecules. Fusion between liposomes and cells or attachment of liposomes to cells is not a significant(More)
Bark was stripped, at monthly intervals, from the stems of ten previously-unsampled trees of Eucalyptus regnans F. Muell. The exposed surfaces of inner phloem and outer xylem yielded phloem and cambial saps which were rapidly frozen. After freeze drying to determine the contents of water and dry-matter, the samples were extracted with 80% ethanol. The main(More)
To capture the mechanical response of Ni-based materials, creep deformation and rupture experiments are typically performed. Long term tests, mimicking service conditions at 10,000 h or more, are generally avoided due to expense. Phenomenological models 26–31) model can accurately estimate tertiary creep damage over extended histories. Creep deformation and(More)
Directionally-solidified (DS) Ni-base superalloys are commonly applied as turbine materials to primarily withstand creep conditions manifested in either marine-, air-or land-based gas turbines components. The thrust for increased efficiency of these systems, however, translates into the need for these materials to exhibit considerable strength and(More)
Keywords: Transversely-isotropic Continuum damage mechanics (CDM) Directionally-solidified Ni-base superalloy Void induced anisotropy Multiaxial a b s t r a c t When an anisotropic material is subject to creep conditions and a complex state of stress, an anisotropic creep damage behavior is observed. Previous research has focused on the anisotropic creep(More)
Creep deformation and rupture experiments are conducted on samples of the Ni-base superalloy directionally solidified GTD-111 tested at temperatures between 649° C and 982° C and two orientations (longitudinally and transversely oriented). The secondary creep constants are analytically determined from creep deformation experiments. The classical(More)
Directionally solidified (DS) Ni-base superalloys have become a commonly used material in gas turbine components. Controlled solidification during the material manufacturing process leads to a special alignment of the grain boundaries within the material. This alignment results in different material properties dependent on the orientation of the material.(More)
Anisotropic creep-damage modeling has become an increasingly important prediction technique in both the aerospace and industrial gas turbine industries. The introduction of tensorial damage mechanics formulations in modeling tertiary creep behavior has lead to improved predictions of the creep strain that develops due to anisotropic grain structures and the(More)
The classic Kachanov-Rabotnov isotropic creep damage constitutive model has been used in many situations to predict the creep deformation of high temperature components. Typically, the secondary creep behavior is determined by analytical methods; however, the tertiary creep damage constants are found using a mixture of trial and error and numerical(More)