Anisotropy of the rock drill core elastic properties at uniaxial loading

A system has been developed for the continuous and stepwise scanning of rock drill cores for gamma‐ray spectrometric determinations of uranium, thorium, and potassium. The apparatus accomodates 3‐ to 4‐cm‐diameter core as it passes two opposing 2‐inch diameter by 3‐inch‐ thick NaI(Tl) detectors, either continuously, at speeds ranging from one to several meters per hour, or in steps of 5 cm or more. Resulting gamma‐ray spectra, as recorded with a multi channel analyzer, are computer processed, furnishing scale diagrams of individual radioelement contents and Th/U ratios in the core. Whole‐rock assays of one‐meter‐long core sections by continuous scanning are accurate and precise to within 10 percent or better. In the step‐scanning mode, the system can resolve peak concentrations of U and Th with an accuracy of about 15 percent. Continuous one‐meter scans of 3500 m of core from the Ilímaussaq intrusion, South Greenland, provided an evaluation of uranium resources in the course of seven months. Examination of the continuous‐scan diagrams indicated areas of geochemical interest, such as sharp and transitional contacts and mineralized zones. These were investigated more closely by step scanning, disclosing detailed variations of U and Th. Contents of U and Th determined by scanning of drill core were consistent with the gross gamma‐ray counting rates measured in the boreholes.

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Influence of out-of-plane ply waviness on elastic properties of composite laminates under uniaxial loading

Composite Structures ◽

10.1016/j.compstruct.2015.05.062 ◽

2015 ◽

Vol 132 ◽

pp. 440-450 ◽

Cited By ~ 13

Author(s):

Jun Zhu ◽

Jihui Wang ◽

Lei Zu

Keyword(s):

Elastic Properties ◽

Composite Laminates ◽

Uniaxial Loading ◽

Out Of Plane

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Electron Microscopy and image reconstruction reveal the structural basis for spectrin's elastic properties

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122952 ◽

1992 ◽

Vol 50 (1) ◽

pp. 510-511

Author(s):

Amy M. McGough ◽

Robert Josephs

Keyword(s):

Electron Microscopy ◽

Elastic Properties ◽

Conformational Changes ◽

Quaternary Structure ◽

Three Dimensional ◽

Membrane Skeleton ◽

Projection Algorithm ◽

Structural Basis ◽

Iterative Approximation ◽

Membrane Skeletons

The remarkable deformability of the erythrocyte derives in large part from the elastic properties of spectrin, the major component of the membrane skeleton. It is generally accepted that spectrin's elasticity arises from marked conformational changes which include variations in its overall length (1). In this work the structure of spectrin in partially expanded membrane skeletons was studied by electron microscopy to determine the molecular basis for spectrin's elastic properties. Spectrin molecules were analysed with respect to three features: length, conformation, and quaternary structure. The results of these studies lead to a model of how spectrin mediates the elastic deformation of the erythrocyte.Membrane skeletons were isolated from erythrocyte membrane ghosts, negatively stained, and examined by transmission electron microscopy (2). Particle lengths and end-to-end distances were measured from enlarged prints using the computer program MACMEASURE. Spectrin conformation (straightness) was assessed by calculating the particles’ correlation length by iterative approximation (3). Digitised spectrin images were correlation averaged or Fourier filtered to improve their signal-to-noise ratios. Three-dimensional reconstructions were performed using a suite of programs which were based on the filtered back-projection algorithm and executed on a cluster of Microvax 3200 workstations (4).

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The buckling of thin EM specimens

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177386 ◽

1990 ◽

Vol 48 (4) ◽

pp. 850-851

Author(s):

A.R. Thölén

Keyword(s):

Electron Microscope ◽

Elastic Properties ◽

Crystal Surface ◽

Specimen Surface ◽

Radius Of Curvature ◽

Thin Foils ◽

Thin Electron ◽

Regular Patterns

Thin electron microscope specimens often contain irregular bend contours (Figs. 1-3). Very regular bend patterns have, however, been observed around holes in some ion-milled specimens. The purpose of this investigation is twofold. Firstly, to find the geometry of bent specimens and the elastic properties of extremely thin foils and secondly, to obtain more information about the background to the observed regular patterns.The specimen surface is described by z = f(x,y,p), where p is a parameter, eg. the radius of curvature of a sphere. The beam is entering along the z—direction, which coincides with the foil normal, FN, of the undisturbed crystal surface (z = 0). We have here used FN = [001]. Furthermore some low indexed reflections are chosen around the pole FN and in our fcc crystal the following g-vectors are selected:

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