scholarly journals Measuring the dihedral angle of water at a grain boundary in ice by an optical diffraction method

1991 ◽  
Vol 37 (125) ◽  
pp. 107-112 ◽  
Author(s):  
M.E.R. Walford ◽  
J.F. Nye
Keyword(s):  
Grain Boundary ◽  
Diffraction Pattern ◽  
Dihedral Angle ◽  
Boundary Energy ◽  
Monochromatic Light ◽  
Diffraction Method ◽  
Optical Diffraction ◽  
Optical Measurements ◽  
Polycrystalline Ice ◽  
Ice Water

AbstractOptical measurements have been made on the water lenses which form under pressure at grain boundaries in polycrystalline ice. Monochromatic light from a point source is focused by the lenses but, because the lenses are microscopic in size, the image is blurred by diffraction. The diffraction pattern observed under a microscope has been compared with the computed diffraction pattern to deduce the angle 2θat the rim of each lens. This is the dihedral angle for water at a grain boundary in ice, and gives the ratio of the grain-boundary energy to that of an ice-water interface. The most sensitive measurements are those made on the rings of the virtual diffraction pattern formed on the object side of the lens. They giveθ= 12.5 ± 0.5° for the grain boundary under observation, which is 26% lower than the previous value forθfound by ignoring diffraction.

scholarly journals Measuring the dihedral angle of water at a grain boundary in ice by an optical diffraction method

1991 ◽  
Vol 37 (125) ◽  
pp. 107-112 ◽  
Author(s):  
M.E.R. Walford ◽  
J.F. Nye
Keyword(s):  
Grain Boundary ◽  
Diffraction Pattern ◽  
Dihedral Angle ◽  
Boundary Energy ◽  
Monochromatic Light ◽  
Diffraction Method ◽  
Optical Diffraction ◽  
Optical Measurements ◽  
Polycrystalline Ice ◽  
Ice Water

Abstract Optical measurements have been made on the water lenses which form under pressure at grain boundaries in polycrystalline ice. Monochromatic light from a point source is focused by the lenses but, because the lenses are microscopic in size, the image is blurred by diffraction. The diffraction pattern observed under a microscope has been compared with the computed diffraction pattern to deduce the angle 2θ at the rim of each lens. This is the dihedral angle for water at a grain boundary in ice, and gives the ratio of the grain-boundary energy to that of an ice-water interface. The most sensitive measurements are those made on the rings of the virtual diffraction pattern formed on the object side of the lens. They give θ = 12.5 ± 0.5° for the grain boundary under observation, which is 26% lower than the previous value for θ found by ignoring diffraction.

scholarly journals Optical Measurements of Water Lenses in Ice

1987 ◽  
Vol 33 (114) ◽  
pp. 159-161 ◽  
Author(s):  
M.E.R. Walford ◽  
D.W. Roberts ◽  
I. Hill
Keyword(s):  
Grain Boundary ◽  
Specific Surface ◽  
Dihedral Angle ◽  
Focal Length ◽  
Water System ◽  
Optical Measurements ◽  
Free Energies ◽  
Minor Revision ◽  
Experimental Values ◽  
Ice Water

AbstractThe dihedral angle of water at a grain boundary in ice is found, by measuring the optical focal length of lenticular water inclusions, to be 33.6 ± 0.7°. The new result leads to only minor revision of published experimental values of specific surface free energies in the ice–water system (Ketcham and Hobbs, 1969).

scholarly journals Optical Measurements of Water Lenses in Ice

1987 ◽  
Vol 33 (114) ◽  
pp. 159-161 ◽  
Author(s):  
M.E.R. Walford ◽  
D.W. Roberts ◽  
I. Hill
Keyword(s):  
Grain Boundary ◽  
Specific Surface ◽  
Dihedral Angle ◽  
Focal Length ◽  
Water System ◽  
Optical Measurements ◽  
Free Energies ◽  
Minor Revision ◽  
Experimental Values ◽  
Ice Water

AbstractThe dihedral angle of water at a grain boundary in ice is found, by measuring the optical focal length of lenticular water inclusions, to be 33.6 ± 0.7°. The new result leads to only minor revision of published experimental values of specific surface free energies in the ice–water system (Ketcham and Hobbs, 1969).

scholarly journals The Geometry of Water Veins and Nodes in Polycrystalline Ice

1989 ◽  
Vol 35 (119) ◽  
pp. 17-22 ◽  
Author(s):  
J.F. Nye
Keyword(s):  
Surface Tension ◽  
Melting Point ◽  
Grain Boundary ◽  
Dihedral Angle ◽  
Average Length ◽  
Polycrystalline Ice ◽  
Vein Diameter

AbstractWater in polycrystalline ice at its melting point forms a system of veins at the three-grain junctions. The veins join together at nodes, which are the four-grain junctions. The shape of a node, a tetrahedron with non-spherical faces and open corners, is determined completely by the dihedral angle for water in contact with a grain boundary. Using the observed value for this angle, namely 33.6°, the paper computes the tetrahedral shape. This is a surface-tension problem with initially unknown boundaries. The result shows that the ratio of vein volume to node volume is R = 0.072 l/d, where l is the average length of a vein between two nodes, and d is the vein diameter measured between edges. For example, in a specimen of ice grown from the melt in the laboratory R was 18.

scholarly journals The Effect of Non-Hydrostatic Stress on Intergranular Water Veins and Lenses in Ice

1972 ◽  
Vol 11 (61) ◽  
pp. 81-101 ◽  
Author(s):  
J. F. Nye ◽  
S. Mae
Keyword(s):  
Melting Point ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Hydrostatic Stress ◽  
Pure Shear ◽  
Triple Junctions ◽  
Polycrystalline Ice ◽  
Glacier Ice ◽  
Set Up ◽  
Ice Water

AbstractPolycrystalline ice at the melting point has been observed in the laboratory to contain veins of water at the places where three grains meet. Under uniaxial compression lenticular water inclusions appeared at grain boundaries perpendicular to the stress, while the nearby vein began to freeze. A similar effect occurred in tension on grain boundaries parallel to the stress. When the stress on the plane of the boundary was a pure shear stress, no effect was observed. The water lenses produced by stress increased in size and decreased in number after the stress was removed. The effect under compression is explained quantitatively by the combined effects of curvature and pressure on the melting point of an ice–water interface. The rate of formation of the lenses and of their coarsening is greatly reduced by the internal pressures set up in the lenses as a result of expansion on freezing and contraction on melting; transient creep to accommodate volume changes is an essential part of the process. The effect in a grain boundary under tension may arise from pressure caused by sliding on other grain boundaries; it was absent in a bicrystal.It is concluded that internal melting and freezing at grain boundaries and veins will occur in temperate glacier ice, with some effect, not discussed here, on its permeability to water. Any pure solid at its melting point which has a dihedral angle for the liquid phase in contact with a grain boundary between 0° and 60° should show similar behaviour, in that non-hydrostatic stress should cause liquid to move away from triple junctions between grains and into grain boundaries. There may be implications for the Frank theory of the upwelling of melt fluid in the Earth’s upper mantle.

scholarly journals STUDIES ON OSMOTIC EQUILIBRIUM AND ON THE KINETICS OF OSMOSIS IN LIVING CELLS BY A DIFFRACTION METHOD

1935 ◽  
Vol 19 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Balduin Lucké ◽  
Martin G. Larrabee ◽  
H. Keffer Hartline
Keyword(s):  
Cell Surface ◽  
Osmotic Pressure ◽  
Diffraction Pattern ◽  
Monochromatic Light ◽  
Diffraction Method ◽  
Living Cells ◽  
Individual Variability ◽  
Concentration Difference ◽  
Osmotic Equilibrium ◽  
Kinetics Of

1. Osmotic equilibrium and kinetics of osmosis of living cells (unfertilized eggs of Arbacia punctulata) have been studied by a diffraction method. This method consists of illuminating a suspension of cells by parallel monochromatic light and measuring, by means of telescope and scale, the angular dimensions of the resulting diffraction pattern from which the average volume of the cells may be computed. The method is far less laborious and possesses several advantages over direct measurement of individual cells. The average size of a large number of cells is obtained from a single measurement of the diffraction pattern and thus individual variability is averaged out. The observations can be made at intervals of a few seconds, permitting changes in volume to be followed satisfactorily. During the measurements the cells are in suspension and are constantly stirred. 2. Volumes of cells in equilibrium with solutions of different osmotic pressure have been determined. In agreement with our previous experiments, based upon direct microscope measurements, we have confirmed the applicability of the law of Boyle-van't Hoff to these cells; that is to say, the product of volume and pressure has been found to be approximately constant if allowance be made for the volume of osmotically inactive material of the cell contents. The volume of osmotically inactive material was found to be, on the average, 12 per cent of the initial cell volume; in eggs from different animals this value ranged from 6 to 20 per cent. 3. Permeability to water of the Arbacia egg has been found to average, at 22°C., 0.106 cubic micra of water per square micron of cell surface, per minute, per atmosphere of difference in osmotic pressure. 4. Permeability to ethylene glycol has been found to average, at 24°C., 4.0 x 10–15 mols, per square micron of cell surface, per minute, for a concentration difference of 1 mol per liter. This is in agreement with the values reported by Stewart and Jacobs.

scholarly journals The Effect of Non-Hydrostatic Stress on Intergranular Water Veins and Lenses in Ice

1972 ◽  
Vol 11 (61) ◽  
pp. 81-101 ◽  
Author(s):  
J. F. Nye ◽  
S. Mae
Keyword(s):  
Melting Point ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Hydrostatic Stress ◽  
Pure Shear ◽  
Triple Junctions ◽  
Polycrystalline Ice ◽  
Glacier Ice ◽  
Set Up ◽  
Ice Water

AbstractPolycrystalline ice at the melting point has been observed in the laboratory to contain veins of water at the places where three grains meet. Under uniaxial compression lenticular water inclusions appeared at grain boundaries perpendicular to the stress, while the nearby vein began to freeze. A similar effect occurred in tension on grain boundaries parallel to the stress. When the stress on the plane of the boundary was a pure shear stress, no effect was observed. The water lenses produced by stress increased in size and decreased in number after the stress was removed. The effect under compression is explained quantitatively by the combined effects of curvature and pressure on the melting point of an ice–water interface. The rate of formation of the lenses and of their coarsening is greatly reduced by the internal pressures set up in the lenses as a result of expansion on freezing and contraction on melting; transient creep to accommodate volume changes is an essential part of the process. The effect in a grain boundary under tension may arise from pressure caused by sliding on other grain boundaries; it was absent in a bicrystal.It is concluded that internal melting and freezing at grain boundaries and veins will occur in temperate glacier ice, with some effect, not discussed here, on its permeability to water. Any pure solid at its melting point which has a dihedral angle for the liquid phase in contact with a grain boundary between 0° and 60° should show similar behaviour, in that non-hydrostatic stress should cause liquid to move away from triple junctions between grains and into grain boundaries. There may be implications for the Frank theory of the upwelling of melt fluid in the Earth’s upper mantle.

scholarly journals Structure and Behaviour of Grain Boundaries in Polycrystalline Ice

1978 ◽  
Vol 21 (85) ◽  
pp. 589-605
Author(s):  
Akira Higashi
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Moving Boundary ◽  
Boundary Energy ◽  
Coincidence Site Lattice ◽  
Geometrical Model ◽  
Grain Boundary Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Polycrystalline Ice

AbstractRecent progress in studies of the structure and behaviour of grain boundaries in ice are reviewed. As a lattice geometrical model of the boundary, the coincidence-site lattice (CSL) model is considered for ice crystals. Some evidence of the validity of this model is presented through observations of special shapes of natural snow, results of grain-boundary energy measurements, and direct microscopic observations of boundaries by X-ray diffraction topography. Although methods of measurement of grain-boundary energy have been developed recently, results are still not adequate to be analysed in terms of real energetics for comparison with models of atomic bonding. Modern methods of observing grain boundaries in ice using X-ray diffraction topography are described. Observations of migrating boundaries have revealed that faceting along most closely packed CSL points impede the migration of the CSL boundaries whilst increased numbers of steps among facets with boundaries of other kinds enhance it. The mobility of a fast-moving boundary has been determined to be of the order of 10-10 cm3 dyn-1 s-1 (10-11 m3 N-1 s-1) either in the case when the driving force is the capillary force due to the boundary energy or when it is the stored energy of dislocations.

scholarly journals Structure and Behaviour of Grain Boundaries in Polycrystalline Ice

1978 ◽  
Vol 21 (85) ◽  
pp. 589-605 ◽  
Author(s):  
Akira Higashi
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Moving Boundary ◽  
Boundary Energy ◽  
Coincidence Site Lattice ◽  
Geometrical Model ◽  
Grain Boundary Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Polycrystalline Ice

Abstract Recent progress in studies of the structure and behaviour of grain boundaries in ice are reviewed. As a lattice geometrical model of the boundary, the coincidence-site lattice (CSL) model is considered for ice crystals. Some evidence of the validity of this model is presented through observations of special shapes of natural snow, results of grain-boundary energy measurements, and direct microscopic observations of boundaries by X-ray diffraction topography. Although methods of measurement of grain-boundary energy have been developed recently, results are still not adequate to be analysed in terms of real energetics for comparison with models of atomic bonding. Modern methods of observing grain boundaries in ice using X-ray diffraction topography are described. Observations of migrating boundaries have revealed that faceting along most closely packed CSL points impede the migration of the CSL boundaries whilst increased numbers of steps among facets with boundaries of other kinds enhance it. The mobility of a fast-moving boundary has been determined to be of the order of 10-10 cm3 dyn-1 s-1 (10-11 m3 N-1 s-1) either in the case when the driving force is the capillary force due to the boundary energy or when it is the stored energy of dislocations.

Light Optical Diffraction Studies of Macromolecular Ultrastructure

1970 ◽  
Vol 28 ◽  
pp. 258-259
Author(s):  
Glen B. Haydon
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Electron Micrograph ◽  
Its Analysis ◽  
Resolution Electron ◽  
Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

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