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Morphological determination of pore connectivity as a function of pore size using serial sections (1997)

VOGEL, H. J.

Oxford, UK : Blackwell Publishing Ltd

European journal of soil science 48 (1997), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: The geometry of pore space in soil is considered to be the key in understanding transport of water, gas and solute. However, a quantitative and explicit characterization, by means of a physical interpretation, is difficult because of the geometric complexity of soil structure.Pores larger than 40 μm within two soil horizons have been analysed morphologically on 3-dimensional digital representations of the pore space obtained by serial sections through impregnated specimens. The Euler-Poincaré characteristic has been determined as an index of connectivity in three dimensions. The pore connectivity is quantified as a function of the minimum pore diameter considered leading to a connectivity function of the pore space. Different pore size classes were distinguished using 3-dimensional erosion and dilation. The connectivity function turned out to differentiate between two soil materials. The pore space in an upper Ah horizon is intensely connected through pores between 40 and 100 μm, in contrast to the pore space in the AhBv beneath it. The morphological pore-size distributions were compared to the pore-size distribution obtained by water retention measurements. The discrepancy between these different methods corresponds to the expectation due to pore connectivity.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-2389.1997.tb00203.x

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The dependence of friction anisotropies on themolecular organisation of LB films as observed by AFM (1997)

Gourdon, D. ; Burnham, N.A. ; Kulik, A. ; [et al.]

Springer

Tribology letters 3 (1997), S. 317-324

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ISSN: 1573-2711

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract We performed lateral force microscopy on thiolipid Langmuir-Blodgett (LB) films physisorbed on mica substrates with asilicon tip of an atomic force microscope. The structure ofcondensed domains, reflecting their symmetric morphology, wasobserved. The lateral (friction) forces were measured as a function of (normal) applied load, of sliding velocity and of themolecular orientation of these films. We found that at a fixedvelocity, lateral force increases with applied load in a linearfashion. Within the velocity range 0.01 to~50μm/s, the lateral force signal initiallyincreases monotonically with velocity (static regime) and thenstabilises when the tip begins sliding. The friction force andthe observed asymmetry in the quasi-static ``friction-loops''(torsion of the tip during a forward/reverse scan) were foundto be dependent on the domain orientation with respect to the scan direction, while the measured adhesive force remainedconstant. Together, friction and asymmetry reveal and mapmolecular packing and tilt.