SCANNING ELECTRON MICROSCOPE (SEM) OBSERVATIONS OF SOIL STRUCTURE CHANGES INDUCED BY SODIUM-CALCIUM EXCHANGE IN RELATION TO HYDRAULIC CONDUCTIVITY

Numerous studies have been completed in recent years on the alteration of the hydraulic conductivity of clayey soils as a result of exposure to concentrated organic or inorganic permeants. These hydraulic conductivity changes have been attributed to either changes in microstructure, due to contraction of the diffuse double layer, or to the alteration of the macrostructure, as a result of volume changes leading to shrinkage fractures or fissures. In this paper, the change in hydraulic conductivity of a highly plastic natural clay during exposure to a concentrated sodium chloride (NaCl) solution is described. The performance of samples with three different initial soil structures, prepared by slurry, static compaction, and kneading compaction, were investigated under various levels of confining stress. Hydraulic conductivity tests were carried out before and after the samples were exposed to the NaCl solutions. Scanning electron microscope photography was used to compare the soil structures before and after brine permeation. The test results show that the alteration of hydraulic conductivity is strongly related to the initial soil structure and the level of confining stress. No significant change in the microfabric of the clay was observed; however, the size of the interaggregate pores appeared to increase as a result of the physicochemical volume change that occurred during brine permeation. The increase in hydraulic conductivity that occurred during brine permeation could be prevented by increasing the level of confining stress. The stress levels at which significant increases in hydraulic conductivity occurred appeared to be coincident with low levels of vertical stress which allowed the sample to undergo lateral shrinkage and a subsequent loss of confinement. Key words : hydraulic conductivity, clay soils, osmotic consolidation, sodium chloride brine, soil structure, scanning electron microscope.

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The microscopic examination of the structure of sub-surface horizons of soils

Outlook on Agriculture ◽

10.1177/003072707600800607 ◽

1976 ◽

Vol 8 (6) ◽

pp. 348-354 ◽

Cited By ~ 22

Author(s):

P Bullock ◽

C P Murphy

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Microscopic Examination ◽

Soil Structure ◽

Thin Sections ◽

X Ray ◽

Cultural Conditions ◽

Structural Types ◽

Scanning Electron

What is meant by “soil structure”? Microscopic examination of thin sections of soil, using such instruments as the polarising microscope, X-ray diffractometer and scanning electron microscope has enabled a classification of the components of soils and their structural types to be built up. Now with the aid of the image-analysing computer these components can be quantified rapidly, characteristics may be calculated and their behaviour under varying cultural conditions predicted.

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PROPERTIES OF TWO FRAGIPAN SOILS IN NOVA SCOTIA INCLUDING SCANNING ELECTRON MICROGRAPHS

Canadian Journal of Soil Science ◽

10.4141/cjss74-022 ◽

1974 ◽

Vol 54 (2) ◽

pp. 159-170 ◽

Cited By ~ 16

Author(s):

CHANG WANG ◽

J. L. NOWLAND ◽

H. KODAMA

Keyword(s):

Electron Microscope ◽

Nova Scotia ◽

Hydraulic Conductivity ◽

Scanning Electron Microscope ◽

Clay Fraction ◽

Fine Sand ◽

Scanning Electron Micrographs ◽

Moderate Amount ◽

High Bulk ◽

Scanning Electron

About 250,000 acres of soil with fragipan have been mapped in Nova Scotia. The fragipan horizons of two soils (Tormentine and Debert) reported in this paper are typical for the province. They have high bulk densities and low saturated hydraulic conductivity. They are also low in organic carbon and free oxides. They are high in fine sand and silt but low in clay, and the fragments of fragipan are readily slaked in water. Mica, chlorite, vermiculite, and kaolinite were found in the clay fractions of both soils throughout the two profiles. A moderate amount of smectite was found in the clay fractions of the Ae horizon of Debert but not in the Tormentine profile. A significant amount of clay increase in both fine and total clay fraction was found in the Bf horizon of the Tormentine soil and the Bmgj and Btx horizons of the Debert soil, and results from translocation or lessivage. The brittleness and other associated properties of the fragipans were attributed to clay bridges linking coarser particles, which were shown in the scanning electron microscope pictures.

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The Alteration of the Pore Spaces in Sandstones

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071491 ◽

1973 ◽

Vol 31 ◽

pp. 210-211

Author(s):

R. E. Ferrell ◽

G. G. Paulson

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

The Other ◽

Coarse Grained ◽

Depositional Fabric ◽

Soluble Components ◽

Scanning Electron ◽

Shape And Size

The pore spaces in sandstones are the result of the original depositional fabric and the degree of post-depositional alteration that the rock has experienced. The largest pore volumes are present in coarse-grained, well-sorted materials with high sphericity. The chief mechanisms which alter the shape and size of the pores are precipitation of cementing agents and the dissolution of soluble components. Each process may operate alone or in combination with the other, or there may be several generations of cementation and solution.The scanning electron microscope has ‘been used in this study to reveal the morphology of the pore spaces in a variety of moderate porosity, orthoquartzites.

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The Broad Applications of the Scanning Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100062002 ◽

1969 ◽

Vol 27 ◽

pp. 20-21

Author(s):

C. T. Nightingale ◽

S. E. Summers ◽

T. P. Turnbull

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Light Microscopy ◽

Surface Topography ◽

Great Depth ◽

Resolving Power ◽

Depth Of Field ◽

Pictorial Representations ◽

Scanning Electron

The ease of operation of the scanning electron microscope has insured its wide application in medicine and industry. The micrographs are pictorial representations of surface topography obtained directly from the specimen. The need to replicate is eliminated. The great depth of field and the high resolving power provide far more information than light microscopy.

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Observability of Very Thick Specimen by Using Transmission Scanning Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064189 ◽

1971 ◽

Vol 29 ◽

pp. 26-27

Author(s):

K. Shibatomi ◽

T. Yamanoto ◽

H. Koike

Keyword(s):

Electron Microscope ◽

Image Quality ◽

Scanning Electron Microscope ◽

Chromatic Aberration ◽

Image Contrast ◽

Objective Lens ◽

Thick Specimen ◽

Transmission Electron ◽

Scanning Electron

In the observation of a thick specimen by means of a transmission electron microscope, the intensity of electrons passing through the objective lens aperture is greatly reduced. So that the image is almost invisible. In addition to this fact, it have been reported that a chromatic aberration causes the deterioration of the image contrast rather than that of the resolution. The scanning electron microscope is, however, capable of electrically amplifying the signal of the decreasing intensity, and also free from a chromatic aberration so that the deterioration of the image contrast due to the aberration can be prevented. The electrical improvement of the image quality can be carried out by using the fascionating features of the SEM, that is, the amplification of a weak in-put signal forming the image and the descriminating action of the heigh level signal of the background. This paper reports some of the experimental results about the thickness dependence of the observability and quality of the image in the case of the transmission SEM.

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Resolution of a Transmitted Electron Image Formed by A Scanning Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100068928 ◽

1970 ◽

Vol 28 ◽

pp. 386-387

Author(s):

S. Takashima ◽

H. Hashimoto ◽

S. Kimoto

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Chromatic Aberration ◽

Objective Lens ◽

Specimen Thickness ◽

Probe Diameter ◽

Transmission Electron ◽

Electron Image ◽

Conventional Transmission Electron Microscope ◽

Scanning Electron

The resolution of a conventional transmission electron microscope (TEM) deteriorates as the specimen thickness increases, because chromatic aberration of the objective lens is caused by the energy loss of electrons). In the case of a scanning electron microscope (SEM), chromatic aberration does not exist as the restrictive factor for the resolution of the transmitted electron image, for the SEM has no imageforming lens. It is not sure, however, that the equal resolution to the probe diameter can be obtained in the case of a thick specimen. To study the relation between the specimen thickness and the resolution of the trans-mitted electron image obtained by the SEM, the following experiment was carried out.

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Characterization of Sputtered Films using the Scanning Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100070667 ◽

1973 ◽

Vol 31 ◽

pp. 44-45

Author(s):

R. F. Schneidmiller ◽

W. F. Thrower ◽

C. Ang

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Thin Film Deposition ◽

Film Deposition ◽

Sputtered Films ◽

Plasma Sputtering ◽

Microelectronic Devices ◽

Control Film ◽

Scanning Electron

Solid state materials in the form of thin films have found increasing structural and electronic applications. Among the multitude of thin film deposition techniques, the radio frequency induced plasma sputtering has gained considerable utilization in recent years through advances in equipment design and process improvement, as well as the discovery of the versatility of the process to control film properties. In our laboratory we have used the scanning electron microscope extensively in the direct and indirect characterization of sputtered films for correlation with their physical and electrical properties.Scanning electron microscopy is a powerful tool for the examination of surfaces of solids and for the failure analysis of structural components and microelectronic devices.

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Field Emission SEM Equipped With Noise Compensator

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071958 ◽

1973 ◽

Vol 31 ◽

pp. 302-303

Author(s):

S. Saito ◽

H. Todokoro ◽

S. Nomura ◽

T. Komoda

Keyword(s):

Electron Microscope ◽

High Resolution ◽

Scanning Electron Microscope ◽

Field Emission ◽

Low Contrast ◽

Probe Current ◽

High Resolution Images ◽

Scanning Electron

Field emission scanning electron microscope (FESEM) features extremely high resolution images, and offers many valuable information. But, for a specimen which gives low contrast images, lateral stripes appear in images. These stripes are resulted from signal fluctuations caused by probe current noises. In order to obtain good images without stripes, the fluctuations should be less than 1%, especially for low contrast images. For this purpose, the authors realized a noise compensator, and applied this to the FESEM.Fig. 1 shows an outline of FESEM equipped with a noise compensator. Two apertures are provided gust under the field emission gun.

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Visualization of Internal Skin Structures with the Scanning Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100062130 ◽

1969 ◽

Vol 27 ◽

pp. 46-47

Author(s):

Emil Bernstein

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Great Depth ◽

Hair Follicles ◽

Depth Of Field ◽

Pig Skin ◽

Realistic Picture ◽

Main Components ◽

Scanning Electron

An interesting method for examining structures in g. pig skin has been developed. By modifying an existing technique for splitting skin into its two main components—epidermis and dermis—we can in effect create new surfaces which can be examined with the scanning electron microscope (SEM). Although this method is not offered as a complete substitute for sectioning, it provides the investigator with a means for examining certain structures such as hair follicles and glands intact. The great depth of field of the SEM complements the technique so that a very “realistic” picture of the organ is obtained.

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