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An investigation of iron in layer structured silicate mineralsCharman, R. G. January 1988 (has links)
No description available.
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Related microstructural development on firing kaolinite, illite and smectite claysMcConville, Caspar J. January 1999 (has links)
No description available.
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The anisotropic elastic properties of clay-rich rocksAndrea, Martijn January 1996 (has links)
No description available.
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A novel approach to the synthesis of layered structuresTsieane, Sebabatso January 2016 (has links)
School of Chemistry, Faculty of Science, University of Witwatersrand, Johannesburg, South
Africa
Johannesburg, 2016 / The synthesis of pure layered clay minerals has to be evaluated at low temperatures,
pressures and short reaction times to scale up to commercial processes. However, it has been
discovered that under such reaction conditions, reactions experience considerable difficulties.
Such difficulties include low yields of products that occur with associated other minerals, and
long reaction times. Thus, the synthesis of synthetic clay minerals is commonly approached
by the hydrothermal technique, which involves the crystallization of substances at high
vapour pressures and temperatures. However, the employment of the hydrothermal technique
is time- and water consuming, thus, the need for an energy-saving and reaction accelerating
process method. In the work presented here particular interest is paid to the synthetic layered
clay mineral pyrophyllite, which is used as a pressure transmitting medium in the making of
synthetic diamond. As opposed to the hydrothermal technique, this work adopts the synthetic
method resin gel for the synthesis of these layered materials. Preliminary results by Loren
Purcell have shown that the resin-gel synthesis method has been able to make apparently
layered materials that appear to have a thermal gravimetric profile that indicates a gradual
mass loss of both surface and structural water. The work presented here reproduces these
results and further explores other Si\Al ratio’s, silica and alumina precursors for the synthesis
of pyrophyllite-like materials and the different heating methods of the gels. Transmission
electron microscopy (TEM) shows that irrespective of the synthesis conditions sheet-like or
platy crystals are formed. Scanning electron microscopy (SEM) confirms on the TEM
observations and shows that the surface texture of the crystals has a compact appearance.
Thermal gravimetric analysis (TGA) of the materials confirms on previous observations from
preliminary results, materials indicate both adsorbed surface and interlayer water. Powder Xray
diffraction (PXRD) is inconclusive of the determination of phase pure pyrophyllite.
Furthermore, Brunauer-Emmett-Teller (BET) reveals that the materials are mesoporous solids
and the materials were also characterised by DSC, Raman and HRTEM. / MT2016
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The accumulation of aluminium and it's effect on the uptake and distribution of Ca, Mg, K, Mn, Fe, Cu and Zn in Camellia sinesis (L.)Carr, Hilda P 01 January 2001 (has links)
No description available.
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The effects of processing on sodium-potassium and calcium-phosphorus ratios in foodsRonan, Kathleen M. 04 June 1981 (has links)
The objective of this study was to determine the effects of processing
on sodium - potassium and calcium - phosphorus ratios in tuna canned in
oil and in water, peanut butter, white and whole wheat flours. Mineral
levels were determined by atomic absorption spectrophotometry in food
samples at various stages in the production of these finished products.
The average sodium - potassium ratios of the tuna samples were: 1.37
raw, 1.24 precooked, 1.87 canned in oil and 1.61 canned in water.
Processing did not significantly effect sodium and potassium ratios in
canned tuna. The average calcium - phosphorus ratios of the tuna samples
were: 0.034 raw, 0.024 precooked, 0.034 canned in oil and 0.065 canned
in water. The ratio of the canned in water meat was significantly
effected by processing.
The average sodium - potassium ratios of the peanut samples were:
0.034 raw, 0.043 roasted, 0.031 blanched and 0.781 peanut butter. The
ratio of peanut butter was significantly greater than the ratios of
the other peanut samples. The average calcium - phosphorus ratios of
the peanut samples were: 0.148 raw, 0.121 roasted, 0.141 blanched and
0.128 peanut butter. These ratios were not significantly effected by
processing.
The average sodium - potassium ratio was 0.16 in white flours,
0.84 in whole wheat flour and 0.89 in the kernel. The average calcium -
phosphorus ratio was 0.14 in white flours, 0.07 in whole wheat flour
and 0.07 in the kernel. The ratios of the kernel and whole wheat
flour were not significantly different. Processing significantly effected
the ratios of the white flour.
The preferred concentration of sodium chloride and a 1:1 sodium -
potassium chloride mixture in white and whole wheat breads was also
studied. Bread samples were made with 1.0%, 0.75% and 0.5% levels of
both salt treatments. They were evaluated by an untrained flavor panel
for overall desirability with a nine point hedonic scale. The judges
preferred a sodium chloride white bread with a 7.0 sodium - potassium
ratio, and a sodium chloride whole wheat bread with a 3.29 ratio. These
ratios were both lower than those found in commercial products. White
and whole wheat breads made with 0.75% sodium chloride were as acceptable
as breads made with 1.0% 1:1 sodium - potassium chloride mixture.
The sodium - potassium ratio of the salt mixture white bread was 1.20 and
the ratio of the whole wheat bread was 0.91.
The addition of salt to finished products for flavor had an effect
on the sodium - potassium ratio of the foods studied. Also, reducing
the amount of added salt to commercial breads and replacing some sodium
chloride with potassium chloride were acceptable means of lowering
the sodium - potassium ratios of white and whole wheat breads. / Graduation date: 1982
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Degradação da pedra em edifícios históricos-o caso da Sé de LisboaDionísio, Maria Amélia Alves Rangel January 2002 (has links)
No description available.
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108 |
Nutrient-driven colonization and weathering of silicates /Rogers, Jennifer Roberts, January 2000 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 219-237). Available also in a digital version from Dissertation Abstracts.
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The concentration of rutileHess, James Gordon, 1928- January 1954 (has links)
No description available.
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Lettuce nutrition as influenced by nitrogen, phosphorus, potassium, and magnesium fertilizationStanersen, Lewis Albert, 1931- January 1963 (has links)
No description available.
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