bluuebunny/crossref_metadata_2025 huggingface dataset:
Petrology of the Dry Branch, Georgia, Kaolin Deposits
Authors: Jonas Edward C.
Published: August 2006

Samples from kaolin deposits in the Dry Branch, Georgia, area were examined in’ oriented thin section, by X-ray diffraction, and as carefully disaggregated sand-sized grains. The object was to determine the orientation of kaolinite crystals with respect to any gross stratification in the deposits and with respect to their mineral precursors.

Large muscovite grains show a preferred horizontal orientation which produces a noticeable stratification in some soft kaolins in which they are relatively abundant. Interleaved kaolinite is oriented with its cleavage parallel to that of the remaining unaltered muscovite and is of the b-axis disordered variety. Pseudomorphs of kaolinite after feldspar occur in both the soft kaolins and the associated sandstones. These show no preferred orientation and are well-crystallized kaolinite. Authigenic kaolinite growing as vermicular “books” in the kaolin deposits and sandstones shows no preferred orientation direction and is well-crystallized also.

These observations lead to the conclusion that these Georgia kaolin deposits were not sedimented in still-standing waters as the mineral kaolinite. Major mineral constituents of the original sediment were muscovite and feldspar. Post-depositional alteration of these minerals has occurred as well as recrystallization of some of the kaolinite.
The Characteristics of Filter Pressed Kaolinite-Water Pastes
Authors: West Richard
Published: August 2006

A Georgia kaolin was selected for investigation because of its large, euhedral, platelike particles and mineral composition consisting of 96 per cent kaolinite. The clay was prepared as a suspension and treated with various water-soluble compounds, with or without the addition of an organic colloid, to determine the role of the organic material in the flocculation and deflocculation characteristics of the clay as measured by the rate of filtration under pressure. Although the organic colloid acted as a strong deffocculant alone, 1 per cent of it actually increased the flocculation action of aluminum sulfate and yet increased the deflocculation action of sodium sulfate.

Water-soluble compounds were added to the clay-water slip and then either a cation exchange resin or an anion exchange resin was added to replace either the cation with H+lor the anion with OH-1. The filtration characteristics of these prepared slips indicated that the anions studied —CI-1, SO4-a, and PO4-3— play a passive role in the flocculation or the deflocculation of the clay-water slips but that these ions often have a profound effect in combination with the cations. The cations play the active role in flocculation and deflocculation. Al+aacted as a strong flocculant and Na+1acted as a strong deflocculant. Small additions of Ca+aacted as a flocculant by increasing the rate of filtration of the clay-water slip but further additions decreased the rate of filtration.

The ratio of the amount of clay to water in the slip shows an important relationship with rate of filtration. A slip with 25 per cent clay had a relatively low rate of filtration and yielded a filter cake with a higher bulk density in the wet and the dry state than did a slip with 40 per cent clay. The lower viscosity of the slip with 25 per cent clay may allow a greater freedom for particle orientation as deposited on the filter cake than a slip with 40 per cent clay having a higher viscosity.

Electron micrographs of the top and edge of filter cakes prepared from flocculated and deflocculated clay show that the structure of both is similar with regard to parallelism of plates. However, the deflocculated clay deposits in a close-packed parallel arrangement whereas the flocculated clay deposits with some slight displacement of the plates but in a parallel arrangement.
Stabilities of Three-Layer Phyllosilicates Related to Their Ionic-Covalent Bonding
Authors: Tlapek John W. , Keller W. D.
Published: August 2006

The anhydrous structures of three-layer phyllosilicates are destroyed by heating, as in differential thermal analyses, over a range of temperatures starting from about 775°C, mean temperature for pyrophyllite, and rising to about 1075°C, a mean temperature for biotite. Parallel to the trend of increasing temperature of stability (and destruction) is an increased ratio of substituted Al for Si in the tetrahedral layers and, in some occurrences, of Mg for Al in the octahedral layers. These substitutions increase the degree of ionic bonding (and decrease the covalent bonding) within the oxygen framework. The electronegativity difference between the cation and oxygen increases as Al substitutes for Si, and Mg for Al. Increase in ionic character of a compound is compatible, from chemical considerations, with increase in thermal stability and susceptibility of the compound to alteration by water.

The principle illustrated by the phyllosilicates applies likewise to mineral groups of other silicate structure, such as the anorthite-albite series, the forsterite—fayalite series, and others.
Surface Properties of Alumino-Silicates
Authors: Fripiat J. J.
Published: August 2006

As an approach to reviewing the surface properties of alumino-silicates, this paper considers the relationships between constitution hydroxyls, surface hydroxyls, chemisorbed and physically adsorbed water molecules and exchangeable cations. One of the main characteristics of clay minerals is, indeed, the development of hydrated high surface area, electrically charged. For this purpose the surface topography, the origin of the electrical charge, and the properties of water molecules held by Van der Waals, or stronger forces are successively studied. Chemisorbed water molecules appear to have a higher than usual degree of dissociation; this phenomenon exerts a deep influence on surface properties such as surface electrical conductivity, chemisorption of ammonia and amines, and their transformation.

When surfaces are thoroughly dehydrated, constitution protons are probably delocalized in the oxygen framework and this delocalization process probably precedes dehydroxylation.

Dehydroxylation results in a partial or a total transformation of octahedral co-ordinated aluminum into four-fold coordinated atoms. Stresses arising from sharing adjacent octahedral edges are probably at the origin of the Lewis catalytically active sites.

The research reports reviewed are mainly those issued from the author’s laboratories, or by his correspondents.
Oxidizing Power of the Surface of Attapulgite Clay
Authors: Miller John G. , Haden W. Linwood , Oulton T. Dixon
Published: August 2006

It has been demonstrated that ferric iron is the principal source of the oxidizing action of the surface of attapulgite clay. The extent of oxidizing action in a given time (the oxidizing power) has been determined as a function of the temperature of calcination of the clay in the range 100–900°C.

The oxidizing power was measured with TiCl3 in aqueous acid medium by direct titration of the clay in situ and by titration of extracts of the clay. The dissolution of the metallic cations of the clay was also studied in the same medium. The results have been correlated with structural changes caused by the calcination of attapulgite.
Clay-Mineral Environmental Relationships in Cisco (U. Penn.) Clays and Shales, North Central Texas
Authors: Shover E. F.
Published: August 2006

The clay-mineral composition of 142 samples of Upper Pennsylvania fluvial, deltaic, and marine clays and shales from north Texas was determined by X-ray diffraction. Deltaic lithotypes are of moderate illite, subordinate kaolinite, minor vermiculite and mixed layer composition. Nonmarine (red bed, coaly shales) lithotypes range from this composition to highly (+90 per cent) kaolinitic types, and generally lack vermiculite or chlorite. The marine shales contain a clay-mineral suite which is very similar to that of deltaic beds, but usually contain poorly- to well-crystallized chlorite. These variations are interpreted as results of two opposing mechanisms of clay-mineral genesis: degradation and desilication of detrital clay-micas, and formation of kaolinite, in nonmarine milieux; and regrading of detrital vermiculite to better-crystalline chloritic minerals by magnesium adsorption in marine waters.

The study reveals three pertinent points about clay-mineral environmental relationships:

1.

The potential effects of nonmarine clay-mineral alteration processes are of much greater consequence than are those in marine environments. In this case, they led to the formation of beds in which the clay-mineral suite is almost all kaolinite, whereas the gross qualitative detrital clay-mineral suite was little changed in marine waters.

2.

The actual extent and effect of the clay-mineral formation processes is quite variable, so that there is considerable overlap in clay-mineral composition between nonmarine and deltaic deposits.

(3)

“Trace” clay-mineral constituents may be more sensitive environmental indicators than the gross clay-mineral composition, in this case presence or absence and crystal-Unity of the chlorite-vermiculite component was the most diagnostic parameter.
The Octahedral Layer
Authors: Gastuche M. C.
Published: August 2006

In the first part of this paper the formation processes of pure octahedral hydroxides are investigated. Conditions of synthesis of aluminum, magnesium, iron and mixed Al-Mg, Al-Ca, Al-Fe systems are successively reviewed. In every case crystal growth in deionized medium allows one to figure out genetic conditions.

The second part deals with the conditions required for the development of the octahedral layer in the presence of silica, i.e. the clay mineral synthesis. Experimental conditions remain always as nearly as possible to those observed naturally.

Trioctahedral minerals are rather easily obtained at ordinary temperature and pressure. The evolution of the magnesium-silica system is described. Synthesis of dioctahedral layer lattices, such as those of the kaolin minerals, appears more difficult to perform under the same conditions. Initial organization of the starting materials plays an important role in this case and procedures are described.

Finally, interactions of octahedral and silica layers are studied. The study of infrared spectra in the 9–11μ region permits such observations. Characteristic changes in the spectral region of Si-O stretching allows one either to follow the octahedral destruction (by acid attack or dehydroxylation) or the octahedral layer formation in kaolinite synthesis.
Clay Mineralogy and Weathering of a Red-Yellow Podzolic Soil from Quartz Mica Schist in the Alabama Piedmont
Authors: Bryant J. P. , Dixon J. B.
Published: August 2006

Mineralogical and chemical properties of Madison soil derived from quartz mica schist reflected the degree of weathering. The Madison soil had sandy surface horizons and clayey B horizons. The clay in surface horizons contained more mica than clay in the subsoils; a maximum of about 40 per cent mica in the coarse clay of surface horizons. Intergradient chlorite-vermiculite was present in appreciable quantities in clays of surface horizons. The presence in the whole soil of B2 horizons of about 15 per cent gibbsite and 12 per cent free iron oxides indicated a high degree of weathering. Kaolinite and gibbsite increased with depth and were the major clay minerals in all clay fractions in the lower portion of the profiles. Kaolinite and gibbsite also were important accessory minerals of the coarse and medium silt fractions and increased in percentage with depth. The B3 horizons had much of the morphology of the schist. Results indicated a high weathering intensity in the subsoil and leaching of weathering products.
Preparation and Properties of Some Polymer-Clay Compounds
Authors: Dekking Henri G. G.
Published: August 2006

Novel polymer-clay compositions were synthesized by neutralizing hydrogen montmorillonite and hydrogen kaolinite with amine-terminated polystyrene. The latter was obtained by the amide ion-initiated polymerization of styrene in liquid ammonia at −33°C. The neutralization reactions were carried out in methyl ethyl ketone, acetone, N,N-dimethylformamide and their aqueous solutions. As a result of their chemical modifications, the clays change from hydrophilic to hydrophobic, organophilic substances. Polystyrene-montmorillonite compositions containing about 50 per cent by weight of combined polymer formed dispersions in hydrocarbon oils which were similar to high temperature lubricating greases. The basal spacings of the organo-montmorillonites indicate the deposition of a polymer layer one molecule thick.
Interstratification in Montmorillonite
Authors: Tettenhorst Rodney , Johns W. D.
Published: August 2006

Direct analysis by Fourier transform methods revealed
interstratification of three components for a homogeneous, potassium-treated
and organic-solvated montmorillon-ite. An initial simple interpretation
based on random mixing of two components was shown to be incorrect. Ethylene
glycol solvation showed enhanced expansion in agreement with earlier
investigations. Glycerol solvation produced a noteworthy contribution from a
14 Å component. An interpretation of the 14 Å component is suggested, based
on an asymmetric distribution of layer charge. Regular interstratification,
bending or curling of clay layers and anomalous dehydroxylation temperatures
may be a consequence of asymmetric layer charge distribution in
montmorillonites.
Authigenic Kaolinite and Mica as Evidence for Phase Equilibria at Low
Temperatures
Authors: Rex R. W.
Published: August 2006

Electron micrograph, X-ray diffraction, and chemical
studies of secondary clay minerals formed within sandstones provide data
supporting a portion of the phase relationships proposed by Garrels (Garrels
and Christ, 1965) for kaolinite and K-mica growing in equilibrium with
K-feldspar and quartz at about 25°C. A true phase distinction between mica
and kaolinite is found at the phase boundary and not a continuous
solid-solution series, such as proposed by Keeling (1961). Some of the
micas, however, show evidence for the presence of an interlayer impurity,
such as small amounts of hydroxymagnesium cation proxying for
K+. Electron micrographs and diffraction studies
show epitaxial growth of oriented mica crystals on kaolinite providing
evidence for the existence of these two distinct phases in mutual
equilibrium with the solution from which they crystallized.
Expansion and Electrical Conductivity of Montmorillonite in Ammonia
Atmosphere
Authors: Cloos P. , Mortland M. M.
Published: August 2006

The expansion of montmorillonite at various relative
pressures of ammonia up to saturation was shown to be markedly affected by
the kind of ion present on the exchange complex. A 12.3 Å spacing was
obtained with Li-, Na-, K-, Mg- and Ca-montmorillonites at low relative
pressures. This spacing was maintained up to saturation for the K and Mg
systems and apparently represents one layer of ammonia in the interlamellar
spaces. For Li-, Na- and Ca-clay, two layers of ammonia were formed at
higher relative pressures. In the cases of Cu- and Co-montmorillonite,
rational spacings at 12.8 and 15.1 Å respectively were obtained at low
relative pressures and were maintained to saturation. The results are
interpreted in terms of co-ordination complex formation.

Electrical conductance studies showed exponential increases in
conductivity as the relative pressure of ammonia increased. The apparent
activation energies showed decreases with increase in relative pressure for
all systems except Co- and Mg-clay, which remained rather constant over the
pressure range studied. The results indicated that both expansion and
electrical conductivity were influenced by the formation of the ammonium ion
and by the co-ordinating power of the exchangeable cation.
Infrared Study of Pyridine Adsorbed on Montmorillonite Surfaces
Authors: Swoboda A. R. , Kunze G. W.
Published: August 2006

The nature of pyridine adsorption by acid- and
base-saturated montmorillonite from Otay, California (A.P.I, no. H-24) was
studied by infrared adsorption. The spectrum for chemisorbed pyridine was
found to be distinctively different from physically adsorbed pyridine; the
latter gave a spectrum very similar to liquid pyridine. Upon exposure of the
clay films to pyridine at low vapor pressures, only the pyridinium ion
spectrum was obtained; but when the vapor pressure was increased, both
chemisorbed and physically adsorbed pyridine was detected. The intensity of
the spectrum for physically adsorbed molecules could be reduced by a vacuum,
whereas the intensities of the peaks for the chemisorbed pyridinium ions
were unaffected.

Interlayer water was replaced by adsorption of pyridine. Water, in turn,
replaced physically adsorbed pyridine from the clay surface but was unable
to replace chemisorbed pyridine.
Infrared Studies of the Hydroxyl Groups in Intercalated Kaolinite
Complexes
Authors: Ledoux Robert L. , White Joe L.
Published: August 2006

Expansion of kaolinite with potassium acetate reduces
the intensity of the 3695 cm−1 absorption band and
causes the appearance of an additional one at 3600
cm−1. Subsequent deuteration with
D2O vapor shifts the 3695 cm−1
and 3600 cm−1 absorption bands to 2725
cm−1 and 2650 cm−1
respectively. The hydroxyls absorbing at 3620 cm−1 do
not interact with the acetate anion and do not readily exchange with
D2O vapor.

Deuteration of expanded hydrazine-kaolinite complex at room temperature
shifts the infrared stretching frequencies 3695, 3670, 3650 and 3620
cm−1 to 2725, 2710, 2698 and 2675
cm−1 respectively. The OH-OD exchanges for the
hydroxyls absorbing at 3695, 3670 and 3650 cm−1 are 67,
60 and 62 per cent respectively, and for the 3620 cm−1
only 22 per cent. The 3695, 3670 and 3650 cm−1
absorption bands are correlated predominantly to inner-surface hydroxyls and
the 3620 cm−1 to inner hydroxyls located below the
holes in the silica tetrahedral layer.

The ν(OH) absorption bands at 3695, 3670 and
3650 cm−1, and the ν(OD) at
2725, 2698, and 2675 cm−1 are pleochroic, whereas the
3620 cm−1 absorption band is non-pleochroic. The
direction of the dipole moment change of OH groups absorbing at 3695
cm−1 and 3670 cm−1, and of OD
groups absorbing at 2725 cm−1 and 2698
cm−1, is nearly at right angles to the basal plane
(001); for the 3650 cm−1 and 2675
cm−1 bands, the angle is large, but less than 90°.
The inner hydroxyls absorbing at 3620 cm−1 have their
dipole moment change inclined at about 15° to the “ab” cleavage
plane.

A comparison of the ν(OH) and
ν(OD) absorption intensities for the film
rotated 45° and normal to the infrared incident radiation shows that the
pleochroism is more intense in the ν(OD) region
than in the ν(OH) region. This indicates that
partial deuteration perturbs the direction of dipole moment change of the
“hydrogen bond” with respect to the initial orientation prior to
deuteration; the net result is the formation of larger angles between the
direction of the OD dipole moment changes and the basal plane (001) than
existed for OH prior to deuteration.
Use of Negative Sorption in Studies of Ion Fixation By
Hydrobiotite
Authors: Jacobs Donald G.
Published: August 2006

The exclusion of anions relative to tritiated water
from the negatively charged interlamellar spacing of hydrobiotites that have
a limited degree of lattice expansion permits measurement of the
interlamellar volume. Measurement of the changes in the interlamellar volume
and in the exchange capacity, when hydrobiotite lattices are collapsed by
potassium treatment or expanded by treatment with sodium tetraphenyl boron,
provides a means for estimating the distribution of the surface charge
densities of these interstratified minerals.

In the hydrobiotite sample studied (Zonolite from Traveler’s Rest, South
Carolina), the biotite fraction was estimated to have a surface charge
density of 2.0 ± 0.14 × 10−7 meq
cm−2 and the vermiculite fraction, 1.5 ± 0.51 ×
10−7 meq cm−2. The charge
density, and its relative distribution, was reflected in the tendency of
these mineral fractions to collapse upon potassium treatment and to entrap
trace concentrations of cesium in the interlayer spacing.
Modification of Ca-Montmorillonite by Low-Temperature Heat
Treatment
Authors: Ho Clara , Handy R. L.
Published: August 2006

The objectives of this investigation were to measure
the effects of moderate heat treatments, below the dehydroxylation
temperature, on physical and chemical properties of a
calcium-montmorillonite clay. Previous workers have noted the reductions in
cation exchange capacity and swelling property after heating in the range
200°–400°C, and have suggested several possible explanations, such as
hysteresis effect, increased interlayer attractions owing to removal of
interlayer water, or changes in the disposition of interlayer or
layer-surface ions.

The liquid limits of Ca-montmorillonite steadily decreased with
increased treatment temperature, until they reached a constant level at 450°
to 500°C. The plastic limit decreased slightly up to 350°C. Above this
temperature samples could no longer be rolled into threads. The gradual
change is in contrast with sudden major changes noted for weight loss
(maximum rates of change at 100°C and 500°C), glycol retention surface area
(maximum change at 520°C), and changes of peak intensity and breadth
character after glycolation of the first diffraction maximum (530°C). Other
properties showing more gradual reductions with heat treatment were: cation
exchange capacity by NH4Ac method,
d001 intensity (21 Å
spacing) after storing at 100 per cent r.h. one month and re-wetting with
water, and amount of calcium exchangeable without water soaking. Previous
water soaking allowed much greater release of fixed
Ca++ up to 450°C. Similar results were obtained
with cation exchange capacities when samples were treated with In
CaCl2 solution.

The 21.0 Å peak intensity curve showed close similarity to the liquid
limit and plastic index curves in the low temperature range, and an
explanation is suggested.
Effect of Impurities on the Rheology of Two Kaolins
Authors: Langston R. B. , Jenne E. A. , Pask J. A.
Published: August 2006

Two kaolins were given five successive processing
steps designed to remove a number of impurities: (1) removal of nonclay and
soluble fractions; (2) removal of organic material; (3) removal of iron
oxides; (4) removal of allophane; and (5) removal of three- layer lattice
minerals. After each of these steps, consistency curves were obtained for
each of the clays at both 6.5 and 9.0 pH on slurries containing up to 50
weight % solids.

Photomicrographs and electron micrographs showed that Ka-7 from Bath,
South Carolina, contained generally smaller particles than Ka-2 from Macon,
Georgia. Lowering the pH from 9.0 to 6.5 in Ka-2 produced no change in
plastic viscosity at the lower concentrations and a decrease of about 30 per
cent at higher concentrations after processing step 1. A comparison of the
same evaluations of step-1-treated Ka-7 showed that the decrease in pH
reduced the plastic viscosity by 50 per cent at 5 per cent clay
concentration and increased the plastic viscosity by 100 per cent at 35 per
cent clay concentration. After complete processing, lowering the pH from 9.0
to 6.5 increased the plastic viscosity at all concentrations for both
kaolins by 5–20 per cent. At a clay concentration of 30 per cent, complete
processing decreased the plastic viscosity of Ka-2 from 0.4 to 0.02 poise
and of Ka-7 from 0.4 to 0.06 poise. Ka-7 showed progressive viscosity
changes due to the processing, while Ka-2 showed only a marked change in
viscosity for processing step 5. The rheological changes of Ka-2 and Ka-7
with processing are supported by the X-ray diffraction data at the various
processing stages. X-ray diffraction data confirm that processing step 5
effectively removed a three-layer lattice expandable mineral from Ka-2,
while processing step 3 effectively removed a different three-layer
expandable mineral from Ka-7.
Quantitative Analysis of Kaolinite and Gibbsite in Soils by Differential Thermal and Selective Dissolution Methods
Authors: Dixon J. B.
Published: August 2006

Clay fractions from four soils were analyzed for kaolinite and gibbsite by differential thermal analysis (DTA) and selective dissolution analysis (SDA). The kaolinite values by the two methods had a standard deviation of ±0.95 for the 2–0.2 μ clay of the three most highly weathered soils. Apparently some kaolinite was dissolved with amorphous material in the 0.2–0.08 μ kaolinite standard and probably in 0.2-0.08 μ soil clays. Accuracy of kaolinite determination for the 0.2–0.08 μ soil clays by DTA was reduced because of uncertainty of exact composition of the standard. Presence of montmorillonite in Sango soil clays, particularly the 0.2-0.08 μ fraction, apparently contributed to the error in kaolinite determination by SDA. More precise values for gibbsite were obtained by DTA than by SDA because of the dissolution of alumina from sources other than gibbsite.
Concentration of Dioctahedral Mica and Vermiculite using a Fluoride Solution
Authors: Rich C. I.
Published: August 2006

A Solution containing fluoride (0.4 n NH4F, 0.1 n HCl, n NH4Cl), permits the concentration of dioctahedral mica and dioctahedral vermiculite in mixed clay systems. Allophane, halloysite, kaolinite, and in particular, Mg-rich montmorillonite, biotite, and vermiculite of clay size, are destroyed in 24–48 hr at room temperature. A salt-free, NH4-saturated sample, weighing 80 mg, is shaken in 80 ml of the fluoride solution. The residue is washed with water and X-ray diffraction patterns made.

The method has use in characterizing some of the 2:1 layer silicates in clays. Anatase, if present, is also concentrated and is more positively identified by X-ray diffraction.
Electrostatic forces Between Clay and Cations as Calculated and Inferred from Electrical Conductivity
Authors: Shainberg I. , Kemper W. D.
Published: August 2006

Equivalent conductivities of adsorbed cations were determined in clays saturated with Na+, Cs+, Ca++ and with mixtures of these cations. Measurements were also made on Ca++ clays which had been forced by previous drying into bundles of platelets or tac-toids. The average mobility of adsorbed Ca++ and Cs+ is much lower than that of adsorbed Na+.

It was concluded that the average mobility of adsorbed Ca++ is low because most of this Ca++ is on the internal surfaces of tactoids. Ca++ adsorbed between these internal surfaces appears to have a mobility much lower than Ca++ on the external surfaces which has a mobility of the same order of magnitude as Na+. Polarization of adsorbed Cs+ accounts at least partially for its low mobility in these clays.

Demixing of adsorbed cations (segregation with Na+ dominant between some platelets and Ca++ between others) is suggested as an initial step leading to breakup of a Na+-Ca++ clay mass into tactoids. The tactoid model, with Ca++ and Na+ preferentially on the internal and external surfaces respectively, furnishes an explanation of the instability of clay and soil aggregates with 15% exchangeable sodium.
Quantitative Study of Clay Minerals in Some Recent Marine Sediments and Sedimentary Rocks from Japan
Authors: Oinuma Kaoru , Kobayashi Kazuo
Published: August 2006

Clay mineral compositions in specimens of Recent marine sediments in the neighbourhood of Japan and sedimentary rocks from Japan were studied. Identification of the clay minerals was made chiefly by X-ray, differential thermal and infrared analyses. Their relative amounts were determined by comparing the intensities of their basal X-ray reflections.

Recent marine sediments: Specimens from the bottom of the Northwestern Pacific Ocean contain montmorillonite, illite, chlorite and kaolinite. The amount of mont-morillonite varies locally, but that of kaolinite is generally small. Clay mineral compositions of the Eastern Sea specimens are different from those of the Northwestern Pacific Ocean and the crystallinity of clay minerals seems to be better in the Kastern Sea. It is most likely that the clay minerals in the Eastern Sea sediments were supplied from the continent. Specimens of the bottom sediments at the entrance of Tokyo Bay contain montmorillonite, illite, chlorite and a lesser amount of kaolinite. The amount of montmorillonite varies markedly with locality and tends to be low where the movement of sea water is relatively intense. This may be due to a finer particle size of montmorillonite in comparison with the other clay minerals.

Sedimentary rocks: The relationship between sedimentary formations and clay mineral compositions shows that the compositions are characteristic of the depositional environments. For example, kaolinite is abundant in the formations deposited in fresh water but its content is low in the formations deposited under marine environment. The Paleozoic formations from the Tohoku region contain chlorite and illite without exception; however, the Mesozoic formations contain them in various proportions according to localities.
Clay Minerals in Recent Sediments of the Niger Delta
Authors: Porrenga D. H.
Published: August 2006

Recent sediments of the Niger delta contain the detrital clay minerals kaolinite, mont-morillonite and a small amount of illite. The montmorillonite content increases with water depth and distance from the shore, and the results of laboratory experiments on natural Niger delta clay support the assumption that this is due to differential floc-culation and sedimentation.

The easterly Guinea Current, transporting montmorillonite-rich floccules in suspension, may cause an increase in the montmorillonite content of the clays in the ©cistern part of the delta.

Mineralized faecal pellets are present in most marine sediment samples. Chamosite occurs authigenically in coastal water shallower than 35 fathoms, as brown and dark-green pellets. Green pellets, composed of highly expandable, montmorillonite-type glauconite, are particularly common around the 100 fathom isobath. Both chamosite and glauconite have a high magnesium content, which seems to be usual during their early stages of formation.

The formation of chamosite and glauconite is governed by redox potential and the availability of iron. If no reduction takes place, the pellets remain grey and their composition is similar to that of the clay matrix. Grey pellets are less restricted to a particular depth than are the chamosite and glauconite pellets, but distinct maxima occur around the 250 fathom isobath.
Clay Mineral Formation in Sea Water by Submarine Weathering of K-Feldspar
Authors: Rex R. W. , Martin B. D.
Published: August 2006

A suite of granodiorite samples was collected by dredging from depths of about 1000 m from the walls of Carmel and Monterey submarine canyons, Monterey Bay, California. One surface of each of the various granodiorite slabs was weathered and encrusted with marine organisms. The weathering is maximum at the surface and penetrates to a depth of about 20 cm and selectively alters the feldspars to clay. Potassium feldspars are most severely altered. Mineral selective attack, shallow depth of weathering, restriction of biological growth to weathered surfaces, and regional geological setting are interpreted to mean that the samples were broken from bedrock and that this granodiorite probably weathered in the marine environment.

Authigenic clays formed as a result of the submarine weathering of the granodiorite are kaolinite, K-mica, montmorillonite, and halloysite.

These data suggest that the assemblage K-mica, montmorillonite, and kaolinite have a phase join that may lie on or close to the composition of sea water. Furthermore, kaolinite may be unstable in sea water and gradually break up to form halloysite tubes. The possible influence of biologie agents is suggested in the formation of marine halloysite.
The Stability of Brucite in the Weathering Zone of the New Idria Serpentinite
Authors: Mumpton F. A. , Thompson C. S.
Published: August 2006

Petrographic studies have shown that brucite is a major constituent of the New Idria serpentinite and of the short-fiber asbestos deposit associated with it. Acid-leaching data suggest that the serpentinite averages 7–8 weight per cent brucite, which contains approximately 15 mole per cent “Fe(OH)2”. Unit cell parameters and electron probe analysis suggest an empirical formula close to (Mg10Fe2)(OH)24 for this phase. Brucite formed during the initial serpentinization of an olivine-rich parent and is concentrated today in the hard, dense serpentinite fragments scattered throughout a highly sheared matrix of soft, friable asbestos. Although brueite is abundant in the fresh serpentinite it is almost absent from the surface weathering zone, which persists to a depth of 20–30 ft across the entire body. Here, serpentinite fragments have oxidized and brueite has transformed in situ into pyroaurite [Mg6Fe2CO3(OH)16.4H2O] and a new mineral, coalingite [Mg10Fe2CO3(OH)24.2H2O]. Brueite in the matrix material has dissolved in the CO2-rich ground waters, yielding soluble magnesium ions and amorphous iron oxides which discolor the surface asbestos.

In the laboratory, samples of fresh serpentinite oxidized and disintegrated completely when exposed to the atmosphere for a few months, due to the brucite-coalingite transformation. In the presence of O2 and CO2, brueite dissolved completely from a water slurry of the serpentinite, yielding a dark brown residue and a clear filtrate which later precipitated hydromagnesite [Mg4(OH)2(CO3)3.3H2O]. These data indicate that in the relatively impervious environment of the residual serpentinite “boulders”, iron-rich brueite oxidizes in air, picking up CO2 and H2O to form coalingite. In the presence of excess ground waters, brueite in the friable matrix dissolves, leaving behind a residue of amorphous iron oxides. Dissolved magnesium ions later precipitate as hydromagnesite, which is also abundant in the surface weathering zone of the serpentinite.
Relation of Viscosity of Kaolin-Water Suspensions to Montmorillonite Content of Certain Georgia Clays
Authors: Iannicelli J. , Millman N.
Published: August 2006

The viscosity of certain kaolin—water systems was correlated with natural montmorillonite content of the kaolin, as determined quantitatively by the Hinckley—Bates (1960) strontium-exchange technique. Transition from low viscosity to high viscosity occurred when montmorillonite content of the Georgia clays studied exceeded 5%.
Formation Damage in Sandstones Caused by Clay Dispersion and Migration
Authors: Gray D. H. , Rex R. W.
Published: August 2006

X-ray diffraction and electron microscopy were employed in conjunction with core flooding experiments to investigate clay migration phenomena.

Severe water sensitivity or loss of permeability was observed in a suite of sandstones in spite of the almost total absence of montmorillonite or swelling mixed layer clays. Clay migration was found to cause total or partial plugging even in sandstones of 500 millidarcy permeability. Bacterial plugging was ruled out by prefiltering and bactericide treatments of waters.

X-ray diffraction and electron microscopy analyses were performed on the sandstones and produced effluents. The direct cause of damage was displacement of submicroscopic natural clay crystals of needle-shaped mica and hexagonal-shaped kaolinite (Rex, 1965). The mobile clays were identified as authigenic crystals that are present on the pore walls and are dislodged by changes in water chemistry combined with water movement.

Flooding sandstones with alkali metal brines “sensitized” the cores, i.e. triggered clay dispersion upon subsequent flooding with fresh water. Flooding with divalent calcium brine prevented water sensitivity and suppressed the undesirable effect of alkali metal brines. A double layer expansion effect is suggested as the dispersion mechanism.
Infrared Analysis of the Orientation of Pyridine Molecules in Clay Complexes
Authors: Serratosa J. M.
Published: August 2006

Infrared spectroscopy affords a useful method for the determination of the orientation of molecules sorbed on layer silicates. The orientation of the molecules can be inferred from the observed dichroism of specific absorption bands. Examples of the analysis are illustrated in three complexes with pyridine. One flat and one vertical orientation are observed for the ionic form dependent on layer charge. A different vertical orientation is observed for the neutral molecule. The interpretation of the infrared absorption analysis is confirmed by X-ray diffraction.
Separation of Swelling Clay Minerals by a Centrifugal Method
Authors: Bush Darrell C. , Jenkins Ralph E. , McCaleb Stanley B.
Published: August 2006

Total, slightly, and highly swelling clay minerals can be separated and measured by the test procedure described. Separations of synthetic mixtures of essentially pure natural sediments indicate that the measurements are accurate within ± 1% of the true values for samples containing < 20% swelling clays, and that < 1% quantities can be detected. Test results using < 5 micron material show that small grain size is not a problem in effective separation.

The test procedure is primarily a centrifuge separation based on the hydrated grain densities of the swelling clay minerals. The sample grains are pretreated with silicone (Dow 1107). The swelling clays are separated from rock and soil samples by centrifuging the sample-water slurry over a non-water-miscible heavy liquid. The sample is stirred violently at and above the water-heavy liquid interface during this centrifuging. The desired swelling clay fraction is recovered in the water medium and the denser minerals are collected in the heavy liquid. Water-soluble minerals are removed by filtering. Quantitative measurements are based on dry weights.

Application of this method to petroleum engineering and geology is stressed, but other disciplines will have use for the described procedure.
Successes and Challenges in Preventing Conduct Problems in Australian Preschool-Aged Children Through the Early Impact (EI) Program
Authors: Larmar Stephen , Dadds Mark R. , Shochet Ian
Published: August 2006

This article reports on the initial effects of the Early Impact (EI) Program, a preventative program that includes home and school components designed to arrest the development of conduct problems in preschool-aged children. Participants included 455 preschool-aged children enrolled across 10 schools. Schools were randomly assigned to either EI or control conditions. All participants were screened at the commencement of the academic year to determine those children considered more at risk for ongoing conduct problems. Following screening n = 66 children were identified in the intervention group and n = 69 in the control. The intervention commenced in the second term of the academic year and ran over a 10-week period. Teachers involved in the intervention were highly engaged and satisfied with the program design. Improvements were reported at the school level at post-intervention with mixed evidence of durability of change at 6-month follow-up. Parent participants were more difficult to engage and reported no changes in the behaviour of children in the home. The study provides initial evidence of the efficacy of the EI intervention as a means of preventing conduct problems in young children at the school level; however, issues associated with parental engagement and home-based change remain to be solved.
Influenza rapid tests – advantages and limitations / Influenza-Schnelltests – Vorteile und Grenzen
Authors: Schweiger Brunhilde
Published: August 2006

The recent advent of new treatments (neuraminidase inhibitors) for influenza has stimulated the development of rapid diagnostic methods because these treatments have shown a clinical benefit only when administered early in the course of the disease. In Germany, at least ten different rapid enzyme-linked immunosorbent assay kits are available as “near patient test” for the diagnosis of influenza viruses. Classical viral culture methods and immunofluorescence staining of antigens in patient specimens were used in most studies as a reference to analyze the performance of rapid influenza tests. The different tests had sensitivities ranging from 50 to 96% and specificities ranging from 72 to 100%, respectively. The test characteristics mainly depended on the type of test, the type and processing of clinical specimen, and the age of the patient. Although the sensitivity of the rapid diagnostic tests is lower compared to that of virological and molecular methods, the positive predictive values indicate that rapid testing may be helpful for patient management, including the prompt administration of appropriate antiviral therapy, as well as for assistance in isolating patients in hospitals and long-term-facilities to reduce the spread of infection and for the surveillance of influenza.
CE-Kennzeichnung von Point-of-Care-Testsystemen / CE marking of point-of-care test devices
Authors: Nübling Micha
Published: August 2006

Point-of-Care-Tests (POCT) stellen eine Gruppe innerhalb der In-vitro-Diagnostika (IVD) dar. Die Verkehrsfähigkeit von IVD im gemeinsamen europäischen Markt wird durch das CE-Kennzeichen ausgedrückt, das die Übereinstimmung des Tests mit den Vorgaben der europäischen IVD-Richtlinie dokumentiert. POCT unterliegen prinzipiell denselben Anforderungen wie alle anderen Labor-IVD. Die CE-Kennzeichnung wird vom Hersteller angebracht, der damit bestätigt, dass das betreffende Produkt den grundlegenden Anforderungen der Richtlinie entspricht und einem in der Richtlinie vorgesehenen Konformitätsbewertungsverfahren unterzogen wurde. Der Hersteller wird bei der CE-Kennzeichnung bestimmter IVD, deren möglicherweise inkorrektes Testergebnis mit einem höheren Risiko für Patient oder Dritte verbunden sein kann, von einer benannten Stelle unterstützt. Die Marktüberwachung CE-gekennzeichneter IVD wird durch nationale Behörden wahrgenommen, die bei Vorkommnissen Maßnahmen festlegen können.
Diagnosekriterien für das Antiphospholipid-Syndrom (APS) / Diagnostic criteria for the antiphospholipid syndrome (APS)
Authors: Philipp von Landenberg Arbeitsgruppe Autoimmundiagnostik / Im Namen der Mitglieder
Published: August 2006

Die Diagnostik des Antiphospholipid-Syndroms (APS) stellt nach wie vor eine Herausforderung sowohl für den Kliniker als auch für den Labormediziner dar. Neben der mangelnden Standardisierung der Antikörper-Tests stellt insbesondere die Assoziation der Antiphospholipid-Antikörper mit verschiedensten Infektionen ein schwerwiegendes diagnostisches Problem dar. Auch die Vielfalt möglicher Symptome, die mittlerweile in Assoziation mit dem Antiphospholipid-Syndrom beschrieben wurden, erschwert eine frühe Diagnose. Im Folgenden soll ein Algorithmus zur Diagnose des APS beschrieben werden, der in der Arbeitsgruppe für Autoimmunität der Deutschen Vereinten Gesellschaft für Klinische Chemie und Laboratoriumsmedizin (DGKL) erarbeitet wurde. Bei Verdacht auf das Vorliegen eines Antiphospholipid-Syndroms sollte neben der “klassischen” Gerinnungsdiagnostik auch die Suche nach Antiphospholipid-Antikörpern begonnen werden. Insbesondere der Umgang mit grenzwertigen Ergebnissen und die weitere Diagnostik bei initial negativen Antikörper-Befunden werden im Detail diskutiert. Ziel ist es, sowohl dem Kliniker als auch dem Labormediziner eine Hilfestellung zur effektiven Diagnostik des Antiphospholipid-Syndroms zu geben.
Die medizinische Bedeutung von Selen / The clinical relevance of selenium
Authors: Gärtner Roland
Published: August 2006

Selen ist ein essentielles Spurenelement, das für viele Organfunktionen bedeutsam ist. Es ist nicht, wie früher angenommen, ein einfaches Antioxidans. Selen wird als Selenocystein, die 21. Aminosäure, in das aktive Zentrum von Selenoproteinen eingebaut. Die Synthese dieser Selenoproteine ist abhängig von der täglichen Selenaufnahme. Einige klinisch wichtige Krankheiten, die man in einen Zusammenhang mit einer niedrigen Selenzufuhr bringen kann, werden in dieser Übersicht diskutiert.

Eine ausreichende Selenversorgung ist wichtig für die Immunregulation und kann die Virulenz bestimmter Viren abschwächen. Bei Patienten mit schwerer Sepsis sind die Selenspiegel erniedrigt, und eine hochdosierte Selensubstitution kann die Mortalität signifikant senken. Die Schilddrüse gehört zu den Organen mit dem höchsten Gehalt an Selenoproteinen. Selenmangel führt zu einer erhöhten Inzidenz von Autoimmunerkrankungen der Schilddrüse und eine Selensubstitution kann die entzündliche Aktivität verringern. Selenmangel scheint mit einem erhöhten kardiovaskulären Risiko einherzugehen; inwieweit eine Substitution eine protektive Wirkung auf das kardiovaskuläre System hat, ist bislang nicht gezeigt worden. Auch ein erhöhtes Karzinom-Risiko bei niedriger Selenaufnahme ist epidemiologisch belegt, gute Interventionsstudien fehlen aber bislang; die Ergebnisse der bisher größten Studie hierzu, der SELECT-Studie, müssen abgewartet werden. Selenoproteine scheinen auch eine wichtige Rolle im Zentralnervensystem zu spielen. Immer mehr Erkenntnisse aus der Grundlagenforschung belegen die Bedeutung von Selen für die menschliche Gesundheit.
The Monitoring of Crystallite Size By an X-Ray Method Applicable to the Processing and Synthesis of Micron-Sized Powders
Authors: Johnson LA , McCauley RA
Published: August 2006

An X-ray method for determining the crystallite size of powders is presented that aids in a quick monitoring of powder processing and synthesis of micron-sized powders. The method is helpful in the range of tens of microns to micron sizes. The excellent counting statistics of the X-ray method compares favorably over microscopic methods in its efficiency and ability to characterize the powder in terms of its crystallite size. An albite (NaAlSi3O8) powder that originally showed a distribution of grain sizes was ball milled to a uniform micron size and micron-sized forsterite (Mg2SiO4) was synthesized by a solid-state method using ball milling for mixing of reactants.
Vollständige Modale Synthese im Frequenzbereich (Complete Modal Synthesis in the Frequency Domain)
Authors: Deutscher J. , Hippe Peter
Published: August 2006

Die Vollständige Modale Synthese, d.h. die Reglerberechnung aus den Eigenwerten und den invarianten Parametervektoren einer Regelung, wurde bisher ausschließlich im Zeitbereich formuliert. Dieser Beitrag stellt nun die äquivalente Parametrierung von Zustandsrückführungen im Frequenzbereich vor. Grundlage hierfür ist die Nennermatrix N
˜(s) der Regelung, anhand der eine Zustandsrückführung im Frequenzbereich parametriert werden kann. Für sie lässt sich ein expliziter Ausdruck in Abhängigkeit der Regelungseigenwerte und der zugeordneten Polrichtungen angeben. Diese Polrichtungen sind eng mit den invarianten Parametervektoren der Vollständigen Modalen Synthese verknüpft, so dass sich ein direkter Zusammenhang zwischen der hier vorgeschlagenen Parametrierung einer Zustandsrückführung im Frequenzbereich und der bekannten Zeitbereichsparametrierung angeben lässt. Auf Basis der neuen Parametrierung lässt sich zudem die Auswertung der Zeit- und Frequenzbereichsentwurf verknüpfenden Beziehung zwischen Zustandsrückführmatrix K und Nennermatrix N
˜(s) der Regelung vereinfachen. Ein einfaches Zahlenbeispiel gibt abschließend erste Hinweise auf neue Entwurfsmöglichkeiten, die sich mit der Vollständigen Modalen Synthese im Frequenzbereich eröffnen.
Flachheitsbasierte Randsteuerung parabolischer Systeme mit verteilten Parametern (Flatness-based Boundary Control of Parabolic Distributed Parameter Systems)
Authors: Lynch A.F. , Rudolph Joachim
Published: August 2006

Für durch lineare oder nichtlineare parabolische partielle Differentialgleichungen beschriebene Ausgleichsprozesse werden Randsteuerungen für Übergänge zwischen stationären Profilen berechnet. Die Methode basiert auf einer Flachheitseigenschaft des Systems: Die Lösung, beispielsweise eine orts- und zeitabhängige Temperatur, kann durch einen sogenannten flachen Ausgang beschrieben werden, in diesem Fall durch einen Randwert. Die Berechnungen basieren auf Potenzreihendarstellungen, in denen Zeitableitungen beliebiger Ordnung des flachen Ausgangs auftreten. Die Konvergenz wird durch die Wahl einer nicht-analytischen sogenannten Gevrey-Funktion als Trajektorie für den flachen Ausgang sichergestellt.