bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment of aneurysmal bone cysts with percutaneous sclerotherapy using polidocanol
Authors: Rastogi S. , Varshney M. K. , Trikha V. , Khan S. A. , Choudhury B. , Safaya R.
Published: August 2006

Aneurysmal bone cyst is a rare tumour-like lesion which develops during growth. Our aim was to determine the efficacy of the administration of percutaneous intralesional 3% polidocanol (hydroxypolyaethoxydodecan) as sclerotherapy.

Between July 1997 and December 2004 we treated 72 patients (46 males, 26 females) with a histologically-proven diagnosis of aneurysmal bone cyst, at various skeletal sites using this method. The sclerotherapy was performed under fluoroscopic guidance and general anaesthesia or sedation and local anaesthesia. The mean follow-up period was 34 months (26.5 to 80). The patients were evaluated using the Enneking system for functional assessment and all the lesions were radiologically quantified into four grades.

The mean age of patients was 15.6 years (3 to 38) and the mean number of injections was three (1 to 5). Ten patients were cured by a single injection. The mean reduction in size of the lesion (radiological healing) was found to be 76.6% (61.9% to 93.2%) with a mean clinical response of 84.5% (73.4% to 100%). Recurrence was seen in two patients (2.8%) within two years of treatment and both were treated successfully by further sclerotherapy.

Percutaneous sclerotherapy with polidocanol is a safe alternative to conventional surgery for the treatment of an aneurysmal bone cyst. It can be used at surgically-inaccessible sites and treatment can be performed on an out-patient basis.
Inter-observer reliability and intra-observer reproducibility of the Weber classification of ankle fractures
Authors: Malek I. A. , Machani B. , Mevcha A. M. , Hyder N. H.
Published: August 2006

Our aim was to assess the reproducibility and the reliability of the Weber classification system for fractures of the ankle based on anteroposterior and lateral radiographs. Five observers with varying clinical experience reviewed 50 sets of blinded radiographs. The same observers reviewed the same radiographs again after an interval of four weeks. Inter- and intra-observer agreement was assessed based on the proportion of agreement and the values of the kappa coefficient.

For inter-observer agreement, the mean kappa value was 0.61 (0.59 to 0.63) and the proportion of agreement was 78% (76% to 79%) and for intra-observer agreement the mean kappa value was 0.74 (0.39 to 0.86) with an 85% (60% to 93%) observed agreement. These results show that the Weber classification of fractures of the ankle based on two radiological views has substantial inter-observer reliability and intra-observer reproducibility.
Survivorship of the St Georg Sled medial unicompartmental knee replacement beyond ten years
Authors: Steele R. G. , Hutabarat S. , Evans R. L. , Ackroyd C. E. , Newman J. H.
Published: August 2006

There have been several reports of good survivorship and excellent function at ten years with fixed-bearing unicompartmental knee replacement. However, little is known about survival beyond ten years.

From the Bristol database of over 4000 knee replacements, we identified 203 St Georg Sled unicompartmental knee replacements (174 patients) which had already survived ten years. The mean age of the patients at surgery was 67.1 years (35.7 to 85) with 67 (38.5%) being under 65 years at the time of surgery. They were reviewed at a mean of 14.8 years (10 to 29.4) from surgery to determine survivorship and function. There were 99 knees followed up for 15 years, 21 for 20 years and four for 25 years. The remainder failed, were withdrawn, or the patient had died.

In 58 patients (69 knees) the implant was in situ at the time of death. Revision was undertaken in 16 knees (7.9%) at a mean of 13 years (10.2 to 21.6) after operation. In seven knees (3.4%) this was for progression of arthritis, in three (1.5%) for wear of polyethylene, in four (2%) for tibial loosening, in two (1%) for fracture of the femoral component and in two (1%) for infection. Two knees (1%) were revised for more than one reason.

The mean Bristol knee score of the surviving knees fell from 86 (34 to 100) to 79 (42 to 100) during the second decade. Survivorship to 20 years was 85.9% (95% CI 82.9% to 88.9%) and at 25 years was 80% (95% CI 70.2% to 89.8%). Satisfactory survival of a fixed-bearing unicompartmental knee replacement can be achieved into the second decade and beyond.
Amiodarone Treatment of Junctional Ectopic Tachycardia in a Neonate Receiving Extracorporeal Membrane Oxygenation
Authors: Kendrick Jennifer G , Macready John J , Kissoon Niranjan
Published: August 2006

Objective:

To describe the administration of amiodarone and the resulting serum concentrations in a neonate receiving extracorporeal membrane oxygenation (ECMO).

Case Summary:

A 3463 g, 38 week gestational age male diagnosed with tetralogy of Fallot developed junctional ectopic tachycardia (JET) and required ECMO support following cardiac surgery. The patient continued to show JET despite cooling, pacing, and intravenous amiodarone infusion, with the dose initiated at 10 μg/kg/min. Sinus rhythm was achieved following 5 days of treatment, additional amiodarone boluses, and an increase in the infusion rate to 20 μg/kg/min. Two serum concentrations of amiodarone were obtained during therapy. On day 4, the concentration was 0.9 mg/L at the 20 μg/kg/min infusion rate; a bolus dose of 5 mg/kg was administered 1 hour later. The serum concentration the following day, with the infusion rate unchanged, was 2 mg/L.

Discussion:

ECMO is used increasingly postoperatively in patients with congenital cardiac abnormalities. The incidence of JET following repair of tetralogy of Fallot is 22%. Despite the minimal information on the pharmacokinetics of amiodarone in neonates, it has been used in doses up to 20 μg/kg/min for the treatment of postoperative JET. As of August 25, 2006, we found no reports describing its dosage and use in patients undergoing ECMO.

Conclusions:

The delivery of amiodarone to a patient receiving ECMO may be complicated by the administration of large blood volumes, circuit changes, and binding to the circuit. Neonates receiving ECMO may require larger amiodarone doses to achieve a therapeutic effect. Further investigation is required to define the pharmacokinetics and pharmacodynamics of amiodarone in neonates receiving ECMO.
Size and Shape of Montmorillonite Crystallites
Authors: Jonas Edward C. , Oliver Robert M.
Published: August 2006

Spray drying dilute suspensions of bentonitic montmorillonite produces a powder that shows totally random orientation of the crystallites within a sample large enough to diffract X-rays. The powder is collected by an electrostatic precipitator and can be handled in the normal mounting processes without introducing preferred orientation. Electron micrographs show this powder to be composed on a small scale of thin, crumpled, and rolled films. The extremely small montmorillonite crystallites that make up the film are oriented with [001] directions perpendicular to the film surface. Orientation within the plane of the film is random as shown by selected area electron diffraction. Crumpling and rolling of the film is sufficient to make the orientation of [001] directions random in three dimensions in a large sample when X-ray diffraction is registered.

The X-ray diffraction patterns all show diffraction maxima (both hk and 00l), and their relative intensities with respect to each other can be determined. The line broadening of the 06 and the 003 peaks was studied. The average crystallite size as calculated from the line broadening varied from six to eleven unit layers thick for four bentonitic montmorillonites. The average lateral dimension of crystallites varied from 140 Å to 250 Å. Ratios of lateral dimensions to thickness varied from 2.3 to 3.4.
Electron-Optical Study of Alteration to Smectite in the Cheto Clay Deposit
Authors: Sloane Richard L. , Guilbert John M.
Published: August 2006

Volcanic ash of latitic composition in the Pliocene Bidahochi formation of northeastern Arizona has been altered in place to smectite clay. The Cheto clay, a 4-ft thick bed of high-quality activable smectite, offers an excellent opportunity for electron-optical study of the alteration processes in volcanic glass shards, spherulites, and aggregates in the tuff. No completely unaltered tuff remains in the exposed bed, but transitional materials showing progressive alteration from vitric tuff toward massive smectite have been collected and examined petrographically, electron-optically, and by X-ray diffraction.

The partly altered tuff shows several clearly identified structures relatable to the fresh material: spherical to subspherical spherulites, conchoidally fractured subtriangular to irregular vitric shards dominated by smoothly curved pitted surfaces, massive essentially structureless glass, and columnar fused aggregates which appear interstitial to the shards. Upon alteration these aggregates display an irregular comb-like structure from a planar base in cross-section, and a hackly polygonal to random texture normal to the comb structures. X-ray diffraction reveals only montmorillonite in the materials examined, although minor quartz and plagioclase feldspar have been reported elsewhere in the partially altered ash.

Argillization of the vitric tuff involves several phenomena: (1) the development of layering or banding in the glass; (2) the development of a braided surface aspect perhaps related to banding; (3) the inception of arcuate subparallel lineations on internal curved surfaces of the glass; (4) the growth of pseudohexagonal, weakly curled flakes whose boundaries appear threadlike on glass surfaces, and (5) the growth of grossly hexagonal matted granular networks in completely altered glass. Bladed, comb-like smectite develops along interfaces between glass and more resistant shards and from fused columnar aggregates in the original material. The mechanism appears to be one of essentially pervasive nucleation and growth of smectite in the devitrifying glass with the early development of preferred orientation of individual smectite crystallites. This orientation, manifested in layering and braiding, may reflect simple response to the space problem or response to cryptostruetures and polymerization in the original glass. Relic structures relatable to the unaltered vitric tuff are not obliterated and can be discerned even in the completely altered ash.
X-ray Diffraction Band Profiles of Montmorillonite—Influence of Hydration and of the Exchangeable Cations
Authors: Mering J. , Brindley G. W.
Published: August 2006

Previous studies of diffraction band profiles of montmorillonite are extended to the 13, 20 band which, for reasons discussed, is more sensitive to structural details than the diffraction bands considered previously. Hydration of Na-montmorillonite produces appreciable sharpening of this band, indicating, contrary to previous results, that the water layers have at least a partially ordered arrangement. For Cs-montmorillonite, the single water layer hydrate shows only a small sharpening of the band profile, possibly attributable to the water layer, but which clearly indicates that the Cs ions cannot be significantly displaced from their positions in the anhydrous material. For Ba-montmorillonite, the two-layer hydrate shows a small broadening of the diffraction band, which is possibly the result of a partial ordering of the water layers together with a movement of the Ba ions away from the hexagonal holes.
Order of Mixed-Layering in Illite/Montmorillonites
Authors: Hower John
Published: August 2006

A number of otherwise poorly understood compositional-structural relationships in mixed-layer illite/montmorillonites appear to be explained by ordered interlayering of 2:1 units. The ordering appears to be between high and low charge 2:1 units. The relationship between per cent expandable layers and mean lattice charge in natural materials shows a scatter that is nicely bracketed by hypothetical curves constructed assuming random or completely ordered interlayering for several types of 2:1 charge distribution. Natural samples with 30–50% expandable layers plotting near the “ordered” curves have diffraction peaks at 25 Å for two water layers in the expandable layers and 27 Å with two glycol layers; samples plotting near the “random” curves do not have these peaks and have poorly developed 001/001 reflections.

Some tentative conclusions are: (1) illites are virtually non-expandable at lattice charges significantly less than that of ideal mica because of ordering of high-low charge 2:1 units, (2) illites and mixed-layer illite/montmorillonites with the same mean lattice charge show a range of expandability because of varying degrees of ordering, (3) the highly variable CEC of samples with the same expandability also results from a varying degree of ordering.

An interesting petrological implication results when it is realized that a sample with a given bulk composition can have a wide range of expandability, depending on ordering. Low expandability, achieved by ordering, should be promoted by formation at high pressures. Glauconites, known to form largely at the time of sedimentation, appear to be dominantly randomly interstratified; illites and illite/montmorillonites, which may form on deep burial of argillaceous sediments, are dominantly ordered.
Interstratification in Vermiculite
Authors: Sawhney B. L.
Published: August 2006

Vermiculite (Libby, Mont.) was ground in a Waring blender in a 1 m NaCl solution and, after removal of excess electrolyte, the clay fraction was separated by sedimentation. The clay was predominantly vermiculite: X-ray diffraction patterns of Ca-saturated and oriented specimens showed an intense and sharp 15 Å and a weak 25 Å diffraction maxima and their integral orders. The intensity of the 25 Å reflection, attributed to regularly interstratified layers of vermiculite (15 Å) and mica (10 Å), was less than 20% of the 15 Å peak.

Additions of varying amounts of potassium or cesium, ranging from 10% to 100% of exchange capacity, to Ca-saturated clay showed that the collapse of the vermiculite lattice proceeds through a 1:1 regular interstratification of a 15 Å and a 10 Å lattice. Successive additions increased the 25 Å diffraction peak at the expense of the 15 Å reflection until the entire sample was interstratified. Further additions of K (or Cs) reduced the intensity of the 25 Å reflection and produced a 10 Å reflection until the entire sample was collapsed to 10 Å and no 25 Å reflection was recorded. These observations point out that under certain environmental conditions, the diagenetic formation of micas from vermiculite may proceed through an interstratification of the two in a manner analogous to weathering of biotite to vermiculite through an interstratified stage.

One-dimensional Fourier synthesis from the intensities of the 00ℓ diffraction maxima of the interstratified mixture was carried out. In addition, a mechanism for the formation of the interstratified mixture was postulated: the replacement of Ca by K (or Cs) in one layer reduces the effective negative charge on the adjacent layer. Consequently, the K cannot replace the Ca in this but replaces the Ca in the next layer forming the interstratified mixture.
Compositional Variation of a Vermiculite as Related to Particle Size
Authors: Kerns Raymond L. , Mankin Charles J.
Published: August 2006

A vermiculite regolith sample from Llano, County, Texas, was divided into 16–32, 8–16, 4–8, 2–4, 1–2, ½–1, ¼–½, 1/10-1/4, and 5/100–1/10 micron equivalent spherical diameter size-classes. A well-crystallized vermiculite found in association with the regolith was ground to −400 mesh.

The samples were analyzed by X-ray diffractometry and differential thermal analysis, and cation exchange capacity measurements were made for selected size fractions. Chemical analyses by X-ray fluorescence revealed a systematic increase in silicon with decreasing particle size. An increase in the iron content and a decrease in magnesium were also directly correlated to a decrease in the crystallite size. Aluminum content was constant throughout the range of particle sizes.

X-ray analyses showed that the coarser particles were trioctahedral, whereas the smaller crystallites were dioctahedral. These data were supported by recast formulae based on the chemical analyses. The recast formulae were substantiated by DTA and cation exchange capacity data as being reasonable approximations of actual formulae.

These observations are interpreted as an expression of chemical alteration that clay minerals may undergo in an aqueous environment. The crystallographic, cation exchange capacity, DTA, and swelling properties are a function of the chemical composition of the crystallites. Chemical composition of the crystallites is shown to be directly correlated to particle size.
Viscoelastic Shear Response of a Kaolinite
Authors: Krizek Raymond J. , Franklin Arley G.
Published: August 2006

Recognition of the fact that clays exhibit both viscous and elastic response characteristics has led to the use of the theory of viscoelasticity for describing their mechanical behavior. This paper presents a brief outline of pertinent concepts from this theory to establish a framework for the presentation and interpretation of the experimental results. The experimental program was conducted on a water-washed Georgia kaolin at nominal moisture contents of 50%, 75%, and 100%, and included a series of oscillatory shear tests over a frequency range of two decades. These tests were performed on a Weissenberg Rheogoniometer with a cone-and-plate sample holder; this arrangement produces essentially homogeneous shear strains throughout the specimen.

The experimental results show that the stress-strain response of the clay is frequency-dependent and is definitely nonlinear, even at small strains. The greatest frequency dependence, as manifested in the complex shear modulus and phase angle, occurs in a region characteristic of many polymer systems. The logarithm of the complex shear modulus is found to vary approximately as the water content or consistency of the clay-water mixture.
Particle Arrangements in Kaolin
Authors: Smart Peter
Published: August 2006

An ambiguity in interpretation of electron micrographs of replicas of fracture surfaces of dry clay samples is illustrated, and a method of making ultra-thin sections described. Micrographs of ultra-thin sections of remoulded, consolidated, and sheared kaolin specimens are shown. In unconsolidated specimens random arrangements of particles, or of small groups of particles, were found. In failure zones, in sheared samples, the preferred orientation was parallel to the zone, with, in some cases, a subsidiary zone in which particles were inclined to the main zone. Interparticle contacts were mainly edge-to-edge or face-to-face.
Alcohol-Water Interactions on Montmorillonite Surfaces. I. Ethanol
Authors: Dowdy R. H. , Mortland M. M.
Published: August 2006

Infrared spectroscopic, X-ray diffraction and gravimetric techniques were used so study the vapor phase adsorption of ethanol on homoionic Cu-, Al-, Ca,, Na-, and NH4-montmorillonite films. Equilibration of these films with ethanol vapor at a relative pressure of unity reduced the water content to less than 0.7% (300°C). As dehydration proceeded, the infrared absorption bands of the residual water were observed. Apparent differences between different cation saturations are reconciled by a consideration of the different types of ion-dipole interactions involved. Adsorption isotherms and X-ray diffraction results substantiated the interpretations of the infrared data. Prolonged evacuation did not remove all of the adsorbed ethanol as shown by spectroscopic and gravimetric techniques. Cu-, Al- and Ca-montmorillonite retained 4.5, 7.9, and 4.5 molecules per ion, respectively, while Na- and NH4-clays retained less than one molecule per cation. Ethanol loss occurred rapidly at 40% relative humidity except in the Cu-system where 70 hr were required for complete replacement. These differences indicate that the adsorption and retention of alcohol by montmorillonite is affected by the saturating cation and that alcohol and water compete for the same adsorption sites. Ion-dipole type interactions should thus be considered in adsorption mechanisms of alcohol on montmorillonite.
X-Ray Study of Interactions between Montmorillonite Platelets
Authors: Andrews Donald E. , Schmidt Paul W. , van Olphen H.
Published: August 2006

Small angle X-ray scattering curves have been obtained for a series of Na Wyoming Bentonite clay samples containing 10% clay by weight and NaPO3 in concentrations ranging from 0 to 100 meq/1. From the scattering data, the relative probability of spacings between parallel clay platelets was computed. For the sample containing no NaPO3, the probability distribution showed a relatively broad maximum at an interparticle spacing of about 180Å. As the concentration of NaPO3 increased, the maximum became sharper and occurred for smaller interparticle distances. At NaPO3 concentrations between 25 and 100 meq/1, the position d of the maximum was given approximately by the equation d = 21 + 18.4c-1/2, where d is in angstroms, and c is the NaPOs concentration in eq/1. The similarity of this relation to the dependence of d on the concentration of NaCl (Norrish and Rausell-Colom, 1963; Norrish, 1954) suggests that the interparticle spacing depends primarily on the sodium ion concentration and not on the concentration of the anion. The value of d appears to be independent of whether the gel was prepared by the method of Norrish and Rausell-Colom, in which a dried flake was allowed to come to equilibrium with an electrolyte solution, or whether, as in this investigation, the gel was obtained by centrifuging a dilute suspension. Since the Na ions act to reduce the double-layer repulsion between platelets, while the anions tend to be adsorbed on the platelet edges and thus reduce the edge-to-face linkages (H. van Olphen, 1962), the value of the most probable interparticle distance appears to be determined primarily by the magnitude of the double-layer repulsion, even though other properties of the clay gels, such as the rheological behavior, are governed mainly by edge-to-face attractions.
Deposition of Montmorillonite from Suspension During Flow Through Porous Media
Authors: Curry R. Bruce
Published: August 2006

Sodium-saturated montmorillonite was used to prepare aqueous suspensions of varying concentration between 0.06% and 3.0%. Compacted columns of glass beads and carborundum constituted the porous media. The system was maintained under saturated flow conditions at hydraulic gradients of 2 and 4. In order to study the relationship of clay properties to those of the porous media, the zeta potential of both suspension and media was determined. A mathematical model of the system was developed that would predict the deposition of clay at various depths in the columns, given concentration and flow rate of the suspensions. In order to test this model, a procedure was developed for tagging the clay with 46Sc, sampling the columns, and determining the amount of deposition using a single-channel gamma-ray spectrometer. Using an activity level of 0.15 microcurie per liter of a 1% suspension it was possible to detect reliably 10 mg of clay in a 40 g sample of the porous media. The results indicate two mechanisms operating in the process of removal of the clay from suspension. One of these, interstitial straining, operates at the surface of the porous media column; while the second, a combination of diffusion and gravitational settling, operates below the surface.

The results of this research have potential applications in the solution of engineering problems relating to water resources conservation such as reservoir seepage control, infiltration of sediment-laden water into the soil, and ground water recharge. Also, the results may be important for answering questions concerning pollutant movement into the water supply through porous strata. All the above are examples in which a colloidal suspension is moving into or through porous media; therefore, an improved understanding of the principles of flow of colloidal suspensions in porous media can contribute to the solution of these engineering problems.
Electrokinetic Effects in Kaolin-Water Systems. I. The Measurement of Electrophoretic Mobility
Authors: Olivier J. P. , Sennett Paul
Published: August 2006

A new apparatus for the measurement of electrophoretic mobilities of particles in concentrated suspensions has been developed. The usual techniques for the study of electrophoretic mobility, such as the microelectrophoretic method and the moving-boundary method, arc in general not applicable to suspensions more concentrated than about 1 % by volume of dispersed phase, nor are they readily applied to suspensions of particles having an appreciable sedimentation velocity. The new apparatus, which employs an improved design of mass-transport cell, has been used to study suspensions containing up to 50% by volume of dispersed phase. Gravitational effects are eliminated by continuous rotation of the cell during a mobility determination.

Data on kaolin—water systems are presented to illustrate the experimental technique and precision of the measurements. These data are also used to show the relation between the salt flocculation value of a suspension and its electrophoretic mobility.
Clay Mineral Formation in Mud Pots, Yellowstone Park, Wyoming
Authors: Droste John B.
Published: August 2006

Kaolinitic, montmorillonitic, illitic, and mixed-layer clay minerals are found in mud springs and mud pots of Yellowstone Park. A sequence of alteration is proposed as Phase I, alteration of bedrock and sediments by hot spring waters to produce three-layer clay minerals (including mixed layer species) and kaolinite-group minerals; Phase II, further alteration to produce a mud composed predominantly of kaolinite and some form of silica.
Polyelectrolyte Reinforced Aerogels of Clays—Application as Chromatographic Adsorbents
Authors: van Olphen H.
Published: August 2006

Aerogels of clays can be prepared by freeze-drying of clay water gels. The mechanical strength of the aerogels is improved by the addition of water-soluble polyelectrolytes to the hydrogels.

The porosity of the powdered aerogels can be adapted to the requirements for adsorbents in gas chromatography by compounding the hydrogels with suitable amounts of polyelectrolytes. Simultaneously, the surface of the clay may be modified by adsorption of polar or cationic organic compounds in order to achieve specific chromatographic separations.

Because of the toughness of the clay-polyelectrolyte aerogels, they can be rolled out to thin sheets which may be applied as chromatographic papers.
Clay Mineral Nomenclature
Authors: Brindley G. W.
Published: August 2006

Discussions and recommendations of The Clay Mineral Society, Nomenclature Committee, 1965-6, are summarized.
Hydroxy Interlayers in Expansible Layer Silicates
Authors: Rich C. I.
Published: August 2006

Vermiculites and smectites in soils and sediments are frequently partially interlayered or “chloritized”. Dioctahedral expansible layer silicates are those most frequently interlayered, and hydroxy-Al appears to be the principal component of the non-exchangeable interlayer material.

The most favorable soil conditions for interlayer formation appear to be: moderate pH (4·6–5·8), frequent wetting and drying cycles, and low organic matter content.

In marine sediments, hydroxy-Mg interlayering may be significant. Soil-derived clays containing partially filled hydroxy-Al “brucite” sheets may be filled out with hydroxy-Mg. Under reducing conditions, hydroxy-Fe interlayers may be important.

Depending on the OH/Al ratio and Al content of hydroxy-Al interlayers, expansible layer silicate may either promote or retard the formation of gibbsite. Interlayered expansible layer silicates also may be precursors to kaolinite.
Dickite and Kaolinite in Pennsylvanian Limestones of Southeastern Kansas
Authors: Schroeder Richard J. , Hayes John B.
Published: August 2006

Dickite and kaolinite are polymorphs of Al4(Si4O10)(OH)8. Dickite traditionally is regarded as hydrothermal, based on field and laboratory evidence. Dickite and kaolinite occur in cavities in phylloid algal limestones, in interstices of biocalcarenites and sandstones, and along joints, fractures, and stylolites, in Pennsylvanian rocks exposed throughout 9600 square miles of southeastern Kansas. The stratigraphic interval of approximately 1100 ft extends from the Fort Scott Limestone (Desmoinesian) through the Lecompton Limestone (Virgilian). The best crystallized dickites are found in porous algal limestones as pockets of glistening white powder composed of well developed pseudohexagonal plates up to 40 μ across. Very well crystallized kaolinites occur similarly, except the crystals are much smaller. Less well crystallized dickites and b-axis disordered kaolinites occur in less porous rocks. Variations in crystal size and morphological development are genetically significant.

Dickite-kaolinite distribution is related to: (1) stratigraphic alternation of limestones and impervious shales; (2) gentle, westward regional dip; (3) thick, mound-like buildups of highly porous algal limestones, miles in length and width; (4) igneous intrusions (early Tertiary?) in Woodson and Wilson counties. Dickite is confined to an elliptical area 125 miles long northeast-southwest, extending 60 miles eastward from the intrusions. Dickite is associated preferentially with porous algal mounds. Kaolinite occurs in less porous rocks within the dickite area, and also is abundant well beyond. Heated groundwaters, possibly mixed with magmatic waters, moved readily up-dip and along strike outward from the intrusions through the conduit-like algal mounds; dickite was deposited from such solutions. Where water movement was restricted or where water had travelled tens of miles from the intrusions, water temperature fell below the limit for dickite crystallization, and kaolinite precipitated instead. Kansas dickite, unlike most other reported dickites, formed in rocks that were neither deeply buried nor extensively altered hydrothermally.
Infrared Study of the Orientation of Chlorobenzene Sorbed on Pyridinium-Montmorillonite
Authors: Serratosa J. M.
Published: August 2006

The pyridinium-montmorillonite complex has the ability to sorb additional aromatic molecules between the layers. The neutral molecules occupy the vacant space produced by the change in orientation of the pyridinium ion from a parallel to a perpendicular position and with the N-H group directed toward the negative unit layer surface.

In favorable cases the orientation of the additional neutral molecules can be ascertained by infrared spectroscopy. Examples of this analysis are presented in the complexes of pyridinium-montmorillonite with chlorobenzene. The molecules adopt a vertical orientation but with the halogen bond axes parallel to the layers.
Cationic Diffusion in Clay Minerals: II. Orientation Effects
Authors: Lai T. M. , Mortland M. M.
Published: August 2006

The effect of orientation of vermiculite particles on the diffusion of Na ion was measured by a tracer technique. The diffusion measurements were made on pellets prepared by pressing freezedried vermiculite in a cylindrical die and the diffusion coefficient evaluated by a thin-film boundary condition of Fick’s law. Because flakes of vermiculite were highly oriented under the pressing force, it was possible to prepare different angles of specimen orientation with respect to the surface where diffusion was initiated. Mathematical relationships of orientation angle, axial ratio of the platelets, and apparent diffusion coefficient were developed. The experimental results on the diffusion of Na ion in K-vermiculite of clay size gave apparent diffusion coefficients of 2·21 × 107cm2 sec−1 when the diffusion flux was parallel with the clay platelets and 0·45 × 10−7 cm2 sec “1 when the flux was perpendicular to the clay platelets. For the diffusion of Na ion into Na-vermiculite, apparent diffusion coefficients were obtained of 1·18 × 10−8cm2sec−1 when the diffusion flux was parallel with the clay platelets, and 0·18 × 10−8 cm2 sec−1 when the flux was perpendicular to the platelets. For K-vermiculite, the change in apparent diffusion coefficient is a simple one of particle geometry. The Na-vermiculite system exhibited more complicated behavior.
Aluminum Interlayers in Layer Silicates Effect of OH/Al Ratio of Al Solution, Time of Reaction, and Type of Structure
Authors: Sawhney B. L.
Published: August 2006

Aluminum interlayers were synthesized under the same experimental conditions in a number of vermiculites and montmorillonites from different sources to determine the effects of the degree of neutralization of Al solutions, the time of reaction, and the type of structure.

Vermiculite fixed Al as well as hydroxy-Al ions in its interlayers, producing a stable 14 Å spacing and decreasing its cation exchange capacity considerably. Heating the Al-interlayered vermiculite at 300°C produced an interstratified mixture, indicating that some interlayers collapsed while others did not. The different collapse was attributed to different charge on vermiculite layers.

Neither the aging of vermiculite in Al solutions nor their OH/A1 ratios changed the stability of the interlayers appreciably.

Montmorillonites, on the other hand, did not fix Al ions but fixed appreciable amounts of hydroxy-Al ions. In addition, the stability of the interlayers in montmorillonite increased on aging in hydroxy-Al solutions and exceeded the stability of the interlayers produced in vermiculite. To explain the greater stability of montmorillonite interlayers, it was postulated that the more expanded interlayer space in montmorillonite provides a favorable locale for the organization of hydroxy-Al ions into gibbsite structure while the restricted expansion in vermiculite prevents it.
Retention of Crude Oil Bases by Clay-Containing Sandstone
Authors: Reed M. G.
Published: August 2006

Retention of basic components of a crude oil by clay-containing reservoir sandstone was studied by flowing crude oil through cores and monitoring the concentration of bases in the effluent. Cores that were H-saturated, H-saturated then aged, and Na-saturated retained 0·82, 0·82, 0·70, and 0·20 meq base/100 g, respectively. Barium exchange capacity values were 0·86, 0·71, and 0·83 meq/100 g. Subsequent floods with water, toluene, and chloroform-acetone removed oil that had increasing concentrations of base and N, indicating that the basic fraction of crude oil was the most difficult fraction to extract from clay mineral surfaces. Retained bases were nitrogenous and the most tenaciously held bases had base/N ratios approaching unity.
Electron Microprobe Study of Kaolin
Authors: Weaver Charles E.
Published: August 2006

Electron microprobe studies of kaolinite indicate that most of the Fe is evenly distributed throughout the kaolinite and must either be in the structure or occur as very small particles adsorbed on the surface. In addition to Ti the anatase impurities contain Fe and Mg. Fe, Mg, Mn, V, and K are present in biotite. It is necessary to concentrate the fine-grained mineral impurities in order to study them with the electron microprobe.
Absorption of Pyrimidines, Purines, and Nucleosides by Co-, Ni-, Cu-, and Fe(III)-Montmorillonite (Clay-Organic Studies XIII)
Authors: Lailach G. E. , Thompson T. D. , Brindley G. W.
Published: August 2006

Absorptions of purine and pyrimidine derivatives by Co- and Ni- montmorillonite at pH < 6 and by Cu-montmorillonite at pH < 3 are similar to their absorption by Ca-montmorillonite and take place primarily by a cation exchange process. In the weakly acidic to weakly alkaline range, absorption is due to complex formation with the inorganic cations, and decrease in the order Cu ≫ Ni > Co ≫ Ca. Adenine, 7-methyladenine, hypoxanthine, and purine are strongly absorbed, 9-methyladenine, 6-chloropurine, and cytosine are weakly absorbed, and thymine and uracil are not absorbed. At pH < 5, the nucleosides are absorbed by Co-, Ni-, and Cu-montmorillonite in approximately the same manner as by Ca-montmorillonite, but at pH > 6 their absorptions decrease in the order Cu ≫ Ni > Co > Ca. Fe(III)-montmorillonite behaves quite differently from the other mont-morillonites studied. With purines and pyrimidines, there is strong absorption from pH 3 to pH 7–8; with the nucleosides, the absorption varies considerably with the compounds considered decreasing in the order adenosine > cytidine ≫ guanosine ≫ inosine.
Heterogeneity of Montmorillonite Surface and Its Effect on the Nature of Hydroxy-Aluminum Interlayers
Authors: Hsu Pa Ho
Published: August 2006

A specimen montmorillonite (Arizona bentonite) was treated with hydroxy-aluminum solutions of various basicity. The cation exchange sites of this clay were found not to be homogeneous in their strength of retaining hydroxy-aluminum polymers; this strength varied from very weak, with which the Al polymers were only loosely held, to very strong, with which stable interlayer Al-clay complexes were formed. When a large amount of clay was treated with a small amount of solution, the polymers were held only in positions of strong affinity; the polymers were difficult to extract with neutral salt solutions and did not change to crystalline Al(OH)3 during prolonged aging. When a small amount of clay was treated with a large amount of solution, the exchange sites were completely occupied by polymers; a portion of these polymers was easily extractable with neutral salt solutions and, during aging, changed to Al(OH)3. This contrast is significant in any attempt to compare results obtained under different experimental conditions and to correlate laboratory experimentation with the occurrence of gibbsite and interlayer Al-clay complexes in nature.
Quantitative Analysis of Naturally Occurring Multicomponent Mineral Systems by X-Ray Diffraction
Authors: Moore Charles A.
Published: August 2006

A theory for the quantitative analysis of multicomponent mineral systems by means of X-ray diffraction is presented. A linear interaction between mineral pairs is postulated. The theory is verified experimentally for bicomponent and tricomponent systems using a variety of sample preparation techniques including random powder mounts, suspensions sedimented onto glass slides, and pressed powder pellets. The minerals studied include quartz, fluorite, kaolinite, glauconite, illite, and montmorillonite.

The determination of the linear interaction factors for mineral pairs is treated theoretically and experimentally. Emphasis is placed upon techniques that are applicable to naturally occurring mineral systems. Four approaches are presented for determining linear interaction coefficients for various types of such mineral systems. These approaches are applied to the experimental data and the results are compared. Results accurate within 2 per cent are commonly obtained.

Experimental techniques are discussed and a qualitative and quantitative error analysis is presented. It is shown that the indicated quantities present may not be particularly sensitive to the value of the linear interaction coefficient.
Analysis Of Iron In Layer Silicates By Mossbauer Spectroscopy
Authors: Taylor G. L. , Ruotsala A. P. , Keeling R. O.
Published: August 2006

Analysis of Mossbauer effect in layer silicates provides a spectroscopic method for determining valences and coordination of iron. In this study Mossbauer spectra were obtained for amesite, cronstedtite, nontronite, two glauconites, biotite, lepidomelane, chlorite, minnesotaite, vermiculite. stilpnomelane, and chloritoid.

Trivalent iron was detected in tetrahedral coordination. Abundant trivalent iron in octahedral coordination apparently causes quadrupole splitting values of divalent iron in the same mineral to decrease. This phenomenon was noted in cronstedtite and glauconite. In cases where divalent iron predominates in the mineral, the quadrupole splitting is larger. It is generally accepted that ferrous iron is largely in octahedral coordination. This suggests that the octahedral sites may be more distorted when ferric iron is present in the octahedral sheet. In biotite, quadrupole splitting of divalent iron is decreased when trivalent iron is present in tetrahedral sheets. This suggests that there is also more distortion in the octahedral sheet because of iron in tetrahedral positions.
Sealing Properties of Bentonite Suspensions
Authors: Rollins M. B.
Published: August 2006

Sealing with waterborne clays is a rapid and low cost method of controlling seepage through porous media whenever the clay source is within economical shipping distance of the sealing site. But more must be learned about this method of sealing before it can be fully utilized.

Water impedance of waterborne bentonites, as measured by water loss in the filter press test, was correlated with their physical, chemical and mineralogical properties. A multiple linear regression analysis showed clay content and exchangeable sodium percentage (ESP) were most highly correlated with water impedance. Swelling, viscosity and gelation of these clays play only a secondary role in forming a water barrier when used as dilute waterborne sealants as suggested by these and other data.

There were strong positive correlations between water loss and samples high in silt-sized cristobalite, quartz and feldspar; and negative correlations between water loss and samples high in clay-sized montmorillonite, chlorite and illite.

Predicted minimum clay contents (of prospective sealers) were found to be 65–75 per cent clay at 70 and 20 per cent exchangeable sodium, respectively.
The Nature of Anauxite
Authors: Langston Robert B. , Pask Joseph A.
Published: August 2006

Anauxite crystals are reported to contain a higher SiO2:Al2O3 ratio than the 2:1 ratio found in kaolinite. A structure proposed for anauxite places the excess silica in double silica sheets, but an exact structure for anauxite has never specifically been determined. Many workers believe that anauxite is kaolinite associated with some extremely fine-grained excess silica which is not a part of the structure. Eight specimens studied in this work included portions of type materials from Bilin, Czechoslovakia, and the lone formation in California.

Amorphous silica and alumina are readily soluble in boiling (N/2)NaOH. Kaolinite is only slowly soluble in this reagent, but becomes readily soluble after dehydroxylation. Weight loss, differential solution rate, kinetic and X-ray diffraction studies were used to establish that the kaolinite clay fraction in the anauxite specimens had the composition of:

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Some of the anauxite grains are single crystals, while others are aggregates. The latter appear to be bound together by an amorphous silica phase. Hot caustic leaching extracts the amorphous silica and breaks up the aggregates producing “fines.” Improved characterizations of minor impurities were obtained when the residues from hot caustic treatments were studied with X-ray diffraction techniques.
Hydrothermal Argillation of Volcanic Pipes in Limestone in Mexico
Authors: Keller W. D. , Hanson Robert F.
Published: August 2006

Previously reported deposits of kaolin of hydrothermal origin in Mexico have been described from igneous parent rocks dominantly extrusive in occurrence. Recently observed evidence from other localities confirms an intrusive mode of occurrence, however, for hydrothermally kaolinized agglomerate and tuff within limestone host rock. Three such occurrences have been recognized near Jasso-Calera, north of Mexico City, and near Coacoyula, Guerrero, and Sombrerete, Zacatecas.

The contacts of these clay deposits with limestone show regularly a concentration of iron-rich minerals such as red to brown oxides and/or nontronite, but less commonly an irregular development of grossularite, and bands or pockets of endellite. Silica gossans indicate that hypogene altering solutions were active into the current geomorphic cycle. Kaolinite at the center of the clay body and endellite at the border zones are interpreted as originating, respectively, from in situ alteration of solid rock and deposition from ambient solutions.
Determination of Surface Area by Surfactant Adsorption in Aqueous Suspension — I. Dodecylamine Hydrochloride
Authors: Kalb G. William , Curry R. Bruce
Published: August 2006

Conductometric titrations of clay suspensions with surfactant solutions offer a rapid method of surface area determination of clay particles suspended in aqueous media. A cationic surfactant, dodecylamine hydrochloride, was used in this investigation. This surfactant was adsorbed by electrostatic bonding at cation exchange sites and by van der Waals forces. A monomolecular or bimolecular layer of the surfactant coats the particle and the completion of the layer is determined from a change in slope of the conductometric titration curve due to the formation of micelles. Good agreement between this method and BET determined values were obtained for kaolinite. The bentonite suspensions had a strong tendency to flocculate after the initial stage of adsorption causing the results to vary considerably. This method of surface area measurement of clay particles offers many advantages over the present techniques: (1) a dry particle is not required; (2) the equipment is inexpensive and available in many laboratories; (3) the method is rapid; (4) vacuum and high temperature are not required, and (5) the method measures the internal as well as external surface area.
Hydraulic and Electrical Flows in Clays
Authors: Arulanandan Kandiah
Published: August 2006

The electrical conductivity of saturated kaolinite clay-water-electrolyte systems of different particle size distributions and of illite and montmorillonite clays were determined over the frequency range of 50–108 c/s. The conductivity increases as the frequency increases, and the experimental values show two distinct dispersions, one in the low frequency range and the other in the high frequency range. The frequency range over which the first dispersion occurs is experimentally shown to be dependent on particle size. The average particle size is uniquely related to the frequency at which half the dispersion occurs. The magnitude of conductivity variation, the high frequency conductivity and the streaming potential values are related to the microscopic permeability coefficient. This microscopic permeability coefficient, evaluated from a knowledge of the above electrical properties, is shown to be uniquely related to the Darcy permeability coefficient at various consolidation states of the kaolinite clays. Similar unique relationships have been observed in illitic clays.