bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of new seismic attributes to collapse chimneys in the Fort Worth Basin
Authors: Sullivan E. Charlotte , Marfurt Kurt J. , Lacazette Alfred , Ammerman Mike
Published: August 2006

Three-dimensional seismic volumes from the central Fort Worth Basin display roughly circular collapse chimneys that extend vertically about [Formula: see text] from the Ordovician Ellenburger Formation to the Atokan (middle Pennsylvanian) Caddo Limestone. Collapse chimneys in carbonates may be caused by subaerial karst, hydrothermal, or tectonic extensional processes. We use 3D multitrace geometric attributes including coherence, volumetric curvature, and energy-weighted, coherent amplitude gradients to investigate details of the origin of these structures. The Ordovician Ellenburger surface resembles a subaerial karst landscape of cockpits, dolines, and frying-pan valleys, while resistivity-based wireline image logs record [Formula: see text] of karst breccia facies. However, images from coherence and long-wavelength most-positive and most-negative-curvature volumes show many of the [Formula: see text] collapse features are associated with basement faults or with subtle Pennsylvanian and younger tectonic features, rather than with intra-Ellenburger collapse. We hypothesize that although the Ellenburger surface does contain a subaerial karst overprint, the first-order control on the formation of the vertically extensive collapse chimneys is bottoms-up tectonic-induced extensional collapse. Although these collapse chimneys have been affected by burial fluid diagenesis, the main consequence of burial fluid flow may be limited to the documented cementation of macrofractures. The apparent dominance of tectonic extension processes over subaerial karst and hydrothermal processes has basinwide implications for distribution of fractures, late-stage cements, and reservoir development and compartmentalization.
Seismic processing in the inverse data space
Authors: Berkhout A. J.
Published: August 2006

Until now, seismic processing has been carried out by applying inverse filters in the forward data space. Because the acquired data of a seismic survey is always discrete, seismic measurements in the forward data space can be arranged conveniently in a data matrix [Formula: see text]. Each column in the data matrix represents one shot record. If we represent seismic data in the temporal frequency domain, then each matrix element consists of a complex-valued number. Considering the dominant role of multiple scattering in seismic data, it is proposed to replace data matrix [Formula: see text] by its inverse [Formula: see text] before starting seismic processing. Making use of the feedback model for seismic data, multiple scattered energy is mapped onto the zero time axis of the inverse data space. The practical consequence of this remarkable property may be significant: multiple elimination in the inverse data space simplifies to removing data at zero time only. Moving to the inverse data space may cause a fundamental change in the way we preprocess and image seismic data.
Multicenter Phase II Clinical Study of Iodine-131–Rituximab Radioimmunotherapy in Relapsed or Refractory Indolent Non-Hodgkin’s Lymphoma
Authors: Leahy Michael F. , Seymour John F. , Hicks Rodney J. , Turner J. Harvey
Published: August 2006

Purpose

To evaluate efficacy and safety of iodine-131 (131I) –rituximab chimeric anti-CD20 antibody radioimmunotherapy in patients with relapsed or refractory indolent non-Hodgkin's lymphoma (NHL).

Patients and Methods

After a standard loading dose of rituximab 375 mg/m2, individualized dosimetry was performed by whole-body gamma imaging of a tracer activity of 131I-rituximab followed by administration of a therapeutic activity of 131I-rituximab to deliver an estimated whole-body radiation absorbed dose of 0.75 Gy.

Results

Ninety-one patients were entered onto the trial: 78 patients (86%) had follicular lymphoma, six patients (7%) had mucosa-associated lymphoid tissue/marginal zone lymphoma, and seven patients (8%) had small lymphocytic lymphoma. The objective overall response rate (ORR) was 76%, with 53% attaining a complete response (CR) or CR unconfirmed (CRu). Median duration of response for patients achieving CR/CRu was 20 v 7 months for those with a partial response (P = .0121). Median progression-free survival for the entire cohort was 13 months, with 14% remaining relapse free beyond 4 years. Median follow-up was 23 months, with a 4-year actuarial survival rate of 59% ± 10%. Toxicity was principally hematologic; grade 4 thrombocytopenia occurred in 4% and neutropenia occurred in 16% of patients, with nadirs at 6 to 7 weeks after treatment.

Conclusion

131I-rituximab radioimmunotherapy of relapsed or refractory indolent NHL achieves high ORR and CR rates with minimal toxicity.
An Easy Approach to Fabrication of Silica Nanofibers/Nanotubes via Wrapping Sacrificial Cd(OH)2 Nanostrands
Authors: He Junhui , Li Chengzhang
Published: August 2006

An easy approach to synthesis of silica nanofibers and nanotubes via wrapping sacrificial Cd(OH)2 nanostrands was developed, and a plausible formation mechanism was proposed.
Direct α-Hydroxylation of Ketones Catalyzed by Organic–Inorganic Hybrid Polymer
Authors: Arai Takayoshi , Sato Toru , Noguchi Hiroshi , Kanoh Hirofumi , Kaneko Katsumi , Yanagisawa Akira
Published: August 2006

Direct α-hydroxylation of ketones using molecular oxygen was accomplished by organic–inorganic hybrid polymers. A newly prepared Cu-piperazine hybrid polymer was tolerant to the basic conditions, and with employment of lithium hydroxide smoothly catalyzed the α-hydroxylation of ketones. In the present catalytic process not only tetralone derivatives, but also acyclic ketones were converted to the α-hydroxy ketones in good yield.
Extending the Bounds of Rationality: Evidence and Theories of Preferential Choice
Authors: Rieskamp Jörg , Busemeyer Jerome R , Mellers Barbara A
Published: August 2006

Most economists define rationality in terms of consistency principles. These principles place “bounds” on rationality—bounds that range from perfect consistency to weak stochastic transitivity. Several decades of research on preferential choice has demonstrated how and when people violate these bounds. Many of these violations are interconnected and reflect systematic behavioral principles. We discuss the robustness of the violations and review the theories that are able to predict them. We further discuss the adaptive functions of the violations. From this perspective, choices do more than reveal preferences; they also reflect subtle, yet often quite reasonable, dependencies on the environment.
Advancing Beyond Advances in Behavioral Economics
Authors: Fudenberg Drew
Published: August 2006

This essay discusses the field of behavioral economics, with a focus on the papers in Advances in Behavioral Economics. These papers show that there is a body of “behavioral facts” that is both economically significant and regular enough to be modeled. For the field to advance further, it should devote more attention to the foundations of its models, and develop unified explanations for a wider range of phenomena.
The Multilevel Capacitated Minimum Spanning Tree Problem
Authors: Gamvros Ioannis , Golden Bruce , Raghavan S.
Published: August 2006

In this paper, we consider the multilevel capacitated minimum spanning tree (MLCMST) problem, a generalization of the well-known capacitated minimum spanning tree (CMST) problem, that allows for multiple facility types in the design of the network. We develop two flow-based mixed integer programming formulations that can be used to find tight lower bounds for MLCMST problems with up to 150 nodes. We also develop several heuristic procedures for the MLCMST problem. First, we present a savings-based heuristic. Next, we develop local search algorithms that use exponential size, node-based, cyclic and path exchange neighborhoods. Finally, we develop a hybrid genetic algorithm for the MLCMST. Extensive computational results on a large set of test problems indicate that the genetic algorithm is robust and, among the heuristics, generates the best solutions. They are typically 6.09% from the lower bound and 0.25% from the optimal solution value.
Recurrent Neural Networks for Music Computation
Authors: Franklin Judy A.
Published: August 2006

Some researchers in the computational sciences have considered music computation, including music reproduction and generation, as a dynamic system, i.e., a feedback process. The key element is that the state of the musical system depends on a history of past states. Recurrent (neural) networks have been deployed as models for learning musical processes. We first present a tutorial discussion of recurrent networks, covering those that have been used for music learning. Following this, we examine a thread of development of these recurrent networks for music computation that shows how more intricate music has been learned as the state of the art in recurrent networks improves. We present our findings that show that a long short-term memory recurrent network, with new representations that include music knowledge, can learn musical tasks, and can learn to reproduce long songs. Then, given a reharmonization of the chordal structure, it can generate an improvisation.
Dye Adsorption as a Method of Identifying Clays
Authors: Dodd Charles G.
Published: August 2006

Dyestuffs and other reagents which exhibit characteristic colors when
adsorbed on clay granules frequently have been employed as aids in clay
identification. The colors generally are believed to result from pleochroic
effects and acid-base or oxidation-reduction reaction mechanisms. Certain
aniline dyes, solutions of which vary in color according to their hydrogen
ion content, may be used to indicate the relative acidity of clay.surfaces
as well as to heighten the natural pleochroism of kaolin minerals. When n
clay sample has been pretreated with acid, the colors assumed by the
adsorbed dye depend on the characteristic base exchange capacities of the
various clay mineral groups present.

Aromatic diamines, amino phenols, and other compounds which can be
oxidized to colored semiquinone cations permit particularly sensitive and
positive identification of members of the montmorillonoid family and certain
other three-layer clay minerals. Theories concerning the nature of this
apparently catalytic oxidation on clay surfaces are inadequate to explain
the reactions. New concepts and additional experimental information are
needed.
Identification of Clay Minerals by X-Ray Diffraction Analysis
Authors: Brindley George W.
Published: August 2006

Since X-ray diffraction patterns are directly related to crystal
structures. X-ray identification is, in principal, better suited to the
recognition of structural groups and structural varieties than of chemical
species.

Well-formed kaolin, mica, and chlorite structures give rise to
characteristic 7, 10 and 14Å spacings which are relatively easily
identified. Hydrated forms, such as hydrated halloysite
(d = 14Å) and montmorillonoids under normal
conditions (d= 14Å), are recognized either by
low-temperature dehydration giving characteristically diminished spacings,
or by the formation of organic complexes giving characteristically increased
spacings. This introduces at once the principle that X-ray identification
may, and generally does, entail the study of mineral modification by
suitable chemical and/or thermal treatment.

The main requirements in the X-ray technique are: (1) Ability to record
long spacings up to 2.5Å or even higher values; (2) well focused lines with
good resolution; (o) absence of background scattering and white radiation
anomalies. Of these, (1) and C) lie within the control of the investigator,
but (2) depends partly on the material.

The main difficulties of X-ray identification are: (1) The multiplicity
of lines when many components are present, and (2) poorly defined diagrams
arising from poor crystallinity and/or small size of crystals. The first can
be treated experimentally, but the second is inherent in the problem.
Simidification of X-ray diagrams is possible by sedimentation, acid
treatment and thermal treatment and by the use of orientated.specimens. Poor
quality powder diagrams (if not due to poor technique) are of interest in
themselves and may still give valuable information concerning the clay
minerals, more particularly when monomineralic or mainly monomineralic
fractions are used. Line profiles give valuable indications of randomly
displaced layers and of interstratified sequences.

The recognition of chemical species by X-rays is difficult but some
progress can be made if pure or nearly pure specimens are obtainable. The
recognition of di- and tri-octahedral minerals by the (060) spacing is well
known but the recognition of micas and chlorites in any greater detail is
difficult. A consideration of basal spacings and basal intensities may make
more specific identification possible.
Clay Technology in Ceramics
Authors: Henry Edward C.
Published: August 2006

Clays are used in the ceramics industries largely because of their
contribution to the moulding and drying properties of the wares being
produced; many clays, such as the flint clays, are used because of favorable
behavior during firing or because they produce favorable properties in fired
ware.

To assure the most effective use of a clay, the ceramic technologist
must meet problems of purification, aging, bacterial action, and the
improvement of the working properties of clays and bodies through additions
of non-plastic materials or chemicals. He deals with flocculation and
deflocculation, thixotropy, and related phenomena in casting slips. Control
of drying behavior is important. Finally, the ceramist is concerned with the
influence of the clay content of ceramic bodies on their behavior during
firing.
Clay Mineral Investigation of Sediments in the Northern Gulf of Mexico
Authors: Grim Ralph E. , Joitns William D.
Published: August 2006

Clay mineral studies of recent sediments from a diversity of environments in the vicinity of Rockport, Texas, have been made as part of American Petroleum Institute Project 51.

The bulk of the argillaceous material in these sediments is a complex mixture of poorly crystallized three-layer clay minerals. Problems of the identification and nomenclature of the components of such mixtures are considered.

Variations in areal distribution of the clay mineral constituents indicate progressive diagenesis in response to changing chemical environment. The gradual loss of montmorillonitic source material with the ultimate formation of poorly crystalline illitic and chloritic phases has been related to variations in environment. Environmental criteria based on clay mineral compositions are suggested.
Clay Mineral Content of Gulf Coast Outcrop Samples
Authors: Simons L. H. , Taggart M. S.
Published: August 2006

Clay samples were taken from formations outcropping between Corpus Christi and Uvalde, Texas, during the annual field trip of the Corpus Christi Geological Society in 1953. The geologic age of the formations sampled ranges from Quaternary to Upper Cretaceous. Both surface and near-surface samples were taken. The results of examination of these samples by use of x-ray diffraction and electron microscope techniques indicate marked differences in the relative proportions of montmorillonite, kaolinite, and illite. Comparison of surface and near-surface samples indicates the probable course of weathering.
The Solubility of Silica in Hydrogen Beidellite
Authors: Woodruff C. M.
Published: August 2006

Electrodialyzed suspensions of clay minerals are viewed generally as insoluble silicates in which the exchange complex is saturated with hydrogen. An investigation of the relative activities of different exchangeable ions on beidellite clay brought to light the fact that a freshly prepared hydrogen clay containing a trace of the non-adsorbed chloride ion, when filtered, yielded a solution containing the chloride ion in association with silica rather than with hydrogen.

The filtrate from the freshly prepared suspension was clear and had a pH value of 5.5. After standing 24 hours the filtrate became cloudy and the pH value dropped to 3.5 corresponding to the concentration of acid produced by the chlorides in association with hydrogen. Analysis of the clear filtrate revealed that the chlorides were associated with silica. The amount of soluble silica in the filtrate from the clay suspension was related directly to the amount of exchangeable hydrogen in the clay. No soluble silica was present in the filtrate from clay which had been neutralized with either potassium or calcium hydroxide.
An American Occurrence of Volkonskoite
Authors: McConnell Duncan
Published: August 2006

Chromium-bearing members of the montmorillonite group have been reported heretofore only for Russian localities, where they have been related genetically to serpentines. A green mineral which occurs in high-angle fissures in the Morrison formation (Upper Jurassic) near Thompsons, Utah, contains about 2 percent Cr2O3. Data were obtained by optical and electron microscopy, x-ray powder diffraction, and gravimetric and spectroscopic chemical methods. The ultimate source of the chromium remains an unresolved geochemical question, as do the sources of vanadium and uranium in the Morrison sandstone.
Distribution of Clay Minerals and Ion-Exchange Capacity in Some Sedimentary Materials
Authors: Hathaway John C. , Carroll Dorothy
Published: August 2006

The cation-exchange capacity of the clay fraction was determined in 67 samples of various types of sedimentary materials, and the clay minerals were identified from x-ray diffractometer patterns of oriented aggregates. The probable quantitative clay mineral composition was established for each sample assuming a comparable degree of crystallinity for the clay minerals in the sample. Agreement was poor between the ion-exchange capacities determined and those predicted from the clay mineral composition. The results suggest that the figure obtained for the ion-exchange capacity of a sample of sedimentary material may be misleading as a guide to the types of clay minerals present.

The residual soils among the sedimentary materials examined had clay fractions with greater variation in ion-exchange capacity than did unconsolidated sediments generally of alluvial origin.
Thermogravimetric Analysis of Clay and Clay-Like Minerals
Authors: Mielenz Richard C. , Schieltz N. Cyril , King Myrle E.
Published: August 2006

The thermogravimetric method offers a new approach to the study of clay and clay-like minerals as well as other minerals and compounds that gain or lose weight upon heating. This method is complementary to differential thermal analysis, which records energy gains or losses upon heating. Thermogravimetric curves for clay and clay-like minerals are presented and correlated with curves obtained by the differential thermal method. The apparatus, procedures, limitations, and application of the method are described and illustrated.
Multifunctional Ionization as Illustrated by the Clay Minerals
Authors: Marshall C. E.
Published: August 2006

The electrochemical properties of clays are discussed under four rules which arise from considerations of the bonding energy of ions associated with charged surfaces. The mean free bonding energy of a cation associated with a negatively charged surface is determined by calculation from conventional potentiometric measurements with membrane electrodes.

The first three rules are concerned with the effects of valency upon ionization. They arise directly from the method of calculating cationic mean free bonding energies, applicable to monofunctional surfaces as regards Rule 3, and to polyfunctional surfaces also as regards Rules 1 and 2.

The fourth rule (Jarusov’s rule) deals with mixtures of cations on polyfunctional surfaces. It may be expressed verbally by stating that the cation with the higher mean free bonding energy preempts those positions on the surface which manifest greater mean free bonding energy.

The incidence of each rule is examined, using data from studies of cationic activities in clay systems. The factors which cause deviations from these idealized rules are discussed. Graphical data are presented for Wyoming bentonite, Arizona bentonite (montmorillonite), and Putnam clay (montmorillonite group); illite, kaolinite and attapulgite.
Chemical Determination of Tetrahedral Ions in Nontronite and Montmorillonite
Authors: Osthaus B. B.
Published: August 2006

Samples of nontronite and montmorillonite were digested with dilute hydrochloric acid for various periods of time. Chemical determinations of the acid-soluble ions were made for each period of digestion. Curves are presented showing the rates of solution of these minerals as decreasing exponential functions of time. A change in the slopes of the curves, as plotted on semilogarithmic paper against time on the linear scale, suggests different rates of solution for the ions in the tetrahedral and octahedral layers. The initial slope of the curves represents the simultaneous rates of solution of the octahedral and tetrahedral layers with the octahedral layer predominating. The second slope of the curves represents the rate of solution of the tetrahedral layer predominantly. Extrapolation of this slope to zero time is thought to give the percent of the tetrahedrally substituted ions within very close limits. Solubility curves of nontronite suggest the presence of both iron and aluminum in the tetrahedral layer. The solubility curves for Polkville montmorillonite indicate there is no substitution for silicon in the tetrahedral layer. Experimental values of tetrahedral substitution in nontronite check very closely with values postulated from the theoretical calculations obtained from the chemical analysis of the mineral.
Electron Microscopy of Clay Surfaces
Authors: Bates Thomas F. , Comer J. J.
Published: August 2006

Improvements in replica techniques have made possible the high magnification study of textural characteristics and surface features of clay aggregrates found either in nature or in the laboratory. The most successful method of sample preparation involves pre-shadowing the specimen with platinum and backing this with a layer of carbon prior to removal of the clay with a suitable solvent.

Data on orientation and packing of clay particles are readily obtained. The method is useful to investigate clays in which the characteristic morphology is easily affected by environmental conditions or by sample preparation for other methods of study.

Replicas of kaolinite indicate that many of the pseudohexagonal plates seen in electron micrographs are cleavage fragments. Investigations of halloysite (4 H2O) using this technique prove that the tubes exist as such in the bulk clay. Striations on montmorillonite flakes that intersect at an angle of sixty degrees suggest a degree of morphological crystallinity that is apparently destroyed when the material is dispersed prior to study in the electron microscope. Replicas of dickite, attapulgite and weathered feldspar also show features that have not heretofore been seen in electron micrographs.
Structural Irregularities in Hydrous Magnesium Silicates
Authors: Bradley W. F.
Published: August 2006

The crystal structures of chrysotile, antigorite, attapulgite, sepiolite, vermiculite, and montmorillonite are discussed in the light of the degree to which they resemble chlorite.

The proposal is advanced that the perfection of articulation between tetrahedrally and octahedrally coordinated layers is temperature-sensitive, and that the several crystallizations reflect the degree to which difficulty of articulation limits the growth of particular compositions.
DTA of Kaolinite and Montmorillonite Under Water Vapor Pressures up to Six Atmospheres
Authors: Stone Robert L. , Rowland Richards A.
Published: August 2006

Thermograms of kaolinite and montmorillonite were obtained at water-vapor pressures varying from approximately 0.0001 to 4,500 mm. of Hg with a variable pressure, dynamic gas, differential thermal analysis apparatus. The beginning of the kaolinite endotherm is shifted to a higher temperature with increasing water-vapor pressure. The sharp kaolinite exotherm is shifted to a lower temperature until at six atmospheres water-vapor pressure it makes a small broad peak at approximately 900° C. The dehydroxylation endotherm of montmorillonite is almost unaffected. The 900° C endotherm and the recrystallization exotherm are shifted to a lower temperature with increasing water-vapor pressure. The temperatures of the start of the endothermic peaks associated with exchange cations are shifted upward by increased gas (N2) pressure.
Reference Chlorite Characterization for Chlorite Identification in Soil Clays
Authors: Martin R. Torrence
Published: August 2006

Literature pertaining to differential thermal and X-ray diffraction of chlorite minerals is reviewed. Optical, DTA, and X-ray data for eleven chlorite samples of clinochlore, prochlorite, thuringite, corundophilite, and leuchtenbergite are given. The effect of particle size (105 to −1 μ) on DTA, X-ray diffraction, glycol retention, and cation exchange capacity are given for two thuringites, one clinochlore, and one prochlorite.

Identification of chlorite by DTA in a soil clay containing a mixture of minerals is improbable at the present time except under very favorable circumstances. However, for relatively pure chlorite samples, variations in chemical composition are reflected in the differential thermal curves. The largest change in the thermogram is produced by ferric iron which lowers the peak temperature from 720° C to 610° C. Differences in thermal behavior between low and high ferric iron chlorite species are maintained for any given particle size. Chlorite thermograms obtained by different investigators show much greater variation than the differences in thermograms for other clay minerals determined on different equipment.

X-ray diffraction can be used to positively identify chlorite in a soil clay, (a) by careful analysis of reflections at least as great as 14 Å, and (b) by the influence heat treatment (550° C for 30 minutes) has on the X-ray pattern. Heat treatment produces marked changes in the X-ray pattern of the finer particle size samples and the magnitude of the change effected is greater for high iron chlorites (thuringite) than for low iron chlorites (clinochlore and prochlorite). Olivine is not the recrystallization product for thuringite. The smallest size fractions show no tendency toward vermiculite or montmorillonoid.

Cation exchange capacity for silt size chlorites varies from 4 to 32 m.e./100gm., and for −2 μ chlorite particles from 30 to 47 m.e./100gm. Cation exchange capacities for −2 μ and −1 μ chlorites are essentially the same.

Ethylene glycol retention increases with decreasing particle size. Glycol retention for −2 μ chlorite samples varies from 25 to 40 mg, glycol/gm, clay. For −1 μ chlorite material, glycol retention is 2 to 4 times greater than for −2 μ material.
Water Sorption Properties of Homoionic Montmorillonite
Authors: White W. Arthur
Published: August 2006

Homoionic samples of four montmorillonite clays, selected on the basis of the properties which control their economic uses, were prepared by treating with two normal neutral solutions of ammonium acetate, lithium, sodium, potassium, calcium, and magnesium chloride. Atterberg plastic and liquid limits, slopes of the liquid limit curves, and water sorption curves were determined. Among the results suggested, the following are particularly considered:

1.

The plastic state is reached when enough water is put into the system to fill all the pore space and to supply all the montmorillonite layers with water adequate for rigid layers plus a slight additional amount.

2.

The type of cation is not the only factor which controls the properties of montmorillonite.

3.

The structure of the lattice also appears to determine the properties of montmorillonite.
Peptization Resistance of Selected Samples of Kaolinitic, Montmorillonitic, and Illitic Clay Materials
Authors: Whitehouse U. Grant , Jeffrey Lela M.
Published: August 2006

Variations in the peptization resistance of selected samples of clay mineralogical materials toward alkaline dispersing agents are discussed from a quantitative point of view.

Clay samples, collected from South Carolina, Wyoming, Illinois, New Mexico, South Wales, Great Britain and Cornwall, England were subjected to the action of solutions of Calgon (“sodium hexametaphosphate”), ammonia, sodium hydroxide, sodium carbonate, sodium pyrophosphate, and “sodium lignosulfonate.” The resulting apparent dispersion, in each case, was expressed as a function of the employed concentration and chemical nature of the dispersing agent. Pipette analysis and Oden balance techniques at constant temperature were used to measure the degree of dispersion. All clay samples employed were identified as to type by X-ray diffraction, chemical analysis, thermal analysis, and electron microscopy.

All samples examined exhibited a maximum in apparent dispersion (suspension stability) at a specific concentration of dispersing agent. Such maximum was followed by a sudden decrease in apparent dispersion, i.e., flocculation, at higher concentrations of dispersing agent. Concentrations of dispersing agent were varied in steps of one part per thousand. One hundred and twenty experimental runs were made on each type of material examined. Differences in the degree of apparent dispersion attained by use of different dispersing agents were expressed in terms of a threshold concentration which altered “equivalent diameter” one tenth of a phi unit. Among dispersing agents employed, “sodium lignosulfonate” was found to be least selective of clay mineral type in its peptizing action.

An equation for the calculation of a “peptization resistance factor” is presented. Results obtained by application of this equation indicate that differences in the response of the same clay material to different alkaline dispersing agents may be attributed, in part, to differences in degree of peptization achieved by “threshold mechanisms” of peptization and by “adjustment mechanisms” along the peptization path. Such equation may have future value in the differentiation of marine and terrestrial clay deposits.
Ion Pair Activities in Bentonite Suspensions
Authors: Davis Lannes E.
Published: August 2006

The thermodynamic activities of ion pairs were measured electrometrically in a series of aqueous mixtures of monoionic bentonite and the corresponding chlorides. Ion exchange membranes and Ag-AgCl electrodes were used. The lyotropic order for the various cation species varied somewhat for two different preparations. The apparent relative escaping tendencies of the various cations did not correspond to that usually assumed on the basis of related phenomena: ion exchange selectivity, electromigration velocities, flocculation values or rates, etc.
Clay Minerals in Some Illinois Soils Developed from Loess and Till Under Grass Vegetation
Authors: Beavers A. H. , Johns W. D. , Grim R. E. , Odell R. T.
Published: August 2006

Clay mineral analyses were made of three groups of soil profiles — one developed from Peorian loess overlying Illinoian till — one associated with glacial till of Wisconsin age — one developed on deep to thin loess overlying Wisconsin till. These groups were investigated to determine the influence of parent material and intensity of weathering upon the soil profile development and clay mineral composition.

Montmorillonite, illite, and chlorite are the dominant clay minerals in all the samples studied. In known loess samples, montmorillonite is invariably the most abundant clay mineral component. In the samples of unweathered till of Wisconsin age, illite and chlorite are the abundant clay minerals.
The Effect of Acid and Heat Treatment on Montmorillonoids
Authors: Mathers A. C. , Weed S. B. , Coleman N. T.
Published: August 2006

H-montmorillonite, -beidellite, and -nontronite were found to change spontaneously into Al-clays. Rates of conversion of H- to Al-clay were slow at 0°C, but at temperatures of around 100°C, moist H-montmorillonite changed to Al-saturated montmorillonite within 24 hours. It appeared that Al-ions moved from lattice positions to exchange positions, with octahedral Al moving more rapidly than tetrahedral Al.

Treatment of montmorillonoids with HCl solutions at 80°C resulted in the removal of large quantities of Fe, Mg, and Al. The residue after hot acid treatment appeared to be a mixture of essentially unaltered montmorillonoid and SiO2, rather than a new mineral.

On heat treatment, H- and Al-montmorillonites became largely non-expanding of 300°C, and lost the bulk of the CEC which could be attributed to permanent lattice charge, H- and Al-nontronite and -beidellite, on the other hand, did not suffer irreversible dehydration and loss of CEC until heated to sufficiently high temperatures to cause the expulsion of lattice OH. Montmorillonites with largely octahedral charge had smaller CEC’s after heating to 500°C than did montmorillonites with appreciable tetrahedral charge.
Soil Moisture Tension Measurements: Theoretical Interpretation and Practical Application
Authors: Day Paul R.
Published: August 2006

The tension phenomenon described herein occurs in a wide variety of porous materials, including sands, clays, agricultural soils and porous rocks. When some of the water is removed from a water-saturated porous system, the residual water evidently remains physically interconnected, judging from the fact that water can be transmitted through the system at reduced water content by suction.

The removal of water may result in contraction of the system, as in the case of clay, or in the entry of air, as in the case of sand. The liquid phase and the solid phase in contact with it comprise a closely linked force system. Equilibrium can be established between the system at reduced water content and a separate mass of water at reduced pressure through a porous membrane in contact with both.

The equilibrium tension required in the external water phase is considered an attribute of the moist, porous, system itself. From this point of view, the tension originates through the combined action of the internal forces of the system in a virtual displacement of water. It follows from this and from the principle of virtual work that the tension is numerically equal to the differential work done by the internal forces per unit volume of water absorbed.

The movement of water, under tension, through porous systems represents a special class of flow phenomena in which tensiometers or equivalent devices are required for measuring the hydraulic potential. Flow patterns can be determined in much the same way as in systems characterized by positive hydrostatic pressures, but special attention must be paid to the Darcy coefficient (the capillary conductivity) which varies with the tension.

The theoretical conditions for the equilibrium of water in the soil and for emergence from the soil have been developed in terms of the tension and certain applications have been indicated.

The phenomenon referred to in the soil science literature as moisture tension has been recognized for almost forty years and has been used as a means of explaining the absorption and movement of water in the soil. It is closely related to osmotic pressure but its mechanism cannot in general be identified with the traditional mechanisms of osmotic pressure. Moisture tension has been observed in wet clay soils and in other finely divided porous systems containing interstitial water, but the phenomenon is not confined to colloidal systems, since moist sand and moist porous rock, such as pumice, show similar effects.
Methods of Preparation and Control of Clay Mineral Specimens in X-Ray Diffraction Analysis
Authors: Milne I. H. , Warshaw C. M.
Published: August 2006

The determination of the clay minerals present in mixtures by x-ray diffraction examination of oriented aggregates on glass slides becomes more reproducible and more conclusive when the relative humidity of the air in contact with the specimen is controlled during the recording of the diffraction pattern. The basal diffraction peaks of expanding and partially expanding clay minerals vary considerably in spacing and intensity with normal variations of relative humidity. These variations may be eliminated by the application of a simple modification to standard x-ray equipment. This modification is useful in maintaining a constant relative humidity at values between <1 and 100 percent. Dry air is used to maintain the effects of dehydration by heat and, in many cases, may be used as a substitute for heat treatment. This is especially true for mixed-layer minerals, which give more intense and more reproducible diffraction effects in dry air. Wet air is better, in many instances, than glycerol or ethylene glycol in resolving the basal reflections of montmorillonite and illite in mixtures. More information can be obtained from preparations of mixed-layer minerals and mixtures of clay minerals by recording the diffraction pattern at various stages of hydration.
Correlation of Paper-Coating Quality with Degree of Crystal Perfection of Kaolinite
Authors: Murray Haydn H. , Lyons S. C.
Published: August 2006

Several kaolinite samples were selected for x-ray diffraction studies on the basis of their paper-coating ability. The evaluation of the kaolin clay for paper coating was based on a series of empirical tests including viscosity, resistivity, brightness, and particle-size distribution. The crystallinity of the kaolinites was determined by use of x-ray powder diffraction patterns. In all samples that were good paper coaters, the crystallinity was well developed. Other samples which were poor paper coaters either had poor crystallinity, or, if they had good crystallinity, contained montmorillonite. Crystallinity is not a function of the size fraction. Generally, if the crystallinity is good in the raw sample, then the crystallinity is also good in the < 0.25 micron fraction.

Suitability of kaolinite clay for paper coating varies directly with the perfection of crystallinity and indirectly with the montmorillonite content. Both of these variables can be determined by use of x-ray diffraction data.
The Green Compression Strength of Natural Bentonites
Authors: Bradley W. F.
Published: August 2006

Cored specimens of several commercial bentonite beds were preserved at field moisture levels for laboratory examination. Green strength, water content, and x-ray diffraction character of undisturbed material were found to conform substantially to the relation that strength is proportional to the solid fraction.
Dehydration of Monoionic Montmorillonites
Authors: Rowland R. A. , Weiss E. J. , Bradley W. F.
Published: August 2006

The dehydration of sodium, potassium, lithium, hydrogen, calcium, magnesium, and manganese monoionic montmorillonites (prepared with ion-exchange columns) and a ver-miculite, was examined by the x-ray powder diffraction oscillating-heating method. The position and intensity of each of the first-order basal spacings were measured at intervals of 5° to 10° C from room temperature to 900°C. Position and intensity measurements were made for the first five orders of the basal spacing of the calcium montmorillonite up to 300° C and compared with computed intensities at these spacings. These data are presented as oscillating-heating x-ray diffraction diagrams showing the intensity change with temperature, with important spacing shifts indicated, and as graphs showing the change in spacing with change in temperature.

Like vermiculite, calcium, magnesium, manganese, lithium, and hydrogen montmorillonite have an octahedral coordination of their exchange cation, and upon heating they also pass through two stable hydrates (ca. 14.5 A and 11.5 A). Montmorillonites of the two larger ions, sodium and potassium, have a regular one-water-layer configuration at 12.4 A, which is distinctly different from the 11.5 A hydrate of the smaller ions.

The foreshortened oxygen-oxygen approaches of the lower hydrate (11.5 A) may be accounted for by assuming that the exchange ions take up coordinate positions between silica-oxygen and water levels or, alternatively, that some of the silica tetrahedra are inverted.
Effect of Wetting Agents on the Deformation Behavior of Kaolinite-Water Systems
Authors: Ormsby W. C. , Witucki R. M. , Weyl W. A.
Published: August 2006

An experimental technique was developed for studying the deformation properties of kaolinite-water mixtures, and a study was made of the effects of different wetting agents on the deformation behavior of these mixtures. Particular care was taken to minimize physical effects that could be attributed to preferred orientation of clay particles. Evaluation of different compositions was made in terms of stress-strain diagrams obtained by means of a simple compression plastometer test. Auxiliary studies included sedimentation and filtration experiments of kaolinite-water mixtures containing wetting agents.

The various classes of wetting agents investigated, viz., anionic, cationic and nonionic wetting agents, were found to affect the deformability of clay-liquid mixtures independently of the surface tension of the liquid phase. As compared with water alone, cationic and nonionic reagents decreased and anionic reagents increased the deformability of clay-liquid mixtures.

In general, the sedimentation and filtration properties of kaolinite-water mixtures containing various wetting agents were consistent with the results of the deformation experiments.
Altered Wall Rocks Along vein Deposits in the Central City-Idaho Springs Region, Colorado
Authors: Tooker E. W.
Published: August 2006

Wall-rock alteration along veins in the Central City-Idaho Springs region, Gilpin and Clear Creek Counties, Colorado, superficially resembles alteration around similar base-metal sulfide deposits, but differs in some details. Meso thermal-type veins of early Tertiary age cut deformed Precambrian metasedimentary, igneous, and metamorphosed igneous rocks; the veins contain pyrite, galena, sphalerite, chalcopyrite, and tennantite as principal constituents and minor gold, silver, and uranium minerals. A spatial zonation of ore minerals relates to distinct stages of ore deposition.

Detailed studies show that three of the wall rocks in the area—granodiorite, biotite-mus-covite granite, and biotite-quartz-plagioclase gneiss—are altered to varying degrees and in varying amounts. Clay-mineral formation was a major feature of the process. The alteration sheath around fractures and veins is divided into four gradational but regular zones: (1) Least altered (fresh) rock; (2) weakly altered, hard rock; (3) moderately altered, soft clay-mineral rock—(a) montmorillonite-rich, (b) kaolimte-rich, and (c) illite-sericite-rich; and (4) strongly altered, hard (silicified) rock. The sequence of silicate alteration is believed to relate first to the relative stability of primary mineral structures in the alteration environment, but ultimately to the chemistry of the environment.

The host rocks are significant factors in localization of altered mineral assemblages as they supply the requisite elements for argillic-type alteration. Structures of the host rocks and veins play a prominent role in localization of altered rocks and the zoned ore deposits. Coincidence of alteration and mineralization processes may have more spatial than temporal significance.

A working hypothesis explaining the geological evidence proposes that most alteration was accomplished by meteoric and/or hypogene solutions before ore minerals were deposited. Later solutions of the pyrite stage may have intensified the early zone 4 alteration assemblage close to the source channels, but base-metal sulfide stage solutions were not competent to impress additional alteration effects. Most supergene alteration occurs close to the surface. Therefore, in these areas alteration zonation does not afford a reliable guide to ore.
Types of Mixed-Layer Minerals from Japan
Authors: Sudo Toshio , Hayashi Hisato
Published: August 2006

From x-ray studies, mixed-layer minerals can be classified into regular and random types; the former show a long spacing of about 30 A. Certain clays showing strong powder reflections from long spacings have been considered in detail after treatment with ethylene glycol and/or ignition.

Kurata clay and Hanaoka clay no. 908, showing 29.6 ± 0.2 A spacing, are composed of the following three kinds of lattices: (a) the usual montmoriilonite lattice with the cell height of 15.4 A (M-lattice), (b) the kaolin mineral lattice with cell height of about 7 A (K-lattice), (c) a new lattice with a cell height of 14 A (G-lattice) which is represented by a regular inter stratification between pyrophyllite and gibbsite layers. In these clays Mand G-lattices form partly a regular mixed-layer structure with a 29.6 A spacing and partly a random mixed-layer structure. Hanaoka clay no. 308, showing a 26.6±0.2 A spacing, is composed of a lattice with cell height of 12 A and a chlorite lattice; these form a regular mixed-layer mineral with the long spacing. A random mixed-layer mineral is found in some so-called acid clays. These clays have very broad basal reflections showing random mixed-layer complexes and having almost equal percentages of kaolinite and montmoriilonite layers. The thermal curves and electron micrographs of these clays are discussed.
Vermiculite as a Member in Mixed-Layer Minerals
Authors: Heystek H.
Published: August 2006

X-ray diffraction and differential thermal analysis data are presented for colloid fractions from a soil and shales containing a vermiculite and a montmorillonoid; a chlorite and a vermiculite-chlorite mixed-layer mineral; and a montmorillonoid and a vermiculile-chlorite mixed-layer mineral. The minerals were identified by heating the clay fractions at various temperatures and by treating them with ethylene glycol and/or ammonium chloride.
New data on Sepiolite and Attapulgite
Authors: Mumpton Fred A. , Roy Rustum
Published: August 2006

Hydrothermal studies have failed to yield synthetic attapulgite or sepiolites in the system MgO-Al2O3-SiO2-H2O. However, the natural minerals can be decomposed to yield mont-morillonoids by mild hydrothermal treatment as low as 200°C and probably as low as 100°C. These data indicate that they are metastable and probably could not have formed at these temperatures.

Dry dehydration at 400° and 750°C gave no evidence for the presence of “zeolitic water” in these minerals and failed to establish the existence of “anhydride” phases. The field study of relationships in one sepiolite locality suggests the importance of structural control in the formation of these minerals.
Layer Charge and Interlamellar Expansion in a Muscovite
Authors: White Joe L.
Published: August 2006

Treatment of a muscovite (Delamica) with molten lithium nitrate produced a lowering of the layer charge on the mica. By gradual reduction of the density of surface charge the dependence of interlamellar expansion on the attainment of a critical value of about 6.7 × 104 e.s.u./cm2 was demonstrated in a straightforward manner.
Random Interstratification in Organophilic Bentonites
Authors: McAtee James L.
Published: August 2006

Organophilic bentonites prepared by reacting various amounts of n-laurylamine hydrochloride and dimethyldioctadecyl ammonium chloride with bentonite have been studied by the method of Fourier transforms. The transform curves obtained from the x-ray diffraction patterns of these samples show how different numbers of organic layers between clay laminae are produced by different kinds and amounts of organic material added to the clay. It has been found that as the organic material reacts by base exchange with the clay surfaces, the number of organic layers between each two clay platelets increases in a regular and stepwise manner.