bluuebunny/crossref_metadata_2025 huggingface dataset:
The new middle class meets the creative class
Authors: Flew Terry
Published: August 2006

‘MBA fever’ in China needs to be understood in the wider context of forces driving structural change in China's relation to the global knowledge economy. The rise of a ‘new middle class’ in China is connected to the new claims for cultural leadership of an emergent ‘creative class’, which generates new issues about the relevance of the MBA in China, in terms of its relevance to Chinese economic circumstances, its flexibility and its capacity to respond to accumulation strategies that emphasize innovation, creativity and entrepreneurship.
The belief in ethnic kinship
Authors: Sutterlüty Ferdinand
Published: August 2006

The belief that members of an ethnic group are blood relatives may seem archaic, but it is still very alive today, and it awakens primordial feelings of affiliation. According to this deep-rooted idea of kinship, individuals are only responsible for members of their own ethnic group, and it is only to them that they are obliged to show solidarity. The effects of this belief were seen at two blood drives that the German Red Cross held at a Turkish mosque in the Ruhr region of Germany and that were studied in an ethnographic research project. An analysis shows that the belief in ethnic kinship represents a major barrier to integration and an important factor in perpetuating social inequality among ethnic groups. The Turkish migrants endeavored to initiate an exchange of gifts among quasi-relatives and based their integration strategy on this objective, but their efforts to establish reciprocal exchange relations provoked resistance in the autochthonous population. Herein lies the broader relevance of the primordial belief in blood relations, which constitutes a deep symbolic dimension of social inequality.
Fast simulated annealing inversion of surface waves on pavement using phase-velocity spectra
Authors: Ryden Nils , Park Choon Byong
Published: August 2006

The conventional inversion of surface waves depends on modal identification of measured dispersion curves, which can be ambiguous. It is possible to avoid mode-number identification and extraction by inverting the complete phase-velocity spectrum obtained from a multichannel record. We use the fast simulated annealing (FSA) global search algorithm to minimize the difference between the measured phase-velocity spectrum and that calculated from a theoretical layer model, including the field setup geometry. Results show that this algorithm can help one avoid getting trapped in local minima while searching for the best-matching layer model. The entire procedure is demonstrated on synthetic and field data for asphalt pavement. The viscoelastic properties of the top asphalt layer are taken into account, and the inverted asphalt stiffness as a function of frequency compares well with laboratory tests on core samples. The thickness and shear-wave velocity of the deeper embedded layers are resolved within 10% deviation from those values measured separately during pavement construction. The proposed method may be equally applicable to normal soil site investigation and in the field of ultrasonic testing of materials.
Accounting for spatially variable resolution in electrical resistivity tomography through field-scale rock-physics relations
Authors: Singha Kamini , Moysey Stephen
Published: August 2006

A number of issues impact electrical resistivity tomography (ERT) inversions: how ERT measurements sample the subsurface, the nature of subsurface heterogeneity, the geometry selected for data collection, the choice of data-misfit criteria, and regularization of the inverse problem. Lab-scale rock-physics models, typically used to estimate solute concentration from ERT, do not accommodate or account for these issues and therefore produce inaccurate geophysical estimates of solute concentrations. In contrast, the influence of measurement sensitivity and inversion artifacts can be captured by pixel-based rock-physics relationships, determined using numerical analogs that recreate the field-scale ERT experiment based on flow and transport modeling and a priori data. In the 2D synthetic example presented here, where ERT is used to monitor the transport of a saline tracer through the subsurface, improved estimates of concentration are obtained when field-scale rock-physics relationships based on numerical analogs are used.
Modeling and inversion of PS-wave moveout asymmetry for tilted TI media: Part 2 — Dipping TTI layer
Authors: Dewangan Pawan , Tsvankin Ilya
Published: August 2006

Dipping transversely isotropic layers with a tilted symmetry axis (TTI media) cause serious imaging problems in fold-and-thrust belts and near salt domes. Here, we apply the modified [Formula: see text] method introduced in Part 1 to the inversion of long-offset PP and PS reflection data for the parameters of a TTI layer with the symmetry axis orthogonal to the bedding. The inversion algorithm combines the time- and offset-asymmetry attributes of the PSV-wave with the hyperbolic PP- and SS-wave moveout in the symmetry-axis plane (i.e., the vertical plane that contains the symmetry axis).

The weak-anisotropy approximations for the moveout-asymmetry attributes, verified by numerical analysis, indicate that small-offset (leading) terms do not contain independent information for the inversion. Therefore, the parameter-estimation algorithm relies on PS data recorded at large offsets (the offset-to-depth ratio has to reach at least two), which makes the results generally less stable than those for a horizontal TTI layer in Part1. The least-resolved parameter is Thomsen’s coefficient [Formula: see text]that does not directly influence the moveout of either pure or converted modes.

Still, the contribution of the PS-wave asymmetry attributes helps to constrain the TTI model for large tilts [Formula: see text] of the symmetry axis [Formula: see text]. The accuracy of the inversion for large tilts can be improved further by using wide-azimuth PP and PS reflections. With high-quality PS data, the inversion remains feasible for moderate tilts [Formula: see text], but it breaks down for models with smaller values of [Formula: see text] in which the moveout asymmetry is too weak. The tilt itself and several combinations of the medium parameters (e.g., the ratio of the P- and S-wave velocities in the symmetry direction), however, are well constrained for all symmetry-axis orientations.

The results of Parts 1 and 2 show that 2D measurements of the PS-wave asymmetry attributes can be used effectively in anisotropic velocity analysis for TTI media. In addition to providing an improved velocity model for imaging beneath TTI beds, our algorithms yield information for lithology discrimination and structural interpretation.
A methodology for 7D warping and deformation monitoring using time-lapse seismic data
Authors: Hall Stephen A.
Published: August 2006

A methodology is presented for vector analysis of the image displacements (warping) between successive 3D seismic image volumes that provides 7D analysis (including lateral and vertical displacements) of in situ subsurface deformation around hydrocarbon reservoirs. The key challenges are (1) assessment of just vertical shifts is insufficient, and vector displacements should be determined; (2) robust vertical displacements can usually be derived, but lateral shifts are less well defined because of the generally smooth data character in a horizontal/horizon plane; (3) subvoxel resolution is necessary for correct matching and deformation analysis; (4) velocity and strain effects are intrinsically combined in time-lapse seismic images; (5) separation of accumulated and local effects is necessary; (6) apparently coherent and smooth displacement fields do not necessarily provide good strain analysis; (7) warping is easily degraded by noise, and good cross-matching is a prerequisite. To address these challenges, a full 3D, local warp vector derivation methodology is proposed, which involves (1) constraint using prior estimates, (2) local refinement with subvoxel resolution, and (3) 3D and vectorial conditioning using a deformable mesh with sensitivity to image-match quality. The warping approach is extended to separate accumulated from local effects and to analyze in situ deformation based on the displacement vector volume. This is achieved by a finite-element approach to determine an elemental pseudostrain tensor field and an iterative procedure to separate the pseudostrain into velocity and strain components. The approach up to the strain analysis, is demonstrated using a real data example, which indicates the potential of the methodology (accumulated overburden effects are separated to reveal a local compaction signature in the reservoir), but realistic, quantitative values of strain have not yet been realized.
PS-wave moveout inversion for tilted TI media: A physical-modeling study
Authors: Dewangan Pawan , Tsvankin Ilya , Batzle Mike , van Wijk Kasper , Haney Matthew
Published: August 2006

Mode-converted PS-waves can provide critically important information for velocity analysis in transversely isotropic (TI) media. We demonstrate, with physical-modeling data, that the combination of long-spread reflection traveltimes of PP- and PS-waves can be inverted for the parameters of a horizontal TI layer with a tilted symmetry axis. The 2D multicomponent reflection data are acquired over a phenolic sample manufactured to simulate the effective medium formed by steeply dipping fracture sets or shale layers.

The reflection moveout of PS-waves in this model is asymmetric with respect to the source and receiver positions, and the moveout-asymmetry attributes play a crucial role in constraining the TI parameters. Applying the modified [Formula: see text] method to the PP and PS traveltimes recorded in the symmetry-axis plane, we compute the time and offset asymmetry attributes of the PS-waves along with the traveltimes of the pure SS reflections. The algorithm of Dewangan and Tsvankin is then used to invert the combination of the moveout attributes of PP-, SS-, and PS-waves for the medium parameters and the thickness of the sample. It should be emphasized that the pure-mode (PP and SS) traveltimes alone are insufficient for the inversion, even if 3D wide-azimuth data are available.

Our estimates of the symmetry axis tilt and layer thickness almost coincide with the actual values. The inverted model is also validated by reproducing the results of transmission experiments with both P- and S-wave sources. The transmitted SV wavefield exhibits a prominent cusp (triplication) accurately predicted by the parameter-estimation results.
Detection and extraction of fault surfaces in 3D seismic data
Authors: Cohen Israel , Coult Nicholas , Vassiliou Anthony A.
Published: August 2006

We propose an efficient method for detecting and extracting fault surfaces in 3D-seismic volumes. The seismic data are transformed into a volume of local-fault-extraction (LFE) estimates that represents the likelihood that a given point lies on a fault surface. We partition the fault surfaces into relatively small linear portions, which are identified by analyzing tilted and rotated subvolumes throughout the region of interest. Directional filtering and thresholding further enhance the seismic discontinuities that are attributable to fault surfaces. Subsequently, the volume of LFE estimates is skeletonized, and individual fault surfaces are extracted and labeled in the order of decreasing size. The ultimate result obtained by the proposed procedure provides a visual and semantic representation of a set of well-defined, cleanly separated, one-pixel-thick, labeled fault surfaces that is readily usable for seismic interpretation.
Sulfated Zirconia-catalyzed One-pot Benign Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones under Microwave Irradiation
Authors: Kumar Dalip , Sundaree M Swapna , Mishra Braja Gopal
Published: August 2006

Sulfated zirconia has been demonstrated as an efficient catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones under microwave irradiation and conventional heating. The solid acid catalyst is found to be highly active for the one-pot condensation of aldehydes, urea and β-dicarbonyl compound, affording variety of 3,4-dihydropyrimidin-2(1H)-ones in excellent yields with high purity. The low cost catalyst has exhibited remarkable reactivity and recycled without any significant loss of activity.
A Practical Method for the Preparation of 4-Nitrogen-substituted Benzoic Acids
Authors: Shinozuka Tsuyoshi , Nakao Akira , Saito Keiji , Naito Satoru
Published: August 2006

An efficient and practical method for the preparation of 4-nitrogen-substituted benzoic acids is described. Our method consists of the aromatic substitution of 2,2,2,4′-tetrafluoroacetophenone with amines, followed by haloform reaction to the benzoic acids. In this method, even though for the less nucleophilic 7-, 8-, and 9-membered amines 1 equiv. was used, corresponding benzoic acids were obtained in moderate to excellent yield. As the experimental procedure including purification is simple, this method is applicable to large-scale syntheses.
Reviews of the 2006 Economic Report of the President
Authors: Auerbach Alan , Blank Rebecca , Feldstein Martin , Katz Michael , Rogoff Kenneth
Published: August 2006

Editor's Note

The Journal of Economic Literature (JEL) regularly reviews books of interest to the economics profession. The Economic Report of the President (ERP) falls under that purview. I have asked a handful of very prominent economists to review the 2006 ERP. Reviewers were chosen to reflect expertise on what I guessed would be key issues. The ERP in principle should provide an accurate assessment of the consensus professional views of economists on any given issue, based on the research to date. Reviewers were asked to evaluate whether the discussion in the ERP in fact accurately summarizes what we as economists know?

Reviewers were given free rein over what material they would review in the ERP but were urged to focus on their areas of particular expertise.

In the reviews that follow, Martin Feldstein reviews the overview chapter as well as topics relating to macroeconomics. Alan Auerbach reviews the ERP's discussion of tax-related issues, while Ken Rogoff reviews the ERP's discussion of international economic topics. Rebecca Blank writes on labor market issues in the ERP, and Michael Katz reviews the ERP's discussion of health care issues.

Many thanks to the reviewers for the quick turnaround.
Behavioral Economics Comes of Age: A Review Essay on Advances in Behavioral Economics
Authors: Pesendorfer Wolfgang
Published: August 2006

Advances in Behavioral Economics contains influential second-generation contributions to behavioral economics. Building on the seminal work by Kahnemann, Strotz, Thaler, Tversky, and others, these contributions have established behavioral economics as an important field of study in economics. In this essay, I discuss aspects of the research strategy and methodology of behavioral economics, as exemplified by the contributions to Advances.
The Shortest-Path Problem with Resource Constraints and k-Cycle Elimination for k ≥ 3
Authors: Irnich Stefan , Villeneuve Daniel
Published: August 2006

The elementary shortest-path problem with resource constraints (ESPPRC) is a widely used modeling tool in formulating vehicle-routing and crew-scheduling applications. The ESPPRC often occurs as a subproblem of an enclosing problem, where it is used to generate implicitly the set of all feasible routes or schedules, as in the column-generation formulation of the vehicle-routing problem with time windows (VRPTW). As the ESPPRC problem is NP-hard in the strong sense, classical solution approaches are based on the corresponding nonelementary shortest-path problem with resource constraints (SPPRC), which can be solved using a pseudo-polynomial labeling algorithm. While solving the enclosing problem by branch and price, this subproblem relaxation leads to weak lower bounds and sometimes impractically large branch-and-bound trees. A compromise between solving ESPPRC and SPPRC is to forbid cycles of small length. In the SPPRC with k-cycle elimination (SPPRC-k-cyc), paths with cycles are allowed only if cycles have length at least k + 1. The case k = 2 forbids sequences of the form i − j − i and has been successfully used to reduce integrality gaps. We propose a new definition of the dominance rule among labels for dealing with arbitrary values of k ≥ 2. The numerical experiments on the linear relaxation of some hard VRPTW instances from Solomon’s benchmark show that k-cycle elimination with k ≥ 3 can substantially improve the lower bounds of vehicle-routing problems with side constraints. The new algorithm has proven to be a key ingredient for getting exact integer solutions for well-known hard problems from the literature.
Segmental Pattern Discovery in Music
Authors: Conklin Darrell , Anagnostopoulou Christina
Published: August 2006

In this paper we describe a new method for discovering recurrent patterns in a corpus of segmented melodies. Elements of patterns in this scheme do not represent individual notes but rather represent melodic segments that are sequences of notes. A new knowledge representation for segmental patterns is designed, and a pattern discovery algorithm based on suffix trees is used to discover segmental patterns in large corpora. The method is applied to a large collection of melodies, including Nova Scotia folk songs, Bach chorale melodies, and sections from the Essen folk song database. Patterns are ranked using a statistical significance method that integrates pattern self-overlap, length, and frequency in a corpus into a single measure. A musical interpretation of some of the statistically significant discovered patterns is presented.
Slicing It All Ways: Mathematical Models for Tonal Induction, Approximation, and Segmentation Using the Spiral Array
Authors: Chew Elaine
Published: August 2006

This paper presents the spiral array model and its associated algorithms for tonal induction, approximation, and segmentation. The spiral array is a geometric model for tonality that clusters perceptually similar tonal entities. The model summarizes music information as interior points inside an array of spirals. Distances in the spiral array space are used to quantify tonal similarity. The paper traces the evolution, and presents general forms, of the existing algorithms for key finding, pitch spelling, and segmentation, and proposes a new O(n) algorithm, Argus, for tonal segmentation. The proposed algorithm computes a value that quantifies the discrepancy between the local contexts in the future and past at each point in time. Discrepancy values exceeding control thresholds are shown to mark the segmentation boundaries of the test set that concur with expert analyses. A number of window sizes and threshold settings are investigated. The algorithm is demonstrated using Edward MacDowell’s To A Wild Rose and tested on Franz Schubert’s Allegretto from Moment Musical D780 No. 6 and Thema from Impromptu D935 No. 4. The algorithm accurately locates tonal boundaries in all three case studies.
Ion Exchange Reactions of Clays
Authors: Lewis D. R.
Published: August 2006

It has been recognized for many years that many aspects of clay
technology including soil treatment and drilling mud treatment must remain
in an essentially empirical state until a basis for the understanding of ion
exchange reactions is established.

Much of the work on ion exchange reactions of clays in the past has been
directed toward establishing total exchange capacities or determining the
ionic distribution empirically. This information in general is not suitable
for the evaluation of hypotheses designed to provide a basis for
understanding the exchange reaction. When the techniques for characterizing
the various clay minerals offered the possibility of quantitative study, the
solution and exchanger phase contributions to the ionic distribution could
be experimentally evaluated in principle. The particular experimental
techniques which have been used to measure ionic distribution, however,
frequently neglected observations which are essential if the data are to he
used for testing and developing theories of ion exchange. It is now well
recognized that molecular adsorption, complex ion formation in solution, and
ion-pair formation between a mobile solution ion and a fixed exchanger group
may occur in addition to the ion exchange reaction. Therefore, if the data
are to be useful to develop theories of ion exchange, the whole system must
be selected to minimize such extraneous contributions. On the basis of
recent theoretical work, various experimental techniques art; evaluated from
the point of view of their suitability for equilibrium ion distribution
studies.

The mass action, adsorption isotherm, and Gibbs-Donnan equilibrium
formulations of the ion exchange theory are discussed as they may apply to
clay systems. Recent progress is summarized in (1) solution thermodynamics
of mixed electrolytes as it is relevant to ion exchange processes of clays,
(2) the contributions of non-ideality of the clay exchanger phase, and (S)
the work of swelling of clays which affects the ionic distributions in ion
exchange reactions.

It is concluded that the parameters which relate to the solid phase of
the exchanger and those which relate to the solution are now sufficiently
well recognized that future experiments can be planned which may more
realistically provide an experimental basis for understanding the process of
equilibrium ion exchange distributions in aqueous clay-electrolyte
systems.
Interpretation of Chemical Analyses of Clays
Authors: Kelley W. P.
Published: August 2006

As a means of distinguishing between the broad groups of flay minerals,
chemical analysis may be a valuable supplement to other methods, but rarely
will it remove the necessity for other methods, X-ray analysis in
particular. The two- and three-layer clay minerals may be distinguished by
the SiO2 ·
Al2O3 ratio or
SiO2 · sesquioxide ratio, but these ratios do not
provide criteria for dividing either class. Among the three-layer clays,
which embrace montmorillonite, nontronite, and the diverse hydrous micas,
non-exchangeable K is a better criterion. It seems probable that
montmorillonite, as found in bentonite deposits, does not contain
significant amounts of non-exchangeable K, whereas all known hydrous micas
contain significant, although widely variable, amounts of non-exchangeable
K.

The greatest value of chemical analysis inheres in the fact that by
means of calculation the specific nature of the isomorphism may be
determined. But the degree of confidence that can justifiably be placed in
the calculated isomorphism depends on the purity of the sample analyzed.
SiO2 as impurity may be shown by an excess of
calculated Si++++ ions, or by a deficiency of
octahedral cations. It also affects the calculated isomorphism of the
tetrahedral layers of the lattice by reducing its Al content.

On the other hand, Al2O3 as
impurity affects the calculation in the opposite way; that is, it reduces
the number of Si++++ ions per unit cell, while
increasing both tetrahedral and octahedral Al+++ ions.
Fe as impurity has essentially the same effect as Al.

In some samples it is possible to detect SiO2 as
impurity by means of calculation.
Interpretation of Chemical Analyses of Montmorillonites
Authors: Osthaus Bernard B.
Published: August 2006

Particles of montmorillonite representing a considerable range of sizes
wow separated from crude hentonites by means of sedimentation and
supercentrifugation. Except for the effect of impurities, it was found that
base-exchange capacity was independent of particle size.

The ratios of the several exchangeable cations on the niontmorillonites
vary widely as they occur in the crude bentonites. Sodium is the dominant
cation in the Clay Spur, Wyominj, and Belle Fourche, South Dakota, samples;
calcium in those from Polkville, Mississippi, Santa Rita, New Mexico,
Chambers, Arizona, and Plymouth, Utah; in the Little Rock, Arkansas, sample,
hydrogen is the most abundant exchangeable cation. The hydrogen ion is
reflected in the low pH of the sample. The Otay, California, and Merritt,
British Columbia, samples contain more nearly equal amounts of exchangeable
calcium, magnesium, and sodium.

Formulae calculations indicate that these samples present a rather wide
range in isomorphism and, in consequence, the source of the negative charge
on the lattice is widely variable. However, the calculated charges depend,
to a large extent, on the purity of the sample. Evidence is presented that
silicon dioxide in some form is the most abundant impurity and that
significantly large amounts of uncombined silicon dioxide may be present in
the finest fractions. The Merritt, British Columbia, sample was found to
contain about 35 percent cristobalite. The corresponding particle size
fraction from Amory, Mississippi, bentonite contains considerable hydrous
mica. Unless allowance is made for impurities, the calculated lattice
positions of the electro-positive atoms, and therefore the formula derived
therefrom, are essentially meaningless.
Petrographic Study of Clay Materials
Authors: Grim Ralph E.
Published: August 2006

Some investigntors have used petrographic methods as the sole means of
making clay mineral analyses, whereas others have considered petrographie
metliods to be useless for materials as fine grained as clays. The value of
the method lies between these extremes. It has consideralde value, but it
has limitations and must be used with cantion.

By the use of varions auxiliary techniques it is usually possible to
obtain fairly precise values for the indices of refraction and birefringence
of the clay mineral components of a clay material. Frequently an
interference figure can be obtained which yields farther data on the optical
characteristics. The presence of very fine non-clay minerals, such as quartz
and carbonate, and organic material and iron oxide or hydroxide may prevent
the making of satisfactory optical measurements.

It is necessary to decide if the optical data obtained arc influenced by
contamination with nonclay minerals, and if they indicate a single clay
mineral or mixture of clay minerals. Fortunately the optical values
themselves and the character of the particles on which they were determined
give good clues regarding purity and monomineral characteristics.

Optical data in general will not permit the detection of relatively
small amounts of a clay mineral in a clay mineral mixture. Also such data
may l)e very misleading in studies of mixed-layer clay minerals.

In addition to optical data, petrographic studies of clay materials
yield other important information. They are of value in determining the
texture of the rock and the relative abundance and size of the nonclay
minerals. In general microscopic studies are easy to perform and the
probable value from them is so great, that they should be made in all clay
material researches.
Physical-Chemical Properties and Engineering Performance of Clays
Authors: Mielenz Richard C. , King Myrle E.
Published: August 2006

Fabric (texture and structure) and minpralogic composition determine the
response of clays and shales to events occurrins during construction and
operation of engineering works. A new system of classification of the fabric
of earth materials is proposed. Characteristic minpralogic composition of
clays and shales, especially in the western United States, is described.
Fabric and composition are correlated with soil mechanics properties and
engineering performance. Needed research on clays and shales as a basis for
design, construction, and maintenance of engineering structures is
emphasized.
The Origin of Missouri Fire Clays
Authors: Keller W. D. , Westcott James F. , Bledsoe A. O.
Published: August 2006

The origin of Missouri fire clays is interpreted from the testimony of the clays in terms of the geologic setting in which they were deposited and developed. Hence, the approach to the interpretation is fundamentally that of sedimentary petrology, rather than economic geology. The clays, as sedimentary rocks, are considered to be the products (mineralogic and geologic) resulting from the responses of their source materials to the energetics of the physical and chemical environments which were impressed upon them during the time interval of their deposition and diagenesis.

The fire clays are inferred to have a sedimentary origin; it is believed that their present-day characteristics were essentially developed in the time intervals of the Cheltenham to pre-Fort Scott (Pennsylvanian) age. The different varieties of fire clay are interpreted as different lithofacies within a continuous Cheltenham deposit. The high-alumina facies (diaspore-burley and boehmite) appears to have been formed by severe leaching on a relatively stable land area, whereas the kaolinitic-illitic facies (semi-plastic to semi-flint clay) seem to characterize products formed near the margin of a slowly sinking depositional region. Both processes of destruction and construction (“katamorphism” and “anamorphism,” as used by Van Hise, 1904) appear to have operated in the genesis of the clay minerals.

Evidence points toward a negative Eh and an approximately neutral to slightly acid pH during the formation of the clays. The presence of diaspore and boehmite and the absence of gibbsite in the high-alumina clay are interpreted as indications of leaching of clay minerals under waterlogged conditions. Diaspore may inherit part of the crystal structure and energy of the kaolinite from which it was derived.
Hydrated Halloysite in Blue Hill Shale
Authors: Swineford Ada , McNeal John D. , Crumpton Carl F.
Published: August 2006

Nodules of alunite and hydrated halloysite occur in the upper part of the Cretaceous Blue Hill shale at three localities in west-central Kansas. They have formed at the contact of septarian concretions with the shale and are associated with gypsum. The nodules are judged to have been formed by the action of sulfuric acid from pyrite on the potassium-bearing minerals of the Blue Hill shale, perhaps under special conditions of pH and Eh produced locally by the presence of septaria.

The minerals were studied and identified by x-ray diffraction, thermal data, chemical analysis, and electron and light microscopy.
Clay Minerals in a Limestone Soil Profile
Authors: Carroll Dorothy , Hathaway John C.
Published: August 2006

The clay minerals in a soil developed from Lenoir limestone (Ordovician) in Augusta County, Va., are kaolinite and chlorite. The Lenoir limestone contains clay partings consisting of hydrous mica, and the clay in the soil is considered to be residual from that in the parent limestone and modified by soil-forming processes (podzolic). X-ray diffraction patterns of the clay fraction (<2μ) from samples from different positions in the profile show a reduction in hydrous mica and an increase in kaolinite and chlorite content as the A horizon is reached. Partial chemical analyses of the whole soil and of the clay fractions are given, as well as pH and ion-exchange capacity determinations. The silica-alumina ratios are similar to those characteristic of podzolic soils, and excess silica in the A horizon accumulates as recrystallized quartz together with chert which is considered to be residual from the limestone. Mechanical analyses by the standard pipette method show that the quantity of clay in the soil varies from 17 percent at the surface to 61 percent at 26 inches (C horizon).
Preliminary Study of the Effects of Water Vapor Pressure on Thermograms of Kaolinitic Soils
Authors: Stone Robert L.
Published: August 2006

Kaolinites found in soils generally give poorer thermograms than commercial kaolins. When run under dynamic steam atmospheres up to 90 psi, the endothermic peaks are sharpened and moved upward; the exotherm is made less intense and moved downward. Because of the effects observed, the method promises to be of interest in theoretical studies of hydrates and hydroxides.
X-Ray Diffraction Criteria for the Characterization of Chloritic Material in Sediments
Authors: Bradley W. F.
Published: August 2006

Recent surveys of clay mineral assemblages in argillaceous sediments have indicated that chloritic minerals are of more frequent occurrence and of greater significance than was formerly recognized.

The wide latitude of compositional variations within the chlorite crystallization scheme introduces enough complexity into the x-ray diffraction identification and characterization of these minerals that a detailed description of a few typical clay mineral associations seems justified.

For the simplest cases, in which resolution of diffraction features from entirely chloritic grains can actually be demonstrated, analyses may be highly reliable. Further, for many unresolved instances, simple heat treatments effect reliable identifications.

For more complicated assemblages, in which coherently scattering domains are mixtures within themselves, individually planned heating or swelling reactions may become necessary.

Typical natural examples are illustrated, for which apparently proper distinctions have been made for characterizing associations on mono- and mixed-clay mineral grains.
New Data on the Composition and Identification of Chlorites
Authors: Nelson Bruce W. , Roy Rustum
Published: August 2006

A series of clay minerals with a 7A series of reflections has been shown to exist in the MgO-Al2O3-SiO2-H2O system. It has been demonstrated both on synthetic and natural samples that these minerals are polymorphous with the 14A-series chlorite minerals. Widespread occurrence of these minerals in nature is expected. The polymorphic relationship found clarifies the whole picture of the isomorphism of the chlorites. The problem of nomenclature of these 7 A series minerals is examined and the term “septechlorites” hesitantly proposed.

On the basis of some experimental work it is shown that the currently adopted procedure for the identification of chlorites is not generally valid, and that the factors of time, temperature, composition and particle size are of crucial importance in such procedures.
The Relation Between “Illite,” Beidellite, and Montmorillonite
Authors: Foster Margaret D.
Published: August 2006

Formulas calculated from analyses, written in the fractional notation used by Ross and Hendricks, and with a notation of tetrahedral and octahedral charge, reveal relationships between the hydrous micas called “illite,” montmorillonites (using the term in the restricted sense), and beidellites not otherwise apparent. These relationships are shown graphically by means of histograms made up of five columns, representing respectively, total charge, tetrahedral charge, octahedral charge, potassium, and water.

“Illites” have a much higher total charge and a much higher tetrahedral charge than montmorillonites, of which the tetrahedral charge is usually insignificant. Consequently simple removal of fixed K and its replacement by exchangeable cations would not convert an “illite” to a montmorillonite nor would mere fixation of K between the layers of a montmorillonite result in the formation of an “illite” like any that have been described.

From the standpoint of octahedral-tetrahedral charge relationships, beidellites and “illites” should be more similar than montmorillonites and “illites.” However, considerable doubt has been cast by Grim and Rowland on the purity of most of the materials that have been called beidellites; they interpreted the differential thermal curves of the beidellites examined by them as indicating mixtures of kaolinite or halloy-site, “illite,” and montmorillonite. Formulas based on calculated mixtures of these minerals in varying proportions were very similar to formulas calculated from analyses of the so-called beidellites. Thus the existence of a montmorillonite clay like that which would be formed if the fixed K in “illite” were removed and replaced by exchangeable cations has not been authenticated and the concept that montmorillonite and “illite” are analogous except for the presence or absence of nonexchangeable potassium is misleading and is an oversimplification of the relationship between the two groups of minerals.
The Thermodynamics of Ion Exchange on Clay Minerals. A Preliminary Report on the System Montmorillonite-Cs-Sr
Authors: Thomas Henry C. , Gaines George L.
Published: August 2006

A discussion is given of the advantages of the thermodynamic approach in the study of clay-ion-water systems. Generally valid equations for the description of the systems are given, and the relative significance of the osmotic terms is roughly assessed. The principal theoretical and experimental problem is the determination of the initial slopes of the exchange isotherms, and a formal method for handling this difficulty is described. Preliminary results on the system montmorillonite-cesium-strontium are used for illustrative purposes.
Colloid Science of Montmorillonites and Bentonites
Authors: Hauser Ernst A. , Colombo Umberto
Published: August 2006

In 1847 the name “montmorillonite” was given to a rose-red, clay-like mineral forming nests in a brown clay at Montmorillon, France. The first analysis, reported by Salvetat, gave 49.4 percent to SiO2, 19.7 percent to Al2O3, 0.8 percent to Fe2O3, 0.27 percent to MgO, 1.5 percent to CaO, 1.5 percent to alkalies, and 25.67 percent to H2O. Much later a substance which was originally called “taylorite” after William Taylor, who was the first to draw attention to it, was finally designated as “bentonite” because it was first found in the Fort Benton series of rocks in Montana. The most characteristic mineral component of bentonite is crystalline and definitely montmorillonite.

The chemical analyses of Wyoming bentonite and hectorite are compared with those of three different calcium bentonite deposits. The importance of more up-to-date crystal chemical considerations is discussed. The electrophoretic properties of bentonites are explained on the basis of the available counter ions. The formation of thixotropic bentonite gels is discussed in detail and proof is offered to show why calcium bentonites do not give thixotropic systems.

The base-exchange capacities of sodium-bentonites and of calcium-bentonites and their differences are explained on the basis of two different methods of determining this phenomenon.

Ultra- and electron photomicrographic studies reveal the difference between montmorillonites and the various types of bentonites now known. Most striking is the fact that most bentonites, specifically calcium bentonites, contain several different types of clayey minerals.

The most probable cause of the formation of bentonitic clays as well as of true montmorillonite is referred to and discussed.
Mathematical Analysis of a Layer Extraction Method for Separating Clay-Size Material from Soils
Authors: Chu T. Y. , Davidson D. T. , Sheeler J. B.
Published: August 2006

This paper presents a layer extraction method for obtaining a representative sample of clay-size material from a soil suspension. This method is especially advantageous in preparing a sample of relatively large size, and the procedure is simpler than that of the decantation method, a comparable method of extraction.

In the layer method, the position and the thickness of the layer to be extracted from a soil suspension can be varied and one or more extractions can be made. The effect of these variables on the size composition and the quantity of the extracted material is analyzed mathematically. Based upon such an analysis, the proper position and thickness of the layer and the desirable number of extractions can be determined to suit the requirements of a particular test.
The Mechanism of the Deformation of Clay
Authors: Buessem W. R. , Nagy Bartholomew
Published: August 2006

Kaolinite-water mixtures, containing from 23 percent to 33 percent water, were subjected to compression plastometer tests and their plasticity was studied by means of the calculated strain-stress functions. X-ray diagrams taken of the compressed samples showed that an oriented texture developed during the compression, i.e., the basal planes of the flaky clay particles were arranged parallel to a plane normal to the direction of the applied stress. For the purpose of discussion the concept of the “plastic unit cell” is introduced. The “plastic unit cell” is a cubic volume element, the faces of which are perpendicular to the three principal stresses. The size of the “plastic unit cell” is very small as compared with the size of the macroscopic sample but large as compared with the size of one clay particle. It is the smallest unit for all considerations where macroscopic strain and stress distributions are involved. For all considerations involving the correlation between the characteristic strain-stress function of the material, the motions of the clay particles and water, and the forces present between the particles, the “plastic unit cell” is the largest unit.

The clay particle in itself is rigid and, therefore, it cannot undergo the same deformation as does the “plastic unit cell”. All of the clay particles present in a “plastic unit cell” together can go through a series of motions (translations and rotations) which, in effect, simulate the deformation of the “plastic unit cell”. In the case of the compression test, the translatory and rotatory movements of the clay particles lead to the development of the oriented texture.
Weathering According to the Cationic Bonding Energies of Colloids
Authors: Graham E. R.
Published: August 2006

A study was made of the energy changes of several colloidal systems in relation to weathering.

The total energy change associated with pH, total hydrogen, and bonding energy involved in the weathering of natural phosphates was established by mixing particles of apatite with hydrogen systems of amberlite (I.R. 120), bentonite clay, Putnam clay, kaolinite, and humus. Mixtures of potassium-saturated bentonite, sodium-saturated bentonite, and powdered rock phosphate were also investigated for weathering changes.

The amount of phosphorus weathered was related to hydrogen bonding at the outset and to calcium bonding energy of the colloidal system. H-amberlite, which has the highest bonding energy for calcium of the systems studied, was most effective in weathering phosphate minerals. H-humus, which has the lowest bonding energy for calcium was least effective as a weathering agent. The clay minerals weathered according to the relative energy levels resulting from the consideration of both hydrogen and calcium bonding energies. Bentonite clay was the most effective weathering agent; Putnam clay intermediate, and kaolinite the least effective. Bentonite clay saturated with potassium or sodium was effective as a phosphate mineral weathering agent.
A Study in Morphology by Electron Diffraction
Authors: Sand L. B. , Comer J. J.
Published: August 2006

A stabilized halloysite-glycerol complex was studied by electron microscope and electron diffraction techniques. The basal reflection was found to be 10.7 Å by both electron diffraction and X-ray diffraction analyses. Electron micrographs of the expanded lattice (halloysite-glycerol complex) were not different from those of the collapsed lattice (halloysite). On the basis of the tubes evident in the micrographs and the fact that the basal reflection was present in the transmission electron diffraction pattern, it was established that the halloysite-glycerol complex is tubular. Since this complex has an expanded lattice 0.6 Å greater than hydrated halloysite, it is believed that hydrated halloysite (endellite) is tubular as postulated by Bates, Hildebrand and Swineford.
The Reversible Dehydroxylization of Clay Minerals
Authors: Jonas Edward C.
Published: August 2006

Rehydroxylization of the anhydrous modification of dioctahedral montmorillonites can be carried out under DTA conditions with controlled atmosphere techniques. The structural character of the rehydrate prepared in this way is determined from X-ray and DTA data. The mechanism of the reactions by which the rehydrate can be formed is also considered. Thermal analysis curves of the rehydrate form of several pure mont-morillonite samples failed to show any large variation such as is shown by the curves of the original clays themselves. The possibility is considered that such large variations in the dehydroxylization curves of montmorillonites are related to structural instead of compositional variations within the sample. It is suggested that montmorillonites showing two reactions attributable to dehydroxylization may be mixtures of the rehydrate form and montmorillonite.
Anomalies in the Ethylene Glycol Solvation Technique Used in X-Ray Diffraction
Authors: Kunze G. W.
Published: August 2006

X-ray diffraction results are presented to show that some montmorillonites will not retain two layers of ethylene glycol in the interlayer space when dried under atmospheric conditions. Diffraction data obtained from such samples of montmorillonite may erroneously be attributed to mixed layer minerals. Studies have shown however that this difficulty may largely be overcome by initially saturating the sample with ethylene glycol by the vaporization technique described, after which the sample is placed in a saturated atmosphere of ethylene glycol for a period of 12–24 hours to come to equilibrium and then irradiated.
Swelling of Clay under Pressure
Authors: Nahin Paul G.
Published: August 2006

An experimental technique for studying the swelling of clay under constraint and some preliminary results for the swelling of Wyoming bentonite in several media are presented and discussed. Fractionated, powdered clay is mixed with an equal weight of non-swelling microporous porcelain, which serves to distribute the swelling agent rapidly and uniformly. The mix is compacted in a cell at high pressure and permitted to imbibe fluid through a porous porcelain plate under simultaneously applied almost equal pressures from 0 to 10,000 psig on both sides of the fluid-gel interface. The unidirectionally constrained volume change of the sample is measured by displacement of mercury in a steel buret. Degree of swelling is taken as the volume ratio of gel to 105° C dry clay.

In the range of pressure from 0 to 10,000 psig, the colloidal magnesium sodium montmorillonite swells from about 93 to 231 percent (volume ratio 1.93 to 3.31) depending on the composition of imbibed fluid. Aqueous 0.171N sodium chloride and magnesium chloride solutions produce 14 and 11 percent, respectively, more swelling at 1,500 than at 0 psig. Swelling in calcium chloride solution is insensitive to this pressure change. At 10,000 psig these solutions, and hydrochloric acid, produce less swelling than at 1,500 psig and, in fact, produce almost equal swellings of 130± 4 percent. It is inferred that swelling in chloride solutions at this pressure may be essentially cation-independent. Within the concentration range of 0 to 171N there appears to be little practical difference in the degree of swelling of the clay by sodium chloride and calcium chloride solutions; the swelling is a linear function of the logarithm of the salt concentration.

Comparison of d(001) spacings calculated from swelling ratios with those obtained by X-ray diffraction lead to the conclusion that the method measures crystalline swelling in contradistinction to osmotic swelling.