bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Interpretation of Classically Quantified Sentences: A Set‐Theoretic Approach
Authors: Politzer Guy , Van der Henst Jean‐Baptiste , Delle Luche Claire , Noveck Ira A. 
Published: September 2006

AbstractWe present a set‐theoretic model of the mental representation of classically quantified sentences (All P are Q, Some P are Q, Some P are not Q, and No P are Q). We take inclusion, exclusion, and their negations to be primitive concepts. We show that although these sentences are known to have a diagrammatic expression (in the form of the Gergonne circles) that constitutes a semantic representation, these concepts can also be expressed syntactically in the form of algebraic formulas. We hypothesized that the quantified sentences have an abstract underlying representation common to the formulas and their associated sets of diagrams (models). We derived 9 predictions (3 semantic, 2 pragmatic, and 4 mixed) regarding people's assessment of how well each of the 5 diagrams expresses the meaning of each of the quantified sentences. We report the results from 3 experiments using Gergonne's (1817) circles or an adaptation of Leibniz (1903/1988) lines as external representations and show them to support the predictions.
Geometric Analysis and Characteristics of a Three-Fixed-Pivoted Multi-Phalanx Robotic Finger
Authors: Luo Z , Dai J S 
Published: September 2006

This paper investigates the kinematic structure of robotic fingers, presents a linkage type of multi-phalanx (multi-joint) robotic fingers, and delivers geometric analysis. The new type of robotic fingers is driven by a three-pivoted linkage constituting a mechanism of two degrees of freedom. On the basis of mechanism decomposition with decoupled kinematics, this paper produces the closed-form kinematic equations for modelling the linkage. Decoupling the linkage into a loop linkage and a function generator of a four-bar linkage, the linkage geometric property and workspace are explored and a stiffness map is produced. The paper further develops the linkage Jacobian matrix and investigates the workspace characteristics.
The Nature of Kenya Vermiculite and its Aluminum Hydroxide Complexes
Authors: Brydon J. E. , Turner R. C. 
Published: September 2006

AbstractA specimen of Kenya vermiculite contained no mica or chlorite layers either as separate phases or as components of an interstratifled structure. Dehydroxylation occurred in two stages, at 550° and 850°C, with approximately equal amounts of hydroxyl liberated in each stage. Al-saturated Kenya vermiculite showed low temperature dehydration characteristics similar to those of the natural Mg-saturated specimen, but the DTA, TGA and oscillating-heating X-ray diffraction patterns showed that the three stage dehydration process was not as clear-cut with the Al-saturated specimen.As with montmorillonite, when small amounts of aluminum were precipitated by the addition of Ca(OH)2 in the presence of vermiculite, the Al(OH)x, was taken up and held indefinitely by the clay, the ion product (Al)(OH)3 in solution was maintained at 10-33∙0 and no gibbsite was formed with time. With large amounts, 800 and 1600 me Al(OH)x per 100g vermiculite, the hydroxide was held initially in the interlayer space, but gibbsite was eventually formed as (Al)(OH)3 approached the solubility product of gibbsite. Unlike montmorillonite, the vermiculite specimens retained an appreciable amount of the interlayer hydroxide and did not regain the original C.E.C. values as gibbsite was formed.Al-vermiculite which was repeatedly suspended in AlCl3 with (Al)(OH)3 maintained at a value less than 10-33∙8 liberated 435 me Mg, took up 208 me Al as an interlayer hydroxide and caused a reduction in C.E.C. from 130 to 28 me per 100g clay. With vermiculite an appreciable amount of the interlayer Al(OH)x was stable with respect to gibbsite whereas with montmorillonite it was not.
Alkylammonium Decomposition on Montmorillonite Surfaces in an Inert Atmosphere
Authors: Durand B. , Pelet R. , Fripiat J. J. 
Published: September 2006

AbstractA study of the thermal transformation of alkylammonium cations adsorbed on the surface of a montmorillonite in various conditions of hydration has been carried out. The experimental conditions were: inert atmosphere, temperatures below 250°C and time periods up to 270 days. The reactions observed are mainly transalkylations, for which a mechanism of acid catalysis is proposed. A high degree of dissociation of the water remaining on the surface of the clay is required and is attained for an optimal, and rather low, water content of the clay.
Thermodynamics of the Exchange of n-Alkylammonium Ions on Na-Montmorillonite
Authors: Vansant E. F. , Uytterhoeven J. B. 
Published: September 2006

AbstractA thermodynamic study has been made of the ion exchange equilibria of the n-alkylammonium ions in sodium montmorillonite. Exchange isotherms of ammonium, methylammonium, ethylammonium, propylammonium and butylammonium with sodium montmorillonite were determined at 4°, 25° and 55°C. From these data the changes in free energy, enthalpy and entropy for the exchange reactions were calculated. In the temperature region used in this work, no enthalpy change was observed. Thus the exchange was only controlled by entropy effects. The thermodynamic excess functions were calculated from the surface activity coefficients. The affinity of the organic ions for the clay increases with chain length. It is shown that this increase can not be ascribed to van der Waals forces, but must be due to the combined effect of variations in electrostatic interactions with the clay lattice and of the hydration state.
Electron Optical Observations on Marblehead Illite
Authors: Güven Necip 
Published: September 2006

AbstractElectron optical observations on Marblehead illite showed the presence of twinned aggregates of lath-shaped crystallites. The selected area diffraction patterns of these aggregates indicate a strict orientational relationship between them.Original twinned mica flakes display all possible stages of the transformation of these micas into lath-shaped illites, where the a and b dimensions of layers do not show any noticeable changes, but c-dimension becomes shortened in the illites. The transformation seems to involve parting along (110) of the micas, subsequent H2O and OH inclusion in the structure and other possible chemical changes resulting from the hydration. The morphology and the size of lath-shaped crystallites displaying (001) and (110) forms seem to be responsible for the excess of water and K-deficiency in the Marblehead illite compared to the micas.Individual illite laths commonly have a length 0·1–4 μ, a width of 0·01–0·1 μ and a thickness varying between 10 and 50 Å.
X-Ray Diffraction and Electron Optical Studies on Smectite and α -Cristobalite Associations
Authors: Güven Necip , Grim Ralph E. 
Published: September 2006

AbstractAlteration products of volcanic materials from various localities in Wyoming, U.S.A., Italy, Yugoslavia and Mozambique are mainly smectites and cristobalites with small amounts of kaolinite.Smectite and cristobalite form separate and intergrown aggregates of microcristallinity. X-ray diffraction studies show that the silica is α-cristobalite with a noticeable stacking disorder. Small aggregates of optically pure α-cristobalite, which were separated by an appropriate mixture of bromo-form and carbon tetrachloride, are shown to contain a noticeable amount of smectite on Debye-Scherrer diffraction photographs for the samples from Italy and Wyoming, U.S.A.Transmission electron micrographs and selected area electron diffraction photographs show, in addition to smectite and α-cristobalite aggregates, the presence of idiomorph single crystals of kaolinite.
Selective Sorption and Fixation of Cations by Clay Minerals: A Review
Authors: Sawhney B. L. 
Published: September 2006

AbstractInvestigations concerning selective sorption and fixation of K and similar cations by clay minerals and soil clays and the mechanisms of these reactions are reviewed. In particular, recent observations on selective sorption of these ions in dilute solutions by weathered micas and vermiculite in relation to the interlayer structures are discussed in detail. Also, implications of the resistance to weathering of small mica particles to cation selectivity by soils are described. Despite the increased understanding of sorption and fixation reactions, the following aspects remain unclear.First, the mechanism of the collapse of alternate layers in vermiculite on K or Cs sorption has not been unequivocally established. Second, factors that impart stability to the central core of mica particles so that K extraction becomes progressively difficult are not known. Third, inability of Ca or Mg ions to expand interlayers of Cs-saturated vermiculite in contrast to K-saturated vermiculite is not completely understood.
Dodecylammonium-Mica Complexes—II Characterization of the Reaction Products
Authors: Mackintosh E. E. , Lewis D. G. , Greenland D. J. 
Published: September 2006

AbstractInterlayer potassium was removed from a wide range of mice minerals by treatment with dilute solutions of n-dodecylammonium chloride. On subsequent reaction with the appropriate metal methoxide, the Na+ or Ca2+ form of the altered mica was produced. The properties of the original and sodium saturated samples were compared to assess the changes in water content, charge density and chemical composition (particularly ferrous iron) which resulted from the displacement of potassium.Calculation of structural formulae was not attempted since it was established that for the altered samples accurate distinction could not be made between adsorbed and structural water. Changes in layer charge are thus expressed on the basis of samples ignited to 1000°C. Charge losses of up to 76 me/100 g were recorded for biotites, smaller charges were noted for phlogopites and no loss was observed for the two muscovites examined.Oxidation of ferrous iron occurred for all trioctahedral samples, the greatest oxidation occurring in the samples initially high in iron. There was no consistent relationship between the amount of iron oxidized and the loss of layer charge.All altered samples contained greater amounts of H2O+ than the original materials suggesting that protonation of structural oxygens occurred during, or following, removal of potassium.It is concluded that the alteration of micas by reaction with organic cations is a complex process, differing in detail for different micas, and following a similar path to alteration by reaction with inorganic salts.
The Occurrence of Sepiolite and Attapulgite on the Southern High Plains
Authors: McLean S. A. , Allen B. L. , Craig J. R. 
Published: September 2006

AbstractSepiolite and attapulgite have been found to be common, sometimes the major, clay minerals in calcareous lacustrine deposits on the southern High Plains in West Texas and eastern New Mexico. Deflation debris derived from the basins and calcareous soils developed in the debris and in the lacustrine deposits also often contain either or both minerals. Dolomite is the carbonate commonly associated with sepiolite and calcite has a similar relationship to attapulgite in the lacustrine deposits. Pedogenic formation of sepiolite and attapulgite appears unlikely in the area studied since an association with lacustrine materials was made in a very high percentage of the occurrences.Sepiolite was found to be highly concentrated in the < 0•2μ fraction. A similar, but less pronounced, distribution was noted for attapulgite. The studies suggest that the minerals have developed authigenically in alkaline lacustrine environments during periods of desiccation. Such an environment, interrupted by more humid periods, would have obtained during dry Pleistocene intervals. Volcanic ash is suggested as the source of the essential silica. The Mg concentration would appear to determine whether sepiolite-dolomite or attapulgite-calcite were formed.
Selectivity Effect of Cesium on Clay Size Weathered Mica; Transmission Electron Microscopy Studies
Authors: Gal M. , Rich C. I. 
Published: September 2006

AbstractThe use of electron diffraction contrast to detect local concentrations of interlayer cations in mica-vermiculites was examined. Cs and Mg, because of their contrasting atomic scattering amplitudes for electrons, were chosen as exchange ions for Ca. Cs was absorbed to the near exclusion of Mg by the clays from the three soils and by weathered clay-size muscovite and phlogopite. The presence of Cs in addition to the other interlayer cations, K and Ca, caused bending and perhaps splitting of the mica-verrmculite layers. Extinction bend contours were common in Cs-treatea specimens but not those Ca-treated. After freeze-drying of specimens of Cs-Ca Nason clay, differential destruction by the electron beam of the central core in clay-size vermiculite containing hydrated Ca ions may indicate the edge location of Cs.
Transmission Electron Microscopy of Fine-Grained Phyllosilicates in Ultra-Thin Rock Sections
Authors: Phakey P. P. , Curtis C. D. , Oertel G. 
Published: September 2006

AbstractA method is described for preparing electron-transparent sections of fine-grained argillaceous rocks suitable for making transmission micrographs. A sediment and a slate are used as examples. Sections perpendicular to bedding or cleavage yield diffraction patterns with clearly defined 00l reflections. These allow immediate identification of 7, 10 and 14 Å structures. The combination of detailed textural information with structural identification of individual phyllosilicate particles affords a powerful method for the investigation of late diagenetic and early metamorphic changes in sediments.
Irreversible Collapse of Montmorillonite
Authors: Ertem Gözen 
Published: September 2006

AbstractA number of variable charge montmorillonites were prepared. One portion of each sample was extracted with ammonium chloride, while a second portion was first saturated with calcium chloride, washed, and then extracted with ammonium chloride. In both cases, the number of cations displaced by ammonium chloride was determined. The number of calcium ions displaced from Ca-saturated samples was higher than the sum of the number of lithium and calcium ions displaced from Li, Ca-mixed samples. The differences, increasing towards Li-rich end of the series are assumed to be due to protons liberated from the reaction of lithium ions with either structural hydroxyl groups or residual water molecules, as has been shown by other investigators. Supplementary X-ray and i.r. data lend support to this idea.
Extinction Bend Contours in Electron Microscopy of Clay-Size Mica-Vermiculites
Authors: Gal M. , Rich C. I. 
Published: September 2006

AbstractExtinction bend contours, observed in Cs-treated mica-vermiculites by transmission electron microscopy, give information on the morphology and crystal orientation and continuity in individual particles of clay size. Interlayer Cs apparently stretches that part of the silicate sheet in closest proximity and when exchange by Cs is incomplete, warping of the particle occurs. Warping favors the appearance of bend contours in transmission electron microscopic images of the particles. These contours terminate at crystal boundaries within a particle. A specimen tilting stage is useful in bringing the contours into view and in “exploring” individual particles.
Montmorillonite Complexes With Dioxane, Morpholine, And Piperidine: Mechanisms of Formation
Authors: Brindley G. W. , Tsunashima Atsumu 
Published: September 2006

AbstractThe absorption of dioxane, morpholine and piperidine from dilute aqueous solutions by Li-, Ca-, and Cu-montmorillonite is measured by means of a differential refractometer. This instrument measures small differences in the refractive indices of two liquids and provides a useful method for determining the amount of organic material removed from solution by the clay. Corrections are required for the effect of desorbed cations on the differential refraction measurements. Neutral molecules are absorbed in amounts related to the exchange capacity of the clay probably by cation-dipole interactions. The results are consistent with the formation of complexes Li+-fi and R-Ca2+-R for the three organic materials used; Cu2+ ions behave like Ca2+ ions for dioxane, but form $\mathop >\limits_R^R C{u^{2 + }} - R$ complexes with morpholine and piperidine. Under acid conditions, morpholine and piperidine form organic cations RH+ which take part in cation exchange reactions and which are dominant at pH below about 5. Neutral molecule absorption also occurs by virtue of the presence of RH+ ions on the clay which form RH+-R complexes (hemisalt formation). When this last mechanism of absorption occurs, the total absorption is approximately twice that when a cation-dipole reaction or cation exchange alone operates. One-dimensional Fourier 00l syntheses of complexes in equilibrium with aqueous organic solutions indicate that water molecules are associated with the clay-organic complexes to the extent of about 5H2O/unit cell.
Adsorption of Ethylenediamine (EDA) on Montmorillonite Saturated with Different Cations—II. Hydrogen- and Ethylenediammonium-Montmorillonite: Protonation and Hydrogen Bonding
Authors: Cloos P. , Laura R. D. 
Published: September 2006

AbstractThe form under which ethylenediamine (EDA) is adsorbed from aqueous solution by hydrogen- and ethylenediammonium-montmorillonite was studied as a function of the amount of amine present in the system.EDA added to the acid clay in quantities lower than or equal to the cation exchange capacity (C.E.C.) was exclusively adsorbed as ethylenediammonium (EDAH22+) ion. On further addition of diamine the pH of the suspension rose to alkaline values and the monoprotonated species (EDAH+) was the main charge balancing cation.Evaporating at room temperature “EDA-H-montmorillonite-H2O” or “EDA-EDAH2-mont- morillonite-H2O” systems containing 300 me EDA/100 g clay did not cause loss of nitrogen, but degassing under high vacuum (10−5 mm Hg) did. Nevertheless, excess EDA molecules with respect to the C.E.C. were retained on the clay surface, at the expense of water molecules, through strong asymmetrical hydrogen bonds between their NH2 groups and the NH3+ groups of EDAH+ ions. On heating up to 160°C under vacuum the nitrogen content decreased further, but still remained at a level significantly higher than the C.E.C. value, all NH3+ groups remaining involved in strong hydrogen bonding. It is suggested that a “condensation” process takes place, implying evolution of EDA molecules and giving rise to “polymeric” associations between protonated and unprotonated diamine.Washing the clay suspensions with distilled water did not completely remove excess EDA either, as a consequence of the equilibrium existing between the ionic species in solution (EDAH22+ and EDAH+) and on the clay surface. It seems that these species were preferentially adsorbed as “trimeric” associations in which two out of four NH3+ groups are hydrogen bonded to NH2 groups.After heating at 200°C, nitrogen retained on the clay surface was mainly in the form of NH4+ ions. Ammonium formation was enhanced by the presence of excess EDA and was considerably faster than in montmorillonite systems containing EDA coordinated to Cu2+ ions.
The Chlorite Series of Flagstaff Hill Area, California: A Preliminary Investigation
Authors: Post J. L. , Plummer C. C. 
Published: September 2006

AbstractThe results of X-ray diffraction, DTA, i.r. spectroscopy, and chemical tests are presented for some chlorites typical of the Flagstaff Hill area. The area is notable for the large variety of chlorite types occurring in considerable quantities. Chlorite, in this area, is found as veins, as pseudomorphs, and as individual crystals. Textures vary from massive, fine-grained aggregates to books which are more than 20 mm in width. Crystals more than 5 mm in size occur in parallel groupings at rock interfaces. Judging from 45 chlorite samples studied, sheridanite is most abundant; clinochlore and ripidolite are common. Penninite and its Cr-chlorite equivalent are less abundant. The parent rock is an irregularly shaped ultramafic body surrounded by low-grade schists and located very close to a granodiorite stock. The original ultramafic rocks have been highly altered by metamorphism and metosomatism into assemblages comprised mainly of serpentine, talc, hornblende, and chlorite with relics of olivine, pyroxene, and other less abundant original minerals. Much of the exposed rock is essentially monomineralic, mostly consisting of various polytypes of serpentine. Preliminary investigation indicates that the area merits much more study because of the opportunity for readily observing the various chlorite types and determining their genesis, alteration sequences and weathering characteristics. The area, being easily accessible, could also serve as an adequate source for samples to be used as reference standards.
Comparative Chemical Composition of Sediment Interstitial Waters
Authors: Parashiva Murthy A. S. , Ferrell R. E. 
Published: September 2006

AbstractInterstitial waters squeezed from modem sediments with a 100 psi pressure at laboratory temperature (23°C) are depleted in K and Ca and enriched in Mg when compared to the solutions obtained at in situ temperature (28°C). The changes are especially pronounced when the samples are refrigerated during transport back to the laboratory. The magnitude of the variation in chemical composition was dependent on the element being analyzed as well as the sediment used. The maximum observed depletion in the laboratory was about 12% per degree difference in temperature for potassium. Element ratios in the solutions were affected most seriously. The Mg/Ca and Na/K ratios increased 51 and 60% respectively.A water extraction method using sediment to water ratios of 1:2, 1:5, and 1:10 was compared with the pressure method. The total composition of the pore fluids obtained by squeezing is greater than expected, corresponding to a sediment to water ratio less than 1:5. The artificially squeezed sediments are yielding pore fluids which are more concentrated than the “in-place” solutions.The water extraction method yields results which are in agreement with the behavior predicted by the Donnan Principle. It is suggested that the values obtained by successive dilution analyses can be extrapolated to measured moisture contents and used to determine the elemental composition and element ratios in interstitial pore fluids.
Clay Mineral Synthesis — III Rapid Hydrothermal Crystallization of An Aluminian Smectite
Authors: Granquist W. T. , Hoffman G. W. , Boteler R. C. 
Published: September 2006

AbstractAn aluminian smectite with about one Al3+/Si4+ replacement per unit cell was batch- synthesized on a large scale (100-gal autoclave) at 3 00°C and 1240 psig with reaction times of several hours rather than days. This rapid crystallization was related to the use of NH4+ as the charge-balancing cation and to partial F/OH substitution. The short synthesis time prompted a study of continuous crystallization. Either of two techniques, flow through a stirred autoclave and through a multi-staged reactor column, produced crystalline product; neither gave the crystallinity of the batch process.