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Infrared and Mössbauer spectroscopy show that the extent of the reduction of nontronite is dependent on the chemical composition of the nontronite and on the nature of the reducing agent. Hydrazine reversibly reduces about 10% of the iron in all of the nontronites studied irrespective of composition and it is suggested that the resulting ferrous iron occurs only in distorted octahedral sites. Similar conclusions are reached for the dithionite reduction of the nontronites containing little tetrahedral iron, but for those with more than one in eight silicons replaced by iron, changes brought about by dithionite treatment are irreversible due to dissolution of appreciable quantities of iron. Results from both spectroscopic techniques suggest that iron in tetrahedral sites is preferentially dissolved and that up to 80% of the structural iron can be reduced.
Evidence is presented for the formation in these extensively reduced nontronites of a small amount of a mica-like phase resembling celadonite or glauconite, and, as dithionite is used for the pretreatment of soils, the implication of this observation is briefly discussed.
The use of deuterated hydrazine as a reducing agent has enabled the nontronite absorption band near 850 cm-1 to be assigned to a Si-O (apical) stretching vibration, which is inactive in the infrared for perfect hexagonal symmetry, but which is activated by distortions in the tetrahedral layer.
The mechanism of boron uptake by clays, especially illitic clays, and the factors which control such uptake have long been debated issues. In an attempt to answer some of the questions of the controversy, three illites were treated in solutions containing boron. In the study, boron concentration, salinity, temperature, and time were varied independently over rather wide ranges.
For the illites studied, irreversible uptake of boron was increased by increasing boron concentration, salt concentration, temperature, and time of treatment. The amount of boron which was fixed also varied with the type of illite treated. The amount of fixation was controlled primarily by the specific surface area of the clay and also by the crystallinity, K content, and/or amount of mixed-layer material (“frayed-edge” development?), and apparently was independent of the original boron content of the clay.
A two-step mechanism is proposed for boron fixation by illite, consisting of rapid chemical adsorption of the tetrahedral B(OH)4− anion at the “frayed-edge” of the illite flake followed by much slower diffusion of boron into the tetrahedral part of the structure.
Several new salt intercalation complexes of halloysite have been prepared and characterized using X-ray powder diffraction techniques taking into account both the position and the shape of the d001 peaks. The amount of intercalated ion in some fully complexed halloysites has been directly determined using conventional analytical techniques. The results show that less than half of the theoretical amount of salt is intercalated into the clay; the amount of salt depending on its nature and, where hydrolyzable ions are present, on the pH. Infrared spectra taken of some complexes give an indication of the nature of the interaction within interlayer space and elsewhere. The interactions are weak and are either dipolar attractions or hydrogen bonds. The ions which show the greatest tendency to intercalate with halloysite are water structure-breaking cations or hydrogen-bonding anions.
Solubility diagrams defined by log [Al3+] and log [H4SiO4] are given for hydrous alumina or aluminum silicate minerals which appear in bauxite, kaolin and pyrophyllite-diapore deposits. They are constructed based on thermodynamic data of relevant reactions both at the room temperature and at elevated temperatures.
An aqueous solution reacts to a mineral, in this case K-feldspar, and, by dissolving it, becomes saturated with respect to a certain mineral. This mineral begins to be precipitated and the solution changes its composition as a result of the precipitation as well as further dissolution of the original mineral. Then, it attains saturation with respect to another mineral, which is precipitated thereafter. Thus, different minerals are precipitated in turn.
The sequences of precipitation of minerals can be shown on the diagrams under different conditions. A sequence, aluminum hydroxide → kaolinite or pyrophyllite → silica mineral plus kaolinite or pyrophyllite is expected in a weakly acid solution. In contrast, a sequence, silica mineral → silica mineral plus kaolinite or pyrophyllite is expected in a strongly acid solution. The possibility of application of the sequence of precipitation thus expected to alteration zoning is also discussed.
The basal spacings of long chain n-alkanol complexes of nontronite saturated with Li+, K+ Mg2+, Ca2+, Sr2+ and Ba2+ were measured for temperatures increasing from −70°C up to 130°C. With rising temperatures the complexes rearrange from a low temperature form into a high temperature form.
In the low temperature form the alkyl chains of the alkanol molecules form bilayers with their chain axes perpendicular to the silicate layers. The chains may not be in all cases in the planar all trans conformation but in special ‘kink’-conformations.
The transition into the high temperature form is explained by cooperative transition from a form with a low number of ‘jogs’ to one with a high number of ‘jogs’ and ‘kinks’.
Jesus' response to the Syrophoenician woman in Mark 7.27 is sometimes seen as sexist, racist, or abusive. The force of his response depends in part on the diminutive form κυναριον, which is often dismissed as a faded diminutive that lacks true force. But a statistical, semantic, and contextual analysis of the word indicates that it does, in fact, have diminutive force in Mark 7:27. Because of this, the pejorative force found in direct insults employing the word ‘dog’ is lacking in Jesus' response. In addition to failing to recognise the diminutive force of κυναριον, interpreters sometimes assume a social context in which Jews routinely referred to Gentiles as dogs. Finally, the analogy that Jesus makes is often read allegorically, assuming that ‘children’ and ‘dogs’ have direct counterparts in ‘Jews’ and ‘Gentiles’. These assumptions are found to be dubious. The point of Jesus' analogy is about the proper order of events: children eat before the puppies; Jews receive the benefits of his ministry before Gentiles. The Syrophoenician woman outwits Jesus by arguing that the puppies may eat simultaneously with the children. The interpretive upshot is that Jesus' saying is unlikely to be misogynistic or abusive, but simply asserts Jewish priority, a priority that admits of exceptions and change.
Three samples of bluish chromium-bearing dickite and chromium-bearing kaolinite were examined by X-ray powder diffraction, chemical analysis, electron microprobe, optical, and infrared techniques to determine whether chromium is part of the mineral structure or present in an impurity phase. Two of the samples studied contain a single dominant chromium-bearing phase (either dickite or kaolinite); the third contains equal proportions of both minerals. The optical absorption and infrared spectra are consistent with the presence of octahedrally coordinated chromium. The range of Cr3+-Al3+ substitution is rather limited: up to 0.06 atoms per unit cell. The electron microprobe study revealed the presence of very rare, minute grains of chromite, as well as a uniform distribution of chromium in dickite and kaolinite, indicating that chromium occupies octahedral sites in the structure of these minerals.
I discuss a certain kind of emotionally charged negative reaction to defences of non-monogamous love, which I call collective-identity reactions. Expanding on work by Audrey Yap and Jonathan Ichikawa, who consider defensive reactions grounded in individual identity, I argue that collective-identity reactions are characteristically associated with claims about who we are, and motivated by a sense that the relevant we is in some way under threat. Looking into which we might be threatened by defences of non-monogamy, and why, reveals that this apparently personal subject matter is in fact entangled with global political issues like capitalism and American cultural imperialism. I conclude with some thoughts about ameliorative strategies for situations structurally similar to this one.
Morphological changes occurring in naturally weathered micas in seven residual soils from Ontario were studied. Splitting, exfoliation of the (100) planes, surface coats, filling of spaces with soil material as well as cracking and crumbling of (001) surfaces were the main morphological changes found to be taking place during natural weathering of mica particles. The significance of the observed feature in relation to the general theory of mica weathering is discussed.
The electron spin resonance (ESR) spectra of varying quantities of vanadyl ion (VO2+) adsorbed on hydrated hectorite indicated that hydrolysis of VO2+ was promoted at low levels of adsorption. The hydrolyzed product was adsorbed on the clay surfaces, with a ligand environment that was partially aqueous and partially hydroxide in nature. Greater amounts of VO2+ adsorbed on wetted hectorite obscured the ESR spectrum of the strongly adsorbed hydrolysis product with a solutionlike spectrum. An approximately 50% reduction in rotational mobility of VO2+ relative to solution was indicated by the linewidth of this spectrum. Loss in mobility occurred with reduction of the interlamellar spacing until, under strongly dehydrating conditions, the VO(H2O)52+ ions became aligned with the V=O bond axis normal to the plane of the clay platelets.
A 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.
Recurrent reports of analyses of X-ray diffraction data from regularly alternating and nearly regularly alternating structures like rectorite provide opportunity for a descriptive discussion of their nature. MacEwan-transform-based analyses have uniformly shown higher incidence of unlike adjacent layers than would be expected from random distribution.
The continuous Fourier transforms for pairs of 2: 1 layer silicate structures evaluated normal to the layers, provide a family of similar curves that are differently stretched out in reciprocal space for different assumed intervals between the two members of a pair.
For each exactly alternating example the relative amplitudes of the ordered reciprocal nodes distinguish the instances for which fixed interlayer populations are Na+ from those for which they are K+.
For sequences not exactly alternating scattering maxima are displaced from exact incremental positions in conformity with the Hendricks and Teller mixing functions, but relative intensities of adjacent observations still distinguish the alkali identities.
Biotite was altered by boiling in 0.2 M A1C13 solution, and the products were examined by X-ray powder and single-crystal diffraction, chemical analysis and thermogravimetry. The altered material is a 14 Å clay mineral with hydroxy-Al interlayers. It has a stacking sequence characteristic of vermiculite and its silicate layers are similar in chemical composition to trioctahedral vermiculite. The results of extracting the interlayer material with sodium citrate solution, X-ray examinations after heating and thermogravimetry show that the interlayer material is composed of Al associated with OH and H2O. The chemistry and kinetics of the alteration reaction and the orientational between the altered and original biotites are also discussed.
In light of a recent surge of interest in time across a range of disciplines, a case has been made that New Testament studies has experienced a “temporal turn.” This claim raises an important question about how one understands the relation of recent developments to earlier, long-held debates about time among New Testament scholars. This question is answered here by revisiting the “salvation history” debate between Oscar Cullmann and Rudolf Bultmann, with the help of Paul Ricoeur’s analysis in Time and Narrative and in the context of recent trends in work on “temporalities.” This article argues that, although in many respects recent work on time offers fresh language to describe the kinds of time at stake for New Testament scholarship, it is also true that attending to the earlier debates shows how parts of the temporal turn are in fact a return to questions long considered.
Ethylenediamine (EDA) is adsorbed from aqueous solution on Na-, K- and Li-montmorillonite as the monoprotonated cation (EDAH+) through an ion-exchange process. On washing with distilled water the second amine function is protonated—probably through dissociation of water near the clay surface—and simultaneously formed alkali hydroxide is removed.
In air-dried clay films, prepared from unwashed suspensions, EDA is retained mainly through hydrogen-bonding with water co-ordinated to the exchangeable cation.
EDA adsorbed from the vapour phase is retained through co-ordination, either direct or indirect (i.e. through a ‘water-bridge’), depending on the hydration properties of the exchangeable cation. Indirect coordination increases the stability of the amino-clay complex against atmospheric humidity and heating in vacuum in the order K+ < Na+ < Li+.
Upon heating co-ordinated EDA is almost completely desorbed, whereas EDAH+ and EDAH22+ decompose above 160°C to form NH4+.