저작근 근전도에 관한 정상교합자와 ii급 부정교합자의 비교 연구

Phyllosilicates, and among them clay minerals, are of great interest not only for the scientific community but also for their potential applications in many novel and advanced areas. However, the correct application of these minerals requires a thorough knowledge of their crystal chemical properties. This chapter provides crystal chemical and structural details related to phyllosilicates and describes the fundamental features leading to their different behaviour in different natural or technical processes, as also detailed in other chapters of this book. Phyllosilicates, described in this chapter, are minerals of the (i) kaolin-serpentine group (e.g. kaolinite, dickite, nacrite, halloysite, hisingerite, lizardite, antigorite, chrysotile, amesite, carlosturanite, greenalite); (ii) talc and pyrophyllite group (e.g. pyrophyllite, ferripyrophyllite); (iii) mica group, with particular focus to illite; (iv) smectite group (e.g. montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite); (v) vermiculite group; (vi) chlorite group; (vii) some 2:1 layer silicates involving a discontinuous octahedral sheet and a modulated tetrahedral sheet such as kalifersite, palygorskite and sepiolite; (viii) allophane and imogolite and (ix) mixed layer structures with particular focus on illite-smectite.

Structure and Mineralogy of Clay Minerals

From the above table it is inferred that 3 dependent variables Perceived Organization Support, Organization Commitment and Turnover Intention are considered to identify the significant relationship with the analyzing variable age. All the three variables Perceived Organization Support, Organization Commitment and Turnover Intention have significant relationship with the analyzing variable age at (.05) level of significance.

With the age....

カナダ鉱山冶金学会 (Canadian Institute of Mining and Metallurgy) の憲章と定款

https://hal-upec-upem.archives-ouvertes.fr/hal-00693555/document

Iron (III)-silica interactions in aqueous solution: Insights from X-ray absorption fine structure spectroscopy

Prograde evolution of illite/smectite occurring in an unusually-thick (8000 m) sequence of Mesozoic-Cenozoic sediments in the Basque-Cantabrian Basin, Spain, has been studied using XRD and TEM/AEM. The sediments, which are only slightly tilted, cover the range from smectite to illite, and the most deeply buried ones are unique in that they span the range from diagenesis through low-grade metamorphism (anchizone), with no apparent overprinting due to tectonic deformation. Pelites are absent from the shallow section, but smectite occurs in marls as high-charge, K-dominant and low-charge, K-poor anastomosing arrays of layers. At intermediate depths, authigenic clay is identified largely as Rl I/S, coexisting with packets of R≫3 I/S (nearly pure illite), where illite-like and smectitelike layers can be identified by contrast in TEM images, which is consistent with XRD data. The authigenic clay of the deepest samples consists of illite with no or almost no expandable layers, which occurred as packets with layers largely subparallel to bedding, K-deficient composition in comparison with muscovite, lMd-like SAED patterns, and 100 A mean packet thickness. There is no evidence of deformation stress-induced, non-bedding-parallel clays in the deepest samples. Detrital micas with either a phengiterich or a phengite-poor composition range dominate the phyllosilicate fraction of all the samples. Detrital micas show no changes over the diagenesis/metamorphism range and appear to have behaved as if isolated from authigenic clays. Authigenic clays occur as bedding-subparallel packets that evolved during passive burial metamorphism through dissolution/crystallization of less-evolved clays. Where illite-like and smectite-like layers can be identified, TEM images imply a discontinuous series in which packets of Rl I/S (50% I) transform to packets of nearly-pure illite, that is, an Ostwald-step-rule-like sequence. Such immature illite remains unmodified with further burial, and is apparently the potential predecessor of stress-induced, highly-evolved mica of higher-grade, tectonically-deformed pelites.

Evolution of Illite/Smectite from Early Diagenesis Through Incipient Metamorphism in Sediments of the Basque-Cantabrian Basin

The white mica crystallinity index has been analyzed as a function of the following parameters: 1) the domain size, 2) lattice distortion, and 3) the presence of other phyllosilicates overlapping the 10 A XRD peak, particularly I/S mixed-layer (2) is determined by the variance method suggested by Wilson (1963) and subtracted from the experimental XRD profile The remanent peak width is compared with the statistical values obtained from direct measurements of (1) on HRTEM images The relation between 10 A and 5 A peak widths was used for the evaluation of (3) When R3 I/S mixed-layers are absent, the progressive decrease of the illite crystallinity index is a consequence of a parallel improvement in both quantity of defects and crystallite size

A comparative XRD and TEM study of the physical meaning of the white mica "crystallinity" index

Three types of glaucony grains were identified in the late Eocene (~35.5–34.1 Ma) sediments from Ocean Drilling Program (ODP) Hole 696B in the northwestern Weddell Sea (Antarctica). The grains are K2O-rich (~7 wt%) and formed by smectite-poor interstratified ~10 A glauconite-smectite with flaky/rosette-shaped surface nanostructures. Two glaucony types reflect an evolved (types 1 and 2 glaucony; less mature to mature) stage and long term glauconitization, attesting to the glaucony grains being formed in situ, whereas the third type (type 3 glaucony) shows evidences of alteration and reworking from nearby areas. Conditions for the glaucony authigenesis occurred in an open-shelf environment deeper than 50 m, under sub-oxic conditions near the sediment-water interface. These environmental conditions were triggered by low sedimentation rates and recurrent winnowing action by bottom-currents, leading to stratigraphic condensation. The condensed glaucony-bearing section provides an overview of continuous sea-level rise conditions pre-dating the onset of Antarctic glaciation during the Eocene-Oligocene transition. Sediment burial, drop of O2 levels, and ongoing reducing (postoxic to sulphidic) conditions at Hole 696B, resulting in iron-sulphide precipitation, were a key limiting factor for the glauconitization by sequestration of Fe2+.

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Glaucony authigenesis, maturity and alteration in the Weddell Sea: An indicator of paleoenvironmental conditions before the onset of Antarctic glaciation

In spite of decades of research on the subject, the crystal structure of illite is still poorly understood. The purpose of this study was to address this problem by investigating the nature of the interlayer content in illite IMt-2 from Silver Hill, Montana, using analytical transmission electron microscopy (ATEM), thermogravimetry (TG), and X-ray powder diffraction (XRPD) analyses. The ATEM data, together with literature and TG results, yielded the formula K0.70a0.01(H2O)0.42 (Al1.53Fe2+0.06Fe3+0.19Mg0.28)Σ−2.06(Si3.44Al0.56)O10(OH)2 or, assuming the presence of H3O+, K0.69Na0.01(H3O)+0.28(Al1.47Fe2+0.06Fe3+0.19Mg0.28)Σ−1.99(Si3.40Al0.60)O10(OH)2. The first formula indicates surplus interlayer and octahedral species, whereas the second shows no excess. The XRPD data were refined by Rietveld techniques, down to an Rp factor of 10.48–13.8%. The mineral composition consists largely of illite-2M1, illite-1M, and minor quartz. Although the refinement accuracy is limited by the intrinsic poor quality diffraction of the illites, the partially refined model is consistent with the chemical composition; in particular, attempts to introduce octahedral cations in excess of 2 were fruitless. All the results support the simple structural model, by which the illite structure strictly corresponds to a dioctahedral mica with H3O+ replacing K. As a consequence, the crystalchemical formula of illites should be calculated on the basis of six tetrahedral plus octahedral cations.

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The role of h3o+ in the crystal structure of illite

Analytical electron microscopy of representative smectites from soils and sediments revealed that K was present in significant proportions. It was the major interlayer cation in soils from pelitic rocks, continental and marine sediments, independent of their diagenetic grade. Sodium was predominant only in soils from basic rock. Fluvial sediments contained smectites with both kinds of interlayer compositions. The octahedral composition of each sample ranged widely, covering various fields of dioctahedral smectites. The most important trend was the substitution of Al by Fe and Mg; the chemistry of each smectite particle was determined by the parent mineral from which it formed. The real interlayer composition has important implications for the diagenetic smectite–illite transformation. When considering a typical K content, the smectite–illite reaction, with chlorite and quartz as subproducts, needs only 0.21 K atoms. For more K-rich compositions, a reaction is possible without an external supply of K.

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Fernando Nieto

Papers

Evolution of Illite/Smectite from Early Diagenesis Through Incipient Metamorphism in Sediments of the Basque-Cantabrian Basin

A comparative XRD and TEM study of the physical meaning of the white mica "crystallinity" index

Glaucony authigenesis, maturity and alteration in the Weddell Sea: An indicator of paleoenvironmental conditions before the onset of Antarctic glaciation

The role of h3o+ in the crystal structure of illite

Chemical composition of smectites formed in clastic sediments. Implications for the smectite—illite transformation