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The Iconclass browser has often been used as a standard in AI projects, but has not been used to the same extent to standardise metadata in heritage institutions. Yet with the increasing proliferation of AI, metadata standardisation is imperative. This article provides insight into the new version of the Iconclass browser and explains some common misconceptions about the tool. It makes the case for standardisation of metadata and the potential use of the Iconclass browser toward that goal.
Artificial stacking faults can be created within a well-crystallized kaolinite by intercalating and removing hydrazine. X-ray powder patterns with electron microscopy show that the created defects are ±b/3 translations with a proportion 0.30. The infrared spectrum of the treated kaolinite is not modified with respect to the starting one. On the other hand, a natural kaolinite containing defects by displacement of Al vacancies in a similar proportion shows an infrared spectrum significantly different from that of a well-crystallized kaolinite. The modification of the infrared spectra of natural disordered kaolinites is then related to the presence of defects by change of Al vacancy positions
Seven kaolins from Georgia (southeastern U.S.A.), ranging from high to low commercial grade, were characterized by X-ray powder diffraction and chemical techniques to establish that the variation in quality was caused by impurities. The Ca and Cs cation-exchange capacities (CEC) varied from 2.67 to 8.17 and from 3.29 to 8.77 meq/100g, respectively. Selective dissolution and correlation analyses strongly indicated that expandable 2:1 minerals, particularly smectite (1.2-5.9%), were responsible for most of the observed variations in Ca CEC (r = 0.85*). The external surface CEC of kaolinite ranged from 0 to 1 meq/ 100 g. The positive significant correlation (r = 0.90**) between the Ca CEC and the K-mica content (03.9%) suggested that Ca CEC may be related to the degree of mica weathering through an expandable mineral stage.
The Cs-retention capacity (0.19–1.14 meq/100 g) was closely related to Cs-measured vermiculite content (r = 0.80*), and this content plus specific surface (R = 0.93**) or mica content (R = 0.86*). The Cs retention appeared to be primarily related to the presence of interlayer wedges at mica/vermiculite XY interfaces.
Micas are described from the kaolin type Tertiary weathering crusts formed on granites and gneisses of Lower Silesia, Poland. In the weathering crust, large scale processes of transformation of micas (muscovite, biotite) take place. Weathering of micas is a gradual transformation of their structures by removal of the mobile cations Mg2+ Fe2+ Fe3+ and finally K +. Muscovite transforms into kaolinite through the intergrowths of two phases, mica and kaolinite. A degradation series, muscovite → mica/montmorillonite → montmorillonite → kaolinite also is observed. Biotite passes directly into kaolinite, but at higher concentrations of K and Al one observes the following sequence of biotite degradation: biotite → dioctahedral mica rich in Fe → dioctahedral mica poor in Fe → kaolinite. This process involves the exchange of Mg2+ and then Fe2+ of octahedral layers by Al3+ less mobile under weathering conditions. In the next stage of degradation, K + removal and kaolinite formation takes place. The micas representing different stages of this transformation, dark green, light-green, and silver-white, have been separated and investigated.
X-ray superlattice reflections, infrared spectroscopy, and chemical analyses have established that cetylpyridinium bromide (CPB) is highly ordered when adsorbed on vermiculite. The molecules, which stand at about 57° to the silicate surface, form close-packed arrays. Full surface coverage is achieved only for the most highly charged vermiculites. The packing within the arrays accounted for the superlattice observed and each adsorbed molecule had an area of 18.4 Å2 at the surface. The implications of these findings for the CPB method used in soil surface area studies are discussed.
The preventive services at the center of Braidwood Management, Inc. v. Becerra contribute to reducing inequities in life expectancy in the United States. Critical preventive are currently fully covered by insurance as preventive care under the Affordable Care Act. Reducing affordable access to such screenings and medicines is most likely to impact those with lower incomes and less education, and contribute to widening existing inequities in health outcomes.
Recent research has identified a large and growing mortality gap between those with and without college degrees. On average, individuals without college degrees are likely to die about 8.5 years earlier than those with such degrees. In recent decades, cancer death rates fell nearly two times faster among the college educated. Mortality from heart disease fell by nearly two-thirds among those with college degrees but by less than one-third for all others.
Disparities in life expectancy in the United States reflect the uneven progress against the leading causes of death among different populations. The Braidwood decision, if upheld, will raise the costs to patients for interventions that have contributed to recent gains in life expectancy. This Article analyzes the impact of Braidwood on preventive health interventions in the context of growing life expectancy gaps within the United States.
Organic matter present in clayey sediments may act as a cement between the clay particles as well as a blocking agent for the swelling of clay minerals like montmorillonite.
Removal of the organic matter is important when a clay sample is to be characterized by X-ray powder diffraction, or when it is to be separated into the composing minerals on the basis of differences in density.
Eight different methods for the removal of organic matter from a North Sea clay sample have been studied. Of all methods tried bromine oxidation was found to be the most effective.
Hydroxy-Al- and hydroxy-Mg-montmorillonite were prepared by treating dispersed Na-montmorillonite with aluminum and magnesium nitrate solutions and titrating with NaOH solutions so that the OH/Al ratio varied from zero to 3.0 and the OH/Mg ratio from zero to 2.0. External precipitation of Al and Mg hydroxides was observed when the OH/M ratios (M = metal) approached 3 and 2, respectively. From chemical analyses of the initial Na-montmorillonite and the hydroxy-metal montmorillonites, structural formulae were derived by assuming that the silicate layer compositions remained unchanged. Prior to the addition of NaOH, the average interlayer material approximated in composition to [Al(OH)2]+ and [Mg(OH)]+. With additions of NaOH the interlayer compositions moved progressively towards Al(OH)3 and Mg(OH)2. When the hydroxy interlayers approached completion, external precipitation was observed. X-ray powder diffraction data showed that the hydroxy-Mg products have less tendency to swell in ethylene glycol and water, and greater thermal stability than the hydroxy-Al products. Initially, when the average interlayer compositions were near Al(OH)2 and Mg(OH), swelling followed more nearly the normal behavior.
Kaolinites of all kinds (fine, ‘fireclay,’ ‘type IV,’ etc.), some of which do not expand or expand incompletely with the usual intercalation methods used for comparison, are expanded completely by treatment of dry (110°C) clay with dry CsCl salt, followed by contact with hydrazine for 1 day at 65°C and then with DMSO overnight at 90°C. Comparison treatments were grinding in KOAc, soaking in hydrazine, and Li-DMSO, as well as combination of these. Following the Cs-hydrazine-DMSO treatment, the 7.2 Å spacing of 1:1 dioctahedral layer silicates shifts to 11.2 Å and the 11.2 Å/(7.2 + 11.2 Å) ratio ≃1.0. The trioctahedral 1:1 layer silicates and chlorite are not expanded by the Cs-hydrazine-DMSO procedure.
The presence of Al hydroxy species in solution during the synthesis of lepidocrocite had been previously found to influence the reaction towards goethite formation. However, under certain conditions, which are not unrealistic in terms of the natural soil environment, this influence does not occur, and Al appears to substitute for Fe(III) in the lepidocrocite structure. This substitution causes the unit-cell dimensions to decrease along the “a” direction and to increase along the “b.” From the differential line broadening of X-ray powder diffraction peaks, the incorporation of Al was found to inhibit crystal growth preferentially in the b-axis direction, the hkl peaks being more broadened the higher the value of k relative to h and l. Al-substituted lepidocrocites have been suggested to occur in soils, and although they can be synthesized under conditions approaching those expected in soils, it is considered that their formation in nature is unlikely or restricted to unusual environments.
Previous applications of the method of known additions for quantitative X-ray fluorescent analysis have assumed a linear relationship between peak intensity and concentration of the element being analyzed. This assumption is true for soils or sediments containing small amounts of the element in question. In this paper, an equation is derived which takes into account both absorption and enhancement and thus is applicable to samples containing high concentrations of the element. The equation was tested by analyzing an artificial soil sample containing 60% kaolinite and 40% hematite, i.e. the sample contained 28% by weight iron. The fluorescent analysis utilizing the equation derived here resulted in an iron content of 27%. In addition, nine soils from Hawaii were analyzed by this method and the results of these analyses compared with analyses by atomic absorption. The agreement between the two methods is good. It is concluded that the method and equations proposed here provides a reliable measurement of elements in a soil sample which contains high concentrations of the elements in question.
Independence is a key concept in probability. Conceptually, we think of two events as being independent if the outcome of one event doesn’t affect the outcome of the other and vice versa. Mathematically, we say that events A and B are independent if the probability that both occur is the product of the probabilities that each occurs. More precisely, P (A ∩ B) = P (A) (P (B) in which P () denotes the probability of the given event. Alternatively, we say that A and B are independent if the conditional probability that A occurs given that B has occurred, P (A | B), satisfies P (A | B) = P (A). That is, whether or not B occurs does not affect whether or not A occurs.
X-ray diffraction analysis of mixed alkylammonium-exchanged smectite revealed segregation of different ion species into randomly ordered layers. Vermiculite, however, showed segregation into crystallites, a behavior attributed to clay inhomogeneity. Ion segregation is explained by the hydration properties of cations as well as the energy requirements of layer expansion. Quaternary ammonium ions of different size were used to exchange ethylammonium-clays, and the effectiveness, as well as steric hindrance, of cation size in ion exchange was demonstrated. Layer charge density was related to the degree of ease of large cation adsorption. Basal spacing in suspension was found to be important in determining the preference of vermiculite for certain cations, while more freely-expanding, lower layer charge smectite did not demonstrate this phenomenon.