The thermal dissociation of some carbonate minerals

Detailed differential thermal studies on mixtures ofnatural carbonate minerals have confirmed the peak-temperature shifts recently reported for mixtures ofsynthetic carbonates and have established that such shifts can be attributed entirely to dilution effects. The exception, where magnesite in the presence of siderite maintains its peak position, is due simply to the fact that both minerals give similarly sized peaks at approximately the same temperature.

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Zusammenfassung Eingehende differentialthermische Untersuchungen von Gemischen natürlicher Karbonatmineralien zeigten ähnliche Spitzentemperaturverlagerungen wie kürzlich bei Gemischen von künstlichen Karbonatgemischen beobachtet wurden. Solche Verlagerungen sind ausschließlich Dilutionserscheinungen zuzuschreiben. Magnesit behielt zwar in Gegenwart von Siderit seine Spitzenpositionen, wofür jedoch der Umstand verantwortlich ist, daß beide Mineralien ähnliche und bei gleichen Temperaturen erscheinende Spitzen besitzen.

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Résumé L'étude de mélanges de carbonatesnaturels par les procédés thermiques différentiels a confirmé l'observation faite récemment d'un déplacement de la température au sommet du pic pour des mélanges de carbonatessynthétiques. On attribue ces déplacements entièrement aux effets de dilution. La magnésite en présence de sidérite constitue une exception. Dans ce cas, la position du pic reste inchangée du fait que ces deux minéraux donnent des phénomènes sensiblement identiques presque à la même température.

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Application of amorphous silicon field effect transistors in addressable liquid crystal display panels

It is shown that thin-film field effect transistors (FETs) made from amorphous (a-) silicon deposited by the glow-discharge technique have considerable potential as switching elements in addressable liquid crystal display panels. The fabrication of the elements and their characteristics with steady and pulsed applied potentials are discussed in some detail. Two important points are stressed: (i) a-Si device arrays can be produced by well-established photolithographic techniques, and (ii) satisfactory operation at applied voltages below 15VV is possible. Small experimental 7×5 transistor panels have been investigated and it is shown that with the present design up to 250-way multiplexing could be achieved. The reproducibility of FET characteristics is good and in tests so far no change has been observed after more than 10⁹ switching operations.     

Fermi surface and quasiparticle excitations of Sr2RhO4

The electronic structure of the layered 4d transition metal oxide Sr2RhO4 is investigated by angle resolved photoemission. We find well-defined quasiparticle excitations with a highly anisotropic dispersion, suggesting a quasi-two-dimensional Fermi-liquid-like ground state. Markedly different from the isostructural Sr2RuO4, only two bands with dominant Rh 4dxz,zy character contribute to the Fermi surface. A quantitative analysis of the photoemission quasiparticle band structure is in excellent agreement with bulk data. In contrast, it is found that state-of-the-art density functional calculations in the local density approximation differ significantly from the experimental findings.     

Monitoring real-time curing of epoxies in situ using single-sided NMR

Adhesively bonded joints using epoxy are widely used in aircraft and aerospace structures. Quality control and defect detection during epoxy curing in such applications is critical. We used single-sided nuclear magnetic resonance (NMR) to nondestructively probe and spatially resolve the change in the characteristic NMR relaxation time (T₂) of epoxies during curing on a substrate. Time-dependent T₂ values were fit to a Weibull function to model temporal changes in the NMR measurables. Our results demonstrate that the reduction in molecular mobility of various epoxy/curing agent mixtures occurs more rapidly at the interface than in the bulk. Further use of single-sided NMR to acquire spatially resolved T₂ data will provide a route for elucidatory epoxy curing studies. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 616–623     

Halide glasses

Halide glasses comprise a relatively uncommon class of inorganic glass systems which have heretofore been considered mainly as laboratory novelties. Serious attempts to develop these systems have generally been lacking owing to both difficulties in fabrication as well as because of the toxicity and chemical instability of some of these glasses. While halide glasses based upon beryllium fluoride and zinc chloride are well-known, the glass forming ability of ZrF₄, AlF₃, HfF₄, and more recently PbF₂ have also been demonstrated. The purpose of this review is to assess the technical and scientific importance of these glass systems, particularly with respect to advances within the past ten years.     

Shape dependence in the formation of condensed phases exhibited by disubstituted sucrose esters

We report on the self-organizing properties of sucrose esters that are di-(1',6', 1',6, and 6,6')-substituted with aliphatic chains of identical or different chain lengths and levels of saturation. For the materials possessing two saturated aliphatic chains, the compounds exhibited thermotropic lamellar smectic A phases. A remarkable new phase transition was observed for the di-octadecanoyl homologue in which one smectic A phase transformed into another with a continuous change in layer spacing, but with a discontinuous change in the correlation length. The incorporation of long cis-unsaturated chains led to increased cross-sectional areas of the chains relative to the sucrose head groups and, hence, columnar phases were observed.     

The Inequality Between Two Distributions: Applications to the Analysis of Diversity Data

A new measure called diversity difference is proposed for the inequality of a pair of distributions. The diversity difference measure satisfies eight properties of a measure of inequality. This measure is simple to calculate and provides easily interpreted results.Existing inequality measures examine the distribution of a single variable whose data are arranged in a monotonic order. The new measure can employ multiple variables and does not require each to be monotonic but can be used if the data happen to be monotonic. The pair of distributions is useful for organizational diversity data because one of the distributions represents the actual proportions of employees in any class or set of classes and the other distribution is the benchmark or anchoring distribution. Data from the measure can be displayed in diversity difference trees for quick interpretation.The diversity difference measure can be arranged to define a Lorenz curve. An example with three classes (gender, race, and age) is employed to provide examples of the measure, the resulting Lorenz curve, and the disparity ratio.