We discuss the chemistry of exceptionally rare phlogopite inclusions coexisting with ultramafic (peridotitic) and eclogitic minerals in kimberlite-hosted diamonds of Yakutia, Arkhangelsk, and Venezuela provinces. Phlogopite inclusions in diamonds are octahedral negative crystals following the diamond faceting in all 34 samples (including polymineralic inclusions). On this basis phlogopite inclusions have been interpreted as syngenetic and in equilibrium with the associated minerals. In ultramafic diamonds phlogopites coexist with subcalcic high-Cr2O3 pyrope and/or chromite, olivine and enstatite (dunite/harzburgite (H) paragenesis) or with clinopyroxene, enstatite, and/or olivine and pyrope (lherzolite (L) paragenesis). Ultramafic phlogopites have high Mg# [100⋅Mg/(Mg+Fe)] from 92.4 to 95.2 and Cr2O3 higher than TiO2 in H-phlogopites (1.5–2.5 wt.% versus 0.1–0.4 wt.%, respectively) but lower in L-phlogopites (0.15–0.5 wt.% versus 1.3–3.5 wt.%, respectively). Eclogitic (E) phlogopites show Mg# from 47.4 to 85.3 inclusive, and very broad ranges of TiO2 up to 12 wt.%. The primary syngenetic origin of phlogopite is indicated, besides other factors, by its compositional consistency with the associated minerals. The analyzed phlogopites are depleted in BaO (0.10–0.79 wt.%), and their F and Cl contents are highly variable reaching 1.29 and 0.49 wt.%, respectively. The latter is in line with high Cl enrichment in some unaltered kimberlites and in nanometric fluid inclusions from diamonds. The presence of syngenetic phlogopite in kimberlite-hosted diamonds provides important evidence that volatiles participated in diamond formation and that at least a part of diamonds may have been related to early stages of kimberlites formation.
Обсуждены результаты исследования структуры и свойств трехкомпонентных сплавов Ni 47−x Mn 42+x In 11 (0 ≤ x ≤ 2) после термоциклической обработки. Показано, что после многократных циклов нагрева и глубокого охлаждения наблюдаются изменение формы границ зерен и повышение микротвердости. Термоциклическая обработка не вызывает существенного изменения магнитной восприимчивости исследованных сплавов.
Humic substances are complex, organic substances occurring in natural media such as water, soils and sediments. Humic substances represent the highest pool of recent carbon on earth, and they influence climate, soil fertility and depollution. In spite of such importance, the structure and properties of humic substances are largely unknown. We studied the surfactant activity of humic acids from peat of increasing degrees of humification and sapropel, sampled in the Upa River of the Tula region. We measured critical micelle concentration (CMC) of humic acids of different ages. Our results show that CMC decreases from 1.5 g/100 ml for the less transformed sapropel, to 1.0 g/100 ml for the medium-transformed mesotrophic sphagnum peat, to 0.25 g/100 ml for the most transformed eutrophic alder peat. We also found that the limiting adsorption of humic acids from the younger sapropel, of 7.1 9 10 -6 mol/m 2 , and from sphagnum peat, of 7.6 9 10 -6 mol/m 2 , are higher than the limiting adsorption of humic acids from the older eutrophic alder peat, of 3.3 9 10 -6 mol/m 2 .
In this paper investigation results of behavior of promising superelastic alloys of Ti-Nb-Zr system in blood-vessel are presented. The possibility of their use in manufacturing of medical stents is examined. Based on analytical review of present scientific papers, four different alloys of Ti-Nb-Zr system are taken in consideration. A finite element modelling of stent behavior during delivery and opening stages is considered. These processes are done for two typical stent geometries and four alloys possessing different mechanical properties. Finite modelling results are analyzed to show the distribution of internal stresses, mechanical aspects of stent installation and effectiveness of various configurations to widen the narrowed vessel. Modeling has allowed to formulate recommendations for optimal mechanical characteristics of the superelastic alloy used for the manufacture of medical stents.
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