Zur Beeinflussung der Umwandlung von γ‐Fe₂O₃ in α‐Fe₂O₃ durch Alkali‐, speziell K⁺‐Zusätze

Abstract

Durch Differentialthermoanalyse und röntgenographische Untersuchungen wird an Hand einer Fe2O3‐Reihe mit abgestuftem KOH‐Zusatz festgestellt, daß sich die Umwandlung von γ‐Fe2O3 in α‐Fe2O3 mit steigendem K‐‐Gehalt beträchtlich nach höheren Temperaturen verschiebt. Dafür wird besonders bei größeren K+‐Gehalten nicht eine Stabilisierung der γ‐Phase durch K+‐Einbau, sondern die Tendenz des Systems zur Bildung der Verbindung K2O · 6 Fe2O3 verantwortlich gemacht. Die DTA‐Untersuchungen werden auf eine analoge Oxidreihe mit NaOH Zusatz ausgedehnt.

Taxonomy and Phylogeny of the Dileptid Ciliate Genus Paradileptus (Protista: Ciliophora), With a Brief Review and Redescriptions of Two Species Isolated From a Wetland in Northern China

“…Vd 'ačný and Foissner (2012) reviewed the descriptions of the remaining eight species and concluded that only one, P. elephantinus, is valid. However, based on our present findings and following a reassessment of the historical studies, we consider four species to be valid, namely, P. flagellatus (Rousselet, 1890) Wenrich, 1929 [basionym: Amphileptus flagellatus Rousselet, 1890]; P. elephantinus (Šveç, 1897(Šveç, ) Kahl, 1931 [see section "Results" for synonyms]; P. conicus Wenrich, 1929 [see section "Results" for synonyms]; and P. moniliger (Ehrenberg, 1835) Vd'ačný & Foissner, 2012[synonyms: P. ovalis Huber-Pestalozzi, 1945P. estensis Canella, 1951;P.…”

“…The type species was originally reported by Rousselet (1890) as Amphileptus flagellatus, but Wenrich (1929) established a new genus (Paradileptus) for A. flagellatus based on the broad peristomial field with its raised rim and the spiral arrangement of the proboscis. It is noteworthy that A. moniliger, reported by Ehrenberg (1835), was the first species discovered in this genus, but was overlooked in subsequent revisions (Wenrich, 1929;FIGURE 7 | Bayesian inference (BI) tree inferred from ITS-5.8S rDNA sequences focusing on the subclass Rhynchostomatia (26 rhynchostomatian and five spathiid taxa). Numbers near branches show the posterior probabilities from BI and bootstrap values from maximum likelihood (ML) analyses.…”

“…Ten nominal species of Paradileptus have been reported but only four are valid, namely, P. flagellatus (Rousselet, 1890) Wenrich, 1929, P. elephantinus (Šveç, 1897) Kahl, 1931, P. conicus Wenrich, 1929, andP. moniliger (Ehrenberg, 1835) Vd 'ačný & Foissner, 2012. Among these, only P. conicus has been studied using observations in vivo, protargol staining, and electron microscopy, and documented using photomicrographs (Foissner et al, 1995(Foissner et al, , 1999.…”

Thermal stability and reactivity in oxygen of potassium ferrites with spinel structure

“…5 indicates that the presence of potassium has increased the activation energy and the oxidation temperature of these spinel phases, especially for low substitution extents. Lichtner et al [17] mentioned that the oxidation temperature of potas- …”