Reactivity of finely dispersed iron (III) oxides and oxide hydroxides in solid-state reactions

The kinetics of the reaction of-Fe₂O₃ (hematite) with K₂CO₃ was studied at 600–800 °C for hematite samples prepared in different ways. The results demonstrated that the hematite reactivity is not a simple function of the specific surface area (or particle size), but depends significantly on the sample preparation history, especially at lower reaction temperature. The effect of low-temperature sintering on the hematite reactivity is discussed.

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Zusammenfassung Die Kinetik der Reaktion unterschiedlich präparierter-Fe₂O₃- (Hämatit-) Proben mit K₂CO₃ bei 600–800 °C wurde untersucht. Die Ergebnisse zeigen, dass die Reaktivität des Hämatits keine einfache Funktion der spezifischen Oberfläche (bzw. Teilchengrösse) ist, sondern deutlich von der Vorgeschichte der Probe, insbesondere bei tieferer Temperatur, abhängt. Der Einfluss des Tieftemperatursinterns auf die Reaktivität des Hämatits wird diskutiert.

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600–800° (-₂₃) . , ( ), , , «» . .

     

The nonstationary ideal and the other

Under Martin's Maximum every -ideal on is a subset of an ideal Rudin-Keisler reducible to a finite Fubini power of the nonstationary ideal restricted to a positive set.

     

Applications of the ergodic iteration theorem

I prove several natural preservation theorems for the countable support iteration. This solves a question of Ros?anowski regarding the preservation of localization properties and greatly simplifies the proofs in the area (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Strongly almost disjoint functions

Two total functionsf, g fromω ₁ toω are called strongly almost disjoint if {α<ω ₁:f(α)=g(α)} is finite. We show that it is consistent with ZFC to have families of pairwise strongly almost disjoint functions of arbitrary prescribed size.     

More σ-ideals with the Laczkovich-Komjáth property

I consider the Laczkovich-Komjáth property of sigma-ideals concerning countable sequences of analytic sets and I prove or disprove it for various sigma-ideals. Connections with definable forcing appear.     

Four and more

We isolate several large classes of definable proper forcings and show how they include many partial orderings used in practice.     

A method for estimation of transport properties of ZSM-5 zeolite

A method for a quick testing of transport properties of samples of a zeolite catalyst has been developed. The method is based on the application of gas-phase chromatography, where the tested sample is used as the stationary phase. Cyclopentene, cyclohexane, and 1,3,5-trimethylcyclohexane were used as the testing molecules. A retention indexes for samples comparison were introduced. The method is sensitive even to small changes in the zeolite structures caused by binding agents and/or alkali metals.     

Keeping additivity of the null ideal small

We shall show that various statements are consistent with additivity of the null ideal equal to for example, ``all branchless trees of size are special', (S) conjecture and ``there are only five cofinal types of directed posets of size '.