Formation of a Network Structure in the Gaseous Reduction of Magnetite Doped with Alumina

Reduction of un-doped magnetite is developed topochemically with the formation of a dense iron shell. However, the reduction of alumina-doped magnetite to wüstite proceeds with the formation of a network-like structure which consists of criss-crossed horizontal and vertical plates of wüstite. Reduction of magnetite includes the conversion of Fe³⁺ to Fe²⁺ and the movement of iron cations from the tetrahedral sites on the {400} and {220} planes of magnetite to the octahedral sites on the {200} planes of wüstite. Alumina has a negligibly small solubility in wüstite. In the reduction of magnetite doped with Al₂O₃, rejected Al³⁺ cations from wüstite diffuse to the magnetite–hercynite solid solution. Enrichment of the Fe₃O₄–FeAl₂O₄ solution with alumina in the vicinity of the reduction interface restricts the growth of {220} planes of wüstite and nucleation of {220} planes adjusted to the existing planes, preventing the merging of wüstite plates during the reduction process. Reduction of magnetite from the magnetite–hercynite solid solution practically stops when the Al³⁺ content at the interface approaches the solubility limit. Wüstite in the separated plates is reduced further to iron.     

Gas temperature measurements in weakly ionized glow discharges with filtered Rayleigh scattering

We report the first gas temperature measurements in plasmas to our knowledge obtained by filtered Rayleigh scattering (FRS). A narrow-linewidth Ti:sapphire laser is used as the illumination source, and a mercury filter provides strong suppression of elastic background. We perform measurements in weakly ionized glow discharges in pure argon and in an argon-plus-1%-nitrogen mixture. Where possible, we verify the FRS technique by comparing filtered measurements with unfiltered measurements. We present point measurements of axial temperature with uncertainties of less than 5%. We use a planar scheme to obtain radial temperature profiles with uncertainties of 10%.     

Three-dimensional imaging of microspheres with confocal and conventional polarization microscopes

We experimentally studied the three-dimensional imaging of the microspheres by using confocal and conventional scanning polarization microscopes. Because of the field amplitude averaging effect of the confocal system, the polarization of the detected signals is mainly parallel to the initial polarization. As a result, the signal intensity from the microspheres in the confocal polarization microscope with a crossed analyzer was found to be weaker than that in the conventional system. Based on a vector approach that takes the polarization into account and on the image formations of the two systems, theoretical expressions are given that agree well with the experimental results.     

Bile secretion in dogs after intravenous administration of glucose

The effect of drop infusions of 10% glucose solution for parenteral nutrition, in a dose of 2 g/kg, on bile secretion was studied in experiments on dogs with chronic gallbladder-duodenal fistulas. It was demonstrated that the infusion of hypertonic glucose solution inhibits bile production quantitatively and qualitatively.