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Excimer Laser-Induced CVD of Carbon Encapsulated Cobalt Nanoparticles
Fajgar, Radek ; Maryško, Miroslav ; Dřínek, Vladislav ; Kupčík, Jaroslav ; Šubrt, Jan
Decomposition of acetylene / Co(CO)(3)(NO)mixtures induced by excimer ArF laser pulses is an efficient technique for preparation of amorphous cobalt nanoparticles encapsulated in carbon. Vacuum heating up to 900 degrees C leads to crystallization the metal core. The cobalt core crystallizes in a face-centered cubic (beta) form as revealed by X-ray and electron diffraction techniques and carbon affords graphite outer part. Properties of the Co(core) - carbon(shell)nanocomposites were examined by spectroscopy and microscopy techniques. Magnetization studies revealed paramagnetic behavior of the as-prepared amorphous deposit and superparamagnetic behavior of the annealed samples.
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Gas Hold-up and Volumetric Mass Transfer Coefficient of Various Impeller Types in Gas-Liquid Dispersion with Higher Viscosity
Zedníková, Mária ; Linek, V. ; Moucha, T.
In a vessel with inner diameter 0.29 m supplied by one, two or three impellers on a common shaft, there were measured transport characteristics (gas hold-up and volumetric mass transfer coefficient) in dependence on power consumption. As an impeller there was used the pitched blade impeller pumping the liquid either upwards or downwards. Air was used as a gas phase and 3% solution of Sokrat 44 as a liquid phase. The solution behaves as a newton liquid with viscosity 12.9mPa.s. Volumetric mass transfer coefficient was measured by dynamic pressure method. Gas hold-up and kLa were presented in dependence on power consumption and on gas superficial velocity. Results are compared with the data of given impeller types obtained in low viscous solutions and with the data of other impeller types.
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Transportní charakteristiky různých vícemíchadlových konfigurací v míchané disperzi kapalina-plyn s vyšší viskositou
Moucha, T. ; Zedníková, Mária ; Linek, V.
Mixing intensity, gas hold-up and volumetric mass transfer coefficient of various multiple-impeller configurations are measured in a vessel of inner diameter 0.29 m equipped with three impellers on a common shaft. Five types of impellers are used. Distilled water with 3 vol.% Sokrat 44 is used as a liquid phase with Newtonian behaviour and viscosity 12.9 mPa.s. Air is used as gas phase. Mixing intensity was measured using tracer experiment and Dynamic Pressure Method was used for the measurement of volumetric mass transfer coefficient. Transport characteristics are presented for individual impeller configurations as functions of power consumption and superficial gas velocity. The impellers are compared each other and with transport characteristics for non-viscous solutions measured previously.
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dGO disociace pevných heterodimerů
Malijevská, I. ; Sedláková, Zuzana
Solid – liquid equilibria of two binary systems were measured. Both systems, propanoic acid – trifluoroacetic acid and acetic acid – trichloroacetic acid, form a compound in the solid phase. Activity coefficients in the liquid phase were calculated and thermochemical data of the given compounds dissociation determined.
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