High-pressure fluidized bed coating utilizing supercritical carbon dioxide

Various particles with sizes between 100 and 200 μm were encapsulated with waxes commonly used in technical coating applications. For this, a homogeneous mixture of molten paraffin and supercritical carbon dioxide was prepared in an autoclave and injected into the high-pressure fluidized bed through a nozzle from the bottom. Due to the different conditions in the mixing autoclave and the fluidized bed, the paraffin precipitated in the vicinity of the nozzle and adhered to the solid particles. A complete, thin, uniform, and solvent-free coating was produced. The use of two paraffins with different alkane compositions resulted in dissimilar spreads on glass beads due to their different glass transition temperatures. A smaller pressure drop across the nozzle led to more uniform and even coatings. Glass beads, ceramic spheres, potassium chloride, and lactose showed similar coating results, whereas different morphologies were observed with a plastic material, characterized by a rougher surface and a lower surface energy. The high quality of the coating was confirmed by standard dissolution tests with coated potassium chloride crystals and lactose agglomerates.     

Probabilistic Marching Cubes

In this paper we revisit the computation and visualization of equivalents to isocontours in uncertain scalar fields. We model uncertainty by discrete random fields and, in contrast to previous methods, also take arbitrary spatial correlations into account. Starting with joint distributions of the random variables associated to the sample locations, we compute level crossing probabilities for cells of the sample grid. This corresponds to computing the probabilities that the well‐known symmetry‐reduced marching cubes cases occur in random field realizations. For Gaussian random fields, only marginal density functions that correspond to the vertices of the considered cell need to be integrated. We compute the integrals for each cell in the sample grid using a Monte Carlo method. The probabilistic ansatz does not suffer from degenerate cases that usually require case distinctions and solutions of ill‐conditioned problems. Applications in 2D and 3D, both to synthetic and real data from ensemble simulations in climate research, illustrate the influence of spatial correlations on the spatial distribution of uncertain isocontours.     

Fluxoid pinning by vanadium carbide precipitates in superconducting vanadium

Vanadium carbide precipitates were formed in pure, annealed vanadium foils by the introduction of carbon in the specimens. Thin, disk-shaped precipitates resulted with mean diameters in the range 100–2600 Å and with number densities from 3 × 10¹⁵ to 4 × 10¹⁷ particles/cm³. The macroscopic, pinning-force density for magnetic fluxoids was measured at temperatures from 2 to 5 K and for magnetic fields from 0 to H _c2(T). Peak pinning-force densities in the range of 3 × 10 to 3 × 10⁶ dyn/cm³ for T=0K were realized in the 30 specimens studied. The pinning force density was found to obey a scaling law for specimens meeting certain requirements with respect to precipitate particle size and number density. These requirements correlate with the temperature-dependent, superconducting coherence length (T). Many specimens obeyed the scaling law at temperatures T < T _c except near T _c, where (T) is large in comparison with the precipitate size.Part of this work was supported by the Applied Research Laboratory of The Pennsylvania State University, under contract with the U.S. Naval Sea Systems Command.