Multiphase imaging of freezing particle suspensions by confocal microscopy

Ice-templating is a well-established processing route for porous ceramics. Because of the structure/properties relationships, it is essential to better understand and control the solidification microstructures. Ice-templating is based on the segregation and concentration of particles by growing ice crystals. What we understand so far of the process is based on either observations by optical or X-ray imaging techniques, or on the characterization of ice-templated materials. However, in situ observations at particle-scale are still missing. Here we show that confocal microscopy can provide multiphase imaging of ice growth and the segregation and organization of particles. We illustrate the benefits of our approach with the observation of particles and pore ice in the frozen structure, the dynamic evolution of the freeze front morphology, and the impact of PVA addition on the solidification microstructures. These results prove in particular the importance of controlling both the temperature gradient and the growth rate during ice-templating.Comment: 20 pages, 9 figure

Liquidity and Arbitrage in Options Markets: A SurvivalAnalysis Approach

This paper examines the determinants of the time it takes for an index options market to return to no arbitrage values after put-call parity deviations, using intraday transactions data from the French index options market. We employ survival analysis to characterize how limits to arbitrage influence the expected duration of arbitrage deviations. After controlling for conventional limits to arbitrage, we show that liquidity-linked variables are associated with a faster reversion of arbitrage profits. The introduction of an ETF also affects the survival rates of deviations but this impact essentially stems from the reduction in the level of potential arbitrage profits.Limits to arbitrage, liquidity, survival analysis, index options, ETFs