Microcellular biomorphous Al2O3 was produced by Al-vapor infiltration in pyrolyzed rattan and pine wood-derived biocarbon preforms. At 1600°C the biocarbon preforms reacted with gaseous aluminum to form Al4C3. Af...
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The final coating structure is important in terms of coating gloss and opacity, print gloss, and ink setting characteristics. Much empirical experience has moved coatings towards optimum levels, but when there is a ra...
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ISBN:
(纸本)1595101748
The final coating structure is important in terms of coating gloss and opacity, print gloss, and ink setting characteristics. Much empirical experience has moved coatings towards optimum levels, but when there is a raw material change or grade change, there is much expense in predicting the final coating structure. Many recent computer models have advanced our abilities to predict coating structure from particle packing models, but little has been done to describe the calendering operation that is known to determine coating gloss. Here, a particle level model to describe the compression of pigments to simulate the calendering operation is proposed. Particles are placed into a structure with a drainage flow field and compressed with a row of particles that represent the calender surface. The results are compared to pilot scale experiments for two pigment size distributions. The gloss increase due to calendering and the pore size distributions are well predicted before and after calendering. The modeling technique should help predict the gloss response of coating suspensions with various pigment size distributions.
We propose a new type of micro/nano fluidic mixer based on non-equilibrium electrokinetics and demonstrate its mixing capacity. We fabricate the device with two-step reactive ion etching, one for a nanochannel and one...
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We propose a new type of micro/nano fluidic mixer based on non-equilibrium electrokinetics and demonstrate its mixing capacity. We fabricate the device with two-step reactive ion etching, one for a nanochannel and one for a microchannel. Mixing is achieved by strong vortex structures formed near the micro/nano channel interface. We expect the proposed device to be beneficial in the development of micro total analysis systems, since it is simple in its design yet with minimal fabrication complications.
The coupled activated dynamics in dense mixtures of repulsive and sticky hard spheres is studied using stochastic nonlinear Langevin equation theory. The effective free energy surface, barriers, saddle point trajector...
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The coupled activated dynamics in dense mixtures of repulsive and sticky hard spheres is studied using stochastic nonlinear Langevin equation theory. The effective free energy surface, barriers, saddle point trajectories, and mean first passage times depend in a rich manner on mixture composition, (high) total volume fraction, and attractive interaction strength. In general, there are three types of saddle point trajectories or relaxation pathways: a pure sticky or pure repulsive particle displacement keeping the other species localized, and a cooperative motion involving repulsive and attractive particle displacements. The barrier for activated hopping usually increases with the ratio of sticky to repulsive particle displacement. However, at intermediate values of the displacement ratio it can attain a broad plateau value, and can even exhibit a local maximum, and hence nonmonotonic behavior, at high sticky particle mixture compositions if the attraction strength is modest. The mean first passage, or hopping, times are computed using multidimensional Kramers theory. In most cases the hopping time trends reflect the behavior of the barrier height, especially as the sticky particle attraction strengths become large. However, there are dramatic exceptions associated with cooperative repulsive and attractive particle trajectories where the barriers are high but a greatly enhanced number of such trajectories exist near the saddle point.
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