Based on previous work studying complex microreactors, it was desired to further improve the mixing efficiency by varying the mixing unit design for fast liquid—liquid reactions. Different flow regimes were studied, including slug flow, parallel flow, and drop flow. The two-phase hydrolysis of 4-nitrophenyl acetate in sodium hydroxide solution was used to evaluate the overall volumetric mass transfer coefficients (K org a) as a function of the average rate of energy dissipation (ε) for each microreactor design and all flow regimes. The liquid—liquid systems investigated used n-butanol or toluene as the organic phase solvent and a 0.5-M NaOH aqueous solution. The use of surfactant was also investigated with the toluene—water system. All microreactor geometry designs were based on contraction—expansion repeating units with asymmetric obstacles to aid the breakup of slugs and desynchronize the recombination of split streams. The investigated designs were chosen to avoid the formation of the parallel flow regime, contrary to curvature-based mixing-unit designs. The microreactor design can then be optimized to reduce the ε required to reach drop flow, since K org a has been found to be constant at equal ε for a given solvent system in this flow regime, regardless of the reactor selection. Additionally, the “3/7th” scaleup rule was applied and confirmed with the LL-Triangle mixer. It was found that, for low interfacial-tension systems (i.e., n-butanol—water), the onset of drop flow occurred at a lower ε for the LL-Triangle mixer when compared with the Sickle or LL-Rhombus mixers.
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Mechanical mixing of molecular crystals
A green route to co-crystals and coordination networks
Abstract
Supramolecular reactions between crystalline materials can be exploited to prepare both hydrogen bonded co-crystals and coordination networks. Mechanical mixing of molecular crystals as well as kneading provide an alternative, solvent-free, route to novel materials hence these methods represent a green route to supramolecular solid-state chemistry.
Balan, R. M. and Zamfirescu, I. M. , Strong Approximation for Mixing Sequences with Infinite Variance, Electr. Comm. Probab. , 11 (2006), 11–23. MR 2006m :60034
Role of rice and added wheat protein in the mixing properties of different rice flours
(A preliminary study)
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. Microwave dielectric behavior of wet soil, Part II, Dielectric mixing models, IEEE Trans. Geosci. Remote Sensing , Vol. GE-23, 1985, pp. 35–46. El-Rayes M. A. Microwave dielectric
Abstract
Fuel mix monitoring is important for optimum performance of vehicles. A variety of techniques used to monitor fuel mixes have not come into widespread use due to practical difficulties. Gamma attenuation has been found to be a potential technique for petroleum based fuel mix monitoring with certain limitations.
., Wrigley, C.W., Appels, R. 1994. The contribution to mixing properties of 1D HMW glutenin subunits expressed in a bacterial system. In: Henry, J.R., Ronalds, J.A. (eds), Improvement of Cereal Quality by Genetic Engineering. Marcel Dekker, New York, USA, pp
