Engineering characteristics of liquid–liquid microflow and its advantages in chemical reactions.

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The Beckmann rearrangement of cyclohexanone oxime in oleum as a fast exothermic reaction model is carried out in an adiabatic multiphase microchemical system. A severe coalescene is observed due to the high viscosity of the rearrangement mixture, which decreases the reaction rate and selectivity. Gas agitation is introduced into the microsystem to enhance the reaction by reducing the coalescene and providing an evaporation space to carry away reaction heat. The effects of gas agitation on dispersion performance and mass-transfer rate have been investigated. The acid droplets diameter ranges from about 44 to 20 mm, decreasing with the increase of the gas flow rate. The overall volume masstransfer coefficient in the microsystem ranges from 0.16 to 0.74 s 21 , 1.5-3.8 times larger than that without gas agitation. The reaction performance is evaluated under different conditions and better conversion and selectivity are obtained.

Modern nanotechnologies bring humanity to a new age, and advanced methods for preparing functional nanocrystals are cornerstones. A considerable variety of nanomaterials has been created over the past decades, but few were prepared on the macro scale, even fewer making it to the stage of industrial production. The gap between academic research and engineering production is expected to be filled by flow chemistry technology, which relies on microreactors. Microreaction devices and technologies for synthesizing different kinds of nanocrystals are discussed from an engineering point of view. The advantages of microreactors, the important features of flow chemistry systems, and methods to apply them in the syntheses of salt, oxide, metal, alloy, and quantum dot nanomaterials are summarized. To further exhibit the scaling‐up of nanocrystal synthesis, recent reports on using microreactors with gram per hour and larger production rates are highlighted. Finally, an industrial example for preparing 10 tons of CaCO3 nanoparticles per day is introduced, which shows the great potential for flow chemistry processes to transfer lab research to industry.

The objective of this research was to create a Mandarin closed-set sentence recognition test based on the English pediatric speech intelligibility (PSI) test (Jerger & Jerger, 1984 ) for evaluation of speech perception in children as young as three years of age. Developmentally normal children (N = 93), 3-6 years of age, were administered the Mandarin PSI (MPSI) via a computer-controlled protocol. Perfect performance was observed for all children in quiet and at +10 and +5 dB signal-to-noise ratios (SNRs). Significant age and developmental trends were seen for the more difficult SNRs, 0 dB, -5 dB, and -10 dB, with 75% of 5-6 year olds reaching the most difficult SNR. Children who reached each of the more difficult SNRs, regardless of age, exhibited the same pattern of performance on all easier conditions, indicating that the final SNR achieved, rather than percent correct scores, may be a better descriptor of performance. The MPSI comprises part of a hierarchical assessment battery for pediatric speech perception for evaluation of intervention alternatives for Mandarin-speaking children with hearing impairment.

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Despite the popularity of the lattice-Boltzmann method (LBM) in simulating multiphase flows, a general approach for modeling dilute species in multiphase systems is still missing. In this report we propose to modify the collision operator of the solute by introducing a modified redistribution scheme. This operator is based on local fluid variables and keeps the parallelism inherent to LBM. After deriving macroscopic transport equations, an analytical equation of state of the solute is exhibited and the method is proven constituting a unified framework to simulate arbitrary solute distribution between phases, including single-phase soluble compounds, amphiphilic species with a partition coefficient, and surface-adsorbed compounds.

Searching for new additives to enhance the alkylation of isobutane and butene in H 2 SO 4 has attracted the interest of academic as well as industrial researchers since the process was introduced to produce high-quality oil product on a large scale. This research focused on alkylation of isobutane and butene with caprolactam as an additive in H 2 SO 4 . With the new additive of caprolactam, the selectivity of C8 was obviously improved due to the improved solubility of isobutane in H 2 SO 4 and the decreased acidity. Different additive amounts of caprolactam were tested, showing that 1.0 wt % is optimal and that the selectivity of alkane C8 can be improved from nearly 80% to 88%. The effects of stirring speed, reaction temperature, acid to hydrocarbon volume ratio, isobutane to butene molar ratio, reaction time, and variety of olefin were also studied carefully and respectively. Extended duration runs were practiced, which has demonstrated that the system was stable. This new additive has potential to be applied in large-scale industrial processes to improve the quality of alkylation.