Isolated mixing regions and mixing enhancement in a high-viscosity laminar stirred tank

Laminar mixing in the stirred tank is widely encountered in chemical and biological industries.Isolated mixing regions(IMRs)usually exist when the fluid medium has high viscosity,which are not conducive to mixing.In this work,the researches on IMRs,enhancement of laminar mixing and the phenomenon of particle clustering within IMRs are reviewed.For most studies,the aim is to destroy IMRs and improve the chaotic mixing.To this end,the mechanism of chaotic mixing and the structure of IMRs were well investigated.The methods developed to destroy IMRs include off-centered agitation,dynamic mixing protocol,special designs of impellers,baffles,etc.In addition,the methods to characterize the shape and size of IMRs as well as mixing effect by experiments and simulations are summarized.However,IMRs are not always nuisance,and it may be necessary in some situations.Finally,the present engineering applications are summarized,and the prospect of the future application is predicted.For example,particle clustering will form in the co-existing system of chaotic mixing and IMRs,which can be used for solid–liquid separation and recovery of particles from high viscosity fluid.

Enzymatic synthesis of indigo derivatives by tuning P450 BM3 peroxygenases

Indigoids,a class of bis-indoles,have long been applied in dyeing,food,and pharmaceutical industries.Recently,interest in these‘old’molecules has been renewed in the field of organic semiconductors as functional building blocks for organic electronics due to their excellent chemical and physical properties.However,these indigo derivatives are difficult to access through chemical synthesis.In this study,we engineer cytochrome P450 BM3 from an NADPH-dependent monooxygenase to peroxygenases through directed evolution.A select number of P450 BM3 variants are used for the selective oxidation of indole derivatives to form different indigoid pigments with a spectrum of colors.Among the prepared indigoid organic photocatalysts,a majority of indigoids demonstrate a reduced band gap than indigo due to the increased light capture and improved charge separation,making them promising candidates for the development of new organic electronic devices.Thus,we present a useful enzymatic approach with broad substrate scope and cost-effectiveness by using low-cost H2O2 as a cofactor for the preparation of diversified indigoids,offering versatility in designing and manufacturing new dyestuff and electronic/sensor components.

Bochner-Martinelli Formula for Higher Spin Operators of Several R^(6) Variables

The higher spin operator of several R^(6)variables is an analogue of the■-operator in theory of several complex variables.The higher spin representation of so6(C)is⊙^(k)C_(4)and the higher spin operator D_(k) acts on⊙^(k)C_(4)-valued functions.In this paper,the authors establish the Bochner-Martinelli formula for higher spin operator Dk of several R^(6)variables.The embedding of R^(6n) into the space of complex 4n×4 matrices allows them to use two-component notation,which makes the spinor calculus on R^(6n)more concrete and explicit.A function annihilated by D_(k ) is called k-monogenic.They give the Penrose integral formula over R^(6n) and construct many k-monogenic polynomials.