Enzyme-immobilized microfluidic process reactors

Microreaction technology, which is an interdisciplinary science and engineering area, has been the focus of different fields of research in the past few years. Several microreactors have been developed. Enzymes are a type of catalyst, which are useful in the production of substance in an environmentally friendly way, and they also have high potential for analytical applications. However, not many enzymatic processes have been commercialized, because of problems in stability of the enzymes, cost, and efficiency of the reactions. Thus, there have been demands for innovation in process engineering, particularly for enzymatic reactions, and microreaction devices represent important tools for the development of enzyme processes. In this review, we summarize the recent advances of microchannel reaction technologies especially for enzyme immobilized microreactors. We discuss the manufacturing process of microreaction devices and the advantages of microreactors compared to conventional reaction devices. Fundamental techniques for enzyme immobilized microreactors and important applications of this multidisciplinary technology are also included in our topics.     

Real-time line projection for fast terahertz spectral computed tomography

We demonstrated fast terahertz spectral computed tomography by using real-time line projection of a terahertz beam. Two types of cross-sectional images of continuously rotating samples have been measured in only a few seconds. From temporal data, a peak-to-peak sinogram and cross sections have been reconstructed using a filtered backprojection algorithm. Using fast Fourier transform from temporal data, spectral cross sections of the sample have been obtained.     

Effect of uniaxial stress on ionic conductivity of 14 mol%-yttria-stabilized zirconia single crystal

In the present study, the ionic conductivity of the 14 mol%-yttria stabilized zirconia single crystal subjected to the tensile or compressive stress was examined at various temperatures. The conductivity was increased by the tensile stress and the improvement in the conductivity was higher at the lower temperature and also for the specimen with the <100> orientation. On the other hand, the conductivity was decreased by the compressive stress. The change by the compressive stress was higher at the lower temperature, but it was generally smaller than that in the tensile test. The maximum improvement achieved by applying the tensile stress was about 18% at 850 K in the present study. The present experimental results qualitatively agreed with the molecular dynamics simulations on the oxygen diffusion. The oxygen displacement in the fluorite lattice caused by the applied stress could be attributed to the change in the conductivity.     

A Concise and Versatile Synthesis of Alkaloids from Kopsia tenuis: Total Synthesis of (±)‐Lundurine A and B

A total synthesis of (±)‐lundurines A and B is described. These natural products have a unique hexacyclic skeleton which includes a cyclopropane‐fused indoline. A stereospecific construction of the pentasubstituted cyclopropane core was achieved, by radical cyclization using SmI₂, with perfect stereoselectivity. Cyclizations to give seven‐ and five‐membered heterocycles, under palladium and ruthenium catalysis, respectively, accomplished the total syntheses. The late‐stage construction of the F ring by ring‐closing metathesis enabled access to the title compounds from a spiroindoline intermediate which is a common structure of other kopsia alkaloids.     

Construction of Quaternary Stereogenic Carbon Centers through Copper‐Catalyzed Enantioselective Allylic Cross‐Coupling with Alkylboranes

A combination of an in situ generated chiral Cu^I/DTBM‐MeO‐BIPHEP catalyst system and EtOK enabled the enantioselective S_N2′‐type allylic cross‐coupling between alkylborane reagents and γ,γ‐disubstituted primary allyl chlorides with enantiocontrol at a useful level. The reaction generates a stereogenic quaternary carbon center having three sp³‐alkyl groups and a vinyl group. This protocol allowed the use of terminal alkenes as nucleophile precursors, thus representing a formal reductive allylic cross‐coupling of terminal alkenes. A reaction pathway involving addition/elimination of a neutral alkylcopper(I) species with the allyl chloride substrate is proposed.     

Ultrafast fluorescence dynamics of FMN-binding protein from Desulfovibrio vulgaris (Miyazaki F) and its site-directed mutated proteins

Ultrafast fluorescence dynamics of FMN in FMN-binding protein (FMN-bp), and its mutated proteins, W32Y and W32A, were investigated by the fluorescence up-conversion method. Fluorescence lifetimes were 167 fs (96%) and 1.5 ps (4%) in wild-type FMN-bp (WT), and 3.4 ps (23%), 18.2 ps (74%), and 96 ps (3%) at 530 nm in W32Y, and 30.1 ps in W32A. The fluorescence lifetime of W32A, in which Trp-32 was absent, was about 140 times longer than that of WT. Tyr-32 in W32Y was not so effective quencher as Trp-32 in WT. This was explained in terms of different ionization potentials of quenchers and average donor–acceptor distances in the protein.     

Photocatalytic selective oxidation of CO with O2 in the presence of H2 over highly dispersed chromium oxide on silica under visible or solar light irradiation

A highly dispersed Cr⁶⁺-oxide species on silica (Cr/SiO₂) was found to act as an efficient photocatalyst for the selective oxidation of CO into CO₂ with O₂ in the presence of H₂ under visible (λ>420 nm) or solar light irradiation at 293 K. UV-Vis, photoluminescence and FT-IR investigations revealed that the selective reactivity of the photoexcited tetrahedral Cr⁶⁺-oxide species ([Cr⁵⁺−O⁻]^*) with CO, as well as the high reactivity of the photoreduced Cr⁶⁺-oxide species (Cr⁴⁺-oxide species) with O₂ both play significant roles in this reaction.     

Second harmonic generation from multilayered hybrid polymer nanoassemblies enhanced by coupled surface plasmon resonance

We report enhanced second harmonic generation from nanostructured multilayers in combination with nonlinear optical polymer nanosheets and gold nanoparticles.     

Hydrogenation of hindered ketones catalyzed by a silica-supported compact phosphine-Rh system

A heterogeneous mono(phosphine)-Rh catalyst system silica-SMAP-Rh(OMe)(cod), where silica-SMAP stands for a caged, compact trialkylphosphine (SMAP) supported on silica gel, showed broad applicability toward the hydrogenation of hindered ketones. Doubly alpha-branched ketones such as diisopropyl ketone was hydrogenated under nearly atmospheric conditions. Di-tert-butyl ketone could be hydrogenated under more forcing conditions.