A facile and versatile preparation of bilindiones and biladienones from tetraarylporphyrins

Bilindiones and biladienones carrying aryl groups at the meso positions were prepared using coupled oxidation reactions of iron tetraarylporphyrins in 20-63% yield.     

Regulating Higher‐Order Organization through the Synergy of Two Self‐Sorted Assemblies

The extracellular matrix (ECM) is the natural fibrous scaffold that regulates cell behavior in a hierarchical manner. By mimicking the dynamic and reciprocal interactions between ECM and cells, higher‐order molecular self‐assembly (SA), mediated through the dynamic growth of scaffold‐like nanostructures assembled by different molecular components, was developed. Designed and synthesized were two self‐sorted coumarin‐based gelators, a peptide molecule and a benzoate molecule, which self‐assemble into nanofibers and nanobelts, respectively, with different dynamic profiles. Upon the dynamic growth of the fibrous scaffold assembled from peptide gelators, nanobelts assembled from benzoate gelators transform into a layer‐by‐layer nanosheet, reaching ninefold increase in height. By using light and an enzyme, the spatial–temporal growth of the scaffold can be modified, leading to in situ height regulation of the higher‐order architecture.     

Flow-injection determination of branched-chain L-amino acids with immobilized leucine dehydrogenase

L-Leucine, L-isoleucine and L-valine are determined by passage through a column of the enzyme immobilized on polystyrene beads, at pH 11.0. The NADH produced is monitored fluorimetrically. The detection limit is 0.1 nmol of L-leucine.     

Magnetic alignment of the chiral nematic phase of a cellulose microfibril suspension

Stable suspensions of tunicate cellulose microfibrils were prepared by acid hydrolysis of the cellulosic mantles of tunicin. They formed a chiral nematic phase above a critical concentration. External magnetic fields were applied to the chiral nematic phase in two different manners to control its phase structure. (i) Static magnetic fields ranging 1-28 T were used to align the chiral nematic axis (helical axis) in the field direction. (ii) A rotating magnetic field (5 T, 10 rpm) was applied to unwind the helices and to form a nematic phase. These phenomena were interpreted in terms of the anisotropic diamagnetic susceptibility of the cellulose microfibril. The diamagnetic susceptibility of the microfibril is smaller in the direction parallel (chi( parallel)) to the fiber axis than in the direction perpendicular (chi( perpendicular)) to the fiber axis, that is, chi( parallel) < chi( perpendicular) < 0. Because the helical axis coincides with the direction normal ( perpendicular) to the fiber axis, the helical axis aligned parallel to the applied field. On the other hand, the rotating magnetic field induced the uniaxial alignment of the smallest susceptibility axis, that is, chi( parallel) in the present case, and brought about unwinding of the helices.     

Degradation of the DNA of recA mutants of Escherichia coli K-12 after irradiation with ultraviolet light. II. Further studies including a recA uvrA double mutant

Abstract— The u.v.-induced degradation of the DNA of the recA1 mutant of Escherichia coli K-12 has been further investigated. The extensive degradation was mostly prevented by an additional mutation in the uvrA gene. Furthermore, when amino acid-starved recA bacteria were irradiated and held under a condition preventing DNA replication, the DNA was degraded very little. The mode of u.v.-induced DNA degradation was investigated by comparing the time course of release of label from the acid-insoluble fraction of two growing cultures of a recA uvrA double mutant; the one was pulse-labeled with ³H-thymidine and the other was pulse-labeled and chased thereafter for 12 min. It was found that, in spite of very little degradation of the bulk of DNA. the label incorporated into the former culture was lost rapidly from the acid-insoluble fraction. while the label incorporated into the latter culture was not. It was concluded. therefore. that breakdown of the replicating point is characteristic of recA mutants and that degradation of the bulk of DNA is induced in some way by the function of the uvrA gene. Therefore, the degradation of the major part of DNA which follows the degradation of the replicating point appears to be a secondary phenomenon.     

Emulsifying effect of graft copolymer for the homopolymer

Precipitation of poly(methyl methacrylate) (PMMA) from dimethyl sulfoxide solution by addition of water as a precipitant was studied in the presence of a well-characterized graft copolymer of poly(vinyl alcohol) (PVA). The graft copolymer which had been prepared by a radiation method and freed from PMMA and PVA homopolymers had one PMMA branch whose length was nearly equal to that of the PVA backbone. Even when such an amount of water was added to PMMA solution as to cause all the PMMA to precipitate from the solution, the precipitation was prevented by the presence of relatively small amounts of the graft copolymer. With decreasing molecular weight of PMMA, the effect of protection became more pronounced. When the precipitation was prevented, the solution was transformed into a stable emulsion. The mechanism of protection against precipitation was discussed on the basis of the results obtained and electron microscopic photographs of the emulsion particles. It was concluded that the particles of the precipitated homopolymer were covered by a monolayer of the graft copolymer, resulting in prevention of coagulation.     

Analysis of Nitrification in Agricultural Soil and Improvement of Nitrogen Circulation with Autotrophic Ammonia-Oxidizing Bacteria

Accumulations of inorganic nitrogen (NH₄ ⁺, NO₂ ^?, and NO₃ ^?) were analyzed to evaluate the nitrogen circulation activity in 76 agricultural soils. Accumulation of NH₄ ⁺ was observed, and the reaction of NH₄ ⁺?→?NO₂ ^? appeared to be slower than that of NO₂ ^??→?NO₃ ^? in agricultural soil. Two autotrophic and five heterotrophic ammonia-oxidizing bacteria (AOB) were isolated and identified from the soils, and the ammonia-oxidizing activities of the autotrophic AOB were 1.0?×?10³–1.0?×?10⁶ times higher than those of heterotrophic AOB. The relationship between AOB number, soil bacterial number, and ammonia-oxidizing activity was investigated with 30 agricultural soils. The ratio of autotrophic AOB number was 0.00032–0.26 % of the total soil bacterial number. The soil samples rich in autotrophic AOB (>1.0?×?10⁴ cells/g soil) had a high nitrogen circulation activity, and additionally, the nitrogen circulation in the agricultural soil was improved by controlling the autotrophic AOBs.