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An enzymatic method using L-phenylalanine ammonia-lyase (EC 4.3.1.5) for the rapid conversion of trans-cinnamic acid to L-phenylalanine has been investigated. With Rhodotorula glutinis, enzyme activity as high as 0.3 U/ml of culture broth was obtained. The enzyme activity was kept stable for a relatively long time during cultivation by the addition of L-isoleucine. Optimization of the parameters of the conversion reaction resulted in accumulation of 18 mg of Lphenylalanine per ml of reaction mixture. The conversion yield from transcinnamic acid was about 70%. The method may provide a rapid and practical way to produce L-phenylalanine useful as an essential amino acid. L-Phenylalaninle ammonia-lyase (PAL; EC 4.3.1.5), an enzyme found in a variety of plants,

We investigated the electronic structure and lattice dynamics of double perovskite NdBaMn2O6 single crystals through spectroscopic ellipsometry and Raman scattering spectroscopy. The optical absorption band centered at approximately 0.88 eV was assigned to on-site d–d transitions in Mn, whereas the optical feature at approximately 4.10 eV was assigned to charge-transfer transitions between the 2p state of O and 3d state of Mn. Analysis of the temperature dependence of the d-d transition indicated anomalies at 290 and 235 K. The activated phonon mode, which appeared at approximately 440 cm−1 alongside with the enhancement of the 270 cm−1 phonon mode, coupled strongly to the metal–insulator transition at 290 K, which was associated with a charge/orbital ordering. Moreover, the MnO6 octahedral breathing mode at 610 cm−1 exhibited softening at a temperature lower than 235 K (temperature of the antiferromagnetic phase transition), which revealed the strong coupling between the lattice and magnetic degrees of freedom. The spin–phonon coupling constant obtained was λ = 2.5 cm−1. These findings highlight the importance of charge–orbital–spin interactions in establishing NdBaMn2O6 phases with novel properties.

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The gigantic decrease of resistance by an applied magnetic field, which is often referred to as colossal magnetoresistance (CMR) 1-9 , has been an attracting phenomenon in strongly correlated electron systems. The discovery of CMR in manganese oxide compounds has developed the science of strong coupling among charge, orbital, and spin degrees of freedom. CMR is also attracting scientists from the viewpoint of possible applications to sensors, memories, and so on. However, no application using CMR effect has been achieved so far, partly because the CMR materials which satisfy all of the required conditions for the application, namely, high operating temperature, low operating magnetic field, and sharp resistive change, have not been discovered. Here we report a resistance change of more than two-orders of magnitude at a magnetic field lower than 2 T near 300 K in an A-site ordered NdBaMn 2 O 6 crystal. When temperature and a magnetic field sweep from insulating (metallic) phase to metallic (insulating) phase, the insulating (metallic) conduction changes to the metallic (insulating) conduction within 1 K and 0.5 T, respectively. The CMR is ascribed to the melting of the charge ordering. The entropy change which is estimated from the B-T phase diagram is smaller than what is expected for the charge and orbital ordering.The suppression of the entropy change is attributable to the loss of the short range ferromagnetic fluctuation of Mn spin moments, which an important key of the high temperature and low magnetic field CMR effect. arXiv:1811.07596v1 [cond-mat.str-el]

Enzymatic production of dihydroxyacetone (DHA) was studied by immobilization of the whole cells of acetic acid bacteria capable of oxidizing glycerol to DHA. Acetobacter xylinum A-9 cells immobilized in a polyacrylamide gel were selected as the most favorable enzyme preparation. The enzymatic properties of immobilized cells converting glycerol to DHA were investigated and compared with those of intact cells. The optimum pH for the immobilized cells was broad (4.0 to 5.5), whereas the intact cells had a narrow pH optimum at 5.5. The thermal stability of the immobilized cells was somewhat higher than that of the intact cells. Apparent Km values for glycerol with both intact and immobilized cells were about equal, 6.3 x 10-2 to 6.5 x 10-2 M. The complete conversion of glycerol to DHA was achieved within 40 h under optimum conditions, and pure crystalline DHA was readily isolated from the reaction mixture with over 80% yield.