X-ray magnetic circular dichroism and photoemission study of the diluted ferromagnetic semiconductor Zn1−x_{1-x}Crx_xTe

We have performed x-ray magnetic circular dichroism (XMCD) and valence-band photoemission studies of the diluted ferromagnetic semiconductor Zn$_{1-x}$Cr$_x$Te. XMCD signals due to ferromagnetism were observed at the Cr 2p absorption edge. Comparison with atomic multiplet calculations suggests that the magnetically active component of the Cr ion was divalent under the tetrahedral crystal field with tetragonal distortion along the crystalline a-, b-, and c-axes. In the valence-band spectra, spectral weight near the Fermi level was strongly suppressed, suggesting the importance of Jahn-Teller effect and the strong Coulomb interaction between the Cr 3d electrons

Regioselective glucosidation of trans-resveratrol in Escherichia coli expressing glucosyltransferase from Phytolacca americana

A glucosyltransferase (GT) of Phytolacca americana (PaGT3) was expressed in Escherichia coli and purified for the synthesis of two O-β-glucoside products of trans-resveratrol. The reaction was moderately regioselective with a ratio of 4′-O-β-glucoside: 3-O-β-glucoside at 10:3. We used not only the purified enzyme but also the E. coli cells containing the PaGT3 gene for the synthesis of glycoconjugates. E. coli cell cultures also have other advantages, such as a shorter incubation time compared with cultured plant cells, no need for the addition of exogenous glucosyl donor compounds such as UDP-glucose, and almost complete conversion of the aglycone to the glucoside products. Furthermore, a homology model of PaGT3 and mutagenesis studies suggested that His-20 would be a catalytically important residue

Impurity emission characteristics of long pulse discharges in Large Helical Device

Line spectra from intrinsic impurity ions have been monitored during the three kinds of long-pulse discharges (ICH, ECH, NBI). Constant emission from the iron impurity shows no preferential accumulation of iron ion during the long-pulse operations. Stable Doppler ion temperature has been also measured from Fe XX, C V and C III spectra

Room-temperature thermally induced relaxation effect in a two-dimensional cyano-bridged Cu-Mo bimetal assembly and thermodynamic analysis of the relaxation process

We observed a photo-switching effect in [CuII(1,4,8,11-tetraazacyclodecane)]2[MoIV(CN)8]·10H2O by irradiation with 410-nm light around room temperature using infrared spectroscopy. This photo-switching is caused by the photo-induced charge transfer from MoIV to CuII. The photo-induced phase thermally relaxed to the initial phase with a half-life time of 2.7 × 101, 6.9 × 101, and 1.7 × 102 s at 293, 283, and 273 K, respectively. The relaxation process was analyzed using Hauser's equation, k = k0exp[−(Ea + Ea*γ) / kBT], where k is the rate constant of relaxation, k0 is the frequency factor, Ea is the activation energy, Ea* is the additional activation energy due to the cooperativity, and γ is the fraction of the photo-induced phase. k0, Ea, and Ea* were evaluated as 1.28 × 107 ± 2.6 s−1, 4002 ± 188 cm−1, and 546 ± 318 cm−1, respectively. The value of Ea is much larger than that of the relaxation process for the typical light-induced spin crossover effect (Ea ≈ 1000 cm−1). Room-temperature photo-switching is an important issue in the field of optical functional materials. The present system is useful for the demonstration of high-temperature photo-switching material