A mononuclear iron(ii) complex, [Fe(L1)](PF) (1), and a related dinuclear one, [Fe(L2)](PF)·5HO·MeCN (2), were prepared, where L1 is a tridentate N coordinating Schiff-base ligand, 1-methyl-1,2,3-triazol-4-yl-methylideneamino-2-ethylpyridine, and L2 is a dimeric form ligand of L1, 1,1'-(1,2-ethanediyl)bis-1,2,3-triazol-4-yl-methylideneamino-2-ethylpyridine, and their magnetostructural relationships were investigated. Mononuclear 1 shows a gradual one-step spin crossover (SCO) from the low-spin (LS) state (S = 0) at room temperature (RT) to the mostly high-spin (HS) state (S = 2) at 470 K spanning a temperature range of more than 170 K, while dinuclear 2 shows an anomalous two-step SCO with a gradual transition in a first step from the LS-LS state at RT to around 432 K and then an abrupt spin transition centred at 432 K with 11 K wide hysteresis in a second step (T = 437 K and T = 426 K) reaching the mostly HS-HS state. Single crystal X-ray structure analyses revealed that the iron(ii) centre of mononuclear 1 has an N6 octahedral coordination environment with two tridentate L1 ligands, while the complex-cation of 2 has a dinuclear double helicate architecture as though a dimeric form of two complex-cations of 1 replaced their methyl group with a bridging ethylene chain. Both complexes have a cationic two-dimensional (2D) structure in which the 2D layer of mononuclear 1 is constructed of intermolecular CHN hydrogen bonds between adjacent complex-cations, while that of dinuclear 2 is constructed of both intermolecular π-π and CH/π interactions between neighboring helicates.

In contrast to mammals, higher plants have evolved to express diverse protein phosphatase 2Cs (PP2Cs). Of all Arabidopsis thaliana PP2Cs, members of PP2C subfamily A, including ABI1, have been shown to be key negative regulators of abscisic acid (ABA) signalling pathways, which regulate plant growth and development as well as tolerance to adverse environmental conditions. However, little is known about the enzymatic and signalling roles of other PP2C subfamilies. Here, we report a novel Arabidopsis subfamily E PP2C gene, At3g05640, designated AtPP2CF1. AtPP2CF1 was dramatically expressed in response to exogenous ABA and was expressed in vascular tissues and guard cells, similar to most subfamily A PP2C genes. In vitro enzymatic activity assays showed that AtPP2CF1 possessed functional PP2C activity. However, yeast two-hybrid analysis revealed that AtPP2CF1 did not interact with PYR/PYL/RCAR receptors or three SnRK2 kinases, which are ABI1-interacting proteins. This was supported by homology-based structural modelling demonstrating that the putative active- and substrate-binding site of AtPP2CF1 differed from that of ABI1. Furthermore, while overexpression of ABI1 in plants induced an ABA-insensitive phenotype, Arabidopsis plants overexpressing AtPP2CF1 (AtPP2CF1oe) were weakly hypersensitive to ABA during seed germination and drought stress. Unexpectedly, AtPP2CF1oe plants also exhibited increased biomass yield, mainly due to accelerated growth of inflorescence stems through the activation of cell proliferation and expansion. Our results provide new insights into the physiological significance of AtPP2CF1 as a candidate gene for plant growth production and for potential application in the sustainable supply of plant biomass.

The MnO-SiO2-type inclusions changed into MnO-Cr2O3 type inclusions in an Fe-Cr alloy deoxidised by Mn and Si with a low Si concentration by heat treatment at 1 473 K. At high Si content, the MnO-SiO2-type inclusion remained stable even after heat treatment. The change in the chemical composition of the oxide inclusions by heat treatment depended on the concentrations of Si and Cr in the Fe-Cr alloys. The mechanism of the change in the chemical composition of the oxide inclusions was investigated by using two experimental methods. The solubility of Cr2O3 in MnO-SiO2 was measured from 1 473 to 1 673 K. The solubility of Cr2O3 decreased with temperature. The other experiment was performed using a diffusion couple method between the Fe-Cr alloy and MnO-SiO2 at 1 473 K to investigate a reaction between them. The formation of MnO-Cr2O3 was observed at the interface. It is found that both the decrease in solubility of Cr2O3 and diffusion of Mn, Cr, and Si at the interface between the Fe-Cr alloy and oxide inclusions are important for controlling the change in the chemical composition of the oxide inclusions in the Fe-Cr alloy by heat treatment at 1 473 K.

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It is known that the oxide composition in stainless steel changes during heat treatment; however, the precise conditions to cause change are not clear. Therefore, the conditions necessary to change the oxide composition by heat treatment have been investigated using steels with different concentrations of Si, Mn, Ni and Cr. The MnO-SiO 2 type inclusions changed into MnO-Cr 2 O 3 type inclusions in steel containing 18%Cr and 8%Ni after heat treatment with a low silicon concentration. At high silicon content, the MnO-SiO 2 type inclusion was stable after heat treatment. The change in the composition of oxide inclusions owing to heat treatment depended on the concentrations of Cr in steel. The critical Si content, below which the oxide composition change was observed after the heat treatment, decreased with the decrease in Cr content. In steel containing 1%Cr, the oxide composition change was not observed.