Influence of hydrogen absorption on magnetic properties of Zr(Fe1−xVx)2 ternaries

Measurements of magnetization, susceptibility and Mössbauer effect were made on Zr(Fe_1?xV_x)₂ ternaries and their hydrides. Absorbed hydrogen leads to a large increase (20–30%) in volume without a change in the crystal structure. Ferromagnetism in the Fe-rich region is enhanced by hydrogen absorption, whereas hydrogenation leads to suppression of superconductivity in the V-rich range. The Fe moments in the Zr(Fe_1?xV_x)₂ hydrides are remarkably larger than those in the corresponding host compounds. The Fe moment in the β-ZrFe₂ hydride extrapolated reaches to 2.9μ_B, which exceeds the saturation value in bcc Fe. The hyperfine fields of ⁵⁷Fe in both Zr(Fe_0.8V_0.2)₂ and the hydride distribute widely, indicating that the Fe moments are very sensitive to the local environment arround the Fe atoms. Arguments are presented that it is possible to interprete the Fe moment increase by hydrogenation in terms of a decrease in occupancy of the 3d-band state due to electron transfers from Fe to hydrogen and/or vanadium.     

Biosynthesis of phytoecdysteroids in Ajuga hairy roots: clerosterol as a precursor of cyasterone, isocyasterone and 29-norcyasterone

Feeding studies of six ¹³C-labeled sterols, including clerosterol, to hairy roots of Ajugareptans var. atropurpurea have established that clerosterol is a precursor of three phytoecdysteroids, cyasterone, isocyasterone and 29-norcyasterone.     

Crystallization and Reduction of Sol-Gel-Derived Zinc Oxide Films by Irradiation with Ultraviolet Lamp

Structural changes in sol-gel films with photo-irradiation were investigated using zinc oxide (ZnO) derived from zinc acetate. The exposure of the films to an ultraviolet lamp induced hexagonal ZnO crystals in a relatively dense amorphous structure. On the other hand, the formation of zinc metal was found in a porous gel film. The photo-induced crystallization and reduction are ascribed to the electronic excitation in the metastable non-crystalline states.     

Pd(O)-catalyzed electroreductive cleavage of allylic acetates

Pd(O)-catalyzed electroreductive cleavage of allylic acetates yielding alkenes and/or allyltrimethylsilanes is described. Deprotection of allyl esters can be performed in the same electrolysis system.     

Synthesis and properties of the [2.2]paracyclophane‐containing conjugated polymer with benzothiadiazole as an electron acceptor

A novel donor–acceptor type conjugated polymer based on PPE with [2.2]paracyclophane and benzothiadiazole units in the main chain was synthesized by the Sonogashira coupling reaction. The obtained polymer was quite soluble in common organic solvents, and the transparent and uniform thin film of the polymer was obtained easily by casting or spin‐coating from a toluene solution. The polymer showed an extension of π‐delocalization via the through‐space with π‐π stacking according to the UV–visible (UV–vis) absorption spectra in comparison with that of the model compound. The polymer exhibited orange photoluminescence in solution (fluorescence quantum efficiency = 0.13) and in the solid state. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5891–5899, 2004     

Syntheses of cerulenin and its analogs. II. Synthesis and biological activity of dl-carbacerulenin, a carbocyclic analog of cerulenin.

2,3-Epoxy-4-hydroxy-4-((E,E)-3,6-octadienyl)cyclopentanone (dl-carbacerulenin 5) was synthesized via the epoxyketones 15a and 15b as a mimic of the active form of the antibiotics cerulenin 1, a potent inhibitor of fatty acid synthetase (FAS). The monobenzyl ethers (12 and 13), synthetic intermediates of 15, were prepared by direct benzylation of the epoxycyclopentene (7). Inhibitory activity of synthesized 5 toward yeast FAS was less than that of cerulenin by a factor of 1000.     

Synthesis of diversely functionalized hexahydropyrrolo[2,3-b]indoles using domino reactions, olefination, isomerization and Claisen rearrangement followed by reductive cyclization

Hexahydropyrrolo[2,3-b]indoles 6 were synthesized in five steps from indolin-3-one 8 by a general and efficient method, in which elements of molecular diversity were readily added onto the 3a-position of the pyrrolo[2,3-b]indole ring system. Horner-Wadsworth-Emmons reaction of 2-allyloxyindolin-3-ones 7, derived from indolin-3-one 8 and a variety of allylic alcohols, smoothly proceeded with successive Claisen rearrangement to give the corresponding 3-allyl-3-cyanomethylindolin-2-ones 15. Indolin-2-ones 15 were converted into pyrrolo[2,3-b]indoles 6 using partial hydrolysis followed by reductive cyclization with LiAlH(4). Synthesis of N-methylated pyrrolo[2,3-b]indole derivatives 23 and 26 is also described.     

Influence of SO2 on the durability of Ag/Al2O3 catalyst in lean NOx reduction by ethyl alcohol

The influence of SO₂ (200 ppm) on the durability of a Ag/Al₂O₃ catalyst for the reduction of NOx with ethyl alcohol was examined. The results strongly suggest that H₂O in diesel engine exhaust is essential for the high durability of Ag/Al₂O₃ catalyst in the presence of SO₂.     

Photoreactivity of amino acids: tryptophan-induced photochemical events via reactive oxygen species generation.

Tryptophan (Trp), an aromatic amino acid, is a constituent of peptides/proteins and is also a precursor of serotonin, kynurenine derivatives, and nicotinamide adenine dinucleotides. There have been a number of reports on photochemical reactions involving peptides/proteins which contain Trp that showed significant photodegradation, dimerization, and photoionization. The photochemical properties of Trp have not been fully elucidated, and this would provide novel insight into the handling of Trp-containing peptides/proteins. Consequently, we have been trying to evaluate the photochemical properties of Trp, as well as other essential amino acids, focusing on their photosensitivity, photodegradation, and their ability to induce lipid peroxidation. Among all the essential amino acids tested, Trp exhibited the maximal level of superoxide anion generation under 18 h of light exposure (30000 lux). UV spectral analysis of Trp suggested the absorbability of UVA/B light, and exposure of Trp, in both solid and solution states, to UVA/B light resulted in significant photodegradation (t(0.5): 18 h) and gradual color changes. In addition, photoirradiated Trp generated lipoperoxidant, a causative agent of photoirritation, and this might be associated with ROS generation.     

Synthesis of optically active oligomers consisting of chiral phosphorus atoms: capture of an intermediate between a polymer and a small molecule

We describe here the synthesis and properties of novel optically active oligophosphines. The effect of the number of chiral phosphorus atoms on thermal properties and conformations is documented. In this study, we captured an intermediate between a polymer and a small molecule. To the best of our knowledge, it is primarily observed that a small molecule transforms into a polymer via an amorphous small molecule during the process of the elongation of the oligomer main chain.