Magnetic annealing effect in amorphous Fe100-xBx and Co100-xBx binary alloys

The uniaxial magnetic anisotropy induced by magnetic annealing was studied for rapidly quenched amorphous Fe_100-xB_x (12?x?25) and Co_100-xB_x (17?x?30) alloys. The value of induced uniaxial anisotropy constant K_ui increased with increasing B content from 1 x 10³ erg/cm³ at x = 12 to about 4 x 10³ erg/cm³ at x = 25 in Fe_100-xB_x alloy s exhibiting an inflection around x=20. While the value of K_ui in Co_100-xB_x alloys exhibits a maximum of about 6 x 10³ erg/cm³ aro round x=20. The compositional dependence of K_ui for both alloy systems can be explained roughly by the model of the directiona; occupation of B atom between ferromagnetic atoms.     

Simple method for preparation of nanostructure on microchannel surface and its usage for enzyme-immobilization

We developed a novel preparation method of nanostructure on the microchannel surface formed by sol-gel like simple treatment with 3-aminopropyltriethoxysilane, which is suitable for a highly efficient enzyme-immobilized microchannel reactor.     

Study on chemical reactions of isolated Mössbauer probes in solid gas matrices using in-beam Mössbauer spectroscopy

In-beam Mössbauer spectra of ⁵⁷Fe after ⁵⁷Mn (T _1/2= 1.45 min) implantation into a CH ₄ matrix and mixture matrices of CH ₄ and Ar at 18 K were measured. The spectrum obtained in the CH ₄ matrix was analyzed well with a doublet and a singlet peaks. These components were assigned to two constitutional isomers of Fe(CH ₄)\(_{\mathrm {2}}^{\mathrm {+}}\) as derived from density functional theory calculations and the Mössbauer parameters. In the case of the low concentration of CH ₄ with an Ar matrix, the Fe ⁺ (3d ⁷4s) in the excited state atomic configuration and Fe ⁺ (3d ⁶4s ¹) in the ground state were observed, as observed in our previous implantation experiment into Ar and Xe matrices. The formation yields of Fe(CH ₄)\(_{\mathrm {2}}^{\mathrm {+}}\) are discussed in term of the number of first-nearest-neighbor CH ₄ molecules around an Fe ⁺ ion.     

Structure and Reactivity of an Asymmetric Synthetic Mimic of Nitrogenase Cofactor

The Mo nitrogenase catalyzes the ambient reduction of N₂ to NH₃ at its M‐cluster site. A complex metallocofactor with a core composition of [MoFe₇S₉C], the M‐cluster, can be extracted from the protein scaffold and used to facilitate the catalytic reduction of CN^?, CO, and CO₂ into hydrocarbons in the isolated state. Herein, we report the synthesis, structure, and reactivity of an asymmetric M‐cluster analogue with a core composition of [MoFe₅S₉]. This analogue, referred to as the Mo‐cluster, is the first synthetic example of an M‐cluster mimic with Fe and Mo positioned at opposite ends of the cluster. Moreover, the ability of the Mo‐cluster to reduce C₁ substrates to hydrocarbons suggests the feasibility of developing nitrogenase‐based biomimetic approaches to recycle C₁ waste into fuel products.     

Intact Four‐atom Organic Tetracation Stabilized by Charge Localization in the Gas Phase

Several features distinguish intact multiply charged molecular cations (MMCs) from other species such as monocations and polycations: high potential energy, high electron affinity, a high density of electronic states with various spin multiplicities, and charge‐dependent reactions. However, repulsive Coulombic interactions make MMCs quite unstable, and hence small organic MMCs are currently not readily available. Herein, we report that the isolated four‐atom molecule diiodoacetylene survives after the removal of four electrons via tunneling. We show that the tetracation remains metastable towards dissociation because of the localization (91–95 %) of the positive charges on the terminal iodine atoms, ensuring minimum Coulomb repulsion between adjacent atoms as well as maximum charge‐induced attractive dipole interactions between iodine and carbon. Our approach making use of iodines as the positively charged sites enables small organic MMCs to remain intact.     

High-performance liquid chromatographic determination of clioquinol and its conjugates in biological materials

A method has been established for the determination of clioquinol (C) and its glucuronide (CG) and sulfate (CS) in biological materials. C and its internal standard were extracted with benzene-pyridine from samples. CG and CS were also hydrolyzed to C and extracted by the same method. The extracts were evaporated to dryness and redissolved in methanol. The methanol solution was subjected to HPLC using a column packed with Iatrobeads 6cp.2010 and a UV monitor (254 nm). The mobile phase was 0.1 M citric acid-methanol-n-hexane (8:86:6). The detection limit of C and 1 nmole and its recovery was above 92%.     

Synthesis, structure, and cooperative proton-electron transfer reaction of Bis(5,6-diethylpyrazinedithiolato)metal complexes (M = Ni, Pd, Pt)

New proton and electron donors, M(II)(HL)(2) (M = Ni, Pd, Pt; L = 5,6-diethylpyradzinedithiolate), as well as a proton and electron acceptor, Pt(IV)(L)(2), were prepared and characterized. The pH-dependent cyclic voltammetry of the M(II)(HL)(2) complexes revealed a favorable Gibbs free energy (K(com) > 1) for the proton and electron transfer reactions from M(II)(HL)(2) to M(IV)(L)(2); i.e., the equilibrium for the following reaction lies to the right: M(II)(HL)(2) + M(IV)(L)(2) <==>2M(III)(HL)(L).     

Neutron scattering study on dynamics of water molecules in MCM-41. 2. Determination of translational diffusion coefficient

Quasielastic neutron scattering (QENS) spectra of water-filled MCM-41 samples (pore diameters: 21.4 and 28.4 Angstrom) were measured over the temperature range 238-298 K and the momentum transfer range 0.31-0.99 A(-1) to investigate the dynamics of confined water molecules. The spectra, which consist mainly of contributions from the translational diffusion of water molecules, were analyzed by using the Lorentzian and the stretched exponential functions. Comparison of the fits indicated that the latter analysis is more reliable than the former one. The fraction of immobile water molecules located in the vicinity of the pore walls, which give an elastic component, was found to be 0.044-0.061 in both pores. The stretch exponent beta was determined as 0.66-0.80. It was shown that the translational diffusion of water molecules in the pores is decelerated by confinement and that the deceleration becomes marked with a decrease in pore size. The ratios of the translational diffusion coefficient D(T) of confined water to that of bulk water at room temperature were within a range of 0.47-0.63.     

A general method for the asymmetric synthesis of both enantiomers of 1-substituted 1,2,3,4-tetrahydro-β-carbolines employing pyroglutamic acid derivatives as chiral auxiliaries

9-(S)-Pyroglutaminyl-β-carbolines were allowed to react with a nucleophile (allyltributyltin or a silyl enol ether) in the presence of 2,2,2-trichloroethyl chloroformate to give 1,2-addition products in good yields and high diastereoselectivity. The chiral auxiliary at N-9 was readily removed by a mild hydrolysis. The same chiral source afforded both enantiomers by simply altering a protecting group of the amide nitrogen. That is, (S)-pyroglutaminyl groups which had an N-alkyl group afforded the (S) isomer, whereas the ones having an N-acyl group produced the (R) isomer of the addition products.     

On the blue-colored species,possibly assignable to a radical cation,formed by the aromatic hydrocarbon–sulfur dioxide–oxygen system: The polymerization of olefins initiated by aromatic hydrocarbons–oxygen in liquid sulfur dioxide

It was found that styrene in liquid sulfur dioxide polymerizes, giving polystyrene readily and quantitatively by addition of such aromatic hydrocarbons as anthracene and trans- or cis-stilbene in the presence of oxygen, and the polymerization proceeds via a cationic process. The observations on the electronic spectra and kinetics in the system suggested that the polymerization was initiated by an electron transfer from the aromatic hydrocarbon to oxygen, followed by the formation of styrene radical cation. Supporting evidence of the radical cation is that 1,1-diphenylethylene in liquid sulfur dioxide in the presence of oxygen shows a peak at λ_max = 605 mμ and reacts to give benzophenone and 1,1,3,3-tetraphenyl-butene-1, which are eliminated by addition of a radical or cation inhibitor.