Vibrations and chemical states of iron ions in soda‐lime glasses determined by element‐specific X‐ray analyses

We systematically study medium‐range structures including more than three neighboring atoms around iron ions (Fe²⁺ and Fe³⁺) in soda‐lime glass samples with low iron oxide concentrations (M_Fe2O3) and a wide number ratio of Fe²⁺ to all iron ions (Fe²⁺/Σ_nFe). The precise medium‐range structures around iron ions in glass have not yet been revealed because of a lack of the appropriate measurement methods. To avoid this problem, we used element‐specific nuclear resonant inelastic scattering (NRIS) with synchrotron X‐rays to observe the vibrations of iron ions (⁵⁷Fe). The vibrations are related to medium‐range structures with more than three neighboring atoms and to the potential asymmetry and the coordination environment, around iron ions. The NRIS method has high sensitivity and can measure over a wide concentration range. Linear combination fitting of the X‐ray absorption fine structure spectra, which measures only the first neighbors but is a faster than using the NRIS method, was also used additionally. A systematically produced set of glasses with 0.015–5 wt% M_Fe2O3 and 0–0.85 Fe²⁺/Σ_nFe was measured with these methods. It was found that the soda‐lime glass possessed two different medium‐range structures with different iron ion valences (~2+ or ~3+), which were determined by the Fe²⁺/Σ_nFe, and that these structures were generated during production of the glass. Moreover, these medium‐range structures were the same from 0.015 to 5 wt% M_Fe2O3.     

Acoustic roles of the laryngeal cavity in vocal tract resonance

The acoustic effects of the laryngeal cavity on the vocal tract resonance were investigated by using vocal tract area functions for the five Japanese vowels obtained from an adult male speaker. Transfer functions were examined with the laryngeal cavity eliminated from the whole vocal tract, volume velocity distribution patterns were calculated, and susceptance matching analysis was performed between the laryngeal cavity and the vocal tract excluding the laryngeal cavity (vocal tract proper). It was revealed that the laryngeal cavity generates one of the formants of the vocal tract, which is the fourth in the present study. At this formant, the resonance of the laryngeal cavity (the 1/4 wavelength resonance) induces the open-tube resonance of the vocal tract proper (the 3/2 wavelength resonance). At the other formants, on the other hand, the vocal tract proper acts as a closed tube, because the laryngeal cavity has only a small contribution to generating these formants and the effective closed end of the whole vocal tract is the junction between the laryngeal cavity and the vocal tract proper.     

Multiple photofragmentation pathways with different recoil anisotropy from a metal-ion-ligand complex

Spatial recoil anisotropy that is dependent upon the fragment-ion species is reported for the first time for a metal-ion-ligand complex after a single photoexcitation process by linearly polarized light. Upon excitation to the lowest three excited states of Mg+-ICH3, originating from the Mg+2P states, fragment ions of MgI+ and ICH+3 are found to have clear and different angular dependences, which are also characteristic of the excited states. These are explained from the results of theoretical work in that the calculated ground-state complex has a bent structure and further in that each transition dipole moment vector of the complex almost coincides with the Mg+ 3p orbital lobe direction in each case. The fragment ions are concluded to be formed along dissociative potential surfaces which are crossed by the initially excited states, in a much faster process than the rotational period of the complex.     

First stereoselective synthesis of 2-deoxy-alpha-D-ribosyl-1-phosphate: novel application of crystallization-induced asymmetric transformation

A first stereoselective synthesis of bis(cyclohexylamine) 2-deoxy-alpha-D-ribosyl-1-phosphate has been achieved. The synthesis features a key crystallization-induced asymmetric transformation (AT) to generate a desired alpha-anomer in 99% yield at a 98.8:1.2 ratio of alpha/beta.     

Activation of electron transfer reduction of p-benzoquinone derivatives by intermolecular regioselective hydrogen bond formation

Electron transfer reduction of p-benzoquinones by cobalt tetraphenylporphyrin is enhanced significantly by the presence of o-bis(phenylcarbamoylmethyl)benzene (o-L) due to the regioselective hydrogen bond formation between the corresponding semiquinone radical anions and o-L, whereas m- and p-isomers (m-L and p-L) have no effect on the electron transfer equilibrium or the rate.     

Quadratic initial ideals of root systems

Let be one of the root systems , , and and write for the set of positive roots of together with the origin of . Let denote the Laurent polynomial ring over a field and write for the affine semigroup ring which is generated by those monomials with , where if . Let denote the polynomial ring over and write for the toric ideal of . Thus is the kernel of the surjective homomorphism defined by setting for all . In their combinatorial study of hypergeometric functions associated with root systems, Gelfand, Graev and Postnikov discovered a quadratic initial ideal of the toric ideal of . The purpose of the present paper is to show the existence of a reverse lexicographic (squarefree) quadratic initial ideal of the toric ideal of each of , and . It then follows that the convex polytope of the convex hull of each of , and possesses a regular unimodular triangulation arising from a flag complex, and that each of the affine semigroup rings , and is Koszul.     

l-Glutamate enzyme electrode involving amplification by substrate recycling

An enzyme electrode with an amplified response for l-glutamate is constructed by co-immobilizing l-glutamate oxidase and glutamate-pyruvate transaminase on a platinum disk electrode. With l-alanine (1 mM) in the solution, the sensitivity of the electrode to l-glutamate is greatly increased by the substrate recycling reaction between the two enzymes; the detection limit is 0.2 nM in the presence of l-alanine compared with 0.2 μM in its absence. The amplification factor for 1 μM l-glutamate is ca. 53.     

The similarity problem for 3−3 integer matrices

Using results from the similarity problem of 2?2 integer matrices, we derive an algorithm for the solution of the similarity problem for 3?3 integer matrices.     

An investigation of laser microprobe mass spectrometry (LAMMS) for polymer surface treatment and its inhomogeneity

Laser microprobe mass spectrometry was applied for the detection of inhomogeneity of the polycarbonate surface treated with silane coupling agent. Clear difference in spectrum patterns between the treatments with and without a non-ionic fluorocarbon surfactant was observed. The chemical bonds between silicon/zirconium and carbon have been confirmed to generate only in the presence of the surfactant which participates in homogenization of the surface.