Image analysis of the spatial distribution of paramagnetic Pr3+ ions in a polymer gel by a 1H-chemical shift NMR imaging method

¹H-chemical shift NMR imaging patterns of a poly(methacrylic acid) gel containing water with paramagnetic praseodymium ions(Pr³⁺) were successfully observed, in order to elucidate spatial distribution of Pr³⁺ ions in the gel. The ¹H chemical shift of water associated with Pr³⁺ ions in the gel moves largely downfield. By analyzing these experimental results, the immersion process of Pr³⁺ ions into the network of the polymer gel was spatially clarified. Further, it is shown that the chemical shift NMR imaging method is a useful means for determining the spatial distribution of paramagnetic metal ions in polymer gels.     

Living polymerizations of acrylic monomers with aluminioporphyrin

Aluminioporphyrin was found to be an excellent initiator for the living polymerizations of methacrylates, acrylates, and methacrylonitrile. Porphinatoaluminium thiolate and enolate were effective in the dark, different from methylporphinatoaluminium which requires irradiation by visible light. The addition of pyridine was necessary for the polymerization of methacrylonitrile, which was accelerated by visible light. By using the living polymer of methyl methacrylate as initiator, block copolymers from acrylic monomers could be synthesized. A system composed of aluminioporphyrin and trialkylaluminium was found highly active for the polymerization of methacrylates.     

Optical second-harmonic generation study of incorporation of nitrogen atoms at Si(1 0 0) surfaces

The kinetics of N incorporation into Si layers has been studied on the Si(1 0 0) surface probing surface dangling bonds with an optical second-harmonic (SH) generation during surface exposure to N atoms generated by a radio frequency N₂ plasma. It is observed that SH intensity decreases with N dose. The rate of decrease in SH intensity apparently decreases with surface temperature, whereas total amount of N atoms taken on the surface remains constant. This fact suggests that N atoms are incorporated at the subsurface layers at higher temperatures. It is shown that the N incorporation at the subsurface layers proceeds by the indiffusion of N atoms either directly or indirectly via intermediate, metastable adsorption at the first surface layer. Applying Kisliuk adsorption model, activation energies of the N indiffusion are evaluated to be 0.30 ± 0.03 and 0.34 ± 0.05 eV for the indirect and direct path, respectively.     

Incommensurate spin fluctuations in hole-overdoped superconductor KFe2As2

A neutron scattering study of heavily hole-overdoped superconducting KFe2As2 revealed a well-defined low-energy incommensurate spin fluctuation at [π(1 ± 2 δ),0] with δ = 0.16. The incommensurate structure differs from the previously observed commensurate peaks in electron-doped AFe2As2 (A = Ba, Ca, or Sr) at low energies. The direction of the peak splitting is perpendicular to that observed in Fe(Te,Se) or in Ba(Fe,Co)2As2 at high energies. A band structure calculation suggests interband scattering between bands around the Γ and X points as an origin of this incommensurate peak. The perpendicular direction of the peak splitting can be understood within the framework of multiorbital band structure. The results suggest that spin fluctuation is more robust in hole-doped than in electron-doped samples, which can be responsible for the appearance of superconductivity in the heavily hole-doped samples.     

Classification of torus manifolds with codimension one extended actions

The purpose of this paper is to classify torus manifolds (M ²ⁿ , T ⁿ ) with codimension one extended G-actions (M ²ⁿ , G) up to essential isomorphism, where G is a compact, connected Lie group whose maximal torus is T ⁿ . For technical reasons, we do not assume torus manifolds are orientable. We prove that there are seven types of such manifolds. As a corollary, if a nonsingular toric variety or a quasitoric manifold has a codimension one extended action then such manifold is a complex projective bundle over a product of complex projective spaces.     

An application of a boundary element method to natural convection

The direct boundary element method is applied to the numerical modelling of thermal fluid flow in a transient state. The Navier-Stokes equations are considered under the Boussinesq approximation and the viscous thermal flow equations are expressed in terms of stream function, vorticity, and temperature in two dimensions. Boundary integral equations are derived using logarithmic potential and time-dependent heat potential as fundamental solutions. Boundary unknowns are discretized by linear boundary elements and flow domains are divided into a series of triangular cells. Charged points are translated upstream in the numerical evaluation of convective terms. Unknown stream function, vorticity, and temperature are staggered in the computational scheme.

Simple iteration is found to converge to the quasi steady-state flow. Boundary solutions for two-dimensional examples at a Reynolds number 100 and Grashoff number 10⁷ are obtained.     

Fuzzy semiprime ideals in semigroups

In this paper we shall introduce the notion of fuzzy semiprimality in a semigroup, which is an extension of semiprimality in it, and characterize a semigroup that is a semilattice of simple semigroups in terms of fuzzy semiprimality.     

Introduction of the trihydrated hydronium ion concept into the dyeing mechanism of nylon with polybasic dyes

Summary The adsorption isotherms of polybasic acid dyes (two dibasic dyes and two tribasic dyes) on three kinds of nylon fibers at constant p_H (3.5) have been determined at 90 °C. The nylon fibers, Nylon-1, –2 and –3 had amino group analyses of 25, 54 and 95 meq/kg, respectively. From the adsorption isotherms the saturation value of the dyes on each nylon fiber was calculated. For the dibasic dyes, the saturation value on each nylon fiber was very near the amino group content of the fiber. This indicates that these dyes are adsorbed stoicheiometrically on each nylon fiber. For the tribasic dyes, the stoichiometric behavior was observed only on Nylon-3. A crude calculation was made of the distance between amino groups in each nylon fiber. It was seen from the scale model of the dyes that the distance of sulfonic acid groups in the dye molecule is much smaller than that of amino groups in the fiber. The H₉O₄ ⁺ bridge hypothesis was proposed in order to explain how a polybasic dye can physically saturate fixed sites.

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Zusammenfassung Die Adsorptionsisothermen von mehrbasischen Säurefarbstoffen (zwei dibasische Farbstoffe und zwei tribasische Farbstoffe) an Nylonfasern von dreierlei Art bei konstantem p_H (3.5) wurden bei 90 °C bestimmt. Die Nylonfasern Nylon-1, –2 und –3 ergeben bei Aminogruppenanalysen Werte von 25, 54 und 95 mäqu/kg. Aus Adsorptionsisothermen wurden die Sättigungswerte für diese Farbstoffe auf jeder Art Nylonfaser berechnet. Für die dibasischen Farbstoffe wurden die Sättigungswerte auf jeder Nylonfaser sehr nahe dem Aminogehalt in der Faser gefunden. Das zeigt, daß diese Farbstoffe auf den Nylonfasern stoichiometrisch adsorbiert werden. Bei den tribasischen Farbstoffen wurde das stöchiometrische Verhalten nur auf Nylon-3 gefunden. Die Abstände zwischen den Aminogruppen in jeder Nylonfaserart wurde näherungsweise berechnet. Aus dem Molekülmodell des Farbstoffes stellt sich heraus, daß der Abstand zwischen den Sulfonsäuregruppen im Farbstoffmolekül viel kürzer als der zwischen irgendwelchen Aminogruppen in der Faser ist. Deshalb wird eine H₉O₄ ⁺-Brücken-Hypothese vorgeschlagen, um zu klären, wie ein mehrbasischer Farbstoff feste Plätze physikalisch absättigen kann.

     

On SL(3, ℝ)-actions on 4-spheres

We construct a natural, continuous SL(3, ℝ)-action on S ⁴ which is an extension of the SO(3)-action ψ of Uchida. The construction is based on the Kuiper theorem asserting that the quotient space of ℂP(2) by complex conjugation is S ⁴. We also give a new proof of the Kuiper theorem. __________ Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 5, pp. 99–105, 2005.