237Np and 57Fe Mössbauer study of NpFeGa5

⁵⁷Fe and ²³⁷Np Mössbauer ōmeasurements have been performed for NpFeGa₅, which is one of the so-called neptunium 1-1-5 compounds. The ⁵⁷Fe Mössbauer spectra below T _N = 118 K show the magnetically ordered state. The magnitude of the hyperfine magnetic field at the ⁵⁷Fe nucleus is determined to be 1.98 ± 0.05 T at 10 K. From the ²³⁷Np Mössbauer spectrum at 10 K, the hyperfine magnetic field at the ²³⁷Np nucleus is 203 T and the hyperfine coupling constant is determined to be 237 T/μ_B using the Np atomic magnetic moment of 0.86 μ_B determined by the neutron diffraction study.     

On ergodic theory of A. Schmidt's complex continued fractions over Gaussian field

We construct a natural extension transformation associated with A. Schmidt's complex continued fractions. The transformation is defined on a subset of geodesics over a three dimensional hyperbolic space and an invariant measure for it is naturally induced from the hyperbolic measure. We discuss some applications of it to the metrical theory of continued fractions.     

The four-jet structure of large transverse momentum events inpp interactions at the ISR

Deep inelastic proton-proton collisions have been recorded with the Split-Field-Magnet Detector (SFM) at the CERN Intersecting Storage Rings (ISR) by triggering on a single particle at high transverse momentum. Full reconstruction of the charged particles in these collisions was performed. In this paper we demonstrate the existence of a structure comprised of four jet-like clusters, two longitudinal and two transverse with respect to the beam, as would be expected from hard scattering of proton constituents.     

F 2-FDG NMR imaging of the brain in rat

Images of the rat head reflecting glucose utilization were obtained using 2-fluoro-2-deoxy-D-glucose (2-FDG) and ¹⁹F nuclear magnetic resonance (NMR) imaging. Spatial heterogeneity of glucose utilization in the rat head was clearly demonstrated showing significantly higher glucose utilization in the brain as compared to the surrounding tissues. Although the potential adverse effects of the high doses of 2-FDG (400 mg/kg) needed to perform the study preclude immediate application of this technique to clinical quantitative glucose utilization studies, the present study shows potential for future development of glucose utilization imaging by NMR.     

Spontaneous polymerization mechanism of electron‐accepting substituted quinodimethane with vinyl ether and cyclic ketene acetal

The spontaneous reactions of 1‐(2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione‐5‐ylidene)‐4‐(dicyanomethylene)‐2,5‐cyclohexadiene (QM‐1) with a vinyl ether, butyl vinyl ether (BVE), and a cyclic ketene acetal, 2‐methylene‐1,3‐dioxepane (MDOP), were investigated. The reaction of QM‐1 with BVE produced a terpolymer composed of QM‐1, 7‐butoxy‐8,8‐dicyanoquinodimethane, and BVE units as a hexane‐insoluble product and a one‐to‐one adduct of methylene Meldrum's acid and BVE as a hexane‐soluble product. The spontaneous reaction of QM‐1 with BVE produced, in the presence of 2,2,6,6‐tetramethylpiperidine‐1‐oxy (TEMPO), a terpolymer carrying TEMPO units in the chain ends, and in the presence of methanol, a one‐to‐one‐to‐one adduct of QM‐1, BVE, and methanol was isolated. The spontaneous reaction with bulkier, electron‐donating MDOP produced a low‐molecular‐weight alternating cooligomer of QM‐1 with MDOP. The spontaneous polymerization was proposed to proceed via a zwitterionic intermediate taking two forms, gauche and trans, depending on the bulkiness of the comonomer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3800–3811, 2004     

Geometries and excited-state dynamics of van der Waals dimers and higher clusters of 1-cyanonaphthalene

Mass-selected resonant two-photon ionization and infrared-ultraviolet double-resonance spectroscopies are combined with correlated (second Moller-Plesset perturbation) quantum chemistry calculation to probe electronic spectra and ground-state geometries of the jet-cooled dimer and higher clusters of 1-cyanonaphthalene. The results indicate that the dimer and trimer have stacked geometries, consistent with the highly efficient, rapid excimer formation that follows photoexcitation of the ground-state clusters.     

Studies on catalytic asymmetric Nozaki-Hiyama propargylation

Catalytic asymmetric Nozaki-Hiyama propargylation with ligand 1c proceeds with good to excellent enantioselectivity. Tuning of ligand 1 dramatically changes the enantioselectivity, and we propose models A and B to explain the change and outcome of the enantioselectivity.     

Experimental and theoretical studies of the conformational structures of the mixed clusters of 1-cyanonaphthalene with water

A concerted experimental (mass-selective, double-resonance laser spectroscopic technique) and theoretical (correlated quantum chemistry calculation) study of hydrogen-bonded clusters of 1-cyanonaphthalene (CNN) with water has been carried out to probe geometrical structures of the conformational isomers. The structures of the two low-energy conformers of CNN-H2O and CNN-(H2O)2, calculated at the MP2/cc-pVDZ level of theory, are consistent with the mass-selective infrared-ultraviolet double-resonance spectra and the partially resolved rotational band contours of the S1 <-- S0 origin bands. The facile loss of a neutral water molecule from the cluster ion of CNN-(H2O)2, relative to that of CNN-H2O, is in accord with the proposed structures of the clusters.