Time-resolved fluorometric analysis of carbohydrates labeled with amino-aromatic compounds by reductive amination

We examined the formation of complexes between terbium ion (Tb3+) and carbohydrates labeled with aminobenzene compounds. Of the examined compounds, carbohydrates labeled with 4-aminosalicylic acid showed intense fluorescence with Tb3+ in the presence of cetylpyridinium chloride at pH 6.0. Calibration curves for maltose derivative showed good linearity between 5 pmol and at least 600 pmol, with good reproducibility. We applied the proposed technique to binding studies between manno-oligosaccharides and Concanavalin A.     

Direct evidence for an intrinsic square vortex lattice in the overdoped high- T(c) superconductor La(1.83)Sr(0.17)CuO(4+delta)

We report here the first direct observations of a well ordered vortex lattice in the bulk of a La(2-x)Sr(x)CuO(4+delta) single crystal (slightly overdoped, x = 0.17). Our small angle neutron scattering investigation of the mixed phase reveals a crossover from triangular to square coordination with increasing magnetic field. The existence of an intrinsic square vortex lattice has never been observed in high-temperature superconductors and is indicative of the coupling of the vortex lattice to a source of anisotropy, such as those provided by a d-wave order parameter or the presence of stripes.     

The synthesis of bicyclo[6.2.0]decapentaene

The parent bicyclo[6.2.0]decapentaene is synthesized for the first time by thermal ring opening of its valence isomer. Thermal dimerization of the compound is also described.     

Preparation of soluble and fusible poly(2,5-dimethoxy-1,4-phenylene)

Poly(2,5-dimethoxy-1,4-phenylene) was prepared by oxidative polymerization of p-dimethoxybenzene with aluminum chloride and copper(II) chloride in nitrobenzene under reduced pressure. The polymers obtained were soluble in sulfuric acid and fusible at 320°C. The intrinsic viscosity of the polymer was ca. 0.07 in sulfuric acid. Demethylation of methoxy groups did not occur during the polymerization.     

Lasing conditions in recombining helium plasmas

Lasing conditions for He have been evaluated numerically. We have used a collisional radiative model to calculate overpopulation densities Δn_ij, which are defined as differences between population densities per unit statistical weight of the upper and lower excited levels i and j, respectively. Laser oscillations for the level pairs 2¹P-3¹S, 2¹P-4¹S, 2¹P-3¹D, 2¹P-4¹D, 3¹D-4¹F, 3¹P-4¹S, 3¹P-4¹D, and 3³P-4³S are possible when the electron densities are within well defined limits at low electron temperature (T_e = 0.1 eV). For level pairs of the singlet state, the inversion mechanism for He is the same as for H. Only collisional processes produce population inversion in the triplet level pair 3³P-4³S.