Double-antibody homogeneous fluorescence immunoassay of phenytoin

A homogeneous fluorescence immunoassay suitable for quantifying 5–25 mg l^?1 phenytoin (5,5-diphenyl-2,4-imidazolidenedione) in serum is described. The fluorophor-labeled phenytoin and unlabeled phenytoin (analyte) compete for a limited number of anti-phenytoin antibody binding sites in the presence of anti-fluorophor antibodies. The label employed is a sulfonamido derivative of 2-naphthol-8-sulfonic acid (2-8) which, at neutral pH, undergoes excited-state proton transfer. Binding of anti 2-8 antibodies to the drug-fluorophor conjugate results in quenching of the conjugate base emission at 480 nm. The relative standard deviations are about 5%.     

The effects of incommensurability on the phonon modes in the one-dimensional superionic conductor K-hollandite

Polarized Raman and infrared spectra of the one dimensional (1-D) superionic conductor (K_2xMg_xTi(_8?x)O₁₆; x = 0.77) have been measured over the phonon frequency region 10–1000 cm^?1 as a function of temperature and pressure. The majority of the IR and Raman active modes predicted by group theory for the (Ti, Mg)O₆ framework were observed. The frequencies and their IR and Raman scattering cross-sections for the incommensurate lattice of K⁺ ions were calculated using a one dimensional linear chain model. This model assumes Coulomb interaction between nearest neighbors that are located in a sinusoidal potential due to the framework lattice. Several broad Raman bands were attributed to amplitudon type modes from the one dimensional incommensurate K⁺ ion sublattice. The IR active phason modes could not be identified unambiguously due to the underlying TiO framework vibrations which are known to possess large anharmonicity and oscillator strenghts.     

A photonic approach for microwave/millimeter-wave frequency measurement using stimulated brillouin scattering in single mode fiber

A photonic approach for microwave/millimeter-wave (MMW) frequency measurement is proposed and demonstrated based on stimulated Brillouin scattering (SBS) of a 20-km standard single mode fiber (SSMF). After the MMW signal is modulated to a laser source with two sidebands using optical carrier suppression (OCS) modulation, its frequency can be easily measured by monitoring the SBS-induced amplification with a power meter. Due to the 1-pm resolution of a tunable pump laser source, a frequency measurement range of 1–40 GHz is demonstrated in our experiment with a frequency resolution of 125 MHz. We believe the frequency measurement range can be further extended to satisfy photonic radar front-end processing application.     

Isoscattering deformations for complete manifolds of negative curvature

We construct continuous families of nonisometric metrics on simply connected manifolds of dimension n ≥ 9which have the same scattering phase, the same resolvent resonances, and strictly negative sectional curvatures. This situation contrasts sharply with the case of compact manifolds of negative curvature, where Guillemin/Kazhdan, Min-Oo, and Croke/Sharafutdinov showed that there are no nontrivial isospectral deformations of such metrics.     

A new stepwise synthesis of a family of propylamines derived from diatom silaffins and their activity in silicification

A new method for the stepwise synthesis of propylamines containing fragments of N-methyl propylamine as found in diatom bioextracts is presented and their activity in silicic acid condensation is described.     

On the number of rainbow spanning trees in edge-colored complete graphs

A spanning tree of a properly edge-colored complete graph, $K_n$, is rainbow provided that each of its edges receives a distinct color. In 1996, Brualdi and Hollingsworth conjectured that if $K_{2m}$ is properly $(2m?1)$-edge-colored, then the edges of $K_{2m}$ can be partitioned into $m$ rainbow spanning trees except when $m=2$. By means of an explicit, constructive approach, in this paper we construct $?\sqrt{6m+9}∕3?$ mutually edge-disjoint rainbow spanning trees for any positive value of $m$. Not only are the rainbow trees produced, but also some structure of each rainbow spanning tree is determined in the process. This improves upon best constructive result to date in the literature which produces exactly three rainbow trees.     

Fermi surface and quasiparticle excitations of Sr2RhO4

The electronic structure of the layered 4d transition metal oxide Sr2RhO4 is investigated by angle resolved photoemission. We find well-defined quasiparticle excitations with a highly anisotropic dispersion, suggesting a quasi-two-dimensional Fermi-liquid-like ground state. Markedly different from the isostructural Sr2RuO4, only two bands with dominant Rh 4dxz,zy character contribute to the Fermi surface. A quantitative analysis of the photoemission quasiparticle band structure is in excellent agreement with bulk data. In contrast, it is found that state-of-the-art density functional calculations in the local density approximation differ significantly from the experimental findings.     

Approximate solution of the Percus-Yevick equation for a binary mixture of hard spheres with non-additive diameters

We present an approximate solution of the Percus-Yevick integral equation for a binary mixture of hard spheres with non-additive diameters. Defining R_ij the distance of closest approach between particles of species i and j by R ₁₂ = ½(R ₁₁ + R ₂₂) + α, we obtain a closed set of equations for the direct correlation functions c_ij (r) when 0 < α ? min [½(R ₂₂ - R ₁₁), ½R ₁₁]. Our expressions for c_ii (r), and for c ₁₂(r) in the range 0 < r ? ½[R ₂₂ - R ₁₁] - α, agree with those previously obtained by Lebowitz and Zomick.