High-spin states in 155Dy and 154Dy from (12C,xn, γ) studies

Levels in ¹⁵⁵Dy and ¹⁵⁴Dy were studied using ${}^{146}\text{Nd}\text{(}{}^{12}\text{C}\text{, x}\text{n}\text{, γ)}$ reactions. Excitation functions between 57 MeV and 109 MeV, γ-angular distributions and γ-γ-time three dimensional coincidence relationships were determined. The most intense feature of the ¹⁵⁵Dy spectrum is a cascade of stretched E2 transitions between levels of the strongly mixed positiveparity band arising from the $\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}\text{, N = 6}$ shell-model state. Several of the strong γ-rays associated with a 6 μs isomer are also observed and placed in this decay scheme with this $\text{11}\text{2}$^? isomeric state of ¹⁵⁵Dy at 233.4 keV. A less strongly populated rotational band is based on this $\text{11}\text{2}$^? [505] orbital. The available information on ¹⁵⁵Dy from this and previous studies is discussed to arrive at a consistent interpretation. Coriolis mixing calculations are performed for the positive parity band and compared with the experimental data. Additional transitions of the ground rotational band in ¹⁵⁴Dy are identified up to the level with spin 14⁺ (18⁺). For the spins higher than 14 “back-bending” occurs. Transitions from states of a β-vibrational band are confirmed.     

Liquid—liquid equilibrium data: Their retrieval,correlation and prediction Part II: Correlation

The correlation of liquid—liquid equilibrium data using models for the liquid phase activity coefficients — for example NRTL and UNIQUAC — is reviewed. Different numerical procedures used in the computation of liquid—liquid equilibrium compositions on the basis of these models are evaluated. Methods for obtaining parameters from liquid—liquid equilibrium data are described, and a method leading to improved representation of tie lines using relatively few parameters is recommended. The NRTL and UNIQUAC equations are compared with respect to their ability of representing binary and ternary liquid—liquid equilibrium data. The UNIQUAC equation appears to be more convenient to use and to correlate the data slightly better than does NRTL with the same number of parameters.     

Spectral Deformation for Two-Body Dispersive Systems with e.g. the Yukawa Potential

We find an explicit closed formula for the k’th iterated commutator \({\text{ad}_{A}^{k}}(H_{V}(\xi ))\) of arbitrary order k ? 1 between a Hamiltonian \(H_{V}(\xi )=M_{\omega _{\xi }}+S_{\check V}\) and a conjugate operator \(A=\frac{\mathfrak{i}}{2}(v_{\xi}\cdot\nabla+\nabla\cdot v_{\xi})\), where \(M_{\omega _{\xi }}\) is the operator of multiplication with the real analytic function ω _ξ which depends real analytically on the parameter ξ, and the operator \(S_{\check V}\) is the operator of convolution with the (sufficiently nice) function \(\check V\), and v _ξ is some vector field determined by ω _ξ . Under certain assumptions, which are satisfied for the Yukawa potential, we then prove estimates of the form \(\| {{\text{ad}_{A}^{k}}(H_{V}(\xi ))(H_{0}(\xi )+\mathfrak{i} )}\|\leqslant C_{\xi }^{k}k!\) where C _ξ is some constant which depends continuously on ξ. The Hamiltonian is the fixed total momentum fiber Hamiltonian of an abstract two-body dispersive system and the work is inspired by a recent result [3] which, under conditions including estimates of the mentioned type, opens up for spectral deformation and analytic perturbation theory of embedded eigenvalues of finite multiplicity.     

Liquid-phase microextraction and capillary electrophoresis of acidic drugs

Vial liquid-phase microextraction (LPME) combined with capillary electrophoresis (CE) was evaluated for the determination of the acidic drugs ibuprofen, naproxen, and ketoprofen present in water samples and in human urine. The 2.5 mL samples containing the drugs were filled into conventional vials and subsequently acidified by 250 microL of 1-10 M HCl. Porous hollow fibers of polypropylene containing 25 microL of an aqueous solution of 0.01-0.1 M NaOH (acceptor solution) and with dihexyl ether immobilized in the pores of the wall were placed into each of the samples. The acidic drugs were extracted from the acidified sample solutions into the dihexyl ether phase, in the pores of the hollow fiber, and further into the alkaline acceptor solution forced by high partition coefficients. The drugs were extracted almost quantitatively (75-100% extraction efficiency) from the 2.5 mL samples and into the 25 microL acceptor solutions, providing 75-100 times preconcentration. The acceptor solutions were collected for automated CE analysis, which enabled the drugs to be detected down to the 1 ng/mL level.     

Synthesis of an influenza neuraminidase inhibitor intermediate via a highly diastereoselective coupling reaction

[reaction: see text]. A highly diastereoselective coupling reaction between TBSOP (3) and trityl sulfenimine 4 was developed which provided influenza neuraminidase inhibitor intermediate 7 in 80% yield and >99% de after crystallization. The reaction was shown to be reversible with the high diastereoselectivity resulting from a favorable H-bonding interaction in the major diastereomer.     

A versatile spectrometer for secondary x-ray fluorescence excitation

Inexpensive research equipment for secondary x-ray fluorescence excitation is described. The primary beam from a high-powered x-ray tube is collimated onto the targets, six of which may be easily and safely interchanged. A collimator system ensures that the detector receives radiation from well defined areas of the sample. The geometry minimizes radiation from Compton scattering, the twice-scattered continuum radiation from the x-ray tube, and the characteristic lines from the secondary target. The unit is designed for use with standard x-ray tubes and generators, and is part of an energy-dispersive spectrometer used for multielement analysis. The performance of the system with a variety of samples is described.     

Computation of aromatic C3N4 networks and synthesis of the molecular precursor N(C3N3)3Cl6

The successful synthesis and structural characterization of molecules that represent segments of extended solids is a valuable strategy for learning metric and stereochemical characteristics of those solids. This approach has been useful in cases in which the solids are particularly difficult to crystallize and thus their atomic connectivity and overall structures become difficult to deduce with X-ray diffraction techniques. One such class of materials is the covalently linked C(x)N(y) extended solids, where molecular analogues remain largely absent. In particular, structures of C(3)N(4) solids are controversial. This report illustrates the utility of a simple molecule, N(C(3)N(3))(3)Cl(6), in answering the question of whether triazine based C(3)N(4) phases are layered or instead they adopt 3D structures. Here, we present density functional calculations that clearly demonstrate the lower stability of graphitic C(3)N(4) relative to 3D analogues.     

Plasmon profiles and deformations of sodium clusters in the 1g-shell

Absolute photoabsorption cross sections have been measured for free, singly ionized sodium clusters in the size range of 48 to 60 atoms. The measurements cover the wavelength interval from 390 to 590 nm (3.2-2.1 eV) in 14 steps. As in a previous series of measurements on smaller clusters, the spectra are dominated by a surface plasma oscillation of the valence electrons, that exhausts 70–80% of the dipole sum rule. The previously observed double structure of the resonance peak is not found, and therefore the interpretation of the profiles in terms of spheroidal deformations becomes more complicated. In this situation we compare the spectra with new calculations of the optical response of deformed clusters by Hirschmann. The calculations, which are made in a local representation of the Random Phase Approximation, agree well with the measured photoabsorption spectra.