Determination of α-decay branching ratios for 178, 179Hg

The neutron-deficient nuclides ^{182, 183}Pb were produced at the Accelerator Laboratory of the University of Jyv?skyl? by bombarding a ¹⁰⁷Ag target with ⁷⁸Kr ions. The nuclei of interest were separated using the RITU gas-filled separator and their radioactive decays investigated using the GREAT spectrometer. Correlating the $ \alpha$ decays of these Pb isotopes with those of their respective Hg daughters allowed $ \alpha$ -decay branching ratios of $\ensuremath b_\alpha($ ^178Hg) = 89(4)% and $\ensuremath b_\alpha($ ^179Hg) = 75(4)% to be deduced.     

First measurements of inclusive muon neutrino charged current differential cross sections on argon

The ArgoNeuT Collaboration presents the first measurements of inclusive muon neutrino charged current differential cross sections on argon. Obtained in the NuMI neutrino beam line at Fermilab, the flux-integrated results are reported in terms of outgoing muon angle and momentum. The data are consistent with the Monte Carlo expectation across the full range of kinematics sampled, 0°<θ(μ)<36° and 0相似文献   

Rhodium(I) and iridium(I) complexes of pyrazolyl-N-heterocyclic carbene ligands

Several Rh(I) and Ir(I) complexes containing an N-heterocyclic carbene-pyrazolyl chelate ligand have been synthesised. Determination of the single-crystal X-ray structure of the Ir(I) complex showed a novel binding mode with the iridium centre coordinated to two ligands via two carbene donors in preference to one ligand forming the entropically favoured chelate. The hydrogenation activity of several of these complexes was investigated along with that of previously synthesised Rh(I) and Ir(I) complexes containing an analogous phosphine-pyrazolyl chelate.     

Quasibound states in semiconductor quantum well structures

We present a study on quasibound states in multiple quantum well structures using a finite element model (FEM). The FEM is implemented for solving the effective mass Schrödinger equation in arbitrary layered semiconductor nanostructures with an arbitrary applied potential. The model also includes nonparabolicity effects by using an energy dependent effective mass, where the resulting nonlinear eigenvalue problem was solved using an iterative approach. We focus on quasibound/continuum states above the barrier potential and show that such states can be determined using cyclic boundary conditions. This new method enables the determination of both bound and quasibound states simultaneously, making it more efficient than other methods where different boundary conditions have to be used in extracting the relevant states. Furthermore, the new method lifted the problem of quasibound state divergence commonly seen with many other methods of calculation. Hence enabling accurate determination of dipole matrix elements involving both bound and quasibound states. Such calculations are vital in the design of intersubband optoelectronic devices and reveal the interesting properties of quasibound states above the potential barriers.     

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Assaying neurotransmitters in and around single neurons with information-rich detectors

Techniques to study the chemical environment in and around individual neurons are reviewed, with an emphasis on methods to assay single cells for neurotransmitters and neuromodulators that do not require analyte preselection. Current capabilities of capillary-based microseparations and mass spectrometry are highlighted for this application. Methods to combine multiple analytical techniques to provide chemical, spatial and temporal information are described.     

Intramolecular palladium mediated π-allyl cyclisation of bis-Cbz- and bis-Boc-protected guanidines

The Pd-mediated π-allyl cyclisation of bis-Cbz- and bis-Boc-protected guanidines 4 and 14b led to the formation of five- and six-membered heterocycles 5 and 17 in high yields.     

Visible-light Photochemistry and Phototoxicity of Thiarubrines

Abstract. Thiarubrines, a group of intensely red, sulfur-containing pigments produced by asteraceous plants, are photola-bile, yielding thiophenes and elemental sulfur upon exposure to UV or visible light. The mechanism of this light-induced conversion for thiarubrines A (la), B (lb) and D (lc), isolated from the roots of Ambrosia chamis-sonis (Asteraceae), was investigated. Visible-light irradiation of thiarubrines resulted in the formation of novel 2,6-dithiabicyclo[3.1.0]hex-3-ene polyyne photointerme-diates (photosulfides) that rapidly undergo desulfuriza-tion to yield thiophenes. Six photosulfides, photosulfides 3a and 3a' from thiarubrine A (la), photosulfides 3b and 3b' from thiarubrine B (lb) and photosulfides 3c and 3c' from thiarubrine D (lc) were characterized. Thiarubrine photointermediates are short-lived and unstable, with the photosulfides formed from thiarubrine A having a half-life of 12.3 min at room temperature. While the immediate fate of the extruded sulfur is unknown, we identified cyclooctasulfur (S₈) in photolysis solutions of thiarubrine A using electron impact mass spectrometry. Visible-light irradiation of Candida albicans cell suspensions treated with thiarubrine A led to a 99% decrease in cell viability, suggesting that the photosulfides, or other molecules generated by the exposure of thiarubrines to light, have significant toxicity.