Spectroscopy of exotic 121, 123, 125Ag produced in fragmentation reactions

Excited states in the neutron-rich ^{121, 123, 125}Ag were studied via the fragmentation of a ¹³⁶Xe beam at 120MeV/nucleon in a thick ⁹Be target. The levels in ¹²¹Ag were populated in the $ \beta$ decay of ¹²¹Pd while those assigned to ^{123, 125}Ag were identified via isomer spectroscopy. The transitions identified in ¹²¹Ag are consistent with the $ \gamma$ -rays reported in ^{117, 119}Ag . The newly observed transitions were placed in the level schemes of ^{123, 125}Ag based on the analysis of $ \gamma$ - $ \gamma$ coincidences and the systematics. We attribute the onset of isomerism in the ^{123, 125}Ag isotopes to the drop in energy of the negative-parity levels similar to the 5^- state in the even-even Cd cores. The proposed level scheme for ¹²⁵Ag is well described by the NuShellX shell model calculations.     

Quasi-interpolatory refinable functions and construction of biorthogonal wavelet systems

We present a new family of compactly supported and symmetric biorthogonal wavelet systems. Each refinement mask in this family has tension parameter ω. When ω = 0, it becomes the minimal length biorthogonal Coifman wavelet system (Wei et al., IEEE Trans Image Proc 7:1000–1013, 1998). Choosing ω away from zero, we can get better smoothness of the refinable functions at the expense of slightly larger support. Though the construction of the new biorthogonal wavelet systems, in fact, starts from a new class of quasi-interpolatory subdivision schemes, we find that the refinement masks accidently coincide with the ones by Cohen et al. (Comm Pure Appl Math 45:485–560, 1992, §6.C) (or Daubechies 1992, §8.3.5), which are designed for the purpose of generating biorthogonal wavelets close to orthonormal cases. However, the corresponding mathematical analysis is yet to be provided. In this study, we highlight the connection between the quasi-interpolatory subdivision schemes and the masks by Cohen, Daubechies and Feauveau, and then we study the fundamental properties of the new biorthogonal wavelet systems such as regularity, stability, linear independence and accuracy.     

Pipe lagging—an effective method of noise control?

There is a lack of reliable information on the application and performance of pipe lagging, even though this method of noise control is widely used to reduce noise radiating from exposed pipework.To provide this information a thorough investigation has been run on piple lagging materials. The noise-reducing properties of over 120 combinations of material were evaluated.Results from this study show that lagging can be a very good form of noise control, provided it is correctly applied. Both inner layer and outer cover contribute to the overall performance. This paper explains how each element contributes to the performance and discusses the effects of material properties on these contributions.The factors limiting the performance of lagging in practical situations are shown to be poor fitting, exposed flanges and physical coupling between the outer cover and the pipe.Performance figures for commonly used laggings are of particular interest. Measured values for mineral wool with various outer covers are included for this reason.     

Molecular aggregation of disklike benzenetricarboxamides containing diacetylenic groups in bulk and organic solvents

We prepared disklike tris(4-alkylbutadiynylphenyl)-1,3,5-benzenetricarboxamide and tris[4-(4-alkyloxyphenyl)butadiynylphenyl]-1,3,5-benzenetricarboxamide, where three phenyl diacetylenic and diphenyl diacetylenic groups are connected to a benzene ring through amide linkages, respectively. The structures of self-assembled substances were investigated by using transmission electron microscopy, scanning electron microscopy, and X-ray diffraction techniques. All the compounds were highly viscous in melt states, and only compound 9 having three phenyl diacetylenic groups and hexyl tails showed a thermotropic mesophase on cooling. The compound with three diphenyl diacetylenic groups and dodecyloxy tails (13) formed a stable gel in THF/cyclohexane. The IR and X-ray analyses showed that in the gel state molecules were assembled into a rectangular columnar lattice and held each other by hydrogen bondings between amide groups. The compound with tetradecyloxy tails (14) formed stable colloidal particles in cyclohexane. The UV irradiation of 13 in a gel and 14 in a colloidal particle did not result in a long conjugated polymer because of the inappropriate alignment of diacetylenic groups for the topochemical polymerization.     

A chemoenzymatic total synthesis of the undecenolide (-)-cladospolide B via a mid-stage ring-closing metathesis and a late-stage photo-rearrangement of the E-isomer

A sixteen-step synthesis of the twelve-membered macrolide (-)-cladospolide B(2) from the microbially-derived cis-1,2-dihydrocatechol 5 is described. Pivotal steps include the ring-closing metathesis (RCM) of diene 12 to give the ten-membered lactone 13 together with small amounts of the head-to-tail and head-to-head dimers 14 and 15, respectively. The saturated lactol 19 derived from compounds 13 and 14 readily participates in a Wadsworth-Horner-Emmons reaction to give the E-configured alpha,beta-unsaturated ester 20. This last compound is then converted, through application of a Yamaguchi lactonisation reaction on the derived acid 22, into the macrolide 23 which, upon removal of the bis-acetal protecting group, affords compound 24, the E-isomer of target 2. Irradiation of a benzene solution of compound 24 results in its partial photoisomerisation to (-)-cladospolide B(2).     

Synthesis and nonlinear optical properties of 1,3,5-methoxy-2,4,6-tris(styryl)benzene derivatives

[reaction: see text] Novel two-dimensional octupoles containing donors at the core and acceptors at the edge of peripheral groups were synthesized by Horner-Wittig reactions. These chromophores show very large first hyperpolarizability and good thermal stability and are attractive candidates for nonlinear optical materials.     

Synthesis of 4-arylidenecyclohexane-1,3-diones from the Baylis-Hillman acetates

Synthesis of 4-arylidenecyclohexane-1,3-dione derivatives was carried out from the Baylis-Hillman acetates. The potential utility of the prepared compounds for the synthesis of cyclohexanedione oxime ether herbicides was examined.     

Statistical mechanical transformation theory for quantum systems with discrete spectra

The superoperator transformation theory developed by the Brussels school is applied to quantum systems with discrete spectra. In the case of nondegeneracy of the spectra, there is no difficulty in obtaining explicit expressions for the most important superoperators in terms of the unitary operator which diagonalizes the Hamiltonian. The degenerate case presents special problems which are studied in detail.     

Heavy-ion reactions on 26Mg

Reactions induced by 126 MeV ¹⁶O ions on ²⁶Mg have been investigated in the angular range 5° to 12°. Optical model parameters were derived from the elastic scattering data and were used in a DWBA analysis of the inelastic scattering and single-nucleon transfer data. Satisfactory agreement was obtained for the angular distributions and for the spectroscopic factors. The two-nucleon transfer reactions appear to excite vibrational states. A DWBA analysis correctly describes the angular distributions for the two-proton transfer data. Most of the other few-nucleon transfer spectra exhibit little selective excitation but give a maximum at an energy consistent with the optimum Q-value predicte for direct transfer. Both the one- and twonucleon transfer data require that the ²⁶Mg ground state contains considerable (λ, μ) = (4. 8) components and is not pure (10, 2) as predicted by simple SU(3) calculations.