Proton-neutron quasiparticle RPA with separable Gamow-Teller forces

A comprehensive representation is presented of a generalized form of the proton-neutron quasiparticle RPA model, originally introduced by Halbleib and Sorensen almost thirty years ago. The model uses separable Gamow-Teller forces, including, in addition to the particle-hole force of the former model, the particle-particle force, which is of decisive importance for β⁺ decay andββ decay. The above model has further been extended to the treatment of odd-odd nuclei. An extension is also made to transitions from nuclear excited states. This is essential for calculations of nuclear weak transition rates in the high-temperature interior of massive stars. Complementing the discussion of Halbleib and Sorensen on the particle-hole force, the structure of the RPA dispersion relation is discussed with emphasis on effects of the particle-particle force.     

Application of a fast neutron activation method to the determination of oxygen in iron and steel

The determination of oxygen (0.001–0.2%) in iron and steel by the fast neutron activation method was investigated. The relative standard deviations of the method at oxygen levels of 0.1, 0.01, and 0.001%, were 3, 5, and 30%, respectively. The analytical results of the method were in good agreement with those of the conventional method in the range stated.     

rel-(1R,4R,5S)-5-hydroxy-3-oxo-2-azabicyclo[2.2.0]hexane,a stable synthetic equivalent of 4-(2-oxoethyl)azetidin-2-one

The title compound, a synthetic equivalent of 4-(2-oxoethyl)-azetidin-2-one, has been synthesized as a stable crystalline solid either from 4-($\text{t}$-butyldimethylsilyloxy)- or 4-benzyloxy-2-pyridone $\text{via}$ photopyridone formation, catalytic hydrogenation, and deblocking of the protecting group.     

Ultrasonic attenuation measurements in ErRh4B4 near 1 K

Ultrasonic attenuation measurements on a polycrystalline specimen of ErRh₄B₄ near 1° K and in magnetic fields up to 14 kOe are reported. A broad peak in zero-field attenuation is observed near T_c2, the temperature at which ferromagnetic order appears. At large magnetic fields ( > H_c2) a larger attenuation is observed when the propagation vector of the sound wave is perpendicular to the field direction than when it is parallel. The interpretation of these results is discussed.     

Agelasine-A, -B, -C and -D,novel bicyclic diterpenoids with a 9-methyladeninium unit possessing inhibitory effects on na,K-atpase from the okinawa sea sponge Agelas sp.1)

Agelasine-A, -B, -C and -D, novel bicyclic diterpenoids having inhibitory effects on enzymic reactions of Na,K-ATPase, have been isolated from the orange colored Okinawan sea sponge $\text{Agelas}$ sp. and the structures have been determined on the basis of their spectral data and chemical conversions.     

Scalar and vector meson propagation in asymmetric nuclear matter

The propagation of the scalar (σ and δ) and vector (ω and ρ) mesons in an iso-asymmetric nuclear matter is studied in detail, using the Walecka model. We calculate the invariant masses and spectral functions of the mesons, including the effect of meson mixing. At finite density, the mixing effect is quite important in the propagation of the scalar and (longitudinal) vector mesons. In the σ channel, we find a three-peak structure in the spectral function, caused by the mixing effect.     

Kaon-condensed hypernuclei as highly dense self-bound objects

The structure of K⁻-condensed hypernuclei, which may be produced in the laboratory in strangeness-conserving processes, is investigated using an effective chiral Lagrangian for the kaon–baryon interaction, combined with a nonrelativistic baryon–baryon interaction model. It is shown that a large value of negative strangeness is needed for the formation of highly dense and deeply bound state with kaon condensates and that part of the strangeness should be carried by hyperons mixed in the nucleus. The properties of kaon-condensed hypernuclei such as the ground state energy and particle composition are discussed. Such a self-bound object has a long lifetime and may decay only through weak interaction processes. Comparison with other possible nuclear states is also made, such as kaon-condensed nuclei without mixing of hyperons and noncondensed multistrange hypernuclei. Implications of kaon-condensed hypernuclei for experiments are mentioned.     

Total Synthesis and Structure Revision of Didemnaketal B

Didemnaketal B, a structurally complex spiroacetal that exhibits potent HIV‐1 protease inhibitory activity, was originally discovered by Faulkner and his colleagues from the ascidian Didemnum sp. collected at Palau. Its absolute configuration was proposed on the basis of degradation/derivatization experiments of the authentic sample. However, our total synthesis of the proposed structure of didemnaketal B questioned the stereochemical assignment made by Faulkner et al. Here we describe in detail our first total synthesis of the proposed structure 2 of didemnaketal B, which features 1) a convergent synthesis of the C7–C21 spiroacetal domain by means of a strategy exploiting Suzuki–Miyaura coupling, 2) an Evans syn‐aldol reaction and a vinylogous Mukaiyama aldol reaction for the assembly of the C1–C7 acyclic domain, and 3) a Nozaki–Hiyama–Kishi reaction for the construction of the C21–C28 side chain domain. The NMR spectroscopic discrepancies observed between synthetic 2 and the authentic sample as well as careful inspection of the Faulkner’s stereochemical assignment led us to postulate that the absolute configuration of the C10–C20 domain of 2 has been erroneously assigned. Accordingly, the total synthesis of the revised structure 65 was achieved to show that the NMR spectroscopic properties of synthetic 65 were in good agreement with those of the authentic sample. Furthermore, application of the phenylglycine methyl ester (PGME) method to the C7–C21 spiroacetal domain enabled us to establish the absolute configuration of didemnaketal B.