Electromagnetic moments of the beta-emitting nucleus 16N

The nuclear magnetic dipole moment mu and electric quadrupole moment Q of the beta-emitting 16N(Ipi = 2(-), T(1/2) = 7.13 s) nucleus have been determined for the first time by detecting its beta-NMR in a MgO crystal and beta-NQR (nuclear quadrupole resonance) in a TiO (2) crystal to be /mu/ = (1.9859+/-0.0011) mu(N) and /Q/ = (17.9+/-1.7) mb, respectively. Although the prediction of mu given by the Hartree-Fock calculation agrees well with the experiment, an abnormally small effective charge for neutrons is required to account for the experimental Q.     

Synthesis and electrolytic polymerization of the ethylenedioxy-substituted terthiophene-fullerene dyad

[reaction: see text] Two derivatives of ethylenedioxy-substituted terthiophene-fullerene dyads were newly synthesized as the precursors for polythiophene having fullerene side chains. By electrolytic oxidation of dyad 1, the charm-bracelet type polythiophene, poly-1, was obtained as a purple film, which showed electrochemical activity, electrochromism, and photoelectronic response.     

Synthesis of marine sponge bisindole alkaloids dihydrohamacanthins

[structure: see text] A convergent synthesis of the marine sponge bisindole alkaloids dihydrohamacanthins is described. The synthesis centers on the construction of 3,5- and 3,6-linked pyrazinones and their reduction to the requisite piperazinones with sodium cyanoborohydride.     

Excimer emission of crystalline naphthalene

Excimer emission of naphthalene has been observed in microcrystals obtained by grinding single crystals mechanically and in evaporated films. The emission spectrum of the excimer in the microcrystal was equal to that in the evaporated film. The decay times of both excimer emissions were about 140 ns at 77 K. The temperature dependence of these decay times has been interpreted by the distribution of the excimers in thermal equilibrium between two vibrational states.     

A constitutive equation derived from the model of doi and edwards for concentrated polymer solutions and polymer melts

In deriving a constitutive equation from a molecular model of polymers in concentrated solutions and melts, Doi and Edwards used a mathematical approximation, the “independent alignment approximation,” which has recently been shown to produce significant error in the particular case of stress relaxation following a double-step strain in opposite direction. In the present paper, in order to examine the approximation in general cases, we derive a new constitutive equation without using the independent alignment approximation. The new equation is a nonlinear integro-differential equation and is solved numerically for several cases, i.e., steady shear and elongational flows, and the transient flows after the start of shear and elongation. It is found that, in the cases examined here, the new constitutive equation gives nearly the same results as the old one: the rheological functions calculated from the two theories differ no more than 30%. This substantiates the expectation that the independent alignment approximation does not produce drastic error as long as the flow direction is not reversed.     

Denitrohydrogenation of aliphatic nitro compounds and a new use of aliphatic nitro compounds as radical precursors

Aliphatic nitro groups are replaced by hydrogen on treatment with tributyltin hydride which proceeds via free radical chain processes. As the nitro group is selectively denitrated and other reducible groups are not affected with tributyltin hydride, this reaction can be used as a method for removing the nitro group from polyfunctional compounds. The radical intermediates generated via denitration can be also used for the carbon-carbon bond forming reactions.     

A model for structural safety using the extreme value approach

A new method of evaluating the safety of a structure using the maximum mean largest value concept is introduced. The paper is characterized by the following points: The maximum probability of failure is defined by employing the upper bound of load and the lower bound of resistance, that is, the structural safety is evaluated under the worst-state both for load and resistance. This is a distribution-free approach to the concept of structural safety, and the probability of failure is calculated without assuming the probability density distributions of load and resistance. Three new characteristics are introduced so that the character of the data is strongly reflected on the estimation of the maximum probability of failure. A numerical example is given using the test data.