Observational Results of Stellar Speckle Interferometric Spectroscopy

Stellar speckle spectroscopy is a speckle interferometric method enabling us to separate point by point spectra on a stellar object with a diffraction-limited spatial resolution of a telescope. We describe observational results obtained with our system for speckle spectroscopy. Data of two binary stars, of which separations are closer than seeing disc, were taken and processed by cross-correlation method. In each object, spectral images of two component stars around the Hα line (656.3 nm) were spatially resolved with nearly diffraction-limited resolution. The separated spectra of ADS940 reveal different spectral types of the component stars. These results demonstrate the ability of the speckle spectroscopic method.Presented at the International Commission of Optics Topical Meeting, Kyoto, 1994.     

Synthesis of unsymmetrically substituted 2,5-piperazinediones: regioselective alkylation of piperazinedione derivatives

A variety of unsymmetrically substituted 2,5-piperazinediones have been synthesized by regioselective alkylation of piperazinedione derivatives.     

On the chaotic nature of turbulence observed in benchmark analysis of nonlinear plasma simulation

Simulational results of two dissipative interchange turbulence (Rayleigh-Taylor-type instability with dissipation) models with the same physics are compared. The convective nonlinearity is the nonlinear mechanism in the models. They are shown to have different time evolutions in the nonlinear phase due to the different initial value which is attributed to the initial noise. In the first model (A), a single pressure representing the sum of the ion and electron components is used (one-fluid model). In the second model (B) the ion and electron components of the pressure fields are independently solved (two-fluid model). Both models become physically identical if we set ion and electron pressure fields to be equal in the model (B). The initial conditions only differ by the infinitesimally small initial noise due to the roundoff errors which comes from the finite difference but not the differentiation. This noise grows in accordance with the nonlinear development of the turbulence mode. Interaction with an intrinsic nonlinearity of the system makes the noise grow, whose contribution becomes almost the same magnitude of the fluctuation itself in the results. The instantaneous deviation shows the chaotic characteristics of the turbulence. (c) 1997 American Institute of Physics.     

New labdane diterpenoids from Hyptis fasciculata

Two new labdane diterpenoids, 15beta-methoxyfaciculatin (1) and 15alpha-methoxyfaciculatin B (2), together with the previously known methoxynepetaefolin (3), were isolated from a methanol extract of the dried aerial parts of a Brazilian medicinal plant, Hyptis faciculata. Their structures were elucidated by analysis of spectroscopic data. Plausible biogenetic correlation between faciculatins and nepetaefolin is briefly discussed.     

Determination of naturalα-radionuclides related to millisecond order lives in environmental samples using the time interval analysis (TIA) method

The time files due to radioactive decay events were analyzed for the selective extraction of successive alpha-decay pulse events in millisecond orders, such as²¹⁶Po (145 ms, thorium series),²¹⁷At (32.3 ms, neptunium series), and²¹⁵Po (1.78 ms, actinium series) after respective preceding parents decay, using a multiple time interval analysis (TIA-MTA) technique from both theoretical and experimental viewpoints. In the theoretical treatments, the detection sensitivities of each correlated event in natural decay series was compared with more generalized conditions. It was noteworthy that the evaluated detection sensitivity had increased proportionally with shorter half-lives in the following order:²¹⁴Po>²¹⁵Po>²¹⁷At>²¹⁶Po.Finally, the present TIA was applied to the clarification of thorium series disequilibrium states in Tamagawa (Akita, Japan) Hot Spring waters. Activities of²²⁴Ra were evaluated to be 3.41±0.38 and 0.60±0.08 Bq/l at the upper and lower stream, respectively. The results from activity ratios of radium to thorium isotopes showed a preferential precipitation of radium isotopes in comparison with thorium, reflecting the sensitivity to the lowering acidity of strongly acidic hot spring waters in the lower end of the stream.     

Synthetic approaches toward mitomycins. I. Stereoselective synthesis of a tetracyclic intermediate.

A highly efficient synthesis of a tetracyclic intermediate to the antitumor antibiotics AX-2 , mitomycin A , and C is described.     

Enantioselective total synthesis of aspidophytine

[structure: see text] An enantioselective total synthesis of aspidophytine is described. The indole fragment bearing a cis-alkene substituent was efficiently prepared through radical cyclization of a 2-alkenylphenylisocyanide followed by Sonogashira coupling of the generated 2-iodoindole derivative with a functionalized acetylene unit. After formation of the 11-membered cyclic amine, the aspidosperma skeleton and lactone ring were constructed to complete the total synthesis.