Total synthesis of (+/-)-alpha- and beta-lycoranes by sequential chemoselective conjugate addition-stereoselective nitro-Michael cyclization of an omega-nitro-alpha,beta,psi,omega-unsaturated ester

[reaction: see text] An omega-nitro-alpha,beta,psi,omega-unsaturated ester underwent a chemoselective conjugate addition of a nitroolefin moiety with aryllithium to produce a psi-aryl-omega-nitro-alpha,beta-unsaturated ester, which was then stereoselectively cyclized by intramolecular nitro-Michael reaction giving a functionalized cyclohexane applicable to the total synthesis of (+/-)-alpha- and beta-lycoranes.     

Characterization of the mod 3 cohomology of

It is shown that the mod 3 cohomology of a homotopy associative mod 3 -space which is rationally equivalent to the Lie group and which has integral 3-torsion is isomorphic to that of as a Hopf algebra over the mod 3 Steenrod algebra.

     

On a Lift of an Individual Stable Equivalence to a Standard Derived Equivalence for Representation-Finite Self-injective Algebras

We shall show that every stable equivalence (functor) between representation-finite self-injective algebras not of type (D _3m ,s/3,1) with m2, 3s lifts to a standard derived equivalence. This implies that all stable equivalences between these algebras are of Morita type.     

The first Bianchi identity in synthetic differential geometry

We give a synthetic treatment of the first Bianchi identity both in the style of differential forms and in the style of tensor fields on the lines of Lavendhomme (Basic Concepts of Synthetic Differential Geometry, Kluwer, Dordrecht, 1996). The tensor-field version of the identity is derived from the corresponding one for microcubes, just as we did for the Jacobi identity of vector fields with respect to Lie brackets in our previous paper (J. Theoret. Phys. 36 (1997) 1099–1131). As a by-product we have found out an identity of microcubes corresponding to the classical identity

R(X,Y,Z)=_XYZ−_YXZ−_[X,Y]Z

of tensor fields, which has largely simplified Lavendhomme's lengthy proof (Basic Concepts of Synthetic Differential Geometry, Kluwer, Dordrecht, 1996, Section 5.3, Proposition 8, pp. 176–180).     

Reduction of ion thermal diffusivity associated with the transition of the radial electric field in neutral-beam-heated plasmas in the large helical device

Recent large helical device experiments revealed that the transition from ion root to electron root occurred for the first time in neutral-beam-heated discharges, where no nonthermal electrons exist. The measured values of the radial electric field were found to be in qualitative agreement with those estimated by neoclassical theory. A clear reduction of ion thermal diffusivity was observed after the mode transition from ion root to electron root as predicted by neoclassical theory when the neoclassical ion loss is more dominant than the anomalous ion loss.     

Observation of the "self-healing" of an error field island in the large helical device

It was observed that the vacuum magnetic island produced by an external error magnetic field in the large helical device shrank in the presence of plasma. This was evidenced by the disappearance of flat regions in the electron temperature profile obtained by Thomson scattering. This island behavior depended on the magnetic configuration in which the plasmas were produced.     

Supersmooth Topoi

It is well known that supersmooth functions are more akin to holomorphicfunctions than to smooth functions. The ultimate object of study in complexgeometry is not merely complex manifolds, but complex spaces, in whichholomorphic functions may be nilpotent and consequently invisible from ageometric viewpoint. Supergeometers have long been searching for an appropriatedefinition of supermanifold, for which many classical results in the theory ofsmooth manifolds can naturally be superized. However, they have not proceededfurther in quest of a supersmooth equivalent of complex space. The principalobject of this paper is to introduce the notion of supersmooth superspace intosupergeometry after the classical definition of complex space in complexgeometry, and then to build a good model of synthetic supergeometry after themanner of Dubuc and Taubin (1983), thereby superseding Yetter (1988). Themodel to be constructed is a Grothendieck topos encompassing the category ofG -supermanifolds and G -mappings as a full subcategory.     

Observation of direct photons in central 158A GeV (208)P(208)b+Pb collisions

A measurement of direct photon production in 208Pb+208Pb collisions at 158A GeV has been carried out in the CERN WA98 experiment. The invariant yield of direct photons in central collisions is extracted as a function of transverse momentum in the interval 0.51.5 GeV/c. The result constitutes the first observation of direct photons in ultrarelativistic heavy-ion collisions. It could be significant for diagnosis of quark-gluon-plasma formation.     

Improved surface morphology of flow-modulated MOVPE grown AIN on sapphire using thin medium-temperature AIN buffer layer

High-temperature (HT) AIN films were grown on (0 0 0 1) sapphire by low-pressure flow-modulated (FM) metal organic vapor phase epitaxy (MOVPE) with and without inserting a thin medium-temperature (MT) AIN layer. To suppress parasitic reactions between the sources of trimethylaluminum (TMA) and ammonia (NH₃), TMA and NH₃ was introduced to the reactor of MOVPE by alternating supply way. Surface morphology and crystalline quality were characterized by a scanning electronic microscopy (SEM), atomic force microscopy (AFM) and X-ray rocking curve (XRC) measurements of (0 0 0 2) and (10-12) diffractions. The AFM and SEM measurements indicated that the thin MT-AIN layer had a strong influence on the surface morphology of the HT-AIN films. The surface morphology became quite smooth by inserting the thin MT-AIN layer and surface RMS roughness values were 0.84 nm and 13.4 nm for the HT-AIN films with and without inserting the thin MT-AIN buffer layer, respectively. By etching the samples in aqueous KOH solution, it was found that the polarity of AIN films was different, the HT-AIN film with the thin MT-AIN layer could not be etched, indicating that the film had an Al-polar surface; however, the film without the MT-AIN layer was etched, which was explained that that film had a N- or mixed-polar surface. The mechanism for the origin of the different polarity of HT-AIN with and without the thin MT-AIN layer was proposed and discussed in detail.     

Electronic structure of substitutional nitrogen impurity in TiO 2 studied by the β-NMR method

In order to study the local electronic structure of nitrogen impurity in rutile TiO₂, we have measured double-quantum NMR spectra of short lived β-emitter ¹²N(I = 1, T _1/2 = 11 ms) implanted into a rutile single crystal by means of the β-NMR technique. The resonance line obtained at room temperature is well accounted for by the second order shift due to the quadrupole interaction at the oxygen substitutional site. The spectrum at 25 K has shown the other lines than the central diamagnetic line shifted by 10?15 kHz to both sides, which has been already shown in the previous data obtained with a different crystal orientation and an external field. The present results supports the existence of a paramagnetic state formed by the substitutional nitrogen impurities.