alpha-Aminoallylation of aldehydes in aqueous ammonia

alpha-Aminoallylation of aldehydes in aqueous ammonia has been developed; commercial aqueous ammonia was successfully used, and this method does not require anhydrous conditions thus leading to easy and practical operations.     

Evidence of complete fusion in the subbarrier 16O+238U reaction

Evaporation residue cross sections in the ¹⁶O+²³⁸U reaction were measured for the energy range from above-to extreme subbarrier. We used a He-gas-jet system to transport the fusion products, and the α decay of the evaporation residues was measured by using a rotating wheel system. The measured cross sections for ^248,249,250Fm are reproduced by a statistical model calculation, for which partial cross sections are calculated by a coupled-channel model taking into account the prolate deformation of ²³⁸U. We conclude that complete fusion is the main process in the subbarrier energy region, and quasifission is not an important channel. The text was submitted by the authors in English. On leave from China Institute of Atomic Energy, Beijing, China.     

Effect of freeze-thawing and polyethylene glycol (PEG) lipid on fusion and fission of phospholipid vesicles

The effect of freeze-thawing on the size of egg yolk phosphatidylcholine (EggPC) vesicles in the presence of 0-40 mol% distearoylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG) was studied. Mean diameters of the vesicles fell into a range of 80-150 nm after 10 times freeze-thawing in spite of their original size. In the process of freeze-thawing, two opponent events, one is fission and the other is fusion, occurred at the same time. DSPE-PEG accelerated the fusion event.     

The structure of a real linear combination of two projections

A necessary and sufficient condition for a Hermitian operator on a Hilbert space to be expressed as aP + bQ with some projections P, Q and reals a, b is established. Moreover the spectrum of such an operator is explicitly drawn in terms of the spectrum of PQ ∣ran P, the restriction to the range of P.     

An air-stable,storable chiral zirconium catalyst for asymmetric aldol reactions

Asymmetric aldol reactions of ketene silyl acetals with aldehydes using an air-stable, storable chiral zirconium catalyst, which could be stored for at least 13 weeks at room temperature, proceeded smoothly to afford the desired adducts in high yields with high selectivity.     

Effect of nuclear shell structure on fusion reaction

The dependence of the fusion reaction on the nuclear shell structure was investigated for the two reaction systems ⁸²Se + ¹³⁸Ba and ⁸²Se + ¹³⁴Ba, where the nucleus ¹³⁸Ba has a closed neutron shell N=82, while the nucleus ¹³⁴Ba has a neutron number 78. Evaporation residues for these fusion reactions were measured near the Coulomb barrier region. The measured evaporation residue cross sections for the reaction system ⁸²Se + ¹³⁸Ba were two orders of magnitude larger than those for the reaction system ⁸²Se + ¹³⁴Ba in the excitation energy region of 20–30 MeV. The evaporation residue cross sections were compared with those of the other reaction systems that produce the same compound nucleus as the present systems. It was found that the fusion reaction ⁸²Se + ¹³⁸Ba occurs without hindrance, while that of ⁸²Se + ¹³⁴Ba is considerably hindered, as commonly observed in the massive reaction system with the charge product Z _p Z _t >1800 of projectile and target. This suggests the importance of the shell closure N=82 in the heavy-ion fusion reaction.     

Discrete spectra of -algebras and complemented submodules in Hilbert -modules

Let be a -algebra and let be a full (right) Hilbert -module. It is shown that if the spectrum of is discrete, then every closed --submodule of is complemented in , and conversely that if is a -space and if every closed --submodule of is complemented in , then is discrete.

     

A facile route to 4,5,6,7-tetrahydrothiophenes and benzothiophenes

2-Substituted tetrahydro- and cyclopentathiophenes 2 were produced in high yields by treatment of the semi-cyclic trisubstituted 1,4-diketones 1 such as 2-phenacylcyclohexan-1-one, 2-acetonylcyclohexan-1-one, and 2-phenacylcyclopentan-1-one, with Lawesson's reagent.