Shift of emission band upon excitation at the long-wavelength absorption edge. Time-dependent fluorescence shift of a fluid ethanol solution of 6-methoxyquinoline

The fluorescence spectrum of 6-methoxyquinoline in fluid ethanol solution at 294 K shifts progressively to the red with time. The results are discussed in connection with the excitation-energy-dependent fluorescence shift previously studied.     

Combined application of auto-correlated (COSY) and homonuclear J-resolved two-dimensional NMR spectra for the assignment of congested,non-first order spectra of polycyclic aromatic systems. Assignment of the 1H-NMR spectrum of benzo[2,3]phenanthro-[4,5-bcd]thiophene and an investigation of long range 1H-1H spin-coupling constants

Total assignment of the proton nmr spectrum of benzo[2,3]phenanthro[4,5-bcd]thiophene at 200 MHz is reported. Preliminary identification of the resonances comprising the individual spin Systems was accomplished by the use of auto-correlated two-dimensional proton nmr spectroscopy (COSY). Individual assignments were made on the basis of spin-coupling information which was obtained from the “titled” two-dimensional J-resolved (2DJ) proton nmr spectrum of the title compound. Because of the greater resolving power of the latter experiment relative to conventional proton nmr spectroscopy, a number of long range inter-ring spincouplings were observed. The observation of these long range couplings was crucial to the final assignment of several of the resonances in the spectrum. Resonances due to strong coupling in the 2DJ spectrum were also shown to be a useful means of correlating strongly coupled spins which provides an alternative to the COSY spectrum for this purpose.     

Semiconductor-mediated oxidative dimerization of 1-naphthols with dioxygen and O-demethylation of the enol-ethers by SnO2 without dioxygen

Oxidative dimerization of 1-naphthols 1 with dioxygen in the presence of a semiconductor, such as SnO₂, ZrO₂, or activated charcoal, as a catalytic mediator takes place selectively to give the corresponding 2,2′-binaphthols 2 or 2,2′-binaphthyl-1,1′-quinones 3 in excellent yields without light irradiation. The catalytic activity of SnO₂ could be fully restored by appropriate reactivation treatment after the oxidation. In addition, SnO₂ without dioxygen catalyzes selective O-demethylation of the enol-ethers 3 to 4.     

Hydrogel formation between enantiomeric B-A-B-type block copolymers of polylactides (PLLA or PDLA: A) and polyoxyethylene (PEG: B); PEG-PLLA-PEG and PEG-PDLA-PEG

A mixed suspension of the enantiomeric B-A-B triblock copolymers, polyoxyethylene-block-poly(L-lactide)-block-polyoxyethylene (PEG-PLLA-PEG) and polyoxyethylene-block-poly(D-lactide)-block-polyoxyethylene (PEG-PDLA-PEG), was found to induce reversible gel-to-sol transition depending on the polymer concentration and temperature. The storage and loss moduli of the gel formed at lower temperature were much higher than those of the gel prepared from the corresponding ABA-type triblock copolymers because of the higher polymer concentration in the former. Although the stereo-complexation of the PLLA and PDLA blocks occurred at higher temperature also in the B-A-B copolymers, it was not responsible for the gelation of the mixed suspension. The PEG chains, involved in the helix formation of the PLLA and PDLA, should form helices with opposite helical senses to aggregate and lead the gelation of the system.     

Some <Emphasis Type="Italic">L</Emphasis>-Function of a Regular Covering of a Graph

Let ₁:KH, ₂:HG and ₂₁:KG be three finite regular coverings of graphs, and let be a representation of the covering transformation group of ₁. We show that the (Bartholdi type) L-function of G associated to the representation of the covering transformation group of ₂₁ induced from is equal to that of H associated to by means of ordinary voltage assignments.Acknowledgments. We would like to thank the referee for many valuable comments and suggestions. This is partially supported by Grant-in-Aid for Science Research (C).Final version received: February 16, 2004     

Observables and quark confinement in the covariant canonical formalism of Yang-Mills theory III

The consequences about the observables in the Yang-Mills theory are summarized and a conclusion is drawn that the theory provides colour confinement on the assumption that every physical state vector can be approximated by localized physical state vectors. In this formalism, a theorem is proved asserting the failure of the cluster property for local non-observable operators contained in a composite local observable. This failure of the cluster property means the mutual strong correlation of unphysical particles separated far away and implies non-applicability of the behind-the-moon argument (usually placed against a confinement) to the present situation.