A synthesis of lumazine derivatives

Treatment of 6-amino-1,3-dimethyl-5-nitrosouracil (Ia) with dimethyl acetylenedicarboxylate (DMAD) in dimethylformamide (DMF) afforded 6,7-bis(dimethoxycarbonyl)-1,3-dimethyllumazine (II). Similarly, the reaction of 6-amino-1,3-dimethyl-5-phenylazouracil with DMAD gave also II. Hydrolysis of II with hydrochloric acid gave 1,3-dimethyllumazine-6-carboxylic acid (III). III was chlorinated with thionyl chloride and then aminated with ethanolic ammonia to give rise to 6-carbamoyl-1,3-dimethyllumazine (V). V was alternatively synthesized by the treatment of Ia with propiolamide in DMF.     

Functional integral representations of the Pauli-Fierz model with spin 1/2

A Feynman-Kac-type formula for a Lévy and an infinite-dimensional Gaussian random process associated with a quantized radiation field is derived. In particular, a functional integral representation of e−tHPF generated by the Pauli-Fierz Hamiltonian with spin 1/2 in non-relativistic quantum electrodynamics is constructed. When no external potential is applied HPF turns translation-invariant and it is decomposed as a direct integral . The functional integral representation of e−tHPF(P) is also given. Although all these Hamiltonians include spin, nevertheless the kernels obtained for the path measures are scalar rather than matrix expressions. As an application of the functional integral representations energy comparison inequalities are derived.     

On singularities arising from the contraction op the minimal section of a ruled surface

We will discuss the Gorenstein property of the singularity which is blown down from the minimal section of a ruled surface in terms of the extension class. In the case that the base field has positive characteristic, we find a new example (3.4) of Gorenstein singularity in connection with Theorem B.     

Spirostane derivatives highly oxygenated at A and B rings from the rhizomes of rohdeajaponica roth and of campylandra aurantiaca baker

Two steroidal compounds BR-1 (I) and ?2 (II) which had been obtained from the rhizomes of $\text{Campylandra aurantiaca}$ Baker, were isolated also from those of $\text{Rohdea japonica}$ Roth. They were identified, respectively, by X-ray analysis and chemical correlation as 1β,2β,3β,4β,5β,7α-hydroxy-spirost-25(27)-en-6-one and its corresponding 6β-hydroxy compound.     

QUANTUM EFFICIENCY FOR THE PHOTOCONVERSION OF BACTERIORHODOPSIN AT VERY LOW TEMPERATURES

Abstract— Quantum efficiencies for photoconversion of bacteriorhodopsin (trans-bR) to a bathochromic product (batho-bR^t) and its photoreversion in purple membrane at 77 and 9 K were investigated with low temperature spectrophotometry. The kinetics of the photoconversion and its photoreversion cannot be expressed by a single exponential curve. The photoconversions at 77 and 9 K showed the same slope in the early stage. The kinetics of the photoreversions were identical at the two temperatures. These results indicate that the quantum efficiencies for the conversion of trans-bR to batho-bR^t or for its photoreversion are identical at the two temperatures.
The fact that the photoreversion cannot be expressed by a single exponential curve suggests the existence of several conformational states of batho-bR^t due to the trimer structure of the purple membrane.     

Interpolation error estimates of a modified 8-node serendipity finite element

Summary. Interpolation error estimates for a modified 8-node serendipity finite element are derived in both regular and degenerate cases, the latter of which includes the case when the element is of triangular shape. For defined over a quadrilateral K, the error for the interpolant is estimated as , where in the regular case and in the degenerate case, respectively. Thus, the obtained error estimate in the degenerate case is of the same quality as in the regular case at least for . Results for some related elements are also given. Received June 2, 1997 / Published online March 16, 2000     

Thickness and hole-shape dependence of flux penetration into square superconducting networks

We have observed flux penetrations into square superconducting networks of Nb with various thicknesses and hole-shapes by using magneto-optical imaging method. The penetrated pattern does not depend on the thickness and extends along diagonal direction when the samples have smaller area in the intersection of networks. We have also observed similar superconducting networks with and without small holes at the intersection. The small holes at the intersection do not work as a promoter for the diagonal flux penetration though the parallel flux penetration becomes weak. We discuss possible origins of these anomalous anisotropic flux penetrations.     

Enhancement of Mn red emission in CaGa2S4 compounds by co-doping rare-earth elements

When certain trivalent rare-earth ions (Ln's) are co-doped in CaGa₂S₄:Mn²⁺ as sensitizers, the Mn red emission of the compound is strikingly enhanced. In this work, efficiency of each lanthanide is studied. The best efficiencies are achieved with La³⁺-, Pr³⁺-, and Tb³⁺- co-doped compounds, for each of which the effects of concentrations of the co-doped ions on the Mn²⁺ emission are investigated. The energy-transfer mechanisms and the location of electronic energy levels of both the trivalent and the divalent lanthanides in the energy band gap of the host material are discussed. Depending on Ln's, charge transfer or cross-relaxation should be taken into account.