Time-resolved ESR study of the lowest excited triplet states of para-quinones in glassy matrices at 77 k

The lowest excited nπ* triplet of 9.10-anthraquinone, 1.4-naphthoquinone and 1,4-benzoquinone were studied in glassy matrices at 77 K using a time-resolved ESR method. The D value of the triplet state of 9,10-anthraquinone varied from ?0.351 cm^?1 in a polar solvent to ?0.318 cm^?1 in a non-polar solvent. Both 1,4-naphthoquinone and 1,4-benzoquinone in polar solvents showed triplet state spectra with a D value of ?0.330 cm^?1. A computer simulation revealed the existence of widely distributed zero-field splitting parameters in the glassy condition. These data are compared with an analysis of CIDEP results of para-quinones.     

The primary fragmentation step of isoxazole upon electron impact. A correlation with photochemistry

Three isomeric compounds, I, II and III, were prepared and their mass spectra recorded. Comparisons of the spectra showed that the fragmentation of I proceeds only by way of II, and that II itself is transformed in part to III upon electron impact. It is suggested that selective ionization of each one of the two isolated functional groups in II may afford two isomeric radical ions, IIa and IIb. A possible interrelation to the photochemistry of these compounds is also discussed.     

A peptide motif recognizing a polymer stereoregularity

A combinatorial phage display method was applied to films composed of a stereoregular polymer of methacrylates. The phage clones with selective affinity for isotactic (it) poly(methyl methacrylate) (PMMA) were isolated. Greater amounts of the phage clones bound to it-PMMA, compared to other stereoregular PMMAs. The phage expressing ELWRPTR most strongly bound to the polymer, and the selectivity was also the best. The peptide motif essential for the specific interaction with the stereoregular polymer was revealed.     

The structure of aureothin, a nitro compound obtained from Streptomyces thioluteus

The structure of aureothin, the third nitro compound obtained from nature, has been elucidated as I. Several reactions of aureothin and its derivatives are described.     

Beta-ray angular distribution in aligned 12B and 12N and G-parity irregular induced tensor current

We made an explicit formula for beta-ray angular distribution by taking into account the radiative corrections, Coulomb corrections of the finite-size nucleus, weak magnetism, induced pseudoscalar, second-class induced tensor, and contributions of the d-wave leptons. Experimental data on the beta decays of aligned ¹²B and ¹²N given at Osaka are carefully investigated, and it is shown that these data are compatible with no induced tensor current, $\text{?}{}_{\mathrm{T}}\text{?}{}_{\mathrm{A}}\text{=}\text{?(0.44 +-0.88)}\text{2M}$. The nuclear parameter y is 3.3±0.9 in excellent agreement with the predicted value 3.6.     

Unicité de la solution de l'équation monodimensionnelle ou à symétrie sphérique d'un gaz visqueux et calorifère

In questo articolo dimostriamo l'unicità della soluzione (globale in tempo) dell'equazione monodimensionale o a simmetria sferica di un gas viscoso e termoconduttore con la superficie libera. In questo risultato il limite inferiore della densità ρ può essere uguale a 0. Assieme al teorema di esistenza dimostrato nei lavori precedenti, costituisce il teorema di esistenza e di unicità (globale in tempo) per questa equazione.     

Negative normal restitution coefficient found in simulation of nanocluster collisions

The oblique impacts of nanoclusters are studied theoretically and by means of molecular dynamics. In simulations we explore two models--Lennard-Jones clusters and particles with covalently bonded atoms. In contrast with the case of macroscopic bodies, the standard definition of the normal restitution coefficient yields for this coefficient negative values for oblique collisions of nanoclusters. We explain this effect and propose a proper definition of the restitution coefficient which is always positive. We develop a theory of an oblique impact based on a continuum model of particles. A surprisingly good agreement between the macroscopic theory and simulations leads to the conclusion that macroscopic concepts of elasticity, bulk viscosity, and surface tension remain valid for nanoparticles of a few hundred atoms.