No abstract

To be published in the Journal of the Korean Physical Society) Momentum-dependent excitation spectra of the two-dimensional Hubbard model on the square lattice have been investigated at zero temperature on the basis of the full self-consistent projection operator method in order to clarify nonlocal effects of electron correlations on the spectra. It is found that intersite antiferromagnetic correlations cause shadow bands and enhance the Mott-Hubbard splittings near the half-filling. Furthermore nonlocal excitations are shown to move the critical doping concentration δ * h , at which the singular quasiparticle peak is located just on the Fermi level, from δ * h = 0.153 (the single-site value) to δ * h = 0.123. The latter suggests the occurance of an instability such as the stripe at δ * h = 1/8.

The chloroform and methanol extracts of seed and seed coat of Caesalpinia bonduc L., Mucuna pruriens L., Adenanthera pavonina L., Terminalia bellirica Geatn., Syzygium cumini L.

Abstract:The chloroform and methanolic extracts of seed coat and seed kernel of Mucuna pruriens, Terminalia. bellirica, Syzygium cumini and Myristica fragrans were tested against the brine shrimp, Artemia fransiscana nauplii for mortality at 24h post exposure. All the test extracts were found to be effective. The toxicity of the chloroform extracts of seed coat could be arranged in the order: