RESUMO
A new chain structure of Au is found on stepped Si(111) which exhibits a 1/4-filled band and a pair of > or =1/2-filled bands with a combined filling of 4/3. Band dispersions and Fermi surfaces for Si(553)-Au are obtained by photoemission and compared to that of Si(557)-Au. The dimensionality of both systems is determined using a tight binding fit. The fractional band filling makes it possible to preserve metallicity in the presence of strong correlations.
Assuntos
Agonistas alfa-Adrenérgicos/farmacologia , Transtornos Relacionados ao Uso de Opioides/tratamento farmacológico , Agonistas alfa-Adrenérgicos/uso terapêutico , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Clonidina/farmacologia , Clonidina/uso terapêutico , Humanos , Síndrome de Abstinência a Substâncias/metabolismo , Síndrome de Abstinência a Substâncias/patologiaRESUMO
It has been proposed that the Si(557)-Au surface exhibits spin-charge separation in a one-dimensional electron liquid. Two narrowly spaced bands are found which exhibit a well-defined splitting at the Fermi level. That is incompatible with the assignment to a spinon-holon pair in a Luttinger liquid. Instead, we propose that the two bands are associated with two nearly degenerate atomic chains, or a chain of step atoms with two broken bonds. Such an assignment explains why the surface is metallic despite an even number of electrons per unit cell.
RESUMO
The structure of membranes of Salmonella derby cells both containing R-plasmid and free of plasmid was studied by small- and large-angle X-ray diffraction. Reflections with interplane distances of 8 and 11 A were detected, which are typical of plasmid-carrying S. derby cells. These reflections are assumed to be due to equidistant well ordered positions of the polar groups of phosphatidylcholine and phosphatidylethanolamine molecules on membrane surface. It is also suggested that the formation of these structures is determined by peculiar hydrophilic-hydrophobic interactions of the phospholipid in membranes.
