8 research outputs found
Imaging the Fano Lattice to 'Hidden Order' Transition in URu2Si2
Within a Kondo lattice, the strong hybridization between electrons localized
in real space (r-space) and those delocalized in momentum-space (k-space)
generates exotic electronic states called 'heavy fermions'. In URu2Si2 these
effects begin at temperatures around 55K but they are suddenly altered by an
unidentified electronic phase transition at To = 17.5 K. Whether this is
conventional ordering of the k-space states, or a change in the hybridization
of the r-space states at each U atom, is unknown. Here we use spectroscopic
imaging scanning tunnelling microscopy (SI-STM) to image the evolution of
URuSi2 electronic structure simultaneously in r-space and k-space. Above To,
the 'Fano lattice' electronic structure predicted for Kondo screening of a
magnetic lattice is revealed. Below To, a partial energy gap without any
associated density-wave signatures emerges from this Fano lattice.
Heavy-quasiparticle interference imaging within this gap reveals its cause as
the rapid splitting below To of a light k-space band into two new heavy fermion
bands. Thus, the URu2Si2 'hidden order' state emerges directly from the Fano
lattice electronic structure and exhibits characteristics, not of a
conventional density wave, but of sudden alterations in both the hybridization
at each U atom and the associated heavy fermion states.Comment: Main Article + Supplementary Informatio
Role of nitric oxide in tumor angiogenesis
Nitric oxide (NO) is an important signalling molecule that acts in many tissues to regulate different physiological and pathological processes. We have contributed to demonstrate that NO stimulates angiogenesis and mediates the effect of different angiogenic molecules. In human tumors NOS expression and activity correlate with tumor growth and aggressiveness, through angiogenesis stimulation and regulation of angiogenic factor expression. Drugs affecting the NOS pathway appear promising antitumor strategies by reducing edema, inhibiting angiogenesis and facilitating the delivery of chemotherapeutical agents