We present a spectroscopic study that reveals that the metal-insulator transition of strained VO2 thin films may be driven towards a purely electronic transition, which does not rely on the Peierls dimerization, by the application of mechanical strain. Comparison with a moderately strained system, which does involve the lattice, demonstrates the crossover from Peierls-to Mott-like transitions.
Background: Overexpression of inducible nitric oxide synthase (iNOS) and increased nitric oxide generation may be associated with the hyperdynamic circulation of patients with cirrhosis. We have, for the first time, used the highly selective iNOS inhibitor, 1400W, to determine whether iNOS activity contributes to the regulation of vascular tone in patients with cirrhosis and ascites. Methods: Bilateral forearm blood flow was measured using strain gauge plethysmography in eight patients with cirrhosis and ascites, and eight matched healthy volunteers during intrabrachial infusion of, and norepinephrine (a control vasoconstrictor; 60-480 pmol/min). Results: In patients with cirrhosis, 1400W, L-NMMA, and norepinephrine caused dose dependent reductions in forearm blood flow: peak reductions of 11 (5)%, 37 (4)%, and 48 (5)%, respectively (p,0.05 for all). In contrast, 1400W had no effect on blood flow (+4 (8)%; NS) in healthy controls despite similar reductions in blood flow with L-NMMA and norepinephrine (39 (5)% and 49 (5)%, respectively; p,0.05 for both). Conclusions: We have, for the first time, demonstrated that 1400W causes peripheral vasoconstriction in patients with cirrhosis but not healthy matched controls. This suggests that iNOS contributes to the regulation of peripheral vascular tone in patients with cirrhosis and ascites, and may contribute towards the hyperdynamic circulation associated with this condition.
The topological crystalline insulator tin telluride is known to host superconductivity when doped with indium (Sn1−xInxTe), and for low indium content (x = 0.04) it is known that the topological surface states are preserved. Here we present the growth, characterization and angle resolved photoemission spectroscopy analysis of samples with much heavier In doping (up to x ≈ 0.4), a regime where the superconducting temperature is increased nearly fourfold. We demonstrate that despite strong p-type doping, Dirac-like surface states persist.
The connection between the Fermi surface and charge-density-wave (CDW) order is revisited in 2H-TaSe 2 . Using angle-resolved photoemission spectroscopy, ab initio band-structure calculations, and an accurate tightbinding model, we develop the empirical k-resolved susceptibility function, which we use to highlight states that contribute to the susceptibility for a particular q vector. We show that although the Fermi surface is involved in the peaks in the susceptibility associated with CDW order, it is not through conventional Fermi surface nesting, but rather through finite energy transitions from states located far from the Fermi level. Comparison with monolayer TaSe 2 illustrates the different mechanisms that are involved in the absence of bilayer splitting.
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