High-Quality Magnetotransport in Graphene Using the Edge-Free Corbino Geometry.

We report fabrication of graphene devices in a Corbino geometry consisting of concentric circular electrodes with no physical edge connecting the inner and outer electrodes. High device mobility is realized using boron nitride encapsulation together with a dual-graphite gate structure. Bulk conductance measurement in the quantum Hall effect (QHE) regime outperforms previously reported Hall bar measurements, with improved resolution observed for both the integer and fractional QHE states. We identify apparent phase transitions in the fractional sequence in both the lowest and first excited Landau levels (LLs) and observe features consistent with electron solid phases in higher LLs.

Low levels of mercury inhibit the respiratory burst in human polymorphonuclear leukocytes.

The objective of this investigation was to examine the effects of low levels of Hg(II) on the respiratory burst of PMNs by monitoring O2 consumption, superoxide radical formation, and chemiluminescence. Hg(II) at concentrations of 10-100 ng/ml profoundly inhibited zymosan-stimulated human cells. This inhibition was immediate in onset and occurred with minimal loss of cell viability. Effects of Hg(II) on the PMN respiratory burst were compared with those of Sn, Pb, Se, Au, Ag and Cu. Only in the case of Ag and Cu did the inhibitory effects approach those of Hg. The results indicate that Hg(II) may serve as a specific inhibitor of components of the respiratory burst.