Giant magnetoresistance switching in multilayer graphene grown on cobalt.

Magnetic multilayer devices, showing large magnetoresistance (MR) effects, have revolutionized magnetic sensing and data storage sectors over the last few decades. Two-dimensional van der Waals layered materials are relatively new entrants in this area, and these materials can give rise to large MR effects with diverse physical origins. Here we report observation of giant MR switching (∼10 orders of magnitude) in multilayered graphene grown on cobalt (Co) substrates, which persists even at room temperature. The origin of this effect is linked with weak interlayer coupling of the graphene stacks, which gives rise to an 'interlayer MR' effect. This effect is found to be robust against some degree of inhomogeneity in the graphene stack, making it an attractive platform for the emerging area of flexible magnetic sensorics.

Giant current-perpendicular-to-plane magnetoresistance in multilayer graphene as grown on nickel.

Strong magnetoresistance effects are often observed in ferromagnet-nonmagnet multilayers, which are exploited in state-of-the-art magnetic field sensing and data storage technologies. In this work we report a novel current-perpendicular-to-plane magnetoresistance effect in multilayer graphene as grown on a catalytic nickel surface by chemical vapor deposition. A negative magnetoresistance effect of ∼10(4)% has been observed, which persists even at room temperature. This effect is correlated with the shape of the 2D peak as well as with the occurrence of D peak in the Raman spectrum of the as-grown multilayer graphene. The observed magnetoresistance is extremely high as compared to other known materials systems for similar temperature and field range and can be qualitatively explained within the framework of "interlayer magnetoresistance" (ILMR).

Low levels of ionic mercury modulate protein tyrosine phosphorylation in lymphocytes.

The ability of ionic mercury to induce protein tyrosine phosphorylation in mouse spleen cells and in the mouse WEHI-231 B-cell lymphoma was investigated. We have confirmed previous studies which showed that exposure to high levels (several hundred microM) of mercury lead to very large increases in the level of protein tyrosine phosphorylation in these cell systems. However we have also demonstrated that low levels (in the order of 0.1 to 1.0 microM) of mercury also significantly upregulate protein tyrosine phosphorylation. Mercury induced protein tyrosine phosphorylation is inhibited by the mercury chelator penicillamine and by pretreating treating target cells with the sulfhydryl blocking reagent N-hydroxymaleimide. These results suggest that exposure to low levels of mercury could potentially interfere with lymphocyte signal transduction and so offer a possible explanation as to how mercury exposure could lead to immune cellular dysfunction. On a molecular level, the results suggest that the site(s) of action with respect to mercury dependent induction of protein tyrosine phosphorylation is likely a free disulfide group or groups located on the outer leaflet of the plasma membrane.