Proposed New Method for Separating Isotopes
RECENTLY1 a double mercury discharge vessel was used (Fig. 1), in which a large current running in the outer vessel irradiated the small current discharge in the inner vessel with 2537 Å resonance radiation. This irradiation caused the running voltage and electron temperature in the inner discharge to be reduced appreciably over the non-irradiated mode of operation. The explanation offered was that the neutral Hg atoms in the inner vessel absorbed the resonance radiation and entered the 63P1 state (see Fig. 2), and from this level the atom was ionized by electron impact. In addition the 63P0 and 63P2 metastable levels are populated from the 63P1 level by electron collisions and by cumulative absorption and radiative decay of higher levels. Because the radiation field is doing approximately half the ionization work, the electron temperature drops correspondingly.
Rejection triggers liver transplant tolerance: Involvement of mesenchyme‐mediated immune control mechanisms in mice
Liver tolerance was initially recognized by the spontaneous acceptance of liver allografts in many species. The underlying mechanisms are not completely understood. However, liver transplant (LT) tolerance absolutely requires interferon (IFN)‐γ, a rejection‐associated inflammatory cytokine. In this study, we investigated the rejection of liver allografts deficient in the IFN‐γ receptor and reveal that the liver graft is equipped with machineries capable of counterattacking the host immune response through a mesenchyme‐mediated immune control (MMIC) mechanism. MMIC is triggered by T effector (Tef) cell‐derived IFN‐γ that drives expression of B7‐H1 on graft mesenchymal cells leading to Tef cell apoptosis. We describe the negative feedback loop between graft mesenchymal and Tef cells that ultimately results in LT tolerance. Comparable elevations of T‐regulatory cells and myeloid‐derived suppressor cells were observed in both rejection and tolerance groups and were not dependent on IFN‐γ stimulation, suggesting a critical role of Tef cell elimination in tolerance induction. We identify potent MMIC activity in hepatic stellate cells and liver sinusoidal endothelial cells. MMIC is unlikely exclusive to the liver, given that spontaneous acceptance of kidney allografts has been reported, although less commonly, probably reflecting variance in MMIC activity. Conclusion: MMIC may represent an important homeostatic mechanism that supports peripheral tolerance and could be a target for the prevention and treatment of transplant rejection. This study highlights that the graft is an active participant in the equipoise between tolerance and rejection and warrants more attention in the search for tolerance biomarkers. (Hepatology 2015;62:915–931)
Ionization of Cu, Ag, and Au by Electron Impact
The relative ionization probabilities of copper, silver, and gold by electron impact have been studied near threshold. Nearly monoenergetic electrons, obtained by means of the retarding potential difference method, were employed. Narrow peaks were found superimposed on the ion yield that arises from transition to the ion ground state. It was possible to correlate these peaks with groups of energy levels, many of which are known to autoionize. The ionization probability curve for formation of doubly ionized gold was also obtained and found to be a sum of linear functions of the electron excess energy. The onset of each linear section indicated the presence of an excited state of Au III. Three energy levels were located at 2.26, 3.92, and 7.81 ev above the ground state.