A Possible Regenerative, Molten-Salt, Thermoelectric Fuel Cell

Molten or fused salts have been evaluated as possible thermoelectric materials because of the relatively good values of their figures of merit, their chemical stability, their long liquid range, and their ability to operate in conjunction with a nuclear reactor to produce heat. In general, molten salts are electrolytic conductors; therefore, there will be a transport of materials and subsequent decomposition with the passage of an electric current. It is possible nonetheless to overcome this disadvantage by using the decomposition products of the molten-salt electrolyte in a fuel cell. The combination of a thermoelectric converter and a fuel cell would lead to a regenerative system that may be useful

Paleoenvironmental Analysis and Test of Stratigraphic Cyclicity in the Nolichucky Shale and Maynardville Limestone (Upper Cambrian) in Central East Tennessee

The Upper Cambrian Nolichucky Shale and Maynardville Limestone (upper Conasauga Group) crop out along a succession of southeastward dipping imbricate thrust sheets, which trend northeast-southwest in the Valley and Ridge of eastern Tennessee. In the vicinity of Oak Ridge and Knoxville, Nolichucky and Maynardville outcrop and drill core have been examined at six localities. The Nolichucky contains an abundance of thick shale and thinly bedded shale and limestone, whereas the Maynardville is composed of very thick-bedded carbonate, predominantly limestone. In central east Tennessee fourteen major lithofacies are identified in the upper Conasauga Group. The Nolichucky/Maynardville sequence is subdivided into three parts representing: (1) a slightly deeper intracratonic basin (30-50 m water depth; lower Nolichucky, (2) a shallow intracratonic basin (5-30 m deep; upper Nolichucky), and (3) a peritidal platform (0-5 m deep; Maynardville). The Nolichucky Shale was deposited in a storm-dominated paleo­environmental setting, whereas the Maynardville Limestone is similar to other ancient tidally-influenced deposits. In the Nolichucky, the majority of carbonate production occurred in and around shoals and within cyanobacterial mats. Storms were effective in moving carbonate sediment off the shoals and mats into adjacent shale-dominated subtidal areas. The Maynardville represents small tidal flats that accreted vertically and migrated laterally. Sediment was produced in open-water subtidal areas, which were adjacent to tidal flats, and tides, storms, and fairweather waves transported sediment to nearby low-relief intertidal banks and supratidal islands. The distribution of facies along the Nolichucky/Maynardville bathymetric profile was much more irregular (mosaic-like) than predicted by the depositional model of earlier workers. An integrated approach of overlying substitutability analysis, embedded Markov chain analysis, and modified autoassociation analysis to verify statistically the occurrence of cycles in stratigraphic sequences is applied to the upper Conasauga Group of central east Tennessee. Stratigraphic sections within the Nolichucky Shale and in the Maynardville Limestone show weakly developed cyclicity, which is probably a result of the storm- and tide-dominated paleoenvironmental setting. Local processes were more important in controlling lithologic repetition than were larger-scale processes (e.g., geoidal, tectonic, or glacioeustatic). Large-scale processes have been documented in modern and other ancient settings, but their record may be masked in many sequences by local events

Isoprenoids determine Th1/Th2 fate in pathogenic T cells, providing a mechanism of modulation of autoimmunity by atorvastatin.

3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase is a critical enzyme in the mevalonate pathway that regulates the biosynthesis of cholesterol as well as isoprenoids that mediate the membrane association of certain GTPases. Blockade of this enzyme by atorvastatin (AT) inhibits the destructive proinflammatory T helper cell (Th)1 response during experimental autoimmune encephalomyelitis and may be beneficial in the treatment of multiple sclerosis and other Th1-mediated autoimmune diseases. Here we present evidence linking specific isoprenoid intermediates of the mevalonate pathway to signaling pathways that regulate T cell autoimmunity. We demonstrate that the isoprenoid geranylgeranyl-pyrophosphate (GGPP) mediates proliferation, whereas both GGPP and its precursor, farnesyl-PP, regulate the Th1 differentiation of myelin-reactive T cells. Depletion of these isoprenoid intermediates in vivo via oral AT administration hindered these T cell responses by decreasing geranylgeranylated RhoA and farnesylated Ras at the plasma membrane. This was associated with reduced extracellular signal-regulated kinase (ERK) and p38 phosphorylation and DNA binding of their cotarget c-fos in response to T cell receptor activation. Inhibition of ERK and p38 mimicked the effects of AT and induced a Th2 cytokine shift. Thus, by connecting isoprenoid availability to regulation of Th1/Th2 fate, we have elucidated a mechanism by which AT may suppress Th1-mediated central nervous system autoimmune disease