Microwave Gaseous Discharges

Contains reports on three research projects.Atomic Energy Commission under Contract AT(30-1)- 184

Embedded Ribbons of Graphene Allotropes: An Extended Defect Perspective

Four fundamental dimer manipulations can be used to produce a variety of localized and extended defect structures in graphene. Two-dimensional templates result in graphene allotropes, here viewed as extended defects, which can exhibit either metallic or semiconducting electrical character. \emph{Embedded allotropic ribbons}--i.e. thin swaths of the new allotropes--can also be created within graphene. We examine these ribbons and find that they maintain the electrical character of their parent allotrope even when only a few atoms in width. Such extended defects may facilitate the construction of monolithic electronic circuitry.Comment: 24 pages, 21 figure

Plasma Physics

Contains reports on six research projects.United States Atomic Energy Commission (Contract AT(30-1)-1842

Microwave Gaseous Discharges

Contains reports on two research projects

Plasma Physics

Contains research objectives and reports on four research projects.U.S. Atomic Energy Commission (Contract AT(30-1)-1842)U.S. Atomic Energy Commission Contract W-7405-Eng-3

Reactive Multiphase Behavior of Co{sub 2} in Saline Aquifers Beneath the Colorado Plateau

Soil gas surveys have been carried out on the Colorado Plateau over areas with natural occurrences of CO{sub 2}. At Farnham Dome, Utah, and Springerville-St. Johns, Arizona, proven CO{sub 2} reservoirs occur at 600-800 m depth, but no anomalous soil gas CO{sub 2} flux was detected. Background CO{sub 2} fluxes of up to about 5 g m{sup -2} day{sup -1} were common in arid, poorly vegetated areas, and fluxes up to about 20 g m{sup -2} day{sup -1} were found at Springerville-St. Johns in heavily vegetated, wet ground adjacent to springs. These elevated fluxes are attributed to shallow root zone activity rather than to a deep upflow of CO{sub 2}. Localized areas of anomalously high CO{sub 2} gas flux ({approx} 100 g m{sup -2} day{sup -1}) were documented along the Little Grand Wash Fault Zone near Crystal Geyser, Utah and nearby in Ten Mile Graben, but those in Ten Mile Graben are not directly associated with the major faults. In both areas, features with a visible gas flux are present. Isotopic measurements on the CO{sub 2} gas confirm that it originated at depth. Evidence of widespread vein calcite at the surface at Farnham Dome and travertine deposits in the other areas suggests that there has been an outflow of CO{sub 2}-rich fluids in the past. 14C ages of pollen trapped in the travertine at Springerville-St. Johns record a period of CO{sub 2} leakage to the atmosphere between 887 {+-} 35 and 3219 {+-} 30 years BP. No travertine deposits appear to be currently forming. At Springerville-St. Johns, Crystal Geyser and Ten Mile Graben, there are significant outflows of high-bicarbonate water. Movement of CO{sub 2}-rich groundwaters may be the dominant mechanism controlling the mobility of CO{sub 2} today. The very localized nature of the soil gas anomalies, evidence of large scale discharge of CO{sub 2} over a very short period of time and the outflow of ground water containing dissolved CO{sub 2} will present challenges for effective, long term monitoring of CO{sub 2} leakage

Microwave Gaseous Discharges

Contains reports on two research projects

Epigenetic Chromatin Silencing: Bistability and Front Propagation

The role of post-translational modification of histones in eukaryotic gene regulation is well recognized. Epigenetic silencing of genes via heritable chromatin modifications plays a major role in cell fate specification in higher organisms. We formulate a coarse-grained model of chromatin silencing in yeast and study the conditions under which the system becomes bistable, allowing for different epigenetic states. We also study the dynamics of the boundary between the two locally stable states of chromatin: silenced and unsilenced. The model could be of use in guiding the discussion on chromatin silencing in general. In the context of silencing in budding yeast, it helps us understand the phenotype of various mutants, some of which may be non-trivial to see without the help of a mathematical model. One such example is a mutation that reduces the rate of background acetylation of particular histone side-chains that competes with the deacetylation by Sir2p. The resulting negative feedback due to a Sir protein depletion effect gives rise to interesting counter-intuitive consequences. Our mathematical analysis brings forth the different dynamical behaviors possible within the same molecular model and guides the formulation of more refined hypotheses that could be addressed experimentally.Comment: 19 pages, 5 figure