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Full-Text Articles in Physical Sciences and Mathematics
The Biogeochemistry Of Carbon Isotopes In Local Lakes, Stephen Edward Sadurski
The Biogeochemistry Of Carbon Isotopes In Local Lakes, Stephen Edward Sadurski
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Photosynthesis, respiration, and decay of organic matter all involve the transfer of carbon among the carbon-bearing species in the systems. These biogeochemical processes also fractionate the carbon isotope composition, which results in changes to the carbon isotope composition of the dissolved inorganic carbon (DIC) pool. This thesis presents two separate, but related studies regarding the influence of biogeochemical processes on carbon isotopes in local lakes. Crystal Lake is a small but deep glacial lake (12.5 acres, 11.9 meters). The study shows that during thermal stratification, the heaviest carbon can be found in the epilimnion near the surface, where photosynthesis dominates …
Temperature And Frequency Dependent Conduction Mechanisms Within Bulk Carbon Nanotube Materials, John Simmons Bulmer
Temperature And Frequency Dependent Conduction Mechanisms Within Bulk Carbon Nanotube Materials, John Simmons Bulmer
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The resistance of three types of bulk carbon nanotube (CNT) materials (floating catalyst CNT yarn, forest grown CNT yarn, and super acid spun CNT fiber) was measured from room temperature to 900 C. Fitting the curves to established conduction equations for disordered materials, competing conduction mechanisms pertaining to the material could be determined. Floating catalyst CNT yarn displayed both semiconductive and metallic isotropic behavior with a resistance minimum, similar to the behavior of crystalline graphite. It was found that, at room temperature, the semiconducting contribution-most likely junctions between CNTs-accounted for 99.99% of the overall resistance. The resistance of forest grown …
Ostwald Ripening Of Iron (Fe) Catalyst Nanoparticles On Aluminum Oxide Surfaces (Al2O3) For The Growth Of Carbon Nanotubes, Roberto I. Acosta
Ostwald Ripening Of Iron (Fe) Catalyst Nanoparticles On Aluminum Oxide Surfaces (Al2O3) For The Growth Of Carbon Nanotubes, Roberto I. Acosta
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Theoretical models have proposed that the nucleation and growth mechanism of carbon nanotubes (CNTs) has been affected by the catalytic activity of transition metals. The catalyst behavior during growth has been mainly associated as the responsible mechanism for the termination of CNT growth. Although several hypotheses have been developed to explain this mechanism, is still today an unresolved phenomenon. It was recently shown that the Ostwald ripening of iron (Fe) nanoparticles played a dominant role in the termination of CNT growth. The Ostwald ripening mechanism was further investigated as a function of thermal annealing in Hydrogen (H2) for …
The Impact Of Nutrient Availability And Algal Community On Carbon Isotope Fractionaion In Crystal Lake, Clark County, Ohio, April R. Wisebaker
The Impact Of Nutrient Availability And Algal Community On Carbon Isotope Fractionaion In Crystal Lake, Clark County, Ohio, April R. Wisebaker
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Crystal Lakes are a group of four interconnected lakes, located in southwestern Clark County, Ohio. Several studies have looked at separate geochemical and isotopic information at this location. However, no one has thoroughly studied the relationship between the algal community, geochemistry, and carbon isotope fractionation within Crystal Lake. The fractionation of carbon isotopes of dissolved inorganic carbonate is greatly affected by the process of photosynthesis; the amount of photosynthesis is affected by the amount of algae in the aquatic community; the amount of algae is affected by the available nutrients in system. Therefore, there should be a correlation between the …