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Articles 1 - 19 of 19
Full-Text Articles in Physical Sciences and Mathematics
The Amazon Frontier Of Land-Use Change: Croplands And Consequences For Greenhouse Gas Emissions, Gillian L. Galford, Jerry Melillo, John F. Mustard, Carlos E.P. Cerri, Carlos C. Cerri
The Amazon Frontier Of Land-Use Change: Croplands And Consequences For Greenhouse Gas Emissions, Gillian L. Galford, Jerry Melillo, John F. Mustard, Carlos E.P. Cerri, Carlos C. Cerri
Rubenstein School of Environment and Natural Resources Faculty Publications
The Brazilian Amazon is one of the most rapidly developing agricultural frontiers in the world. The authors assess changes in cropland area and the intensification of cropping in the Brazilian agricultural frontier state of Mato Grosso using remote sensing and develop a greenhouse gas emissions budget. The most common type of intensification in this region is a shift from single-to double-cropping patterns and associated changes in management, including increased fertilization. Using the enhanced vegetation index (EVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, the authors created a green-leaf phenology for 2001-06 that was temporally smoothed with a wavelet filter. …
Identifying Controls On Surface Carbon Dioxide Efflux In A Semi-Arid Ecosystem, Katrina Elsie Ladd
Identifying Controls On Surface Carbon Dioxide Efflux In A Semi-Arid Ecosystem, Katrina Elsie Ladd
Boise State University Theses and Dissertations
This study focused on soil respiration, the least constrained process in the terrestrial carbon cycle, and a source of uncertainty for model predicted ecosystem response to climate change. Respiration processes that make up soil respiration respond to environmental influencing factors, temperature, and moisture. Respiration responses vary by site, time of year, and also year to year, confounding determination of individual influence of the factors, making soil respiration difficult to model. This research took advantage of the climate characteristics of a semi-arid system, in order to observe soil temperature and moisture influence on soil respiration. Field measurements of soil surface CO …
Carbon Dynamics In A Phragmites Australis Invaded Riparian Wetland, Steven Walters
Carbon Dynamics In A Phragmites Australis Invaded Riparian Wetland, Steven Walters
School of Natural Resources: Dissertations, Theses, and Student Research
Invasive plant species are widely recognized as a major threat to biodiversity and ecosystem stability. Wetland ecosystems tend to be much more susceptible to invasions because of their location on the landscape where water, nutrients, and the impacts of disturbances accumulate. Invasive plants have the ability to alter ecosystem processes and community/population dynamics. The ability of invasive plants to alter these processes can have profound economic consequences. In the United States, control of invasive wetland species alone costs approximately 155 million dollars annually. The state of Nebraska spends 2 million dollars annually controlling invasive plant species in the Platte River …
The Carbon Budget Of California, Christopher Potter
The Carbon Budget Of California, Christopher Potter
United States National Aeronautics and Space Administration: Publications
The carbon budget of a region can be defined as the sum of annual fluxes of carbon dioxide (CO2) and methane (CH4) greenhouse gases (GHGs) into and out of the regional surface coverage area. According to the state government’s recent inventory, California’s carbon budget is presently dominated by 115 MMTCE per year in fossil fuel emissions of CO2 (>85% of total annual GHG emissions) to meet energy and transportation requirements. Other notable (non-ecosystem) sources of carbon GHG emissions in 2004 were from cement- and lime-making industries (7%), livestock-based agriculture (5%), and waste treatment activities (2%). …
Electronic Properties Of Carbon Nanotubes With Distinct Bond Lengths, J E. Bunder, James M. Hill
Electronic Properties Of Carbon Nanotubes With Distinct Bond Lengths, J E. Bunder, James M. Hill
Faculty of Informatics - Papers (Archive)
In band structure calculations commonly used to derive the electronic properties of carbon nanotubes it is generally assumed that all bond lengths are equal. However, hexagonal carbon lattices are often irregular and may contain as many as three distinct bond lengths. A regular $(n,m)$ carbon nanotube will be metallic if p=(n-m)/3 for integer p. Here we analytically derive the generalized condition for metallic irregular carbon nanotubes. This condition is particularly relevant to small radius nanotubes and nanotubes experiencing small applied strains.
Strong Competition Between The Delta L And Delta T-C Flux Pinning Mechanisms In Mgb2 Doped With Carbon Containing Compounds, Shaban R. Ghorbani, Xiaolin Wang, Md S. Hossain, Qiwen Yao, S X. Dou, Sung-Ik Lee, K C. Chung, Y K. Kim
Strong Competition Between The Delta L And Delta T-C Flux Pinning Mechanisms In Mgb2 Doped With Carbon Containing Compounds, Shaban R. Ghorbani, Xiaolin Wang, Md S. Hossain, Qiwen Yao, S X. Dou, Sung-Ik Lee, K C. Chung, Y K. Kim
Australian Institute for Innovative Materials - Papers
The transport and magnetic properties of 10 wt % malic acid and 5 wt % nanocarbon doped MgB2 have been studied by measuring the resistivity (p), critical current density (jc), connectivity factor (AF), irreversibility field (Hirr), and upper critical field (Hc2). The pinning mechanisms are studied in terms of the collective pinning model. It was found that both mean free path (δl) and critical temperature (δTc) pinning mechanisms coexist in both doped MgB2. For both the malic acid and nanocarbon …
Extrusion Printing Conducting Gel-Carbon Nanotube Structures Upon Flexible Substrates, Geoffrey Pidcock, Marc In Het Panhuis
Extrusion Printing Conducting Gel-Carbon Nanotube Structures Upon Flexible Substrates, Geoffrey Pidcock, Marc In Het Panhuis
Faculty of Science - Papers (Archive)
Extrusion printing was investigatedas a wet-processing method forfabrication of robust, flexible conductingstructures. Layer resistance values of 7 -8 kO/cm were obtained for one printedlayer on flexible substrates. Increasingthe number of extrusion printed layer significantlyimproved resistance.
Diffusion Of Vitamin B12 In Gellan Gum-Carbon Nanotube Hydrogels, Cameron Ferris, Marc In Het Panhuis
Diffusion Of Vitamin B12 In Gellan Gum-Carbon Nanotube Hydrogels, Cameron Ferris, Marc In Het Panhuis
Faculty of Science - Papers (Archive)
We report on the diffusion of vitamin B12 through gellan gum-carbon nanotube hydrogels. The addition of carbon nanotubes to gellan gum reduced the vitamin B12 diffusion coefficient from 1.70 x 10-6 cm2/s to 0.70 x 10-6 cm2/s.
Source Attribution And Interannual Variability Of Arctic Pollution In Spring Constrained By Aircraft (Arctas, Arcpac) And Satellite (Airs) Observations Of Carbon Monoxide, J A. Fisher, D J. Jacob, M T. Purdy, M Kopacz, P Le Sager, C C. Carouge, C D. Holmes, R M. Yantosca, R L. Batchelor, K Strong, G S. Diskin, H E. Fuelberg, J S. Holloway, E J. Hyer, W. W Mcmillan, J Warner, D G. Streets, Q Zhang, Y Yang, S Wu
Source Attribution And Interannual Variability Of Arctic Pollution In Spring Constrained By Aircraft (Arctas, Arcpac) And Satellite (Airs) Observations Of Carbon Monoxide, J A. Fisher, D J. Jacob, M T. Purdy, M Kopacz, P Le Sager, C C. Carouge, C D. Holmes, R M. Yantosca, R L. Batchelor, K Strong, G S. Diskin, H E. Fuelberg, J S. Holloway, E J. Hyer, W. W Mcmillan, J Warner, D G. Streets, Q Zhang, Y Yang, S Wu
Faculty of Science - Papers (Archive)
We use aircraft observations of carbon monoxide (CO) from the NASA ARCTAS and NOAA ARCPAC campaigns in April 2008 together with multiyear (2003– 2008) CO satellite data from the AIRS instrument and a global chemical transport model (GEOS-Chem) to better understand the sources, transport, and interannual variability of pollution in the Arctic in spring. Model simulation of the aircraft data gives best estimates of CO emissions in April 2008 of 26 Tg month−1 for Asian anthropogenic, 9.4 for European anthropogenic, 4.1 for North American anthropogenic, 15 for Russian biomass burning (anomalously large that year), and 23 for Southeast Asian biomass …
Carbon Nanotube Architectures As Catalyst Supports For Proton Exchange Membrane Fuel Cells, Weimin Zhang, Peter Sherrell, Andrew I. Minett, Joselito M. Razal, Jun Chen
Carbon Nanotube Architectures As Catalyst Supports For Proton Exchange Membrane Fuel Cells, Weimin Zhang, Peter Sherrell, Andrew I. Minett, Joselito M. Razal, Jun Chen
Faculty of Science - Papers (Archive)
Catalyst support materials exhibit great influence on the performance and durability of proton exchange membrane (PEM) fuel cells. This minireview article summarises recent developments into carbon nanotube-based support materials for PEM fuel cells, including the membrane electrode assembly (MEA). The advantages of using CNTs to promote catalyst performance and stability, a perspective on research directions and strategies to improve fuel cell performance and durability are discussed. It is hoped that this mini-review will act as a conduit for future developments in catalyst supports and MEA design for PEM fuel cells.
Nanostructured Carbon Electrodes, Gordon G. Wallace, Jun Chen, Dan Li, Simon E. Moulton, Joselito M. Razal
Nanostructured Carbon Electrodes, Gordon G. Wallace, Jun Chen, Dan Li, Simon E. Moulton, Joselito M. Razal
Faculty of Science - Papers (Archive)
In its conducting form, carbon has proven to be a versatile, robust and high performing electrode material in areas such as energy conversion, energy storage and even medical bionics. In our laboratories we have been interested in the fabrication and utilization of nanostructured electrodes based on more recently discovered forms of carbon. These include carbon nanotubes and graphene.
Gel-Carbon Nanotube Materials: The Relationship Between Nanotube Network Connectivity And Conductivity, Naratip Songmee, Pisith Singjai, Marc In Het Panhuis
Gel-Carbon Nanotube Materials: The Relationship Between Nanotube Network Connectivity And Conductivity, Naratip Songmee, Pisith Singjai, Marc In Het Panhuis
Faculty of Science - Papers (Archive)
The electrical resistance of carbon nanotube networks (NNs) prepared from combinations of gellan gum, xanthan gum, Triton X-100, SWNT and MWNT is reported. It is demonstrated that the NN conductivity can be obtained by analysing the resistance of two overlapping NN as a function of their overlap distance. Unexpectedly, the connectivity between two overlapping NN was found to scale with the electrical conductivity over 4 orders of magnitude. Insights into the dependence of inter-NN contact on applied pressure were obtained.
Inkjet Printed Conducting Gel-Carbon Nanotube Materials, A Aldalbahi, Marc In Het Panhuis
Inkjet Printed Conducting Gel-Carbon Nanotube Materials, A Aldalbahi, Marc In Het Panhuis
Faculty of Science - Papers (Archive)
The inkjet printing of CNTbiopolymer composite inks onto solid and gel substrates was investigated. Changing the substrate from glass to gel resulted in an increase in the resistance of printed materials from 9.85 kΩ/cm to 39.42 kΩ/cm.
Preliminary Validation Of Column-Averaged Volume Mixing Ratios Of Carbon Dioxide And Methane Retrieved From Gosat Short-Wavelength Infrared Spectra, I Morino, O Uchino, M Inoue, Y Yoshida, T Yokota, P Wennberg, G C Toon, Debra Wunch, C M. Roehl, J Notholt, T Warneke, Janina Messerschmidt, David W. Griffith, Nicholas M. Deutscher, V Sherlock, B Connor, J Robinson, R Sussmann, M Rettinger
Preliminary Validation Of Column-Averaged Volume Mixing Ratios Of Carbon Dioxide And Methane Retrieved From Gosat Short-Wavelength Infrared Spectra, I Morino, O Uchino, M Inoue, Y Yoshida, T Yokota, P Wennberg, G C Toon, Debra Wunch, C M. Roehl, J Notholt, T Warneke, Janina Messerschmidt, David W. Griffith, Nicholas M. Deutscher, V Sherlock, B Connor, J Robinson, R Sussmann, M Rettinger
Faculty of Science - Papers (Archive)
Column-averaged volume mixing ratios of carbon dioxide and methane retrieved from the Greenhouse gases Observing SATellite (GOSAT) Short-Wavelength InfraRed observation (GOSAT SWIR XCO2 and XCH4) were compared with the reference data ob- 5 tained by ground-based high-resolution Fourier Transform Spectrometers (g-b FTSs) participating in the Total Carbon Column Observing Network (TCCON). Through calibrations of g-b FTSs with airborne in-situ measurements, the uncertainty of XCO2 and XCH4 associated with the g-b FTS was determined to be 0.8 ppm (0.2%) and 4 ppb (0.2%), respectively. The GOSAT products are validated with 10 these calibrated g-b FTS data. Preliminary results are as follows: …
Calibration Of The Total Carbon Column Observing Network Using Aircraft Profile Data, Debra Wunch, G C Toon, Paul O. Wennberg, Steven C. Wofsy, Robert S. Stephens, M K.R. Fischer, O Uchino, J Abshire, P Bernath, S C Biraud, J-F Blavier, C Boone, K P. Bowman, E V. Browell, T Campos, B Connor, Bruce C. Daube, Nicholas M. Deutscher, M Diao, J W. Elkins, Christoph Gerbig, E Gottlieb, David W. Griffith, D F. Hurst, Rodrigo Jimenez, Gretchen Keppel-Aleks, E A. Kort, Ronald Macatangay, T Machidda, H Matsueda, F Moore, I Morino, S Park, J Robinson, C M. Roehl, Y Sawa, V Sherlock, C Sweeney, T Tanaka, M A. Zondlo
Calibration Of The Total Carbon Column Observing Network Using Aircraft Profile Data, Debra Wunch, G C Toon, Paul O. Wennberg, Steven C. Wofsy, Robert S. Stephens, M K.R. Fischer, O Uchino, J Abshire, P Bernath, S C Biraud, J-F Blavier, C Boone, K P. Bowman, E V. Browell, T Campos, B Connor, Bruce C. Daube, Nicholas M. Deutscher, M Diao, J W. Elkins, Christoph Gerbig, E Gottlieb, David W. Griffith, D F. Hurst, Rodrigo Jimenez, Gretchen Keppel-Aleks, E A. Kort, Ronald Macatangay, T Machidda, H Matsueda, F Moore, I Morino, S Park, J Robinson, C M. Roehl, Y Sawa, V Sherlock, C Sweeney, T Tanaka, M A. Zondlo
Faculty of Science - Papers (Archive)
The Total Carbon Column Observing Network (TCCON) produces precise measurements of the column average dry-air mole fractions of CO2, CO, CH4, N2O and H2O at a variety of sites worldwide. These observations rely on spectroscopic parameters that are not known with sufficient accuracy to compute total columns that can be used in combination with in situ measurements. The TCCON must therefore be calibrated to World Meteorological Orga-nization (WMO) in situ trace gas measurement scales. We present a calibration of TCCON data using WMO-scale instrumentation aboard aircraft that measured profiles over four TCCON stations during 2008 and 2009. These calibrations are …
Linking Measured Carbon Dioxide Exchange By Sugarcane Crops And Biomass Production, O T Denmead, B.C.T. Macdonald, I. White, David W. Griffith, G Bryant, Travis A. Naylor, Stephen R. Wilson, W J. Wang
Linking Measured Carbon Dioxide Exchange By Sugarcane Crops And Biomass Production, O T Denmead, B.C.T. Macdonald, I. White, David W. Griffith, G Bryant, Travis A. Naylor, Stephen R. Wilson, W J. Wang
Faculty of Science - Papers (Archive)
CARBON TRADING and the growing interest in biofuel production from sugarcane necessitate the ability to measure gains and losses of soil organic C which may occur as a result. Modelling and soil sampling suggest that changes in soil C are likely to be < 1 t C/ha/y. Published accounts indicate that confirming such small changes by traditional soil sampling is error-prone and requires investigations of > 10 years. The paper explores the possibility of calculating soil gains or losses by subtracting the carbon stored in the crop biomass from the carbon gained by the crop through the uptake of carbon dioxide supplied by the atmosphere and processes in the soil. Although uptake and storage very nearly balanced each other in one–year measurements in …
Physical And Microbial Responses Of Dredged Sediment To Two-Soil-Stabilizing Amendments, Xanthan Gum And Guar Gum, For Use In Coastal Wetland Restoration, Lauren Land
LSU Master's Theses
In wetland sediments, organic matter provides a substrate for microbial activity. During metabolism, microbes release extracellular polymeric substances, which accumulate to bind soil particles. A similar concept can be implemented on a large scale to reduce wetland loss in Louisiana. Hypothetically, hydraulically dredged sediment can be amended with polymer and deposited on subsiding marshes as a restoration method where the polymer increases sediment stabilization until plants become established. This lab study focused on investigating the influence of natural polymer additions on particle aggregation to increase sediment stability and the effects on microbial activity. Sediments from three sites (i.e. freshwater, intermediate, …
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
Browse all Theses and Dissertations
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
Browse all Theses and Dissertations
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 …