Science.gov

Sample records for external carbon source

  1. Direct growth and patterning of multilayer graphene onto a targeted substrate without an external carbon source.

    PubMed

    Kang, Dongseok; Kim, Won-Jun; Lim, Jung Ah; Song, Yong-Won

    2012-07-25

    Using only a simple tube furnace, we demonstrate the synthesis of patterned graphene directly on a designed substrate without the need for an external carbon source. Carbon atoms are absorbed onto Ni evaporator sources as impurities, and incorporated into catalyst layers during the deposition. Heat treatment conditions were optimized so that the atoms diffused out along the grain boundaries to form nanocrystals at the catalyst-substrate interfaces. Graphene patterns were obtained under patterned catalysts, which restricted graphene formation to within patterned areas. The resultant multilayer graphene was characterized by Raman spectroscopy and transmission electron microscopy to verify the high crystallinity and two-dimensional nanomorphology. Finally, a metal-semiconductor diode with a catalyst-graphene contact structure were fabricated and characterized to assess the semiconducting properties of the graphene sheets with respect to the display of asymmetric current-voltage behavior.

  2. Modeling the Effect of External Carbon Source Addition under Different Electron Acceptor Conditions in Biological Nutrient Removal Activated Sludge Systems.

    PubMed

    Hu, Xiang; Wisniewski, Kamil; Czerwionka, Krzysztof; Zhou, Qi; Xie, Li; Makinia, Jacek

    2016-02-16

    The aim of this study was to expand the International Water Association Activated Sludge Model No. 2d (ASM2d) to predict the aerobic/anoxic behavior of polyphosphate accumulating organisms (PAOs) and "ordinary" heterotrophs in the presence of different external carbon sources and electron acceptors. The following new aspects were considered: (1) a new type of the readily biodegradable substrate, not available for the anaerobic activity of PAOs, (2) nitrite as an electron acceptor, and (3) acclimation of "ordinary" heterotrophs to the new external substrate via enzyme synthesis. The expanded model incorporated 30 new or modified process rate equations. The model was evaluated against data from several, especially designed laboratory experiments which focused on the combined effects of different types of external carbon sources (acetate, ethanol and fusel oil) and electron acceptors (dissolved oxygen, nitrate and nitrite) on the behavior of PAOs and "ordinary" heterotrophs. With the proposed expansions, it was possible to improve some deficiencies of the ASM2d in predicting the behavior of biological nutrient removal (BNR) systems with the addition of external carbon sources, including the effect of acclimation to the new carbon source.

  3. Ion source with external RF antenna

    DOEpatents

    Leung, Ka-Ngo; Ji, Qing; Wilde, Stephen

    2005-12-13

    A radio frequency (RF) driven plasma ion source has an external RF antenna, i.e. the RF antenna is positioned outside the plasma generating chamber rather than inside. The RF antenna is typically formed of a small diameter metal tube coated with an insulator. An external RF antenna assembly is used to mount the external RF antenna to the ion source. The RF antenna tubing is wound around the external RF antenna assembly to form a coil. The external RF antenna assembly is formed of a material, e.g. quartz, which is essentially transparent to the RF waves. The external RF antenna assembly is attached to and forms a part of the plasma source chamber so that the RF waves emitted by the RF antenna enter into the inside of the plasma chamber and ionize a gas contained therein. The plasma ion source is typically a multi-cusp ion source.

  4. Evaluation of the feasibility of alcohols serving as external carbon sources for biological phosphorus removal induced by the oxic/extended-idle regime.

    PubMed

    Wang, Dongbo; Zheng, Wei; Li, Xiaoming; Yang, Qi; Liao, Dexiang; Zeng, Guangming

    2013-03-01

    Recently, a novel operational regime (i.e., the oxic/extended-idle [OEI] regime) has been reported to successfully achieve enhanced biological phosphorus removal (EBPR) when employing glucose and volatile fatty acids as the sole substrate. In the OEI regime, polyphosphate accumulating organisms (PAOs) could get a selective advantage over other populations during the extended-idle period where polyphosphate released but polyhydroxyalkanoates and glycogen transformations were negligible/low, thus energy requirements for maintenance purposes in the period could be covered by polyphosphate release. This study further evaluated the feasibility of alcohols as external carbon sources for EBPR induced by the OEI regime, as the available substrate in the raw wastewater is often deficient. First, phosphorus removal in the OEI process was compared, respectively, with methanol and ethanol as the sole substrate. The results showed that the ethanol-reactor achieved 90.8 ± 2.3% of phosphorus removal, which was approximate twofold than the methanol-reactor. Further studies displayed that the cells in the ethanol-reactor contained more PAOs, and had higher activities of exopolyphosphatase and polyphosphate kinase than those in the methanol-reactor. Also, the aerobic transformations of polyhydroxyalkanoates and glycogen in the ethanol-reactor were, respectively, higher and lower than those in the methanol-reactor, which were consistent with the reactors performances. Then, the feasibility of using ethanol as external substrate to enhance EBPR in the OEI process was confirmed for a municipal wastewater. Finally, EBPR performance and metabolic transformation values between the OEI and the anaerobic/oxic (A/O) regimes with ethanol as the sole substrate were compared. The results showed that EBPR in the ethanol-OEI reactor was higher than that in the ethanol-A/O reactor. All the above results proved that ethanol was a favorable external substrate to the OEI regime for EBPR enhancement.

  5. Unimodular gravity with external sources

    SciTech Connect

    Álvarez, Enrique; Herrero-Valea, Mario E-mail: mario.herrero@estudiante.uam.es

    2013-01-01

    The only allowed source of the gravitational field in the unimodular theory, invariant under area-preserving (transverse) diffeomorphisms as well as Weyl transformations, is just the traceless piece of the energy-momentum tensor. This fact notwithstanding, the free energy produced by arbitrary sources (not only static ones) is identical to the one predicted by general relativity. This encompasses all weak field tests of gravitation.

  6. Negative ion source with external RF antenna

    DOEpatents

    Leung, Ka-Ngo; Hahto, Sami K.; Hahto, Sari T.

    2007-02-13

    A radio frequency (RF) driven plasma ion source has an external RF antenna, i.e. the RF antenna is positioned outside the plasma generating chamber rather than inside. The RF antenna is typically formed of a small diameter metal tube coated with an insulator. An external RF antenna assembly is used to mount the external RF antenna to the ion source. The RF antenna tubing is wound around the external RF antenna assembly to form a coil. The external RF antenna assembly is formed of a material, e.g. quartz, which is essentially transparent to the RF waves. The external RF antenna assembly is attached to and forms a part of the plasma source chamber so that the RF waves emitted by the RF antenna enter into the inside of the plasma chamber and ionize a gas contained therein. The plasma ion source is typically a multi-cusp ion source. A converter can be included in the ion source to produce negative ions.

  7. Achieving low effluent NO3-N and TN concentrations in low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio without using external carbon source

    NASA Astrophysics Data System (ADS)

    Cao, Jiashun; Oleyiblo, Oloche James; Xue, Zhaoxia; Otache, Y. Martins; Feng, Qian

    2015-07-01

    Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal (BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, anaerobic anoxic oxic (A2/O). The ASM2d implemented on the platform of WEST2011 software and the BioWin activated sludge/anaerobic digestion (AS/AD) models were used in this study with the aim of consistently achieving the designed effluent criteria at a low operational cost. Four ASM2d parameters (the reduction factor for denitrification , the maximum growth rate of heterotrophs (µH), the rate constant for stored polyphosphates in PAOs ( q pp), and the hydrolysis rate constant ( k h)) were adjusted. Whereas three BioWin parameters (aerobic decay rate ( b H), heterotrophic dissolved oxygen (DO) half saturation ( K OA), and Y P/acetic) were adjusted. Calibration of the two models was successful; both models have average relative deviations (ARD) less than 10% for all the output variables. Low effluent concentrations of nitrate nitrogen (N-NO3), total nitrogen (TN), and total phosphorus (TP) were achieved in a full-scale BNR treatment plant having low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio (COD/TKN). The effluent total nitrogen and nitrate nitrogen concentrations were improved by 50% and energy consumption was reduced by approximately 25%, which was accomplished by converting the two-pass aerobic compartment of the plug-flow bioreactor to anoxic reactors and being operated in an alternating mode. Findings in this work are helpful in improving the operation of wastewater treatment plant while eliminating the cost of external carbon source and reducing energy consumption.

  8. Facile synthesis of carbon doped TiO2 nanowires without an external carbon source and their opto-electronic properties.

    PubMed

    Kiran, Vankayala; Sampath, Srinivasan

    2013-11-07

    The present study demonstrates a simple protocol for the preparation of one dimensional (1D) oxidized titanium carbide nanowires and their opto-electronic properties. The oxidized titanium carbide nanowires (Ox-TiC-NW) are prepared from TiC nanowires (TiC-NW) that are in turn synthesized from micron sized TiC particles using the solvothermal technique. The Ox-TiC-NW is characterized by X-ray diffraction, UV-Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Raman spectroscopy. Thermal oxidation of TiC-NW yields carbon doped TiO2-NW (C-TiO2-NW), a simple methodology to obtain 1D C-TiO2-NW. Temperature dependent Raman spectra reveal characteristic bands for TiO2-NW. Electrical characterization of individual C-TiO2-NW is performed by fabricating a device structure using the focused ion beam deposition technique. The opto-electronic properties of individual C-TiO2-NW demonstrate visible light activity and the parameters obtained from photoconductivity measurements reveal very good sensitivity. This methodology opens up the possibility of using C-TiO2-NW in electronic and opto-electronic device applications.

  9. Facile synthesis of carbon doped TiO2 nanowires without an external carbon source and their opto-electronic properties

    NASA Astrophysics Data System (ADS)

    Kiran, Vankayala; Sampath, Srinivasan

    2013-10-01

    The present study demonstrates a simple protocol for the preparation of one dimensional (1D) oxidized titanium carbide nanowires and their opto-electronic properties. The oxidized titanium carbide nanowires (Ox-TiC-NW) are prepared from TiC nanowires (TiC-NW) that are in turn synthesized from micron sized TiC particles using the solvothermal technique. The Ox-TiC-NW is characterized by X-ray diffraction, UV-Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Raman spectroscopy. Thermal oxidation of TiC-NW yields carbon doped TiO2-NW (C-TiO2-NW), a simple methodology to obtain 1D C-TiO2-NW. Temperature dependent Raman spectra reveal characteristic bands for TiO2-NW. Electrical characterization of individual C-TiO2-NW is performed by fabricating a device structure using the focused ion beam deposition technique. The opto-electronic properties of individual C-TiO2-NW demonstrate visible light activity and the parameters obtained from photoconductivity measurements reveal very good sensitivity. This methodology opens up the possibility of using C-TiO2-NW in electronic and opto-electronic device applications.The present study demonstrates a simple protocol for the preparation of one dimensional (1D) oxidized titanium carbide nanowires and their opto-electronic properties. The oxidized titanium carbide nanowires (Ox-TiC-NW) are prepared from TiC nanowires (TiC-NW) that are in turn synthesized from micron sized TiC particles using the solvothermal technique. The Ox-TiC-NW is characterized by X-ray diffraction, UV-Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Raman spectroscopy. Thermal oxidation of TiC-NW yields carbon doped TiO2-NW (C-TiO2-NW), a simple methodology to obtain 1D C-TiO2-NW. Temperature dependent Raman spectra reveal characteristic bands for TiO2-NW. Electrical characterization of individual C-TiO2-NW is performed by fabricating a device structure using the

  10. Calculation of external dose from distributed source

    SciTech Connect

    Kocher, D.C.

    1986-01-01

    This paper discusses a relatively simple calculational method, called the point kernel method (Fo68), for estimating external dose from distributed sources that emit photon or electron radiations. The principles of the point kernel method are emphasized, rather than the presentation of extensive sets of calculations or tables of numerical results. A few calculations are presented for simple source geometries as illustrations of the method, and references and descriptions are provided for other caluclations in the literature. This paper also describes exposure situations for which the point kernel method is not appropriate and other, more complex, methods must be used, but these methods are not discussed in any detail.

  11. Query Modification through External Sources to Support Clinical Decisions

    DTIC Science & Technology

    2014-11-01

    Query Modification through External Sources to Support Clinical Decisions Raymond Wan1, Jannifer Hiu-Kwan Man2, and Ting-Fung Chan1 1School of Life...query modifications that use either external data sources or a domain expert. While each method gave slightly different results, we discovered that...biomedical literature offers many possible paths of investigation, our study focused on modifications to the query using external data sources. We submitted 5

  12. Influence of carbon sources on nutrient removal in A(2)/O-MBRs: Availability assessment of internal carbon source.

    PubMed

    Xu, Rongle; Fan, Yaobo; Wei, Yuansong; Wang, Yawei; Luo, Nan; Yang, Min; Yuan, Xing; Yu, Rong

    2016-10-01

    Both internal carbon source and some external carbon sources were used to improve the nutrient removal in Anaerobic-Anoxic-Oxic-Membrane Bioreactor (A(2)/O-MBRs), and their technical and cost analysis was investigated. The experimental results showed that the nutrient removals were improved by all the carbon source additions. The total nitrogen and phosphorus removal efficiency were higher in the experiments with external carbon source additions than that with internal carbon source addition. It was found that pathways of nitrogen and phosphorus transform were different dependent on different carbon source additions by the mass balance analysis. With external carbon source addition, the simultaneous nitrification and denitrification occurred in aerobic zone, and the P-uptake in aerobic phase was evident. Therefore, with addition of C-MHP (internal carbon source produced from sludge pretreatment by microwave-H2O2 process), the denitrification and phosphorus-uptake in anoxic zone was notable. Cost analysis showed that the unit nitrogen removal costs were 57.13CNY/kg N of C-acetate addition and 54.48CNY/kgN of C-MHP addition, respectively. The results indicated that the C-MHP has a good technical and economic feasibility to substitute external carbon sources partially for nutrient removal.

  13. Integrated Science Assessment for Carbon Monoxide (First External Review Draft)

    EPA Science Inventory

    EPA has announced that the First External Review Draft of the Integrated Science Assessment (ISA) for Carbon Monoxide (CO) and related Annexes have been made available for independent peer review and public review. This draft ISA document represents a concise synthesis and evalua...

  14. Integrated Science Assessment for Carbon Monoxide (Second External Review Draft)

    EPA Science Inventory

    EPA has announced that the Second External Review Draft of the Integrated Science Assessment (ISA) for Carbon Monoxide (CO) and related Annexes have been made available for independent peer review and public review. This draft ISA document represents a concise synthesis and evalu...

  15. Constraining the effective action by a method of external sources

    NASA Astrophysics Data System (ADS)

    Garbrecht, Björn; Millington, Peter

    2016-05-01

    We propose a novel method of evaluating the effective action, wherein the physical one- and two-point functions are obtained in the limit of non-vanishing external sources. We illustrate the self-consistency of this method by recovering the usual 2PI effective action due to Cornwall, Jackiw and Tomboulis, differing only by the fact that the saddle-point evaluation of the path integral is performed along the extremal quantum, rather than classical, path. As such, this approach is of particular relevance to situations where the dominant quantum and classical paths are non-perturbatively far away from one-another. A pertinent example is the decay of false vacua in radiatively-generated potentials, as may occur for the electroweak vacuum of the Standard Model. In addition, we describe how the external sources may instead be chosen so as to yield the two-particle-point-irreducible (2PPI) effective action of Coppens and Verschelde. Finally, in the spirit of the symmetry-improved effective action of Pilaftsis and Teresi, we give an example of how the external sources can be used to preserve global symmetries in truncations of the 2PI effective action. Specifically, in the context of an O (2) model with spontaneous symmetry breaking, we show that this approach allows the Hartree-Fock approximation to be re-organized, such that the Goldstone boson remains massless algebraically in the symmetry-broken phase and we obtain the correct second-order thermal phase transition.

  16. The Albuquerque carbon monoxide source apportionment study

    SciTech Connect

    Einfeld, W.

    1988-07-01

    At the request of the New Mexico Environmental Improvement Division, a study was carried out to examine, in detail, the relative contribution of various combustion sources to ambient carbon monoxide in Albuquerque during the winter season evening hours. The two-month field study (January--February 1985) included aerosol and gas monitoring at two sites in the Albuquerque area. Source contributions to ambient carbon monoxide were determined by regression techniques using tracer elements and by carbon isotope measurements on collected carbon monoxide. Results from isotopic carbon analysis of carbon monoxide show that, on average, mobile sources contributed 68 percent and wood burning sources 32 percent to ambient carbon monoxide levels during winter season evening hours. Good agreement was found between results from carbon isotope and linear regression techniques used to estimate average source strengths. The study results point to the significance of both mobile and residential wood burning sources as contributors to ambient carbon monoxide levels. 1 ref., 10 figs., 19 tabs.

  17. TEM Pump With External Heat Source And Sink

    NASA Technical Reports Server (NTRS)

    Nesmith, Bill J.

    1991-01-01

    Proposed thermoelectric/electromagnetic (TEM) pump driven by external source of heat and by two or more heat pipe radiator heat sink(s). Thermoelectrics generate electrical current to circulate liquid metal in secondary loop of two-fluid-loop system. Intended for use with space and terrestrial dual loop liquid metal nuclear reactors. Applications include spacecraft on long missions or terrestrial beacons or scientific instruments having to operate in remote areas for long times. Design modified to include multiple radiators, converters, and ducts, as dictated by particular application.

  18. Improvements to the internal and external antenna H(-) ion sources at the Spallation Neutron Source.

    PubMed

    Welton, R F; Dudnikov, V G; Han, B X; Murray, S N; Pennisi, T R; Pillar, C; Santana, M; Stockli, M P; Turvey, M W

    2014-02-01

    The Spallation Neutron Source (SNS), a large scale neutron production facility, routinely operates with 30-40 mA peak current in the linac. Recent measurements have shown that our RF-driven internal antenna, Cs-enhanced, multi-cusp ion sources injects ∼55 mA of H(-) beam current (∼1 ms, 60 Hz) at 65-kV into a Radio Frequency Quadrupole (RFQ) accelerator through a closely coupled electrostatic Low-Energy Beam Transport system. Over the last several years a decrease in RFQ transmission and issues with internal antennas has stimulated source development at the SNS both for the internal and external antenna ion sources. This report discusses progress in improving internal antenna reliability, H(-) yield improvements which resulted from modifications to the outlet aperture assembly (applicable to both internal and external antenna sources) and studies made of the long standing problem of beam persistence with the external antenna source. The current status of the external antenna ion source will also be presented.

  19. External Pressure Testing of the 60-Watt Isotopic Heat Source

    SciTech Connect

    Frazier, T. A.; Christenbury, S. T.

    1995-03-15

    The purpose of this manual is to establish the capability of the IHS generator system to contain its radioisotopic source under an accident scenario in which the generator is deposited in the ocean at great depth. This procedure is to be used on assemblies designated to demonstrate the capability of the 60-watt IHS in external pressure environments. A qualified helium leak technician (NDE) performs evaluations during post test activities. Quality Engineering (QE) is present during testing to monitor activities. Testing involves a 60-watt IHS/Heater Head Assembly with the simulant yttria in place of the isotopic fuel. The standard length 0.094 inch diameter SST dowel pin is replaced with a longer pin to facilitate disassembly. The assembly is tested to 1000 atmospheres (-15,000 psi). It is then evaluated. If it shows no evidence of collapse, an additional test is conducted for information only. The Source Document is "Safety Test Program Plan for the 60-Watt Isotopic Heat Source (IHS)", TBE-32156-IHS-008 Issue

  20. External Sources of Water for Mercury's Putative Ice Deposits

    NASA Technical Reports Server (NTRS)

    Moses, Julianne I.; Rawlins, Katherine; Zahnle, Kevin; Dones, Luke

    1999-01-01

    Radar images have revealed the possible presence of ice deposits in Mercury's polar regions. Although thermal models indicate that water ice can be stable in permanently shaded regions near Mercury's poles, the ultimate source of the water remains unclear. We use stochastic models and other theoretical methods to investigate the role of external sources in supplying Mercury with the requisite amount of water. By extrapolating the current terrestrial influx of interplanetary dust particles to that at Mercury, we find that continual micrometeoritic bombardment of Mercury over the last 3.5 byr could have resulted in the delivery of (3-60) x 10(exp 16) grams of water ice to the permanently shaded regions at Mercury's poles (equivalent to an average ice thickness of 0.8-20 m). Erosion by micrometeoritic impact on exposed ice deposits could reduce the above value by about a half. For comparison, the current ice deposits on Mercury are believed to be somewhere between approx. 2 and 20 m thick. Using a Monte Carlo model to simulate the impact history of Mercury, we find that asteroids and comets can also deliver an amount of water consistent with the observations. Impacts from Jupiter-family comets over the last 3.5 billion years can supply (0.1-200) x 10(exp 16) grams of water to Mercury's polar regions (corresponding to ice deposits 0.05-60 m thick), Halley-type comets can supply (0.2-20) x 10(exp 16) grams of water to the poles (0.07-7 m of ice), and asteroids can provide (0.4-20) x 10(exp 16) grams of water to the poles (0.1-8 m of ice). Although all these external sources are nominally sufficient to explain the estimated amount of ice currently at Mercury's poles, impacts by a few large comets and/or asteroids seem to provide the best explanation for both the amount and cleanliness of the ice deposits on Mercury. Despite their low population estimates in the inner solar system, Jupiter-family comets are particularly promising candidates for delivering water to Mercury

  1. Computer simulations for rf design of a Spallation Neutron Source external antenna H ion source

    SciTech Connect

    Lee, Sung-Woo; Goulding, Richard Howell; Kang, Yoon W; Shin, Ki; Welton, Robert F

    2010-01-01

    Electromagnetic modeling of the multicusp external antenna H ion source for the Spallation Neutron Source SNS has been performed in order to optimize high-power performance. During development of the SNS external antenna ion source, antenna failures due to high voltage and multicusp magnet holder rf heating concerns under stressful operating conditions led to rf characteristics analysis. In rf simulations, the plasma was modeled as an equivalent lossy metal by defining conductivity as . Insulation designs along with material selections such as ferrite and Teflon could be included in the computer simulations to compare antenna gap potentials, surface power dissipations, and input impedance at the operating frequencies, 2 and 13.56 MHz. Further modeling and design improvements are outlined in the conclusion.

  2. Computer simulations for rf design of a Spallation Neutron Source external antenna H- ion source.

    PubMed

    Lee, S W; Goulding, R H; Kang, Y W; Shin, K; Welton, R F

    2010-02-01

    Electromagnetic modeling of the multicusp external antenna H(-) ion source for the Spallation Neutron Source (SNS) has been performed in order to optimize high-power performance. During development of the SNS external antenna ion source, antenna failures due to high voltage and multicusp magnet holder rf heating concerns under stressful operating conditions led to rf characteristics analysis. In rf simulations, the plasma was modeled as an equivalent lossy metal by defining conductivity as sigma. Insulation designs along with material selections such as ferrite and Teflon could be included in the computer simulations to compare antenna gap potentials, surface power dissipations, and input impedance at the operating frequencies, 2 and 13.56 MHz. Further modeling and design improvements are outlined in the conclusion.

  3. Emittance studies of the Spallation Neutron Source external-antenna H- ion source.

    PubMed

    Han, B X; Stockli, M P; Welton, R F; Pennisi, T R; Murray, S N; Santana, M; Long, C D

    2010-02-01

    A new Allison-type emittance scanner has been built to characterize the ion sources and low energy beam transport systems at Spallation Neutron Source. In this work, the emittance characteristics of the H(-) beam produced with the external-antenna rf-driven ion source and transported through the two-lens electrostatic low energy beam transport are studied. The beam emittance dependence on beam intensity, extraction parameters, and the evolution of the emittance and twiss parameters over beam pulse duration are presented.

  4. Liquid metal ion source assembly for external ion injection into an electron string ion source (ESIS)

    NASA Astrophysics Data System (ADS)

    Segal, M. J.; Bark, R. A.; Thomae, R.; Donets, E. E.; Donets, E. D.; Boytsov, A.; Ponkin, D.; Ramsdorf, A.

    2016-02-01

    An assembly for a commercial Ga+ liquid metal ion source in combination with an ion transportation and focusing system, a pulse high-voltage quadrupole deflector, and a beam diagnostics system has been constructed in the framework of the iThemba LABS (Cape Town, South Africa)—JINR (Dubna, Russia) collaboration. First, results on Ga+ ion beam commissioning will be presented. Outlook of further experiments for measurements of charge breeding efficiency in the electron string ion source with the use of external injection of Ga+ and Au+ ion beams will be reported as well.

  5. Liquid metal ion source assembly for external ion injection into an electron string ion source (ESIS)

    SciTech Connect

    Segal, M. J.; Bark, R. A.; Thomae, R.; Donets, E. E.; Donets, E. D.; Boytsov, A.; Ponkin, D.; Ramsdorf, A.

    2016-02-15

    An assembly for a commercial Ga{sup +} liquid metal ion source in combination with an ion transportation and focusing system, a pulse high-voltage quadrupole deflector, and a beam diagnostics system has been constructed in the framework of the iThemba LABS (Cape Town, South Africa)—JINR (Dubna, Russia) collaboration. First, results on Ga{sup +} ion beam commissioning will be presented. Outlook of further experiments for measurements of charge breeding efficiency in the electron string ion source with the use of external injection of Ga{sup +} and Au{sup +} ion beams will be reported as well.

  6. Investigation of noise sources and propagation in external gear pumps

    NASA Astrophysics Data System (ADS)

    Opperwall, Timothy J.

    Oil hydraulics is widely accepted as the best technology for transmitting power in many engineering applications due to its advantages in power density, control, layout flexibility, and efficiency. Due to these advantages, hydraulic systems are present in many different applications including construction, agriculture, aerospace, automotive, forestry, medical, and manufacturing, just to identify a few. Many of these applications involve the systems in close proximity to human operators and passengers where noise is one of the main constraints to the acceptance and spread of this technology. As a key component in power transfer, displacement machines can be major sources of noise in hydraulic systems. Thus, investigation into the sources of noise and discovering strategies to reduce noise is a key part of applying fluid power systems to a wider range of applications, as well as improving the performance of current hydraulic systems. The present research aims to leverage previous efforts and develop new models and experimental techniques in the topic of noise generation caused by hydrostatic units. This requires challenging and surpassing current accepted methods in the understanding of noise in fluid power systems. This research seeks to expand on the previous experimental and modeling efforts by directly considering the effect that system and component design changes apply on the total sound power and the sound frequency components emitted from displacement machines and the attached lines. The case of external gear pumps is taken as reference for a new model to understand the generation and transmission of noise from the sources out to the environment. The lumped parameter model HYGESim (HYdraulic GEar machine Simulator) was expanded to investigate the dynamic forces on the solid bodies caused by the pump operation and to predict interactions with the attached system. Vibration and sound radiation were then predicted using a combined finite element and boundary

  7. Does External Knowledge Sourcing Enhance Market Performance? Evidence from the Korean Manufacturing Industry.

    PubMed

    Lee, Kibaek; Yoo, Jaeheung; Choi, Munkee; Zo, Hangjung; Ciganek, Andrew P

    2016-01-01

    Firms continuously search for external knowledge that can contribute to product innovation, which may ultimately increase market performance. The relationship between external knowledge sourcing and market performance is not well-documented. The extant literature primarily examines the causal relationship between external knowledge sources and product innovation performance or to identify factors which moderates the relationship between external knowledge sourcing and product innovation. Non-technological innovations, such as organization and marketing innovations, intervene in the process of external knowledge sourcing to product innovation to market performance but has not been extensively examined. This study addresses two research questions: does external knowledge sourcing lead to market performance and how does external knowledge sourcing interact with a firm's different innovation activities to enhance market performance. This study proposes a comprehensive model to capture the causal mechanism from external knowledge sourcing to market performance. The research model was tested using survey data from manufacturing firms in South Korea and the results demonstrate a strong statistical relationship in the path of external knowledge sourcing (EKS) to product innovation performance (PIP) to market performance (MP). Organizational innovation is an antecedent to EKS while marketing innovation is a consequence of EKS, which significantly influences PIP and MP. The results imply that any potential EKS effort should also consider organizational innovations which may ultimately enhance market performance. Theoretical and practical implications are discussed as well as concluding remarks.

  8. Does External Knowledge Sourcing Enhance Market Performance? Evidence from the Korean Manufacturing Industry

    PubMed Central

    Lee, Kibaek; Yoo, Jaeheung; Choi, Munkee; Zo, Hangjung; Ciganek, Andrew P.

    2016-01-01

    Firms continuously search for external knowledge that can contribute to product innovation, which may ultimately increase market performance. The relationship between external knowledge sourcing and market performance is not well-documented. The extant literature primarily examines the causal relationship between external knowledge sources and product innovation performance or to identify factors which moderates the relationship between external knowledge sourcing and product innovation. Non-technological innovations, such as organization and marketing innovations, intervene in the process of external knowledge sourcing to product innovation to market performance but has not been extensively examined. This study addresses two research questions: does external knowledge sourcing lead to market performance and how does external knowledge sourcing interact with a firm’s different innovation activities to enhance market performance. This study proposes a comprehensive model to capture the causal mechanism from external knowledge sourcing to market performance. The research model was tested using survey data from manufacturing firms in South Korea and the results demonstrate a strong statistical relationship in the path of external knowledge sourcing (EKS) to product innovation performance (PIP) to market performance (MP). Organizational innovation is an antecedent to EKS while marketing innovation is a consequence of EKS, which significantly influences PIP and MP. The results imply that any potential EKS effort should also consider organizational innovations which may ultimately enhance market performance. Theoretical and practical implications are discussed as well as concluding remarks. PMID:28006022

  9. A Fluorescent Source NDIR Carbon Monoxide Analyzer

    NASA Technical Reports Server (NTRS)

    Link, W. T.; McClatchie, E. A.; Watson, D. A.; Compher, A. B.

    1971-01-01

    This paper describes a new technique for measuring trace quantities of carbon monoxide by the nondispersive infrared (NDIR) methods. The technique uses the property of infrared fluorescence in a gas to generate a specific source of radiation which is an exact match of the absorption spectrum of the fundamental band of carbon monoxide. This results in an instrument with high sensitivity and specificity for CO. A novel method of referencing using an isotopic species of CO confers great stability on the instrument.

  10. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  11. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  12. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  13. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  14. 10 CFR 34.21 - Limits on external radiation levels from storage containers and source changers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Limits on external radiation levels from storage... INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Equipment § 34.21 Limits on external radiation levels from storage containers and source changers. The...

  15. A study of JET carbon impurity sources

    NASA Astrophysics Data System (ADS)

    Strachan, J. D.; Corrigan, G.; Stamp, M.; Spence, J.; Zacks, J.; JET-EFDA Contributors

    2009-06-01

    This paper compares experimental JET carbon and hydrogen visible emission to EDGE2D/NIMBUS calculations. The calculations themselves indicate that: (1) the integrated deuterium ionization in the SOL is proportional to the D α chordal integrated photon flux, (2) the carbon ionization in the SOL or the divertor is proportional to the calculated CIII chordal light, and (3) the ratio of line integrated photon fluxes from a vertical chord to a horizontal chord indicates whether the main chamber SOL content originated primarily from a wall source or from ion flow out of the divertor. Comparison was made to both inter-ELM H-Mode and L-Mode JET gas box divertor plasmas. The calculations infer that the experimental core contamination was caused by carbon sputtering arising primarily from the main chamber. The experimental, main chamber carbon yield was 1-4% in L-Mode and 5-10% in the inter-ELM H-Mode period.

  16. Geolocating Russian sources for Arctic black carbon

    NASA Astrophysics Data System (ADS)

    Cheng, Meng-Dawn

    2014-08-01

    To design and implement an effective emission control strategy for black carbon (BC), the locations and strength of BC sources must be identified. Lack of accurate source information from the Russian Federation has created difficulty for a range of research and policy activities in the Arctic because Russia occupies the largest landmass in the Arctic Circle. A project was initiated to resolve emission sources of BC in the Russian Federation by using the Potential Source Contribution Function (PSCF). It used atmospheric BC data from two Arctic sampling stations at Alert Nunavut, Canada, and Tiksi Bay, Russia. The geographical regions of BC emission sources in Russia were identified and summarized as follows: (1) a region surrounding Moscow, (2) regions in Eurasia stretching along the Ural Mountains from the White Sea to the Black Sea, and (3) a number of scattered areas from western Siberia to the Russian Far East. Particulate potassium ions, non-marine sulfate, and vanadium were used to assist in resolving the source types: forest fire/biomass burning, coal-fired power plant, and oil combustion. Correlating these maps with the BC map helped to resolve source regions of BC emissions and connect them to their corresponding source types. The results imply that a region south of Moscow and another north of the Ural Mountains could be significant BC sources, but none of the grid cells in these regions could be linked to forest fires, oil combustion, or coal-fired power plants based on these three markers.

  17. [Optimization of nitrate recirculation flow and external carbon dosage integrated control for A/O biological nitrogen removal process].

    PubMed

    Ma, Yong; Peng, Yong-Zhen; Sun, Hong-Wei

    2008-05-01

    In order to improve A/O process denitrification efficiency, five integrated control strategies of nitrate recirculation flow and external carbon dosage for denitrification were proposed and evaluated using the COST/IWA simulation Benchmark. Results show that control strategy No.1 is the best integrated control strategies from both external carbon consumption, effluent quality, and the stability of controller. It comprises two feedback control loops: one is to determine the flow rate of external carbon source, keeping the nitrate concentration at the end of anoxic zone at a pre-specified level 2 mg/L, and the other is to adjust the flow rates of the nitrate recirculation to keep the nitrate concentration at the end of the aerobic zone at a pre-specified level based on the effluent quality (usually 8-12 mg/L). This strategy can guarantee highly effective use of anoxic denitrification capacity in the low-load condition, and meet effluent discharge standards through carbon dosage in the high-load condition.

  18. IRIS Toxicological Review of Carbon Tetrachloride (External Review Draft)

    EPA Science Inventory

    EPA conducted a peer review of the scientific basis supporting the human health hazard and dose-response assessment of carbon tetrachloride that will appear on the Integrated Risk Information System (IRIS) database. Peer review is meant to ensure that science is used credibly and...

  19. AIR QUALITY CRITERIA CARBON MONOXIDE, EXTERNAL REVIEW DRAFT

    EPA Science Inventory

    The U.S. Environmental Protection Agency (EPA) promulgates the National Ambient Air Quality Standards (NAAQS) on the basis of scientific information contained in criteria documents. The last air quality criteria document for carbon monoxide (CO) was completed by EPA in 1991. This...

  20. Improvements to the internal and external antenna H{sup −} ion sources at the Spallation Neutron Source

    SciTech Connect

    Welton, R. F. Han, B. X.; Murray, S. N.; Pennisi, T. R.; Pillar, C.; Santana, M.; Stockli, M. P.; Dudnikov, V. G.; Turvey, M. W.

    2014-02-15

    The Spallation Neutron Source (SNS), a large scale neutron production facility, routinely operates with 30–40 mA peak current in the linac. Recent measurements have shown that our RF-driven internal antenna, Cs-enhanced, multi-cusp ion sources injects ∼55 mA of H{sup −} beam current (∼1 ms, 60 Hz) at 65-kV into a Radio Frequency Quadrupole (RFQ) accelerator through a closely coupled electrostatic Low-Energy Beam Transport system. Over the last several years a decrease in RFQ transmission and issues with internal antennas has stimulated source development at the SNS both for the internal and external antenna ion sources. This report discusses progress in improving internal antenna reliability, H{sup −} yield improvements which resulted from modifications to the outlet aperture assembly (applicable to both internal and external antenna sources) and studies made of the long standing problem of beam persistence with the external antenna source. The current status of the external antenna ion source will also be presented.

  1. Impact of external sources of infection on the dynamics of bovine tuberculosis in modelled badger populations

    PubMed Central

    2012-01-01

    Background The persistence of bovine TB (bTB) in various countries throughout the world is enhanced by the existence of wildlife hosts for the infection. In Britain and Ireland, the principal wildlife host for bTB is the badger (Meles meles). The objective of our study was to examine the dynamics of bTB in badgers in relation to both badger-derived infection from within the population and externally-derived, trickle-type, infection, such as could occur from other species or environmental sources, using a spatial stochastic simulation model. Results The presence of external sources of infection can increase mean prevalence and reduce the threshold group size for disease persistence. Above the threshold equilibrium group size of 6–8 individuals predicted by the model for bTB persistence in badgers based on internal infection alone, external sources of infection have relatively little impact on the persistence or level of disease. However, within a critical range of group sizes just below this threshold level, external infection becomes much more important in determining disease dynamics. Within this critical range, external infection increases the ratio of intra- to inter-group infections due to the greater probability of external infections entering fully-susceptible groups. The effect is to enable bTB persistence and increase bTB prevalence in badger populations which would not be able to maintain bTB based on internal infection alone. Conclusions External sources of bTB infection can contribute to the persistence of bTB in badger populations. In high-density badger populations, internal badger-derived infections occur at a sufficient rate that the additional effect of external sources in exacerbating disease is minimal. However, in lower-density populations, external sources of infection are much more important in enhancing bTB prevalence and persistence. In such circumstances, it is particularly important that control strategies to reduce bTB in badgers include

  2. External carbonic anhydrase in three Caribbean corals: quantification of activity and role in CO2 uptake

    NASA Astrophysics Data System (ADS)

    Tansik, Anna L.; Fitt, William K.; Hopkinson, Brian M.

    2015-09-01

    Scleractinian corals have complicated inorganic carbon ( C i) transport pathways to support both photosynthesis, by their symbiotic dinoflagellates, and calcification. The first step in C i acquisition, uptake into the coral, is critical as the diffusive boundary layer limits the supply of CO2 to the surface and HCO3 - uptake is energy intensive. An external carbonic anhydrase (eCA) on the oral surface of corals is thought to facilitate CO2 uptake by converting HCO3 - into CO2, helping to overcome the limitation imposed by the boundary layer. However, this enzyme has not yet been identified or detected in corals, nor has its activity been quantified. We have developed a method to quantify eCA activity using a reaction-diffusion model to analyze data on 18O removal from labeled C i. Applying this technique to three species of Caribbean corals ( Orbicella faveolata, Porites astreoides, and Siderastrea radians) showed that all species have eCA and that the potential rates of CO2 generation by eCA greatly exceed photosynthetic rates. This demonstrates that eCA activity is sufficient to support its hypothesized role in CO2 supply. Inhibition of eCA severely reduces net photosynthesis in all species (on average by 46 ± 27 %), implying that CO2 generated by eCA is a major carbon source for photosynthesis. Because of the high permeability of membranes to CO2, CO2 uptake is likely driven by a concentration gradient across the cytoplasmic membrane. The ubiquity of eCA in corals from diverse genera and environments suggests that it is fundamental for photosynthetic CO2 supply.

  3. Nonpoint sources as external threats to coastal water quality: lessons from Park Service experience

    USGS Publications Warehouse

    Burroughs, R.H.

    1993-01-01

    Program design for nonpoint source control was considered through an analogous problem, external threats to national parks. Nonpoint sources are diffuse land activities that degrade water quality, and recent federal legislation seeks to limit them in coastal areas. External threats occur outside a park boundary but affect the purposes for, or resources within, a park. They have been subject to federal management for many decades. Nonpoint sources are a class of external threat. Therefore, programs to limit them should consider techniques used in part protection. These park techniques include 'hard approaches', which rely on power, usually through legal devices, and 'soft approaches', which utilize shared values and objectives. A linked approach, as exemplified at the Cape Cod National Seashore, appears most promising. In a linked approach, if a soft approach fails, the manager of the protected unit is empowered to take an alternative hard action to protect the resource.

  4. Integrated Science Assessment (ISA) for Carbon Monoxide (First External Review Draft, Mar 2009)

    EPA Science Inventory

    EPA announced that the First External Review Draft of the Integrated Science Assessment (ISA) for Carbon Monoxide (CO) and related Annexes was made available for independent peer review and public review. This draft ISA document represents a concise synthesis and evaluation of th...

  5. Integrated Science Assessment (ISA) for Carbon Monoxide (Second External Review Draft, Sep 2009)

    EPA Science Inventory

    EPA announced that the Second External Review Draft of the Integrated Science Assessment (ISA) for Carbon Monoxide (CO) and related Annexes was made available for independent peer review and public review. This draft ISA document represents a concise synthesis and evaluation of t...

  6. Photosynthesis in tropical cover crop legumes influenced by irradiance, external carbon dioxide concentration and temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In plantation crops perennial tropical legumes are grown as understory plants, receive limited irradiance, and are subjected to elevated levels of CO2 and temperature. Independent short-term effects of photosynthetic photon flux density (PPFD), external carbon dioxide concentration [CO2] and temper...

  7. Computer simulations for rf design of a Spallation Neutron Source external antenna H{sup -} ion source

    SciTech Connect

    Lee, S. W.; Kang, Y. W.; Shin, K.; Welton, R. F.; Goulding, R. H.

    2010-02-15

    Electromagnetic modeling of the multicusp external antenna H{sup -} ion source for the Spallation Neutron Source (SNS) has been performed in order to optimize high-power performance. During development of the SNS external antenna ion source, antenna failures due to high voltage and multicusp magnet holder rf heating concerns under stressful operating conditions led to rf characteristics analysis. In rf simulations, the plasma was modeled as an equivalent lossy metal by defining conductivity as {sigma}. Insulation designs along with material selections such as ferrite and Teflon could be included in the computer simulations to compare antenna gap potentials, surface power dissipations, and input impedance at the operating frequencies, 2 and 13.56 MHz. Further modeling and design improvements are outlined in the conclusion.

  8. The Role of External Sources of Information in Children's Evaluative Food Categories

    ERIC Educational Resources Information Center

    Nguyen, Simone P.

    2012-01-01

    Evaluative food categories are value-laden assessments, which reflect the healthfulness and palatability of foods (e.g. healthy/unhealthy, yummy/yucky). In a series of three studies, this research examines how 3- to 4-year-old children (N?=?147) form evaluative food categories based on input from external sources of information. The results…

  9. Enhanced biological phosphorus removal with different carbon sources.

    PubMed

    Shen, Nan; Zhou, Yan

    2016-06-01

    Enhanced biological phosphorus removal (EBPR) process is one of the most economical and sustainable methods for phosphorus removal from wastewater. However, the performance of EBPR can be affected by available carbon sources types in the wastewater that may induce different functional microbial communities in the process. Glycogen accumulating organisms (GAOs) and polyphosphate accumulating organisms (PAOs) are commonly found by coexisting in the EBPR process. Predominance of GAO population may lead to EBPR failure due to the competition on carbon source with PAO without contributing phosphorus removal. Carbon sources indeed play an important role in alteration of PAOs and GAOs in EBPR processes. Various types of carbon sources have been investigated for EBPR performance. Certain carbon sources tend to enrich specific groups of GAOs and/or PAOs. This review summarizes the types of carbon sources applied in EBPR systems and highlights the roles of these carbon sources in PAO and GAO competition. Both single (e.g., acetate, propionate, glucose, ethanol, and amino acid) and complex carbon sources (e.g., yeast extract, peptone, and mixed carbon sources) are discussed in this review. Meanwhile, the environmental friendly and economical carbon sources that are derived from waste materials, such as crude glycerol and wasted sludge, are also discussed and compared.

  10. Initial tests of the Spallation Neutron Source H{sup -} ion source with an external antenna

    SciTech Connect

    Welton, R.F.; Stockli, M.P.; Murray, S.N.; Kang, Y.; Peters, J.

    2006-03-15

    The ion source for the Spallation Neutron Source (SNS) is a radio-frequency (rf) multicusp source designed to deliver H{sup -} beam pulses of 40 mA to the SNS accelerator with a normalized root-mean-square emittance of less than 0.2{pi} mm mrad, with a pulse length of 1 ms and a repetition rate of 60 Hz. In order to achieve this performance the source must operate with both high-pulse rf power, {approx}50 kW, and high average rf power, {approx}3.5 kW, over a continuous operational period of 3 weeks. During operation at these power levels the plasma-immersed, porcelain-coated rf antenna is susceptible to damage, limiting source lifetime. We are therefore developing an ion source where the plasma is separated from the Cu antenna by an Al{sub 2}O{sub 3} discharge chamber. This article describes the ion source, presents initial beam extraction measurements, and details our ongoing effort to develop this concept into a suitable ion source for the SNS.

  11. The continued development of the Spallation Neutron Source external antenna H- ion source.

    PubMed

    Welton, R F; Carmichael, J; Desai, N J; Fuga, R; Goulding, R H; Han, B; Kang, Y; Lee, S W; Murray, S N; Pennisi, T; Potter, K G; Santana, M; Stockli, M P

    2010-02-01

    The U.S. Spallation Neutron Source (SNS) is an accelerator-based, pulsed neutron-scattering facility, currently in the process of ramping up neutron production. In order to ensure that the SNS will meet its operational commitments as well as provide for future facility upgrades with high reliability, we are developing a rf-driven, H(-) ion source based on a water-cooled, ceramic aluminum nitride (AlN) plasma chamber. To date, early versions of this source have delivered up to 42 mA to the SNS front end and unanalyzed beam currents up to approximately 100 mA (60 Hz, 1 ms) to the ion source test stand. This source was operated on the SNS accelerator from February to April 2009 and produced approximately 35 mA (beam current required by the ramp up plan) with availability of approximately 97%. During this run several ion source failures identified reliability issues, which must be addressed before the source re-enters production: plasma ignition, antenna lifetime, magnet cooling, and cooling jacket integrity. This report discusses these issues, details proposed engineering solutions, and notes progress to date.

  12. Effect of Carbon and Energy Source on Bacterial Chromate Reduction

    SciTech Connect

    Smith, William Aaron; Apel, William Arnold; Petersen, J. N.; Peyton, Brent Michael

    2002-07-01

    Studies were conducted to evaluate carbon and energy sources suitable to support hexavalent chromium (Cr(VI)) reduction by a bacterial consortium enriched from dichromate-contaminated aquifer sediments. The consortium was cultured under denitrifying conditions in a minimal, synthetic groundwater medium that was amended with various individual potential carbon and energy sources. The effects of these individual carbon and energy sources on Cr(VI) reduction and growth were measured. The consortium was found to readily reduce Cr(VI) with sucrose, acetate, L-asparagine, hydrogen plus carbon dioxide, ethanol, glycerol, glycolate, propylene glycol, or D-xylose as a carbon and energy source. Minimal Cr(VI) reduction was observed when the consortium was cultured with citrate, 2-ketoglutarate, L-lactate, pyruvate, succinate, or thiosulfate plus carbon dioxide as a carbon and energy source when compared with abiotic controls. The consortium grew on all of the above carbon and energy sources, with the highest cell densities reached using D-xylose and sucrose, demonstrating that the consortium is metabolically diverse and can reduce Cr(VI) using a variety of different carbon and energy sources. The results suggest that the potential exists for the enrichment of Cr(VI)-reducing microbial populations in situ by the addition of a sucrose-containing feedstock such as molasses, which is an economical and readily available carbon and energy source.

  13. Are Glaciers and Ice Sheets Carbon Sources or Carbon Sinks?

    NASA Astrophysics Data System (ADS)

    Graly, J. A.; Drever, J. I.; Humphrey, N. F.

    2014-12-01

    Subglacial waters typically contain considerable quantities of HCO3-. Where this HCO3- is coupled with Ca2+ and Mg2+, it will ultimately precipitate as (Ca, Mg)CO3 in the oceans. If the glacial HCO3- is derived from atmospheric CO2, this pathway represents a long-term CO2 sink. If the HCO3- is derived from carbonate minerals, precipitation is equal to dissolution and there is no net effect on the CO2 balance of the atmosphere. Only the weathering of Ca or Mg-bearing silicates can potentially draw CO2 out of the ocean/atmosphere system. Subglacial environments are potential habitats for a range of microbes that may generate CO2 from organic C. If the production of CO2 from organic sources exceeds the weathering of Ca and Mg from silicates, the subglacial environment is a long-term CO2 source. In order to determine whether ice bodies typically act as CO2 sources or sinks, we modeled the evolution of pH and alkalinity through a range of typical subglacial weathering reactions, considering both the case in which CO2 and O2 can openly exchange with the atmosphere and the case in which the subglacial environment is closed from atmospheric interaction. We find that in the closed system scenario, subglacial waters cannot reach atmospheric PCO2 levels under typical conditions. Initial open system weathering followed by closed system weathering can allow CO2 supersaturation when sulfide oxidation is considered. We use this result to analyze pH and alkalinity measurements from a geographically and geologically diverse selection of subglacial waters. The PCO2 of most of the subglacial waters is near or above atmospheric values. This implies that exchange of gases between subglacial waters and the atmosphere is typical and widespread. This input of atmospheric CO2 into the glacial weathering environment implies that about 5 mg of CO2 are typically removed from the atmosphere per l of glacial discharge water. Similar PCO2 values can be produced in an entirely closed system if

  14. New Potential Sources for Black Onaping Carbon

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Becker, L.; Schultz, P. H.; Wolbach, W. S.

    1997-01-01

    One intriguing and important issue of the Sudbury Structure concerns the source of the relatively large amount of C in the Onaping Formation Black member. This dilemma was recently addressed, and the conclusion was reached that an impactor could not have delivered all of the requisite C. Becker et al. have suggested that much of the C came from the impactor and reported the presence of interstellar He "caged" inside some fullerenes that may have survived the impact. So, conceivably, the C inventory in the Sudbury Structure comes from both target and impactor materials, although the known target rocks have little C. We discuss here the possibility of two terrestrial sources for at least some of the C: (1) impact evaporation/dissociation of C from carbonate target rocks and (2) the presence of heretofore-unrecognized C-rich (up to 26 wt%) siliceous "shale," fragments, which are found in the upper, reworked Black member. Experimental: Hypervelocity impact of a 0.635-diameter Al projectile into dolomite at 5.03 km/s (performed at the Ames Research Center vertical gun range) produced a thin, black layer (= 0.05 mm thick) that partially lined the crater and coated impactor remnants. Scanning electronic microscope (SEM) imagery shows this layer to be spongelike on a submicron scale and Auger spectroscopic analyses yield: 33% C, 22% Mg, 19% 0, and 9% Al (from the projectile). Elemental mapping shows that all of the available 0 is combined with Ca and Mg, Al is not oxidized, and C is in elemental form. Dissociation efficiency of C from CO2 is estimated to be <10% of crater volume. Raman spectroscopy indicates that the C is highly disorganized graphite. Another impact experiment [4] also produced highly disordered graphite from a limestone target (reducing collector), in addition to small amounts of diamond/lonsdaleite/chaoite (oxidizing collector). These experiments confirm the reduction of C from carbonates in impact vapor plumes. Observational: SEM observations and

  15. Diagnostic Evaluation of Carbon Sources in CMAQ

    EPA Science Inventory

    Traditional monitoring networks measure only total elemental carbon (EC) and organic carbon (OC) routinely. Diagnosing model biases with such limited information is difficult. Measurements of organic tracer compounds have recently become available and allow for more detailed di...

  16. Direct growth of carbon nanotubes on metal surfaces without an external catalyst and nanocomposite production

    NASA Astrophysics Data System (ADS)

    Baddour, Carole Emilie

    The research work presented in this thesis deals with carbon nanotubes (CNTs), an allotrope of carbon with a cylindrical structure consisting of a rolled up graphene sheet. CNTs are generally produced by the decomposition of a carbon source in the presence of a metal catalyst at elevated temperatures. CNTs have outstanding properties and have attracted immense attention in both industry and academia. However, the development of commercial applications of CNTs is slow due to limitations in the large scale production of CNTs and their high cost. Another limitation is the interface resistance generated by external catalyst nanoparticles used in traditional CNT growth methods. In order to eliminate the interface resistance and simultaneously provide CNT growth over large surfaces and varying geometries, a method called direct CNT growth is established to enable the extraction of the CNT structure directly from the metal surface. The novel process for the production of CNTs developed in the present thesis is applied to planar surfaces and spherical particles made of stainless steel (SS) 304. The method is based on the establishment of nanometer scale structures at the surface which act as catalyst nanoparticles while at the same time being integral parts of the material. It uses first a mild chemical etching of the surface, followed by a specific heat treatment performed using either standard chemical vapour deposition (standard-CVD) or fluidized bed CVD (FBCVD) techniques. Acetylene (C2H2) is used as the carbon source and SS 304 acts as both the catalyst and the substrate in the growth process. This direct CNT growth with this substrate dual function eliminates the need of external catalyst nanoparticles deposited onto the surface. The active sites necessary for CNT growth are tailored on the SS itself by means of the two-step treatment process. MWNTs of 20-70 nm in diameter are produced. The CNTs are characterized by Raman Spectroscopy, Thermogravimetric analysis (TGA

  17. The status of the SNS external antenna ion source and spare RFQ test facility

    SciTech Connect

    Welton, R. F. Aleksandrov, A. V.; Han, B. X.; Kang, Y.; Murray, S. N.; Pennisi, T. R.; Piller, C.; Santana, M.; Stockli, M. P.; Dudnikov, V. G.

    2016-02-15

    The Oak Ridge National Laboratory operates the Spallation Neutron Source, consisting of a H{sup −} ion source, a 1 GeV linac and an accumulator ring. The accumulated <1 μs-long, ∼35 A beam pulses are extracted from the ring at 60 Hz and directed onto a liquid Hg target. Spalled neutrons are directed to ∼20 world class instruments. Currently, the facility operates routinely with ∼1.2 MW of average beam power, which soon will be raised to 1.4 MW. A future upgrade with a second target station calls for raising the power to 2.8 MW. This paper describes the status of two accelerator components expected to play important roles in achieving these goals: a recently acquired RFQ accelerator and the external antenna ion source. Currently, the RFQ is being conditioned in a newly constructed 2.5 MeV Integrated Test Facility (ITF) and the external antenna source is also being tested on a separate test stand. This paper presents the results of experiments and the testing of these systems.

  18. The status of the SNS external antenna ion source and spare RFQ test facility

    NASA Astrophysics Data System (ADS)

    Welton, R. F.; Aleksandrov, A. V.; Dudnikov, V. G.; Han, B. X.; Kang, Y.; Murray, S. N.; Pennisi, T. R.; Piller, C.; Santana, M.; Stockli, M. P.

    2016-02-01

    The Oak Ridge National Laboratory operates the Spallation Neutron Source, consisting of a H- ion source, a 1 GeV linac and an accumulator ring. The accumulated <1 μs-long, ˜35 A beam pulses are extracted from the ring at 60 Hz and directed onto a liquid Hg target. Spalled neutrons are directed to ˜20 world class instruments. Currently, the facility operates routinely with ˜1.2 MW of average beam power, which soon will be raised to 1.4 MW. A future upgrade with a second target station calls for raising the power to 2.8 MW. This paper describes the status of two accelerator components expected to play important roles in achieving these goals: a recently acquired RFQ accelerator and the external antenna ion source. Currently, the RFQ is being conditioned in a newly constructed 2.5 MeV Integrated Test Facility (ITF) and the external antenna source is also being tested on a separate test stand. This paper presents the results of experiments and the testing of these systems.

  19. Automatic external filling for the ion source gas bottle of a Van de Graaff accelerator

    NASA Astrophysics Data System (ADS)

    Strivay, D.; Bastin, T.; Dehove, C.; Dumont, P. D.; Marchal, A.; Garnir, H.; Weber, G.

    1997-09-01

    We describe a fully automatic system we developed to fill, from an external gas bottle, the ion source terminal gas storage bottle of a 2 MV Van de Graaff accelerator without depressing the 25 bar insulating gas. The system is based on a programmable automate ordering electropneumatical valves. The only manual operation is the connection of the external gas cylinder. The time needed for a gas change is reduced to typically 15 min (depending on the residual pressure wished for the gas removed from the terminal bottle). To check this system we study the ionic composition of the ion beam delivered by our accelerator after different gas changes. The switching magnet of our accelerator was used to analyse the ionic composition of the accelerated beams in order to verify the degree of elimination of the previous gases in the system.

  20. Source attribution of black carbon in Arctic snow.

    PubMed

    Hegg, Dean A; Warren, Stephen G; Grenfell, Thomas C; Doherty, Sarah J; Larson, Timothy V; Clarke, Antony D

    2009-06-01

    Snow samples obtained at 36 sites in Alaska, Canada, Greenland, Russia, and the Arctic Ocean in early 2007 were analyzed for light-absorbing aerosol concentration together with a suite of associated chemical species. The light absorption data, interpreted as black carbon concentrations, and other chemical data were input into the EPA PMF 1.1 receptor model to explore the sources for black carbon in the snow. The analysis found four factors or sources: two distinct biomass burning sources, a pollution source, and a marine source. The first three of these were responsible for essentially all of the black carbon, with the two biomass sources (encompassing both open and closed combustion) together accounting for >90% of the black carbon.

  1. Towards a Carbon Nanotube Ionization Source for Planetary Atmosphere Exploration

    NASA Astrophysics Data System (ADS)

    Oza, A. V.; Leblanc, F.; Berthelier, J. J.; Becker, J.; Coulomb, R.; Gilbert, P.; Hong, N. T.; Lee, S.; Vettier, L.

    2015-12-01

    The characterization of planetary exospheres today, relies on the development of a highly efficient ionization source, due to the scant neutral molecules (n < 108 cm -3) present in diffuse planetary coronae. These tenuous atmospheres provide insight on to physical processes known to occur such as: space weathering, magneto-atmosphere interactions, as well as atmospheric escape mechanisms, all of which are being heavily investigated via current 3D Monte Carlo simulations (Turc et al. 2014, Leblanc et al. 2016 in prep) at LATMOS. Validation of these studies will rely on in-situ observations in the coming decades. Neutral detection strongly depends on electron-impact ionization which via conventional cathode-sources, such as thermal filaments (heated up to 2000 K), may only produce the target ionization essential for energy-measurements with large power consumption. Carbon nanotubes (CNTs) however are ideal low-power, cold cathodes, when subject to moderate electric fields (E ~ 1 MV / m). We present our current device, a small CNT chip, of emission area 15 mm2, emitting electrons that pass through an anode grid and subsequent electrostatic analyzer. The device currently extracts hundreds of µAmperes with applied external voltages ~ -150 Volts, approaching minimum power consumption < 0.1 Watts. The 3D modeling of field effect electrons ionizing a standard influx of neutrals is shown, using the multiphysics suite COMSOL. To better anticipate the species an ideal in-situ spacecraft equipped with such an ionization source would observe, we discuss Europa's exosphere. Europa's environment is largely shaped by the Jovian plasma sputtering the icy regolith with heavy ions and electrons (keV < E < MeV), producing predominately molecular oxygen (Johnson et al. 2002).

  2. External magnetic field-induced mesoscopic organization of Fe3O4 pyramids and carbon sheets.

    PubMed

    Pol, S V; Pol, V G; Gedanken, A; Felner, I; Sung, M-G; Asai, S

    2007-06-11

    The current investigation is centered on the thermal decomposition of iron(II) acetyl acetonate, Fe(C5H7O2)2, in a closed cell at 700 degrees C, which is conducted under a magnetic field (MF) of 10 T. The product is compared with a similar reaction that was carried out without a MF. This article shows how the reaction without a MF produces spherical Fe3O4 particles coated with carbon. The same reaction in the presence of a 10 T MF causes the rejection of the carbon from the surface of pyramid-shaped Fe3O4 particles, increases the Fe3O4 particle diameter, forms separate carbon particles, and leads to the formation of an anisotropic (long cigarlike) orientation of Fe3O4 pyramids and C sheets. The macroscopic orientation of Fe3O4 pyramids+C sheets is stable even after the removal of an external MF. The suggested process can be used to fabricate large arrays of uniform wires comprised of some magnetic nanoparticles, and to improve the magnetic properties of nanoscale magnetic materials. The probable mechanism is developed for the growth and assembly behavior of magnetic Fe3O4 pyramids+C sheets under an external MF. The effect of an applied MF to synthesize morphologically different, but structurally the same, products with mesoscopic organization is the key theme of the present paper.

  3. A comparison of black carbon measurement methods for combustion sources

    NASA Astrophysics Data System (ADS)

    Holder, A. L.; Pavlovic, J.; Yelverton, T.; Hagler, G.; Aurell, J.; Ebersviller, S.; Seay, B.; Jetter, J.; Gullett, B.; Hays, M. D.

    2015-12-01

    Black carbon is an important short-term climate forcer that has been linked with adverse health effects. Multiple black carbon measurement methodologies exist, but no standard measurement method or calibration material has been agreed upon. Moreover, the U.S. Environmental Protection Agency uses elemental carbon in its ambient monitoring networks and in its emissions inventory, assuming that elemental carbon is equivalent to black carbon. Instrument comparisons with ambient aerosols have demonstrated considerable differences between black carbon and elemental carbon, as well as among different black carbon measurements. However, there have been few published comparable studies for source emissions. We used multiple measurement methods to quantify black carbon and elemental carbon emissions from a range of combustion sources (diesel gensets, coal fired boilers, prescribed fires and cookstoves) emitting particles of varying composition and physical characteristics. The ratio of black carbon to elemental carbon (BC/EC) ranged from 0.50 to 2.8 and depended upon the combustion source. The greatest agreement was observed for emissions from cookstoves (BC/EC = 1.1 ± 0.3). The largest differences were seen for emissions from large stationary diesel genset (BC/EC = 2.3 ± 0.5) and were most pronounced when a diesel particulate filter was used (BC/EC 2.5 ± 0.6). This suggests that this source category may be underrepresented in emissions inventories based on elemental carbon. Black carbon concentrations derived from filter-based attenuation were highly correlated with photo-acoustic absorption measurements, but were generally 50% greater. This is likely due to the choice of calibration factor, which is currently ambiguously defined. These results highlight the importance of developing a standard calibration material to improve comparability among measurements.

  4. Growth of graphene films from non-gaseous carbon sources

    DOEpatents

    Tour, James; Sun, Zhengzong; Yan, Zheng; Ruan, Gedeng; Peng, Zhiwei

    2015-08-04

    In various embodiments, the present disclosure provides methods of forming graphene films by: (1) depositing a non-gaseous carbon source onto a catalyst surface; (2) exposing the non-gaseous carbon source to at least one gas with a flow rate; and (3) initiating the conversion of the non-gaseous carbon source to the graphene film, where the thickness of the graphene film is controllable by the gas flow rate. Additional embodiments of the present disclosure pertain to graphene films made in accordance with the methods of the present disclosure.

  5. Shunting arc plasma source for pure carbon ion beama)

    NASA Astrophysics Data System (ADS)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y.

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA/mm2 at the peak of the pulse.

  6. Shunting arc plasma source for pure carbon ion beam.

    PubMed

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse.

  7. Packaged heterodyne source modules based on external cavity lasers for microwave applications

    NASA Astrophysics Data System (ADS)

    Chuyanov, Vadim; Kupershmidt, Vladimir; Kusnadi, Frans; Plaessmann, Henry; Ozcan, Meric

    2005-03-01

    External cavity lasers (ECL) based on semiconductor diode gain elements and Fiber Bragg Gratings (FBG) have been developed for Telecom (OC-48) nd Analog (CATV, QAM) applications. They possess very narrow linewidth (100 kHz) and exceptional wavelength stability. These qualities makes them attractive platform for implementation of heterodyne sources and Optical Phase Locked Loops (OPLL) for Microwave Photonics applications. We discuss two types of such heterodyne sources: heterodyne oscillator based on heterodyning of two ECL, and fixed frequency heterodyne oscillators based on ECL with FBG written in the polarization maintaining fiber. All two types of heterodyne sources were built based on industry standard 14-pin butterfly package. All of them exhibited excellent wavelength stability (less than 1 pm/mA and 1-2 pm/°C). Fixed frequency sources provided beat oscillation around 40 GHz. We present performance characteristics and measurement data on (linewidth, phase noise, heterodyne mixing, etc.) and discuss the merits of ECL use as heterodyne sources for Microwave Photonics applications.

  8. Carbon reactivation by externally-fired rotary kiln furnace. Final report Oct 75-Jan 78

    SciTech Connect

    Chen, C.; Directo, L.S.

    1980-08-01

    An externally-fired rotary kiln furnace system has been evaluated for cost-effectiveness in carbon reactivation at the Pomona Advanced Wastewater Treatment Research Facility. The pilot scale rotary kiln furnace was operated within the range of 682 kg/day (1,500 lb/day) to 909 kg/day (2,000 lb/day). The rotary kiln furnace was found to be as effective as the multiple hearth furnace in reactivating the exhausted granular activated carbon. The operating and maintenance of the rotary kiln system required less operator skill than the multiple hearth furnace system. However, the corrosion rate was higher in the rotary tube than in the multiple hearth furnace. Cost estimates based on a typical regeneration capacity of 182 kg/hr (400 lb/hr) have been made for both rotary kiln and multiple hearth furnace systems. These indicate that the capital cost for the multiple hearth furnace is about two times that of the rotary kiln furnace. The operation and maintenance costs for both furnace systems are similar. The overall process costs for the multiple hearth and rotary kiln furnace systems are estimated to be 33.2 cents/kg (15.1 cents/lb) of carbon regenerated and 29.2 cents/kg (13.3 cents/lb) of carbon regenerated, respectively.

  9. Carbon and Energy Sources for the Nitrifying Autotroph Nitrobacter

    PubMed Central

    Delwiche, C. C.; Finstein, M. S.

    1965-01-01

    Delwiche, C. C. (University of California, Davis), and M. S. Finstein. Carbon and energy sources for the nitrifying autotroph Nitrobacter. J. Bacteriol. 90:102–107. 1965.—The effect of various organic compounds on the growth and metabolism of the obligatively autotrophic nitrifying organism Nitrobacter was studied. A slight stimulation of both nitrification and growth was obtainable with a number of organic amendments, including yeast extract, Vitamin Free Casamino Acids, and some amino acids. Depending upon culture conditions, a strong stimulation of growth was obtained with acetate as an amendment to the culture solution. Several compounds, including valine, hydroxyproline, and threonine, were inhibitory at concentrations of 10−3m. The incorporation of carbon from isotopically labeled organic compounds was demonstrated. Acetate and glycine were particularly strong contributors to cell carbons. These could not substitute for carbon dioxide as a sole carbon source for growth, however, nor could any other of the carbon compounds that were tried. PMID:16562002

  10. Enhanced life ion source for germanium and carbon ion implantation

    SciTech Connect

    Hsieh, Tseh-Jen; Colvin, Neil; Kondratenko, Serguei

    2012-11-06

    Germanium and carbon ions represent a significant portion of total ion implantation steps in the process flow. Very often ion source materials that used to produce ions are chemically aggressive, especially at higher temperatures, and result in fast ion source performance degradation and a very limited lifetime [B.S. Freer, et. al., 2002 14th Intl. Conf. on Ion Implantation Technology Proc, IEEE Conf. Proc., p. 420 (2003)]. GeF{sub 4} and CO{sub 2} are commonly used to generate germanium and carbon beams. In the case of GeF{sub 4} controlling the tungsten deposition due to the de-composition of WF{sub 6} (halogen cycle) is critical to ion source life. With CO{sub 2}, the materials oxidation and carbon deposition must be controlled as both will affect cathode thermionic emission and anti-cathode (repeller) efficiencies due to the formation of volatile metal oxides. The improved ion source design Extended Life Source 3 (Eterna ELS3) together with its proprietary co-gas material implementation has demonstrated >300 hours of stable continuous operation when using carbon and germanium ion beams. Optimizing cogas chemistries retard the cathode erosion rate for germanium and carbon minimizes the adverse effects of oxygen when reducing gas is introduced for carbon. The proprietary combination of hardware and co-gas has improved source stability and the results of the hardware and co-gas development are discussed.

  11. Impact of external industrial sources on the regional and local air quality of Mexico Megacity

    NASA Astrophysics Data System (ADS)

    Almanza, V. H.; Molina, L. T.; Li, G.; Fast, J.; Sosa, G.

    2013-10-01

    The air quality of megacities can be influenced by external emissions sources on both global and regional scale, and at the same time their outflow emissions can exert an important impact to the surrounding environment. The present study evaluates an SO2 peak observed on 24 March 2006 at the suburban supersite T1 and ambient air quality monitoring stations located in the north region of the Mexico City Metropolitan Area (MCMA) during MILAGRO campaign. We found that this peak could be related to an important episodic emission event from Tizayuca region, northeast of the MCMA. Back trajectories analyses suggest that the emission event started in the early morning at 04:00 LST and lasted for about 9 h. The estimated emission rate is noticeably high, about 2 kg s-1. This finding suggests the possibility of "overlooked" emission sources in this region that could influence the air quality of the MCMA. This further motivated us to study the cement plants, including those in the State of Hidalgo and in the State of Mexico, and we found that they can contribute in the NE region of the basin (about 41.7%), at the suburban supersite T1 (41.23%) and at some monitoring stations their contribution can be even higher than from the Tula Industrial Complex. The contribution of Tula Industrial Complex to regional ozone levels is estimated. The model suggests low contribution to the MCMA (1 ppb to 4 ppb) and slightly higher at the suburban T1 (6 ppb) and rural T2 (5 ppb) supersites. However, the contribution could be as high as 10 ppb in the upper northwest region of the basin and in the southwest and south-southeast regions of State of Hidalgo. In addition, a first estimate of the potential contribution from flaring activities to regional ozone levels is presented. Emission rates are estimated with a CFD combustion model. Results suggest that up to 30% of the total regional ozone from TIC could be related to flaring activities. Finally, the influence in SO2 levels from technological

  12. Source contributions to atmospheric fine carbon particle concentrations

    NASA Astrophysics Data System (ADS)

    Andrew Gray, H.; Cass, Glen R.

    A Lagrangian particle-in-cell air quality model has been developed that facilitates the study of source contributions to atmospheric fine elemental carbon and fine primary total carbon particle concentrations. Model performance was tested using spatially and temporally resolved emissions and air quality data gathered for this purpose in the Los Angeles area for the year 1982. It was shown that black elemental carbon (EC) particle concentrations in that city were dominated by emissions from diesel engines including both on-highway and off-highway applications. Fine primary total carbon particle concentrations (TC=EC+organic carbon) resulted from the accumulation of small increments from a great variety of emission source types including both gasoline and diesel powered highway vehicles, stationary source fuel oil and gas combustion, industrial processes, paved road dust, fireplaces, cigarettes and food cooking (e.g. charbroilers). Strategies for black elemental carbon particle concentration control will of necessity need to focus on diesel engines, while controls directed at total carbon particle concentrations will have to be diversified over a great many source types.

  13. External influences on Europe's air quality: Baseline methane, carbon monoxide and ozone from 1990 to 2030 at Mace Head, Ireland

    NASA Astrophysics Data System (ADS)

    Derwent, R. G.; Simmonds, P. G.; O'Doherty, S.; Stevenson, D. S.; Collins, W. J.; Sanderson, M. G.; Johnson, C. E.; Dentener, F.; Cofala, J.; Mechler, R.; Amann, M.

    A global 3-D chemistry-transport model STOCHEM has been employed to study trends in the mole fractions of methane, carbon monoxide and ozone in baseline air masses entering Europe from the Atlantic Ocean over the period from 1990 to 2030. With a range of emission scenarios for man-made ozone precursor emission sources available, a wide range of model trends were predicted for the period up to 2030. In the scenario based on current planned air pollution controls, IIASA CLE, methane shows a strong upward trend, ozone shows a weaker upward trend, and carbon monoxide is approximately flat in baseline air masses. In one of the more pessimistic IPCC SRES scenarios, A2, all three gases show future increases. However, in the scenario based on maximum feasible emission reductions, IIASA MFR all three trace gases decline. By 2030, projected climate change reduces the growth in CH 4, but has insignificant effects on baseline CO and O 3 in these simulations. Global or hemispheric ozone precursor emissions and their controls exert a potentially large external influence on Europe's air quality. This influence is currently not taken into account in future European air quality policy formulation.

  14. Spatiotemporal optical similaritons in dual-core waveguide with an external source

    NASA Astrophysics Data System (ADS)

    Soloman Raju, Thokala

    2017-04-01

    We explore analytically and numerically the existence of exact asymptotic spatiotemporal optical self-similar light bullets to the nonlinear Schrödinger equation with gain in the presence of an external source in (3+1)-dimensions. This model appertains to the description of self-similar wave propagation through asymmetric planar dual-core waveguide (DWG) amplifiers. The asymmetric DWG is composed of two adjoining, closely spaced, upper and lower waveguides, in which the lower one acts as a passive waveguide while the upper waveguide is an active one. Due to the linear coupling between them, we can control the dynamical behaviors of the wave propagating through the passive waveguide by controlling the wave in active waveguide. We explicate the mechanism to control the dynamical behaviors of these self-similar waves for two specific cases: (i) when the gain and width are hyperbolic functions and (ii) when the gain and width are periodic functions.

  15. Optical similaritons in a tapered graded-index nonlinear-fiber amplifier with an external source

    SciTech Connect

    Raju, Thokala Soloman; Panigrahi, Prasanta K.

    2011-09-15

    We analytically explore a wide class of optical similariton solutions to the nonlinear Schroedinger equation appropriately modified to model beam propagation in a tapered, graded-index nonlinear-fiber amplifier with an external source. Under certain physical conditions, we reduce the coupled nonlinear Schroedinger equations to a single-wave equation that aptly describes similariton propagation through asymmetric twin-core fiber amplifiers. The asymmetric twin-core fiber is composed of two adjoining, closely spaced, single-mode fibers in which the active one is a tapered, graded-index nonlinear-fiber and the passive one is a step-index fiber. We obtain these self-similar waves for different choices of tapered index profile, using a Moebius transformation. Our procedure is applicable for both self-focusing and self-defocusing nonlinearities.

  16. Statistical addition method for external noise sources affecting HF-MF-LF systems

    NASA Astrophysics Data System (ADS)

    Neudegg, David

    2001-01-01

    The current statistical method for the addition of external component noise sources in the LF, MF, and lower HF band (100 kHz to 3 MHz) produces total median noise levels that may be less than the largest-component median in some cases. Several case studies illustrate this anomaly. Methods used to sum the components rely on their power (decibels) distributions being represented as normal by the statistical parameters. The atmospheric noise component is not correctly represented by its decile values when it is assumed to have a normal distribution, causing anomalies in the noise summation when components are similar in magnitude. A revised component summation method is proposed, and the way it provides a more physically realistic total noise median for LF, MF, and lower HF frequencies is illustrated.

  17. Allothermal gasification of biomass using micron size biomass as external heat source.

    PubMed

    Cheng, Gong; Li, Qian; Qi, Fangjie; Xiao, Bo; Liu, Shiming; Hu, Zhiquan; He, Piwen

    2012-03-01

    An allothermal biomass gasification system using biomass micron fuel (BMF) as external heat source was developed. In this system, heat supplied to gasifier was generated from combustion of BMF. Biomass feedstock was gasified with steam and then tar in the produced gas was decomposed in a catalytic bed with NiO/γ-Al(2)O(3) catalyst. Finally the production gas was employed as a substitute for civil fuel gas. An overall energy analysis of the system was also investigated. The results showed that the lower heating value of the product gas reached more than 12 MJ/Nm(3). The combusted BMF accounted for 26.8% of the total energy input. Allothermal gasification based on the substituted BMF for conventional energy was an efficient and economical technology to obtain bioenergy.

  18. AN EXTERNAL ORIGIN FOR CARBON MONOXIDE ON URANUS FROM HERSCHEL/SPIRE?

    SciTech Connect

    Teanby, N. A.; Irwin, P. G. J. E-mail: irwin@atm.ox.ac.uk

    2013-10-01

    Previous studies have demonstrated an external source of CO on Jupiter, Saturn, and Neptune. However, it has not been possible to demonstrate this on Uranus because of its low CO abundance, low upper-tropospheric temperatures, and low stratospheric thermal gradient, which make detection very challenging. Here we use 17 Herschel/SPIRE observation sequences spanning 3 yr (2009-2012), which cover 14.6-51.8 cm{sup –1} with a combined integration time of 5 hr. These spectra were originally taken for routine calibration purposes, so were corrected for continuum offsets prior to analysis. The final stacked spectra had an extremely low noise level of 10-50 pW cm{sup –2} sr{sup –1}/cm{sup –1}. Despite this, CO was not observed, but we were able to obtain stringent 3σ upper limits at the 0.1-0.2 bar level of 2.1 ppb for a uniform profile, and 9.4 ppb for a stratosphere-only profile—an order of magnitude improvement over previous studies. Comparison with observed CO fluorescence by Encrenaz et al. suggests the majority of Uranus' stratospheric CO has an external origin. It thus appears that external supply of oxygen species—via comets, micrometeorites, or dust—is an important process on all giant planets in our solar system.

  19. Distinguishing internal and external sediment sources in a tidal freshwater wetland, the Netherlands

    NASA Astrophysics Data System (ADS)

    van der Deijl, Eveline C.; van der Perk, Marcel; Kik, Nanda J.; Verschelling, Eelco; Middelkoop, Hans

    2015-04-01

    Many deltas across the globe suffer from drowning due to sea level rise or land subsidence in combination with sediment starvation. The process of drowning can be attenuated by enhancing sediment inputs or the sediment trapping efficiency of deltas. To examine the sediment budget of delta areas based on measurements of sediment deposition, it is essential to distinguish the sediment that has entered the area from upstream areas from sediment that has been redistributed within the area. This pilot study aims to explore the prospects to distinguish between external and internal sediment sources based on the geochemical composition of the sediment deposited. This study was carried out in the Kleine Noordwaard, which is part of the Brabantse Biesbosch, a former inland delta located in-between the Rhine and Meuse rivers in the south-western part of the Netherlands. A significant part of this area has been embanked and turned into polder areas in the early 19th century. In contrast to many tidal creeks and flats, the polder areas have not received inputs of severely contaminated river sediment between the 1930s and 1980s. A number of polders have recently or are currently being de-poldered again, i.e. converted from agricultural polder land into an inundated tidal freshwater wetland, in order to increase the conveyance capacity of the Rhine River during extreme discharge situations, thereby lowering the peak water levels upstream and to enhance the nature values of the area. The external and internal sediment sources of the sediment deposited in the Kleine Noordwaard could be discriminated based on the zinc (Zn) and rubidium (Rb) concentrations. These two elements exhibit a different linear relation for the more contaminated external sediment originating from the Rhine River and the less contaminated, internally redistributed sediment originating from the topsoil of the former polder area. The mixture proportion for each sediment sample could not be directly derived

  20. Effects of iron and calcium carbonate on the variation and cycling of carbon source in integrated wastewater treatments.

    PubMed

    Zhimiao, Zhao; Xinshan, Song; Yufeng, Zhao; Yanping, Xiao; Yuhui, Wang; Junfeng, Wang; Denghua, Yan

    2017-02-01

    Iron and calcium carbonate were added in wastewater treatments as the adjusting agents to improve the contaminant removal performance and regulate the variation of carbon source in integrated treatments. At different temperatures, the addition of the adjusting agents obviously improved the nitrogen and phosphorous removals. TN and TP removals were respectively increased by 29.41% and 23.83% in AC-100 treatment under 1-day HRT. Carbon source from dead algae was supplied as green microbial carbon source and Fe(2+) was supplied as carbon source surrogate. COD concentration was increased to 30mg/L and above, so the problem of the shortage of carbon source was solved. Dead algae and Fe(2+) as carbon source supplement or surrogate played significant role, which was proved by microbial community analysis. According to the denitrification performance in the treatments, dead algae as green microbial carbon source combined with iron and calcium carbonate was the optimal supplement carbon source in wastewater treatment.

  1. An oscillator in a carbon peapod controllable by an external electric field: a molecular dynamics study.

    PubMed

    Wang, Min; Li, Chang Ming

    2010-01-22

    We investigate the peapod structure of C(59)N(+)@(10, 10) single-walled carbon nanotubes by simulation, and discover that the ball initial velocity could be controlled by the external impulse electric field, then becoming an oscillator, of which the period could be tuned in a relatively large range of 80-18 ps by adjusting the ball motion in the initial stage. The SWNT length could also be used to tune the period of the oscillator. Based on these results, two potential devices, controllable period and constant period systems are proposed. For the first device, the ball motion is adjusted step by step and the period decreases from 80-100 ps to 18-20 ps or increases from 18-20 ps to 80-100 ps. For the second one, a relatively high constant period within 20-25 ps could be controlled by applying a much longer period signal generator (1 ns) from the external electric field, indicating a robust signal magnification.

  2. Denitrification of high nitrate concentration wastewater using alternative carbon sources.

    PubMed

    Fernández-Nava, Y; Marañón, E; Soons, J; Castrillón, L

    2010-01-15

    The use of different organic carbon sources in the denitrification of wastewater containing 2500 mg nitrates/L in a SBR was studied. Three alternative sources of carbon were tested: wastewater from a sweet factory, a residue from a soft drinks factory and a residue from a dairy plant. The first two are sugar-rich, whereas the third presents a high content in lactic acid. Maximum specific denitrification rates of between 42 and 48 mg NO(3)-N/g VSS h were obtained. The effluents were nitrate-free and very low COD concentrations were obtained in 4-6h reaction time, especially with the sugar-rich carbon sources. The values of the denitrifier net yield coefficient were higher than when using methanol (0.93-1.75 g VSS(formed)/g NO(x)-N(reduced)). The lowest value was obtained using the lactic acid-rich residue. The optimum COD/N ratios varied between 4.6 for the lactic acid-rich carbon source and 5.5-6.5 for the sugar-rich carbon sources.

  3. IMPROVING SOURCE PROFILES AND APPORTIONMENT OF COMBUSTION SOURCES USING THERMAL CARBON FRACTIONS IN MULTIVARIATE RECEPTOR MODELS

    EPA Science Inventory

    The purpose of this study was to improve combustion source profiles and apportionment of a PM2.5 urban aerosol by using 7 individual organic and elemental carbon thermal fractions in place of total organic and elemental carbon. This study used 3 years (96-99) of speciated data...

  4. Elucidating carbon sources driving microbial metabolism during oil sands reclamation.

    PubMed

    Bradford, Lauren M; Ziolkowski, Lori A; Goad, Corey; Warren, Lesley A; Slater, Gregory F

    2017-03-01

    Microbial communities play key roles in remediation and reclamation of contaminated environments via biogeochemical cycling of organic and inorganic components. Understanding the trends in in situ microbial community abundance, metabolism and carbon sources is therefore a crucial component of effective site management. The focus of this study was to use radiocarbon analysis to elucidate the carbon sources driving microbial metabolism within the first pilot wetland reclamation project in the Alberta oil sands region where the observation of H2S had indicated the occurrence of microbial sulphate reduction. The reclamation project involved construction of a three compartment system consisting of a freshwater wetland on top of a sand cap overlying a composite tailings (CT) deposit. Radiocarbon analysis demonstrated that both dissolved and sediment associated organic carbon associated with the deepest compartments (the CT and sand cap) was primarily fossil (Δ(14)C = -769 to -955‰) while organic carbon in the overlying peat was hundreds to thousands of years old (Δ(14)C = -250 to -350‰). Radiocarbon contents of sediment associated microbial phospholipid fatty acids (PLFA) were consistent with the sediment bulk organic carbon pools (Peat: Δ(14)CPLFA = -257‰; Sand cap Δ(14)CPLFA = -805‰) indicating that these microbes were using sediment associated carbon. In contrast, microbial PLFA grown on biofilm units installed in wells within the deepest compartments contained much more modern carbon that the associated bulk carbon pools. This implied that the transfer of relatively more modern carbon was stimulating the microbial community at depth within the system. Correlation between cellular abundance estimates based on PLFA concentrations and the Δ(14)CPLFA indicated that the utilization of this more modern carbon was stimulating the microbial community at depth. These results highlight the importance of understanding the occurrence and potential outcomes

  5. Carbon-14 in methane sources and in atmospheric methane - The contribution from fossil carbon

    NASA Technical Reports Server (NTRS)

    Wahlen, M.; Tanaka, N.; Henry, R.; Deck, B.; Zeglen, J.

    1989-01-01

    Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in clean air samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, peat bogs, rice fields, and tundra, is somewhat depleted in carbon-14. Atmospheric (C-14)H4 seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 + or - 0.8 percent modern carbon in the Northern Hemisphere and 120.0 + or - 0.7 percent modern carbon in the Southern Hemisphere.

  6. Carbon-14 in methane sources and in atmospheric methane - The contribution from fossil carbon

    NASA Astrophysics Data System (ADS)

    Wahlen, M.; Tanaka, N.; Henry, R.; Deck, B.; Zeglen, J.

    1989-07-01

    Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in clean air samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, peat bogs, rice fields, and tundra, is somewhat depleted in carbon-14. Atmospheric (C-14)H4 seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 + or - 0.8 percent modern carbon in the Northern Hemisphere and 120.0 + or - 0.7 percent modern carbon in the Southern Hemisphere.

  7. Modeling external carbon addition in biological nutrient removal processes with an extension of the international water association activated sludge model.

    PubMed

    Swinarski, M; Makinia, J; Stensel, H D; Czerwionka, K; Drewnowski, J

    2012-08-01

    The aim of this study was to expand the International Water Association Activated Sludge Model No. 2d (ASM2d) to account for a newly defined readily biodegradable substrate that can be consumed by polyphosphate-accumulating organisms (PAOs) under anoxic and aerobic conditions, but not under anaerobic conditions. The model change was to add a new substrate component and process terms for its use by PAOs and other heterotrophic bacteria under anoxic and aerobic conditions. The Gdansk (Poland) wastewater treatment plant (WWTP), which has a modified University of Cape Town (MUCT) process for nutrient removal, provided field data and mixed liquor for batch tests for model evaluation. The original ASM2d was first calibrated under dynamic conditions with the results of batch tests with settled wastewater and mixed liquor, in which nitrate-uptake rates, phosphorus-release rates, and anoxic phosphorus uptake rates were followed. Model validation was conducted with data from a 96-hour measurement campaign in the full-scale WWTP. The results of similar batch tests with ethanol and fusel oil as the external carbon sources were used to adjust kinetic and stoichiometric coefficients in the expanded ASM2d. Both models were compared based on their predictions of the effect of adding supplemental carbon to the anoxic zone of an MUCT process. In comparison with the ASM2d, the new model better predicted the anoxic behaviors of carbonaceous oxygen demand, nitrate-nitrogen (NO3-N), and phosphorous (PO4-P) in batch experiments with ethanol and fusel oil. However, when simulating ethanol addition to the anoxic zone of a full-scale biological nutrient removal facility, both models predicted similar effluent NO3-N concentrations (6.6 to 6.9 g N/m3). For the particular application, effective enhanced biological phosphorus removal was predicted by both models with external carbon addition but, for the new model, the effluent PO4-P concentration was approximately one-half of that found from

  8. Production of biodiesel from carbon sources of macroalgae, Laminaria japonica.

    PubMed

    Xu, Xu; Kim, Ji Young; Oh, Yu Ri; Park, Jong Moon

    2014-10-01

    As aquatic biomass which is called "the third generation biomass", Laminaria japonica (also known as Saccharina japonica) consists of mannitol and alginate which are the main polysaccharides of algal carbohydrates. In this study, oleaginous yeast (Cryptococcus curvatus) was used to produce lipid from carbon sources derived from Laminaria japonica. Volatile fatty acids (VFAs) were produced by fermentation of alginate extracted from L. japonica. Thereafter, mannitol was mixed with VFAs to culture the oleaginous yeast. The highest lipid content was 48.30%. The composition of the fatty acids was similar to vegetable oils. This is the first confirmation of the feasibility of using macroalgae as a carbon source for biodiesel production.

  9. USE OF FATTY ACID STABLE CARBON ISOTOPE RATIO TO INDICATE MICROBIAL CARBON SOURCE IN TROPICAL SOILS

    EPA Science Inventory


    We use measurements of the concentration and stable carbon isotope ratio of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels, broad microbial community structure, and microbial carbon source. For studies of soil o...

  10. Impact of external industrial sources on the regional and local air quality of Mexico Megacity

    NASA Astrophysics Data System (ADS)

    Almanza, Victor; Molina, Luisa T.; Li, Guohui; Fast, Jerome; Sosa, Gustavo

    2014-05-01

    The air quality of megacities can be influenced by external emissions sources on both regional and global scales. At the same time their outflow emissions can exert an important impact to the surrounding environment. The present study evaluates an SO2 peak observed on 24 March 2006 at the suburban supersite and ambient air quality monitoring stations located in the northern region of the Mexico City Metropolitan Area (MCMA) during MILAGRO campaign. We found that this peak could be related to an important episodic emission event coming from Tizayuca region, northeast of the MCMA. Back trajectories analyses suggest that the emission event started in the early morning at 04:00 LST and lasted for about 9 hours. The estimated emission rate is high, about 2 kg s-1. This finding suggests the possibility of 'overlooked' emission sources in Tizayuca region that could influence the air quality of the MCMA. This further motivated us to study the cement plants, including those in the State of Hidalgo and the State of Mexico. We found that they can also contribute SO2 in the NE region of the basin, at the suburban supersite and that at some monitoring stations; their contribution can be even higher than from the Tula Industrial Complex (TIC). The contribution of TIC to regional ozone levels is also estimated. The model suggests low contribution to the MCMA and slightly higher contribution at the suburban and rural supersites. However, the contribution could be high in the upper northwest region of the basin and in the southwest and south-southeast regions of the State of Hidalgo. In addition, a first estimate of the potential contribution from flaring activities to regional ozone levels is presented. Results suggest that part of the total regional ozone from TIC-generated precursors could be related to flaring activities.

  11. Dust particle charge screening in the dry-air plasma produced by an external ionization source

    SciTech Connect

    Derbenev, I. N.; Filippov, A. V.

    2015-08-15

    The ionic composition of the plasma produced by an external ionization source in dry air at atmospheric pressure and room temperature and the screening of the electric field of a dust particle in such a plasma have been investigated. The point sink model based on the diffusion-drift approximation has been used to solve the screening problem. We have established that the main species of ions in the plasma under consideration are O{sub 4}{sup +}, O{sub 2}{sup -}, and O{sub 4}{sup -} and that the dust particle potential distribution is described by a superposition of four exponentials with four different constants. We show that the first constant coincides with the inverse Debye length, the second is described by the inverse ambipolar diffusion length of the positive and negative plasma components in the characteristic time of their recombination, the third is determined by the conversion of negative ions, and the fourth is determined by the attachment and recombination of electrons and diatomic ions.

  12. Biotemplate synthesis of carbon nanostructures using bamboo as both the template and the carbon source

    SciTech Connect

    Ye, Xiaodan; Yang, Qian; Zheng, Yifan; Mo, Weimin; Hu, Jianguan; Huang, Wanzhen

    2014-03-01

    Graphical abstract: - Highlights: • A new method for the in situ growth of carbon nanostructures was demonstrated. • The bamboo was selected as both the green carbon source and the biotemplate. • Four distinct structural types of carbon nanostructure have been identified. • The corresponding growth mechanism of each carbon nanostructure was proposed. - Abstract: A series of carbon nanostructures were prepared via a biotemplate method by catalytic decomposition of bamboo impregnated with ferric nitrate. The natural nanoporous bamboo was used as both the green carbon source and the template for the in situ growth of carbon nanostructures. Scanning electron microscope, field emission transmission electron microscope and energy dispersive X-ray spectroscope were used to characterize the product. Four distinct structural types of carbon nanostructures have been identified, namely nanofibers, hollow carbon nanospheres, herringbone and bamboo-shaped nanotubes. The effect of reaction temperature (from 600 to 900 °C) on the growth behavior of carbon nanostructures was investigated and the corresponding growth mechanism was proposed. At low temperature the production of nanofibers was favored, while higher temperature led to bamboo-shaped nanostructures.

  13. A mobile light source for carbon/nitrogen cameras

    NASA Astrophysics Data System (ADS)

    Trower, W. P.; Karev, A. I.; Melekhin, V. N.; Shvedunov, V. I.; Sobenin, N. P.

    1995-05-01

    The pulsed light source for carbon/nitrogen cameras developed to image concealed narcotics/explosives is described. This race-track microtron will produce 40 mA pulses of 70 MeV electrons, have minimal size and weight, and maximal ruggedness and reliability, so that it can be transported on a truck.

  14. Carbon footprint of urban source separation for nutrient recovery.

    PubMed

    Kjerstadius, H; Bernstad Saraiva, A; Spångberg, J; Davidsson, Å

    2017-04-06

    Source separation systems for the management of domestic wastewater and food waste has been suggested as more sustainable sanitation systems for urban areas. The present study used an attributional life cycle assessment to investigate the carbon footprint and potential for nutrient recovery of two sanitation systems for a hypothetical urban area in Southern Sweden. The systems represented a typical Swedish conventional system and a possible source separation system with increased nutrient recovery. The assessment included the management chain from household collection, transport, treatment and final return of nutrients to agriculture or disposal of the residuals. The results for carbon footprint and nutrient recovery (phosphorus and nitrogen) concluded that the source separation system could increase nutrient recovery (0.30-0.38 kg P capita(-1) year(-1) and 3.10-3.28 kg N capita(-1) year(-1)), while decreasing the carbon footprint (-24 to -58 kg CO2-eq. capita(-1) year(-1)), compared to the conventional system. The nutrient recovery was increased by the use of struvite precipitation and ammonium stripping at the wastewater treatment plant. The carbon footprint decreased, mainly due to the increased biogas production, increased replacement of mineral fertilizer in agriculture and less emissions of nitrous oxide from wastewater treatment. In conclusion, the study showed that source separation systems could potentially be used to increase nutrient recovery from urban areas, while decreasing the climate impact.

  15. Chemoselective Synthesis of Carbamates using CO2 as Carbon Source.

    PubMed

    Riemer, Daniel; Hirapara, Pradipbhai; Das, Shoubhik

    2016-08-09

    Synthesis of carbamates directly from amines using CO2 as the carbon source is a straightforward and sustainable approach. Herein, we describe a highly effective and chemoselective methodology for the synthesis of carbamates at room temperature and atmospheric pressure. This methodology can also be applied to protect the amino group in amino acids and peptides, and also to synthesize important pharmaceuticals.

  16. Growth of carbon nanotube field emitters on single strand carbon fiber: a linear electron source

    NASA Astrophysics Data System (ADS)

    Kim, Ha Jin; Jong Bae, Min; Kim, Yong C.; Cho, Eun S.; Sohn, Y. C.; Kim, D. Y.; Lee, S. E.; Kang, H. S.; Han, In T.; Kim, Young H.; Patole, Shashikant P.; Yoo, Ji Beom

    2011-03-01

    The multi-stage effect has been revisited through growing carbon nanotube field emitters on single strand carbon fiber with a thickness of 11 µm. A prepared linear electron source exhibits a turn-on field as low as 0.4 V µm - 1 and an extremely high field enhancement factor of 19 300, when compared with those results from reference nanotube emitters grown on flat silicone wafer; 3.0 V µm - 1 and 2500, respectively. In addition, we introduce a novel method to grow nanotubes uniformly around the circumference of carbon fibers by using direct resistive heating on the continuously feeding carbon threads. These results open up not only a new path for synthesizing nanocomposites, but also offer an excellent linear electron source for special applications such as backlight units for liquid crystal displays and multi-array x-ray sources.

  17. Carbon and nitrogen source effects on basidiomycetes exopolysaccharide production.

    PubMed

    Elisashvili, V I; Kachlishvili, E T; Wasser, S P

    2009-01-01

    The capability to synthesize the extracellular polysaccharide (EPS) is widespread among eight mushroom species which accumulated 0.6-2.2 g/l of EPS in submerged cultivation. Glucose, maltose, and mannitol were the most appropriate carbon sources for biomass and EPS production. Organic nitrogen sources appeared to be the most suitable nitrogen sources for biomass and EPS accumulation. The cultivation process in shake flasks was successfully reproduced in a laboratory fermentor with enhanced EPS production. The highest yield of EPS (3.8-4.0 g/l) was achieved in cultivation of Agaricus nevoi and Inonotus levis.

  18. Wide area scanning system and carbon microbeams at the external microbeam facility of the INFN LABEC laboratory in Florence

    NASA Astrophysics Data System (ADS)

    Giuntini, L.; Massi, M.; Calusi, S.; Castelli, L.; Carraresi, L.; Fedi, M. E.; Gelli, N.; Liccioli, L.; Mandò, P. A.; Mazzinghi, A.; Palla, L.; Romano, F. P.; Ruberto, C.; Taccetti, F.

    2015-04-01

    Recently, developments have been made to the external scanning microbeam of INFN-LABEC laboratory in Florence. A new system for mechanical sample scanning was implemented. This system allows us to acquire large maps (up to 20 × 20 cm2), of great interest in the Cultural Heritage field. In parallel, the possibility of using carbon microbeams for experiments, such as, for example, ion beam modification of materials and MeV Secondary Ion Mass Spectrometry, has been investigated. As a test application, Particle Induced X-ray Emission with carbon microbeams has been performed on a lapis lazuli stone. First results for both wide area imaging and external carbon microbeams are briefly reported.

  19. Different carbon sources affect PCB accumulation by marine bivalves.

    PubMed

    Laitano, M V; Silva Barni, M F; Costa, P G; Cledón, M; Fillmann, G; Miglioranza, K S B; Panarello, H O

    2016-02-01

    Pampean creeks were evaluated in the present study as potential land-based sources of PCB marine contamination. Different carbon and nitrogen sources from such creeks were analysed as boosters of PCB bioaccumulation by the filter feeder bivalve Brachidontes rodriguezii and grazer limpet Siphonaria lessoni. Carbon of different source than marine and anthropogenic nitrogen assimilated by organisms were estimated through their C and N isotopic composition. PCB concentration in surface sediments and mollusc samples ranged from 2.68 to 6.46 ng g(-1) (wet weight) and from 1074 to 4583 ng g(-1) lipid, respectively, reflecting a punctual source of PCB contamination related to a landfill area. Thus, despite the low flow of creeks, they should not be underestimated as contamination vectors to the marine environment. On the other hand, mussels PCB bioaccumulation was related with the carbon source uptake which highlights the importance to consider this factor when studying PCB distribution in organisms of coastal systems.

  20. Photoautotrophic microorganisms as a carbon source for temperate soil invertebrates

    PubMed Central

    Dyckmans, Jens; Schrader, Stefan

    2016-01-01

    We tested experimentally if photoautotrophic microorganisms are a carbon source for invertebrates in temperate soils. We exposed forest or arable soils to a 13CO2-enriched atmosphere and quantified 13C assimilation by three common animal groups: earthworms (Oligochaeta), springtails (Hexapoda) and slugs (Gastropoda). Endogeic earthworms (Allolobophora chlorotica) and hemiedaphic springtails (Ceratophysella denticulata) were highly 13C enriched when incubated under light, deriving up to 3.0 and 17.0%, respectively, of their body carbon from the microbial source in 7 days. Earthworms assimilated more 13C in undisturbed soil than when the microbial material was mixed into the soil, presumably reflecting selective surface grazing. By contrast, neither adult nor newly hatched terrestrial slugs (Deroceras reticulatum) grazed on algal mats. Non-photosynthetic 13CO2 fixation in the dark was negligible. We conclude from these preliminary laboratory experiments that, in addition to litter and root-derived carbon from vascular plants, photoautotrophic soil surface microorganisms (cyanobacteria, algae) may be an ecologically important carbon input route for temperate soil animals that are traditionally assigned to the decomposer channel in soil food web models and carbon cycling studies. PMID:26740559

  1. Photoautotrophic microorganisms as a carbon source for temperate soil invertebrates.

    PubMed

    Schmidt, Olaf; Dyckmans, Jens; Schrader, Stefan

    2016-01-01

    We tested experimentally if photoautotrophic microorganisms are a carbon source for invertebrates in temperate soils. We exposed forest or arable soils to a (13)CO2-enriched atmosphere and quantified (13)C assimilation by three common animal groups: earthworms (Oligochaeta), springtails (Hexapoda) and slugs (Gastropoda). Endogeic earthworms (Allolobophora chlorotica) and hemiedaphic springtails (Ceratophysella denticulata) were highly (13)C enriched when incubated under light, deriving up to 3.0 and 17.0%, respectively, of their body carbon from the microbial source in 7 days. Earthworms assimilated more (13)C in undisturbed soil than when the microbial material was mixed into the soil, presumably reflecting selective surface grazing. By contrast, neither adult nor newly hatched terrestrial slugs (Deroceras reticulatum) grazed on algal mats. Non-photosynthetic (13)CO2 fixation in the dark was negligible. We conclude from these preliminary laboratory experiments that, in addition to litter and root-derived carbon from vascular plants, photoautotrophic soil surface microorganisms (cyanobacteria, algae) may be an ecologically important carbon input route for temperate soil animals that are traditionally assigned to the decomposer channel in soil food web models and carbon cycling studies.

  2. Warming influenced by the ratio of black carbon to sulphate and the black-carbon source

    NASA Astrophysics Data System (ADS)

    Ramana, M. V.; Ramanathan, V.; Feng, Y.; Yoon, S.-C.; Kim, S.-W.; Carmichael, G. R.; Schauer, J. J.

    2010-08-01

    Black carbon is generated by fossil-fuel combustion and biomass burning. Black-carbon aerosols absorb solar radiation, and are probably a major source of global warming. However, the extent of black-carbon-induced warming is dependent on the concentration of sulphate and organic aerosols-which reflect solar radiation and cool the surface-and the origin of the black carbon. Here we examined the impact of black-carbon-to-sulphate ratios on net warming in China, using surface and aircraft measurements of aerosol plumes from Beijing, Shanghai and the Yellow Sea. The Beijing plumes had the highest ratio of black carbon to sulphate, and exerted a strong positive influence on the net warming. Compiling all the data, we show that solar-absorption efficiency was positively correlated with the ratio of black carbon to sulphate. Furthermore, we show that fossil-fuel-dominated black-carbon plumes were approximately 100% more efficient warming agents than biomass-burning-dominated plumes. We suggest that climate-change-mitigation policies should aim at reducing fossil-fuel black-carbon emissions, together with the atmospheric ratio of black carbon to sulphate.

  3. A General Method for Calculating the External Magnetic Field from a Cylindrical Magnetic Source using Toroidal Functions

    SciTech Connect

    J Selvaggi; S Salon; O Kwon CVK Chari

    2006-02-14

    An alternative method is developed to compute the magnetic field from a circular cylindrical magnetic source. Specifically, a Fourier series expansion whose coefficients are toroidal functions is introduced which yields an alternative to the more familiar spherical harmonic solution or the Elliptic integral solution. This alternate formulation coupled with a method called charge simulation allows one to compute the external magnetic field from an arbitrary magnetic source in terms of a toroidal expansion. This expansion is valid on any finite hypothetical external observation cylinder. In other words, the magnetic scalar potential or the magnetic field intensity is computed on a exterior cylinder which encloses the magnetic source. This method can be used to accurately compute the far field where a finite element formulation is known to be inaccurate.

  4. Intensified nitrogen removal in immobilized nitrifier enhanced constructed wetlands with external carbon addition.

    PubMed

    Wang, Wei; Ding, Yi; Wang, Yuhui; Song, Xinshan; Ambrose, Richard F; Ullman, Jeffrey L

    2016-10-01

    Nitrogen removal performance response of twelve constructed wetlands (CWs) to immobilized nitrifier pellets and different influent COD/N ratios (chemical oxygen demand: total nitrogen in influent) were investigated via 7-month experiments. Nitrifier was immobilized on a carrier pellet containing 10% polyvinyl alcohol (PVA), 2.0% sodium alginate (SA) and 2.0% calcium chloride (CaCl2). A batch experiment demonstrated that 73% COD and 85% ammonia nitrogen (NH4-N) were degraded using the pellets with immobilized nitrifier cells. In addition, different carbon source supplement strategies were applied to remove the nitrate (NO3-N) transformed from NH4-N. An increase in COD/N ratio led to increasing reduction in NO3-N. Efficient nitrification and denitrification promoted total nitrogen (TN) removal in immobilized nitrifier biofortified constructed wetlands (INB-CWs). The results suggested that immobilized nitrifier pellets combined with high influent COD/N ratios could effectively improve the nitrogen removal performance in CWs.

  5. Carbon Sources for Polyhydroxyalkanoates and an Integrated Biorefinery.

    PubMed

    Jiang, Guozhan; Hill, David J; Kowalczuk, Marek; Johnston, Brian; Adamus, Grazyna; Irorere, Victor; Radecka, Iza

    2016-07-19

    Polyhydroxyalkanoates (PHAs) are a group of bioplastics that have a wide range of applications. Extensive progress has been made in our understanding of PHAs' biosynthesis, and currently, it is possible to engineer bacterial strains to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are primarily derived from food-based carbon sources, raising concerns over the sustainability of their production in terms of their impact on food prices. This paper gives an overview of the current carbon sources used for PHA production and the methods used to transform these sources into fermentable forms. This allows us to identify the opportunities and restraints linked to future sustainable PHA production. Hemicellulose hydrolysates and crude glycerol are identified as two promising carbon sources for a sustainable production of PHAs. Hemicellulose hydrolysates and crude glycerol can be produced on a large scale during various second generation biofuels' production. An integration of PHA production within a modern biorefinery is therefore proposed to produce biofuels and bioplastics simultaneously. This will create the potential to offset the production cost of biofuels and reduce the overall production cost of PHAs.

  6. Carbon Sources for Polyhydroxyalkanoates and an Integrated Biorefinery

    PubMed Central

    Jiang, Guozhan; Hill, David J.; Kowalczuk, Marek; Johnston, Brian; Adamus, Grazyna; Irorere, Victor; Radecka, Iza

    2016-01-01

    Polyhydroxyalkanoates (PHAs) are a group of bioplastics that have a wide range of applications. Extensive progress has been made in our understanding of PHAs’ biosynthesis, and currently, it is possible to engineer bacterial strains to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are primarily derived from food-based carbon sources, raising concerns over the sustainability of their production in terms of their impact on food prices. This paper gives an overview of the current carbon sources used for PHA production and the methods used to transform these sources into fermentable forms. This allows us to identify the opportunities and restraints linked to future sustainable PHA production. Hemicellulose hydrolysates and crude glycerol are identified as two promising carbon sources for a sustainable production of PHAs. Hemicellulose hydrolysates and crude glycerol can be produced on a large scale during various second generation biofuels’ production. An integration of PHA production within a modern biorefinery is therefore proposed to produce biofuels and bioplastics simultaneously. This will create the potential to offset the production cost of biofuels and reduce the overall production cost of PHAs. PMID:27447619

  7. Africa as source and sink for atmospheric carbon dioxide

    NASA Astrophysics Data System (ADS)

    Branchu, P.; Faure, H.; Ambrosi, J.-P.; van Zinderen Bakker, E. M.; Faure-Denard, L.

    1993-05-01

    Comparison of a set of paleogeographic maps of Africa for the Last Glacial Maximum (LGM) and the Holocene Climatic Optimum (HCO) allows us to discuss the contribution of paleocontinental proxy-data in paleobiomass calculations and their accuracy. Maps show considerable shifts in the area covered by the main ecosystems. In this study we have quantified these areal changes, from the LGM to the HCO, in terms of variations in carbon storage. Each biome has been assigned a carbon density in living and soil organic matter. From desert to tropical forest the mean carbon densities vary from 0 to 20 kg m -2 for phytomass and from 0 to 13 kg m -2 for soil (peat excluded). During the world deglaciation Africa was a sink for 154 Gt (standard deviation 42 Gt) of atmospheric carbon. Since the HCO Africa has been a source of carbon. More recently human deforestation is responsible for a carbon flux towards the atmosphere which is ten times the mean annual flux due to vegetation change in response to climate change. Extended to a global scale this regional test shows that the paleoenvironmental approach is more appropriate for paleobiomass estimates than calculations based only on oceanic data.

  8. Carbon Nanotubes in Water: MD Simulations of Internal and External Flow, Self Organization

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard L.; Halicioglu, Timur; Werder, Thomas; Walther, Jens; Koumoutsakos, Petros; Arnold, James (Technical Monitor)

    2001-01-01

    We have developed computational tools, based on particle codes, for molecular dynamics (MD) simulation of carbon nanotubes (CNT) in aqueous environments. The interaction of CNTs with water is envisioned as a prototype for the design of engineering nano-devices, such as artificial sterocillia and molecular biosensors. Large scale simulations involving thousands of water molecules are possible due to our efficient parallel MD code that takes long range electrostatic interactions into account. Since CNTs can be considered as rolled up sheets of graphite, we expect the CNT-water interaction to be similar to the interaction of graphite with water. However, there are fundamental differences between considering graphite and CNTs, since the curvature of CNTs affects their chemical activity and also since capillary effects play an important role for both dynamic and static behaviour of materials inside CNTs. In recent studies Gordillo and Marti described the hydrogen bond structure as well as time dependent properties of water confined in CNTs. We are presenting results from the development of force fields describing the interaction of CNTs and water based on ab-initio quantum mechanical calculations. Furthermore, our results include both water flows external to CNTs and the behaviour of water nanodroplets inside heated CNTs. In the first case (external flows) the hydrophobic behaviour of CNTs is quantified and we analyze structural properties of water in the vicinity of CNTs with diagnostics such as hydrogen bond distribution, water dipole orientation and radial distribution functions. The presence of water leads to attractive forces between CNTs as a result of their hydrophobicity. Through extensive simulations we quantify these attractive forces in terms of the number and separation of the CNT. Results of our simulations involving arrays of CNTs indicate that these exhibit a hydrophobic behaviour that leads to self-organising structures capable of trapping water clusters

  9. The Mitigation of Radio Noise from External Sources at Receiving Sites

    DTIC Science & Technology

    2007-05-01

    receiving site. Step 2—Understand sources and source mechanisms . Step 3—Locate sources. Step 4—Identify the hardware which is generating noise...Typical noise problems at a receiving site are described in Section 1. Typical sources, source mechanisms and the temporal and spectral properties...Two common types of noise will be encountered along with several less common types. These types are closely related to the source mechanisms

  10. Carbon-14 in methane sources and in atmospheric methane: The contribution from fossil carbon

    SciTech Connect

    Wahlen, M.; Tanaka, N.; Henry, R.; Deck, B.; Zeglen, J. ); Vogel, J.S.; Southon, J. ); Shemesh, A.; Fairbanks, R.; Broecker, W. )

    1989-07-21

    Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in clean air samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, peat bogs, rice fields, and tundra is somewhat, depleted in carbon-14. Atmospheric {sup 14}CH{sub 4} seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 {plus minus} 0.8% modern carbon (pMC) in the Northern Hemisphere and 120.0 {plus minus} 0.7 pMC in the Southern Hemisphere. Model calculations of source partitioning based on the carbon-14 data, CH{sub 4} concentrations, and {delta}{sup 13}C in CH{sub 4} indicate that 21 {plus minus} 3% of atmospheric CH{sub 4} was derived from fossil carbon at the end of 1987. The data also indicate that pressurized water reactors are an increasingly important source of {sup 14}CH{sub 4}. 38 refs., 3 figs., 2 tabs.

  11. Bioavailability of PAHs: effects of soot carbon and PAH source.

    PubMed

    Thorsen, Waverly A; Cope, W Gregory; Shea, Damian

    2004-04-01

    The bioavailability of 38 individual polycyclic aromatic hydrocarbon (PAH) compounds was determined through calculation of biota-sediment-accumulation factors (BSAF). BSAF values were calculated from individual PAH concentrations in freshwater mussel, marine clam, and sediment obtained from field and laboratory bioaccumulation studies. Sediment that was amended with different types of soot carbon (SC) was used in some of the bioaccumulation experiments. BSAF values for petrogenic PAH were greater than those for pyrogenic PAH (e.g., 1.57 +/- 0.53 vs 0.25 +/- 0.23, respectively), indicating that petrogenic PAH are more bioavailable than pyrogenic PAH (p < 0.05). This trend was consistent among marine and freshwater sites. Increased SC content of sediment resulted in a linear decrease in the bioavailability of pyrogenic PAHs (r2 = 0.85). The effect of increasing SC content on petrogenic PAH was negligible. SC was considered as an additional sorptive phase when calculating BSAF values, and using PAH-SC partition coefficients from the literature, we obtained unreasonably large BSAF values for all petrogenic PAH and some pyrogenic PAH. This led us to conclude that a quantitative model to assess bioavailability through a combination of organic carbon and soot carbon sorption is not applicable among field sites with a wide range of soot carbon fractions and PAH sources, at least given our current knowledge of PAH-SC partitioning. Our data offer evidence that many factors including analysis of a full suite of PAH analytes, PAH hydrophobicity, sediment organic carbon content, sediment soot carbon content, and PAH source are importantto adequately assess PAH bioavailability in the environment.

  12. Methane and carbon at equilibrium in source rocks.

    PubMed

    Mango, Frank D

    2013-12-12

    Methane in source rocks may not exist exclusively as free gas. It could exist in equilibrium with carbon and higher hydrocarbons: CH4 + C < = > Hydrocarbon. Three lines of evidence support this possibility. 1) Shales ingest gas in amounts and selectivities consistent with gas-carbon equilibrium. There is a 50% increase in solid hydrocarbon mass when Fayetteville Shale is exposed to methane (450 psi) under moderate conditions (100°C): Rock-Eval S2 (mg g-1) 8.5 = > 12.5. All light hydrocarbons are ingested, but with high selectivity, consistent with competitive addition to receptor sites in a growing polymer. Mowry Shale ingests butane vigorously from argon, for example, but not from methane under the same conditions. 2) Production data for a well producing from Fayetteville Shale declines along the theoretical curve for withdrawing gas from higher hydrocarbons in equilibrium with carbon. 3) A new general gas-solid equilibrium model accounts for natural gas at thermodynamic equilibrium, and C6-C7 hydrocarbons constrained to invariant compositions. The results make a strong case for methane in equilibrium with carbon and higher hydrocarbons. If correct, the higher hydrocarbons in source rocks are gas reservoirs, raising the possibility of substantially more gas in shales than analytically apparent, and far more gas in shale deposits than currently recognized.

  13. Methane and carbon at equilibrium in source rocks

    PubMed Central

    2013-01-01

    Methane in source rocks may not exist exclusively as free gas. It could exist in equilibrium with carbon and higher hydrocarbons: CH4 + C < = > Hydrocarbon. Three lines of evidence support this possibility. 1) Shales ingest gas in amounts and selectivities consistent with gas-carbon equilibrium. There is a 50% increase in solid hydrocarbon mass when Fayetteville Shale is exposed to methane (450 psi) under moderate conditions (100°C): Rock-Eval S2 (mg g-1) 8.5 = > 12.5. All light hydrocarbons are ingested, but with high selectivity, consistent with competitive addition to receptor sites in a growing polymer. Mowry Shale ingests butane vigorously from argon, for example, but not from methane under the same conditions. 2) Production data for a well producing from Fayetteville Shale declines along the theoretical curve for withdrawing gas from higher hydrocarbons in equilibrium with carbon. 3) A new general gas-solid equilibrium model accounts for natural gas at thermodynamic equilibrium, and C6-C7 hydrocarbons constrained to invariant compositions. The results make a strong case for methane in equilibrium with carbon and higher hydrocarbons. If correct, the higher hydrocarbons in source rocks are gas reservoirs, raising the possibility of substantially more gas in shales than analytically apparent, and far more gas in shale deposits than currently recognized. PMID:24330266

  14. Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

    SciTech Connect

    Wang, Hao; Wang, Yun; Dai, Xiao; Zou, Guifu E-mail: zouguifu@suda.edu.cn; Gao, Peng; Zhang, Ke-Qin E-mail: zouguifu@suda.edu.cn; Du, Dezhuang; Guo, Jun

    2015-08-01

    In this study, fluorescent nitrogen-doped carbon dots (NCDs) were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility.

  15. Inorganic Carbon Accumulation and Photosynthesis in a Blue-green Alga as a Function of External pH 1

    PubMed Central

    Coleman, John R.; Colman, Brian

    1981-01-01

    The blue-green alga Coccochloris peniocystis photosynthesizes optimally over the pH range of 7.0 to 10.0, but the O2-evolution rate is inhibited below pH 7.0 and ceases below pH 5.25. Measurement of the inorganic carbon pool in this alga in the light, using the silicone-fluid filtration technique demonstrated that the rate of accumulation of dissolved inorganic carbon remained relatively constant over a wide pH range. At external dissolved inorganic carbon concentrations of 0.56 to 0.89 millimolar the internal concentration after 30 seconds illumination was greater than 3.5 millimolar over the entire pH range. Intracellular pH measured in the light using [14C]5,5-dimethyloxazolidine-2,4-dione and [14C]methylamine dropped from pH 7.6 at an external pH of 7.0 to pH 6.6 at an external pH of 5.25. Above an external pH of 7.0 the intracellular pH rose gradually to pH 7.9 at an external pH 10.0. Ribulose-1,5-bisphosphate carboxylase activity of cell-free algal extracts exhibited optimal activity at pH 7.5 to 7.8 but was inactive below pH 6.5. It is suggested that the inability of Coccochloris to maintain its intracellular pH when in an acidic environment restricts its photosynthetic capacity by a direct pH effect on the principal CO2 fixing enzyme. PMID:16661792

  16. Critical review of black carbon and elemental carbon source apportionment in Europe and the United States

    NASA Astrophysics Data System (ADS)

    Briggs, Nicole L.; Long, Christopher M.

    2016-11-01

    An increasing number of air pollution source apportionment studies in Europe and the United States have focused on the black carbon (BC) fraction of ambient particulate matter (PM) given its linkage with adverse public health and climate impacts. We conducted a critical review of European and US BC source apportionment studies published since 2003. Since elemental carbon (EC) has been used as a surrogate measure of BC, we also considered source apportionment studies of EC measurements. This review extends the knowledge presented in previous ambient PM source apportionment reviews because we focus on BC and EC and critically examine the differences between source apportionment results for different methods and source categories. We identified about 50 BC and EC source apportionment studies that have been conducted in either Europe or the US since 2003, finding a striking difference in the commonly used source apportionment methods between the two regions and variations in the assigned source categories. Using three dominant methodologies (radiocarbon, aethalometer, and macro-tracer methods) that only allow for BC to be broadly apportioned into either fossil fuel combustion or biomass burning source categories, European studies generally support fossil fuel combustion as the dominant ambient BC source, but also show significant biomass burning contributions, in particular in wintertime at non-urban locations. Among US studies where prevailing methods such as chemical mass balance (CMB) and positive matrix factorization (PMF) models have allowed for estimation of more refined source contributions, there are fewer findings showing the significance of biomass burning and variable findings on the relative proportion of BC attributed to diesel versus gasoline emissions. Overall, the available BC source apportionment studies provide useful information demonstrating the significance of both fossil fuel combustion and biomass burning BC emission sources in Europe and the US

  17. Secure optionally passive RFID tag or sensor with external power source and data logging

    DOEpatents

    Nekoogar, Faranak; Reynolds, Matthew; Lefton, Scott; Dowla, Farid; Twogood, Richard

    2016-05-31

    A secure optionally passive RFID tag or sensor system comprises a passive RFID tag having means for receiving radio signals from at least one base station and for transmitting radio signals to at least one base station, where the tag is capable of being powered exclusively by received radio energy, and an external power and data logging device having at least one battery and electronic circuitry including a digital memory configured for storing and recalling data. The external power and data logging device has a means for powering the tag, and also has a means.

  18. Carbon and black carbon in Yosemite National Park soils: sources, prescribed fire impacts, and policies

    NASA Astrophysics Data System (ADS)

    Shrestha, G.; Traina, S. J.

    2012-12-01

    We investigated the chemical and radiocarbon properties of black carbon recently deposited and accumulated in surface soils of six sites along an altitudinal gradient in Yosemite National Park, central California. The effect of prescribed (or controlled) forest burning on existing carbon and black carbon in surface soils was assessed to illuminate the role of this forest management and wildfire control strategy in the soil carbon cycle. The proportional contribution of fossil fuel or radiocarbon dead carbon versus biomass sources on these black carbon materials was analyzed to elucidate their origin, estimate their ages and explore the possible effects of prescribed burning on the amount of black carbon produced recently as well as historically. Supplementing these field results, we conducted a comparative spatial analysis of recent prescribed burn and wildfire coverage in Central California's San Joaquin Valley to approximate the effectiveness of prescribed burning for wildfire prevention. Federal and California policies pertaining to prescribed forest fires and/or black carbon were then evaluated for their effectiveness, air quality considerations, and environmental benefits. 13C NMR spectrum of soil surface char from study sites Prescribed burn coverage versus wildfires in central California

  19. Role of metabolite transporters in source-sink carbon allocation

    PubMed Central

    Ludewig, Frank; Flügge, Ulf-Ingo

    2013-01-01

    Plants assimilate carbon dioxide during photosynthesis in chloroplasts. Assimilated carbon is subsequently allocated throughout the plant. Generally, two types of organs can be distinguished, mature green source leaves as net photoassimilate exporters, and net importers, the sinks, e.g., roots, flowers, small leaves, and storage organs like tubers. Within these organs, different tissue types developed according to their respective function, and cells of either tissue type are highly compartmentalized. Photoassimilates are allocated to distinct compartments of these tissues in all organs, requiring a set of metabolite transporters mediating this intercompartmental transfer. The general route of photoassimilates can be briefly described as follows. Upon fixation of carbon dioxide in chloroplasts of mesophyll cells, triose phosphates either enter the cytosol for mainly sucrose formation or remain in the stroma to form transiently stored starch which is degraded during the night and enters the cytosol as maltose or glucose to be further metabolized to sucrose. In both cases, sucrose enters the phloem for long distance transport or is transiently stored in the vacuole, or can be degraded to hexoses which also can be stored in the vacuole. In the majority of plant species, sucrose is actively loaded into the phloem via the apoplast. Following long distance transport, it is released into sink organs, where it enters cells as source of carbon and energy. In storage organs, sucrose can be stored, or carbon derived from sucrose can be stored as starch in plastids, or as oil in oil bodies, or – in combination with nitrogen – as protein in protein storage vacuoles and protein bodies. Here, we focus on transport proteins known for either of these steps, and discuss the implications for yield increase in plants upon genetic engineering of respective transporters. PMID:23847636

  20. Trace Metal Source Terms in Carbon Sequestration Environments

    SciTech Connect

    Karamalidis, Athanasios; Torres, Sharon G.; Hakala, Jacqueline A.; Shao, Hongbo; Cantrell, Kirk J.; Carroll, Susan A.

    2013-01-01

    ABSTRACT: Carbon dioxide sequestration in deep saline and depleted oil geologic formations is feasible and promising; however, possible CO2 or CO2-saturated brine leakage to overlying aquifers may pose environmental and health impacts. The purpose of this study was to experimentally define to provide a range of concentrations that can be used as the trace element source term for reservoirs and leakage pathways in risk simulations. Storage source terms for trace metals are needed to evaluate the impact of brines leaking into overlying drinking water aquifers. The trace metal release was measured from cements and sandstones, shales, carbonates, evaporites, and basalts from the Frio, In Salah, Illinois Basin, Decatur, Lower Tuscaloosa, Weyburn-Midale, Bass Islands, and Grand Ronde carbon sequestration geologic formations. Trace metal dissolution was tracked by measuring solution concentrations over time under conditions (e.g., pressures, temperatures, and initial brine compositions) specific to the sequestration projects. Existing metrics for maximum contaminant levels (MCLs) for drinking water as defined by the U.S. Environmental Protection Agency (U.S. EPA) were used to categorize the relative significance of metal concentration changes in storage environments because of the presence of CO2. Results indicate that Cr and Pb released from sandstone reservoir and shale cap rocks exceed the MCLs byan order of magnitude, while Cd and Cu were at or below drinking water thresholds. In carbonate reservoirs As exceeds the MCLs by an order of magnitude, while Cd, Cu, and Pb were at or below drinking water standards. Results from this study can be used as a reasonable estimate of the trace element source term for reservoirs and leakage pathways in risk simulations to further evaluate the impact of leakage on groundwater quality.

  1. Trace Metal Source Terms in Carbon Sequestration Environments

    SciTech Connect

    Karamalidis, Athanasios K; Torres, Sharon G; Hakala, J Alexandra; Shao, Hongbo; Cantrell, Kirk J; Carroll, Susan

    2012-02-05

    Carbon dioxide sequestration in deep saline and depleted oil geologic formations is feasible and promising, however, possible CO₂ or CO₂-saturated brine leakage to overlying aquifers may pose environmental and health impacts. The purpose of this study was to experimentally define trace metal source terms from the reaction of supercritical CO₂, storage reservoir brines, reservoir and cap rocks. Storage reservoir source terms for trace metals are needed to evaluate the impact of brines leaking into overlying drinking water aquifers. The trace metal release was measured from sandstones, shales, carbonates, evaporites, basalts and cements from the Frio, In Salah, Illinois Basin – Decatur, Lower Tuscaloosa, Weyburn-Midale, Bass Islands and Grand Ronde carbon sequestration geologic formations. Trace metal dissolution is tracked by measuring solution concentrations over time under conditions (e.g. pressures, temperatures, and initial brine compositions) specific to the sequestration projects. Existing metrics for Maximum Contaminant Levels (MCLs) for drinking water as defined by the U.S. Environmental Protection Agency (U.S. EPA) were used to categorize the relative significance of metal concentration changes in storage environments due to the presence of CO₂. Results indicate that Cr and Pb released from sandstone reservoir and shale cap rock exceed the MCLs by an order of magnitude while Cd and Cu were at or below drinking water thresholds. In carbonate reservoirs As exceeds the MCLs by an order of magnitude, while Cd, Cu, and Pb were at or below drinking water standards. Results from this study can be used as a reasonable estimate of the reservoir and caprock source term to further evaluate the impact of leakage on groundwater quality.

  2. Trace metal source terms in carbon sequestration environments.

    PubMed

    Karamalidis, Athanasios K; Torres, Sharon G; Hakala, J Alexandra; Shao, Hongbo; Cantrell, Kirk J; Carroll, Susan

    2013-01-02

    Carbon dioxide sequestration in deep saline and depleted oil geologic formations is feasible and promising; however, possible CO(2) or CO(2)-saturated brine leakage to overlying aquifers may pose environmental and health impacts. The purpose of this study was to experimentally define a range of concentrations that can be used as the trace element source term for reservoirs and leakage pathways in risk simulations. Storage source terms for trace metals are needed to evaluate the impact of brines leaking into overlying drinking water aquifers. The trace metal release was measured from cements and sandstones, shales, carbonates, evaporites, and basalts from the Frio, In Salah, Illinois Basin, Decatur, Lower Tuscaloosa, Weyburn-Midale, Bass Islands, and Grand Ronde carbon sequestration geologic formations. Trace metal dissolution was tracked by measuring solution concentrations over time under conditions (e.g., pressures, temperatures, and initial brine compositions) specific to the sequestration projects. Existing metrics for maximum contaminant levels (MCLs) for drinking water as defined by the U.S. Environmental Protection Agency (U.S. EPA) were used to categorize the relative significance of metal concentration changes in storage environments because of the presence of CO(2). Results indicate that Cr and Pb released from sandstone reservoir and shale cap rocks exceed the MCLs by an order of magnitude, while Cd and Cu were at or below drinking water thresholds. In carbonate reservoirs As exceeds the MCLs by an order of magnitude, while Cd, Cu, and Pb were at or below drinking water standards. Results from this study can be used as a reasonable estimate of the trace element source term for reservoirs and leakage pathways in risk simulations to further evaluate the impact of leakage on groundwater quality.

  3. Constrained Maximum Likelihood Estimation for Model Calibration Using Summary-level Information from External Big Data Sources.

    PubMed

    Chatterjee, Nilanjan; Chen, Yi-Hau; Maas, Paige; Carroll, Raymond J

    2016-03-01

    Information from various public and private data sources of extremely large sample sizes are now increasingly available for research purposes. Statistical methods are needed for utilizing information from such big data sources while analyzing data from individual studies that may collect more detailed information required for addressing specific hypotheses of interest. In this article, we consider the problem of building regression models based on individual-level data from an "internal" study while utilizing summary-level information, such as information on parameters for reduced models, from an "external" big data source. We identify a set of very general constraints that link internal and external models. These constraints are used to develop a framework for semiparametric maximum likelihood inference that allows the distribution of covariates to be estimated using either the internal sample or an external reference sample. We develop extensions for handling complex stratified sampling designs, such as case-control sampling, for the internal study. Asymptotic theory and variance estimators are developed for each case. We use simulation studies and a real data application to assess the performance of the proposed methods in contrast to the generalized regression (GR) calibration methodology that is popular in the sample survey literature.

  4. Optical Performance of Carbon-Nanotube Electron Sources

    SciTech Connect

    Jonge, Niels de; Allioux, Myriam; Oostveen, Jim T.; Teo, Kenneth B. K.; Milne, William I.

    2005-05-13

    The figure of merit for the electron optical performance of carbon-nanotube (CNT) electron sources is presented. This figure is given by the relation between the reduced brightness and the energy spread in the region of stable emission. It is shown experimentally that a CNT electron source exhibits a highly stable emission process that follows the Fowler-Nordheim theory for field emission, fixing the relationship among the energy spread, the current, and the radius. The performance of the CNT emitter under realistic operating conditions is compared with state-of-the-art electron point sources. It is demonstrated that the reduced brightness is a function of the tunneling parameter, a measure of the energy spread at low temperatures, only, independent of the geometry of the emitter.

  5. Sources and sinks of carbon dioxide in the Arctic regions

    SciTech Connect

    Gosink, T. A.; Kelley, J. J.

    1982-01-01

    The data base required to adequately ascertain seasonal source and sink strengths in the arctic regions is difficult to obtain. However, there are now a reasonable quantity of data for this polar region to estimate sources and sinks within the Arctic which may contribute significantly to the annual tropospheric CO/sub 2/ concentration fluctuation. The sea-ice-air and the sea-air interfaces account for most of the contribution to the sources and sinks for carbon dioxide. Although the arctic and subarctic region is small in extent, it certainly is not impervious and ice sealed. Our estimate, based on historical data and current research, indicates that the Arctic, which is about 4% of the earth's surface, is an annual net sink for approx. 10/sup 15/ g CO/sub 2/ accounting for an equivalent of approx. 3% of the annual anthropogenic contribution of CO/sub 2/ to the troposphere.

  6. Utilization of carbon sources in a northern Brazilian mangrove ecosystem

    NASA Astrophysics Data System (ADS)

    Giarrizzo, Tommaso; Schwamborn, Ralf; Saint-Paul, Ulrich

    2011-12-01

    Carbon and nitrogen stable isotope ratios ( 13C and 15N) and trophic level (TL) estimates based on stomach content analysis and published data were used to assess the contribution of autotrophic sources to 55 consumers in an intertidal mangrove creek of the Curuçá estuary, northern Brazil. Primary producers showed δ 13C signatures ranging between -29.2 and -19.5‰ and δ 15N from 3.0 to 6.3‰. The wide range of the isotopic composition of carbon of consumers (-28.6 to -17.1‰) indicated that different autotrophic sources are important in the intertidal mangrove food webs. Food web segregation structures the ecosystem into three relatively distinct food webs: (i) mangrove food web, where vascular plants contribute directly or indirectly via POM to the most 13C-depleted consumers (e.g. Ucides cordatus and zooplanktivorous food chains); (ii) algal food web, where benthic algae are eaten directly by consumers (e.g. Uca maracoani, mullets, polychaetes, several fishes); (iii) mixed food web where the consumers use the carbon from different primary sources (mainly benthivorous fishes). An IsoError mixing model was used to determine the contributions of primary sources to consumers, based on δ 13C values. Model outputs were very sensitive to the magnitude of trophic isotope fractionation and to the variability in 13C data. Nevertheless, the simplification of the system by a priori aggregation of primary producers allowed interpretable results for several taxa, revealing the segregation into different food webs.

  7. Effects of Carbon Source, Carbon Concentration, and Chlorination on Growth Related Parameters of Heterotrophic Biofilm Bacteria.

    PubMed

    Ellis; Butterfield; Jones; McFeters; Camper

    1999-11-01

    To investigate growth of heterotrophic biofilm bacteria, a model biofilm reactor was developed to simulate a drinking water distribution system. Controlled addition of three different carbon sources (amino acids, carbohydrates, and humics) at three different concentrations (500, 1,000, and 2,000 ppb carbon) in the presence and absence of chlorine were used in separate experiments. An additional experiment was run with a 1:1:2 mixture of the above carbon sources. Biofilm and effluent total and culturable cells in addition to total and dissolved organic carbon were measured in order to estimate specific growth rates (SGRs), observed yields, population densities, and bacterial carbon production rates. Bacterial carbon production rates (µg C/L day) were extremely high in the control biofilm communities (range = 295-1,738). Both growth rate and yield decreased with increasing carbon concentrations. Therefore, biofilm growth rates were zero-order with respect to the carbon concentrations used in these experiments. There was no correlation between growth rate and carbon concentration, but there was a significant negative correlation between growth rate and biofilm cell density (r = -0.637, p = 0.001 control and r = -0.57, p = 0.021 chlorinated biofilms). Growth efficiency was highest at the lowest carbon concentration (range = 12-4.5%, amino acids and humics respectively). Doubling times ranged from 2.3-15.4 days in the control biofilms and 1-12.3 days in the chlorinated biofilms. Growth rates were significantly higher in the presence of chlorine for the carbohydrates, humics, and mixed carbon sources (p = 0.004, < 0.0005, 0.013, respectively). The concept of r/K selection theory was used to explain the results with respect to specific growth rates and yields. Humic removal by the biofilm bacteria (78% and 56% for the control and chlorinated biofilms, respectively) was higher than previously reported literature values for planktonic bacteria. A number of control

  8. Siberian Arctic black carbon sources constrained by model and observation

    NASA Astrophysics Data System (ADS)

    Winiger, Patrik; Andersson, August; Eckhardt, Sabine; Stohl, Andreas; Semiletov, Igor P.; Dudarev, Oleg V.; Charkin, Alexander; Shakhova, Natalia; Klimont, Zbigniew; Heyes, Chris; Gustafsson, Örjan

    2017-02-01

    Black carbon (BC) in haze and deposited on snow and ice can have strong effects on the radiative balance of the Arctic. There is a geographic bias in Arctic BC studies toward the Atlantic sector, with lack of observational constraints for the extensive Russian Siberian Arctic, spanning nearly half of the circum-Arctic. Here, 2 y of observations at Tiksi (East Siberian Arctic) establish a strong seasonality in both BC concentrations (8 ngṡm‑3 to 302 ngṡm‑3) and dual-isotope–constrained sources (19 to 73% contribution from biomass burning). Comparisons between observations and a dispersion model, coupled to an anthropogenic emissions inventory and a fire emissions inventory, give mixed results. In the European Arctic, this model has proven to simulate BC concentrations and source contributions well. However, the model is less successful in reproducing BC concentrations and sources for the Russian Arctic. Using a Bayesian approach, we show that, in contrast to earlier studies, contributions from gas flaring (6%), power plants (9%), and open fires (12%) are relatively small, with the major sources instead being domestic (35%) and transport (38%). The observation-based evaluation of reported emissions identifies errors in spatial allocation of BC sources in the inventory and highlights the importance of improving emission distribution and source attribution, to develop reliable mitigation strategies for efficient reduction of BC impact on the Russian Arctic, one of the fastest-warming regions on Earth.

  9. Siberian Arctic black carbon sources constrained by model and observation.

    PubMed

    Winiger, Patrik; Andersson, August; Eckhardt, Sabine; Stohl, Andreas; Semiletov, Igor P; Dudarev, Oleg V; Charkin, Alexander; Shakhova, Natalia; Klimont, Zbigniew; Heyes, Chris; Gustafsson, Örjan

    2017-02-14

    Black carbon (BC) in haze and deposited on snow and ice can have strong effects on the radiative balance of the Arctic. There is a geographic bias in Arctic BC studies toward the Atlantic sector, with lack of observational constraints for the extensive Russian Siberian Arctic, spanning nearly half of the circum-Arctic. Here, 2 y of observations at Tiksi (East Siberian Arctic) establish a strong seasonality in both BC concentrations (8 ng⋅m(-3) to 302 ng⋅m(-3)) and dual-isotope-constrained sources (19 to 73% contribution from biomass burning). Comparisons between observations and a dispersion model, coupled to an anthropogenic emissions inventory and a fire emissions inventory, give mixed results. In the European Arctic, this model has proven to simulate BC concentrations and source contributions well. However, the model is less successful in reproducing BC concentrations and sources for the Russian Arctic. Using a Bayesian approach, we show that, in contrast to earlier studies, contributions from gas flaring (6%), power plants (9%), and open fires (12%) are relatively small, with the major sources instead being domestic (35%) and transport (38%). The observation-based evaluation of reported emissions identifies errors in spatial allocation of BC sources in the inventory and highlights the importance of improving emission distribution and source attribution, to develop reliable mitigation strategies for efficient reduction of BC impact on the Russian Arctic, one of the fastest-warming regions on Earth.

  10. Agenda and Meeting Summary from Best Practices Training on Arctic Black Carbon: Reduction of Black Carbon from Diesel Sources

    EPA Pesticide Factsheets

    From April 15-19, 2013, EPA's partners hosted the Best Practices Training on Arctic Black Carbon: Reduction of Black Carbon from Diesel Sources in Murmansk, Russia. Over the course of this event, participants:

  11. Agenda and Meeting Summary from Final Workshop on Arctic Black Carbon: Reduction of Black Carbon from Diesel Sources

    EPA Pesticide Factsheets

    The U.S. Environmental Protection Agency, Battelle Memorial Institute and WWF-Russia organized the final workshop on Arctic Black Carbon: Reduction of Black Carbon from Diesel Sources on November 5, 2014 in Murmansk, Russia.

  12. Combined energy-power action on a source in the constant Mach number regime with the given external force

    NASA Astrophysics Data System (ADS)

    Kucherov, A. N.

    2017-02-01

    Combined action on a source that flows into a submerged area or vacuum in the constant Mach number regime has been studied. The action by an external force has been defined with a constant distribution function (the force is given per unit volume) and with a distribution function proportional to the gas density (the force is given per unit mass). The investigations have been carried out for cylindrical and spherical sources. Similarity and differences, advantages and drawbacks of the above-mentioned cases and variants have been analyzed. It has been shown that the enthalpy increases significantly in subsonic flow (for the Mach number smaller than unity) by several times in the cylindrical source and by more than an order of magnitude in the spherical source. The total enthalpy increment increases with the length of the action zone or with the coordinate of the closing section.

  13. Russia's black carbon emissions: focus on diesel sources

    NASA Astrophysics Data System (ADS)

    Kholod, Nazar; Evans, Meredydd; Kuklinski, Teresa

    2016-09-01

    Black carbon (BC) is a significant climate forcer with a particularly pronounced forcing effect in polar regions such as the Russian Arctic. Diesel combustion is a major global source of BC emissions, accounting for 25-30 % of all BC emissions. While the demand for diesel is growing in Russia, the country's diesel emissions are poorly understood. This paper presents a detailed inventory of Russian BC emissions from diesel sources. Drawing on a complete Russian vehicle registry with detailed information about vehicle types and emission standards, this paper analyzes BC emissions from diesel on-road vehicles. We use the COPERT emission model (COmputer Programme to calculate Emissions from Road Transport) with Russia-specific emission factors for all types of on-road vehicles. On-road diesel vehicles emitted 21 Gg of BC in 2014: heavy-duty trucks account for 60 % of the on-road BC emissions, while cars represent only 5 % (light commercial vehicles and buses account for the remainder). Using Russian activity data and fuel-based emission factors, the paper also presents BC emissions from diesel locomotives and ships, off-road engines in industry, construction and agriculture, and generators. The study also factors in the role of superemitters in BC emissions from diesel on-road vehicles and off-road sources. The total emissions from diesel sources in Russia are estimated to be 49 Gg of BC and 17 Gg of organic carbon (OC) in 2014. Off-road diesel sources emitted 58 % of all diesel BC in Russia.

  14. Russia's black carbon emissions: focus on diesel sources

    SciTech Connect

    Kholod, Nazar; Evans, Meredydd; Kuklinski, Teresa

    2016-01-01

    Black carbon (BC) is a significant climate forcer with a particularly pronounced forcing effect in polar regions such as the Russian Arctic. Diesel combustion is a major global source of BC emissions, accounting for 25–30% of all BC emissions. While the demand for diesel is growing in Russia, the country's diesel emissions are poorly understood. This paper presents a detailed inventory of Russian BC emissions from diesel sources. Drawing on a complete Russian vehicle registry with detailed information about vehicle types and emission standards, this paper analyzes BC emissions from diesel on-road vehicles. We use the COPERT emission model (COmputer Programme to calculate Emissions from Road Transport) with Russia-specific emission factors for all types of on-road vehicles. On-road diesel vehicles emitted 21 Gg of BC in 2014: heavy-duty trucks account for 60% of the on-road BC emissions, while cars represent only 5% (light commercial vehicles and buses account for the remainder). Using Russian activity data and fuel-based emission factors, the paper also presents BC emissions from diesel locomotives and ships, off-road engines in industry, construction and agriculture, and generators. The study also factors in the role of superemitters in BC emissions from diesel on-road vehicles and off-road sources. The total emissions from diesel sources in Russia are estimated to be 49 Gg of BC and 17 Gg of organic carbon (OC) in 2014. Off-road diesel sources emitted 58% of all diesel BC in Russia.

  15. Kupier prize lecture: Sources of solar-system carbon

    NASA Technical Reports Server (NTRS)

    Anders, Edward; Zinner, Ernst

    1994-01-01

    We have tried to deconvolve Solar-System carbon into its sources, on the basis of C-12/C-13 ratios (equivalent to R). Interstellar SiC in meteorites, representing greater than 4.6-Ga-old stardust from carbon stars, is isotopically heavier (bar R = 38 +/- 2) than Solar-System carbon (89), implying that the latter contains an additional, light component. A likely source are massive stars, mainly Type II supernovae and Wolf-Rayet stars, which, being O-rich, eject their C largely as CO rather than carbonaceous dust. The fraction of such light C in the Solar System depends on R(sub light) in the source. For R(sub light) = 180-1025 (as in 'Group 4' meteoritic graphite spherules, which apparently came from massive stars greater than 4.6 Ga ago), the fraction of light C is 0.79-0.61. Similar results are obtained for present-day data on red giants and interstellar gas. Although both have become enriched in C-13 due to galactic evolution (to bar-R = 20 and 57), the fraction of the light component in interstellar gas again is near 0.7. (Here bar R represents the mean of a mixture calculated via atom fractions; it is not identical to the arithmetic mean R). Interstellar graphite, unlike SiC, shows a large peak at R approximately equal 90, near the solar value. Although some of the grains may be of local origin, others show anomalies in other elements and hence are exotic. Microdiamonds, with R = 93, also are exotic on the basis of their Xe and N. Apparently R approximately 90 was a fairly common composition 4.6 Ga ago, of stars as well as the ISM.

  16. When Forest become carbon sources: Impact of herbivory on carbon balance

    NASA Astrophysics Data System (ADS)

    Schafer, K. V.; Clark, K. L.; Skowronski, N. S.

    2008-12-01

    Traditionally forests are thought to be carbon sinks and are becoming important trading commodities in the carbon trading markets. However, disturbances such as fire, hurricanes and herbivory can lead to forests being sources rather than sinks of carbon. Here, we investigate the carbon balance of an oak/pine forest in the New Jersey Pine Barrens under herbivory attack in summer 2007. Net primary productivity (NPP) was reduced to ca 70% of previous year NPP (535 g m-2 a-1 in 2006) and canopy net assimilation (AnC), as modeled with the Canopy Conductance Constrained Carbon Assimilation model (4C-A), was reduced to ca 65 % of previous year (1335 g m-2 a-1 in 2006) AnC or ca 1015 g C m-2 a-1. Although the trees were defoliated for only 15 % of the normal annual growing season, the impact amounted to ca 30 % of C accumulation loss when integrated over the year. Overall NPP in 2007 was ca 378 g C m-2 a-1 with 50 % of NPP being allocated to foliage production which constitutes a short term carbon pool. On an ecosystem level net ecosystem exchange amounted to a release of 293 g C m-2 a-1 thus becoming a carbon source over the course of the year rather than being a sink for C. The overall impact of the defoliation spanned 21% of upland forests (320 km2) in the New Jersey Pine Barrens thus representing a significant amount of overall C being emitted back to the atmosphere rather than being accumulated in the biosphere.

  17. Enhanced biomass production through optimization of carbon source and utilization of wastewater as a nutrient source.

    PubMed

    Gupta, Prabuddha L; Choi, Hee-Jeong; Pawar, Radheshyam R; Jung, Sokhee P; Lee, Seung-Mok

    2016-12-15

    The study aimed to utilize the domestic wastewater as nutrient feedstock for mixotrophic cultivation of microalgae by evaluating appropriate carbon source. The microalgae Chlorella vulgaris was cultivated in municipal wastewater under various carbon sources (glucose, glycerol, and acetate), followed by optimization of appropriate carbon source concentration to augment the biomass, lipid, and carbohydrate contents. Under optimized conditions, namely of 5 g/L glucose, C. vulgaris showed higher increments of biomass with 1.39 g/L dry cell weight achieving biomass productivity of 0.13 g/L/d. The biomass accumulated 19.29 ± 1.83% total lipid, 41.4 ± 1.46% carbohydrate, and 33.06 ± 1.87% proteins. Moreover, the cultivation of Chlorella sp. in glucose-supplemented wastewater removed 96.9% chemical oxygen demand, 65.3% total nitrogen, and 71.2% total phosphate. The fatty acid methyl ester obtained showed higher amount (61.94%) of saturated fatty acid methyl esters associated with the improved fuel properties. These results suggest that mixotrophic cultivation using glucose offers great potential in the production of renewable biomass, wastewater treatment, and consequent production of high-value microalgal oil.

  18. Regional prediction of carbon isotopes in soil carbonates for Asian dust source tracer

    NASA Astrophysics Data System (ADS)

    Chen, Bing; Cui, Xinjuan; Wang, Yaqiang

    2016-10-01

    Dust particles emitted from deserts and semi-arid lands in northern China cause particulate pollution that increases the burden of disease particularly for urban population in East Asia. The stable carbon isotopes (δ13C) of carbonates in soils and dust aerosols in northern China were investigated. We found that the δ13C of carbonates in surface soils in northern China showed clearly the negative correlation (R2 = 0.73) with Normalized Difference Vegetation Index (NDVI). Using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-derived NDVI, we predicted the regional distribution of δ13C of soil carbonates in deserts, sandy lands, and steppe areas. The predictions show the mean δ13C of -0.4 ± 0.7‰ in soil carbonates in Taklimakan Desert and Gobi Deserts, and the isotope values decrease to -3.3 ± 1.1‰ in sandy lands. The increase in vegetation coverage depletes 13C in soil carbonates, thus the steppe areas are predicted by the lowest δ13C levels (-8.1 ± 1.7‰). The measurements of atmospheric dust samples at eight sites showed that the Asian dust sources were well assigned by the 13C mapping in surface soils. Predicting 13C in large geographical areas with fine resolution offers a cost-effective tracer to monitor dust emissions from sandy lands and steppe areas which show an increasing role in Asian dust loading driven by climate change and human activities.

  19. The influence of external transverse magnetic field in propagation of electrostatic oscillations in single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Abdikian, Alireza

    2016-10-01

    Propagation of an electrostatic oscillation by using the linearized quantum hydrodynamic model in conjunction with Maxwell's equations was studied. The dispersion relation of a system of electron plasma in single-walled carbon nanotubes in the presence of an external magnetic field B 0 by considering the exchange-correlation effects in 2D cylindrical geometry is derived here. The uniform static magnetic field is assumed to be normal to the cylindrical surface (Voigt configuration). Distribution of the electrons and ions are considered uniformly over the cylindrical surface of a nanotube. It is found that the external magnetic field has significant impact on the wave in the longer wavelength. The influence of variation in azimuthal index and radius of the nanotube on dispersion relation is also discussed. It is tried to plot some schemes and analyze numerically in different limits of cylindrical and planar geometries. The results can be important in the study of collective phenomena in nanostructures.

  20. Carbon Nanotube Based Deuterium Ion Source for Improved Neutron Generators

    SciTech Connect

    Fink, R. L.; Jiang, N.; Thuesen, L.; Leung, K. N.; Antolak, A. J.

    2009-03-10

    Field ionization uses high electric fields to cause the ionization and emission of ions from the surface of a sharp electrode. We are developing a novel field ionization neutron generator using carbon nanotubes (CNT) to produce the deuterium ion current. The generator consists of three major components: a deuterium ion source made of carbon nanotubes, a smooth negatively-biased target electrode, and a secondary electron suppression system. When a negative high voltage is applied on the target electrode, a high gradient electric field is formed at the tips of the carbon nanotubes. This field is sufficiently strong to create deuterium (D) ions at or near the nanotubes which are accelerated to the target causing D-D reactions to occur and the production of neutrons. A cross magnetic field is used to suppress secondary emission electrons generated on the target surface. We have demonstrated field ionization currents of 70 nA (1 {mu}A/cm{sup 2}) at hydrogen gas pressure of 10 mTorr. We have found that the current scales proportionally with CNT area and also with the gas pressure in the range of 1 mTorr to 10 mTorr. We have demonstrated pulse cut-off times as short as 2 {mu}sec. Finally, we have shown the feasibility of generating neutrons using deuterium gas.

  1. Barrow Black Carbon Source and Impact Study Final Campaign Report

    SciTech Connect

    Barrett, Tate

    2014-07-01

    The goal of the Barrow Black Carbon Source and Impact (BBCSI) Study was to characterize the concentration and isotopic composition of carbonaceous atmospheric particulate matter (PM) at the Atmospheric Radiation Measurement site in Barrow, AK. The carbonaceous component was characterized via measurement of the organic and black carbon (OC and BC) components of the total PM. To facilitate complete characterization of the particulate matter, filter-based collections were used, including a medium volume PM2.5 sampler and a high volume PM10 sampler. Thirty-eight fine (PM2.5) and 49 coarse (PM10) particulate matter fractions were collected at weekly and bi-monthly intervals. The PM2.5 sampler operated with minimal maintenance during the 12 month campaign. The PM10 sampler used for the BBCSI used standard Tisch hi-vol motors which have a known lifetime of ~1 month under constant use; this necessitated monthly maintenance and it is suggested that the motors be upgraded to industrial blowers for future deployment in the Arctic. The BBCSI sampling campaign successfully collected and archived 87 ambient atmospheric particulate matter samples from Barrow, AK from July 2012 to June 2013. Preliminary analysis of the organic and black carbon concentrations has been completed. This campaign confirmed known trends of high BC lasting from the winter through to spring haze periods and low BC concentrations in the summer.

  2. Evaluation of Pyrolysis Oil as Carbon Source for Fungal Fermentation

    PubMed Central

    Dörsam, Stefan; Kirchhoff, Jennifer; Bigalke, Michael; Dahmen, Nicolaus; Syldatk, Christoph; Ochsenreither, Katrin

    2016-01-01

    Pyrolysis oil, a complex mixture of several organic compounds, produced during flash pyrolysis of organic lignocellulosic material was evaluated for its suitability as alternative carbon source for fungal growth and fermentation processes. Therefore several fungi from all phyla were screened for their tolerance toward pyrolysis oil. Additionally Aspergillus oryzae and Rhizopus delemar, both established organic acid producers, were chosen as model organisms to investigate the suitability of pyrolysis oil as carbon source in fungal production processes. It was observed that A. oryzae tolerates pyrolysis oil concentrations between 1 and 2% depending on growth phase or stationary production phase, respectively. To investigate possible reasons for the low tolerance level, eleven substances from pyrolysis oil including aldehydes, organic acids, small organic compounds and phenolic substances were selected and maximum concentrations still allowing growth and organic acid production were determined. Furthermore, effects of substances to malic acid production were analyzed and compounds were categorized regarding their properties in three groups of toxicity. To validate the results, further tests were also performed with R. delemar. For the first time it could be shown that small amounts of phenolic substances are beneficial for organic acid production and A. oryzae might be able to degrade isoeugenol. Regarding pyrolysis oil toxicity, 2-cyclopenten-1-on was identified as the most toxic compound for filamentous fungi; a substance never described for anti-fungal or any other toxic properties before and possibly responsible for the low fungal tolerance levels toward pyrolysis oil. PMID:28066378

  3. Evaluation of Pyrolysis Oil as Carbon Source for Fungal Fermentation.

    PubMed

    Dörsam, Stefan; Kirchhoff, Jennifer; Bigalke, Michael; Dahmen, Nicolaus; Syldatk, Christoph; Ochsenreither, Katrin

    2016-01-01

    Pyrolysis oil, a complex mixture of several organic compounds, produced during flash pyrolysis of organic lignocellulosic material was evaluated for its suitability as alternative carbon source for fungal growth and fermentation processes. Therefore several fungi from all phyla were screened for their tolerance toward pyrolysis oil. Additionally Aspergillus oryzae and Rhizopus delemar, both established organic acid producers, were chosen as model organisms to investigate the suitability of pyrolysis oil as carbon source in fungal production processes. It was observed that A. oryzae tolerates pyrolysis oil concentrations between 1 and 2% depending on growth phase or stationary production phase, respectively. To investigate possible reasons for the low tolerance level, eleven substances from pyrolysis oil including aldehydes, organic acids, small organic compounds and phenolic substances were selected and maximum concentrations still allowing growth and organic acid production were determined. Furthermore, effects of substances to malic acid production were analyzed and compounds were categorized regarding their properties in three groups of toxicity. To validate the results, further tests were also performed with R. delemar. For the first time it could be shown that small amounts of phenolic substances are beneficial for organic acid production and A. oryzae might be able to degrade isoeugenol. Regarding pyrolysis oil toxicity, 2-cyclopenten-1-on was identified as the most toxic compound for filamentous fungi; a substance never described for anti-fungal or any other toxic properties before and possibly responsible for the low fungal tolerance levels toward pyrolysis oil.

  4. Constrained Maximum Likelihood Estimation for Model Calibration Using Summary-level Information from External Big Data Sources

    PubMed Central

    Chatterjee, Nilanjan; Chen, Yi-Hau; Maas, Paige; Carroll, Raymond J.

    2016-01-01

    Information from various public and private data sources of extremely large sample sizes are now increasingly available for research purposes. Statistical methods are needed for utilizing information from such big data sources while analyzing data from individual studies that may collect more detailed information required for addressing specific hypotheses of interest. In this article, we consider the problem of building regression models based on individual-level data from an “internal” study while utilizing summary-level information, such as information on parameters for reduced models, from an “external” big data source. We identify a set of very general constraints that link internal and external models. These constraints are used to develop a framework for semiparametric maximum likelihood inference that allows the distribution of covariates to be estimated using either the internal sample or an external reference sample. We develop extensions for handling complex stratified sampling designs, such as case-control sampling, for the internal study. Asymptotic theory and variance estimators are developed for each case. We use simulation studies and a real data application to assess the performance of the proposed methods in contrast to the generalized regression (GR) calibration methodology that is popular in the sample survey literature. PMID:27570323

  5. Barrow Black Carbon Source and Impact Study Final Campaign Report

    SciTech Connect

    Barrett, Tate

    2014-07-01

    The goal of the Barrow Black Carbon Source and Impact campaign was to characterize the concentration and isotopic composition of carbonaceous atmospheric particulate matter (PM) at the Atmospheric Radiation Measurement (ARM) Climate Research Facility site in Barrow, Alaska. The carbonaceous component was characterized by measuring the organic and black carbon (OC and BC) components of the total PM. To facilitate complete characterization of the PM, filter-based collections were used, including a medium volume PM2.5 sampler and a high volume PM10 sampler. Thirty-eight fine PM fractions (PM2.5) and 49 coarse (PM10) PM fractions were collected at weekly and bi-monthly intervals. The PM2.5 sampler operated with minimal maintenance during the 12 month campaign. The PM10 sampler used for the Barrow Black Carbon Source and Impact (BBCSI) study used standard Tisch “hi-vol” motors that have a known lifetime of approximately 1 month under constant use; this necessitated monthly maintenance, and it is suggested that, for future deployment in the Arctic, the motors be upgraded to industrial blowers. The BBCSI sampling campaign successfully collected and archived 87 ambient atmospheric PM samples from Barrow, Alaska, from July 2012 to June 2013. Preliminary analysis of the OC and BC concentrations has been completed. This campaign confirmed known trends of high BC lasting from the winter through to spring haze periods and low BC concentrations in the summer. However, the annual OC concentrations had a very different seasonal pattern with the highest concentrations during the summer, lowest concentrations during the fall, and increased concentrations during the winter and spring (Figure 1).

  6. Production of intense ion beams in a reflex triode with an external plasma source at the anode

    SciTech Connect

    Bystritskii, V.M.; Verigin, A.A.; Volkov, S.N.; Krasik, Y.E.; Podkatov, V.I.

    1986-09-01

    An experimental study of the production of intense ion beams in a reflex triode with an external plasma source at the anode is reported. The ions had various ratios Z/M. When the anode plasma is produced in a preliminary charging pulse of the accelerator, the plasma density is too low for operation under charge-limited emission conditions. In this case, an ion beam is observed to be produced from the plasma formed by the direct heating of the anode material by oscillating electrons. When an anode plasma resulting from the breakdown of a dielectric insert or of the vacuum gap of a composite andode by an external voltage source is used to produce an ion beam, the reflex triode operating conditions depend on delaying the operation of the accelerator with respect to the external source. The highest efficiency (approx. =20%) in the production of an ion beam is observed at t/sub d/ = 3--6 ..mu..s. In this case, the reflex triode operates under increasing or constant impedance conditions. It was shown in the course of the experiments that the ion beam which is produced is nonuniform. There are three groups of ions: H/sup +/, C/sup n//sup +/, and Cu/sup n//sup +/. The energy of the heavy ions depends on the applied anode potential. The different mass components of the ion beam do not appear at the same time. The macroscopic divergence of the beam is 4--6/sup 0/ at the periphery and drops off to approx. <1/sup 0/ at the center. The microscopic divergence of the beam is 3/sup 0/. The total energy of the ion beam which is produced is less than 120 J at an average current approx. =2.8 kA.

  7. A look ahead: Status of the SNS external antenna ion source and the new RFQ test stand

    SciTech Connect

    Welton, R. F. Aleksandrov, A.; Han, B. X.; Murray, S. N.; Pennisi, T. R.; Piller, M.; Kang, Y.; Santana, M.; Stockli, M. P.; Dudnikov, V. G.

    2015-04-08

    The U.S. Spallation Neutron Source (SNS) now operates with ∼1 MW of beam power to target with the near-term goal of delivering 1.4 MW. Plans are being considered to incorporate a second target station into the facility which will require ∼2.8 MW of beam power. Presently, H{sup −} beam pulses (∼1 ms, 60 Hz) are produced by an RF-driven, Cs-enhanced, multi-cusp ion source which injects beam into an RFQ (Radio Frequency Quadrupole) accelerator that, in turn, feeds the SNS Linac. Currently the source/RFQ system delivers ∼35 mA of pulsed current to the linac which is mostly sufficient for 1.4 MW operations while ∼50 mA are needed for the second target station upgrade. This paper provides a look forward for the SNS by providing (i) the present and future SNS source/RFQ beam requirements and our plans to achieve these, (ii) a description and status of the external antenna ion source being developed for the replacement of the current internal antenna ion source, and (iii) a description and status of the newly constructed RFQ test facility.

  8. Seasonal Sources of Carbon Exports in a Headwater Stream

    NASA Astrophysics Data System (ADS)

    Argerich, A.; Johnson, S. L.

    2013-12-01

    Climate change is intimately tied to changes in carbon (C) budgets. Understanding the compartments and processes involved in the global C cycle across a landscape is essential to predict future climate change scenarios. While most C budgets focus on terrestrial contributions, river systems contribute to the C cycle by the export of total organic carbon (TOC) and dissolved inorganic carbon (DIC) to the ocean and by exporting CO2 to the atmosphere. Although headwater streams constitute between 60 and 80 percent of fluvial systems their role in the C cycle has often been neglected due to the methodological constrains derived from their heterogeneous morphology. Here we present an analysis of the temporal variation of C export both downstream and evaded to the atmosphere for a headwater stream draining a forested watershed. We relate it to in-stream metabolic processes (respiration and primary production) and to different carbon pools. Specifically, we estimate downstream exports of C in the form of dissolved organic (DOC), dissolved inorganic (DIC), and particulate organic (POC); we estimate the C content in the fine benthic organic matter (FBOM), dead wood, algae, and macroinvertebrate pools; and finally, the amount of CO2 originated and fixed by stream respiration and primary production. Organic exports, both particulate and dissolved, represented 39.7% of the annual downstream export of C while dissolved inorganic C represented 60.3%. Higher exports were observed during periods of high flow (late fall and winter). Highest seasonality in downstream exports was observed for POC (89.5% coefficient of variation in mean monthly fluxes), followed by DOC and DIC (24.3% and 15.9% respectively). Dissolved CO2 had mostly an autochthonous origin during summer (i.e. from stream ecosystem respiration) and originated from allochthonous sources during the rain-dominated months in Oregon (late fall and winter). The stream was net heterotrophic and the amount of C cycled through

  9. Soil carbon dioxide emissions from the Mojave desert: Isotopic evidence for a carbonate source

    NASA Astrophysics Data System (ADS)

    Soper, Fiona M.; McCalley, Carmody K.; Sparks, Kimberlee; Sparks, Jed P.

    2017-01-01

    Arid soils represent a substantial carbonate pool and may participate in surface-atmosphere CO2 exchange via a diel cycle of carbonate dissolution and exsolution. We used a Keeling plot approach to determine the substrate δ13C of CO2 emitted from carbonate-dominated soils in the Mojave desert and found evidence for a nonrespiratory source that increased with surface temperature. In dry soils at 25-30°C, the CO2 substrate had δ13C values of -19.4 ± 4.2‰, indicative of respiration of organic material (soil organic matter = -23.1 ± 0.8‰). CO2 flux increased with temperature; maximum fluxes occurred above 60°C, where δ13CO2 substrate (-7.2‰ ± 2.8‰) approached soil carbonate values (0.2 ± 0.2‰). In wet soils, CO2 emissions were not temperature dependent, and δ13CO2 substrate was lower in vegetated soils with higher flux rates, higher organic C content, and potential root respiration. These data provide the first direct evidence of CO2 emissions from alkaline desert soils derived from an abiotic source and that diurnal emission patterns are strongly driven by surface temperature.

  10. A 3T external source quadrupole Fourier transform mass spectrometer for ion/molecule reactions and analysis

    NASA Astrophysics Data System (ADS)

    McCullough, Sési M.; Gard, Eric; Lebrilla, Carlito B.

    1991-06-01

    A versatile quadrupole Fourier transform mass spectrometry instrument for both ion/molecule chemistry and analysis is described. Preliminary results show that despite the relatively low field (3T), a large mass range (up to m/z 16 000) and high resolution (41 000 FWHH at m/z 1692) are obtained. Metal ions (e.g. Fe+) for ion/molecule chemistry and organic ions (e.g. maltose) for analysis are routinely produced via secondary ion mass spectrometry (and liquid secondary ion mass spectrometry) in the external source.

  11. One-step synthesis of intrinsically functionalized fluorescent carbon nanoparticles by hydrothermal carbonization from different carbon sources

    NASA Astrophysics Data System (ADS)

    Shen, Chen; Yao, Wei; Lu, Yun

    2013-10-01

    Highly functionalized carbon nanoparticles (F-CNPs) with average sizes of 5-30 nm were fabricated by hydrothermal carbonization of specific carbon sources at a mild temperature without usual strong acid treatment or surface modification. The morphology, structure, and fluorescent properties of the nanoparticles were characterized by transmission electron microscopy, dynamic light scattering, Fourier-transform infrared spectra, X-ray photoelectron spectroscopy, Raman spectra and fluorescent spectrophotometer. As a result, the abundant carboxylic, sulfonic, amine, or ethanamide groups were furnished on the surface of these carbon nanoparticles, offering the reaction sites for their possible further functionalization, and these functional groups also enhance the dispersion of carbon nanoparticles which are kept without precipitation for months. The hydrothermal treatment which is simple, green, and economical, also can endow the F-CNPs much more carboxyl groups, thus improving the quantum efficiency of as-prepared products. These functionalized carbon nanoparticles demonstrate the excitation wavelength-independent photoluminescence behavior, implying their potential applications in biological labeling, imaging, and chromatography.

  12. Three-dimensional extremely-short optical pulses in carbon nanotube arrays in the presence of an external magnetic field

    NASA Astrophysics Data System (ADS)

    Zhukov, Alexander V.; Bouffanais, Roland; Belonenko, Mikhail B.; Galkina, Elena N.

    2016-12-01

    In this paper, we study the behavior of three-dimensional extremely-short optical pulses propagating in a system made of carbon nanotubes in the presence of an external magnetic field applied perpendicular both to the nanotube axis and to the direction of propagation of the pulse. The evolution of the electromagnetic field is classically derived on the basis of the Maxwell’s equations. The electronic system of carbon nanotubes is considered in the low-temperature approximation. Our analysis reveals the novel and unique ability of controlling the shape of propagating short optical pulses by tuning the intensity of the applied magnetic field. This effect paves the way for the possible development of innovative applications in optoelectronics.

  13. An analysis of external sources for revenue solicitation for optometric education.

    PubMed

    Banwell, B B

    1992-12-01

    In analyzing the costs of optometric education, it becomes apparent that the cost of operating the educational institution far exceeds the cost of providing the optometric education. A recent survey also indicates that there are rather striking differences in the cost of operating state-sponsored vs. private programs. It is necessary, therefore, to seek alternative sources of funding optometric education rather than relying on annual tuition escalation to cover increasing costs. Such sources include: realistic fees for clinic program services; various forms of state grants, private institution programs, tuition subsidies; foundations; gifts; "industrial partnerships" outside the ophthalmic field; and innovative financing.

  14. Comparing carbon sequestration potential of pyrogenic carbon from natural and anthropogenic sources

    NASA Astrophysics Data System (ADS)

    Santin, Cristina; Doerr, Stefan; Merino, Augustin

    2014-05-01

    The enhanced resistance to environmental degradation of Pyrogenic Carbon (PyC), both produced in wildfires (charcoal), and man-made (biochar), gives it the potential to sequester carbon by preventing it to be released into the atmosphere. Sustainable addition of biochar to soils is seen as a viable global approach for carbon sequestration and climate change mitigation. Also the role of its 'natural counterpart', i.e. wildfire charcoal, as a long-term carbon sink in soils is widely recognized. However, in spite of their fundamental similarities, research on the potential of 'man-made' biochar and wildfire charcoal for carbon sequestration has been carried out essentially in isolation as analogous materials for accurate comparison are not easily available. Here we assess the carbon sequestration potential of man-made biochar and wildfire charcoal generated from the same material under known production conditions: (i) charcoal from forest floor and down wood produced during an experimental boreal forest fire (FireSmart, June 2012, NWT- Canada) and (ii) biochar produced from the same feedstock by slow pyrolysis [three treatments: 2 h at 350, 500 and 650°C, respectively]. The carbon sequestration potential of these PyC materials is given by the recalcitrance index, R50, proposed by Harvey et al. (2012). R50 is based on the relative thermal stability of a given PyC material to that of graphite and is calculated using thermogravimetric analyses. Our results show highest R50 for PyC materials produced from down wood than from forest floor, which points to the importance of feedstock chemical composition in determining the C sequestration potential of PyC both from natural (charcoal) and anthropogenic (biochar) sources. Moreover, production temperature is also a major factor affecting the carbon sequestration potential of the studied PyC materials, with higher R50 for PyC produced at higher temperatures. Further investigation on the similarities and differences between man

  15. Organic Carbon Sources in Coastal Southeast Alaskan Streams

    NASA Astrophysics Data System (ADS)

    Hood, E.; Edwards, R. T.; D'Amore, D. V.; Lange, B. J.

    2003-12-01

    Dissolved organic matter (DOM) is abundant in southeast Alaskan watersheds and plays an important role in the biological and physical processes in these aquatic systems. Nearly 30% of the land area in southeast Alaska is classified as wetlands, a large proportion of which are peatlands. Peatlands are thought to provide substantial DOM to surface waters. Another important source of carbon to streams is spawning anadromous salmon. This study examines how streamwater concentrations of DOC are influenced by 1) catchments soils and vegetation, particularly wetland extent and 2) the presence or absence of anadromous fish. Our goal is to characterize the quantity and quality of different DOM sources and to develop an understanding of how these sources influence seasonal trends in streamwater DOM in coastal freshwater systems in southeast Alaska. Surface water and well samples were collected on two contrasting streams near Juneau, Alaska: Peterson Creek, a brownwater, high-carbon stream in a wetland-dominated catchment and McGinnis Creek, a clearwater stream draining upland spruce forest and alpine tundra. Both streams have runs of pink, coho, and chum salmon from July-September. Streamwater DOC concentrations on Peterson Creek averaged 5-6 mg C L-1 during the early summer and increased to 8-12 mg C L-1 during late July and August. Streamwater DOC concentrations on McGinnis Creek were typically less than 1 mg C L-1 during the early summer but increased dramatically to 4-9 mg C L-1 during spates in August. Well samples collected upslope from the streamwater sampling sites on Peterson and McGinnis Creeks had a similar range in DOC concentrations (10-40 mg C L-1), however the wells on McGinnis Creek showed much higher seasonal variability. Our initial results suggest that the seasonal increase in DOC in both streams is primarily associated with the flushing of soluble organic carbon from catchment soils by late summer rains. However, leaching of DOC from salmon carcasses may

  16. Nitrogen Source and External Medium pH Interaction Differentially Affects Root and Shoot Metabolism in Arabidopsis

    PubMed Central

    Sarasketa, Asier; González-Moro, M. Begoña; González-Murua, Carmen; Marino, Daniel

    2016-01-01

    Ammonium nutrition often represents an important growth-limiting stress in plants. Some of the symptoms that plants present under ammonium nutrition have been associated with pH deregulation, in fact external medium pH control is known to improve plants ammonium tolerance. However, the way plant cell metabolism adjusts to these changes is not completely understood. Thus, in this work we focused on how Arabidopsis thaliana shoot and root respond to different nutritional regimes by varying the nitrogen source (NO3- and NH4+), concentration (2 and 10 mM) and pH of the external medium (5.7 and 6.7) to gain a deeper understanding of cell metabolic adaptation upon altering these environmental factors. The results obtained evidence changes in the response of ammonium assimilation machinery and of the anaplerotic enzymes associated to Tricarboxylic Acids (TCA) cycle in function of the plant organ, the nitrogen source and the degree of ammonium stress. A greater stress severity at pH 5.7 was related to NH4+ accumulation; this could not be circumvented in spite of the stimulation of glutamine synthetase, glutamate dehydrogenase, and TCA cycle anaplerotic enzymes. Moreover, this study suggests specific functions for different gln and gdh isoforms based on the nutritional regime. Overall, NH4+ accumulation triggering ammonium stress appears to bear no relation to nitrogen assimilation impairment. PMID:26870054

  17. A Novel Airborne Carbon Isotope Analyzer for Methane and Carbon Dioxide Source Fingerprinting

    NASA Astrophysics Data System (ADS)

    Berman, E. S.; Huang, Y. W.; Owano, T. G.; Leifer, I.

    2014-12-01

    Recent field studies on major sources of the important greenhouse gas methane (CH4) indicate significant underestimation of methane release from fossil fuel industrial (FFI) and animal husbandry sources, among others. In addition, uncertainties still exist with respect to carbon dioxide (CO2) measurements, especially source fingerprinting. CO2 isotopic analysis provides a valuable in situ measurement approach to fingerprint CH4 and CO2as associated with combustion sources, leakage from geologic reservoirs, or biogenic sources. As a result, these measurements can characterize strong combustion source plumes, such as power plant emissions, and discriminate these emissions from other sources. As part of the COMEX (CO2 and MEthane eXperiment) campaign, a novel CO2 isotopic analyzer was installed and collected data aboard the CIRPAS Twin Otter aircraft. Developing methods to derive CH4 and CO2 budgets from remote sensing data is the goal of the summer 2014 COMEX campaign, which combines hyperspectral imaging (HSI) and non-imaging spectroscopy (NIS) with in situ airborne and surface data. COMEX leverages the synergy between high spatial resolution HSI and moderate spatial resolution NIS. The carbon dioxide isotope analyzer developed by Los Gatos Research (LGR) uses LGR's patented Off-Axis ICOS (Integrated Cavity Output Spectroscopy) technology and incorporates proprietary internal thermal control for high sensitivity and optimal instrument stability. This analyzer measures CO2 concentration as well as δ13C, δ18O, and δ17O from CO2 at natural abundance (100-3000 ppm). The laboratory accuracy is ±1.2 ppm (1σ) in CO2 from 370-1000 ppm, with a long-term (1000 s) precision of ±0.012 ppm. The long-term precision for both δ13C and δ18O is 0.04 ‰, and for δ17O is 0.06 ‰. The analyzer was field-tested as part of the COWGAS campaign, a pre-cursor campaign to COMEX in March 2014, where it successfully discriminated plumes related to combustion processes associated with

  18. Models for pulmonary lethality and morbidity after irradiation from internal and external sources

    SciTech Connect

    Scott, B.R.; Filipy, R.E.; Hahn, E.F.

    1989-05-01

    This report provides a hazard-function model for estimating the risk of death from radiation pneumonitis and/or pulmonary fibrosis following a light-water nuclear power accident. A similar model is also provided for estimating the prevalence of respiratory functional morbidity among those that survive death from acute effects. Hazard-function models for lethality and for morbidity were constructed using the cumulative hazard estimator H, which is related to the risk estimator R through the equation R = 1-exp(-H). The estimator H can be calculated using information provided in the report. The method of calculation depends on the exposure scenario. In general, the total normalized dose X for lethality or for morbidity is calculated. For lethality, X = 1 corresponds to a median lethal dose (LD/sub 50/); for morbidity, X = 1 corresponds to a median effective dose (ED/sub 50/). H is related to X by the equation H = 1n(2)X/sup V/, where V depends on the type of radiation (or radiations) involved. Contributions to X can arise from each of two main modes of exposure: (1) brief exposure of the lung, at a relatively high dose rate, to mainly external gammas, followed by (2) chronic internal alpha, and/or beta, and/or gamma irradiation of the lung. Equations are provided for calculating the contributions to X from both modes of exposure. 73 refs., 16 figs., 2 tabs.

  19. Enhanced absorption performance of carbon nanostructure based metamaterials and tuning impedance matching behavior by an external AC electric field.

    PubMed

    Gholipur, Reza; Khorshidi, Zahra; Bahari, Ali

    2017-03-27

    Metamaterials have surprisingly broadened the range of available practical applications in new devices such as shielding, microwave absorbing, and novel antenna. More researches are related to the tuning DNG frequency bands of ordered or disordered metamaterials, and far less research has focused on the importance of impedance matching behavior, and is not effort and attention in adjusting the magnitude of negative permittivity values. This is particularly important if devices deal with low amplitude signals such as radio or TV antenna. The carbon/hafnium nickel oxide (C/Hf0.9Ni0.1Oy) nanocomposites with simultaneously negative permittivity and negative permeability, excellent metamaterial performance and good impedance matching could become an efficient alternative for the ordered metamaterials in wave-transparent, microwave absorbing, and solar energy harvesting fields. In this study, we prepared C/Hf0.9Ni0.1Oy nanocomposites by solvothermal method, and we clarified how the impedance matching and double negative (DNG) behaviors of C/Hf0.9Ni0.1Oy can be tuned by an external AC electric field created by electric quadrupole system. External electric field allows for the alignment of the well-dispersed nanoparticles of carbon with long-range orientations order. We believe that this finding broadens our understanding of moderate conductive material-based random metamaterials (MCMRMs), and provides a novel strategy for replacing high loss ordered or disordered metamaterials with MCMRMs.

  20. Production of proteinase on noncarbohydrate carbon sources by Pseudomonas aeruginosa.

    PubMed

    Morihara, K

    1965-09-01

    Proteinase production by Pseudomonas aeruginosa was studied in medium containing noncarbohydrate materials, especially various hydrocarbons, as the sole carbon source. On heavy oil, kerosene, n-paraffinic hydrocarbon of C(12), C(14), or C(16), and propylene glycol, the bacteria grew well and high protinase production was observed. However, production on paraffinic hydrocarbon differed remarkably with strains of varied origins. The elastase-positive strain, IFO 3455, showed abundant growth and high proteinase production on medium containing a paraffin of C(12), C(14), or C(16), whereas the elastase-negative strain, IFO 3080, showed little growth on the same medium. Neither elastase-positive nor elastase-negative strains, however, utilized n-paraffins of C(5) to C(10), or various aromatic hydrocarbons such as benzene, naphthalene, phenanthrene, and anthracene. The proteinases produced on the noncarbohydrate medium were identical with those produced in glucose medium.

  1. Assembling x-ray sources by carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Sessa, V.; Lucci, M.; Toschi, F.; Orlanducci, S.; Tamburri, E.; Terranova, M. L.; Ciorba, A.; Rossi, M.; Hampai, D.; Cappuccio, G.

    2007-05-01

    By the use of a chemical vapour deposition technique a series of metal wires (W, Ta, Steel ) with differently shaped tips have been coated by arrays of single wall carbon nanotubes (SWNT). The field emission properties of the SWNT deposits have been measured by a home made apparatus working in medium vacuum (10 -6- 10 -7 mbar) and the SWNT-coated wires have been used to fabricate tiny electron sources for X-ray tubes. To check the efficiency of the nanotube coated wires for X-ray generation has, a prototype X-ray tube has been designed and fabricated. The X-ray tube works at pressures about 10 -6 mbar. The target ( Al film) is disposed on a hole in the stainless steel sheath: this configuration makes unnecessary the usual Be window and moreover allows us to use low accelerating potentials (< 6 kV).

  2. Addressing sources of uncertainty in a global terrestrial carbon model

    NASA Astrophysics Data System (ADS)

    Exbrayat, J.; Pitman, A. J.; Zhang, Q.; Abramowitz, G.; Wang, Y.

    2013-12-01

    Several sources of uncertainty exist in the parameterization of the land carbon cycle in current Earth System Models (ESMs). For example, recently implemented interactions between the carbon (C), nitrogen (N) and phosphorus (P) cycles lead to diverse changes in land-atmosphere C fluxes simulated by different models. Further, although soil organic matter decomposition is commonly parameterized as a first-order decay process, the formulation of the microbial response to changes in soil moisture and soil temperature varies tremendously between models. Here, we examine the sensitivity of historical land-atmosphere C fluxes simulated by an ESM to these two major sources of uncertainty. We implement three soil moisture (SMRF) and three soil temperature (STRF) respiration functions in the CABLE-CASA-CNP land biogeochemical component of the coarse resolution CSIRO Mk3L climate model. Simulations are undertaken using three degrees of biogeochemical nutrient limitation: C-only, C and N, and C and N and P. We first bring all 27 possible combinations of a SMRF with a STRF and a biogeochemical mode to a steady-state in their biogeochemical pools. Then, transient historical (1850-2005) simulations are driven by prescribed atmospheric CO2 concentrations used in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Similarly to some previously published results, representing N and P limitation on primary production reduces the global land carbon sink while some regions become net C sources over the historical period (1850-2005). However, the uncertainty due to the SMRFs and STRFs does not decrease relative to the inter-annual variability in net uptake when N and P limitations are added. Differences in the SMRFs and STRFs and their effect on the soil C balance can also change the sign of some regional sinks. We show that this response is mostly driven by the pool size achieved at the end of the spin-up procedure. Further, there exists a six-fold range in the level

  3. Trends in the sources and sinks of carbon dioxide

    SciTech Connect

    Le Quere, Corrine; Raupach, Mike; Canadell, J.G.; Marland, Gregg; Bopp, Laurent; Ciais, Philippe; Friedlingstein, Pierre; Viovy, Nicolas; Conway, T.J.; Doney, Scott C.; Feely, R. A.; Foster, Pru; House, Joanna I; Prentice, Colin I.; Gurney, Kevin; Houghton, R.A.; Huntingford, Chris; Levy, Peter E.; Lomas, M. R.; Woodward, F. I.; Majkut, Joseph; Sarmiento, Jorge L.; Metzl, Nicolas; Ometto, Jean P; Randerson, James T.; Peters, Glen P; Running, Steven; Sitch, Stephen; Takahashi, Taro; Van der Werf, Guido

    2009-12-01

    Efforts to control climate change require the stabilization of atmospheric CO2 concentrations. This can only be achieved through a drastic reduction of global CO2 emissions. Yet fossil fuel emissions increased by 29% between 2000 and 2008, in conjunction with increased contributions from emerging economies, from the production and international trade of goods and services, and from the use of coal as a fuel source. In contrast, emissions from land-use changes were nearly constant. Between 1959 and 2008, 43% of each year's CO2 emissions remained in the atmosphere on average; the rest was absorbed by carbon sinks on land and in the oceans. In the past 50 years, the fraction of CO2 emissions that remains in the atmosphere each year has likely increased, from about 40% to 45%, and models suggest that this trend was caused by a decrease in the uptake of CO2 by the carbon sinks in response to climate change and variability. Changes in the CO2 sinks are highly uncertain, but they could have a significant influence on future atmospheric CO2 levels. It is therefore crucial to reduce the uncertainties.

  4. Carbon Nanotube/Magnesium Composite as a Hydrogen Source.

    PubMed

    Yu, Min Kyu; Se, Kwon Oh; Kim, Min Joong; Hwang, Jae Won; Yoon, Byoung Young; Kwon, Hyuk Sang

    2015-11-01

    Hydrogen produced using the steam reforming process contains sulfur and carbon monoxide that are harmful to the Pt catalyst in proton-exchange-membrane fuel cells (PEMFCs). However, CO-free hydrogen can be generated from the hydrolysis of either Al in strongly alkaline water or Mg in neutral water with chlorides such as sea water. The hydrogen generation rate from the hydrolysis of Mg is extremely slow and linearly proportional to the corrosion rate of Mg in chloride water. In this work, we fabricated a carbon nanotube (CNT)--reinforced Mg--matrix composite by Spark Plasma Sintering as a fast hydrogen generation source for a PEMFC. The CNTs distributed in the Mg matrix act as numerous local cathodes, and hence cause severe galvanic corrosion between the Mg-matrix anode and CNT-cathode in NaCl solution. It was found that the hydrogen generation rate from the hydrolysis of the 5 vol.% CNT/Mg composite is 3300 times faster than that of the Mg without CNTs due primarily to the galvanic corrosion effect.

  5. Microbial Diversity Indexes Can Explain Soil Carbon Dynamics as a Function of Carbon Source

    PubMed Central

    Maron, Pierre-Alain; Menasseri-Aubry, Safya; Sarr, Amadou; Lévêque, Jean; Mathieu, Olivier; Jolivet, Claudy; Leterme, Philippe; Viaud, Valérie

    2016-01-01

    Mathematical models do not explicitly represent the influence of soil microbial diversity on soil organic carbon (SOC) dynamics despite recent evidence of relationships between them. The objective of the present study was to statistically investigate relationships between bacterial and fungal diversity indexes (richness, evenness, Shannon index, inverse Simpson index) and decomposition of different pools of soil organic carbon by measuring dynamics of CO2 emissions under controlled conditions. To this end, 20 soils from two different land uses (cropland and grassland) were incubated with or without incorporation of 13C-labelled wheat-straw residue. 13C-labelling allowed us to study residue mineralisation, basal respiration and the priming effect independently. An innovative data-mining approach was applied, based on generalized additive models and a predictive criterion. Results showed that microbial diversity indexes can be good covariates to integrate in SOC dynamics models, depending on the C source and the processes considered (native soil organic carbon vs. fresh wheat residue). Specifically, microbial diversity indexes were good candidates to help explain mineralisation of native soil organic carbon, while priming effect processes seemed to be explained much more by microbial composition, and no microbial diversity indexes were found associated with residue mineralisation. Investigation of relationships between diversity and mineralisation showed that higher diversity, as measured by the microbial diversity indexes, seemed to be related to decreased CO2 emissions in the control soil. We suggest that this relationship can be explained by an increase in carbon yield assimilation as microbial diversity increases. Thus, the parameter for carbon yield assimilation in mathematical models could be calculated as a function of microbial diversity indexes. Nonetheless, given limitations of the methods used, these observations should be considered with caution and

  6. Simultaneous reconstruction of emission activity and attenuation coefficient distribution from TOF data, acquired with external transmission source.

    PubMed

    Panin, V Y; Aykac, M; Casey, M E

    2013-06-07

    The simultaneous PET data reconstruction of emission activity and attenuation coefficient distribution is presented, where the attenuation image is constrained by exploiting an external transmission source. Data are acquired in time-of-flight (TOF) mode, allowing in principle for separation of emission and transmission data. Nevertheless, here all data are reconstructed at once, eliminating the need to trace the position of the transmission source in sinogram space. Contamination of emission data by the transmission source and vice versa is naturally modeled. Attenuated emission activity data also provide additional information about object attenuation coefficient values. The algorithm alternates between attenuation and emission activity image updates. We also proposed a method of estimation of spatial scatter distribution from the transmission source by incorporating knowledge about the expected range of attenuation map values. The reconstruction of experimental data from the Siemens mCT scanner suggests that simultaneous reconstruction improves attenuation map image quality, as compared to when data are separated. In the presented example, the attenuation map image noise was reduced and non-uniformity artifacts that occurred due to scatter estimation were suppressed. On the other hand, the use of transmission data stabilizes attenuation coefficient distribution reconstruction from TOF emission data alone. The example of improving emission images by refining a CT-based patient attenuation map is presented, revealing potential benefits of simultaneous CT and PET data reconstruction.

  7. Exploring external time-dependent sources of H2O into Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Lara, Luisa-Maria; Lellouch, Emmanuel; González, Marta; Moreno, Raphael; Rengel, Miriam

    2014-05-01

    Recent observations (Cottini et al., 2012, and Moreno et al., 2012) and steady-state photochemical modelling (Moreno et al., 2012; Dobrijevic et al., 2014) indicate that the amounts of CO2 and H2O in Titan's stratosphere imply relatively inconsistent values of the OH/H2O input flux. Moreno et al. (2012) proposed that the oxygen source is time-variable, whereas Dobrijevic et al. (2014) arrived to the same conclusion of Moreno et al. (2012) that the HSO (Herschel Space Observatory) measured H2O profile is'inconsistent" with the CO2 abundance. Furthermore, Dobrijevic et al. (2014) also found that reconciliation was possible if abundances reported by Cottini et al. (2012) are correct instead, though in this situation and for an Enceladus source, their model tended to overpredict the thermospheric abundance of H2O , compared to the upper limit by Cui et al. (2009). We attempt to reconcile the H2O and CO2 observed profiles in Titan's atmosphere by considering several time-dependent scenarios for the infux/evolution of oxygen species. To explore this, we use a time-dependent photochemical model of Titan's atmosphere to calculate effective lifetimes and the response of Titan's oxygen compounds to changes in the oxygen input flux. We consider a time-variable Enceladus source, as well as the evolution of material delivered by a cometary impact. We will show results on effective H2O and CO2 effective lifetimes, on the feasibility of time-variable Enceladus source, and on an additional H2O loss-to-the-haze. Regarding CO2, we will analyse its production following a cometary impact. A summary on viable scenarios to explain the H2O / CO2 puzzle will be given. References Moreno, R., Lellouch, E., Lara, L. M., et al. 2012, Icarus, 221, 753. Cottini, V., Nixon, C. A., Jennings, D. E., et al. 2012, Icarus, 220, 855. Cui, J., Yelle, R. V., Vuitton, V., et al. 2009, Icarus, 200, 581. Dobrijevic, M., Hébrard, E., Loison, J., and Hickson, K. 2014, Icarus, 228, 324.

  8. Source forensics of black carbon aerosols from China.

    PubMed

    Chen, Bing; Andersson, August; Lee, Meehye; Kirillova, Elena N; Xiao, Qianfen; Kruså, Martin; Shi, Meinan; Hu, Ke; Lu, Zifeng; Streets, David G; Du, Ke; Gustafsson, Örjan

    2013-08-20

    The limited understanding of black carbon (BC) aerosol emissions from incomplete combustion causes a poorly constrained anthropogenic climate warming that globally may be second only to CO2 and regionally, such as over East Asia, the dominant driver of climate change. The relative contribution to atmospheric BC from fossil fuel versus biomass combustion is important to constrain as fossil BC is a stronger climate forcer. The source apportionment is the underpinning for targeted mitigation actions. However, technology-based "bottom-up" emission inventories are inconclusive, largely due to uncertain BC emission factors from small-scale/household combustion and open burning. We use "top-down" radiocarbon measurements of atmospheric BC from five sites including three city sites and two regional sites to determine that fossil fuel combustion produces 80 ± 6% of the BC emitted from China. This source-diagnostic radiocarbon signal in the ambient aerosol over East Asia establishes a much larger role for fossil fuel combustion than suggested by all 15 BC emission inventory models, including one with monthly resolution. Our results suggest that current climate modeling should refine both BC emission strength and consider the stronger radiative absorption associated with fossil-fuel-derived BC. To mitigate near-term climate effects and improve air quality in East Asia, activities such as residential coal combustion and city traffic should be targeted.

  9. Factors for Microbial Carbon Sources in Organic and Mineral Soils from Eastern United States Deciduous Forests

    SciTech Connect

    Stitt, Caroline R.

    2013-09-16

    Forest soils represent a large portion of global terrestrial carbon; however, which soil carbon sources are used by soil microbes and respired as carbon dioxide (CO2) is not well known. This study will focus on characterizing microbial carbon sources from organic and mineral soils from four eastern United States deciduous forests using a unique radiocarbon (14C) tracer. Results from the dark incubation of organic and mineral soils are heavily influenced by site characteristics when incubated at optimal microbial activity temperature. Sites with considerable differences in temperature, texture, and location differ in carbon source attribution, indicating that site characteristics play a role in soil respiration.

  10. Effect of carbon and nitrogen sources on neutral proteinase production by Pseudomonas aeruginosa.

    PubMed

    Nigam, J N; Pillai, K R; Baruah, J N

    1981-01-01

    A strain of Pseudomonas aeruginosa from soil produced large quantities of extracellular neutral proteinase and could utilize several organic substances as carbon and nitrogen sources for enzyme production. The growth media required the presence of a high amount of phosphate when glucose was the carbon source. The intermediates of citric-acid cycle acids supported the proteinase production more than any other carbon sources. However, complex nitrogenous substances supported enzyme production more efficiently. Higher concentration of casamino acids suppressed the protinase synthesis.

  11. Dissolved organic carbon source integration in an agricultural watershed

    NASA Astrophysics Data System (ADS)

    Hernes, P. J.; Spencer, R. G.; Dyda, R. Y.; Pellerin, B. A.; Bachand, P. A.; Bergamaschi, B. A.

    2012-12-01

    The dissolved organic carbon (DOC) chemistry and concentration at the mouth of a watershed represents an integrated signal of all sources and process that occur upstream of the mouth, however, the relative contributions of all those sources and processes to the chemistry and concentration is not equal. We sampled an agricultural watershed in the Sacramento River valley in California synoptically on multiple occasions in order to better identify the most important contributors to DOC chemistry. Our samples included headwater samples from native grasslands in three sub-catchments, samples within the agricultural portions of those sub-watersheds, samples near the conjunctions, and irrigation field inputs and outputs. DOC concentrations increase considerably in the agricultural portion of the watershed, demonstrating the impacts of anthropogenic disturbance of landscapes as well as the potential for local landscapes to contribute significantly to the overall DOC concentration and chemistry. The central sub-catchment in particular had significantly greater DOC concentrations, which appears to correspond to the much greater proportion of flood irrigation land management in this portion, as our field runoff measurements indicate much higher added DOC during flood irrigation than during furrow irrigation. Flow-weighted averaging of the three sub-catchment DOC concentrations does not replicate concentrations at the mouth (1-6 km downstream of the confluences), indicating the importance of in-stream processing and/or source inputs from riparian zones even along the mainstem. Optical characterization of DOC demonstrates changing chemistry from season to season, and differences in chemistry from different areas of the catchment. The storm-influenced spring sampling yielded higher carbon-specific UV absorbance at 254 nm (SUVA254), indicating a higher proportion of aromaticity, while the southern sub-catchment consistently yielded the highest spectral slope values, which

  12. Quality of horizontally aligned single-walled carbon nanotubes: Is methane as carbon source better than ethanol?

    NASA Astrophysics Data System (ADS)

    Gao, Fenglei; Zhang, Lijie; Yang, Yun; Huang, Shaoming

    2010-03-01

    Chemical vapor deposition (CVD) growth of horizontally aligned single-walled carbon nanotubes (SWNTs) was studied using two representative carbon source sources: ethanol and methane. The resulting SWNTs were compared for similar reaction conditions which were based on the formation of Ni metal nanoparticles selective electrochemical deposition (SED) on the defect sites of SWNTs. The products were analyzed by Raman spectroscopy and SEM. The results demonstrate that methane was much better carbon source for growing high quality horizontal alignment of SWNTs than ethanol due to the etching effects of OH radicals on the SWNTs.

  13. Dual-Carbon sources fuel the OCS deep-reef Community, a stable isotope investigation

    USGS Publications Warehouse

    Sulak, Kenneth J.; Berg, J.; Randall, Michael; Dennis, George D.; Brooks, R.A.

    2008-01-01

    The hypothesis that phytoplankton is the sole carbon source for the OCS deep-reef community (>60 m) was tested. Trophic structure for NE Gulf of Mexico deep reefs was analyzed via carbon and nitrogen stable isotopes. Carbon signatures for 114 entities (carbon sources, sediment, fishes, and invertebrates) supported surface phytoplankton as the primary fuel for the deep reef. However, a second carbon source, the macroalga Sargassum, with its epiphytic macroalgal associate, Cladophora liniformis, was also identified. Macroalgal carbon signatures were detected among 23 consumer entities. Most notably, macroalgae contributed 45 % of total carbon to the 13C isotopic spectrum of the particulate-feeding reef-crest gorgonian Nicella. The discontinuous spatial distribution of some sessile deep-reef invertebrates utilizing pelagic macroalgal carbon may be trophically tied to the contagious distribution of Sargassum biomass along major ocean surface features.

  14. Self-similar propagation in a graded-index nonlinear-fiber amplifier with an external source

    SciTech Connect

    Raju, Thokala Soloman; Panigrahi, Prasanta K.

    2010-04-15

    We present exact analytical solutions describing spatial bright, trigonometric, and kink-type of self-similar waves, as well as the trains of such waves to the nonlinear Schroedinger equation appropriately modified to model beam propagation in graded-index, nonlinear fiber amplifier with an external source. We show that this model is appropriate for the self-similar propagation in asymmetric twin-core fiber amplifier. The asymmetric twin-core fiber is composed of two adjoining, closely spaced, single mode fibers in which the active one is a graded-index nonlinear fiber and the passive one is a step-index fiber. We obtain these self-similar waves using a Moebius transformation. Our procedure is applicable both for self-focusing and self-defocusing Kerr nonlinearities.

  15. Perfect and robust phase-locking of a spin transfer vortex nano-oscillator to an external microwave source

    SciTech Connect

    Hamadeh, A.; Loubens, G. de Klein, O.; Locatelli, N.; Lebrun, R.; Grollier, J.; Cros, V.

    2014-01-13

    We study the synchronization of the auto-oscillation signal generated by the spin transfer driven dynamics of two coupled vortices in a spin-valve nanopillar to an external source. Phase-locking to the microwave field h{sub rf} occurs in a range larger than 10% of the oscillator frequency for drive amplitudes of only a few Oersteds. Using synchronization at the double frequency, the generation linewidth is found to decrease by more than five orders of magnitude in the phase-locked regime (down to 1 Hz, limited by the resolution bandwidth of the spectrum analyzer) in comparison to the free running regime (140 kHz). This perfect phase-locking holds for frequency detuning as large as 2 MHz, which proves its robustness. We also analyze how the free running spectral linewidth impacts the main characteristics of the synchronization regime.

  16. Single-shot measurements of laser-induced avalanche breakdown demonstrating spatial and temporal control by an external source

    NASA Astrophysics Data System (ADS)

    Woodbury, Daniel; Wahlstrand, Jared; Goers, Andy; Feder, Linus; Miao, Bo; Hine, George; Salehi, Fatholah; Milchberg, Howard

    2016-10-01

    We report on the use of single-shot supercontinuum spectral interferometry (SSSI) to make temporally and spatially resolved measurements of laser-induced avalanche breakdown in ambient air by a 200 ps pulse. By seeding the breakdown using an external 100 fs pulse, we demonstrate control over the timing and spatial characteristics of the avalanche. In addition, we calculate the collisional ionization rates at various laser intensities and demonstrate seeding of the avalanche breakdown both by multiphoton ionization and by photodetaching ions produced from a radioactive source. These observations provide proof-of-concept support for recent proposals to remotely measure radioactivity using laser-induced avalanche breakdown. This work supported by a DTRA, C-WMD Basic Research Program, and by the DOE NNSA Stewardship Science Graduate Fellowship, provided under Grant Number DE-NA0002135.

  17. Impact of internal and external Alkalinity fluxes on the carbonate system in the German Bight / SE North Sea - A model study for the years 2001 - 2009

    NASA Astrophysics Data System (ADS)

    Schwichtenberg, Fabian; Pätsch, Johannes; Amann, Thorben; Schartau, Markus; Thomas, Helmuth; Winde, Vera; Dellwig, Olaf; van Beusekom, Justus; Böttcher, Michael; Grashorn, Sebastian; Salt, Lesley

    2013-04-01

    Rising atmospheric CO2 concentrations may cause enhanced oceanic CO2 concentrations and thus ongoing acidification of the marine environment. Effects of acidification on the coastal ocean exhibit large variabilities due to shallow water column, tight benthic-pelagic coupling, nutrient cycling, and discharge from land. As a result of enhanced biogeochemical processes, seasonal pH variations in coastal and shelf regions can be up to an order of magnitude higher than in the open ocean and may potentially mask the decadal trend of decreasing pH. Total Alkalinity (TA) is an essential part of the carbonate system as it regulates the oceanic CO2 buffer capacity. Variations in TA are vital to understand observed pH variations. In the coastal zone variations in TA are particularly pronounced because of diverse external sources like river discharge, anaerobic degradation of organic material or methane fluxes in tidal flats in association with pore water exchange across the sediment-water interface. Beside these external fluxes TA also changes due to physical, chemical and biological processes. To better understand and quantify the effect of acidification in the southern North Sea as part of the northwest European Shelf we applied the ecosystem model ECOHAM with a prognostic treatment of TA. For the first step we included monthly varying TA and DIC concentrations of the main continental rivers draining to the North Sea. For the Dutch rivers we calculated these data from other parameters of the carbonate system (bicarbonate and pH) that have been measured in the respective estuaries. For the river Elbe we used data of TA and DIC concentrations that have been measured in the estuary. Simulation results reveal that the river contribution to TA flux is insufficient to explain the seasonal variations observed in the German Bight. As high summer concentrations remain unresolved in this model setup, elevated TA concentrations during summer in that area must originate from sources

  18. Carbon nanotube mode-locked vertical external-cavity surface-emitting laser

    NASA Astrophysics Data System (ADS)

    Seger, K.; Meiser, N.; Choi, S. Y.; Jung, B. H.; Yeom, D.-I.; Rotermund, F.; Okhotnikov, O.; Laurell, F.; Pasiskevicius, V.

    2014-03-01

    Mode-locking an optically pumped semiconductor disk laser has been demonstrated using low-loss saturable absorption containing a mixture of single-walled carbon nanotubes in PMM polymer. The modulator was fabricated by a simple spin-coating technique on fused silica substrate and was operating in transmission. Stable passive fundamental modelocking was obtained at a repetition rate of 613 MHz with a pulse length of 1.23 ps. The mode-locked semiconductor disk laser in a compact geometry delivered a maximum average output power of 136 mW at 1074 nm.

  19. From carbon sink to carbon source: extensive peat oxidation in insular Southeast Asia since 1990

    NASA Astrophysics Data System (ADS)

    Miettinen, Jukka; Hooijer, Aljosja; Vernimmen, Ronald; Liew, Soo Chin; Page, Susan E.

    2017-02-01

    Tropical peatlands of the western part of insular Southeast Asia have experienced extensive land cover changes since 1990. Typically involving drainage, these land cover changes have resulted in increased peat oxidation in the upper peat profile. In this paper we provide current (2015) and cumulative carbon emissions estimates since 1990 from peat oxidation in Peninsular Malaysia, Sumatra and Borneo, utilizing newly published peatland land cover information and the recently agreed Intergovernmental Panel on Climate Change (IPCC) peat oxidation emission values for tropical peatland areas. Our results highlight the change of one of the Earth’s most efficient long-term carbon sinks to a short-term emission source, with cumulative carbon emissions since 1990 estimated to have been in the order of 2.5 Gt C. Current (2015) levels of emissions are estimated at around 146 Mt C yr‑1, with a range of 132–159 Mt C yr‑1 depending on the selection of emissions factors for different land cover types. 44% (or 64 Mt C yr‑1) of the emissions come from industrial plantations (mainly oil palm and Acacia pulpwood), followed by 34% (49 Mt C yr‑1) of emissions from small-holder areas. Thus, altogether 78% of current peat oxidation emissions come from managed land cover types. Although based on the latest information, these estimates may still include considerable, yet currently unquantifiable, uncertainties (e.g. due to uncertainties in the extent of peatlands and drainage networks) which need to be focused on in future research. In comparison, fire induced carbon dioxide emissions over the past ten years for the entire equatorial Southeast Asia region have been estimated to average 122 Mt C yr‑1 (www.globalfiredata.org/_index.html). The results emphasise that whilst reducing emissions from peat fires is important, urgent efforts are also needed to mitigate the constantly high level of emissions arising from peat drainage, regardless of fire occurrence.

  20. Source apportionment of PM10 mass and particulate carbon in the Kathmandu Valley, Nepal

    NASA Astrophysics Data System (ADS)

    Kim, Bong Mann; Park, Jin-Soo; Kim, Sang-Woo; Kim, Hyunjae; Jeon, Haeun; Cho, Chaeyoon; Kim, Ji-Hyoung; Hong, Seungkyu; Rupakheti, Maheswar; Panday, Arnico K.; Park, Rokjin J.; Hong, Jihyung; Yoon, Soon-Chang

    2015-12-01

    The Kathmandu Valley in Nepal is a bowl-shaped urban basin in the Himalayan foothills with a serious problem of fine particulate air pollution that impacts local health and impairs visibility. Particulate carbon concentrations have reached severe levels that threaten the health of 3.5 million local residents. Moreover, snow and ice on the Himalayan mountains are melting as a result of additional warming due to particulate carbon, especially high black carbon concentrations. To date, the sources of the Valley's particulate carbon and the impacts of different sources on particulate carbon concentrations are not well understood. Thus, before an effective control strategy can be developed, these particulate carbon sources must be identified and quantified. Our study has found that the four primary sources of particulate carbon in the Kathmandu Valley during winter are brick kilns, motor vehicles, fugitive soil dust, and biomass/garbage burning. Their source contributions are quantified using a recently developed new multivariate receptor model SMP. In contrast to other highly polluted areas such as China, secondary contribution is almost negligible in Kathmandu Valley. Brick kilns (40%), motor vehicles (37%) and biomass/garbage burning (22%) have been identified as the major sources of elemental carbon (black carbon) in the Kathmandu Valley during winter, while motor vehicles (47%), biomass/garbage burning (32%), and soil dust (13%) have been identified as the most important sources of organic carbon. Our research indicates that controlling emissions from motor vehicles, brick kilns, biomass/garbage burning, and soil dust is essential for the mitigation of the particulate carbon that threatens public health, impairs visibility, and influences climate warming within and downwind from the Kathmandu Valley. In addition, this paper suggests several useful particulate carbon mitigation methods that can be applied to Kathmandu Valley and other areas in South Asia with

  1. Anaerobic biogranulation using phenol as the sole carbon source

    SciTech Connect

    Tay, J.H.; He, Y.X.; Yan, Y.G.

    2000-04-01

    The granulation process was extensively examined using phenol as sole carbon source in a 2-L laboratory upflow anaerobic sludge blanket (UASB) reactor. The study was conducted mesophilically at 35 C. Anaerobically digested sludge was used as seed after a 14-day activation period with glucose feed. Massive initial granules were developed after 3 months of startup, grew at an accelerated pace for 6 months, then became fully grown. The granulation process can be broken into three phases: acclimation, granulation, and maturation. However, granulation with phenol proceeded more slowly than it did in UASB reactors fed with readily biodegradable carbohydrates studied previously. The granular sludge cultivated had a median diameter of 1.8 mm, phenol-degrading activity of 0.65 g chemical oxygen demand (COD)/g volatile suspended solids (VSS){sm_bullet}d, and a sludge volume index of 14 mL/g. Phenol COD removal efficiency of 86% was achieved when the reactor was operating at an influent phenol concentration of 1,260 mg/L (corresponding to 3,000 mg COD/L), hydraulic retention time of 12 hours, and volumetric loading rate of 6 g COD/L{sm_bullet}d. However, the lower-than-expected phenol COD removal efficiency could be attributed to inhibition by the high influent phenol concentration or loading. The batch test demonstrated that the sludge methanogenic activity was reduced by 52 and 75% at phenol concentrations of 420 and 840 mg/L, respectively.

  2. Examining the Role of Multiple Carbon Sources in Isoprene Synthesis in Plants Using Stable Isotope Techniques

    NASA Astrophysics Data System (ADS)

    Funk, J. L.; Mak, J. E.; Lerdau, M. T.

    2001-12-01

    The carbon source for phytogenc isoprene is an issue with important ramifications for both atmospheric and biological science because of its impact on the isotopic signature of isoprene and its oxidation products and because it lends insight into the function that isoprene serves within leaves. Although recently assimilated carbon is believed to be the primary carbon source for isoprene production in plants, variation in diurnal and seasonal isoprene fluxes that cannot be explained by temperature, light, and leaf development have led to the suggestion that alternative carbon sources may contribute. Stable isotopes of carbon can be used to identify changes in carbon partitioning into isoprene synthesis, and mixing models can assess the relative importance of each source. In preliminary studies, we document an additional 8-10 \\permil discrimination in isoprene emitted in the absence of photosynthesis. This change in signature suggests that the carbon source is switched from recently obtained photosynthate to a source more depleted in 13C. We propose that intermediates from carbohydrate degradation and/or re-fixation of CO2 from mitichondrial respiration and photorespiration can contribute to isoprene production. In addition, we expect alternative carbon sources to be most important when photosynthate is limiting (e.g. during water stress events). Photosynthesis, respiration, and isoprene emission measurements are used to calculate the isotopic signatures of the three potential carbon pools: photosynthate derived from ambient CO2, photosynthate derived from respired CO2, and carbohydrate-derived intermediates.

  3. Young organic matter as a source of carbon dioxide outgassing from Amazonian rivers

    SciTech Connect

    Mayorga, E; Aufdenkampe, A K; Masiello, C A; Krusche, A V; Hedges, J I; Quay, P D; Richey, J E; Brown, T A

    2005-06-23

    Rivers are generally supersaturated with respect to carbon dioxide, resulting in large gas evasion fluxes that can be a significant component of regional net carbon budgets. Amazonian rivers were recently shown to outgas more than ten times the amount of carbon exported to the ocean in the form of total organic carbon or dissolved inorganic carbon. High carbon dioxide concentrations in rivers originate largely from in situ respiration of organic carbon, but little agreement exists about the sources or turnover times of this carbon. Here we present results of an extensive survey of the carbon isotope composition ({sup 13}C and {sup 14}C) of dissolved inorganic carbon and three size-fractions of organic carbon across the Amazonian river system. We find that respiration of contemporary organic matter (less than 5 years old) originating on land and near rivers is the dominant source of excess carbon dioxide that drives outgassing in mid-size to large rivers, although we find that bulk organic carbon fractions transported by these rivers range from tens to thousands of years in age. We therefore suggest that a small, rapidly cycling pool of organic carbon is responsible for the large carbon fluxes from land to water to atmosphere in the humid tropics.

  4. The Effect of Carbon Source and Fluoride Concentrations in the "Streptococcus Mutans" Biofilm Formation

    ERIC Educational Resources Information Center

    Paulino, Tony P.; Andrade, Ricardo O.; Bruschi-Thedei, Giuliana C. M.; Thedei, Geraldo, Jr.; Ciancaglini, Pietro

    2004-01-01

    The main objective of this class experiment is to show the influence of carbon source and of different fluoride concentrations on the biofilm formation by the bacterium "Streptococcus mutans." The observation of different biofilm morphology as a function of carbon source and fluoride concentration allows an interesting discussion regarding the…

  5. Externally limited defect generation in multiwalled carbon nanotubes upon thermal annealing, and possible mechanism

    NASA Astrophysics Data System (ADS)

    Bhalerao, G. M.; Sinha, A. K.; Srivastava, A. K.; Sathe, V.; Amarendra, G.

    2016-09-01

    Structural defects in multiwalled carbon nanotubes (MWCNTs) are found to increase upon moderate thermal annealing below 1400 K in an argon atmosphere. The defects are estimated using the ID/IG ratio in Raman spectroscopy of MWCNTs and confirmed by a direct observation using high-resolution transmission electron microscopy (HRTEM). HRTEM shows that the structural defects are created due to large damage to the outer walls of the nanotubes, while inner walls do not sustain any damage. The generation of defects on MWCNTs is attibuted to mechanical abrasion between the MWCNTs in contact, augmented by the momentum transfer from the flow of hot gas. A possible mechanism is proposed and experimentally validated by means of modulating the chemical environment of annealing from argon to hydrogen.

  6. External-Noise-Induced Small-Signal Detection with Solution-Gated Carbon Nanotube Transistor

    NASA Astrophysics Data System (ADS)

    Hakamata, Yasufumi; Ohno, Yasuhide; Maehashi, Kenzo; Inoue, Koichi; Matsumoto, Kazuhiko

    2011-04-01

    A solution-gated carbon nanotube field-effect transistor (CNTFET) based on stochastic resonance (SR) was investigated in order to enhance small-signal detection under ambient noise conditions. When noise of optimal intensity was introduced at the reference electrode in a nonlinear CNTFET, the electric double layer in the solution was modulated, resulting in SR behavior. Moreover, when the CNTFET was used as a pH sensor, high sensitivity was achieved, which enabled the detection of small differences in pH. The best results were obtained in a noisy environment; therefore, a solution-gated SR-based CNTFET operated in the subthreshold regime is a promising high-sensitivity sensor.

  7. Effect of carbon dioxide and bicarbonate as inorganic carbon sources on growth and adaptation of autohydrogenotrophic denitrifying bacteria.

    PubMed

    Ghafari, Shahin; Hasan, Masitah; Aroua, Mohamed Kheireddine

    2009-03-15

    Acclimation of autohydrogenotrophic denitrifying bacteria using inorganic carbon source (CO(2) and bicarbonate) and hydrogen gas as electron donor was performed in this study. In this regard, activated sludge was used as the seed source and sequencing batch reactor (SBR) technique was applied for accomplishing the acclimatization. Three distinct strategies in feeding of carbon sources were applied: (I) continuous sparging of CO(2), (II) bicarbonate plus continuous sparging of CO(2), and (III) only bicarbonate. The pH-reducing nature of CO(2) showed an unfavorable impact on denitrification rate; however bicarbonate resulted in a buffered environment in the mixed liquor and provided a suitable mean to maintain the pH in the desirable range of 7-8.2. As a result, bicarbonate as the only carbon source showed a faster adaptation, while carbon dioxide as the only carbon source as well as a complementary carbon source added to bicarbonate resulted in longer acclimation period. Adapted hydrogenotrophic denitrifying bacteria, using bicarbonate and hydrogen gas in the aforementioned pH range, caused denitrification at a rate of 13.33 mg NO(3)(-)-N/g MLVSS/h for degrading 20 and 30 mg NO(3)(-)-N/L and 9.09 mg NO(3)(-)-N/g MLVSS/h for degrading 50mg NO(3)(-)-N/L.

  8. Nitrite accumulation under constant temperature in anoxic denitrification process: The effects of carbon sources and COD/NO(3)-N.

    PubMed

    Ge, Shijian; Peng, Yongzhen; Wang, Shuying; Lu, Congcong; Cao, Xu; Zhu, Yunpeng

    2012-06-01

    Effects of external carbon sources and COD/NO(3)-N on nitrite accumulation through denitrification were studied at a temperature of 28±2.0 °C using mixed activated sludge. Nitrite accumulation was observed for each type of carbon source studied. Glucose resulted in the greatest nitrite accumulation and production rate, which were 14.51±2.41 mg/L and 0.121±0.013 g N/(g VSS d), respectively. Moreover, a higher COD/NO(3)-N ratio ranging from 1.0 to 15.0 increased accumulation to the maximum value of 0.34±0.03 g N/(g VSS d). It was assumed that the competition for electrons between nitrite reductase and nitrate reductase led to different reduction rates and finally caused the accumulation. In addition, it was reasonable to use the pH and ORP as proxies for monitoring the real endpoint of the denitrification process with the addition of carbon sources.

  9. Production of cellulase from Trichoderma reesei in fed-batch fermentation from soluble carbon sources

    SciTech Connect

    Allen, A.L.; Mortensen, R.E.

    1981-11-01

    The use of a soluble carbon source in lieu of cellulose for the production of cellulase would allow greater control of the fermentation, since growth and enzyme production would no longer be dependent upon cellulose hydrolysis. Where carbon limitation is a requirement, fed-batch fermentation has proved successful. This article describes cellulase production from Trichoderma reesei using five different carbon sources, sophorose appearing to be a more likely candidate than cellobiose. (Refs. 22).

  10. Investigating effectiveness of activated carbons of natural sources on various supercapacitors

    NASA Astrophysics Data System (ADS)

    Faisal, Md. Shahnewaz Sabit; Rahman, Muhammad M.; Asmatulu, Ramazan

    2016-04-01

    Activated carbon can be produced from natural sources, such as pistachio and acorn shells, which can be an inexpensive and sustainable sources of natural wastes for the energy storage devices, such as supercapacitors. The carbonaceous materials used in this study were carbonized at the temperatures of 700°C and 900°C after the stabilization process at 240°C for two hours. These shells showed approximately 60% carbon yield. Carbonized nutshells were chemically activated using1wt% potassium hydroxide (KOH). Activated carbon powders with polyvinylidene fluoride (PVdF) were used to construct carbon electrodes. A 1M of tetraethylammonium tetrafluoroborate (TEABF4) and propylene carbonate (PC) were used as electrolytes. Electrochemical techniques, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for the characterization of the supercapacitors. Scanning electron microscopy (SEM) was used to inspect the surface texture of the activated carbons. Activated pistachio shells carbonized at 700°C showed more porous surface texture than those carbonized at 900°C. Effects of the carbonization temperatures were studied for their electrochemical characteristics. The shells carbonized at 700°C showed better electrochemical characteristics compared to those carbonized at 900°C. The test results provided about 27,083 μF/g specific capacitance at a scan rate of 10mV/s. This study showed promising results for using these activated carbons produced from the natural wastes for supercapacitor applications.

  11. Impact Testing on Reinforced Carbon-Carbon Flat Panels With BX-265 and PDL-1034 External Tank Foam for the Space Shuttle Return to Flight Program

    NASA Technical Reports Server (NTRS)

    Melis, Matthew E.; Revilock, Duane M.; Pereira, Michael J.; Lyle, Karen H.

    2009-01-01

    Following the tragedy of the Orbiter Columbia (STS-107) on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the space shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize reinforced carbon-carbon (RCC) along with ice and foam debris materials, which could shed on ascent and impact the orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS-DYNA (Livermore Software Technology Corp.) to predict damage by potential and actual impact events on the orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: Level 1-fundamental tests to obtain independent static and dynamic constitutive model properties of materials of interest, Level 2-subcomponent impact tests to provide highly controlled impact test data for the correlation and validation of the models, and Level 3-full-scale orbiter leading-edge impact tests to establish the final level of confidence for the analysis methodology. This report discusses the Level 2 test program conducted in the NASA Glenn Research Center (GRC) Ballistic Impact Laboratory with external tank foam impact tests on flat RCC panels, and presents the data observed. The Level 2 testing consisted of 54 impact tests in the NASA GRC Ballistic Impact Laboratory on 6- by 6-in. and 6- by 12-in. flat plates of RCC and evaluated two types of debris projectiles: BX-265 and PDL-1034 external tank foam. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile and validated the use of the foam and RCC models for use in LS-DYNA.

  12. Application of plant carbon source for denitrification by constructed wetland and bioreactor: review of recent development.

    PubMed

    Hang, Qianyu; Wang, Haiyan; Chu, Zhaosheng; Ye, Bibi; Li, Chunmei; Hou, Zeying

    2016-05-01

    Water quality standard for nitrate becomes more and more strict, and the plant carbon source is widely used for denitrification by constructed wetland (CW) and bioreactor. However, the nitrate removal efficiency by different types of plant carbon source are not evaluated comprehensively. Denitrification performance of different plant carbon sources, and the influence of dosing method and pretreatment are thoroughly reviewed in this paper, which aims to investigate the accurate utilization of plant carbon source for nitrogen (as nitrate) removal. It is concluded that plant carbon source addition for all types of CWs and bioreactors can improve the nitrate removal efficiency to some extent, and the dosing method of plant carbon source for denitrification should be further studied and optimized in the future. The popular carbon sources for CW and bioreactor denitrification enhancement are woodchip, chopped macrophytes, crop plants, macrophytes litters, etc. The recommended optimum C:N ratios for CW and bioreactor are 4.0:5.0 and 1.8:3.0, respectively. The physical and biological pretreatments are selected to supply organic carbon for long-term denitrification.

  13. Stationary structure of a high-frequency discharge maintained by a distributed electromagnetic source in the presence of an external magnetic field

    SciTech Connect

    Es'kin, V. A.; Kudrin, A. V.

    2010-04-15

    The stationary structure of an axisymmetric high-frequency discharge maintained by a given source in an external dc magnetic field is investigated. The source is assumed to be a current wave that travels over the discharge tube surface in the direction of the external magnetic field. The source current has a single azimuthal component and its frequency belongs to the lower hybrid range. The main emphasis is placed on the special case where the electron heat conduction length across the external magnetic field exceeds considerably the tube radius. The dependences of discharge plasma parameters on the current amplitude and propagation constant along the tube have been found for this case. The results of numerical calculations of the distributions of the field and the power of the Joule loss in a discharge are presented.

  14. Responses of Pseudomonas putida to toxic aromatic carbon sources.

    PubMed

    Krell, Tino; Lacal, Jesús; Guazzaroni, M Eugenia; Busch, Andreas; Silva-Jiménez, Hortencia; Fillet, Sandy; Reyes-Darías, José A; Muñoz-Martínez, Francisco; Rico-Jiménez, Miriam; García-Fontana, Cristina; Duque, Estrella; Segura, Ana; Ramos, Juan-Luis

    2012-07-31

    A number of bacteria can use toxic compounds as carbon sources and have developed complex regulatory networks to protect themselves from the toxic effects of these compounds as well as to benefit from their nutritious properties. As a model system we have studied the responses of Pseudomonas putida strains to toluene. Although this compound is highly toxic, several strains are able to use it for growth. Particular emphasis was given to the responses in the context of taxis, resistance and toluene catabolism. P. putida strains analysed showed chemotactic movements towards toluene. Strain DOT-T1E was characterised by an extreme form of chemotaxis, termed hyperchemotaxis, which is mediated by the McpT chemoreceptor encoded by plasmid pGRT1. Close McpT homologs are found in a number of other plasmids encoding degradation pathways of toxic compounds. The pGRT1 plasmid harbours also the genes for the TtgGHI efflux pump which was identified as the primary determinant for the resistance of strain DOT-T1E towards toluene. Pump expression is controlled by the TtgV repressor in response to a wide range of different mono- and biaromatic compounds. Strain DOT-T1E is able to degrade toluene, benzene and ethylbenzene via the toluene dioxygenase (TOD) pathway. The expression of the pathway operon is controlled by the TodS/T two component system. The sensor kinase TodS recognizes toluene with nanomolar affinity, which in turn triggers an increase in its autophosphorylation and consequently transcriptional activation. Data suggest that transcriptional activation of the TOD pathway occurs at very low toluene concentrations whereas TtgV mediated induction of pump expression sets in as the toluene concentration further increases.

  15. Impact of external industrial sources on the regional and local SO₂ and O₃ levels of the Mexico megacity

    SciTech Connect

    Almanza, V. H.; Molina, Luisa T.; Li, Guohui; Fast, Jerome D.; Sosa, G.

    2014-08-22

    The air quality of megacities can be influenced by external emissions sources on both global and regional scale, and at the same time their outflow emissions can exert an important impact to the surrounding environment. The present study evaluates an SO₂ peak observed on 24 March 2006 at the suburban supersite T1 and ambient air quality monitoring stations located in the north region of the Mexico City Metropolitan Area (MCMA) during MILAGRO campaign. We found that this peak could be related to an important episodic emission event from Tizayuca region, northeast of the MCMA. Back trajectories analyses suggest that the emission event started in the early morning at 10 04:00 LST and lasted for about 9 h. The estimated emission rate is noticeably high, about 2 kgs-¹. This finding suggests the possibility of "overlooked"emission sources in this region that could influence the air quality of the MCMA. This further motivated us to study the cement plants, including those in the State of Hidalgo and in the State of Mexico, and we found that they can contribute in the NE region of the basin (about 15 41.7%), at the suburban supersite T1 (41.23%) and at some monitoring stations their contribution can be even higher than from the Tula Industrial Complex. The contribution of Tula Industrial Complex to regional ozone levels is estimated. The model suggests low contribution to the MCMA (1 ppb to 4 ppb) and slightly higher at the suburban T1 (6 ppb) and rural T2 (5 ppb) supersites. However, the contribution could be 20 as high as 10 ppb in the upper northwest region of the basin and in the southwest and south-southeast regions of State of Hidalgo. In addition, a first estimate of the potential contribution from flaring activities to regional ozone levels is presented. Emission rates are estimated with a CFD combustion model. Results suggest that up to 30% of the total regional ozone from TIC could be related to flaring activities. 25 Finally, the influence in SO₂ levels

  16. Impact of external industrial sources on the regional and local SO2 and O3 levels of the Mexico megacity

    NASA Astrophysics Data System (ADS)

    Almanza, V. H.; Molina, L. T.; Li, G.; Fast, J.; Sosa, G.

    2014-08-01

    The air quality of megacities can be influenced by external emission sources on both global and regional scales. At the same time their outflow emissions can exert an impact to the surrounding environment. The present study evaluates an SO2 peak observed on 24 March 2006 at the suburban supersite T1 and at ambient air quality monitoring stations located in the northern region of the Mexico City Metropolitan Area (MCMA) during the Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign. We found that this peak could be related to an important episodic emission event coming from Tizayuca region, northeast of the MCMA. Back-trajectory analyses suggest that the emission event started in the early morning at 04:00 LST and lasted for about 9 h. The estimated emission rate is about 2 kg s-1. To the best of our knowledge, sulfur dioxide emissions from the Tizayuca region have not been considered in previous studies. This finding suggests the possibility of "overlooked" emission sources in this region that could influence the air quality of the MCMA. This further motivated us to study the cement plants, including those in the state of Hidalgo and in the State of Mexico. It was found that they can contribute to the SO2 levels in the northeast (NE) region of the basin (about 42%), at the suburban supersite T1 (41%) and that at some monitoring stations their contribution can be even higher than the contribution from the Tula Industrial Complex (TIC). The contribution of the Tula Industrial Complex to regional ozone levels is estimated. The model suggests low contribution to the MCMA (1 to 4 ppb) and slightly higher contribution at the suburban T1 (6 ppb) and rural T2 (5 ppb) supersites. However, the contribution could be as high as 10 ppb in the upper northwest region of the basin and in the southwest and south-southeast regions of the state of Hidalgo. In addition, the results indicated that the ozone plume could also be transported to northwest

  17. The roles of inoculants' carbon source use in the biocontrol of potato scab disease.

    PubMed

    Sun, Pingping; Zhao, Xinbei; Shangguan, Nini; Chang, Dongwei; Ma, Qing

    2015-04-01

    Despite the application of multiple strains in the biocontrol of plant diseases, multistrain inoculation is still constrained by its inconsistency in the field. Nutrients, especially carbons, play an important role in the biocontrol processes. However, little work has been done on the systematic estimation of inoculants' carbon source use on biocontrol efficacies in vivo. In the present study, 7 nonpathogenic Streptomyces strains alone and in different combinations were inoculated as biocontrol agents against the potato scab disease, under field conditions and greenhouse treatments. The influence of the inoculants' carbon source use properties on biocontrol efficacies was investigated. The results showed that increasing the number of inoculated strains did not necessarily result in greater biocontrol efficacy in vivo. However, single strains with higher growth rates or multiple strains with less carbon source competition had positive effects on the biocontrol efficacies. These findings may shed light on optimizing the consistent biocontrol of plant disease with the consideration of inoculants' carbon source use properties.

  18. Dissolved black carbon in Antarctic lakes: Chemical signatures of past and present sources

    NASA Astrophysics Data System (ADS)

    Khan, Alia L.; Jaffé, Rudolf; Ding, Yan; McKnight, Diane M.

    2016-06-01

    The perennially ice-covered, closed-basin lakes in the McMurdo Dry Valleys, Antarctica, serve as sentinels for understanding the fate of dissolved black carbon from glacial sources in aquatic ecosystems. Here we show that dissolved black carbon can persist in freshwater and saline surface waters for thousands of years, while preserving the chemical signature of the original source materials. The ancient brines of the lake bottom waters have retained dissolved black carbon with a woody chemical signature, representing long-range transport of black carbon from wildfires. In contrast, the surface waters are enriched in contemporary black carbon from fossil fuel combustion. Comparison of samples collected 25 years apart from the same lake suggests that the enrichment in anthropogenic black carbon is recent. Differences in the chemical composition of dissolved black carbon among the lakes are likely due to biogeochemical processing such as photochemical degradation and sorption on metal oxides.

  19. Characterization of a Low-Cost Optical Flow Sensor When Using an External Laser as a Direct Illumination Source

    PubMed Central

    Font, Davinia; Tresanchez, Marcel; Pallejà, Tomàs; Teixidó, Mercè; Palacín, Jordi

    2011-01-01

    In this paper, a low cost optical flow sensor is combined with an external laser device to measure surface displacements and mechanical oscillations. The measurement system is based on applying coherent light to a diffuser surface and using an optical flow sensor to analyze the reflected and transferred light to estimate the displacement of the surface or the laser spot. This work is focused on the characterization of this measurement system, which can have the optical flow sensor placed at different angles and distances from the diffuser surface. The results have shown that the displacement of the diffuser surface is badly estimated when the optical mouse sensor is placed in front of the diffuser surface (angular orientation >150°) while the highest sensitivity is obtained when the sensor is located behind the diffuser surface and on the axis of the laser source (angular orientation 0°). In this case, the coefficient of determination of the measured displacement, R2, was very high (>0.99) with a relative error of less than 1.29%. Increasing the distance between the surface and the sensor also increased the sensitivity which increases linearly, R2 = 0.99. Finally, this measurement setup was proposed to measure very low frequency mechanical oscillations applied to the laser device, up to 0.01 Hz in this work. The results have shown that increasing the distance between the surface and the optical flow sensor also increases the sensitivity and the measurement range. PMID:22247696

  20. Natural sources of greenhouse gases: carbon dioxide emissions from volcanoes

    USGS Publications Warehouse

    Gerlach, Terrence

    1990-01-01

    Volcanic degassing of carbon dioxide plays an important role in keeping the atmosphere-ocean portion of the carbon geochemical cycle in balance. The atmosphere-ocean carbon deficit requires replenishment of 6??1012 mol CO2/yr, and places an upper limit on the output of carbon dioxide from volcanoes. The CO2 output of the global mid-oceanic ridge system is ca. 0.7??1012 mol/yr, thus supplying only a fraction of the amount needed to balance the carbon deficit. The carbon dioxide flux from subaerial volcanoes is poorly known, but it appears to be at least as large as the mid-oceanic ridge flux. Much (perhaps most) of the CO2 emitted from volcanoes is degassed noneruptively. This mode of degassing may lead to impacts on the environment and biosphere that are fundamentally different in character from those envisioned in published scenarios, which are based on the assumption that CO2 degassing occurs predominantly by eruptive processes. Although the flux of carbon dioxide from volcanoes is poorly constrained at present, it is clearly two orders of magnitude lower than the anthropogenic output of CO2.

  1. Source-related variables for the description of the oceanic carbon system

    NASA Astrophysics Data System (ADS)

    Walin, G.; Hieronymus, J.; Nycander, J.

    2014-09-01

    oceanic carbon system is commonly described in terms of the two state variables total carbon, DIC, and alkalinity, Alk. Here we suggest the use of alternative source adapted state variables, Acidic Carbon, AC and Basic Carbon, BC, defined by and related to (DIC, Alk) with a simple linear transformation. (AC, BC) can be interpreted as representing respectively the supply to the system of carbon dioxide and dissolved carbonate, keeping in mind that supply of hydrogen ions acts to transform from basic carbon to acidic carbon. Accordingly these variables tell us how much carbon dioxide or dissolved carbonate we actually have in the water, despite the fact that the major part of the carbon resides in bicarbonate ions. We claim that using these source-related variables as a compliment to the traditional variables, offers a number of advantages in the formulation of continuity equations, as well as in the interpretation of observations and modeling results. The traditional definition of alkalinity is related to a measuring procedure rather than to the supply of material to the system. Here we demonstrate that alkalinity, though defined in the traditional way, may be interpreted in terms of sources and sinks acting on the system. In the case of ocean water this amounts to twice the supply of dissolved carbonate minus the net supply of free hydrogen ions. We argue that this interpretation is a useful complement to the traditional definition. Every process that affects the state of the carbon system may be quantified in terms of supply of carbon dioxide, Fa, carbonate ions, Fb, or hydrogen ions, E.

  2. Has Clinton made externalities extraneous

    SciTech Connect

    Haites, E.

    1993-08-01

    Over the past several years state utility regulators have become increasingly concerned with the environmental externalities associated with electricity generation. Currently, 26 states have requirements in place, although these vary considerably in scope and complexity. The vast majority apply only to the selection of new resources; the most detailed specify a monetary value for each discharge to the environment. Regulatory concern with environmental externalities stems from the desire to minimize the cost of electricity service to society. Externalities requirements focus on the residual discharges after environmental regulations are complied with. Ignoring externalities leads to inefficient use of resources and environmental damage beyond with may be called a [open quotes]socially optimal[close quotes] level of pollution. Adjusting to the cost options for environmental externalities should lead utilities to select a combination of resources that is closer to the socially optimal mix. President Bill Clinton's recent announcement that the United States will limit its emissions of carbon dioxide (CO[sub 2]) to 1990 levels by 2000 may make externalities regulation superfluous. National limits on sulfur dioxide (SO[sub 2]), nitrogen oxide (NO[sub x]), and CO[sub 2] emissions by utilities will likely be in effect by 2000. It will not be possible to comply with emissions limits solely through changes to the mix of resource additions, even though consideration of environmental externalities in resource addition decisions can reduce incremental emissions. Other strategies to reduce the emissions of existing generating stations, as well as new sources, will be needed.

  3. Effect of initial carbon sources on the performance of microbial fuel cells containing Proteus vulgaris.

    PubMed

    Kim, N; Choi, Y; Jung, S; Kim, S

    2000-10-05

    Mediator-coupled microbial fuel cells containing Proteus vulgaris were constructed and the cell performance was tested. Fuel cell efficiency depended on the carbon source in the initial medium of the microorganism. Maltose and trehalose were not utilized substantially by P. vulgaris; however, their presence in the initial medium resulted in enhanced cell performance. In particular, galactose showed 63% coulombic efficiency in a biofuel cell after P. vulgaris was cultured in a trehalose-containing medium. This work demonstrates that optimum utilization of carbon sources by microorganisms, which leads to the maximization of fuel cell performance, is possible simply by adjusting initial carbon sources.

  4. Artificial carbon dioxide source to attract lesser cornstalk borer (Lepidoptera: Pyralidae) larvae.

    PubMed

    Huang, X; Mack, T P

    2001-08-01

    Different combinations of urea, urease (in jack bean meal, Canavalia DC.), and water were tested as carbon dioxide sources to attract larvae of lesser cornstalk borer, Elasmopalus lignosellus (Zeller), by using olfactory bioassays with an olfactometer and infrared gas analysis. A combination of urea, jack bean meal, and water was necessary to release a high level of carbon dioxide to attract the larvae. Different proportions of the three ingredients had different carbon dioxide release rates and exhibited different levels of attraction to the larvae. When carbon dioxide concentration was too high, attractiveness declined. Combinations with different amounts of water remained attractive for a period of up to 3 d, depending on the moisture of the samples. When Zonolite was used to simulate the soil conditions in the olfactometer, significantly more larvae located the area near the artificial carbon dioxide sources compared with the control. When combined with the artificial carbon dioxide sources, three insecticides (Lorsban, Temik, and Force) did not obviously affect the release rates of carbon dioxide, and more larvae were attracted to samples with the carbon dioxide source than to the samples without carbon dioxide.

  5. Distribution and Sources of Black Carbon in the Arctic

    NASA Astrophysics Data System (ADS)

    Qi, Ling

    The Arctic is warming at twice the global rate over recent decades. To slow down this warming trend, there is growing interest in reducing the impact from short-lived climate forcers, such as black carbon (BC), because the benefits of mitigation are seen more quickly relative to CO2 reduction. To propose efficient mitigation policies, it is imperative to improve our understanding of BC distribution in the Arctic and to identify the sources. In this dissertation, we investigate the sensitivity of BC in the Arctic, including BC concentrations in snow (BCsnow) and BC concentrations in air (BCair), to emissions, dry deposition and wet scavenging using a global 3-D chemical transport model (CTM) GEOS-Chem. By including flaring emissions, estimating dry deposition velocity using resistance-in-series method, and including Wegener-Bergeron-Findeisen (WBF) in wet scavenging, simulated BCsnow in the eight Arctic sub-regions agree with the observations within a factor of two, and simulated BCair fall within the uncertainty range of observations. Specifically, we find that natural gas flaring emissions in Western Extreme North of Russia (WENR) strongly enhance BCsnow (by up to ?50%) and BCair (by 20-32%) during snow season in the so-called 'Arctic front', but has negligible impact on BC in the free troposphere. The updated dry deposition velocity over snow and ice is much larger than those used in most of global CTMs and agrees better with observation. The resulting BCsnow changes marginally because of the offsetting of higher dry and lower wet deposition fluxes. In contrast, surface BCair decreases strongly due to the faster dry deposition (by 27-68%). WBF occurs when the environmental vapor pressure is in between the saturation vapor pressure of ice crystals and water drops in mixed-phase clouds. As a result, water drops evaporate and releases BC particles in them back into the interstitial air. In most CTMs, WBF is either missing or represented by a uniform and low BC

  6. Black carbon and carbon monoxide over Bay of Bengal during W_ICARB: Source characteristics

    NASA Astrophysics Data System (ADS)

    Girach, I. A.; Nair, Vijayakumar S.; Babu, S. Suresh; Nair, Prabha R.

    2014-09-01

    The ship borne measurements of near-surface black carbon (BC) and carbon monoxide (CO) were carried out over Bay of Bengal (BoB) during the winter period of 2009 under W_ICARB, the second phase of ‘Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB)'. The CO mixing ratio and BC mass concentration varied in the ranges of 80-480 ppbv and 75-10,000 ng m-3, respectively over this marine region. The BC and CO showed similar variations over northern BoB where airmass from Indo-Gangetic Plain (IGP) region prevailed during the observations period leading to a very strong positive correlation. The association of BC and CO was poor over the eastern and southern part of BoB could be due to the removal of BC aerosols by rain and/or processes of dilution and mixing while transported over to BoB. The highest value of CO observed over eastern BoB was partially due to biomass burning over East Asia. The BC/CO ratio for IGP airmass found to be 20.3 ng m-3 ppb-1 and ∼16 ng m-3 ppb-1 during winter and pre-monsoon, respectively which indicate the role of biomass burning as the source of BC over the region. Based on the emission flux of CO from various inventories and observed BC/CO ratios during pre-monsoon and winter, the BC emission for India is estimated to be in the range of 0.78-1.23 Tg year-1. The analysis of scavenging of BC revealed the loss rate of BC due to relative humidity 0.39 ± 0.08 ng m-3 ppb-1 RH (%)-1 over northern BoB and 0.53 ± 0.04 ng m-3 ppb-1 RH (%)-1 over the southern-BoB during winter.

  7. Investigation of organic carbon transformation in soils of dominant dissolved organic carbon source zones

    NASA Astrophysics Data System (ADS)

    Pissarello, Anna; Miltner, Anja; Oosterwoud, Marieke; Fleckenstein, Jan; Kästner, Matthias

    2014-05-01

    Over the past 20 years both a decrease in soil organic matter (SOM) and an increase in the dissolved organic carbon (DOC) concentrations in surface water bodies, including drinking water reservoirs, have been recorded in the northern hemisphere. This development has severe consequences for soil fertility and for drinking water purification. As both processes occur simultaneously, we assume that microbial SOM degradation, which transforms SOM into CO2 and DOC, is a possible source of the additional DOC in the surface water. In addition we speculate that both processes are initially triggered by physical mechanisms, resulting in a modification of the organic matter solubility equilibria and thus in higher SOM availability and DOC mobilization. The general hypothesis of the study is therefore that SOM loss and DOC increase are combined consequences of enhanced microbial degradation of SOM and that this is a result of climate variations and global change, e.g. the increase of the temperature, the alteration of the water regime (i.e. increase of the frequency of drying and rewetting cycles and a higher number of heavy rain events), but also the decrease of the atmospheric acid deposition resulting in an increase of soil pH values. The general goal of the study is the identification of the dominant processes and controlling factors involved in soil microbial carbon turnover and mobilization of DOC in soils from catchment areas that contribute DOC to the receiving waters and the downstream Rappbode reservoir, which showed a pronounced increase in DOC concentration in recent years. This reservoir is the source of drinking water for about one million people in northern Germany. Preliminary screening experiments, consisting of 65-day soil batch incubation experiments, have been conducted in order to select the parameters (and the parameter ranges) of relevance for further in-depth experiments. During the experiments, different soil systems were exposed to different

  8. Source apportionment of PM10, organic carbon and elemental carbon at Swiss sites: an intercomparison of different approaches.

    PubMed

    Gianini, M F D; Piot, C; Herich, H; Besombes, J-L; Jaffrezo, J-L; Hueglin, C

    2013-06-01

    In this study, the results of source apportionment of particulate matter (PM10), organic carbon (OC), and elemental carbon (EC) - as obtained through different approaches at different types of sites (urban background, urban roadside, and two rural sites in Switzerland) - are compared. The methods included in this intercomparison are positive matrix factorisation modelling (PMF, applied to chemical composition data including trace elements, inorganic ions, OC, and EC), molecular marker chemical mass balance modelling (MM-CMB), and the aethalometer model (AeM). At all sites, the agreement of the obtained source contributions was reasonable for OC, EC, and PM10. Based on an annual average, and at most of the considered sites, secondary organic carbon (SOC) is the component with the largest contribution to total OC; the most important primary source of OC is wood combustion, followed by road traffic. Secondary aerosols predominate in PM10. All considered techniques identified road traffic as the dominant source of EC, while wood combustion emissions are of minor importance for this constituent. The intercomparison of different source apportionment approaches is helpful to identify the strengths and the weaknesses of the different methods. Application of PMF has limitations when source emissions have a strong temporal correlation, or when meteorology has a strong impact on PM variability. In these cases, the use of PMF can result in mixed source profiles and consequently in the under- or overestimation of the real-world sources. The application of CMB models can be hampered by the unavailability of source profiles and the non-representativeness of the available profiles for local source emissions. This study also underlines that chemical transformations of molecular markers in the atmosphere can lead to the underestimation of contributions from primary sources, in particular during the summer period or when emission sources are far away from the receptor sites.

  9. Excess cell mass as an internal carbon source for biological denitrification.

    PubMed

    Biradar, Prashant M; Roy, S B; D'Souza, S F; Pandit, A B

    2010-03-01

    Aim of the present work was to examine whether the SCOD (soluble chemical oxygen demand) released after the physical disruption of excess activated sludge can be used as an alternative carbon source for biological denitrification. In the first stage of research, we investigated the potential use of energy efficient hydrodynamic cavitation (HC) technique for the disruption of activated sludge. In a comparative study between ultrasonic cavitation (UC) and HC, it was observed that UC needs five times more energy than that of HC to release the same amount of SCOD. In the second stage of the experimental study, SCOD was successfully used as an alternative carbon source (alternative to sodium acetate) for biological denitrification. The critical weight ratio (SCOD/NO(3)-N) of seven ensured 100% removal of nitrate. Nitrate removal kinetics indicated that denitrification with SCOD as a carbon source gives higher specific denitrification rate (by approximately 200%) as compared to conventional carbon source (sodium acetate).

  10. [Kinetic simulation of enhanced biological phosphorus removal with fermentation broth as carbon source].

    PubMed

    Zhang, Chao; Chen, Yin-Guang

    2013-07-01

    As a high-quality carbon source, fermentation broth could promote the phosphorus removal efficiency in enhanced biological phosphorus removal (EBPR). The transformation of substrates in EBPR fed with fermentation broth was well simulated using the modified activated sludge model No. 2 (ASM2) based on the carbon source metabolism. When fermentation broth was used as the sole carbon source, it was found that heterotrophic bacteria acted as a promoter rather than a competitor to the phosphorus accumulating organisms (PAO). When fermentation broth was used as a supplementary carbon source of real municipal wastewater, the wastewater composition was optimized for PAO growth; and the PAO concentration, which was increased by 3.3 times compared to that in EBPR fed with solely real municipal wastewater, accounting for about 40% of the total biomass in the reactor.

  11. Review: role of carbon sources for in vitro plant growth and development.

    PubMed

    Yaseen, Mehwish; Ahmad, Touqeer; Sablok, Gaurav; Standardi, Alvaro; Hafiz, Ishfaq Ahmad

    2013-04-01

    In vitro plant cells, tissues and organ cultures are not fully autotrophic establishing a need for carbohydrates in culture media to maintain the osmotic potential, as well as to serve as energy and carbon sources for developmental processes including shoot proliferation, root induction as well as emission, embryogenesis and organogenesis, which are highly energy demanding developmental processes in plant biology. A variety of carbon sources (both reducing and non-reducing) are used in culture media depending upon genotypes and specific stages of growth. However, sucrose is most widely used as a major transport-sugar in the phloem sap of many plants. In micropropagation systems, morphogenetic potential of plant tissues can greatly be manipulated by varying type and concentration of carbon sources. The present article reviews the past and current findings on carbon sources and their sustainable utilization for in vitro plant tissue culture to achieve better growth rate and development.

  12. Quasi-steady carbon plasma source for neutral beam injector

    SciTech Connect

    Koguchi, H. Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y.

    2014-02-15

    Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

  13. Quasi-steady carbon plasma source for neutral beam injector

    NASA Astrophysics Data System (ADS)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y.

    2014-02-01

    Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ˜3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

  14. Quasi-steady carbon plasma source for neutral beam injector.

    PubMed

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2014-02-01

    Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

  15. Laboratory Evaluation of Selected Ways for Determining Black Carbon Source Emissions

    EPA Science Inventory

    A number of studies have been conducted which compare various methods for the determination of black carbon in the atmosphere. Relatively little attention has been paid, however, to similar measurements of black carbon from different types of emission sources. Of particular int...

  16. Using liquid waste streams as the moisture source during the hydrothermal carbonization of municipal solid wastes.

    PubMed

    Li, Liang; Hale, McKenzie; Olsen, Petra; Berge, Nicole D

    2014-11-01

    Hydrothermal carbonization (HTC) is a thermal conversion process that can be an environmentally beneficial approach for the conversion of municipal solid wastes to value-added products. The influence of using activated sludge and landfill leachate as initial moisture sources during the carbonization of paper, food waste and yard waste over time at 250°C was evaluated. Results from batch experiments indicate that the use of activated sludge and landfill leachate are acceptable alternative supplemental liquid sources, ultimately imparting minimal impact on carbonization product characteristics and yields. Regression results indicate that the initial carbon content of the feedstock is more influential than any of the characteristics of the initial liquid source and is statistically significant when describing the relationship associated with all evaluated carbonization products. Initial liquid-phase characteristics are only statistically significant when describing the solids energy content and the mass of carbon in the gas-phase. The use of these alternative liquid sources has the potential to greatly increase the sustainability of the carbonization process. A life cycle assessment is required to quantify the benefits associated with using these alternative liquid sources.

  17. Contribution of different carbon sources to isoprene biosynthesis in poplar leaves.

    PubMed

    Schnitzler, Jörg-Peter; Graus, Martin; Kreuzwieser, Jürgen; Heizmann, Ulrike; Rennenberg, Heinz; Wisthaler, Armin; Hansel, Armin

    2004-05-01

    This study was performed to test if alternative carbon sources besides recently photosynthetically fixed CO2 are used for isoprene formation in the leaves of young poplar (Populus x canescens) trees. In a 13CO2 atmosphere under steady state conditions, only about 75% of isoprene became 13C labeled within minutes. A considerable part of the unlabeled carbon may be derived from xylem transported carbohydrates, as may be shown by feeding leaves with [U-13C]Glc. As a consequence of this treatment approximately 8% to 10% of the carbon emitted as isoprene was 13C labeled. In order to identify further carbon sources, poplar leaves were depleted of leaf internal carbon pools and the carbon pools were refilled with 13C labeled carbon by exposure to 13CO2. Results from this treatment showed that about 30% of isoprene carbon became 13C labeled, clearly suggesting that, in addition to xylem transported carbon and CO2, leaf internal carbon pools, e.g. starch, are used for isoprene formation. This use was even increased when net assimilation was reduced, for example by abscisic acid application. The data provide clear evidence of a dynamic exchange of carbon between different cellular precursors for isoprene biosynthesis, and an increasing importance of these alternative carbon pools under conditions of limited photosynthesis. Feeding [1,2-13C]Glc and [3-13C]Glc to leaves via the xylem suggested that alternative carbon sources are probably derived from cytosolic pyruvate/phosphoenolpyruvate equivalents and incorporated into isoprene according to the predicted cleavage of the 3-C position of pyruvate during the initial step of the plastidic deoxyxylulose-5-phosphate pathway.

  18. Thermoplastic-based conductive composites containing multi-wall carbon nanotubes aligned under the application of external electric fields

    NASA Astrophysics Data System (ADS)

    Osazuwa, Osayuki

    The objective of this thesis is to prepare thermoplastic/multi-wall carbon nanotubes (MWCNTs) and to apply external alternating current (AC) electric fields to achieve enhanced conductivity and dielectric properties. The first part of the thesis focuses on preparing polyolefin-based composites containing welldispersed MWCNTs. MWCNTs are functionalized with a hyperbranched polyethylene (HBPE) using a non-covalent, non-specific functionalization approach and melt compounded with an ethylene-octene copolymer (EOC) matrix. The improved filler dispersion in the functionalized EOC/MWCNT composite results in higher elongation at break compared to the non-functionalized composite. However, the electrical percolation threshold and the ultimate conductivity of the composites are not affected considerably, suggesting that this functionalization approach leaves the inherent properties of the nanotubes intact. EOC/HBPE-functionalized MWCNT composites are further subjected to external AC electric fields (35 -- 212 kV/m), which induce the formation of aligned columnar structures, as evidenced by Scanning Electron Microscopy. Experimentally acquired resistivity data are used to derive correlations between the characteristic insulator-to-conductor transition times of the composites and the electric field strength (E), polymer viscosity (eta) and MWCNT volume fraction (φ). A criterion for the selection of (eta, E, φ) conditions that enable MWCNT assembly under an electric field controlled regime (minimal Brownian motion-driven aggregation effects) is developed. The dielectric properties of the solidified aligned EOC/MWCNT composites are further studied using dielectric spectroscopy. Annealing of the composites at 160 °C results in the formation of interconnected structures, whereas electrification, using AC field of 71 and 212 kV/m induces the formation of aligned columnar structures. The electrified and annealed composites have increased real and imaginary permittivity compared

  19. Phase Space Generation for Proton and Carbon Ion Beams for External Users’ Applications at the Heidelberg Ion Therapy Center

    PubMed Central

    Tessonnier, Thomas; Marcelos, Tiago; Mairani, Andrea; Brons, Stephan; Parodi, Katia

    2016-01-01

    In the field of radiation therapy, accurate and robust dose calculation is required. For this purpose, precise modeling of the irradiation system and reliable computational platforms are needed. At the Heidelberg Ion Therapy Center (HIT), the beamline has been already modeled in the FLUKA Monte Carlo (MC) code. However, this model was kept confidential for disclosure reasons and was not available for any external team. The main goal of this study was to create efficiently phase space (PS) files for proton and carbon ion beams, for all energies and foci available at HIT. PSs are representing the characteristics of each particle recorded (charge, mass, energy, coordinates, direction cosines, generation) at a certain position along the beam path. In order to achieve this goal, keeping a reasonable data size but maintaining the requested accuracy for the calculation, we developed a new approach of beam PS generation with the MC code FLUKA. The generated PSs were obtained using an infinitely narrow beam and recording the desired quantities after the last element of the beamline, with a discrimination of primaries or secondaries. In this way, a unique PS can be used for each energy to accommodate the different foci by combining the narrow-beam scenario with a random sampling of its theoretical Gaussian beam in vacuum. PS can also reproduce the different patterns from the delivery system, when properly combined with the beam scanning information. MC simulations using PS have been compared to simulations, including the full beamline geometry and have been found in very good agreement for several cases (depth dose distributions, lateral dose profiles), with relative dose differences below 0.5%. This approach has also been compared with measured data of ion beams with different energies and foci, resulting in a very satisfactory agreement. Hence, the proposed approach was able to fulfill the different requirements and has demonstrated its capability for application to

  20. Optimization of an Atmospheric Carbon Source for Extremophile Cyanobacteria

    NASA Astrophysics Data System (ADS)

    Beaubien, Courtney

    This thesis examines the use of the moisture swing resin materials employed at the Center for Negative Carbon Emissions (CNCE) in order to provide carbon dioxide from ambient air to photobioreactors containing extremophile cyanobacteria cultured at the Arizona Center for Algae Technology and Innovation (AzCATI). For this purpose, a carbon dioxide feeding device was designed, built, and tested. The results indicate how much resin should be used with a given volume of algae medium: approximately 500 grams of resin can feed 1% CO2 at about three liters per minute to a ten liter medium of the Galdieria sulphuraria 5587.1 strain for one hour (equivalent to about 0.1 grams of carbon dioxide per hour per seven grams of algae). Using the resin device, the algae grew within their normal growth range: 0.096 grams of ash-free dry weight per liter over a six hour period. Future applications in which the resin-to-algae process can be utilized are discussed.

  1. Deposition of superhard amorphous carbon films by pulsed arc sources

    SciTech Connect

    Scheibe, H.J.; Schultrich, B.; Ziegele, H.; Siemroth, P.

    1996-12-31

    Hydrogen-free amorphous carbon films with hardness comparable to crystalline superhard materials have been deposited by special Pulsed arc techniques. By the combination of very high hardness, low adhesion and high smoothness, these films show superior behaviour in wear and glide applications. The influence of plasma and deposition conditions on these film properties and the choice of optimum conditions are discussed.

  2. Detection of coliforms in drinking water using skin patches: a rapid, reliable method that does not require an external energy source.

    PubMed

    Nam, Sehee; Kim, Min-jeong; Park, MinSun; Kim, Nuri; Lee, Yu-jin; Lee, Gyu-Cheol

    2014-02-01

    The detection of coliforms requires incubation in a laboratory, generally powered using electricity. In many parts of the developing world, however, external energy sources such as electricity are not readily available. To develop a fast, reliable method for detecting coliforms in water without an external energy source, we assessed the efficacy of six test kits for the identification of coliforms in water samples. To assess the possibility of using body temperature as the sole source of heat for incubation, bacterial samples were then mixed with the enzymatic test kit reagent and attached to the human body surface using a patch system. The patches were attached to the bodies of volunteers for 24 hours and the practicality and accuracy of the patches were assessed. Coliforms were detected within 24 hours in all patches. This innovation will facilitate the testing of water quality by researchers and by economically disadvantaged people without electricity.

  3. Glucose becomes one of the worst carbon sources for E.coli on poor nitrogen sources due to suboptimal levels of cAMP.

    PubMed

    Bren, Anat; Park, Junyoung O; Towbin, Benjamin D; Dekel, Erez; Rabinowitz, Joshua D; Alon, Uri

    2016-04-25

    In most conditions, glucose is the best carbon source for E. coli: it provides faster growth than other sugars, and is consumed first in sugar mixtures. Here we identify conditions in which E. coli strains grow slower on glucose than on other sugars, namely when a single amino acid (arginine, glutamate, or proline) is the sole nitrogen source. In sugar mixtures with these nitrogen sources, E. coli still consumes glucose first, but grows faster rather than slower after exhausting glucose, generating a reversed diauxic shift. We trace this counterintuitive behavior to a metabolic imbalance: levels of TCA-cycle metabolites including α-ketoglutarate are high, and levels of the key regulatory molecule cAMP are low. Growth rates were increased by experimentally increasing cAMP levels, either by adding external cAMP, by genetically perturbing the cAMP circuit or by inhibition of glucose uptake. Thus, the cAMP control circuitry seems to have a 'bug' that leads to slow growth under what may be an environmentally rare condition.

  4. Glucose becomes one of the worst carbon sources for E.coli on poor nitrogen sources due to suboptimal levels of cAMP

    PubMed Central

    Bren, Anat; Park, Junyoung O.; Towbin, Benjamin D.; Dekel, Erez; Rabinowitz, Joshua D.; Alon, Uri

    2016-01-01

    In most conditions, glucose is the best carbon source for E. coli: it provides faster growth than other sugars, and is consumed first in sugar mixtures. Here we identify conditions in which E. coli strains grow slower on glucose than on other sugars, namely when a single amino acid (arginine, glutamate, or proline) is the sole nitrogen source. In sugar mixtures with these nitrogen sources, E. coli still consumes glucose first, but grows faster rather than slower after exhausting glucose, generating a reversed diauxic shift. We trace this counterintuitive behavior to a metabolic imbalance: levels of TCA-cycle metabolites including α-ketoglutarate are high, and levels of the key regulatory molecule cAMP are low. Growth rates were increased by experimentally increasing cAMP levels, either by adding external cAMP, by genetically perturbing the cAMP circuit or by inhibition of glucose uptake. Thus, the cAMP control circuitry seems to have a ‘bug’ that leads to slow growth under what may be an environmentally rare condition. PMID:27109914

  5. Development of a stationary carbon emission inventory for Shanghai using pollution source census data

    NASA Astrophysics Data System (ADS)

    Li, Xianzhe; Jiang, Ping; Zhang, Yan; Ma, Weichun

    2016-12-01

    This study utilizes 521,631 activity data points from the 2007 Shanghai Pollution Source Census to compile a stationary carbon emission inventory for Shanghai. The inventory generated from our dataset shows that a large portion of Shanghai's total energy use consists of coal-oriented energy consumption. The electricity and heat production industries, iron and steel mills, and the petroleum refining industry are the main carbon emitters. In addition, most of these industries are located in Baoshan District, which is Shanghai's largest contributor of carbon emissions. Policy makers can use the enterpriselevel carbon emission inventory and the method designed in this study to construct sound carbon emission reduction policies. The carbon trading scheme to be established in Shanghai based on the developed carbon inventory is also introduced in this paper with the aim of promoting the monitoring, reporting and verification of carbon trading. Moreover, we believe that it might be useful to consider the participation of industries, such as those for food processing, beverage, and tobacco, in Shanghai's carbon trading scheme. Based on the results contained herein, we recommend establishing a comprehensive carbon emission inventory by inputting data from the pollution source census used in this study.

  6. Development of a stationary carbon emission inventory for Shanghai using pollution source census data

    NASA Astrophysics Data System (ADS)

    Li, Xianzhe; Jiang, Ping; Zhang, Yan; Ma, Weichun

    2016-03-01

    This study utilizes 521,631 activity data points from the 2007 Shanghai Pollution Source Census to compile a stationary carbon emission inventory for Shanghai. The inventory generated from our dataset shows that a large portion of Shanghai's total energy use consists of coal-oriented energy consumption. The electricity and heat production industries, iron and steel mills, and the petroleum refining industry are the main carbon emitters. In addition, most of these industries are located in Baoshan District, which is Shanghai's largest contributor of carbon emissions. Policy makers can use the enterpriselevel carbon emission inventory and the method designed in this study to construct sound carbon emission reduction policies. The carbon trading scheme to be established in Shanghai based on the developed carbon inventory is also introduced in this paper with the aim of promoting the monitoring, reporting and verification of carbon trading. Moreover, we believe that it might be useful to consider the participation of industries, such as those for food processing, beverage, and tobacco, in Shanghai's carbon trading scheme. Based on the results contained herein, we recommend establishing a comprehensive carbon emission inventory by inputting data from the pollution source census used in this study.

  7. Land Use Affects Carbon Sources to the Pelagic Food Web in a Small Boreal Lake

    PubMed Central

    Rinta, Päivi; van Hardenbroek, Maarten; Jones, Roger I.; Kankaala, Paula; Rey, Fabian; Szidat, Sönke; Wooller, Matthew J.; Heiri, Oliver

    2016-01-01

    Small humic forest lakes often have high contributions of methane-derived carbon in their food webs but little is known about the temporal stability of this carbon pathway and how it responds to environmental changes on longer time scales. We reconstructed past variations in the contribution of methanogenic carbon in the pelagic food web of a small boreal lake in Finland by analyzing the stable carbon isotopic composition (δ13C values) of chitinous fossils of planktivorous invertebrates in sediments from the lake. The δ13C values of zooplankton remains show several marked shifts (approx. 10 ‰), consistent with changes in the proportional contribution of carbon from methane-oxidizing bacteria in zooplankton diets. The results indicate that the lake only recently (1950s) obtained its present state with a high contribution of methanogenic carbon to the pelagic food web. A comparison with historical and palaeobotanical evidence indicates that this most recent shift coincided with agricultural land-use changes and forestation of the lake catchment and implies that earlier shifts may also have been related to changes in forest and land use. Our study demonstrates the sensitivity of the carbon cycle in small forest lakes to external forcing and that the effects of past changes in local land use on lacustrine carbon cycling have to be taken into account when defining environmental and ecological reference conditions in boreal headwater lakes. PMID:27487044

  8. Estimating the seasonal carbon source-sink geography of a natural, steady-state terrestrial biosphere

    NASA Technical Reports Server (NTRS)

    Box, Elgene O.

    1988-01-01

    The estimation of the seasonal dynamics of biospheric-carbon sources and sinks to be used as an input to global atmospheric CO2 studies and models is discussed. An ecological biosphere model is given and the advantages of the model are examined. Monthly maps of estimated biospheric carbon source and sink regions and estimates of total carbon fluxes are presented for an equilibrium terrestrial biosphere. The results are compared with those from other models. It is suggested that, despite maximum variations of atmospheric CO2 in boreal latitudes, the enormous contributions of tropical wet-dry regions to global atmospheric CO2 seasonality can not be ignored.

  9. Synthesis and characterization of WC-Co nanosized composite powders with in situ carbon and gas carbon sources

    NASA Astrophysics Data System (ADS)

    Yang, Qiumin; Yang, Jiangao; Yang, Hailin; Su, Wei; Ruan, Jianming

    2016-07-01

    This study presented nanosized WC-Co composite powders synthesized using a one-step reduction-carbonization process with a combination of CH4/H2 as a gas carbon source and soluble starch as an in situ carbon source. The results of carbon analysis and X-ray diffraction revealed that WC-Co nanocomposite powders with a pure WC and Co phase could be obtained at 1100 °C after 0.5 h. A higher gas flow ratio of CH4/H2 during the reduction-carbonization process led to a higher total carbon content of the sample. A field emission scanning electron microscope confirmed that the particles in the WC-6 wt% Co composite powders had the lowest average size of 43 nm with equiaxed shapes. A sintering neck was observed in the WC-3 wt% Co composite powders whereas faceted particles were found in the WC-12 wt% Co composite powders. Moreover, this method has advantages of simple processing, rapid synthesis and good applicability in potential industry application.

  10. Carbon Sources to Authigenic Carbonate Rock at Chemosynthetic Communities: Lower Slope of the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Sassen, R.; Jung, W.; Zhang, C.; Defreitas, D. A.

    2004-12-01

    Flux of biogenic methane, crude oil and associated hydrocarbon gases occurs from the deep subsurface to the seafloor, water column, and atmosphere of the Gulf of Mexico slope. Chemosynthetic communities occur at sites of relatively high gas flux, frequently with gas hydrate, but always with authigenic carbonate rock \\(ACR\\). ACR contains carbonate carbon derived from microbial hydrocarbon oxidation that geologically sequesters much fossil carbon, perturbing the carbon cycle. ACR was collected using the ALVIN from sites with chemosynthetic communities in Alaminos Canyon, Atwater Valley, and the Florida Escarpment areas at water depths as much as 3.3 km. Bulk δ 13C was measured and carbonate petrology used to identify carbonate cements, normal marine carbonate, and non-carbonate components such as metal oxides and sulfides. ACR is depleted in 13C. However, the δ 13C of major hydrocarbon types is typically more depleted in 13C than the associated ACR. For example, the mean δ 13C of biogenic methane seeps in the Gulf slope is -74.0\\permil PDB but the lightest bulk ACR measured in the study area is -46.6\\permil PDB. Carbonate cements from hydrocarbon oxidation are shown to enclose skeletal remains of chemosynthetic fauna such as mussels, clams, as well as other fauna characterized by normal marine carbonate \\(\\sim 0\\permil PDB\\). The best explanation of why the δ 13C of ACR does not closely correspond to that of the hydrocarbon starting products is that normal marine carbon dilutes the δ 13C from hydrocarbon oxidation and thus affects the bulk isotopic properties of ACR.

  11. The rate of iron corrosion for different organic carbon sources during biofilm formation.

    PubMed

    Park, S K; Choi, S C; Kim, Y K

    2007-01-01

    The effects of total organic carbon and biofilm on microbial corrosion were quantified using serum bottles in a 2 x 2 factorial design. Both organic carbon and biofilm bacteria had a significant effect on the iron corrosion rate, irrespective of the levels of the other variable (p = 0.05). There was no evidence of interaction between organic carbon and biofilm bacteria. Within the tested levels, the addition of exogenous organic carbon increased the corrosion rate by an average of 3.838 mg dm(-2) day(-1) (mdd), but the presence of biofilm bacteria decreased the rate by an average of 2.305 mdd. More iron was released from the coupon in response to organic carbon. Powder x-ray diffractometry indicated that the scales deposited on the corroded iron surface consisted primarily of lepidocrocite (gamma-FeOOH), magnetite (Fe3O4) and hematite (alpha-Fe203). Corrosion rates by different organic carbon sources, i.e. acetate, glucose and humic substances, were compared using an annular biofilm reactor. One-way ANOVA suggested that the effect of each carbon source on corrosion was not the same, with the iron corrosion rate highest for glucose, followed by acetate, humic substances and the control. Magnetite was a major constituent of the corrosion products scraped from iron slides. Examination of community-level physiological profile patterns on the biofilms indicated that acetate was a carbon source that could promote the metabolic and functional potentials of biofilm communities.

  12. Gas-solid carbonation as a possible source of carbonates in cold planetary environments

    NASA Astrophysics Data System (ADS)

    Garenne, A.; Montes-Hernandez, G.; Beck, P.; Schmitt, B.; Brissaud, O.; Pommerol, A.

    2013-02-01

    Carbonates are abundant sedimentary minerals at the surface and sub-surface of the Earth and they have been proposed as tracers of liquid water in extraterrestrial environments. Their formation mechanism is since generally associated with aqueous alteration processes. Recently, carbonate minerals have been discovered on Mars' surface by different orbitals or rover missions. In particular, the phoenix mission has measured from 1% to 5% of calcium carbonate (calcite type) within the soil (Smith et al., 2009). These occurrences have been reported in area where the relative humidity is significantly high (Boynton et al., 2009). The small concentration of carbonates suggests an alternative process on mineral grain surfaces (as suggested by Shaheen et al., 2010) than carbonation in aqueous conditions. Such an observation could rather point toward a possible formation mechanism by dust-gas reaction under current Martian conditions. To understand the mechanism of carbonate formation under conditions relevant to current Martian atmosphere and surface, we designed an experimental setup consisting of an infrared microscope coupled to a cryogenic reaction cell (IR-CryoCell setup). Three different mineral precursors of carbonates (Ca and Mg hydroxides, and a hydrated Ca silicate formed from Ca2SiO4), low temperature (from -10 to +30 °C), and reduced CO2 pressure (from 100 to 2000 mbar) were utilized to investigate the mechanism of gas-solid carbonation at mineral surfaces. These mineral materials are crucial precursors to form Ca and Mg carbonates in humid environments (0%carbonation process for Ca hydroxide and hydrated Ca silicate. Conversely, only a moderate carbonation is observed for the Mg hydroxide. These results suggest that gas-solid carbonation process or carbonate formation at the dust-water ice-CO2 interfaces could be a currently active Mars' surface

  13. Subsurface Intertidal Microbes: A Cryptic Source Of Organic Carbon For Beach Ecosystems

    NASA Technical Reports Server (NTRS)

    Rothschild, Lynn J.; Giver, Lorraine J.; Alvarez, Teresa (Technical Monitor)

    1994-01-01

    Some freshwater, marine or hotspring beaches have no visible source of primary production, yet beneath the surface is an interstitial photosynthetic microbial community. To assess the significance of this source of organic carbon, we measured in situ carbon fixation rates in an intertidal marine beach through a diurnal cycle. Gross fixation for a transect (99 x 1 m) perpendicular to the shore was approx. 4041 mg C fixed/ day, or approx. 41 mg C fixed/ sq m day. In contrast, an adjacent well-established cyanobacterial (Lyngbya) mat was approx. 12 x as productive (approx. 490 mg C fixed/sq m day). Thus, subsurface sand mats may be an overlooked, yet important, endogenous source of organic carbon for intertidal ecosystems, as well as a sink in the global carbon cycle.

  14. Energy Deposition in the Body from External Sources to Chemically Trigger Cellular Responses in Desired Localized Regions

    NASA Astrophysics Data System (ADS)

    Ibsen, Stuart Duncan

    One of the major challenges of modern chemotherapy is to deliver a therapeutic dose of active drug to the tumor tissue without causing systemic exposure. The realization of this goal could considerably reduce the negative side effects experienced by patients. The work conducted in this thesis looks at two different approaches to trigger drug activation with the use of external energy sources. This avoids the challenges of relying solely on biochemical and environmental differences as triggers. The two triggers used were low intensity focused ultrasound and 365 nm light delivered with a custom designed needle UV LED fiber optic system. Both can be localized within the body to spatially highlight just the tumor tissue creating a stark differentiation between it and the healthy tissue. The 365nm light based delivery scheme developed here was the first demonstration of a photoactivatable doxorubicin (DOX) prodrug called DOX-PCB. DOX-PCB was shown to be 200 times less toxic than DOX and could be activated to a fully therapeutic form upon exposure to 365nm light. The pharmacokinetics showed a circulation half life comparable to that of DOX and stability against in vivo metabolic degradation. The 365 nm light was shown to adequately irradiate a centimeter of tumor tissue and cause localized activation. In vivo tumors exposed to the light had significantly higher doses of DOX than unexposed control tumors in the same individual. The second delivery scheme made use of focused ultrasound to activate echogenic drug delivery vehicles. These vehicles were the first demonstration of encapsulating microbubbles within liposomes. Specially designed optical equipment documented that the microbubble was ultrasound responsive. The microbubble was shown to violently cavitate and rupture the outer liposome membrane releasing the payload contents. The three dimensional localization of activation was demonstrated in tissue phantoms. The strengths of these two delivery schemes could

  15. How organic carbon derived from multiple sources contributes to carbon sequestration processes in a shallow coastal system?

    PubMed

    Watanabe, Kenta; Kuwae, Tomohiro

    2015-04-16

    Carbon captured by marine organisms helps sequester atmospheric CO2 , especially in shallow coastal ecosystems, where rates of primary production and burial of organic carbon (OC) from multiple sources are high. However, linkages between the dynamics of OC derived from multiple sources and carbon sequestration are poorly understood. We investigated the origin (terrestrial, phytobenthos derived, and phytoplankton derived) of particulate OC (POC) and dissolved OC (DOC) in the water column and sedimentary OC using elemental, isotopic, and optical signatures in Furen Lagoon, Japan. Based on these data analysis, we explored how OC from multiple sources contributes to sequestration via storage in sediments, water column sequestration, and air-sea CO2 exchanges, and analyzed how the contributions vary with salinity in a shallow seagrass meadow as well. The relative contribution of terrestrial POC in the water column decreased with increasing salinity, whereas autochthonous POC increased in the salinity range 10-30. Phytoplankton-derived POC dominated the water column POC (65-95%) within this salinity range; however, it was minor in the sediments (3-29%). In contrast, terrestrial and phytobenthos-derived POC were relatively minor contributors in the water column but were major contributors in the sediments (49-78% and 19-36%, respectively), indicating that terrestrial and phytobenthos-derived POC were selectively stored in the sediments. Autochthonous DOC, part of which can contribute to long-term carbon sequestration in the water column, accounted for >25% of the total water column DOC pool in the salinity range 15-30. Autochthonous OC production decreased the concentration of dissolved inorganic carbon in the water column and thereby contributed to atmospheric CO2 uptake, except in the low-salinity zone. Our results indicate that shallow coastal ecosystems function not only as transition zones between land and ocean but also as carbon sequestration filters. They function

  16. Soil Carbon Dynamics in a Shelterbelt in the Midwest: Sources and Spatial Variability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shelterbelt planting in cropland may sequester carbon (C), but sources and spatial variability have not been documented. This study was conducted to assess sources and spatial variation of soil organic C (SOC) in a 35-year-old shelterbelt, and in two adjacent cultivated fields (CF) in eastern Nebras...

  17. Carbon sources and dynamics in afforested and cultivated US corn belt soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Afforestation in degraded cropland can sequester atmospheric carbon (C), but soil organic C (SOC) sources in such ecosystems are not well-characterized. This study assessed SOC dynamics and sources in two 35-yr-old, coniferous afforestation sites (i.e., a forest plantation and a shelterbelt situated...

  18. Carbon sources and dynamics in afforested and cultivated corn belt soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Afforestation of degraded cropland can sequester atmospheric carbon (C), but soil organic C (SOC) sources in such ecosystems are not well-characterized. This study assessed SOC dynamics and sources in two 35-yr-old, coniferous afforestation sites [i.e., a forest plantation and a shelterbelt situated...

  19. A shift of thermokarst lakes from carbon sources to sinks during the Holocene epoch.

    PubMed

    Anthony, K M Walter; Zimov, S A; Grosse, G; Jones, M C; Anthony, P M; Chapin, F S; Finlay, J C; Mack, M C; Davydov, S; Frenzel, P; Frolking, S

    2014-07-24

    Thermokarst lakes formed across vast regions of Siberia and Alaska during the last deglaciation and are thought to be a net source of atmospheric methane and carbon dioxide during the Holocene epoch. However, the same thermokarst lakes can also sequester carbon, and it remains uncertain whether carbon uptake by thermokarst lakes can offset their greenhouse gas emissions. Here we use field observations of Siberian permafrost exposures, radiocarbon dating and spatial analyses to quantify Holocene carbon stocks and fluxes in lake sediments overlying thawed Pleistocene-aged permafrost. We find that carbon accumulation in deep thermokarst-lake sediments since the last deglaciation is about 1.6 times larger than the mass of Pleistocene-aged permafrost carbon released as greenhouse gases when the lakes first formed. Although methane and carbon dioxide emissions following thaw lead to immediate radiative warming, carbon uptake in peat-rich sediments occurs over millennial timescales. We assess thermokarst-lake carbon feedbacks to climate with an atmospheric perturbation model and find that thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5,000 years ago. High rates of Holocene carbon accumulation in 20 lake sediments (47 ± 10 grams of carbon per square metre per year; mean ± standard error) were driven by thermokarst erosion and deposition of terrestrial organic matter, by nutrient release from thawing permafrost that stimulated lake productivity and by slow decomposition in cold, anoxic lake bottoms. When lakes eventually drained, permafrost formation rapidly sequestered sediment carbon. Our estimate of about 160 petagrams of Holocene organic carbon in deep lake basins of Siberia and Alaska increases the circumpolar peat carbon pool estimate for permafrost regions by over 50 per cent (ref. 6). The carbon in perennially frozen drained lake sediments may become vulnerable to mineralization as permafrost disappears

  20. A shift of thermokarst lakes from carbon sources to sinks during the Holocene epoch

    USGS Publications Warehouse

    Walter Anthony, K. M.; Zimov, S. A.; Grosse, G.; Jones, Miriam C.; Anthony, P.; Chapin, F. S.; Finlay, J. C.; Mack, M. C.; Davydov, S.; Frenzel, P.F.; Frolking, S.

    2014-01-01

    Thermokarst lakes formed across vast regions of Siberia and Alaska during the last deglaciation and are thought to be a net source of atmospheric methane and carbon dioxide during the Holocene epoch1,2,3,4. However, the same thermokarst lakes can also sequester carbon5, and it remains uncertain whether carbon uptake by thermokarst lakes can offset their greenhouse gas emissions. Here we use field observations of Siberian permafrost exposures, radiocarbon dating and spatial analyses to quantify Holocene carbon stocks and fluxes in lake sediments overlying thawed Pleistocene-aged permafrost. We find that carbon accumulation in deep thermokarst-lake sediments since the last deglaciation is about 1.6 times larger than the mass of Pleistocene-aged permafrost carbon released as greenhouse gases when the lakes first formed. Although methane and carbon dioxide emissions following thaw lead to immediate radiative warming, carbon uptake in peat-rich sediments occurs over millennial timescales. We assess thermokarst-lake carbon feedbacks to climate with an atmospheric perturbation model and find that thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5,000 years ago. High rates of Holocene carbon accumulation in 20 lake sediments (47±10 grams of carbon per square metre per year; mean±standard error) were driven by thermokarst erosion and deposition of terrestrial organic matter, by nutrient release from thawing permafrost that stimulated lake productivity and by slow decomposition in cold, anoxic lake bottoms. When lakes eventually drained, permafrost formation rapidly sequestered sediment carbon. Our estimate of about 160petagrams of Holocene organic carbon in deep lake basins of Siberia and Alaska increases the circumpolar peat carbon pool estimate for permafrost regions by over 50 per cent (ref. 6). The carbon in perennially frozen drained lake sediments may become vulnerable to mineralization as permafrost disappears7

  1. Carbon source quality and placement effects on soil organic carbon status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improved management of agricultural soils has potential for sequestering carbon (C) and reducing the accumulation of atmospheric carbon dioxide. Development of management practices to increase C sequestration is dependent on improved understanding of soil processes influencing long-term storage of ...

  2. Mesozoic black shales, source mixing and carbon isotopes

    NASA Astrophysics Data System (ADS)

    Suan, Guillaume

    2016-04-01

    Over the last decades, considerable attention has been devoted to the paleoenvironmental and biogeochemical significance of Mesozoic black shales. Black shale-bearing successions indeed often display marked changes in the organic carbon isotope composition (δ13Corg), which have been commonly interpreted as evidence for dramatic perturbations of global carbon budgets and CO2 levels. Arguably the majority of these studies have discarded some more "local" explanations when interpreting δ13Corg profiles, most often because comparable profiles occur on geographically large and distant areas. Based on newly acquired data and selected examples from the literature, I will show that the changing contribution of organic components with distinct δ13C signatures exerts a major but overlooked influence of Mesozoic δ13Corg profiles. Such a bias occurs across a wide spectrum of sedimentological settings and ages, as shown by the good correlation between δ13Corg values and proxies of kerogen proportions (such as rock-eval, biomarker, palynofacies and palynological data) recorded in Mesozoic marginal to deep marine successions of Triassic, Jurassic and Cretaceous age. In most of these successions, labile, 12C-enriched amorphous organic matter of marine origin dominates strata deposited under anoxic conditions, while oxidation-resistant, 13C-rich terrestrial particles dominate strata deposited under well-oxygenated conditions. This influence is further illustrated by weathering profiles of Toarcian (Lower Jurassic) black shales from France, where weathered areas dominated by refractory organic matter show dramatic 13C-enrichment (and decreased total organic carbon and pyrite contents) compared to non-weathered portions of the same horizon. The implications of these results for chemostratigraphic correlations and pCO2 reconstructions of Mesozoic will be discussed, as well as strategies to overcome this major bias.

  3. Carbon sources and sinks in forest biomes of the former Soviet Union

    SciTech Connect

    Kolchugina, T.P.; Vinson, T.S.

    1993-06-01

    Net primary productivity (NPP) of Soviet forest biomes has been estimated from an equilibrium analysis at seven percent of the global terrestrial NPP, 20 percent of the world's total forest NPP, and half of boreal and temperate forest NPP. However, an equilibrium analysis does not allow the assessment of the role of forest biomes in carbon sequestration because it is based on the assumption that the annual carbon increment in forest biomes equals the amount of carbon released to the atmosphere through respiration. A non-equilibrium analysis accounts for carbon sequestration during specific stages of forest ecosystem development. Sources and sinks of carbon and the sequestration potential of forest biomes in the former Soviet Union are assessed in the present study under non-equilibrium conditions by considering (1) net ecosystem productivity of different age forest stands and their actual coverage, (2) carbon flux related to forest fires, (3) the rate of peat accumulation, and (4) anthropogenic influences.

  4. SESAME: a software tool for the numerical dosimetric reconstruction of radiological accidents involving external sources and its application to the accident in Chile in December 2005.

    PubMed

    Huet, C; Lemosquet, A; Clairand, I; Rioual, J B; Franck, D; de Carlan, L; Aubineau-Lanièce, I; Bottollier-Depois, J F

    2009-01-01

    Estimating the dose distribution in a victim's body is a relevant indicator in assessing biological damage from exposure in the event of a radiological accident caused by an external source. This dose distribution can be assessed by physical dosimetric reconstruction methods. Physical dosimetric reconstruction can be achieved using experimental or numerical techniques. This article presents the laboratory-developed SESAME--Simulation of External Source Accident with MEdical images--tool specific to dosimetric reconstruction of radiological accidents through numerical simulations which combine voxel geometry and the radiation-material interaction MCNP(X) Monte Carlo computer code. The experimental validation of the tool using a photon field and its application to a radiological accident in Chile in December 2005 are also described.

  5. Source and age of carbon in peatland surface waters: new insights from 14C analysis

    NASA Astrophysics Data System (ADS)

    Billett, Michael; Garnett, Mark; Dinsmore, Kerry; Leith, Fraser

    2013-04-01

    Peatlands are a significant source of carbon to the aquatic environment which is increasingly being recognised as an important flux pathway (both lateral and vertical) in total landscape carbon budgets. Determining the source and age of the carbon (in its various forms) is a key step to understanding the stability of peatland systems as well as the connectivity between the soil carbon pool and the freshwater environment. Novel analytical and sampling methods using molecular sieves have been developed for (1) within-stream, in situ sampling of CO2 in the field and (2) for the removal/separation of CO2 in the laboratory prior to 14C analysis of CH4. Here we present dual isotope (δ13C and 14C) data from freshwater systems in UK and Finnish peatlands to show that significant differences exist in the source and age of CO2, DOC (dissolved organic carbon) and POC (particulate organic carbon). Individual peatlands clearly differ in terms of their isotopic freshwater signature, suggesting that carbon cycling may be "tighter" in some systems compared to others. We have also measured the isotopic signature of different C species in peatland pipes, which appear to be able to tap carbon from different peat depths. This suggests that carbon cycling and transport within "piped-peatlands" may be more complex than previously thought. Some of our most recent work has focussed on the development of a method to measure the 14C component of CH4 in freshwaters. Initial results suggest that CH4 in peatland streams is significantly older than CO2 and derived from a much deeper source. We have also shown that the age (but not the source) of dissolved CO2 changes over the hydrological year in response to seasonal changes in discharge and temperature. Radiocarbon measurements in the peat-riparian-stream system suggest that a significant degree of connectivity exists in terms of C transport and cycling, although the degree of connectivity differs for individual C species. In summary, 14C

  6. Shift of thermokarst lakes from methane source to climate-cooling carbon sink

    NASA Astrophysics Data System (ADS)

    Walter Anthony, K. M.; Zimov, S. A.; Grosse, G.; Jones, M.; Anthony, P.; Chapin, T.; Finlay, J. C.; Mack, M. C.; Davydov, S. P.; Frenzel, P.; Frolking, S. E.

    2014-12-01

    Thermokarst lakes formed across vast regions of Siberia and Alaska during the last deglaciation and are thought to be a net source of atmospheric methane and carbon dioxide during the Holocene. However, the same thermokarst lakes can also sequester carbon, and it remains uncertain whether carbon uptake by thermokarst lakes can offset their greenhouse gas emissions. Here we use field observations of Siberian permafrost exposures, radiocarbon dating and spatial analyses to quantify Holocene carbon stocks and fluxes in lake sediments overlying thawed Pleistocene-aged permafrost. We find that carbon accumulation in deep thermokarst-lake sediments since the last deglaciation is about 1.6 times larger than the mass of Pleistocene-aged permafrost carbon released as greenhouse gases when the lakes first formed. While methane and carbon dioxide emissions following thaw lead to immediate radiative warming, carbon uptake in peat-rich sediments occurs over millennial time scales. With the help of an atmospheric perturbation model we assess thermokarst-lake carbon feedbacks to climate and find that thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5000 years ago. High rates of Holocene carbon accumulation in lake sediments (47 ± 10 g C m-2 a-1, mean ± SE, n=20 lakes) were driven by thermokarst erosion and deposition of terrestrial organic matter, by nutrient release from thawing permafrost that stimulated lake productivity and by slow decomposition in cold, anoxic lake bottoms. When lakes eventually drained, permafrost formation rapidly sequestered sediment carbon. Our estimate of about 160 Pg of Holocene organic carbon in deep lake basins of Siberia and Alaska increases the circumpolar peat carbon pool estimate for permafrost regions by over 50 percent. The carbon in perennially-frozen drained lake sediments may become vulnerable to mineralization as permafrost disappears, potentially negating the climate stabilization provided by

  7. [Carbon sources metabolic characteristics of airborne microbial communities in constructed wetlands].

    PubMed

    Song, Zhi-Wen; Wang, Lin; Xu, Ai-Ling; Wu, Deng-Deng; Xia, Yan

    2015-02-01

    Using BIOLOG-GN plates, this article describes the carbon sources metabolic characteristics of airborne microbial communities in a free surface-flow constructed wetland in different seasons and clarify the correlation between airborne microbial metabolic functions and environmental factors. The average well color development (AWCD), carbon metabolic profiles and McIntosh values of airborne microbial communities in different seasons were quite different. Analysis of the variations showed that AWCD in spring and summer differed significantly from that in autumn and winter (P < 0.01). In the same season, the degree of utilization of different types of carbon by airborne microbes was different. Summer had a significant difference from other seasons (P < 0.05). Dominant communities of airborne microbes in four seasons were carboxylic acids metabolic community, carbohydrates metabolic community, polymers metabolic community and carboxylic acids metabolic community respectively. Principal component analysis showed that the carbon metabolic characteristics of airborne microbial community in autumn were similar to those in winter but different from those in spring and summer. The characteristics of carbon metabolism revealed differences between summer and spring, autumn, or winter. These differences were mainly caused by amines or amides while the differences between spring and autumn or winter were mainly caused by carboxylic acids. Environmental factors, including changes in wind speed, temperature, and humidity acted to influence the carbon sources metabolic properties of airborne microbial community. The dominant environmental factors that acted to influence the carbon sources metabolic properties of airborne microbial community varied between different seasons.

  8. [Harvest of the carbon source in wastewater by the adsorption and desorption of activated sludge].

    PubMed

    Liu, Hong-Bo; Wen, Xiang-Hua; Zhao, Fang; Mei, Yi-Jun

    2011-04-01

    The carbon source in municipal wastewater was adsorbed by activated sludge and then harvested through the hydrolysis of activated sludge. Results indicated that activated sludge had high absorbing ability towards organic carbon and phosphorus under continuous operation mode, and the average COD and TP absorption rate reached as high as 63% and 76%, respectively. Moreover, about 50% of the soluble carbon source was outside of the sludge cell and could be released under mild hydrolysis condition. Whereas the absorbed amount of nitrogen was relatively low, and the removal rate of ammonia was only 13% . Furthermore, the releases of organic carbon, nitrogen and phosphorus from the sludge absorbing pollutants in the wastewater were studied. By comparing different hydrolysis conditions of normal (pH 7.5, 20 degrees C), heating (pH 7.5, 60 degrees C) and the alkaline heating (pH 11, 60 degrees C), the last one presented the optimum hydrolysis efficiency. Under which, the release rate of COD could reach 320 mg/g after 24 hours, whereas nitrogen and phosphorus just obtained low release rates of 18 mg/g and 2 mg/g, respectively. Results indicate that the carbon source in wastewater could be harvested by the adsorption and desorption of activated sludge, and the concentrations of nitrogen and phosphorus are low and would not influence the reuse of the harvested carbon source.

  9. Source and sink carbon dynamics and carbon allocation in the Amazon basin

    NASA Astrophysics Data System (ADS)

    Doughty, Christopher E.; Metcalfe, D. B.; Girardin, C. A. J.; Amezquita, F. F.; Durand, L.; Huaraca Huasco, W.; Silva-Espejo, J. E.; Araujo-Murakami, A.; Costa, M. C.; Costa, A. C. L.; Rocha, W.; Meir, P.; Galbraith, D.; Malhi, Y.

    2015-05-01

    Changes to the carbon cycle in tropical forests could affect global climate, but predicting such changes has been previously limited by lack of field-based data. Here we show seasonal cycles of the complete carbon cycle for 14, 1 ha intensive carbon cycling plots which we separate into three regions: humid lowland, highlands, and dry lowlands. Our data highlight three trends: (1) there is differing seasonality of total net primary productivity (NPP) with the highlands and dry lowlands peaking in the dry season and the humid lowland sites peaking in the wet season, (2) seasonal reductions in wood NPP are not driven by reductions in total NPP but by carbon during the dry season being preferentially allocated toward either roots or canopy NPP, and (3) there is a temporal decoupling between total photosynthesis and total carbon usage (plant carbon expenditure). This decoupling indicates the presence of nonstructural carbohydrates which may allow growth and carbon to be allocated when it is most ecologically beneficial rather than when it is most environmentally available.

  10. Organic carbon source and burial during the past one hundred years in Jiaozhou Bay, North china.

    PubMed

    Li, Xuegang; Yuan, Huamao; Li, Ning; Song, Jinming

    2008-01-01

    Organic carbon (OC), total nitrogen (TN), and 210Pb in core sediment were measured to quantify the burial of organic carbon and the relative importance of allochthonous and autochthonous contributions during the past one hundred years in Jiaozhou Bay, North China. The core sediment was dated using 210Pb chronology, which is the most promising method for estimation of sedimentation rate on a time scale of 100-150 years. The variation of the burial flux of organic carbon in the past one hundred years can be divided into the following three stages: (1) relatively steady before 1980s; (2) increasing rapidly from the 1980s to a peak in the 1990s, and (3) decreasing from the 1990s to the present. The change is consistent with the amount of solid waste and sewage emptied into the bay. The OC:TN ratio was used to evaluate the source of organic carbon in the Jiaozhou Bay sediment. In the inner bay and bay mouth, the organic carbon was the main contributor from terrestrial sources, whereas only about half of organic carbon was contributed from terrestrial source in the outer bay. In the inner bay, the terrestrial source of organic carbon showed a steady change with an increase in the range of 69%-77% before 1990 to 93% in 2000, and then decreased from 2000 because of the decrease in the terrestrial input. In the bay mouth, the percentage of organic carbon from land reached the highest value with 94% in 1994. In the outer bay, the sediment source maintained steady for the past one hundred years.

  11. [Quantitative estimation source of urban atmospheric CO2 by carbon isotope composition].

    PubMed

    Liu, Wei; Wei, Nan-Nan; Wang, Guang-Hua; Yao, Jian; Zeng, You-Shi; Fan, Xue-Bo; Geng, Yan-Hong; Li, Yan

    2012-04-01

    To effectively reduce urban carbon emissions and verify the effectiveness of currently project for urban carbon emission reduction, quantitative estimation sources of urban atmospheric CO2 correctly is necessary. Since little fractionation of carbon isotope exists in the transportation from pollution sources to the receptor, the carbon isotope composition can be used for source apportionment. In the present study, a method was established to quantitatively estimate the source of urban atmospheric CO2 by the carbon isotope composition. Both diurnal and height variations of concentrations of CO2 derived from biomass, vehicle exhaust and coal burning were further determined for atmospheric CO2 in Jiading district of Shanghai. Biomass-derived CO2 accounts for the largest portion of atmospheric CO2. The concentrations of CO2 derived from the coal burning are larger in the night-time (00:00, 04:00 and 20:00) than in the daytime (08:00, 12:00 and 16:00), and increase with the increase of height. Those derived from the vehicle exhaust decrease with the height increase. The diurnal and height variations of sources reflect the emission and transport characteristics of atmospheric CO2 in Jiading district of Shanghai.

  12. Effect of carbon source on nitrogen removal in anaerobic ammonium oxidation (anammox) process.

    PubMed

    Zhu, Weiqiang; Zhang, Peiyu; Dong, Huiyu; Li, Jin

    2017-04-01

    Anaerobic ammonium oxidation (anammox) has been regarded as an efficient process to treat high-strength wastewater without organic carbon source. To investigate nitrogen removal performance of anammox in presence of organic carbon source can broaden its application on organic wastewater treatment. In this work, effect of carbon source on anammox process was explored. Operating temperature was set at 35 ± 1°C. Influent pH and hydraulic retention time were 7.5 and 6 h, respectively. Effluent [Formula: see text] was affected little with COD no more than 480 mg/L. Independent of carbon source content, nitrite removal rate was around 99%. The variation of [Formula: see text] lagged behind [Formula: see text] at high COD content, and pH could be used as an indicator for [Formula: see text] removal. Specific anammox activity dropped from 0.39 to 0.19  [Formula: see text] at COD=720 mg/L. The remodified logistic model was quite appropriate for describing the nitrogen removal kinetics and predicting the performance of anammox process in presence of carbon source.

  13. A simple and clean source of low-energy atomic carbon

    SciTech Connect

    Krasnokutski, S. A.; Huisken, F.

    2014-09-15

    A carbon source emitting low-energy carbon atoms from a thin-walled, sealed tantalum tube via thermal evaporation has been constructed. The tube is made from a 0.05 mm thick tantalum foil and filled with {sup 12}C or {sup 13}C carbon powder. After being sealed, it is heated by direct electric current. The solvated carbon atoms diffuse to the outer surface of the tube and, when the temperature rises over 2200 K, the evaporation of atomic carbon from the surface of the tantalum tube is observed. As the evaporated species have low energy they are well-suited for the incorporation into liquid helium droplets by the pick-up technique. Mass analysis of the incorporated species reveals the dominant presence of atomic carbon and very low abundances of C{sub 2} and C{sub 3} molecules (<1%). This is in striking contrast to the thermal evaporation of pure carbon, where C{sub 3} molecules are found to be the dominant species in the gas phase. Due to the thermal evaporation and the absence of high-energy application required for the dissociation of C{sub 2} and C{sub 3} molecules, the present source provides carbon atoms with rather low energy.

  14. External forcing as a source for the observed multi-decadal relation between AMV and the Indian summer monsoon

    NASA Astrophysics Data System (ADS)

    Svendsen, Lea; Luo, Feifei; Sankar, Syam; Gao, Yongqi; Keenlyside, Noel; Vareed Joseph, Porathur; Johannessen, Ola

    2016-04-01

    The instrumental records show a significant positive correlation between the Atlantic multi-decadal variability (AMV) and the Indian summer monsoon (ISM) rainfall, where a positive (negative) AMV is associated with more (less) ISM rainfall. We have used both proxy reconstruction and twelve models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to investigate if the observed AMV-ISM relation is a persistent internal climate signal or externally forced. A comparison of several annual resolution proxy records both from the Atlantic and for the ISM show that the multi-decadal variability in both indices is persistent, but the link between them is not. The correlation between the two regions is weak, and even negative in some periods, before the instrumental time period. The analysis of CMIP5 simualtions is consistent with these results. While none of the CMIP5 models investigated simulate the significant AMV-ISM connection in the pre-industrial control simulations with fixed external forcing, three of the models reproduce the relation in the 20th century historical simulations with transient forcing. In these models external forcing is linked to the mid-to-upper tropospheric temperature pattern with a strengthened land-ocean contrast over South Asia, consistent with an enhanced ISM, as well as the evolution of AMV. We conclude that the significant AMV-ISM relation found in the observations after the industrial revolution may be associated with external forcing, rather than being internal climate variability.

  15. Electron string ion sources for carbon ion cancer therapy accelerators.

    PubMed

    Boytsov, A Yu; Donets, D E; Donets, E D; Donets, E E; Katagiri, K; Noda, K; Ponkin, D O; Ramzdorf, A Yu; Salnikov, V V; Shutov, V B

    2015-08-01

    The type of the Electron String Ion Sources (ESIS) is considered to be the appropriate one to produce pulsed C(4+) and C(6+) ion beams for cancer therapy accelerators. In fact, the new test ESIS Krion-6T already now provides more than 10(10) C(4+) ions per pulse and about 5 × 10(9) C(6+) ions per pulse. Such ion sources could be suitable to apply at synchrotrons. It has also been found that Krion-6T can provide more than 10(11) C(6+) ions per second at the 100 Hz repetition rate, and the repetition rate can be increased at the same or larger ion output per second. This makes ESIS applicable at cyclotrons as well. ESIS can be also a suitable type of ion source to produce the (11)C radioactive ion beams. A specialized cryogenic cell was experimentally tested at the Krion-2M ESIS for pulse injection of gaseous species into the electron string. It has been shown in experiments with stable methane that the total conversion efficiency of methane molecules to C(4+) ions reached 5%÷10%. For cancer therapy with simultaneous irradiation and precise dose control (positron emission tomography) by means of (11)C, transporting to the tumor with the primary accelerated (11)C(4+) beam, this efficiency is preliminarily considered to be large enough to produce the (11)C(4+) beam from radioactive methane and to inject this beam into synchrotrons.

  16. Sources and yields of dissolved carbon in northern Wisconsin stream catchments with differing amounts of Peatland

    USGS Publications Warehouse

    Elder, J.F.; Rybicki, N.B.; Carter, V.; Weintraub, V.

    2000-01-01

    In five tributary streams (four inflowing and one outflowing) of 1600-ha Trout Lake in northern Wisconsin, USA, we examined factors that can affect the magnitude of stream flow and transport of dissolved organic and inorganic carbon (DOC and DIC) through the streams to the lake. One catchment, the Allequash Creek basin, was investigated in more detail to describe the dynamics of carbon flow and to identify potential carbon sources. Stream flows and carbon loads showed little or no relation to surface-water catchment area. They were more closely related to ground-water watershed area because ground-water discharge, from both local and regional sources, is a major contributor to the hydrologic budgets of these catchments. An important factor in determining carbon influx to the stream is the area of peatland in the catchment. Peatland porewaters contain DOC concentrations up to 40 mg l-1 and are a significant potential carbon source. Ground-water discharge and lateral flow through peat are the suspected mechanisms for transport of that carbon to the streams. Carbon and nitrogen isotopes suggested that the sources of DOC in Allequash Creek above Allequash Lake were wetland vegetation and peat and that the sources below Allequash Lake were filamentous algae and wild rice. Catchments with high proportions of peatland, including the Allequash Creek catchment, tended to have elevated DOC loads in outflowing stream water. Respiration and carbon mineralization in lakes within the system tend to produce low DOC and low DOC/DIC in lake outflows, especially at Trout Lake. In Allequash Lake, however, the shallow peat island and vegetation-filled west end were sources of DOC. Despite the vast carbon reservoir in the peatlands, carbon yields were very low in these catchments. Maximum yields were on the order of 2.5 g m-2 y-1 DOC and 5.5 g m-2 y-1 DIC. The small yields were attributable to low stream flows due to lack of significant overland runoff and very limited stream channel

  17. Mineral Carbonation Potential of CO2 from Natural and Industrial-based Alkalinity Sources

    NASA Astrophysics Data System (ADS)

    Wilcox, J.; Kirchofer, A.

    2014-12-01

    Mineral carbonation is a Carbon Capture and Storage (CSS) technology where gaseous CO2 is reacted with alkaline materials (such as silicate minerals and alkaline industrial wastes) and converted into stable and environmentally benign carbonate minerals (Metz et al., 2005). Here, we present a holistic, transparent life cycle assessment model of aqueous mineral carbonation built using a hybrid process model and economic input-output life cycle assessment approach. We compared the energy efficiency and the net CO2 storage potential of various mineral carbonation processes based on different feedstock material and process schemes on a consistent basis by determining the energy and material balance of each implementation (Kirchofer et al., 2011). In particular, we evaluated the net CO2 storage potential of aqueous mineral carbonation for serpentine, olivine, cement kiln dust, fly ash, and steel slag across a range of reaction conditions and process parameters. A preliminary systematic investigation of the tradeoffs inherent in mineral carbonation processes was conducted and guidelines for the optimization of the life-cycle energy efficiency are provided. The life-cycle assessment of aqueous mineral carbonation suggests that a variety of alkalinity sources and process configurations are capable of net CO2 reductions. The maximum carbonation efficiency, defined as mass percent of CO2 mitigated per CO2 input, was 83% for CKD at ambient temperature and pressure conditions. In order of decreasing efficiency, the maximum carbonation efficiencies for the other alkalinity sources investigated were: olivine, 66%; SS, 64%; FA, 36%; and serpentine, 13%. For natural alkalinity sources, availability is estimated based on U.S. production rates of a) lime (18 Mt/yr) or b) sand and gravel (760 Mt/yr) (USGS, 2011). The low estimate assumes the maximum sequestration efficiency of the alkalinity source obtained in the current work and the high estimate assumes a sequestration efficiency

  18. Sources and mixing state of size-resolved elemental carbon particles in a European megacity: Paris

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Sciare, J.; Poulain, L.; Kamili, K.; Merkel, M.; Müller, T.; Wiedensohler, A.; Eckhardt, S.; Stohl, A.; Sarda-Estève, R.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Wenger, J. C.

    2012-02-01

    An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed to investigate the size-resolved chemical composition of single particles at an urban background site in Paris, France, as part of the MEGAPOLI winter campaign in January/February 2010. ATOFMS particle counts were scaled to match coincident Twin Differential Mobility Particle Sizer (TDMPS) data in order to generate hourly size-resolved mass concentrations for the single particle classes observed. The total scaled ATOFMS particle mass concentration in the size range 150-1067 nm was found to agree very well with the sum of concurrent High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and Multi-Angle Absorption Photometer (MAAP) mass concentration measurements of organic carbon (OC), inorganic ions and black carbon (BC) (R2 = 0.91). Clustering analysis of the ATOFMS single particle mass spectra allowed the separation of elemental carbon (EC) particles into four classes: (i) EC attributed to biomass burning (ECbiomass), (ii) EC attributed to traffic (ECtraffic), (iii) EC internally mixed with OC and ammonium sulfate (ECOCSOx), and (iv) EC internally mixed with OC and ammonium nitrate (ECOCNOx). Average hourly mass concentrations for EC-containing particles detected by the ATOFMS were found to agree reasonably well with semi-continuous quantitative thermal/optical EC and optical BC measurements (r2 = 0.61 and 0.65-0.68 respectively, n = 552). The EC particle mass assigned to fossil fuel and biomass burning sources also agreed reasonably well with BC mass fractions assigned to the same sources using seven-wavelength aethalometer data (r2 = 0.60 and 0.48, respectively, n = 568). Agreement between the ATOFMS and other instrumentation improved noticeably when a period influenced by significantly aged, internally mixed EC particles was removed from the intercomparison. 88% and 12% of EC particle mass was apportioned to fossil fuel and biomass burning respectively using the ATOFMS data

  19. Sources and mixing state of size-resolved elemental carbon particles in a European megacity: Paris

    NASA Astrophysics Data System (ADS)

    Healy, R. M.; Sciare, J.; Poulain, L.; Kamili, K.; Merkel, M.; Müller, T.; Wiedensohler, A.; Eckhardt, S.; Stohl, A.; Sarda-Estève, R.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Wenger, J. C.

    2011-11-01

    An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) was deployed to investigate the size-resolved chemical composition of single particles at an urban background site in Paris, France, as part of the MEGAPOLI winter campaign in January/February 2010. ATOFMS particle counts were scaled to match coincident Twin Differential Mobility Particle Sizer (TDMPS) data in order to generate hourly size-resolved mass concentrations for the single particle classes observed. The total scaled ATOFMS particle mass concentration in the size range 150-1067 nm was found to agree very well with the sum of concurrent High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and Multi-Angle Absorption Photometer (MAAP) mass concentration measurements of organic carbon (OC), inorganic ions and black carbon (BC) (R2 = 0.91). Clustering analysis of the ATOFMS single particle mass spectra allowed the separation of elemental carbon (EC) particles into four classes: (i) EC attributed to biomass burning (ECbiomass), (ii) EC attributed to traffic (ECtraffic), (iii) EC internally mixed with OC and ammonium sulfate (ECOCSOx), and (iv) EC internally mixed with OC and ammonium nitrate (ECOCNOx). Average hourly mass concentrations for EC-containing particles detected by the ATOFMS were found to agree reasonably well with semi-continuous quantitative thermal/optical EC and optical BC measurements (r2 = 0.61 and 0.65-0.68, respectively, n = 552). The EC particle mass assigned to fossil fuel and biomass burning sources also agreed reasonably well with BC mass fractions assigned to the same sources using seven-wavelength aethalometer data (r2 = 0.60 and 0.48, respectively, n = 568). Agreement between the ATOFMS and other instrumentation improved noticeably when a period influenced by significantly aged, internally mixed EC particles was removed from the intercomparison. 88 % and 12 % of EC particle mass was apportioned to fossil fuel and biomass burning respectively using the ATOFMS data

  20. Carbon source/sink function of a subtropical, eutrophic lake determined from an overall mass balance and a gas exchange and carbon burial balance.

    PubMed

    Yang, Hong; Xing, Yangping; Xie, Ping; Ni, Leyi; Rong, Kewen

    2008-02-01

    Although studies on carbon burial in lake sediments have shown that lakes are disproportionately important carbon sinks, many studies on gaseous carbon exchange across the water-air interface have demonstrated that lakes are supersaturated with CO(2) and CH(4) causing a net release of CO(2) and CH(4) to the atmosphere. In order to more accurately estimate the net carbon source/sink function of lake ecosystems, a more comprehensive carbon budget is needed, especially for gaseous carbon exchange across the water-air interface. Using two methods, overall mass balance and gas exchange and carbon burial balance, we assessed the carbon source/sink function of Lake Donghu, a subtropical, eutrophic lake, from April 2003 to March 2004. With the overall mass balance calculations, total carbon input was 14 905 t, total carbon output was 4950 t, and net carbon budget was +9955 t, suggesting that Lake Donghu was a great carbon sink. For the gas exchange and carbon burial balance, gaseous carbon (CO(2) and CH(4)) emission across the water-air interface totaled 752 t while carbon burial in the lake sediment was 9477 t. The ratio of carbon emission into the atmosphere to carbon burial into the sediment was only 0.08. This low ratio indicates that Lake Donghu is a great carbon sink. Results showed good agreement between the two methods with both showing Lake Donghu to be a great carbon sink. This results from the high primary production of Lake Donghu, substantive allochthonous carbon inputs and intensive anthropogenic activity. Gaseous carbon emission accounted for about 15% of the total carbon output, indicating that the total output would be underestimated without including gaseous carbon exchange.

  1. What's on the menu? Assessing microbial carbon sources and cycling in soils using natural abundance radiocarbon analysis

    NASA Astrophysics Data System (ADS)

    Mahmoudi, N.; Burns, L.; Mancini, S.; Fulthorpe, R.; Slater, G. F.

    2011-12-01

    Organic matter in soils is composed of diverse materials in various stages of decomposition. Soil organic matter is not in a single pool but rather in multiple carbon pools with different intrinsic turnover times that can be on annual to decadal and even millennial timescales. Microorganisms can influence the total amount of carbon stored in soils and the turnover rates of these different pools. However, the links between microbes and their ability to utilize these various carbon pools are not well understood. Moreover, microbes have been shown to co-utilize a number of available carbon sources rather than a single carbon source under soil conditions which creates difficulties in identifying microbial carbon sources in the natural environment. Compound-specific radiocarbon analysis of microbial phospholipid fatty acids (PLFA) has become a useful tool in elucidating microbial carbon sources in complex environments with multiple carbon sources. We investigated microbial carbon cycling at an industrial site in Ontario which included a variety of carbon sources including vegetation, PAHs and natural organic matter (NOM). Using this approach, the 14C content of microbial membrane lipids (which reflects their carbon source) can be compared to surrounding carbon sources in order to assess which carbon source they are metabolizing and incorporating into their lipids. In addition, we assessed microbial community structure and diversity by analyzing amplified bacterial, eukaryotic and archaeal rDNA fragments with denaturing gel gradient electrophoresis (DGGE). The Δ14C value for PLFAs ranged from +54 to -697% which indicates that microbial carbon sources across soils differ. The Δ14CPLFA for some soils is consistent with modern carbon sources while Δ14CPLFA for other soils is consistent with natural organic matter including older pools of carbon. The microbial communities at this site are not metabolizing PAHs but rather they are utilizing various pools of natural organic

  2. Organic carbon sources and sinks in San Francisco Bay: variability induced by river flow

    USGS Publications Warehouse

    Jassby, Alan D.; Powell, T.M.; Cloern, James E.

    1993-01-01

    Sources and sinks of organic carbon for San Francisco Bay (California, USA) were estimated for 1980. Sources for the southern reach were dominated by phytoplankton and benthic microalgal production. River loading of organic matter was an additional important factor in the northern reach. Tidal marsh export and point sources played a secondary role. Autochthonous production in San Francisco Bay appears to be less than the mean for temperate-zone estuaries, primarily because turbidity limits microalgal production and the development of seagrass beds. Exchange between the Bay and Pacific Ocean plays an unknown but potentially important role in the organic carbon balance. Interannual variability in the organic carbon supply was assessed for Suisun Bay, a northern reach subembayment that provides habitat for important fish species (delta smelt Hypomesus transpacificus and larval striped bass Morone saxatilus). The total supply fluctuated by an order of magnitude; depending on the year, either autochthonous sources (phytoplankton production) or allochthonous sources (riverine loading) could be dominant. The primary cause of the year-to-year change was variability of freshwater inflows from the Sacramento and San Joaquin rivers, and its magnitude was much larger than long-term changes arising from marsh destruction and point source decreases. Although interannual variability of the total organic carbon supply could not be assessed for the southern reach, year-to-year changes in phytoplankton production were much smaller than in Suisun Bay, reflecting a relative lack of river influence.

  3. Climatic variability, hydrologic anomaly, and methane emission can turn productive freshwater marshes into net carbon sources.

    PubMed

    Chu, Housen; Gottgens, Johan F; Chen, Jiquan; Sun, Ge; Desai, Ankur R; Ouyang, Zutao; Shao, Changliang; Czajkowski, Kevin

    2015-03-01

    Freshwater marshes are well-known for their ecological functions in carbon sequestration, but complete carbon budgets that include both methane (CH4 ) and lateral carbon fluxes for these ecosystems are rarely available. To the best of our knowledge, this is the first full carbon balance for a freshwater marsh where vertical gaseous [carbon dioxide (CO2 ) and CH4 ] and lateral hydrologic fluxes (dissolved and particulate organic carbon) have been simultaneously measured for multiple years (2011-2013). Carbon accumulation in the sediments suggested that the marsh was a long-term carbon sink and accumulated ~96.9 ± 10.3 (±95% CI) g C m(-2)  yr(-1) during the last ~50 years. However, abnormal climate conditions in the last 3 years turned the marsh to a source of carbon (42.7 ± 23.4 g C m(-2)  yr(-1) ). Gross ecosystem production and ecosystem respiration were the two largest fluxes in the annual carbon budget. Yet, these two fluxes compensated each other to a large extent and led to the marsh being a CO2 sink in 2011 (-78.8 ± 33.6 g C m(-2)  yr(-1) ), near CO2 -neutral in 2012 (29.7 ± 37.2 g C m(-2)  yr(-1) ), and a CO2 source in 2013 (92.9 ± 28.0 g C m(-2)  yr(-1) ). The CH4 emission was consistently high with a three-year average of 50.8 ± 1.0 g C m(-2)  yr(-1) . Considerable hydrologic carbon flowed laterally both into and out of the marsh (108.3 ± 5.4 and 86.2 ± 10.5 g C m(-2)  yr(-1) , respectively). In total, hydrologic carbon fluxes contributed ~23 ± 13 g C m(-2)  yr(-1) to the three-year carbon budget. Our findings highlight the importance of lateral hydrologic inflows/outflows in wetland carbon budgets, especially in those characterized by a flow-through hydrologic regime. In addition, different carbon fluxes responded unequally to climate variability/anomalies and, thus, the total carbon budgets may vary drastically among years.

  4. Electron string ion sources for carbon ion cancer therapy accelerators

    SciTech Connect

    Boytsov, A. Yu.; Donets, D. E.; Donets, E. D.; Donets, E. E.; Ponkin, D. O.; Ramzdorf, A. Yu.; Salnikov, V. V.; Shutov, V. B.; Katagiri, K.; Noda, K.

    2015-08-15

    The type of the Electron String Ion Sources (ESIS) is considered to be the appropriate one to produce pulsed C{sup 4+} and C{sup 6+} ion beams for cancer therapy accelerators. In fact, the new test ESIS Krion-6T already now provides more than 10{sup 10} C{sup 4+} ions per pulse and about 5 × 10{sup 9} C{sup 6+} ions per pulse. Such ion sources could be suitable to apply at synchrotrons. It has also been found that Krion-6T can provide more than 10{sup 11} C{sup 6+} ions per second at the 100 Hz repetition rate, and the repetition rate can be increased at the same or larger ion output per second. This makes ESIS applicable at cyclotrons as well. ESIS can be also a suitable type of ion source to produce the {sup 11}C radioactive ion beams. A specialized cryogenic cell was experimentally tested at the Krion-2M ESIS for pulse injection of gaseous species into the electron string. It has been shown in experiments with stable methane that the total conversion efficiency of methane molecules to C{sup 4+} ions reached 5%÷10%. For cancer therapy with simultaneous irradiation and precise dose control (positron emission tomography) by means of {sup 11}C, transporting to the tumor with the primary accelerated {sup 11}C{sup 4+} beam, this efficiency is preliminarily considered to be large enough to produce the {sup 11}C{sup 4+} beam from radioactive methane and to inject this beam into synchrotrons.

  5. Carbon Sequestration through Sustainably Sourced Algal Fertilizer: Deep Ocean Water.

    NASA Astrophysics Data System (ADS)

    Sherman, M. T.

    2014-12-01

    Drawing down carbon from the atmosphere happens in the oceans when marine plants are growing due to the use of carbon dioxide for biological processes and by raising the pH of the water. Macro- and microscopic marine photosynthesizers are limited in their growth by the availability of light and nutrients (nitrogen, phosphorous, iron, etc.) Deep ocean water (DOW), oceanic water from bellow about 1000m, is a natural medium for marine algae, which contains all (except in rare circumstances) necessary components for algal growth and represents over 90% of the volume of the ocean. The introduction of DOW to a tropical or summer sea can increase chlorophyll from near zero to 60 mg per M3 or more. The form of the utilization infrastructure for DOW can roughly be divided into two effective types; the unconstrained release and the open pond system. Unconstrained release has the advantage of having relatively low infrastructure investment and is available to any area of the ocean. The open pond system has high infrastructure costs but enables intensive use of DOW for harvesting macro- and microalgae and sustainable mariculture. It also enables greater concomitant production of DOW's other potential products such as electricity or potable water. However, unlike an unconstrained release the open pond system can capture much of the biomaterial from the water and limits the impact to the surrounding ecosystem. The Tidal Irrigation and Electrical System (TIESystem), is an open pond that is to be constructed on a continental shelf. It harnesses the tidal flux to pump DOW into the pond on the rising tide and then uses the falling tide to pump biologically rich material out of the pond. This biomaterial represents fixed CO2 and can be used for biofuel or fertilizers. The TIESystem benefits from an economy of scale that increases at a rate that is roughly equal to the relationship of the circumference of a circle (the barrier that creates the open pond) to the area of the pond

  6. Sources and sinks of carbon in boreal ecosystems of interior Alaska: a review

    USGS Publications Warehouse

    Douglas, Thomas A.; Jones, Miriam C.; Hiemstra, Christopher A.

    2014-01-01

    Boreal regions store large quantities of carbon but are increasingly vulnerable to carbon loss due to disturbance and climate warming. The boreal region, underlain by discontinuous permafrost, presents a challenging landscape for itemizing current and potential carbon sources and sinks in the boreal soil and vegetation. The roles of fire, forest succession, and the presence (or absence) of permafrost on carbon cycle, vegetation, and hydrologic processes have been the focus of multidisciplinary research in this area for the past 20 years. However, projections of a warming future climate, an increase in fire severity and extent, and the potential degradation of permafrost could lead to major landscape process changes over the next 20 to 50 years. This provides a major challenge for predicting how the interplay between land management activities and impacts of climate warming will affect carbon sources and sinks in Interior Alaska. To assist land managers in adapting and managing for potential changes in the Interior Alaska carbon cycle we developed this review paper incorporating an overview of the climate, ecosystem processes, vegetation types, and soil regimes in Interior Alaska with a focus on ramifications for the carbon cycle. Our objective is to provide a synthesis of the most current carbon storage estimates and measurements to support policy and land management decisions on how to best manage carbon sources and sinks in Interior Alaska. To support this we have surveyed relevant peer reviewed estimates of carbon stocks in aboveground and belowground biomass for Interior Alaska boreal ecosystems. We have also summarized methane and carbon dioxide fluxes from the same ecosystems. These data have been converted into the same units to facilitate comparison across ecosystem compartments. We identify potential changes in the carbon cycle with climate change and human disturbance including how compounding disturbances can affect the boreal system. Finally, we provide

  7. Inorganic carbon and fossil organic carbon are source of bias for quantification of sequestered carbon in mine spoil

    NASA Astrophysics Data System (ADS)

    Vindušková, Olga; Frouz, Jan

    2016-04-01

    Carbon sequestration in mine soils has been studied as a possibility to mitigate the rising atmospheric CO2 levels and to improve mine soil quality (Vindu\\vsková and Frouz, 2013). Moreover, these soils offer an unique opportunity to study soil carbon dynamics using the chronosequence approach (using a set of sites of different age on similar parent material). However, quantification of sequestered carbon in mine soils is often complicated by fossil organic carbon (e.g., from coal or kerogen) or inorganic carbon present in the spoil. We present a methodology for quantification of both of these common constituents of mine soils. Our recommendations are based on experiments done on post-mining soils in Sokolov basin, Czech Republic. Here, fossil organic carbon is present mainly as kerogen Type I and II and represents 2-6 wt.% C in these soils. Inorganic carbon in these soils is present mainly as siderite (FeCO3), calcite (CaCO3), and dolomite (CaMg(CO3)2). All of these carbonates are often found in the overburden of coal seams thus being a common constituent of post-mining soils in the world. Vindu\\vsková O, Frouz J, 2013. Soil carbon accumulation after open-cast coal and oil shale mining in Northern Hemisphere: a quantitative review. ENVIRONMENTAL EARTH SCIENCES, 69: 1685-1698. Vindu\\vsková O, Dvořáček V, Prohasková A, Frouz J. 2014. Distinguishing recent and fossil organic matter - A critical step in evaluation of post-mining soil development - using near infrared spectroscopy. ECOLOGICAL ENGINEERING. 73: 643-648. Vindu\\vsková O, Sebag D, Cailleau G, Brus J, Frouz J. 2015. Methodological comparison for quantitative analysis of fossil and recently derived carbon in mine soils with high content of aliphatic kerogen. ORGANIC GEOCHEMISTRY, 89-90:14-22.

  8. Constraining carbon sources and growth rates of freshwater microbialites in Pavilion Lake using (14)C analysis.

    PubMed

    Brady, A L; Slater, G; Laval, B; Lim, D S

    2009-12-01

    This study determined the natural abundance isotopic compositions ((13)C, (14)C) of the primary carbon pools and microbial communities associated with modern freshwater microbialites located in Pavilion Lake, British Columbia, Canada. The Delta(14)C of dissolved inorganic carbon (DIC) was constant throughout the water column and consistent with a primarily atmospheric source. Observed depletions in DIC (14)C values compared with atmospheric CO(2) indicated effects due either to DIC residence time and/or inputs of (14)C-depleted groundwater. Mass balance comparisons of local and regional groundwater indicate that groundwater DIC could contribute a maximum of 9-13% of the DIC. (14)C analysis of microbial phospholipid fatty acids from microbialite communities had Delta(14)C values comparable with lake water DIC, demonstrating that lake water DIC was their primary carbon source. Microbialite carbonate was also primarily derived from DIC. However, some depletion in microbialite carbonate (14)C relative to lake water DIC occurred, due either to residence time or mixing with a (14)C-depleted carbon source. A detrital branch covered with microbialite growth was used to estimate a microbialite growth rate of 0.05 mm year(-1) for the past 1000 years, faster than previous estimates for this system. These results demonstrate that the microbialites are actively growing and that the primary carbon source for both microbial communities and recent carbonate is DIC originating from the atmosphere. While these data cannot conclusively differentiate between abiotic and biotic formation mechanisms, the evidence for minor inputs of groundwater-derived DIC is consistent with the previously hypothesized biological origin of the Pavilion Lake microbialites.

  9. Influence of natural and novel organic carbon sources on denitrification in forest, degraded urban, and restored streams

    EPA Science Inventory

    Organic carbon is important in regulating ecosystem function, and its source and abundance may be altered by urbanization. We investigated shifts in organic carbon quantity and quality associated with urbanization and ecosystem restoration, and its potential effects on denitrific...

  10. A new activated primary tank developed for recovering carbon source and its application.

    PubMed

    Jin, Pengkang; Wang, Xianbao; Zhang, Qionghua; Wang, Xiaochang; Ngo, Huu Hao; Yang, Lei

    2016-01-01

    A novel activated primary tank process (APT) was developed for recovering carbon source by fermentation and elutriation of primary sludge. The effects of solids retention time (SRT), elutriation intensity (G) and return sludge ratio (RSR) on this recovery were evaluated in a pilot scale reactor. Results indicated that SRT significantly influenced carbon source recovery, and mechanical elutriation could promote soluble COD (SCOD) and VFA yields. The optimal conditions of APT were SRT=5d, G=152s(-1) and RSR=10%, SCOD and VFA production were 57.0mg/L and 21.7mg/L. Particulate organic matter in sludge was converted into SCOD and VFAs as fermentative bacteria were significantly enriched in APT. Moreover, the APT process was applied in a wastewater treatment plant to solve the problem of insufficient carbon source. The outcomes demonstrated that influent SCOD of biological tank increased by 31.1%, which improved the efficiency of removing nitrogen and phosphorus.

  11. Biotechnological Production of Docosahexaenoic Acid Using Aurantiochytrium limacinum: Carbon Sources Comparison And Growth Characterization

    PubMed Central

    Abad, Sergi; Turon, Xavier

    2015-01-01

    Aurantiochytrium limacinum, a marine heterotrophic protist/microalga has shown interesting yields of docosahexaenoic acid (DHA) when cultured with different carbon sources: glucose, pure and crude glycerol. A complete study in a lab-scale fermenter allowed for the characterization and comparison of the growth kinetic parameters corresponding to each carbon source. Artificial Marine Medium (AMM) with glucose, pure and crude glycerol offered similar biomass yields. The net growth rates (0.10–0.12 h−1), biomass (0.7–0.8 g cells/g Substrate) and product (0.14–0.15 g DHA/g cells) yields, as well as DHA productivity were similar using the three carbon sources. Viable potential applications to valorize crude glycerol are envisioned to avoid an environmental problem due to the excess of byproduct. PMID:26690180

  12. Behavior of solid carbon sources for biological denitrification in groundwater remediation.

    PubMed

    Zhang, Jianmei; Feng, Chuanping; Hong, Siqi; Hao, Huiling; Yang, Yingnan

    2012-01-01

    The present study was conducted to compare the behavior of wheat straw, sawdust and biodegradable plastic (BP) as potential carbon sources for denitrification in groundwater remediation. The results showed that a greater amount of nitrogen compounds were released from wheat straw and sawdust than from BP in leaching experiments. In batch experiments, BP showed higher nitrate removal efficiency and longer service life than wheat straw and sawdust, which illustrated that BP is the most appropriate carbon source for stimulation of denitrification activity. In column experiments, BP was able to support complete denitrification at influent nitrate concentrations of 50, 60, 70, 80, and 90 mg NO(3)(-)-N/L, showing corresponding denitrification rates of 0.12, 0.14, 0.17, 0.19, and 0.22 mg NO(3)(-)-N.L(-1).d(-1).g(-1), respectively. These findings indicate that BP is applicable for use as a carbon source for nitrate-polluted groundwater remediation.

  13. Carbon Storages in Plantation Ecosystems in Sand Source Areas of North Beijing, China

    PubMed Central

    Liu, Xiuping; Zhang, Wanjun; Cao, Jiansheng; Shen, Huitao; Zeng, Xinhua; Yu, Zhiqiang; Zhao, Xin

    2013-01-01

    Afforestation is a mitigation option to reduce the increased atmospheric carbon dioxide levels as well as the predicted high possibility of climate change. In this paper, vegetation survey data, statistical database, National Forest Resource Inventory database, and allometric equations were used to estimate carbon density (carbon mass per hectare) and carbon storage, and identify the size and spatial distribution of forest carbon sinks in plantation ecosystems in sand source areas of north Beijing, China. From 2001 to the end of 2010, the forest areas increased more than 2.3 million ha, and total carbon storage in forest ecosystems was 173.02 Tg C, of which 82.80 percent was contained in soil in the top 0–100 cm layer. Younger forests have a large potential for enhancing carbon sequestration in terrestrial ecosystems than older ones. Regarding future afforestation efforts, it will be more effective to increase forest area and vegetation carbon density through selection of appropriate tree species and stand structure according to local climate and soil conditions, and application of proper forest management including land-shaping, artificial tending and fencing plantations. It would be also important to protect the organic carbon in surface soils during forest management. PMID:24349223

  14. Carbon storages in plantation ecosystems in sand source areas of north Beijing, China.

    PubMed

    Liu, Xiuping; Zhang, Wanjun; Cao, Jiansheng; Shen, Huitao; Zeng, Xinhua; Yu, Zhiqiang; Zhao, Xin

    2013-01-01

    Afforestation is a mitigation option to reduce the increased atmospheric carbon dioxide levels as well as the predicted high possibility of climate change. In this paper, vegetation survey data, statistical database, National Forest Resource Inventory database, and allometric equations were used to estimate carbon density (carbon mass per hectare) and carbon storage, and identify the size and spatial distribution of forest carbon sinks in plantation ecosystems in sand source areas of north Beijing, China. From 2001 to the end of 2010, the forest areas increased more than 2.3 million ha, and total carbon storage in forest ecosystems was 173.02 Tg C, of which 82.80 percent was contained in soil in the top 0-100 cm layer. Younger forests have a large potential for enhancing carbon sequestration in terrestrial ecosystems than older ones. Regarding future afforestation efforts, it will be more effective to increase forest area and vegetation carbon density through selection of appropriate tree species and stand structure according to local climate and soil conditions, and application of proper forest management including land-shaping, artificial tending and fencing plantations. It would be also important to protect the organic carbon in surface soils during forest management.

  15. Carbon Source Preference in Chemosynthetic Hot Spring Communities

    PubMed Central

    Urschel, Matthew R.; Kubo, Michael D.; Hoehler, Tori M.; Peters, John W.

    2015-01-01

    Rates of dissolved inorganic carbon (DIC), formate, and acetate mineralization and/or assimilation were determined in 13 high-temperature (>73°C) hot springs in Yellowstone National Park (YNP), Wyoming, in order to evaluate the relative importance of these substrates in supporting microbial metabolism. While 9 of the hot spring communities exhibited rates of DIC assimilation that were greater than those of formate and acetate assimilation, 2 exhibited rates of formate and/or acetate assimilation that exceeded those of DIC assimilation. Overall rates of DIC, formate, and acetate mineralization and assimilation were positively correlated with spring pH but showed little correlation with temperature. Communities sampled from hot springs with similar geochemistries generally exhibited similar rates of substrate transformation, as well as similar community compositions, as revealed by 16S rRNA gene-tagged sequencing. Amendment of microcosms with small (micromolar) amounts of formate suppressed DIC assimilation in short-term (<45-min) incubations, despite the presence of native DIC concentrations that exceeded those of added formate by 2 to 3 orders of magnitude. The concentration of added formate required to suppress DIC assimilation was similar to the affinity constant (Km) for formate transformation, as determined by community kinetic assays. These results suggest that dominant chemoautotrophs in high-temperature communities are facultatively autotrophic or mixotrophic, are adapted to fluctuating nutrient availabilities, and are capable of taking advantage of energy-rich organic substrates when they become available. PMID:25819970

  16. Innovative slow-release organic carbon-source material for groundwater in situ denitrification.

    PubMed

    Zhang, Dayi; Zhang, Xu; Wang, Yun; Zhou, Guizhong; Li, Guanghe

    2015-01-01

    Slow-release organic carbon-source (SOC) material, a new kind of electron donor for in situ groundwater denitrification, was prepared and evaluated in this study. With starch as a biologically utilized carbon source and polyvinyl alcohol (PVA) as a frame, this material performed controllable carbon release rates and demonstrated stable behaviour during the simulated denitrification process. Raman spectrum analysis showed that the PVA skeleton formed cross-linking network structures for hydrogen-bonded water molecules reset in low temperatures, and the starchy molecules filled in the interspace of the skeleton to form a two-phase interlocking/disperse phase structure. In a static system, carbon release processes followed the Fickian law with (1.294-6.560)×10(-3) mg g(-1) s(-1/2) as the release coefficient. Under domestication and in situ groundwater simulation conditions, SOC material played a favourable role during denitrification, with 1.049±0.165 as an average carbon-nitrogen ratio. The denitrification process followed the law of zero-order kinetics, while the dynamics parameter kN was 0.563-8.753 gN m(-3) d(-1). Generally, SOC material was suggested to be a potential carbon source (electron donor) suitable for in situ groundwater denitrification.

  17. Large-scale, near-field magnetic fields from external sources and the corresponding induced internal field

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Estes, R. H.

    1985-01-01

    Data from Magsat analyzed as a function of the Dst index to determine the first degree/order spherical harmonic description of the near-earth external field and its corresponding induced field. The analysis was done separately for data from dawn and dusk. The Magsat data was compared with POGO data. A local time variation of the external field persists even during very quiet magnetic conditions; both a diurnal and 8-hour period are present. A crude estimate of Sq current in the 45 deg geomagnetic latitude range is obtained for 1966 to 1970. The current strength, located in the ionosphere and induced in the earth, is typical of earlier determinations from surface data, although its maximum is displaced in local time from previous results.

  18. Large-scale, near-Earth, magnetic fields from external sources and the corresponding induced internal field

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Estes, R. H.

    1983-01-01

    Data from MAGSAT analyzed as a function of the Dst index to determine the first degree/order spherical harmonic description of the near-Earth external field and its corresponding induced field. The analysis was done separately for data from dawn and dusk. The MAGSAT data was compared with POGO data. A local time variation of the external field persists even during very quiet magnetic conditions; both a diurnal and 8-hour period are present. A crude estimate of Sq current in the 45 deg geomagnetic latitude range is obtained for 1966 to 1970. The current strength, located in the ionosphere and induced in the Earth, is typical of earlier determinations from surface data, although its maximum is displaced in local time from previous results.

  19. North America carbon dioxide sources and sinks: magnitude, attribution, and uncertainty

    SciTech Connect

    King, Anthony W.; Hayes, Daniel J.; Huntzinger, Deborah N.; West, Tristram O.; Post, W. M.

    2012-12-01

    North America is both a source and sink of atmospheric CO2. Sources, predominately fossil-fuel combustion in the United States along with contributions from deforestation in Mexico, add CO2 to the atmosphere. Most North America ecosystems, particularly regrowing forests in the United States, are sinks for atmospheric CO2. CO2 is removed from the atmosphere in photosynthesis, converted into biomass and stored as carbon in vegetation, soil and wood products. Fossil-fuel emissions dominate the North American source-sink balance. North America is a net source of atmospheric CO2 with ecosystem sinks balancing approximately 35% of fossil-fuel CO2 emissions from North America.

  20. Evaluation of natural materials as exogenous carbon sources for biological treatment of low carbon-to-nitrogen wastewater.

    PubMed

    Ramírez-Godínez, Juan; Beltrán-Hernández, Icela; Álvarez-Hernández, Alejandro; Coronel-Olivares, Claudia; Contreras-López, Elizabeth; Quezada-Cruz, Maribel; Vázquez-Rodríguez, Gabriela

    2015-01-01

    In the bacterial processes involved in the mitigation of nitrogen pollution, an adequately high carbon-to-nitrogen (C : N) ratio is key to sustain denitrification. We evaluated three natural materials (woodchips, barley grains, and peanut shells) as carbon sources for low C : N wastewater. The amount of organic matter released from these materials to aqueous media was evaluated, as well as their pollution swapping potential by measuring the release of total Kjeldahl nitrogen, N-NH4 (+), NO2 (-), and NO3 (-), and total phosphorous. Barley grains yielded the highest amount of organic matter, which also showed to be the most easily biodegradable. Woodchips and peanut shells released carbon rather steadily and so they would not require frequent replenishment from biological reactors. These materials produced eluates with lower concentrations of nutrients than the leachates from barley grains. However, as woodchips yielded lower amounts of suspended solids, they constitute an adequate exogenous source for the biological treatment of carbon-deficient effluents.

  1. Evaluation of Natural Materials as Exogenous Carbon Sources for Biological Treatment of Low Carbon-to-Nitrogen Wastewater

    PubMed Central

    Ramírez-Godínez, Juan; Beltrán-Hernández, Icela; Álvarez-Hernández, Alejandro; Coronel-Olivares, Claudia; Contreras-López, Elizabeth; Quezada-Cruz, Maribel; Vázquez-Rodríguez, Gabriela

    2015-01-01

    In the bacterial processes involved in the mitigation of nitrogen pollution, an adequately high carbon-to-nitrogen (C : N) ratio is key to sustain denitrification. We evaluated three natural materials (woodchips, barley grains, and peanut shells) as carbon sources for low C : N wastewater. The amount of organic matter released from these materials to aqueous media was evaluated, as well as their pollution swapping potential by measuring the release of total Kjeldahl nitrogen, N-NH4+, NO2−, and NO3−, and total phosphorous. Barley grains yielded the highest amount of organic matter, which also showed to be the most easily biodegradable. Woodchips and peanut shells released carbon rather steadily and so they would not require frequent replenishment from biological reactors. These materials produced eluates with lower concentrations of nutrients than the leachates from barley grains. However, as woodchips yielded lower amounts of suspended solids, they constitute an adequate exogenous source for the biological treatment of carbon-deficient effluents. PMID:26495313

  2. Bright, low debris, ultrashort hard x-ray table top source using carbon nanotubes

    SciTech Connect

    Bagchi, Suman; Kiran, P. Prem; Yang, K.; Rao, A. M.; Bhuyan, M. K.; Krishnamurthy, M.; Kumar, G. Ravindra

    2011-01-15

    We demonstrate that carbon nanotube coated surfaces produce two orders of magnitude brighter hard x-ray emission, in laser produced plasmas, than planar surfaces. It is accompanied by three orders of magnitude reduction in ion debris which is also low Z and nontoxic. The increased emission is a direct consequence of the enhancement in local fields and is via the simple and well known 'lightning rod' effect. We propose that this carbon nanotube hard x-ray source is a simple, inexpensive, and high repetition rate hard x-ray point source for a variety of applications in imaging, lithography, microscopy, and material processing.

  3. The effect of various carbon sources on the growth of single-celled cyanophyta

    NASA Technical Reports Server (NTRS)

    Avilov, I. A.; Sidorenkova, E. S.

    1983-01-01

    In 19 strains of unicellular blue-green algae, belonging to general Synechococcus, Synechocystis, Aphanocapsa and Aphanothece, the capacity of growth under mixotrophic conditions in mineral media with organic carbon sources (carbohydrates, polyols) was investigated. At moderate light intensity (1200 lx) and 0.5% of carbon source there was revealed: (1) Stimulation of growth; (2) Partial or complete inhibition of growth; (3) No influence of carbohydrate and polyols on the growth of some algae strains. Three physiological groups for the investigated strains have been outlined on the basis of data obtained. The possibility of using the differences revealed in classification of unicellular blue-green algae is discussed.

  4. Carbon nanotube based X-ray sources: Applications in pre-clinical and medical imaging

    NASA Astrophysics Data System (ADS)

    Lee, Yueh Z.; Burk, Laurel; Wang, Ko-Han; Cao, Guohua; Lu, Jianping; Zhou, Otto

    2011-08-01

    Field emission offers an alternate method of electron production for Bremsstrahlung based X-ray tubes. Carbon nanotubes (CNTs) serve as very effective field emitters, allowing them to serve as electron sources for X-ray sources, with specific advantages over traditional thermionic tubes. CNT derived X-ray sources can create X-ray pulses of any duration and frequency, gate the X-ray pulse to any source and allow the placement of many sources in close proximity.We have constructed a number of micro-CT systems based on CNT X-ray sources for applications in small animal imaging, specifically focused on the imaging of the heart and lungs. This paper offers a review of the pre-clinical applications of the CNT based micro-CT that we have developed. We also discuss some of the current and potential clinical applications of the CNT X-ray sources.

  5. An innovative wood-chip-framework substrate used as slow-release carbon source to treat high-strength nitrogen wastewater.

    PubMed

    Li, Huai; Chi, Zifang; Yan, Baixing; Cheng, Long; Li, Jianzheng

    2017-01-01

    Removal of nitrogen in wastewater before discharge into receiving water courses is an important consideration in treatment systems. However, nitrogen removal efficiency is usually limited due to the low carbon/nitrogen (C/N) ratio. A common solution is to add external carbon sources, but amount of liquid is difficult to determine. Therefore, a combined wood-chip-framework substrate (with wood, slag and gravel) as a slow-release carbon source was constructed in baffled subsurface-flow constructed wetlands to overcome the problem. Results show that the removal rate of ammonia nitrogen (NH4(+)-N), total nitrogen (TN) and chemical oxygen demand (COD) could reach 37.5%-85%, 57.4%-86%, 32.4%-78%, respectively, indicating the combined substrate could diffuse sufficient oxygen for the nitrification process (slag and gravel zone) and provide carbon source for denitrification process (wood-chip zone). The nitrification and denitrification were determined according to the location of slag/gravel and wood-chip, respectively. Nitrogen removal was efficient at the steady phase before a shock loading using slag-wood-gravel combined substrate because of nitrification-denitrification process, while nitrogen removal was efficient under a shock loading with wood-slag-gravel combined substrate because of ANAMMOX process. This study provides a new idea for wetland treatment of high-strength nitrogen wastewater.

  6. CO2 mitigation potential of mineral carbonation with industrial alkalinity sources in the United States.

    PubMed

    Kirchofer, Abby; Becker, Austin; Brandt, Adam; Wilcox, Jennifer

    2013-07-02

    The availability of industrial alkalinity sources is investigated to determine their potential for the simultaneous capture and sequestration of CO2 from point-source emissions in the United States. Industrial alkalinity sources investigated include fly ash, cement kiln dust, and iron and steel slag. Their feasibility for mineral carbonation is determined by their relative abundance for CO2 reactivity and their proximity to point-source CO2 emissions. In addition, the available aggregate markets are investigated as possible sinks for mineral carbonation products. We show that in the U.S., industrial alkaline byproducts have the potential to mitigate approximately 7.6 Mt CO2/yr, of which 7.0 Mt CO2/yr are CO2 captured through mineral carbonation and 0.6 Mt CO2/yr are CO2 emissions avoided through reuse as synthetic aggregate (replacing sand and gravel). The emission reductions represent a small share (i.e., 0.1%) of total U.S. CO2 emissions; however, industrial byproducts may represent comparatively low-cost methods for the advancement of mineral carbonation technologies, which may be extended to more abundant yet expensive natural alkalinity sources.

  7. Carbon isotope based aerosol source apportionment in Eastern European city Vilnius

    NASA Astrophysics Data System (ADS)

    Garbaras, Andrius; Sapolaite, Justina; Garbariene, Inga; Ezerinskis, Zilvinas; Pocevicius, Matas; Krikscikas, Laurynas; Jacevicius, Sarunas; Plukis, Arturas; Remeikis, Vidmantas

    2016-04-01

    We present carbonaceous aerosol source apportionment results in Eastern European city Vilnius (capital of Lithuania) using stable carbon isotope ratio (δ13C) and radiocarbon (14C) methods. The aerosol sampling campaigns were performed in 2014-2016 winter seasons in Vilnius. PM1 particles were collected on quartz fiber filters using high volume sampler, while PM10 and size segregated aerosol particles were collected using low volume and MOUDI 128 cascade impactor respectively. δ13C values were measured with EA-IRMS system while radiocarbon analysis was performed using Single Stage Accelerator Mass Spectrometer (SSAMS). For the AMS analysis, filters (or aluminium foils from cascade impactor) were graphitized using Automated Graphitization Equipment. It was estimated that dominant carbonaceous aerosol source in Vilnius was of biogenic/biomass origin (60-90 %). Fossil fuel sources accounted for up to 23 % of total carbon fraction. Combining stable carbon and radiocarbon isotope analysis we were able to quantify the amount of coal derived aerosol particles. The contribution of coal burning emissions were up to 14 %. We will present the applicability of dual carbon (13C and 14C) isotope ratio method for the aerosol source apportionment in different regions of Europe, also the perspectives of using MOUDI cascade impactors to make source apportionment in size segregated aerosol particles.

  8. Novel Molecular Sources for Dispersing Boron in Carbon-Carbon Composites.

    DTIC Science & Technology

    1993-11-07

    moisture affinity of the boria seriously affects composite performance. Substitution of furfuryl and pitch as the resin precursors significantly improved...addition to a commercial furfuryl /pitch blend (Kaiser Code88A) yielded a carbon char with reduced moisture affinity and improved oxidation resistance

  9. Carbon allocation, source-sink relations and plant growth: do we need to revise our carbon centric concepts?

    NASA Astrophysics Data System (ADS)

    Körner, Christian

    2014-05-01

    Since the discovery that plants 'eat air' 215 years ago, carbon supply was considered the largely unquestioned top driver of plant growth. The ease at which CO2 uptake (C source activity) can be measured, and the elegant algorithms that describe the responses of photosynthesis to light, temperature and CO2 concentration, explain why carbon driven growth and productivity became the starting point of all process based vegetation models. Most of these models, nowadays adopt other environmental drivers, such as nutrient availability, as modulating co-controls, but the carbon priority is retained. Yet, if we believe in the basic rules of stoichometry of all life, there is an inevitable need of 25-30 elements other then carbon, oxygen and hydrogen to build a healthy plant body. Plants compete for most of these elements, and their availability (except for N) is finite per unit land area. Hence, by pure plausibility, it is a highly unlikely situation that carbon plays the rate limiting role of growth under natural conditions, except in deep shade or on exceptionally fertile soils. Furthermore, water shortage and low temperature, both act directly upon tissue formation (meristems) long before photosynthetic limitations come into play. Hence, plants will incorporate C only to the extent other environmental drivers permit. In the case of nutrients and mature ecosystems, this sink control of plant growth may be masked in the short term by a tight, almost closed nutrient cycle or by widening the C to other element ratio. Because source and sink activity must match in the long term, it is not possible to identify the hierarchy of growth controls without manipulating the environment. Dry matter allocation to C rich structures and reserves may provide some stoichimetric leeway or periodic escapes from the more fundamental, long-term environmental controls of growth and productivity. I will explain why carbon centric explanations of growth are limited or arrive at plausible answers

  10. Immune response and disease resistance of shrimp fed biofloc grown on different carbon sources.

    PubMed

    Ekasari, Julie; Hanif Azhar, Muhammad; Surawidjaja, Enang H; Nuryati, Sri; De Schryver, Peter; Bossier, Peter

    2014-12-01

    The objective of this study was to document the immunological effects of growing shrimp in biofloc systems. The experiment consisted of four types of biofloc systems in which bioflocs were produced by daily supplementation of four different carbon sources, i.e. molasses, tapioca, tapioca-by-product, and rice bran, at an estimated C/N ratio of 15 and a control system without any organic carbon addition. Each biofloc system was stocked with Pacific white shrimp (Litopenaeus vannamei) juveniles that were reared for 49 days. The use of tapioca-by-product resulted in a higher survival (93%) of the shrimp as compared to the other carbon sources and the control. The highest yield and protein assimilation was observed when tapioca was used as the carbon source. After 49 days, phenoloxidase (PO) activity of the shrimp grown in all biofloc systems was higher than that of the shrimp from the control system. Following a challenge test by injection with infectious myonecrosis virus (IMNV), the levels of PO and respiratory burst (RB) activity in the shrimp of all biofloc treatments were higher than that of the challenged shrimp from the control treatment. An increased immunity was also suggested by the survival of the challenged shrimp from the experimental biofloc groups that was significantly higher as compared to the challenged shrimp from the control treatment, regardless of the organic carbon source used to grow the bioflocs. Overall, this study demonstrated that the application of biofloc technology may contribute to the robustness of cultured shrimp by immunostimulation and that this effect is independent of the type of carbon source used to grow the flocs.

  11. Methods of analysis for complex organic aerosol mixtures from urban emission sources of particulate carbon

    SciTech Connect

    Mazurek, M.A. ); Hildemann, L.M. . Dept. of Civil Engineering); Cass, G.R.; Rogge, W.F. . Dept. of Environmental Engineering Science); Simoneit, B.R.T. . Coll. of Oceanography)

    1990-04-01

    Extractable organic compounds having between 6 to 40 carbon atoms comprise an important mass fraction of the fine particulate matter samples from major urban emission sources. Depending on the emission source type, this solvent-soluble fraction accounts for <20% to 100% of the total organic aerosol mass, as measured by quantitative high-resolution has chromatography (HRGC) with flame ionization detection. In addition to total extract quantitation, HRGC can be applied to further analyses of the mass distributions of elutable organics present in the complex aerosol extract mixtures, thus generating profiles that serve as fingerprints'' for the sources of interest. This HRGC analytical method is applied to emission source samples that contain between 7 to 12,000 {mu}g/filter organic carbon. It is shown to be a sensitive technique for analysis of carbonaceous aerosol extract mixtures having diverse mass loadings and species distributions. This study describes the analytical chemical methods that have been applied to: the construction of chemical mass balances based on the mass of fine organic aerosol emitted for major urban sources of particulate carbon; and the generation of discrete emission source chemical profiles derived from chromatographic characteristics of the organic aerosol components. 21 refs., 1 fig., 2 tabs.

  12. A Carbon Nano Tube electron impact ionisation source for low-power, compact spacecraft mass spectrometers

    NASA Astrophysics Data System (ADS)

    Sheridan, S.; Bardwell, M. W.; Morse, A. D.; Morgan, G. H.

    2012-04-01

    A novel ionisation source which uses commercially available Carbon Nano Tube devices is demonstrated as a replacement for a filament based ionisation source in an ion trap mass spectrometer. The carbon nanotube ion source electron emission was characterised and exhibited typical emission of 30 ± 1.7 μA with an applied voltage differential of 300 V between the carbon nanotube tips and the extraction grid. The ion source was tested for longevity and operated under a condition of continuous emission for a period of 44 h; there was an observed reduction in emission current of 26.5% during operation. Spectra were generated by installing the ion source into a Finnigan Mat ITD700 ion trap mass spectrometer; the spectra recorded showed all of the characteristic m/z peaks from m/z 69 to m/z 219. Perfluorotributylamine spectra were collected and averaged contiguously for a period of 48 h with no significant signal loss or peak mass allocation shift. The low power requirements and low mass of this novel ionisation source are considered be of great value to future space missions where mass spectrometric technology will be employed.

  13. Important fossil source contribution to brown carbon in Beijing during winter

    PubMed Central

    Yan, Caiqing; Zheng, Mei; Bosch, Carme; Andersson, August; Desyaterik, Yury; Sullivan, Amy P.; Collett, Jeffrey L.; Zhao, Bin; Wang, Shuxiao; He, Kebin; Gustafsson, Örjan

    2017-01-01

    Organic aerosol (OA) constitutes a substantial fraction of fine particles and affects both human health and climate. It is becoming clear that OA absorbs light substantially (hence termed Brown Carbon, BrC), adding uncertainties to global aerosol radiative forcing estimations. The few current radiative-transfer and chemical-transport models that include BrC primarily consider sources from biogenic and biomass combustion. However, radiocarbon fingerprinting here clearly indicates that light-absorbing organic carbon in winter Beijing, the capital of China, is mainly due to fossil sources, which contribute the largest part to organic carbon (OC, 67 ± 3%) and its sub-constituents (water-soluble OC, WSOC: 54 ± 4%, and water-insoluble OC, WIOC: 73 ± 3%). The dual-isotope (Δ14C/δ13C) signatures, organic molecular tracers and Beijing-tailored emission inventory identify that this fossil source is primarily from coal combustion activities in winter, especially from the residential sector. Source testing on Chinese residential coal combustion provides direct evidence that intensive coal combustion could contribute to increased light-absorptivity of ambient BrC in Beijing winter. Coal combustion is an important source to BrC in regions such as northern China, especially during the winter season. Future modeling of OA radiative forcing should consider the importance of both biomass and fossil sources. PMID:28266611

  14. Important fossil source contribution to brown carbon in Beijing during winter

    NASA Astrophysics Data System (ADS)

    Yan, Caiqing; Zheng, Mei; Bosch, Carme; Andersson, August; Desyaterik, Yury; Sullivan, Amy P.; Collett, Jeffrey L.; Zhao, Bin; Wang, Shuxiao; He, Kebin; Gustafsson, Örjan

    2017-03-01

    Organic aerosol (OA) constitutes a substantial fraction of fine particles and affects both human health and climate. It is becoming clear that OA absorbs light substantially (hence termed Brown Carbon, BrC), adding uncertainties to global aerosol radiative forcing estimations. The few current radiative-transfer and chemical-transport models that include BrC primarily consider sources from biogenic and biomass combustion. However, radiocarbon fingerprinting here clearly indicates that light-absorbing organic carbon in winter Beijing, the capital of China, is mainly due to fossil sources, which contribute the largest part to organic carbon (OC, 67 ± 3%) and its sub-constituents (water-soluble OC, WSOC: 54 ± 4%, and water-insoluble OC, WIOC: 73 ± 3%). The dual-isotope (Δ14C/δ13C) signatures, organic molecular tracers and Beijing-tailored emission inventory identify that this fossil source is primarily from coal combustion activities in winter, especially from the residential sector. Source testing on Chinese residential coal combustion provides direct evidence that intensive coal combustion could contribute to increased light-absorptivity of ambient BrC in Beijing winter. Coal combustion is an important source to BrC in regions such as northern China, especially during the winter season. Future modeling of OA radiative forcing should consider the importance of both biomass and fossil sources.

  15. Evaluating North Sea carbon sources using radiogenic (224Ra and 228Ra) and stable carbon isotope (DI13C) tracers

    NASA Astrophysics Data System (ADS)

    Burt, William; Thomas, Helmuth; Hagens, Mathilde; Brenner, Heiko; Paetsch, Johannes; Clargo, Nikki

    2015-04-01

    In the North Sea, much uncertainty still exists regarding the role of boundary fluxes (e.g. benthic input from sediments or lateral inputs from the coastline) in the overall biogeochemical cycling of the system. The stable carbon isotope signature of dissolved inorganic carbon (δ13C-DIC) is a common tool for following transformations of carbon in the water column and identifying carbon sources and sinks. Here, analyses of the first basin-wide observations of δ13C-DIC reveal that a balance between biological production and respiration, as well as a freshwater input near the European continental coast, predominantly control surface distributions in the North Sea. A strong relationship between the biological component of DIC (DICbio) and δ13C-DIC is then used to quantify the metabolic DIC flux associated with changes in the carbon isotopic signature. Correlations are also found between δ13C-DIC and naturally-occurring Radium isotopes (224Ra and 228Ra), which have well-identified sources from the seafloor and coastal boundaries. The relationship between δ13C-DIC and the longer-lived 228Ra isotope (half-life = 5.8 years) is used to derive a metabolic DIC flux from the European continental coastline. 228Ra is also shown to be a highly effective tracer of North Sea total alkalinity (TA) compared to the more conventional use of salinity as a tracer. Coastal alkalinity inputs are calculated using relationships with 228Ra, and ratios of DIC and TA suggest denitrification as the main metabolic pathway for the formation of these coastal inputs. Finally, coastal TA inputs are translated into inputs of protons to quantify their impact on the buffering capacity of the Southern North Sea.

  16. Optimizing the weight loss-on-ignition methodology to quantify organic and carbonate carbon of sediments from diverse sources.

    PubMed

    Wang, Qingren; Li, Yuncong; Wang, Y

    2011-03-01

    The sequential weight loss-on-ignition (WLOI) method for determination of organic and carbonate or inorganic carbon (C) content was evaluated on sediments from diverse sources with a great range of C contents. The sediments were collected from canal, wetland, river, estuary, lake, and marine sites. The organic and inorganic C contents of these samples ranged from 1 to 430 g kg( -1) and from 4 to 97 g kg( -1), respectively. Combinations of the combustion time and temperature and optimal weight ranges of representative samples were tested, and comparisons of the WLOI method with other methods, including dry combustion and wet combustion, were made. These methods were (1) use of the carbon-nitrogen-sulfur (CNS) autoanalyzer with normal and reduced temperatures for total and organic C, (2) thermogravimetry for both organic and inorganic C, (3) use of the CNS autoanalyzer after removal of inorganic (carbonate) C by fumigating samples with concentrated HCl for organic C, (4) Walkley-Black wet combustion method for organic C, and (5) pressure-calcimeter associated with subtraction method (total C minus inorganic C) for organic C determinations. The results of analyzing samples of sediments of diverse origins showed that the optimal combination of temperature and time of WLOI depended mostly on the sources of the analyzed sediment. The WLOI analysis of sediment samples for organic C from wetlands, canal, estuary, or river sites needed a relatively low temperature but that of sediment samples from lake and marine sites required a relatively high temperature. Overall, to obtain reliable analysis results of samples from widely varied sediment sources except marine sediments, 500°C for 12 h was optimal for organic C content determination, and 800°C for yet another 12 h was optimal for inorganic C content determination. The temperature could even be reduced to 475°C if only wetland and stream sediments were included, but for marine sediments, 550°C for 12 h was

  17. Simulating Geomagnetic Depth Sounding using a Time-domain Finite Element Method: Effects of Asymmetric External Source Fields

    NASA Astrophysics Data System (ADS)

    Ribaudo, J. T.; Constable, C.

    2010-12-01

    The commercial finite element software FlexPDE has been successfully used to simulate electromagnetic induction in Earth's mantle and lithosphere and validated by several previously published results. Estimates of Earth's frequency-dependent electromagnetic response calculated from satellite data are known to be influenced by the local time of the observing frame. We use time-stepping methods scripted within FlexPDE to investigate the hypothesis that this bias results from the rotation of Earth through the asymmetric and highly variable magnetic field associated with the magnetospheric ring current. We evaluate local-time response functions at periods of a few hours to a few months. These are calculated from long 3-dimensional, time-domain simulations of geomagnetic induction and using the magnetic data similar to those gathered by low earth orbiting satellite missions. The spatial structure of the external field is imposed in the form of a time-varying spherical harmonic representation in a geomagnetic coordinate system that rotates with respect to Earth. The symmetric part of the field is controlled by the dipole (degree 1, order 0) term and the asymmetric part controlled by a quadrupole (degree 2, order 1) term. Time variations in the magnitude of the external field are controlled by a high-resolution magnetic index such as the new 1-minute USGS Dst, subsampled at 15 minute intervals.

  18. Effect of geological carbon sources on eddy covariance measurements: analysis and possible correction approaches

    NASA Astrophysics Data System (ADS)

    Papale, D.; Rey, A.; Belelli-Marchesini, L.; Etiope, G.; Pegoraro, E.

    2013-12-01

    A recent set of studies carried out in the SE of Spain highlighted the need to consider geological carbon sources when estimating the net ecosystem carbon balance (NECB) of terrestrial ecosystems located in areas potentially affected by geofluid circulation. In this study we present the mechanisms and propose a new methodology using physical parameters of the atmospheric boundary layer to quantify the CO2 coming from deep origin. To test our approach, we compare NECB estimates with seasonal patterns of soil CO2 efflux and vegetation activity measured by satellite images (NDVI) over two-year period at this site (2007/2008). According with the eddy covariance measurements the alpha grass ecosystem was a net carbon source (93.7 and 145.0 g C m-2, for the years 2007 and 2008, respectively) particularly as a result of large amounts of carbon released over the dry period. This relevant CO2 emission (reaching up to 15 umol m-2 s-1) was however not related to ecosystem activities as confirmed by measurements of soil CO2 efflux using chambers (ca. 0.5 umol m-2 s-1) and plant productivity that was minimal during this period. A simple correction based on a linear relationship between NECB and wind speed for different stability conditions and wind sectors has been used to estimate the geological flux FGEO and subtracted it from the NECB to obtain the biological flux FBIO. We then partitioned FBIO into gross primary productivity and ecosystem respiration and proved that, after removing FGEO, ecosystem and soil respiration followed similar temporal patterns. The annual contribution of the geological component to NECB was 49.6 and 46.7 % for the year 2007 and 2008, respectively. Therefore, potential contribution of geological carbon sources should be tested and quantified in those ecosystems located in areas with potential natural emission of geologic gases to the surface. References: REY A., BELELLI MARCHESINI L., WERE A., SERRANO ORTIZ P., ETIOPE G., PAPALE D, DOMINGO F

  19. Enhanced primary sludge sonication by heat insulation to reclaim carbon source for biological phosphorous removal.

    PubMed

    Tian, Qing; Wang, Qi; Zhu, Yanbing; Li, Fang; Zhuang, Lin; Yang, Bo

    2017-01-01

    Ultrasound pretreatment is a potent step to disintegrate primary sludge (PS). The supernatant of sonicated PS is recycled as an alternative carbon source for biological phosphorus removal. In this study, we investigated the role of temperature on PS disintegration during sonication. We found that a temperature of 60°C yielded a dissolution rate of about 2% soluble chemical oxygen demand (SCOD) as compared to 7% SCOD using sonication at the specific energy (SE) of 7359kJ/kg TS. Using the SE of 6000kJ/kg TS with heat insulation during sonication, the SCOD dissolution rate of PS was similar to the result at the SE of 7051kJ/kg TS without heat insulation. Upon treatment with sonication, the PS released low concentrations of Cu and Zn into the supernatant. The phosphorus-accumulating organisms (PAOs) used the supernatant of sonicated PS as the carbon source. Supplementation with the diluted sonicated PS supernatant (SCOD≈1000mg/L) in anaerobic phase resulted in the release of phosphorus (36mg/L) and the production of polyhydroxyalkanoates (PHAs) (0.36g PHA/g SS). Compared with sodium acetate, higher polyhydroxyvalerate (PHV) faction in the polyhydroxyalkanoates (PHAs) was observed in the biomass when incubated with sonicated PS as the carbon source. This work provides a simple pathway to conserve energy and to enhance efficiencies of ultrasonic pretreatment and the recovery of carbon source from the sludge for improving the phosphorus removal in the ENR system.

  20. Proteome-wide quantitative multiplexed profiling of protein expression: carbon-source dependency in Saccharomyces cerevisiae

    PubMed Central

    Paulo, Joao A.; O’Connell, Jeremy D.; Gaun, Aleksandr; Gygi, Steven P.

    2015-01-01

    The global proteomic alterations in the budding yeast Saccharomyces cerevisiae due to differences in carbon sources can be comprehensively examined using mass spectrometry–based multiplexing strategies. In this study, we investigate changes in the S. cerevisiae proteome resulting from cultures grown in minimal media using galactose, glucose, or raffinose as the carbon source. We used a tandem mass tag 9-plex strategy to determine alterations in relative protein abundance due to a particular carbon source, in triplicate, thereby permitting subsequent statistical analyses. We quantified more than 4700 proteins across all nine samples; 1003 proteins demonstrated statistically significant differences in abundance in at least one condition. The majority of altered proteins were classified as functioning in metabolic processes and as having cellular origins of plasma membrane and mitochondria. In contrast, proteins remaining relatively unchanged in abundance included those having nucleic acid–related processes, such as transcription and RNA processing. In addition, the comprehensiveness of the data set enabled the analysis of subsets of functionally related proteins, such as phosphatases, kinases, and transcription factors. As a resource, these data can be mined further in efforts to understand better the roles of carbon source fermentation in yeast metabolic pathways and the alterations observed therein, potentially for industrial applications, such as biofuel feedstock production. PMID:26399295

  1. Influence of carbon source amendment on effectiveness of anaerobic soil disinfestation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic soil disinfestation (ASD; also termed biological soil disinfestation or soil reductive sterilization) is a non-chemical soil disinfestation process which includes 1) soil incorporation of a labile carbon (C) source, 2) mulching with a polyethylene film to limit gas exchange, and 3) drip ir...

  2. FOREST HARVESTS AND WOOD PRODUCTS: SOURCES AND SINKS OF ATMOSPHERIC CARBON DIOXIDE

    EPA Science Inventory

    Changes in the net carbon(c)sink-source balance related to a country's forest harvesting and use of wood products is an important component in making country-level inventories of greenhouse gas emissions,a current activity within many signatory nations to the UN Framework Convent...

  3. Carbon source and irrigation evaluation for anaerobic soil disinfestation in southern California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water use efficiency and utilization of feasible carbon sources have been important factors for successful implementation and adoption of ASD in California and are the focus of current research. In the 2014-15 study at Santa Paula, CA we compared ASD with 9 t of rice bran bed-incorporated with eith...

  4. SOURCE APPORTIONMENT OF SEATTLE PM 2.5 USING STN ORGANIC CARBON PEAKS

    EPA Science Inventory

    Results from the Source Apportionment of Seattle PM2.5 Using STN Organic Carbon Peaks study will be presented at the American Association for Aerosol Research (AAAR) 24th Annual Conference in Austin, Texas (Oct 17 - 21, 2005). Receptor modeling results from Seattle us...

  5. Silica-Based Carbon Source Delivery for In-situ Bioremediation Enhancement

    NASA Astrophysics Data System (ADS)

    Zhong, L.; Lee, M. H.; Lee, B.; Yang, S.

    2015-12-01

    Colloidal silica aqueous suspensions undergo viscosity increasing and gelation over time under favorable geochemical conditions. This property of silica suspension can potentially be applied to deliver remedial amendments to the subsurface and establish slow release amendment sources for enhanced remediation. In this study, silica-based delivery of carbon sources for in-situ bioremediation enhancement is investigated. Sodium lactate, vegetable oil, ethanol, and molasses have been studied for the interaction with colloidal silica in aqueous suspensions. The rheological properties of the carbon source amendments and silica suspension have been investigated. The lactate-, ethanol-, and molasses-silica suspensions exhibited controllable viscosity increase and eventually became gels under favorable geochemical conditions. The gelation rate was a function of the concentration of silica, salinity, amendment, and temperature. The vegetable oil-silica suspensions increased viscosity immediately upon mixing, but did not perform gelation. The carbon source release rate from the lactate-, ethanol-, and molasses-silica gels was determined as a function of silica, salinity, amendment concentration. The microbial activity stimulation and in-situ bioremediation enhancement by the slow-released carbon from the amendment-silica gels will be demonstrated in future investigations planned in this study.

  6. Impacts of carbon source addition on denitrification and phosphorus uptake in enhanced biological phosphorus removal systems.

    PubMed

    Begum, Shamim A; Batista, Jacimaria R

    2013-01-01

    In this study, simultaneous denitrification and phosphorus (P) removal were investigated in batch tests using nitrified mixed liquor and secondary wastewater influent from a full-scale treatment plant and different levels of acetate and propionate as supplemental carbon sources. Without supplemental carbon source, denitrification occurred at low rate and P release and P uptake was negatively affected (i.e., P removal of only 59.7%). When acetate and propionate were supplied, denitrification and P release occurred simultaneously under anoxic conditions. For acetate and propionate at a C/N stoichiometric ratio of 7.6, P release was negatively affected by denitrification. For acetate, the percent P removal and denitrification were very similar for C/N ratios of 22 (5X stoichiometric) and 59 (10X stoichiometric). For propionate, both percent P removal and denitrification deteriorated for C/N ratios of 22 (5X stoichiometric) and 45 (10X stoichiometric). It was observed that carbon source added in excess to stoichiometric ratio was consumed in the aerobic zone, but P was not taken up. This implies that PAO bacteria may utilize the excess carbon source in the aerobic zone rather than their polyhydroxyalkanoate (PHA) reserves, thereby promoting deterioration of the system.

  7. Proteome-wide quantitative multiplexed profiling of protein expression: carbon-source dependency in Saccharomyces cerevisiae.

    PubMed

    Paulo, Joao A; O'Connell, Jeremy D; Gaun, Aleksandr; Gygi, Steven P

    2015-11-05

    The global proteomic alterations in the budding yeast Saccharomyces cerevisiae due to differences in carbon sources can be comprehensively examined using mass spectrometry-based multiplexing strategies. In this study, we investigate changes in the S. cerevisiae proteome resulting from cultures grown in minimal media using galactose, glucose, or raffinose as the carbon source. We used a tandem mass tag 9-plex strategy to determine alterations in relative protein abundance due to a particular carbon source, in triplicate, thereby permitting subsequent statistical analyses. We quantified more than 4700 proteins across all nine samples; 1003 proteins demonstrated statistically significant differences in abundance in at least one condition. The majority of altered proteins were classified as functioning in metabolic processes and as having cellular origins of plasma membrane and mitochondria. In contrast, proteins remaining relatively unchanged in abundance included those having nucleic acid-related processes, such as transcription and RNA processing. In addition, the comprehensiveness of the data set enabled the analysis of subsets of functionally related proteins, such as phosphatases, kinases, and transcription factors. As a resource, these data can be mined further in efforts to understand better the roles of carbon source fermentation in yeast metabolic pathways and the alterations observed therein, potentially for industrial applications, such as biofuel feedstock production.

  8. The effect of alternating influent carbon source composition on activated sludge bioflocculation.

    PubMed

    Van Dierdonck, J; Van den Broeck, R; Vervoort, E; Van Impe, J; Smets, I

    2013-09-10

    The impact of alternating influent carbon sources, i.e., glucose and starch, on activated sludge bioflocculation was investigated. To this end, four lab-scale reactors were operated during a long-term experiment. During this period the influent carbon source ratio (glucose/starch) was alternated every 7 or 35 days (i.e., a fast and slow switching frequency). Bioflocculation was monitored throughout the entire experiment using an extensive set of parameters, including macroscopic and microscopic activated sludge characteristics. Sludge hydrophobicity remained high (>80%) throughout the experiment indicating good bioflocculation. However, sludge settleability decreased for all four reactors after a 60 day adaptation period to the applied alternation in influent carbon source. During this adaptation period, floc size decreased due to the release of microcolonies. The subsequent period was characterized by a decrease in settleability, coinciding with a release of primary particles and an increase in floc size. The observed phenomena could be linked with the protein concentration near the floc surface. This fraction mainly consists of hydrolytic enzymes necessary for the degradation of starch and is responsible for a progressive deterioration of the EPS matrix. The results of this specific study indicate to be independent of the influent carbon source ratio or switching frequency.

  9. PCDD/F FORMATION RATES FROM FLY ASH AND METHANE COMBUSTION CARBON SOURCES

    EPA Science Inventory

    The abstract discusses polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD,F) from fly ash and methane combustion carbon sources. (NOTE: PCDD,Fs are formed in trace quantities in combustion processes via two primary mechanisms: de novo synthesis in which they ...

  10. BACTERIOPLANKTON DYNAMICS IN PENSACOLA BAY, FL, USA: ROLE OF PHYTOPLANKTON AND DETRIAL CARBON SOURCES

    EPA Science Inventory

    Bacterioplankton Dynamics in Pensacola Bay, FL, USA: Role of Phytoplankton and Detrital Carbon Sources (Abstract). To be presented at the16th Biennial Conference of the Estuarine Research Foundation, ERF 2001: An Estuarine Odyssey, 4-8 November 2001, St. Pete Beach, FL. 1 p. (ER...

  11. Stream restoration and sewers impact sources and fluxes of water,carbon, and nutrients in urban watersheds

    EPA Science Inventory

    An improved understanding of sources and timing of water and nutrient fluxes associated with urban stream restoration is critical for guiding effective watershed management. We investigated how sources, fluxes, and flowpaths of water, carbon (C), nitrogen (N), and phosphorus (P)...

  12. Relative Contributions of Fossil and Contemporary Carbon sources to PM 2.5 Aerosols at Nine IMPROVE Network Sites

    SciTech Connect

    Bench, G; Fallon, S; Schichtel, B; Malm, W; McDade, C

    2006-06-26

    Particulate matter aerosols contribute to haze diminishing vistas and scenery at National Parks and Wilderness Areas within the United States. To increase understanding of the sources of carbonaceous aerosols at these settings, the total carbon loading and {sup 14}C/C ratio of PM 2.5 aerosols at nine IMPROVE (Interagency Monitoring for Protection Of Visual Environments) network sites were measured. Aerosols were collected weekly in the summer and winter at one rural site, two urban sites, five sites located in National Parks and one site located in a Wildlife Preserve. The carbon measurements together with the absence of {sup 14}C in fossil carbon materials and the known {sup 14}C/C levels in contemporary carbon materials were used to derive contemporary and fossil carbon contents of the particulate matter. Contemporary and fossil carbon aerosol loadings varied across the sites and suggest different percentages of carbon source inputs. The urban sites had the highest fossil carbon loadings that comprised around 50% of the total carbon aerosol loading. The Wildlife Preserve and National Park sites together with the rural site had much lower fossil carbon loading components. At these sites, variations in the total carbon aerosol loading were dominated by non-fossil carbon sources. This suggests that reduction of anthroprogenic sources of fossil carbon aerosols may result in little decrease in carbonaceous aerosol loading at many National Parks and rural areas.

  13. Enhanced light absorption by mixed source black and brown carbon particles in UK winter

    PubMed Central

    Liu, Shang; Aiken, Allison C.; Gorkowski, Kyle; Dubey, Manvendra K.; Cappa, Christopher D.; Williams, Leah R.; Herndon, Scott C.; Massoli, Paola; Fortner, Edward C.; Chhabra, Puneet S.; Brooks, William A.; Onasch, Timothy B.; Jayne, John T.; Worsnop, Douglas R.; China, Swarup; Sharma, Noopur; Mazzoleni, Claudio; Xu, Lu; Ng, Nga L.; Liu, Dantong; Allan, James D.; Lee, James D.; Fleming, Zoë L.; Mohr, Claudia; Zotter, Peter; Szidat, Sönke; Prévôt, André S. H.

    2015-01-01

    Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models. PMID:26419204

  14. Free nitrous acid pretreatment of wasted activated sludge to exploit internal carbon source for enhanced denitrification.

    PubMed

    Ma, Bin; Peng, Yongzhen; Wei, Yan; Li, Baikun; Bao, Peng; Wang, Yayi

    2015-03-01

    Using internal carbon source contained in waste activated sludge (WAS) is beneficial for nitrogen removal from wastewater with low carbon/nitrogen ratio, but it is usually limited by sludge disintegration. This study presented a novel strategy based on free nitrous acid (FNA) pretreatment to intensify the release of organic matters from WAS for enhanced denitrification. During FNA pretreatment, soluble chemical oxygen demand (SCOD) production kept increasing when FNA increased from 0 to 2.04 mg HNO2-N/L. Compared with untreated WAS, the internal carbon source production increased by 50% in a simultaneous fermentation and denitrification reactor fed with WAS pretreated by FNA for 24 h at 2.04 mg HNO2-N/L. This also increased denitrification efficiency by 76% and sludge reduction by 87.5%. More importantly, greenhouse gas nitrous oxide production in denitrification was alleviated since more electrons could be provided by FNA pretreated WAS.

  15. Enhanced light absorption by mixed source black and brown carbon particles in UK winter.

    PubMed

    Liu, Shang; Aiken, Allison C; Gorkowski, Kyle; Dubey, Manvendra K; Cappa, Christopher D; Williams, Leah R; Herndon, Scott C; Massoli, Paola; Fortner, Edward C; Chhabra, Puneet S; Brooks, William A; Onasch, Timothy B; Jayne, John T; Worsnop, Douglas R; China, Swarup; Sharma, Noopur; Mazzoleni, Claudio; Xu, Lu; Ng, Nga L; Liu, Dantong; Allan, James D; Lee, James D; Fleming, Zoë L; Mohr, Claudia; Zotter, Peter; Szidat, Sönke; Prévôt, André S H

    2015-09-30

    Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.

  16. Can we afford to waste carbon dioxide? Carbon dioxide as a valuable source of carbon for the production of light olefins.

    PubMed

    Centi, Gabriele; Iaquaniello, Gaetano; Perathoner, Siglinda

    2011-09-19

    Concerns about climate change have increased the amount of activity on carbon capture and sequestration (CCS) as one of the solutions to the problem of rising levels of CO(2) in the troposphere, while the reuse of CO(2) (carbon capture and recycling; CCR) has only recently received more attention. CCR is focused on the possibility of using CO(2) as a cheap (or even negative-value) raw material. This Concept paper analyzes this possibility from a different perspective: In a sustainable vision, can we afford to waste CO(2) as a source of carbon in a changing world faced with a fast depletion of natural carbon sources and in need of a low-carbon, resource-efficient economy? One of the points emerging from this discussion concerns the use of CO(2) for the production of olefins (substituting into or integrating with current energy-intensive methodologies that start from oil or syngas from other fossil fuel resources) if H(2) from renewable resources were available at competitive costs. This offers an opportunity to accelerate the introduction of renewable energy into the chemical production chain, and thus to improve resource efficiency in this important manufacturing sector.

  17. Interim storage of spent and disused sealed sources: optimisation of external dose distribution in waste grids using the MCNPX code.

    PubMed

    Paiva, I; Oliveira, C; Trindade, R; Portugal, L

    2005-01-01

    Radioactive sealed sources are in use worldwide in different fields of application. When no further use is foreseen for these sources, they become spent or disused sealed sources and are subject to a specific waste management scheme. Portugal does have a Radioactive Waste Interim Storage Facility where spent or disused sealed sources are conditioned in a cement matrix inside concrete drums and following the geometrical disposition of a grid. The gamma dose values around each grid depend on the drum's enclosed activity and radionuclides considered, as well as on the drums distribution in the various layers of the grid. This work proposes a method based on the Monte Carlo simulation using the MCNPX code to estimate the best drum arrangement through the optimisation of dose distribution in a grid. Measured dose rate values at 1 m distance from the surface of the chosen optimised grid were used to validate the corresponding computational grid model.

  18. On the extraction of the external drain and source resistors and effective channel length in Si-MOSFET

    NASA Astrophysics Data System (ADS)

    Joodaki, M.

    2015-09-01

    This paper focuses on the extraction of drain/source resistance and effective channel length (Leff) of the silicon MOSFET in the linear drain current region. Leff is expressed as a function of drain/source resistance, drain current, threshold voltage, drain voltage, and body-effect coefficient. Using this definition, an additional component of drain/source resistance in the linear drain current region, inversion charge reduction resistance (RΔQ), is introduced which results from the influence of drain/source resistors, internal source/body voltage and drain voltage on the total inversion charge. Finally, a new method for extraction of the drain/source resistance is developed. In this method several parameters that have impact on device behavior are considered. The parameters include gate voltage dependency, short channel effects, and poly gate length dependency. The results presented here are not only very useful for accurate device modeling and characterization, but are also vital to better understanding of the device physics. Furthermore, they can describe shortcomings of the other methods which use devices of different gate lengths. The extracted linear model provides less than 1.07% and 3.3% average absolute error and maximum error, respectively, for all seven devices under test over the gate voltage range of 0.75-2 V.

  19. Geochemistry of dissolved inorganic carbon in a Coastal Plain aquifer. 2. Modeling carbon sources, sinks, and δ13C evolution

    USGS Publications Warehouse

    McMahon, Peter B.; Chapelle, Francis H.

    1991-01-01

    Stable isotope data for dissolved inorganic carbon (DIC), carbonate shell material and cements, and microbial CO2 were combined with organic and inorganic chemical data from aquifer and confining-bed pore waters to construct geochemical reaction models along a flowpath in the Black Creek aquifer of South Carolina. Carbon-isotope fractionation between DIC and precipitating cements was treated as a Rayleigh distillation process. Organic matter oxidation was coupled to microbial fermentation and sulfate reduction. All reaction models reproduced the observed chemical and isotopic compositions of final waters. However, model 1, in which all sources of carbon and electron-acceptors were assumed to be internal to the aquifer, was invalidated owing to the large ratio of fermentation CO2 to respiration CO2 predicted by the model (5–49) compared with measured ratios (two or less). In model 2, this ratio was reduced by assuming that confining beds adjacent to the aquifer act as sources of dissolved organic carbon and sulfate. This assumption was based on measured high concentrations of dissolved organic acids and sulfate in confining-bed pore waters (60–100 μM and 100–380 μM, respectively) relative to aquifer pore waters (from less than 30 μM and 2–80 μM, respectively). Sodium was chosen as the companion ion to organic-acid and sulfate transport from confining beds because it is the predominant cation in confining-bed pore waters. As a result, excessive amounts of Na-for-Ca ion exchange and calcite precipitation (three to four times more cement than observed in the aquifer) were required by model 2 to achieve mass and isotope balance of final water. For this reason, model 2 was invalidated. Agreement between model-predicted and measured amounts of carbonate cement and ratios of fermentation CO2 to respiration CO2 were obtained in a reaction model that assumed confining beds act as sources of DIC, as well as organic acids and sulfate. This assumption was

  20. Geochemistry of dissolved inorganic carbon in a Coastal Plain aquifer. 2. Modeling carbon sources, sinks, and δ13C evolution

    USGS Publications Warehouse

    McMahon, Peter B.; Chapelle, Francis H.

    1991-01-01

    Stable isotope data for dissolved inorganic carbon (DIC), carbonate shell material and cements, and microbial CO2 were combined with organic and inorganic chemical data from aquifer and confining-bed pore waters to construct geochemical reaction models along a flowpath in the Black Creek aquifer of South Carolina. Carbon-isotope fractionation between DIC and precipitating cements was treated as a Rayleigh distillation process. Organic matter oxidation was coupled to microbial fermentation and sulfate reduction. All reaction models reproduced the observed chemical and isotopic compositions of final waters. However, model 1, in which all sources of carbon and electron-acceptors were assumed to be internal to the aquifer, was invalidated owing to the large ratio of fermentation CO2 to respiration CO2 predicted by the model (5–49) compared with measured ratios (two or less). In model 2, this ratio was reduced by assuming that confining beds adjacent to the aquifer act as sources of dissolved organic carbon and sulfate. This assumption was based on measured high concentrations of dissolved organic acids and sulfate in confining-bed pore waters (60–100 μM and 100–380 μM, respectively) relative to aquifer pore waters (from less than 30 μM and 2–80 μM, respectively). Sodium was chosen as the companion ion to organic-acid and sulfate transport from confining beds because it is the predominant cation in confining-bed pore waters. As a result, excessive amounts of Na-for-Ca ion exchange and calcite precipitation (three to four times more cement than observed in the aquifer) were required by model 2 to achieve mass and isotope balance of final water. For this reason, model 2 was invalidated. Agreement between model-predicted and measured amounts of carbonate cement and ratios of fermentation CO2 to respiration CO2 were obtained in a reaction model that assumed confining beds act as sources of DIC, as well as organic acids and sulfate. This assumption was supported

  1. Radiocarbon Analysis Source Apportionment of Fossil and Modern Atmospheric Carbon from DISCOVER-AQ Houston

    NASA Astrophysics Data System (ADS)

    Ortiz, S. M.; Yoon, S.; Barrett, T. E.; Usenko, S.; Sheesley, R. J.

    2015-12-01

    DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Resolved Observations Relevant to Air Quality) is a sampling campaign aimed to monitor regional atmospheric pollutants within a collection of cities across the United States. In September 2013, ground-based air samplers were placed selectively to represent the city of Houston: Moody Tower (downtown; urban) and Manvel Croix (southern; suburb), Conroe (far north; suburb) and La Porte (east; urban industrial), with the goal of understanding particulate matter sources and composition and exposure in urban communities. Radiocarbon analysis was conducted on TSP (total suspended particulate matter) and PM2.5 (particulate matter less than 2.5 μm in aerodynamic diameter) from ground-based samplers. Radiocarbon is used to determine the contributions of contemporary and fossil sources to carbonaceous aerosol in Houston. Contemporary sources of atmospheric carbon in TSP and PM2.5 include primary biogenic emissions, biomass combustion and SOA produced in the atmosphere from biogenic- and biomass combustion-derived volatile organic carbon. Fossil sources of atmospheric carbon in PM2.5 and TSP include all types of primary fossil fuel combustion and SOA produced in the atmosphere from fossil-derived volatile organic carbon. Results from the last week of the campaign, September 21-28th, displayed a PM2.5 contemporary carbon fraction of 48-78% for Moody Tower, 59-86% for Manvel Croix, 66-89% for Conroe. Ambient TSP had contemporary carbon fractions of 51-65% for Moody Tower and 51-83% for La Porte.

  2. Methane-derived authigenic carbonates of mid-Cretaceous age in southern Tibet: Types of carbonate concretions, carbon sources, and formation processes

    NASA Astrophysics Data System (ADS)

    Liang, Huimin; Chen, Xi; Wang, Chengshan; Zhao, Dekun; Weissert, Helmut

    2016-01-01

    Methane-derived authigenic carbonates with distinctive structures and morphologies have been documented worldwide, but they are rarely found from ancient strata in the Eastern Tethys Ocean. The methane-derived authigenic carbonates found in southern Tibet are developed in calcareous or silty shales of mid-Cretaceous age in the Xigaze forearc basin and in the Tethyan Himalaya tectonic zone. The morphology, mineralogy, elemental geochemistry and composition of carbon and oxygen isotopes of these carbonates are studied in detail. The carbonates have nodular, tubular, and tabular morphologies. They are primarily composed of carbonate cement that binds and partly replaces host sediment grains; host siliciclastic sediments are composed mainly of quartz and plagioclase feldspar; a few foraminifers; and framboidal or subhedral to euhedral pyrite. Carbonate cements dominantly are micritic calcite, with minor contribution of dolomite. Nodular concretions are characterized by depleted δ13C values, commonly ranging from -30‰ to -5‰. The δ13C values show a gradual decrease from the periphery to the center, and the CaO, SiO2, Fe2O3, Al2O3, K2O, and TiO2 contents generally show a gradual change. These features indicate that the nodular concretions grew from an early-formed center toward the periphery, and that the carbon source of the nodular concretions was derived from a mixture of methane, methanogenic CO2, and seawater-dissolved inorganic carbon. The tubular concretions are characterized by δ13C values of -8.85‰ to -3.47‰ in the Shangba Section, and -27.37‰ to -23.85‰ in the upper Gamba Section. Unlike the nodular concretions, the tubular concretions show central conduits, which are possible pathways of methane-rich fluids, suggesting that the cementation of tubular concretions begins at the periphery and proceeds inward. Moreover, the tubular concretions show morphological similarity with the methane-derived carbonate chimneys, pipes and slabs reported in

  3. Methods of analysis for complex organic aerosol mixtures from urban emission sources of particulate carbon

    SciTech Connect

    Mazurek, M.A. ); Hildemann, L.M. . Dept. of Civil Engineering); Cass, G.R.; Rogge, W.F. ); Simoneit, B.R.T. . Coll. of Oceanography)

    1990-10-01

    Organic aerosols comprise approximately 30% by mass of the total fine particulate matter present in urban atmospheres. The chemical composition of such aerosols is complex and reflects input from multiple sources of primary emissions to the atmosphere, as well as from secondary production of carbonaceous aerosol species via photochemical reactions. To identify discrete sources of fine carbonaceous particles in urban atmospheres, analytical methods must reconcile both bulk chemical and molecular properties of the total carbonaceous aerosol fraction. This paper presents an overview of the analytical protocol developed and used in a study of the major sources of fine carbon particles emitted to an urban atmosphere. 23 refs., 1 fig., 2 tabs.

  4. Atmospheric carbonyl sulfide sources from anthropogenic activity: Implications for carbon cycle constraints

    SciTech Connect

    Campbell, Elliott; Whelan, Mary; Seibt, U.; Smith, Steven J.; Berry, Joe; Hilton, Timothy W.

    2015-04-28

    Carbonyl sulfide (COS) has recently emerged as an atmospheric tracer of gross primary production. All modeling studies of COS air-monitoring data rely on a climatological anthropogenic inventory that does not reflect present conditions or support interpretation of ice core and firn trends. Here we develop a global anthropogenic inventory for the years 1850 to 2013 based on new emission measurements and material-specific data. By applying methods from a recent regional inventory to global data, we find that the anthropogenic source is similar in magnitude to the plant sink, confounding carbon cycle applications. However, a material-specific approach results in a current anthropogenic source that is only one-third of plant uptake and is concentrated in Asia, supporting carbon cycle applications of global air-monitoring data. Furthermore, the source alone cannot explain the century-scale mixing ratio growth, which suggests that ice and firn data may provide the first global history of gross primary production.

  5. Isotopic evidence of magmatism and a sedimentary carbon source at the Endeavour hydrothermal system

    SciTech Connect

    Brown, T A; Proskurowski, G; Lilley, M D

    2004-01-07

    Stable and radiocarbon isotope measurements made on CO{sub 2} from high temperature hydrothermal vents on the Endeavour Segment of the Juan de Fuca Ridge indicate both magmatic and sedimentary sources of carbon to the hydrothermal system. The Endeavour segment is devoid of overlying sediments and has shown no observable signs of surficial magmatic activity during the {approx}20 years of ongoing studies. The appearance of isotopically heavy, radiocarbon dead CO{sub 2} after a 1999 earthquake swarm requires that this earthquake event was magmatic in origin. Evidence for a sedimentary organic carbon source suggests the presence of buried sediments at the ridge axis. These findings, which represent the first temporally coherent set of radiocarbon measurements from hydrothermal vent fluids, demonstrate the utility of radiocarbon analysis in hydrothermal studies. The existence of a sediment source at Endeavour and the occurrence of magmatic episodes illustrate the extremely complex and evolving nature of the Endeavour hydrothermal system.

  6. Morphogenesis and Production of Enzymes by Penicillium echinulatum in Response to Different Carbon Sources

    PubMed Central

    Schneider, Willian Daniel Hahn; dos Reis, Laísa; Dillon, Aldo José Pinheiro

    2014-01-01

    The effect of different carbon sources on morphology and cellulase and xylanase production of Penicillium echinulatum was evaluated in this work. Among the six carbon sources studied, cellulose and sugar cane bagasse were the most suitable for the production of filter paper activity, endoglucanases, xylanases, and β-glucosidases. However, sucrose and glucose showed β-glucosidase activities similar to those obtained with the insoluble sources. The polyacrylamide gels proved the enzymatic activity, since different standards bands were detected in the media mentioned above. Regarding morphology, it was observed that the mycelium in a dispersed form provided the greatest enzymatic activity, possibly due to greater interaction between the substrate and hyphae. These data are important in understanding the physiology of fungi and could contribute to obtaining enzyme with potential application in the technology of second generation ethanol. PMID:24877074

  7. Biological sulfate reduction using gas-lift reactors fed with hydrogen and carbon dioxide as energy and carbon source

    SciTech Connect

    Houten, R.T. van; Hulshoff Pol, L.W.; Lettinga, G. . Dept. of Environmental Technology)

    1994-08-20

    Feasibility and engineering aspects of biological sulfate reduction in gas-lift reactors were studied. Hydrogen and carbon dioxide were used as energy and carbon source. Attention was paid to biofilm formation, sulfide toxicity, sulfate conversion rate optimization, and gas-liquid mass transfer limitations. Sulfate-reducing bacteria formed stable biofilms on pumice particles. Biofilm formation was not observed when basalt particles were used. However, use of basalt particles led to the formation of granules of sulfate-reducing biomass. The sulfate-reducing bacteria, grown on pumice, easily adapted to free H[sub 2]S concentrations up to 450 mg/L. Biofilm growth rate then equilibrated biomass loss rate. These high free H[sub 2]S concentrations caused reversible inhibition rather than acute toxicity. When free H[sub 2]S concentrations were kept below 450 mg/L, a maximum sulfate conversion rate of 30 g SO[sub 4][sup 2[minus

  8. Radiocarbon source apportionment of urban and wildfire black and organic carbon aerosols

    NASA Astrophysics Data System (ADS)

    Mouteva, G.; Fahrni, S. M.; Santos, G.; Randerson, J. T.; Czimczik, C. I.

    2013-12-01

    Fossil and non-fossil sources of black carbon (BC) and organic carbon (OC) in carbonaceous aerosols can be quantified unambiguously by radiocarbon (14C) measurements. However, accurate 14C-based source apportionment requires a clear and reproducible physical separation of OC and BC, as well as minimal sample contaminations with non-sample carbon. To achieve a clear separation, we used a thermo-optical aerosol analyzer (Sunset Laboratory Inc, USA) with a newly established protocol (Swiss_4S protocol, Zhang et al., 2012), specifically optimized to completely separate the OC and BC fractions with minimal charring and maximum BC recovery. A simple and efficient vacuum line was coupled to the analyzer to trap produced CO2 with high yields and low carbon blanks. Upon trapping, CO2 samples sealed into glass ampoules were converted to graphite and measured for their radiocarbon content at the Keck Carbon Cycle Accelerator Mass Spectrometry Laboratory at the University of California, Irvine. Here, we present the results from the radiocarbon analysis of a set of 14C reference materials, blanks and inter-comparison samples for both OC and BC with sample sizes as small as 5 μg C. We will also present initial results from a set of urban aerosol samples from Salt Lake City, collected throughout 2012 and 2013, and from interior Alaska, collected during the summer of 2013 near the Stuart Creek 2 wildfire.

  9. Application of biogenic carbon dioxide produced by yeast with different carbon sources for attraction of mosquitoes towards adult mosquito traps.

    PubMed

    Sukumaran, D; Ponmariappan, S; Sharma, Atul K; Jha, Hemendra K; Wasu, Yogesh H; Sharma, Ajay K

    2016-04-01

    Surveillance is a prime requisite for controlling arthropod vectors like mosquitoes that transmit diseases such as malaria, dengue and chikungunya. Carbon dioxide (CO2) is one of the main cues from vertebrate breath that attracts mosquitoes towards the host. Hence, CO2 is used as an attractant during surveillance of mosquitoes either from commercial cylinders or dry ice for mosquito traps. In the present study, the biogenic carbon dioxide production was optimized with different carbon sources such as glucose, simple sugar and jaggery with and without yeast peptone dextrose (YPD) media using commercial baker's yeast. The results showed that yeast produced more biogenic CO2 with simple sugar as compared to other carbon sources. Further substrate concentration was optimized for the continuous production of biogenic CO2 for a minimum of 12 h by using 10 g of baker's yeast with 50 g of simple sugar added to 1.5 l distilled water (without YPD media) in a 2-l plastic bottle. This setup was applied in field condition along with two different mosquito traps namely Mosquito Killing System (MKS) and Biogents Sentinel (BGS) trap. Biogenic CO2 from this setup has increased the trapping efficiency of MKS by 6.48-fold for Culex quinquefasciatus, 2.62-fold for Aedes albopictus and 1.5-fold for Anopheles stephensi. In the case of BGS, the efficiency was found to be increased by 3.54-fold for Ae. albopictus, 4.33-fold for An. stephensi and 1.3-fold for Armigeres subalbatus mosquitoes. On the whole, plastic bottle setup releasing biogenic CO2 from sugar and yeast has increased the efficiency of MKS traps by 6.38-fold and 2.74-fold for BGS traps as compared to traps without biogenic CO2. The present study reveals that, among different carbon sources used, simple sugar as a substance (which is economical and readily available across the world) yielded maximum biogenic CO2 with yeast. This setup can be used as an alternative to CO2 cylinder and dry ice in any adult mosquito traps to

  10. A Carbon Source Apportionment Shift in Mexico City Atmospheric Particles During 2003-2004 as Determined with Stable Carbon Isotopes

    NASA Astrophysics Data System (ADS)

    Lopez-Veneroni, D. G.; Vega, E.

    2013-05-01

    The stable carbon isotope composition of atmospheric particles (PM2.5) was measured at La Merced (MER), a commercial site in the eastern sector, and at Xalostoc (XAL) an industrial site in the NE sector of Mexico City, during three sampling periods in autumn 2003, and spring and autumn 2004. At each site and sampling campaign particle samples were collected daily with minivol samplers during two week periods. Ancillary data included organic and elemental carbon, trace elements and ionic species. This data base was complement with air quality data from the RAMA (Automatic Atmospheric Monitoring Network). In general, particle concentrations, ionic species and some air quality species showed higher concentrations in autumn and lowest values in spring. Moreover, the concentrations of these chemical species were highest at XAL compared to MER. The stable carbon isotope composition of PM2.5 during autumn 2003 and spring 2004 had and average value of -26.04 (± 1.54) ‰ vs. PDB. Differences in the isotopic composition between the two sites were non significant. The average δ13C during these seasons were 1 ‰ lighter relative to data collected previously at these sites during 2000 and 2001, and is consistent with a predominant source of hydrocarbon combustion. In autumn 2004, however, average δ13C at XAL and MER increased to -22.8 (± 0.9) and -20.6 (± 3.1) ‰, respectively. Organic carbon concentrations during this period increased concomitantly at these sites. The shift in the isotopic composition in ambient particles suggests a predominance of soil-derived carbon during this period. The possible causes and implications of this are discussed.

  11. Source contributions to black carbon mass fractions in aerosol particles over the northwestern Pacific

    NASA Astrophysics Data System (ADS)

    Koga, Seizi; Maeda, Takahisa; Kaneyasu, Naoki

    Aerosol particle number size distributions above 0.3 μm in diameter and black carbon mass concentrations in aerosols were observed on Chichi-jima of the Ogasawara Islands in the northwestern Pacific from January 2000 to December 2002. Chichi-jima is suitable to observe polluted air masses from East Asia in winter and clean air masses over the western North Pacific in summer. In winter, aerosols over Chichi-jima were strongly affected by anthropogenic emissions in East Asia. The form of energy consumption in East Asia varies in various regions. Hence, each source region is expected to be characterized by an individual black carbon mass fraction. A three-dimensional Eulerian transport model was used to estimate contribution rates to air pollutants from each source region in East Asia. Because the Miyake-jima eruption began at the end of June 2000, the influence of smokes from Miyake-jima was also considered in the model calculation. The results of model calculations represent what must be noticed about smokes from volcanoes including Miyake-jima to interpret temporal variations of sulfur compounds over the northwestern Pacific. To evaluate black carbon mass fractions in anthropogenic aerosols as a function of source region, the relationships between the volume concentration of aerosol particles and the black carbon mass concentration in the winter were classified under each source region in East Asia. Consequently, the black carbon mass fractions in aerosols from China, Japan and the Korean Peninsula, and other regions were estimated to be 9-13%, 5-7%, and 4-5%, respectively.

  12. In silico carbon molecular beam epitaxial growth of graphene on the h-BN substrate: carbon source effect on van der Waals epitaxy.

    PubMed

    Lee, Jonghoon; Varshney, Vikas; Park, Jeongho; Farmer, Barry L; Roy, Ajit K

    2016-05-05

    Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon molecular beam epitaxy (CMBE) techniques using solid carbon sublimation have reported relatively poor quality of the graphene. In this article, the CMBE growth of graphene on the h-BN substrate is numerically studied in order to identify the effect of the carbon source on the quality of the graphene film. The carbon molecular beam generated by the sublimation of solid carbon source materials such as graphite and glassy carbon is mostly composed of atomic carbon, carbon dimers and carbon trimers. Therefore, the graphene film growth becomes a complex process involving various deposition characteristics of a multitude of carbon entities. Based on the study of surface adsorption and film growth characteristics of these three major carbon entities comprising graphite vapour, we report that carbon trimers convey strong traits of vdW epitaxy prone to high quality graphene growth, while atomic carbon deposition is a surface-reaction limited process accompanied by strong chemisorption. The vdW epitaxial behaviour of carbon trimers is found to be substantial enough to nucleate and develop into graphene like planar films within a nanosecond of high flux growth simulation, while reactive atomic carbons tend to impair the structural integrity of the crystalline h-BN substrate upon deposition to form an amorphous interface between the substrate and the growing carbon film. The content of reactive atomic carbons in the molecular beam is suspected to be the primary cause of low quality graphene reported in the literature. A possible optimization of the molecular beam composition towards the synthesis of better quality graphene films is suggested.

  13. Sources of carbon and sulfur nutrition for consumers in three meromictic lakes of New York State

    NASA Technical Reports Server (NTRS)

    Fry, B.; Hayes, J. M. (Principal Investigator)

    1986-01-01

    The trophic importance of bacterioplankton as a source of carbon and sulfur nutrition for consumers in meromictic lakes was tested using stable carbon (delta 13C) and sulfur (delta 34S) isotopic measurements. Studies in three lakes near Syracuse, New York, showed that most consumers ultimately derive their C and S nutrition from a mixture of terrestrial detritus, phytoplankton, and littoral vegetation, rather than from bacterioplankton. Food webs in these meromictic lakes are thus similar to those in other lakes that lack dense populations of bacterioplankton.

  14. Diagnostic air quality model evaluation of source-specific primary and secondary fine particulate carbon.

    PubMed

    Napelenok, Sergey L; Simon, Heather; Bhave, Prakash V; Pye, Havala O T; Pouliot, George A; Sheesley, Rebecca J; Schauer, James J

    2014-01-01

    Ambient measurements of 78 source-specific tracers of primary and secondary carbonaceous fine particulate matter collected at four midwestern United States locations over a full year (March 2004-February 2005) provided an unprecedented opportunity to diagnostically evaluate the results of a numerical air quality model. Previous analyses of these measurements demonstrated excellent mass closure for the variety of contributing sources. In this study, a carbon-apportionment version of the Community Multiscale Air Quality (CMAQ) model was used to track primary organic and elemental carbon emissions from 15 independent sources such as mobile sources and biomass burning in addition to four precursor-specific classes of secondary organic aerosol (SOA) originating from isoprene, terpenes, aromatics, and sesquiterpenes. Conversion of the source-resolved model output into organic tracer concentrations yielded a total of 2416 data pairs for comparison with observations. While emission source contributions to the total model bias varied by season and measurement location, the largest absolute bias of -0.55 μgC/m(3) was attributed to insufficient isoprene SOA in the summertime CMAQ simulation. Biomass combustion was responsible for the second largest summertime model bias (-0.46 μgC/m(3) on average). Several instances of compensating errors were also evident; model underpredictions in some sectors were masked by overpredictions in others.

  15. Stable carbon and nitrogen isotope analysis of TNT: two-dimensional source identification.

    PubMed

    Coffin, R B; Miyares, P H; Kelley, C A; Cifuentes, L A; Reynolds, C M

    2001-12-01

    Data from a combination of laboratory and fieldwork is presented to initiate testing of stable carbon and nitrogen isotope ratios to trace sources of TNT in contaminated soil and groundwater. Evaluation of these extraction methods resulted in 99.9 and 99.8% recovery of TNT with Soxhlet and solid-phase extraction (SPE), respectively. As a result of the high extraction efficiency, isotope fractionation did not occur, thus providing an accurate stable isotope value on TNT from laboratory and field samples. Subsequent experiments evaluated the stability of isotope signatures through incubations lasting up to four weeks with a 70% decline in the TNT concentration. During these experiments, no significant variation in stable carbon and nitrogen isotope ratios was measured. Five different sources of TNT, compared for stable carbon and nitrogen isotope ratios, showed a range of 4.2 and 15%, respectively. This large range in the isotope ratios suggests excellent potential to trace sources in a complex environment. Finally, a site was surveyed for concentrations and isotope values of TNT extracted from groundwaters. Values from this site were substantially different relative to the variation measured on standards and in laboratory incubation experiments. The data set indicates good potential to use stable isotopes to determine TNT sources and fate in the environment.

  16. Tracing Carbon Sources through Aquatic and Terrestrial Food Webs Using Amino Acid Stable Isotope Fingerprinting

    PubMed Central

    Larsen, Thomas; Ventura, Marc; Andersen, Nils; O’Brien, Diane M.; Piatkowski, Uwe; McCarthy, Matthew D.

    2013-01-01

    Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ13C patterns among amino acids (δ13CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ13CAA patterns in contrast to bulk δ13C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ13CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ13C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ13C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs. PMID:24069196

  17. Tracing carbon sources through aquatic and terrestrial food webs using amino acid stable isotope fingerprinting.

    PubMed

    Larsen, Thomas; Ventura, Marc; Andersen, Nils; O'Brien, Diane M; Piatkowski, Uwe; McCarthy, Matthew D

    2013-01-01

    Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ(13)C patterns among amino acids (δ(13)CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ(13)CAA patterns in contrast to bulk δ(13)C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ(13)CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ(13)C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ(13)C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs.

  18. Friction and wear performance of diamondlike carbon films grown in various source gas plasmas

    SciTech Connect

    Erdemir, A.; Nilufer, I. B.; Eryilmaz, O. L.; Beschliesser, M.; Fenske, G. R.

    2000-01-18

    In this study, the authors investigated the effects of various source gases (methane, ethane, ethylene, and acetylene) on the friction and wear performance of diamondlike carbon (DLC) films prepared in a plasma enhanced chemical vapor deposition (PECVD) system. Films were deposited on AISI H13 steel substrates and tested in a pin-on-disk machine against DLC-coated M50 balls in dry nitrogen. They found a close correlation between friction coefficient and source gas composition. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios exhibited lower friction coefficients and higher wear resistance than films grown in source gases with lower hydrogen-to-carbon (H/C) ratios. The lowest friction coefficient (0.014) was achieved with a film derived from methane with an WC ratio of 4, whereas the coefficient of films derived from acetylene (H/C = 1) was of 0.15. Similar correlations were observed for wear rates. Specifically, films derived from gases with lower H/C values were worn out and the substrate material was exposed, whereas films from methane and ethane remained intact and wore at rates that were nearly two orders of magnitude lower than films obtained from acetylene.

  19. Feasibility study of using brine for carbon dioxide capture and storage from fixed sources

    SciTech Connect

    Daniel Dziedzic; Kenneth B. Gross; Robert A. Gorski; John T. Johnson

    2006-12-15

    A laboratory-scale reactor was developed to evaluate the capture of carbon dioxide (CO{sub 2}) from a gas into a liquid as an approach to control greenhouse gases emitted from fixed sources. CO{sub 2} at 5-50% concentrations was passed through a gas-exchange membrane and transferred into liquid media - tap water or simulated brine. When using water, capture efficiencies exceeded 50% and could be enhanced by adding base (e.g., sodium hydroxide) or the combination of base and carbonic anhydrase, a catalyst that speeds the conversion of CO{sub 2} to carbonic acid. The transferred CO{sub 2} formed ions, such as bicarbonate or carbonate, depending on the amount of base present. Adding precipitating cations, like Ca{sup ++}, produced insoluble carbonate salts. Simulated brine proved nearly as efficient as water in absorbing CO{sub 2}, with less than a 6% reduction in CO{sub 2} transferred. The CO{sub 2} either dissolved into the brine or formed a mixture of gas and ions. If the chemistry was favorable, carbonate precipitate spontaneously formed. Energy expenditure of pumping brine up and down from subterranean depths was modeled. We concluded that using brine in a gas-exchange membrane system for capturing CO{sub 2} from a gas stream to liquid is technically feasible and can be accomplished at a reasonable expenditure of energy. 24 refs., 9 figs., 2 tabs., 1 app.

  20. Stable carbon isotope analysis in a South Texas cave: Investigating sources of CO2 production

    NASA Astrophysics Data System (ADS)

    Thompson, Reece

    Studies of interactions between modern local climate, cave atmosphere, and ?13C ratios are needed to determine sources of CO2 in caves, and the cycles of seasonal variations that alter karst geochemistry. A seasonal study, focusing on the analysis of stable isotopes collected from a modern cave system, was conducted in Robber Baron Cave (RBC) in order to identify sources of CO2 in its atmosphere. Determining what conditions affect cave morphology and the transfer path of carbon through a cave system is necessary in order to assess the role of caves in the carbon cycle and correctly interpret past ecological changes. This study investigates the extent that stable isotopic values of carbon in CO2 are affected by CO2 sourced from soils, bedrock, atmospheric air, and vegetation, and how ?13C signals are transmitted in a modern cave system. This study also measures how ventilation affects CO2 concentration and ?13C on seasonal scales. In-cave air grab samples were collected monthly at various transects located in RBC in order to measure CO2 composition in addition to factors such as temperature, and barometric pressure. Soil gas and limestone bedrock were also collected and tested for ?13C composition. Air samples were analyzed using an Ambient Air-Model G2101-I Picarro Cavity Ring-Down Spectroscopy Analyzer for both the concentration and ?13C isotopic value of CO2. These values were then compared to isotopic values of known sources of CO2 in order to determine possible sources of CO2 that result in high CO2 concentrations found in RBC. The background stable isotopic value of carbon from CO2 measured in RBC is -19.1‰ VPDB.

  1. Characterization of Arctic elemental carbon in Barrow, AK using radiocarbon source apportionment

    NASA Astrophysics Data System (ADS)

    Barrett, T. E.; Usenko, S.; Robinson, E. M.; Sheesley, R. J.

    2013-12-01

    Currently, the Arctic is one of the fastest warming regions on earth with surface temperatures increasing at a rate nearly double the global mean over recent decades. Despite the fact that atmospheric concentrations of elemental carbon (EC) are lower in the Arctic than in lower latitudes, deposition of EC on snow and ice may exacerbate regional warming by simultaneously decreasing albedo and increasing melt rates. Due to the intensifying Arctic oil exploration in areas such as the Beaufort and Chukchi seas, the impact of new emission sources such as heavy fuel and heavy diesel combustion on regional carbon needs to be assessed. The first step in developing mitigation strategies for reducing current and future EC emissions in the Arctic is to determine emission source contributions. This study aims to determine the relative contributions of fossil fuel and biomass combustion and to identify major source regions of EC to the Arctic. Radiocarbon analysis of both total organic carbon (TOC) and EC combined with organic tracer and back trajectory analysis has been applied to a set of wintertime coarse particulate matter (PM10) samples from Barrow, AK. Preliminary apportionment for January 2013 indicates roughly half of TOC is from biogenic/biomass burning emissions and one third of EC is due to biomass burning emissions. The radiocarbon results will be combined with organic tracer analysis (polycyclic aromatic hydrocarbons, petroleum biomarkers and normal alkanes), increasing the specificity of the relative contribution of both the fossil and modern (biogenic/biomass burning) carbon emission sources. This research represents the first reported radiocarbon values for Arctic EC, providing highly conclusive source apportionment prior to the influence of increased drilling operations and ship traffic in the Beaufort and Chukchi seas.

  2. Adherent diamond like carbon coatings on metals via plasma source ion implantation

    SciTech Connect

    Walter, K.C.; Nastasi, M.; Munson, C.P.

    1996-12-01

    Various techniques are currently used to produce diamond-like carbon (DLC) coatings on various materials. Many of these techniques use metallic interlayers, such as Ti or Si, to improve the adhesion of a DLC coating to a ferrous substrate. An alternative processing route would be to use plasma source ion implantation (PSII) to create a carbon composition gradient in the surface of the ferrous material to serve as the interface for a DLC coating. The need for interlayer deposition is eliminated by using a such a graded interfaces PSII approach has been used to form adherent DLC coatings on magnesium, aluminum, silicon, titanium, chromium, brass, nickel, and tungsten. A PSII process tailored to create a graded interface allows deposition of adherent DLC coatings even on metals that exhibit a positive heat of formation with carbon, such as magnesium, iron, brass and nickel.

  3. Multiple Phosphatases Regulate Carbon Source-Dependent Germination and Primary Metabolism in Aspergillus nidulans.

    PubMed

    de Assis, Leandro José; Ries, Laure Nicolas Annick; Savoldi, Marcela; Dinamarco, Taisa Magnani; Goldman, Gustavo Henrique; Brown, Neil Andrew

    2015-03-11

    Aspergillus nidulans is an important mold and a model system for the study of fungal cell biology. In addition, invasive A. nidulans pulmonary infections are common in humans with chronic granulomatous disease. The morphological and biochemical transition from dormant conidia into active, growing, filamentous hyphae requires the coordination of numerous biosynthetic, developmental, and metabolic processes. The present study exhibited the diversity of roles performed by seven phosphatases in regulating cell cycle, development, and metabolism in response to glucose and alternative carbon sources. The identified phosphatases highlighted the importance of several signaling pathways regulating filamentous growth, the action of the pyruvate dehydrogenase complex as a metabolic switch controlling carbon usage, and the identification of the key function performed by the α-ketoglutarate dehydrogenase during germination. These novel insights into the fundamental roles of numerous phosphatases in germination and carbon sensing have provided new avenues of research into the identification of inhibitors of fungal germination, with implications for the food, feed, and pharmaceutical industries.

  4. Novel attributes and design considerations of source and drain regions in carbon nanotube transistors

    NASA Astrophysics Data System (ADS)

    Orouji, Ali A.; Ahmadmiri, S. A.

    2010-03-01

    Source and drain regions are inseparable sections of carbon nanotube field effect transistor (CNTFET) whose parameters are effective for CNTFET performance. For the first time in this paper, design considerations of source and drain regions are presented by developing a two-dimensional (2-D) full quantum simulation. The simulations have been done by the self-consistent solution of 2-D Poisson-Schrödinger equations, within the nonequilibrium Green’s function (NEGF) formalism. The effects of varying the source and drain parameters are investigated in terms of on-off current ratio, transconductance characteristics, drain conductance, and subthreshold swing. Simulation results demonstrate that we could improve the CNTFET performance with proper selection of the source and drain parameters.

  5. Sources and turnover of organic carbon and methane in fjord and shelf sediments off northern Norway

    NASA Astrophysics Data System (ADS)

    Sauer, Simone; Hong, Wei-Li; Knies, Jochen; Lepland, Aivo; Forwick, Matthias; Klug, Martin; Eichinger, Florian; Baranwal, Soma; Crémière, Antoine; Chand, Shyam; Schubert, Carsten J.

    2016-10-01

    To better understand the present and past carbon cycling and transformation processes in methane-influenced fjord and shelf areas of northern Norway, we compared two sediment cores from the Hola trough and from Ullsfjorden. We investigated (1) the organic matter composition and sedimentological characteristics to study the sources of organic carbon (Corg) and the factors influencing Corg burial, (2) pore water geochemistry to determine the contribution of organoclastic sulfate reduction and methanogenesis to total organic carbon turnover, and (3) the carbon isotopic signature of hydrocarbons to identify the carbon transformation processes and gas sources. High sedimentation and Corg accumulation rates in Ullsfjorden support the notion that fjords are important Corg sinks. The depth of the sulfate-methane-transition (SMT) in the fjord is controlled by the supply of predominantly marine organic matter to the sediment. Organoclastic sulfate reduction accounts for 60% of the total depth-integrated sulfate reduction in the fjord. In spite of the presence of ethane, propane, and butane, we suggest a purely microbial origin of light hydrocarbons in the sediments based on their low δ13C values. In the Hola trough, sedimentation and Corg accumulation rates changed during the deglacial-to-post-glacial transition from approximately 80 cm ka-1 to erosion at present. Thus, Corg burial in this part of the shelf is presently absent. Low organic matter content in the sediment and low rates of organoclastic sulfate reduction (only 3% of total depth-integrated sulfate reduction) entail that the shallow depth of the SMT is controlled mostly by ascending thermogenic methane from deeper sources.

  6. Intrashelf basins: A geologic model for source-bed and reservoir facies deposition within carbonate shelves

    SciTech Connect

    Grover, G. Jr. )

    1993-09-01

    Intrashelf basins (moats, inshore basins, shelf basins, differentiated shelf, and deep-water lagoons of others) are depressions of varying sizes and shapes that occur within tectonically passive and regionally extensive carbonate shelves. Intrashelf basins grade laterally and downdip (seaward) into shallow-water carbonates of the regional shelf, are separated from the open marine basin by the shelf margin, and are largely filled by fine-grained subtidal sediments having attributes of shallow- and deeper water sedimentation. These basins are commonly fringed or overlain by carbonate sands, reefs, or buildups. These facies may mimic those that occur along the regional shelf margin, and they can have trends that are at a high angle to that of the regional shelf. Intrashelf basins are not intracratonic basins. The history of most intrashelf basins is a few million to a few tens of million of years. Examples of intrashelf basins are known throughout the Phanerozoic; the southern portion of the Holocene Belize shelf is a modern example of an intrashelf basin. Two types of intrashelf basins are recognized. Coastal basins pass updip into coastal clastics of the craton with the basin primarily filled by fine clastics. Shelf basins occur on the outer part of the shelf, are surrounded by shallow-water carbonate facies, and are filled by peloidal lime mud, pelagics, and argillaceous carbonates. Intrashelf basins are commonly the site of organic-rich, source-bed deposition, resulting in the close proximity of source beds and reservoir facies that may fringe or overlie the basin. Examples of hydrocarbon-charged reservoirs that were sourced by an intrashelf basin include the Miocene Bombay High field, offshore India; the giant Jurassic (Arab-D) and Cretaceous (Shuaiba) reservoirs of the Arabian Shelf; the Lower Cretaceous Sunniland trend, South Florida basin; and the Permian-Pennsylvanian reservoirs surrounding the Tatum basin in southeastern New Mexico.

  7. Microbial community structure and function of nitrobenzene reduction biocathode in response to carbon source switchover.

    PubMed

    Liang, Bin; Cheng, Haoyi; Van Nostrand, Joy D; Ma, Jincai; Yu, Hao; Kong, Deyong; Liu, Wenzong; Ren, Nanqi; Wu, Liyou; Wang, Aijie; Lee, Duu-Jong; Zhou, Jizhong

    2014-05-01

    The stress of poised cathode potential condition and carbon source switchover for functional biocathode microbial community influences is poorly understood. Using high-throughput functional gene array (GeoChip v4.2) and Illumina 16S rRNA gene MiSeq sequencing, we investigated the phylogenetic and functional microbial community of the initial inoculum and biocathode for bioelectrochemical reduction of nitrobenzene to less toxic aniline in response to carbon source switchover (from organic glucose to inorganic bicarbonate). Selective transformation of nitrobenzene to aniline maintained in the bicarbonate fed biocathode although nitrobenzene reduction rate and aniline formation rate were significantly decreased compared to those of the glucose-fed biocathode. When the electrical circuit of the glucose-fed biocathode was disconnected, both rates of nitrobenzene reduction and of aniline formation were markedly decreased, confirming the essential role of an applied electric field for the enhancement of nitrobenzene reduction. The stress of poised cathode potential condition led to clear succession of microbial communities from the initial inoculum to biocathode and the carbon source switchover obviously changed the microbial community structure of biocathode. Most of the dominant genera were capable of reducing nitroaromatics to the corresponding aromatic amines regardless of the performance mode. Heterotrophic Enterococcus was dominant in the glucose-fed biocathode while autotrophic Paracoccus and Variovorax were dominant in the bicarbonate-fed biocathode. Relatively higher intensity of diverse multi-heme cytochrome c (putatively involved in electrons transfer) and carbon fixation genes was observed in the biocarbonate-fed biocathode, likely met the requirement of the energy conservation and maintained the nitrobenzene selective reduction capability after carbon source switchover. Extracellular pilin, which are important for biofilm formation and potential conductivity

  8. Effusive molecular beam-sampled Knudsen flow reactor coupled to vacuum ultraviolet single photon ionization mass spectrometry using an external free radical source

    SciTech Connect

    Leplat, N.; Rossi, M. J.

    2013-11-15

    A new apparatus using vacuum ultraviolet single photon ionization mass spectrometry (VUV SPIMS) of an effusive molecular beam emanating from a Knudsen flow reactor is described. It was designed to study free radical-molecule kinetics over a significant temperature range (300–630 K). Its salient features are: (1) external free radical source, (2) counterpropagating molecular beam and diffuse VUV photon beam meeting in a crossed-beam ion source of a quadrupole mass spectrometer with perpendicular ion extraction, (3) analog detection of the photocurrent of the free radical molecular cation, and (4) possibility of detecting both free radicals and closed shell species in the same apparatus and under identical reaction conditions owing to the presence of photoelectrons generated by the photoelectric effect of the used VUV-photons. The measured thermal molecular beam-to-background ratio was 6.35 ± 0.39 for Ar and 10.86 ± 1.59 for i-C{sub 4}H{sub 10} at 300 K, a factor of 2.52 and 1.50 smaller, respectively, than predicted from basic gas-dynamic considerations. Operating parameters as well as the performance of key elements of the instrument are presented and discussed. Coupled to an external free radical source a steady-state specific exit flow of 1.6 × 10{sup 11} and 5.0 × 10{sup 11} molecule s{sup −1} cm{sup −3} of C{sub 2}H{sub 5}{sup •} (ethyl) and t-C{sub 4}H{sub 9}{sup •} (t-butyl) free radicals have been detected using VUV SPIMS at their molecular ion m/z 29 and 57, respectively, at 300 K.

  9. Microarray analysis of Neosartorya fischeri using different carbon sources, petroleum asphaltenes and glucose-peptone

    PubMed Central

    Hernández-López, Edna L.; Ramírez-Puebla, Shamayim T.; Vazquez-Duhalt, Rafael

    2015-01-01

    Asphaltenes are considered as the most recalcitrant petroleum fraction and represent a big problem for the recovery, separation and processing of heavy oils and bitumens. Neosartorya fischeri is a saprophytic fungus that is able to grow using asphaltenes as the sole carbon source [1]. We performed transcription profiling using a custom designed microarray with the complete genome from N. fischeri NRRL 181 in order to identify genes related to the transformation of asphaltenes [1]. Data analysis was performed using the genArise software. Results showed that 287 genes were up-regulated and 118 were down-regulated. Here we describe experimental procedures and methods about our dataset (NCBI GEO accession number GSE68146) and describe the data analysis to identify different expression levels in N. fischeri using this recalcitrant carbon source. PMID:26484261

  10. Microarray analysis of Neosartorya fischeri using different carbon sources, petroleum asphaltenes and glucose-peptone.

    PubMed

    Hernández-López, Edna L; Ramírez-Puebla, Shamayim T; Vazquez-Duhalt, Rafael

    2015-09-01

    Asphaltenes are considered as the most recalcitrant petroleum fraction and represent a big problem for the recovery, separation and processing of heavy oils and bitumens. Neosartorya fischeri is a saprophytic fungus that is able to grow using asphaltenes as the sole carbon source [1]. We performed transcription profiling using a custom designed microarray with the complete genome from N. fischeri NRRL 181 in order to identify genes related to the transformation of asphaltenes [1]. Data analysis was performed using the genArise software. Results showed that 287 genes were up-regulated and 118 were down-regulated. Here we describe experimental procedures and methods about our dataset (NCBI GEO accession number GSE68146) and describe the data analysis to identify different expression levels in N. fischeri using this recalcitrant carbon source.

  11. A Review on Alternative Carbon Sources for Biological Treatment of Nitrate Waste

    NASA Astrophysics Data System (ADS)

    Dhamole, Pradip B.; D'Souza, S. F.; Lele, S. S.

    2015-04-01

    Huge amount of wastewater containing nitrogen is produced by various chemical and biological industries. Nitrogen is present in the form of ammonia, nitrate and nitrite. This review deals with treatment of nitrate based effluent using biological denitrification. Because of its adverse effect on aquatic life and human health, treatment of nitrate bearing effluents has become mandatory before discharge. Treatment of such wastes is a liability for the industries and incurs cost. However, the economics of the process can be controlled by selection of proper method and reduction in the operating cost. This paper reviews the advantages and disadvantages of different methods of nitrate removal with emphasis on biological denitrification. The cost of biological denitrification is controlled by the carbon source. Hence, use of alternative carbon sources such as agricultural wastes, industrial effluent or by products is reviewed in this paper. Policies for reducing the cost of nitrate treatment and enhancing the efficiency have been recommended.

  12. Sorbitol as the Primary Carbon Source for the Growth of Embryogenic Callus of Maize.

    PubMed Central

    Swedlund, B.; Locy, R. D.

    1993-01-01

    The effects of various carbon sources on initiation and maintenance of embryogenic callus of maize (Zea mays L.) and on the regeneration of plants from embryogenic callus were studied. Growth of embryogenic callus tissue on media containing sucrose was typified by the subsequent growth of both embryogenic (regenerable) and nonembryogenic (nonregenerable) callus. Growth of embryogenic callus on sorbitol was unique among the carbon sources tested in that sorbitol supported the subsequent growth of only embryogenic callus. Further experiments demonstrated that embryogenic callus grown on sorbitol had a greater regenerative capacity (more plants produced per gram fresh weight of callus) than callus grown on sucrose. Sorbitol dehydrogenase was detected in embryogenic callus of maize at a specific activity roughly equivalent to that found in zygotic embryos of developing seeds. Nonembryogenic callus did not contain significant levels of sorbitol dehydrogenase activity. PMID:12232027

  13. Effect of carbon source on pyrimidine biosynthesis in Pseudomonas alcaligenes ATCC 14909.

    PubMed

    Santiago, Manuel F; West, Thomas P

    2003-01-01

    The effect of carbon source on the regulation of the de novo pyrimidine biosynthetic enzymes in Pseudomonas alcaligenes ATCC 14909 was investigated. The de novo pyrimidine biosynthetic enzymes were measured in extracts of P. alcaligenes ATCC 14909 cells and of cells from an auxotroph deficient for orotate phosphoribosyltransferase activity. Pyrimidine biosynthetic enzyme activities in ATCC 14909 were influenced by pyrimidine supplementation to the culture medium but not by the carbon source present. Pyrimidine limitation of the auxotroph elevated the de novo enzyme activities indicating that this pathway may be controlled at the transcriptional level by a pyrimidine-related compound. Its regulation seemed to be subject to less transcriptional control by a pyrimidine-related compound than what was observed in the closely related species Pseudomonas pseudoalcaligenes.

  14. Polyhydroxyalkanoic acids from structurally-unrelated carbon sources in Escherichia coli.

    PubMed

    Wang, Qian; Zhuang, Qianqian; Liang, Quanfeng; Qi, Qingsheng

    2013-04-01

    Polyhydroxyalkanoates (PHAs) that contain varied monomers with different chain lengths/structures were normally synthesized when a structurally-related precursor was present. The biosynthesis of PHAs from unrelated carbon sources in microorganisms including Escherichia coli met many challenges in the past. Recently, with the development of metabolic engineering and synthetic biology, the production of PHAs from unrelated carbon sources obtained a breakthrough. Polyesters containing 2-hydroxypropionate, 3-hydroxypropionate, 4-hydroxybutyrate, 3-hydroxyvalarate, and medium-chain-length 3-hydroxyalkanoate monomers can all be synthesized in E. coli by integrating exogenous or endogenous pathways and/or genes. This review will summarize the progresses in this area. In addition, the strategies that lead to the production of PHAs with varied monomers and high polymer content in the cell are discussed.

  15. Design of an intense muon source with a carbon and mercury target

    SciTech Connect

    Stratakis, D.; Berg, J. S.; Neuffer, D.; Ding, X.

    2015-05-03

    In high-intensity sources, muons are produced by firing high energy protons onto a target to produce pions. The pions decay to muons which are captured and accelerated. In the present study, we examine the performance of the channel for two different target scenarios: one based on liquid mercury and another one based on a solid carbon target. We produce distributions with the two different target materials and discuss differences in particle spectrum near the sources. We then propagate the distributions through our capture system and compare the full system performance for the two target types.

  16. Design of an Intense Muon Source with a Carbon and Mercury Target

    SciTech Connect

    Stratakis, Diktys; Berg, J. Scott; Neuffer, David; Ding, Xiaoping

    2015-06-01

    In high-intensity sources, muons are produced by firing high energy protons onto a target to produce pions. The pions decay to muons which are captured and accelerated. In the present study, we examine the performance of the channel for two different target scenarios: one based on liquid mercury and another one based on a solid carbon target. We produce distributions with the two different target materials and discuss differences in particle spectrum near the sources. We then propagate the distributions through our capture system and compare the full system performance for the two target types.

  17. Black carbon emissions from Russian diesel sources: case study of Murmansk

    NASA Astrophysics Data System (ADS)

    Evans, M.; Kholod, N.; Malyshev, V.; Tretyakova, S.; Gusev, E.; Yu, S.; Barinov, A.

    2015-02-01

    Black carbon (BC) is a potent pollutant because of its effects on climate change, ecosystems and human health. Black carbon has a particularly pronounced impact as a climate forcer in the Arctic because of its effect on snow albedo and cloud formation. We have estimated BC emissions from diesel sources in Murmansk Region and Murmansk City, the largest city in the world above the Arctic Circle. In this study we developed a detailed inventory of diesel sources including on-road vehicles, off-road transport (mining, locomotives, construction and agriculture), fishing and diesel generators. For on-road transport, we conducted several surveys to understand the vehicle fleet and driving patterns, and, for all sources, we also relied on publicly available local data sets and analysis. We calculated that BC emission in Murmansk Region were 0.40 Gg in 2012. The mining industry is the largest source of BC emissions in the region, emitting 70% of all BC emissions because of its large diesel consumption and absence of emissions controls. On-road vehicles are the second largest source emitting about 12% of emissions. Old heavy duty trucks are the major source of emissions. Emission controls on new vehicles limit total emissions from on-road transportation. Vehicle traffic and fleet surveys show that many of the older cars on the registry are lightly or never used. We also estimated that total BC emissions from diesel sources in Russia were 56.7 Gg in 2010, and on-road transport contributed 55% of diesel BC emissions. Agricultural machinery is also a significant source Russia-wide, in part because of the lack of controls on off-road vehicles.

  18. Black carbon emissions from Russian diesel sources: case study of Murmansk

    NASA Astrophysics Data System (ADS)

    Evans, M.; Kholod, N.; Malyshev, V.; Tretyakova, S.; Gusev, E.; Yu, S.; Barinov, A.

    2015-07-01

    Black carbon (BC) is a potent pollutant because of its effects on climate change, ecosystems and human health. Black carbon has a particularly pronounced impact as a climate forcer in the Arctic because of its effect on snow albedo and cloud formation. We have estimated BC emissions from diesel sources in the Murmansk Region and Murmansk City, the largest city in the world above the Arctic Circle. In this study we developed a detailed inventory of diesel sources including on-road vehicles, off-road transport (mining, locomotives, construction and agriculture), ships and diesel generators. For on-road transport, we conducted several surveys to understand the vehicle fleet and driving patterns, and, for all sources, we also relied on publicly available local data sets and analysis. We calculated that BC emissions in the Murmansk Region were 0.40 Gg in 2012. The mining industry is the largest source of BC emissions in the region, emitting 69 % of all BC emissions because of its large diesel consumption and absence of emissions controls. On-road vehicles are the second largest source, emitting about 13 % of emissions. Old heavy duty trucks are the major source of emissions. Emission controls on new vehicles limit total emissions from on-road transportation. Vehicle traffic and fleet surveys show that many of the older cars on the registry are lightly or never used. We also estimated that total BC emissions from diesel sources in Russia were 50.8 Gg in 2010, and on-road transport contributed 49 % of diesel BC emissions. Agricultural machinery is also a significant source Russia-wide, in part because of the lack of controls on off-road vehicles.

  19. Black carbon emissions from Russian diesel sources. Case study of Murmansk

    DOE PAGES

    Evans, M.; Kholod, N.; Malyshev, V.; ...

    2015-07-27

    Black carbon (BC) is a potent pollutant because of its effects on climate change, ecosystems and human health. Black carbon has a particularly pronounced impact as a climate forcer in the Arctic because of its effect on snow albedo and cloud formation. We have estimated BC emissions from diesel sources in the Murmansk Region and Murmansk City, the largest city in the world above the Arctic Circle. In this study we developed a detailed inventory of diesel sources including on-road vehicles, off-road transport (mining, locomotives, construction and agriculture), ships and diesel generators. For on-road transport, we conducted several surveys tomore » understand the vehicle fleet and driving patterns, and, for all sources, we also relied on publicly available local data sets and analysis. We calculated that BC emissions in the Murmansk Region were 0.40 Gg in 2012. The mining industry is the largest source of BC emissions in the region, emitting 69 % of all BC emissions because of its large diesel consumption and absence of emissions controls. On-road vehicles are the second largest source, emitting about 13 % of emissions. Old heavy duty trucks are the major source of emissions. Emission controls on new vehicles limit total emissions from on-road transportation. Vehicle traffic and fleet surveys show that many of the older cars on the registry are lightly or never used. We also estimated that total BC emissions from diesel sources in Russia were 50.8 Gg in 2010, and on-road transport contributed 49 % of diesel BC emissions. Agricultural machinery is also a significant source Russia-wide, in part because of the lack of controls on off-road vehicles.« less

  20. Black carbon emissions from Russian diesel sources. Case study of Murmansk

    SciTech Connect

    Evans, M.; Kholod, N.; Malyshev, V.; Tretyakova, S.; Gusev, E.; Yu, S.; Barinov, A.

    2015-07-27

    Black carbon (BC) is a potent pollutant because of its effects on climate change, ecosystems and human health. Black carbon has a particularly pronounced impact as a climate forcer in the Arctic because of its effect on snow albedo and cloud formation. We have estimated BC emissions from diesel sources in the Murmansk Region and Murmansk City, the largest city in the world above the Arctic Circle. In this study we developed a detailed inventory of diesel sources including on-road vehicles, off-road transport (mining, locomotives, construction and agriculture), ships and diesel generators. For on-road transport, we conducted several surveys to understand the vehicle fleet and driving patterns, and, for all sources, we also relied on publicly available local data sets and analysis. We calculated that BC emissions in the Murmansk Region were 0.40 Gg in 2012. The mining industry is the largest source of BC emissions in the region, emitting 69 % of all BC emissions because of its large diesel consumption and absence of emissions controls. On-road vehicles are the second largest source, emitting about 13 % of emissions. Old heavy duty trucks are the major source of emissions. Emission controls on new vehicles limit total emissions from on-road transportation. Vehicle traffic and fleet surveys show that many of the older cars on the registry are lightly or never used. We also estimated that total BC emissions from diesel sources in Russia were 50.8 Gg in 2010, and on-road transport contributed 49 % of diesel BC emissions. Agricultural machinery is also a significant source Russia-wide, in part because of the lack of controls on off-road vehicles.

  1. Distinct carbon sources indicate strong differentiation between tropical forest and farmland bird communities.

    PubMed

    Ferger, Stefan W; Böhning-Gaese, Katrin; Wilcke, Wolfgang; Oelmann, Yvonne; Schleuning, Matthias

    2013-02-01

    The conversion of forest into farmland has resulted in mosaic landscapes in many parts of the tropics. From a conservation perspective, it is important to know whether tropical farmlands can buffer species loss caused by deforestation and how different functional groups of birds respond to land-use intensification. To test the degree of differentiation between farmland and forest bird communities across feeding guilds, we analyzed stable C and N isotopes in blood and claws of 101 bird species comprising four feeding guilds along a tropical forest-farmland gradient in Kenya. We additionally assessed the importance of farmland insectivores for pest control in C(4) crops by using allometric relationships, C stable isotope ratios and estimates of bird species abundance. Species composition differed strongly between forest and farmland bird communities. Across seasons, forest birds primarily relied on C(3) carbon sources, whereas many farmland birds also assimilated C(4) carbon. While C sources of frugivores and omnivores did not differ between forest and farmland communities, insectivores used more C(4) carbon in the farmland than in the forest. Granivores assimilated more C(4) carbon than all other guilds in the farmland. We estimated that insectivorous farmland birds consumed at least 1,000 kg pest invertebrates km(-2) year(-1). We conclude that tropical forest and farmland understory bird communities are strongly separated and that tropical farmlands cannot compensate forest loss for insectivorous forest understory birds. In tropical farmlands, insectivorous bird species provide a quantitatively important contribution to pest control.

  2. Silicate or Carbonate Weathering: Fingerprinting Sources of Dissolved Inorganic Carbon Using δ13C in a Tropical River, Southern India

    NASA Astrophysics Data System (ADS)

    Bhagat, H.; Ghosh, P.

    2015-12-01

    Rivers are an inherently vital resource for the development of any region and their importance is highlighted by the presence of many ancient human civilizations adjacent to river systems. δ13C - Si/HCO3 systematics has been applied to large south Indian rivers which drain the Deccan basaltic traps in order to quantify their relative contributions from silicate and carbonate weathering. This study investigates δ13C - Si/HCO3 systematics of the Cauvery River basin which flows through silicate lithology in the higher reaches and carbonate lithology with pedogenic and marine carbonates dominating the terrain in the lower reaches of the basin. The samples for the present study were collected at locations within the watershed during Pre-Monsoon and Monsoon Season 2014. The measurements of stable isotope ratios of δ13CDIC and were accomplished through a Thermo Scientific GasBench II interface connected to a MAT 253 IRMS. We captured a large spatial variation in δ13C and Si/HCO3 values during both seasons; Pre-Monsoon δ13C values ranges between -17.57‰ to -4.02‰ and during Monsoon it varies between -9.19‰ to +0.61‰. These results indicate a two end-member mixing component i.e. a silicate and a carbonate end member; governing the weathering interactions of the Cauvery River. Within the drainage basin, we identified silicate and carbonate dominating sources by using contributions of DIC and δ13C. Si/HCO3 values for Pre-Monsoon ranges between 0.028 - 0.67 and for Monsoon it varies between 0.073 - 0.80. Lighter δ13C composition was observed at sampling sites at higher altitude in contrast to sampling sites at flood plain which show relatively enriched δ13C which indicate mixing of soil derived CO2 with C4 plants. Result suggests dominance of carbonate weathering during the Monsoon Period, while silicate weathering is pronounced during Pre- Monsoon period.

  3. Antimony-assisted carbonization of Si(111) with solid source molecular beam epitaxy

    SciTech Connect

    Hackley, Justin; Richardson, Christopher J. K.; Sarney, Wendy L.

    2013-11-15

    The carbonization of an antimony-terminated Si (111) surface in a solid source molecular beam epitaxy system is presented. Reflection high-energy electron diffraction, atomic force microscopy, x-ray photoelectron spectroscopy, and cross-sectional transmission electron microscopy are used to characterize samples grown with and without antimony termination. It is shown that the antimony-terminated surface promotes the formation of thin, smooth and continuous SiC films at a relatively low temperature of 800 °C.

  4. Dynamic radiography using a carbon-nanotube-based field-emission x-ray source

    SciTech Connect

    Cheng, Y.; Zhang, J.; Lee, Y.Z.; Gao, B.; Dike, S.; Lin, W.; Lu, J.P.; Zhou, O.

    2004-10-01

    We report a dynamic radiography system with a carbon nanotube based field-emission microfocus x-ray source. The system can readily generate x-ray radiation with continuous variation of temporal resolution as short as nanoseconds. Its potential applications for dynamic x-ray imaging are demonstrated. The performance characteristics of this compact and versatile system are promising for noninvasive imaging in biomedical research and industrial inspection.

  5. Stream restoration and sewers impact sources and fluxes of water, carbon, and nutrients in urban watersheds

    NASA Astrophysics Data System (ADS)

    Pennino, Michael J.; Kaushal, Sujay S.; Mayer, Paul M.; Utz, Ryan M.; Cooper, Curtis A.

    2016-08-01

    An improved understanding of sources and timing of water, carbon, and nutrient fluxes associated with urban infrastructure and stream restoration is critical for guiding effective watershed management globally. We investigated how sources, fluxes, and flowpaths of water, carbon (C), nitrogen (N), and phosphorus (P) shift in response to differences in urban stream restoration and sewer infrastructure. We compared an urban restored stream with two urban degraded streams draining varying levels of urban development and one stream with upland stormwater management systems over a 3-year period. We found that there was significantly decreased peak discharge in response to precipitation events following stream restoration. Similarly, we found that the restored stream showed significantly lower (p < 0.05) monthly peak runoff (9.4 ± 1.0 mm day-1) compared with two urban degraded streams (ranging from 44.9 ± 4.5 to 55.4 ± 5.8 mm day-1) draining higher impervious surface cover, and the stream-draining stormwater management systems and less impervious surface cover in its watershed (13.2 ± 1.9 mm day-1). The restored stream exported most carbon, nitrogen, and phosphorus at relatively lower streamflow than the two more urban catchments, which exported most carbon and nutrients at higher streamflow. Annual exports of total carbon (6.6 ± 0.5 kg ha-1 yr-1), total nitrogen (4.5 ± 0.3 kg ha-1 yr-1), and total phosphorus (161 ± 15 kg ha-1 yr-1) were significantly lower in the restored stream compared to both urban degraded streams (p < 0.05), but statistically similar to the stream draining stormwater management systems, for N exports. However, nitrate isotope data suggested that 55 ± 1 % of the nitrate in the urban restored stream was derived from leaky sanitary sewers (during baseflow), statistically similar to the urban degraded streams. These isotopic results as well as additional tracers, including fluoride (added to drinking water) and iodide (contained in dietary salt

  6. DISCOVERY OF THE SECOND WARM CARBON-CHAIN-CHEMISTRY SOURCE, IRAS15398 - 3359 IN LUPUS

    SciTech Connect

    Sakai, Nami; Yamamoto, Satoshi; Sakai, Takeshi; Hirota, Tomoya; Burton, Michael

    2009-05-20

    We have conducted a search for carbon-chain molecules toward 16 protostars with the Mopra 22 m and Nobeyama 45 m telescopes, and have detected high excitation lines from several species, such as C{sub 4}H (N = 9-8), C{sub 4}H{sub 2}(J = 10{sub 0,10}-9{sub 0,9}), CH{sub 3}CCH(J = 5-4, K = 2), and HC{sub 5}N(J = 32-31), toward the low-mass protostar, IRAS15398 - 3359 in Lupus. The C{sub 4}H line is as bright as 2.4 K measured with the Nobeyama 45 m telescope. The kinetic temperature is derived to be 12.6 {+-} 1.5 K from the K = 1 and K = 2 lines of CH{sub 3}CCH. These results indicate that the carbon-chain molecules exist in a region of warm and dense gas near the protostar. The observed features are similar to those found toward IRAS04368+2557 in L1527, which shows warm carbon-chain chemistry (WCCC). In WCCC, carbon-chain molecules are produced efficiently by the evaporation of CH{sub 4} from the grain mantles in a lukewarm region near the protostar. Our data clearly indicate that WCCC is no longer specific to L1527, but occurs in IRAS15398 - 3359. In addition, we draw attention to a remarkable contrast between WCCC and hot corino chemistry in low-mass star-forming regions. Carbon-chain molecules are deficient in hot corino sources like NGC1333 IRAS4B, whereas complex organic molecules seem to be less abundant in the WCCC sources. A possible origin for such source-to-source chemical variations is suggested to arise from the timescale of the starless-core phase in each source. If this is the case, the chemical composition provides an important clue to explore the variation of star formation processes between sources and/or molecular clouds.

  7. Enhanced photoluminescence and characterization of multicolor carbon dots using plant soot as a carbon source.

    PubMed

    Tan, Mingqian; Zhang, Lingxin; Tang, Rong; Song, Xiaojie; Li, Yimin; Wu, Hao; Wang, Yanfang; Lv, Guojun; Liu, Wanfa; Ma, Xiaojun

    2013-10-15

    Carbon dots (C-dots) are a class of novel fluorescent nanomaterials, which have drawn great attention for their potential applications in bio-nanotechnology. Multicolor C-dots have been synthesized by chemical nitric acid oxidation using the reproducible plant soot as raw material. TEM analysis reveals that the prepared C-dots have an average size of 3.1 nm. The C-dots are well dispersed in aqueous solution and are strongly fluorescent under the irradiation of ultra-violet light. X-ray photoelectron spectroscopy characterization demonstrates that the O/C atomic ratio for C-dots change to from 0.207 to 0.436 due to the chemical oxidation process. The photo bleaching experiment reveals that the C-dots show excellent photostability as compared with the conventional organic dyes, fluorescein and rhodamine B. The fluorescence intensity of the C-dots did not change significantly in the pH range of 3-10. To further enhance the fluorescence quantum yield, the C-dots were surface modified with four types of passivation ligands, 4,7,10-trioxa-1,13-tridecanediamine (TTDDA), poly-L-lysine (PLL), cysteine and chitosan and the fluorescence quantum yields of the TTDDA, PLL, cysteine and chitosan passivated C-dots were improved 1.53-, 5.94-, 2.00- and 3.68-fold, respectively. Fourier-transform infrared (FTIR) spectra were employed to characterize the surface groups of the C-dots. The bio-application of the C-dots as fluorescent bio-probes was evaluated in cell imaging and ex vivo fish imaging, which suggests that the C-dots may have potential applications in biolabeling and bioimaging.

  8. Carbon source--a strong determinant of microbial community structure and performance of an anaerobic reactor.

    PubMed

    Kundu, K; Bergmann, I; Hahnke, S; Klocke, M; Sharma, S; Sreekrishnan, T R

    2013-12-01

    Industrial effluents differ in their organic composition thereby providing different carbon sources to the microbial communities involved in its treatment. This study aimed to investigate the correlation of microbial community structure with wastewater composition and reactor's performance. Self-immobilized granules were developed in simulated wastewater based on different carbon sources (glucose, sugarcane molasses, and milk) in three hybrid anaerobic reactors operated at 37°C. To study archaeal community structure, a polyphasic approach was used with both qualitative and quantitative analysis. While PCR-denaturing gradient gel electrophoresis of 16S rRNA gene did not reveal major shifts in diversity of archaea with change in substrate, quantification of different groups of methanogens and total bacteria by real-time PCR showed variations in relative abundances with the dominance of Methanosaetaceae and Methanobacteriales. These data were supported by differences in the ratio of total counts of archaea and bacteria analyzed by catalyzed reporter deposition - fluorescence in situ hybridization. During hydraulic and organic shocks, the molasses-based reactor showed the best performance followed by the milk- and the glucose-based reactor. The study indicates that carbon source shapes the microbial community structure more in terms of relative abundance with distinct metabolic capacities rather than its diversity itself.

  9. Carbon source utilization and inhibitor tolerance of 45 oleaginous yeast species.

    PubMed

    Sitepu, Irnayuli; Selby, Tylan; Lin, Ting; Zhu, Shirley; Boundy-Mills, Kyria

    2014-07-01

    Conversion of lignocellulosic hydrolysates to lipids using oleaginous (high lipid) yeasts requires alignment of the hydrolysate composition with the characteristics of the yeast strain, including ability to utilize certain nutrients, ability to grow independently of costly nutrients such as vitamins, and ability to tolerate inhibitors. Some combination of these characteristics may be present in wild strains. In this study, 48 oleaginous yeast strains belonging to 45 species were tested for ability to utilize carbon sources associated with lignocellulosic hydrolysates, tolerate inhibitors, and grow in medium without supplemented vitamins. Some well-studied oleaginous yeast species, as well as some that have not been frequently utilized in research or industrial production, emerged as promising candidates for industrial use due to ability to utilize many carbon sources, including Cryptococcus aureus, Cryptococcus laurentii, Hannaella aff. zeae, Tremella encephala, and Trichosporon coremiiforme. Other species excelled in inhibitor tolerance, including Candida aff. tropicalis, Cyberlindnera jadinii, Metschnikowia pulcherrima, Schwanniomyces occidentalis and Wickerhamomyces ciferrii. No yeast tested could utilize all carbon sources and tolerate all inhibitors tested. These results indicate that yeast strains should be selected based on characteristics compatible with the composition of the targeted hydrolysate. Other factors to consider include the production of valuable co-products such as carotenoids, availability of genetic tools, biosafety level, and flocculation of the yeast strain. The data generated in this study will aid in aligning yeasts with compatible hydrolysates for conversion of carbohydrates to lipids to be used for biofuels and other oleochemicals.

  10. Carbon source utilization and inhibitor tolerance of 45 oleaginous yeast species

    PubMed Central

    Sitepu, Irnayuli; Selby, Tylan; Lin, Ting; Zhu, Shirley; Boundy-Mills, Kyria

    2014-01-01

    Conversion of lignocellulosic hydrolysates to lipids using oleaginous (high lipid) yeasts requires alignment of the hydrolysate composition with the characteristics of the yeast strain, including ability to utilize certain nutrients, ability to grow independently of costly nutrients such as vitamins, and ability to tolerate inhibitors. Some combination of these characteristics may be present in wild strains. In this study, 48 oleaginous yeast strains belonging to 45 species were tested for ability to utilize carbon sources associated with lignocellulosic hydrolysates, tolerate inhibitors, and grow in medium without supplemented vitamins. Some well-studied oleaginous yeast species, as well as some that have not been frequently utilized in research or industrial production, emerged as promising candidates for industrial use due to ability to utilize many carbon sources, including Cryptococcus aureus, Cryptococcus laurentii, Hanaella aff. zeae, Tremella encephala, and Trichosporon coremiiforme. Other species excelled in inhibitor tolerance, including Candida aff. tropicalis, Cyberlindnera jadinii, Metschnikowia pulcherrima Schwanniomyces occidentalis and Wickerhamomyces ciferii. No yeast tested could utilize all carbon sources and tolerate all inhibitors tested. These results indicate that yeast strains should be selected based on characteristics compatible with the composition of the targeted hydrolysate. Other factors to consider include the production of valuable co-products such as carotenoids, availability of genetic tools, biosafety level, and flocculation of the yeast strain. The data generated in this study will aid in aligning yeasts with compatible hydrolysates for conversion of carbohydrates to lipids to be used for biofuels and other oleochemicals. PMID:24818698

  11. Carbon and Nitrogen Sources Influence Tricalcium Phosphate Solubilization and Extracellular Phosphatase Activity by Talaromyces flavus.

    PubMed

    Stefanoni Rubio, P J; Godoy, M S; Della Mónica, I F; Pettinari, M J; Godeas, A M; Scervino, J M

    2016-01-01

    The aim of this work was to study phosphate (P) solubilization (and the processes involved in this event) by Talaromyces flavus (BAFC 3125) as a function of carbon and/or nitrogen sources. P solubilization was evaluated in NBRIP media supplemented with different carbon (glucose, sorbitol, sucrose, and fructose) and nitrogen (L-asparagine, urea, ammonium sulfate (AS), and ammonium nitrate (AN) combinations. The highest P solubilization was related to the highest organic acid production (especially gluconic acid) and pH drop for those treatments where glucose was present. Also P solubilization was higher when an inorganic nitrogen source was supplemented to the media when compared to an organic one. Although not being present an organic P source, phosphatase activity was observed. This shows that P mineralization and P solubilization can occur simultaneously, and that P mineralization is not induced by the enzyme substrate. The combination that showed highest P solubilization was for AN-glucose. The highest acid phosphatase activity was for AS-fructose, while for alkaline phosphatase were for AS-fructose and AN-fructose. Acid phosphatase activity was higher than alkaline. P solubilization and phosphatase activity (acid and alkaline) were influenced by the different carbon-nitrogen combinations. A better understanding of phosphate-solubilizing fungi could bring a better use of soil P.

  12. Sources of black carbon in aerosols: fossil fuel burning vs. biomass burning

    NASA Astrophysics Data System (ADS)

    Hsieh, Y.

    2013-12-01

    The uncertainty in black carbon (BC) analysis and our inability to directly quantify the BC sources in the atmosphere has led to the uncertainty in compiling a regional or global BC emission inventory attributed to biomass burnings. We initiate this study to demonstrate a new approach, which quantifies the source of BC in the atmosphere between biomass and fossil fuel burnings. We applied the newly developed multi-element scanning thermal analysis (MESTA) technology to quantify BC and organic carbon (OC), respectively, in aerosol samples. MESTA can also separate BC from OC for subsequent radiocarbon analyses. Because fossil fuel has been depleted of radiocarbon and biomass has radiocarbon of the modern atmospheric level, we can quantify the sources of BC between fossil fuel and biomass burnings. We sampled the PM2.5 in the ambient air of central Tallahassee and its rural areas during the May-June (prescribed burning) and Nov-Dec (non-burning) periods. The results indicate that biomass burning contributed 89×1% and 67×2% of BC, respectively, during May-June and Nov.-Dec. periods. The rest of PM2.5 BC was contributed from fossil fuel burning. The radiocarbon contents of the OC was 103.42×0.55 percent modern carbon (pmC), which is consistent with the current atmospheric level with a trace of the bomb radiocarbon remained from the open atmosphere nuclear testing.

  13. Preparation of molybdenum carbides with multiple morphologies using surfactants as carbon sources

    SciTech Connect

    Wang, Hongfen; Wang, Zhiqi; Chen, Shougang

    2012-10-15

    Molybdenum carbides with surfactants as carbon sources were prepared using the carbothermal reduction of the appropriate precursors (molybdenum oxides deposited on surfactant micelles) at 1023 K under hydrogen gas. The carburized products were characterized using scanning electron microscopy (SEM), X-ray diffraction and BET surface area measurements. From the SEM images, hollow microspherical and rod-like molybdenum carbides were observed. X-ray diffraction patterns showed that the annealing time of carburization had a large effect on the conversion of molybdenum oxides to molybdenum carbides. And BET surface area measurements indicated that the difference of carbon sources brought a big difference in specific surface areas of molybdenum carbides. - Graphical abstract: Molybdenum carbides having hollow microspherical and hollow rod-like morphologies that are different from the conventional monodipersed platelet-like morphologies. Highlights: Black-Right-Pointing-Pointer Molybdenum carbides were prepared using surfactants as carbon sources. Black-Right-Pointing-Pointer The kinds of surfactants affected the morphologies of molybdenum carbides. Black-Right-Pointing-Pointer The time of heat preservation at 1023 K affected the carburization process. Black-Right-Pointing-Pointer Molybdenum carbides with hollow structures had larger specific surface areas.

  14. Tundra ecosystems observed to be CO2 sources due to differential amplification of the carbon cycle.

    PubMed

    Belshe, E F; Schuur, E A G; Bolker, B M

    2013-10-01

    Are tundra ecosystems currently a carbon source or sink? What is the future trajectory of tundra carbon fluxes in response to climate change? These questions are of global importance because of the vast quantities of organic carbon stored in permafrost soils. In this meta-analysis, we compile 40 years of CO2 flux observations from 54 studies spanning 32 sites across northern high latitudes. Using time-series analysis, we investigated if seasonal or annual CO2 fluxes have changed over time, and whether spatial differences in mean annual temperature could help explain temporal changes in CO2 flux. Growing season net CO2 uptake has definitely increased since the 1990s; the data also suggest (albeit less definitively) an increase in winter CO2 emissions, especially in the last decade. In spite of the uncertainty in the winter trend, we estimate that tundra sites were annual CO2 sources from the mid-1980s until the 2000s, and data from the last 7 years show that tundra continue to emit CO2 annually. CO2 emissions exceed CO2 uptake across the range of temperatures that occur in the tundra biome. Taken together, these data suggest that despite increases in growing season uptake, tundra ecosystems are currently CO2 sources on an annual basis.

  15. Effect of different carbon sources on morphology and silver accumulation in Cochliobolus lunatus.

    PubMed

    Salunkhe, Rahul B; Borase, Hemant P; Patil, Chandrashekhar D; Patil, Sucheta N; Patil, Satish V

    2015-12-01

    The morphology of filamentous fungi plays very important role in uptake of metabolites and enzyme production. A filamentous fungus may be fibrous, hyphae, pellets, clumps, etc. Cochliobolus lunatus is a fungus which has previously been reported for silver accumulation and nanoparticles formation. The present study investigated the role of various carbon sources on morphology, biochemical profile, silver accumulation, and biosynthesis of silver nanoparticles by fungal strain C. lunatus. In this investigation, effect of different carbon sources was studied on morphology of C. lunatus and its silver accumulating ability. As a result of different carbon sources like carboxymethyl cellulose (CMC), pectin, starch, agar, sucrose, and mannitol, the organism showed three kinds of morphologies like homogenous smooth branched clumps, tough short fibrous filaments, and tough pellets, as well as silver accumulating ability. Atomic absorption spectroscopy (AAS) studies showed maximum uptake of Ag(+): 87.44 ± 0.23 and 82.57 ± 0.19 % in pectin- and CMC-grown biomass, respectively. The crystalline nature of silver nanoparticles (AgNPs) was confirmed by X-ray diffraction studies. Transmission electron microscopy (TEM) micrographs of silver nanoparticles confirmed size ranging from 5 to 38 nm.

  16. [Effects of carbon sources, temperature and electron acceptors on biological phosphorus removal].

    PubMed

    Han, Yun; Xu, Song; Dong, Tao; Wang, Bin-Fan; Wang, Xian-Yao; Peng, Dang-Cong

    2015-02-01

    Effects of carbon sources, temperature and electron acceptors on phosphorus uptake and release were investigated in a pilot-scale oxidation ditch. Phosphorus uptake and release rates were measured with different carbon sources (domestic sewage, sodium acetate, glucose) at 25 degrees C. The results showed that the minimum phosphorus uptake and release rates of glucose were 5.12 mg x (g x h)(-1) and 6.43 mg x (g x h)(-1), respectively, and those of domestic sewage are similar to those of sodium acetate. Phosphorus uptake and release rates increased with the increase of temperature (12, 16, 20 and 25 degrees C) using sodium acetate as carbon sources. Anoxic phosphorus uptake rate decreased with added COD. Electron acceptors (oxygen, nitrate, nitrite) had significant effects on phosphorus uptake rate and their order was in accordance with oxygen > nitrate > nitrite. The mass ratio of anoxic P uptake and N consumption (P(uptake)/N (consumption)) of nitrate and nitrite were 0.96 and 0.65, respectively.

  17. [Nitrate removal from recirculating aquaculture system using polyhydroxybutyrate-co-hydroxyvalerate as carbon source ].

    PubMed

    Zhang, Lanhe; Liu, Lili; Qiu, Tianlei; Gao, Min; Han, Meilin; Yuan, Ding; Wang, Xuming

    2014-09-04

    [ OBJECTIVE] Polyhydroxybutyrate-co-hydroxyvalerate (PHBV) was used as solid carbon source and biofilm carrier to remove nitrate from recirculating aquaculture system (RAS). Dynamics of microbial community structure in biofilm coating on carbon source packed into denitrification reactor were investigated. [METHODS] Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the microbial community in biofilm from denitrifiation reactor. Bacteria degrading PHBV were isolated from the reactor using pure culture method. [RESULTS] Nitrate decreased remarkably in the RAS connected with dentrification reactor. In contrast, Nitrate increased continuously in the conventional RAS without dentrification reactor. According to the phylogenetic analysis, the microbes in the biofilm samples from denitrification reactor were divided into Proteobacteria ( p-proteobacteria, γ-proteobacteria and δ- proteobacteria) , Firmicutes and Bacteroidetes. The major advantageous populations were Acidovorax and Bacillus in the 40-day reactor. The advantageous populations in the 150-day reactor were in order of Clostridium, Desulfitobacterium, Dechloromonas, Pseudoxanthomonas and Flavobacterium. Pure cultures of bacteria degrading PHBV isolated from denitrification reactor were classified into Acidovorax, Methylibium, Pseudoxanthomonas and Dechloromonas. [CONCLUSION] Nitrate could be removed effectively from RAS using PHBV as carbon source. Advantageous bacteria and their dynamic changes were ascertained in biofilm from denitrification reactor packed with PHBV.

  18. An update on source-to-sink carbon partitioning in tomato

    PubMed Central

    Osorio, Sonia; Ruan, Yong-Ling; Fernie, Alisdair R.

    2014-01-01

    Plant growth and carbon metabolism are closely associated since carbohydrate in the form of sucrose generated by photosynthesis, provides the primary source of building blocks and energy for the production and maintenance of biomass. Regulation of carbon partitioning between source and sink tissues is important because it has a vast influence on both plant growth and development. The regulation of carbon partitioning at the whole plant level is directly linked to the cellular pathways of assimilate transport and the metabolism and allocation of sugars, mainly sucrose and hexoses in source leaves, and sink organs such as roots and fruit. By using tomato plant as a model, this review documents and discusses our current understanding of source–sink interactions from molecular to physiological perspectives focusing on those that regulate the growth and development of both vegetative and reproductive organs. It furthermore discusses the impact that environmental conditions play in maintenance of this balance in an attempt to address the link between physiological and ecological aspects of growth. PMID:25339963

  19. Carbon and Nitrogen Sources for Shrimp Postlarvae Fed Natural Diets from a Tropical Mangrove System

    NASA Astrophysics Data System (ADS)

    Dittel, A. I.; Epifanio, C. E.; Cifuentes, L. A.; Kirchman, D. L.

    1997-11-01

    Postlarvae ofPenaeus vannameiwere fed various diets in order to examine the importance of detritus and other possible prey items in supporting postlarval growth. Stable isotopes (C and N) were used to determine the carbon and nitrogen source of the prey in the various diets. The zooplankton diet contained mostly copepods. The subtidal detritus treatment consisted mostly of plant material whereas the diets from both intertidal sites contained a mixture of plant detritus and associated meiofauna. Postlarvae reared on zooplankton and detritus plus meiofauna diets more than tripled their weight during a 6-day period. In contrast, postlarvae fed the detritus diet barely doubled their weight. Based on isotopic composition, postlarvae appear to obtain their carbon and nitrogen from various food sources. Postlarvae were enriched by 0·4‰ in13C and 2·7‰ in15N relative to the zooplankton diet, which is consistent with isotopic fractionation between successive trophic levels. In turn, the isotopic signal of the zooplankton was consistent with phytoplankton being the initial source of organic matter. In contrast, mean δ13C values of the shrimp fed detritus plus meiofauna were significantly different from their respective diets. Isotopic ratios of the postlarvae fed the mixed diet from Chomes were two trophic levels above benthic algae suggesting that the shrimp preyed on organisms that derived their carbon and nitrogen from benthic algae and/or phytoplankton.

  20. PM 2.5 source profiles for black and organic carbon emission inventories

    NASA Astrophysics Data System (ADS)

    Chow, Judith C.; Watson, John G.; Lowenthal, Douglas H.; Antony Chen, L.-W.; Motallebi, Nehzat

    2011-10-01

    Emission inventories for black or elemental (BC or EC) and organic (OC) carbon can be derived by multiplying PM 2.5 emission estimates by mass fractions of these species in representative source profiles. This study examines the variability of source profiles and its effect on EC emission estimates. An examination of available profiles shows that EC and OC ranged from 6-13% and 35-40% for agricultural burning, 4-33% and 22-68% for residential wood combustion, 6-38% and 24-75% for on-road gasoline vehicles, and 33-74% and 20-47% for on-road heavy-duty diesel vehicles, respectively. Source profiles from the U.S. EPA SPECIATE data base were applied to PM 2.5 emissions from the U.S. EPA National Emissions Inventory for 2005. The total estimated EC emissions of 432 Gg yr -1 was apportioned as 42.5% from biomass burning, 35.4% from non-road mobile sources, 15% from on-road mobile sources, 5.4% from fossil fuel (e.g., coal, oil, and natural gas) combustion in stationary sources, 1% from other stationary industrial sources, and 0.5% from fugitive dust. Considering the variability in available source profiles, BC emission estimates for major sources such as open fires and non-road diesels ranged from 42 to 133 (a factor of 3) and 25 to 100 (a factor of 4) Gg yr -1, respectively. The choice of source profiles can be a major source of uncertainty in national and global BC/EC emission inventories.

  1. Variable source areas of runoff generation: influence on soil carbon stocks

    NASA Astrophysics Data System (ADS)

    Salemi, L.; Costa Silva, R. W.; Andrade, T. M.; Fernandes, R. P.; De Moraes, J.; Camargo, P. B.; Martinelli, L.

    2013-12-01

    Variable source areas (VSA) might be considered the main mechanism of runoff generation within humid areas. In this paper we assess the soil carbon stocks within 3 flow convergence zones (FCZs) under high influence of overland-flow (OV). These FCZs had different land-cover (riparian forest and sugarcane plantations) and were subdivided into 3 portions, that is downslope, middleslope and upslope (FCZ-1 and 2: downslope - forest; middleslope and upslope -sugarcane; FCZ-3 downslope and middleslope - forest; upslope -sugarcane). Stocks under riparian forests (FCZ-1) were significantly higher than under sugarcane plantations. More importantly, riparian forests under high OV influence (FCZ-3) presented lower soil carbon stocks compared to riparian forests under lower OV influence. Similarly, sugarcane plantations within high OV areas presented in some cases (FCZ-2) significantly lower carbon stocks compared to sugarcane areas under low OV influence. These results suggest that OV within VSAs is a major driver for particulate carbon fluxes from terrestrial to aquatic ecosystems or for carbon redistribution within riparian ecosystems.

  2. Utilization of glyphosate as phosphate source: biochemistry and genetics of bacterial carbon-phosphorus lyase.

    PubMed

    Hove-Jensen, Bjarne; Zechel, David L; Jochimsen, Bjarne

    2014-03-01

    After several decades of use of glyphosate, the active ingredient in weed killers such as Roundup, in fields, forests, and gardens, the biochemical pathway of transformation of glyphosate phosphorus to a useful phosphorus source for microorganisms has been disclosed. Glyphosate is a member of a large group of chemicals, phosphonic acids or phosphonates, which are characterized by a carbon-phosphorus bond. This is in contrast to the general phosphorus compounds utilized and metabolized by microorganisms. Here phosphorus is found as phosphoric acid or phosphate ion, phosphoric acid esters, or phosphoric acid anhydrides. The latter compounds contain phosphorus that is bound only to oxygen. Hydrolytic, oxidative, and radical-based mechanisms for carbon-phosphorus bond cleavage have been described. This review deals with the radical-based mechanism employed by the carbon-phosphorus lyase of the carbon-phosphorus lyase pathway, which involves reactions for activation of phosphonate, carbon-phosphorus bond cleavage, and further chemical transformation before a useful phosphate ion is generated in a series of seven or eight enzyme-catalyzed reactions. The phn genes, encoding the enzymes for this pathway, are widespread among bacterial species. The processes are described with emphasis on glyphosate as a substrate. Additionally, the catabolism of glyphosate is intimately connected with that of aminomethylphosphonate, which is also treated in this review. Results of physiological and genetic analyses are combined with those of bioinformatics analyses.

  3. Isotopic Analysis of Sporocarp Protein and Structural Material Improves Resolution of Fungal Carbon Sources

    PubMed Central

    Chen, Janet; Hofmockel, Kirsten S.; Hobbie, Erik A.

    2016-01-01

    Fungal acquisition of resources is difficult to assess in the field. To determine whether fungi received carbon from recent plant photosynthate, litter or soil-derived organic (C:N bonded) nitrogen, we examined differences in δ13C among bulk tissue, structural carbon, and protein extracts of sporocarps of three fungal types: saprotrophic fungi, fungi with hydrophobic ectomycorrhizae, or fungi with hydrophilic ectomycorrhizae. Sporocarps were collected from experimental plots of the Duke Free-air CO2 enrichment experiment during and after CO2 enrichment. The differential 13C labeling of ecosystem pools in CO2 enrichment experiments was tracked into fungi and provided novel insights into organic nitrogen use. Specifically, sporocarp δ13C as well as δ15N of protein and structural material indicated that fungi with hydrophobic ectomycorrhizae used soil-derived organic nitrogen sources for protein carbon, fungi with hydrophilic ectomycorrhizae used recent plant photosynthates for protein carbon and both fungal groups used photosynthates for structural carbon. Saprotrophic fungi depended on litter produced during fumigation for both protein and structural material. PMID:28082951

  4. Utilization of Glyphosate as Phosphate Source: Biochemistry and Genetics of Bacterial Carbon-Phosphorus Lyase

    PubMed Central

    Zechel, David L.; Jochimsen, Bjarne

    2014-01-01

    SUMMARY After several decades of use of glyphosate, the active ingredient in weed killers such as Roundup, in fields, forests, and gardens, the biochemical pathway of transformation of glyphosate phosphorus to a useful phosphorus source for microorganisms has been disclosed. Glyphosate is a member of a large group of chemicals, phosphonic acids or phosphonates, which are characterized by a carbon-phosphorus bond. This is in contrast to the general phosphorus compounds utilized and metabolized by microorganisms. Here phosphorus is found as phosphoric acid or phosphate ion, phosphoric acid esters, or phosphoric acid anhydrides. The latter compounds contain phosphorus that is bound only to oxygen. Hydrolytic, oxidative, and radical-based mechanisms for carbon-phosphorus bond cleavage have been described. This review deals with the radical-based mechanism employed by the carbon-phosphorus lyase of the carbon-phosphorus lyase pathway, which involves reactions for activation of phosphonate, carbon-phosphorus bond cleavage, and further chemical transformation before a useful phosphate ion is generated in a series of seven or eight enzyme-catalyzed reactions. The phn genes, encoding the enzymes for this pathway, are widespread among bacterial species. The processes are described with emphasis on glyphosate as a substrate. Additionally, the catabolism of glyphosate is intimately connected with that of aminomethylphosphonate, which is also treated in this review. Results of physiological and genetic analyses are combined with those of bioinformatics analyses. PMID:24600043

  5. Using U-series Isotopes To Determine Sources Of Pedogenic Carbonates: Comparison Of Natural And Agricultural Soils In The Semi-arid Southern New Mexico And Western Texas

    NASA Astrophysics Data System (ADS)

    Nyachoti, S. K.; Ma, L.; Borrok, D. M.; Jin, L.; Tweedie, C. E.

    2012-12-01

    Pedogenic carbonates commonly precipitate from infiltrating soil water in arid and semi-arid lands and are observed in soils of southern New Mexico and western Texas. These carbonates could form an impermeable layer in the soil horizons impairing water infiltration, thus affecting crop growth and yield. It is important to determine the source of C and Ca in these carbonates and to understand conditions favoring their formation, kinetics and precipitation rates. In this study, major elements and U-series isotopes in bulk calcic soils, and weak acid leachates and residues were measured from one irrigated alfalfa site in the Hueco basin near El Paso, TX and one natural shrubland site on the USDA Jornada experimental range in southern NM. The combined geochemical and isotopic results allow us to determine the formation ages of the carbonates; investigate the mobility of U, Th, and major elements in these soils; and infer for the effects of irrigation on carbonate formation in agricultural soils. Our results show distinctive U and Th isotope systems in the two soil profiles analyzed. For example, (234U/238U) ratios in the Jornada bulk soils decrease from ~1.01 to 0.96 towards the surface, consistent with a preferential loss of 234U over 238U during chemical weathering. At the Jornada site, (238U/232Th) ratios decrease while (230Th/238U) increase towards the surface, consistent with a general depletion of U and the immobility of Th in the natural soils. By contrast at the Alfalfa site, (234U/238U) ratios of bulk soils increase from ~ 0.97 to 1.02 towards the surface, suggesting an additional source of external uranium, most likely the irrigation water from Rio Grande which has a (234U/238U) ratio of ~ 1.5 near El Paso. The (238U/232Th) and (230Th/238U) ratios also imply leaching of U from shallower soils but precipitation in greater depths at Alfalfa site; suggests that partial dissolution and re-precipitation of younger carbonates occur. Calculated carbonate ages from U

  6. Biosynthesis of poly(3-hydroxybutyrate) (PHB) by Cupriavidus necator H16 from jatropha oil as carbon source.

    PubMed

    Batcha, Abeed Fatima Mohidin; Prasad, D M Reddy; Khan, Maksudur R; Abdullah, Hamidah

    2014-05-01

    Poly(3-hydroxybutyrate) (PHB) is a biodegradable polymer that can be synthesized through bacterial fermentation. In this study, Cupriavidus necator H16 is used to synthesize PHB by using Jatropha oil as its sole carbon source. Different variables mainly jatropha oil and urea concentrations, and agitation rate were investigated to determine the optimum condition for microbial fermentation in batch culture. Based on the results, the highest cell dry weight and PHB concentrations of 20.1 and 15.5 g/L, respectively, were obtained when 20 g/L of jatropha oil was used. Ethanol was used as external stress factor and the addition of 1.5 % ethanol at 38 h had a positive effect with a high PHB yield of 0.987 g PHB/g jatropha oil. The kinetic studies for cell growth rate and PHB production were conducted and the data were fitted with Logistic and Leudeking–Piret models. The rate constants were evaluated and the theoretical values were in accordance with the experimental data obtained

  7. Temporal variations in sources and concentrations of black and organic carbon aerosols in the LA Basin

    NASA Astrophysics Data System (ADS)

    Mouteva, G.; Kearney, J.; Fahrni, S.; Santos, G. M.; Czimczik, C. I.

    2012-12-01

    Temporal variations in sources and concentrations of black and organic carbon aerosols in the LA Basin Black carbon (BC), derived from incomplete combustion of fossil and biogenic fuels and vegetation fires, is a crucial component of the aerosol pool, but sources as well as atmospheric transport and lifetime remain poorly constrained by measurements. We characterized the composition of carbonaceous aerosols emitted from urban areas by quantifying the temporal variations in the concentrations and sources of BC and organic carbon (OC) in PM-10 and PM-2.5 from two locations in the Los Angeles basin. Using the radiocarbon signatures in BC and OC allowed us to apportion emissions into fossil and modern contributions. We separated and quantified BC and OC using a modified Sunset OC-EC analyzer coupled to a vacuum line and cryogenically trapped the evolving CO2 (Zhang et al. In Prep.). The instrument and method were tested with well-defined radiocarbon standards to determine background, accuracy and precision. The purified CO2 was converted to graphite and measured at the Keck-AMS facility on unknown samples as small as ≥5 μg C. Preliminary results suggest that radiocarbon content can be used to apportion BC into fossil and modern sources. BC concentrations are on the order of 6-31% total carbon, with 48 to 96% fossil contribution. In the OC fraction we detected several super-modern samples, suggesting local production of radiocarbon, e.g. from medical waste incinerators. Thus, the radiocarbon-based approach cannot be used to quantify sources of OC and bulk carbonaceous aerosols in urban areas. Our measurements contribute to a comprehensive quantification of temporal and spatial variations in urban BC, a key uncertainty in constraining BC sources and transport in North America. References: Zhang YL, Perron N, Zotter P, Minguillón MC, Wacker L, Prévôt ASH, Baltensperger U, Szidat S. In Prep. On the isolation of OC and EC and the optimal strategy of radiocarbon

  8. Stable carbon isotope ratios of intact GDGTs indicate heterogeneous sources to marine sediments

    NASA Astrophysics Data System (ADS)

    Pearson, Ann; Hurley, Sarah J.; Walter, Sunita R. Shah; Kusch, Stephanie; Lichtin, Samantha; Zhang, Yi Ge

    2016-05-01

    Thaumarchaeota, the major sources of marine glycerol dibiphytanyl glycerol tetraether lipids (GDGTs), are believed to fix the majority of their carbon directly from dissolved inorganic carbon (DIC). The δ13C values of GDGTs (δ13CGDGT) may be powerful tools for reconstructing variations in the ocean carbon cycle, including paleoproductivity and water mass circulation, if they can be related to values of δ13CDIC. To date, isotope measurements primarily are made on the C40 biphytane skeletons of GDGTs, rather than on complete tetraether structures. This approach erases information revealed by the isotopic heterogeneity of GDGTs within a sample and may impart an isotopic fractionation associated with the ether cleavage. To circumvent these issues, we present δ13C values for GDGTs from twelve recent sediments representing ten continental margin locations. Samples are purified by orthogonal dimensions of HPLC, followed by measurement of δ13C values by Spooling Wire Microcombustion (SWiM)-isotope ratio mass spectrometry (IRMS) with 1σ precision and accuracy of ±0.25‰. Using this approach, we confirm that GDGTs, generally around -19‰, are isotopically "heavy" compared to other marine lipids. However, measured δ13CGDGT values are inconsistent with predicted values based on the 13C content of DIC in the overlying water column and the previously-published biosynthetic isotope fractionation for a pure culture of an autotrophic marine thaumarchaeon. In some sediments, the isotopic composition of individual GDGTs differs, indicating multiple source inputs. The data appear to confirm that crenarchaeol primarily is a biomarker for Thaumarchaeota, but its δ13C values still cannot be explained solely by autotrophic carbon fixation. Overall the complexity of the results suggests that both organic carbon assimilation (ca. 25% of total carbon) and multiple source(s) of exogenous GDGTs (contributing generally <30% of input to sediments) are necessary to explain the observed

  9. [Characteristics and sources of organic carbon and elemental carbon in PM2.5 in Shanghai urban area].

    PubMed

    Zhang, Yi-hua; Wang, Dong-fang; Zhao, Qian-biao; Cui, Hu-xiong; Li, Juan; Duan, Yu-sen; Fu, Qing-yan

    2014-09-01

    Organic carbon (OC) and elemental carbon (EC) in PM2.5 samples collected in Shanghai urban area during June 2010 to May 2011 were analyzed with IMPROVE-TOR protocol. The results showed that the annual average concentrations of OC and EC in PM2.5 were 8.6 μg.m-3 ± 6.2 μg.m-3 and 2.4 μg.m-3 ± 1.3 μg.m-3 respectively, accounting for 20% of PM2.5 mass concentration. The seasonal average concentrations of OC and EC were highest in winter and lowest in summer. And the percentages of OC and EC in PM2.5 were highest in autumn. The annual average OC/EC ratio was 3. 54 ± 1. 14. The concentrations of secondary organic carbon (SOC) were evaluated by the minimum OC/EC ratio method and the annual average concentration of SOC was 3.9 μg.m(-3) ±4.2 μg.m(-3), accounting for 38.9% of OC. In summer, the concentrations of SOC were relatively low and were correlated well with the maximum hourly concentrations of ozone, which indicated that the photochemical reaction was an important way of SOC formation. In autumn and winter when the west wind direction was predominant, the concentrations of SOC were higher than that in windless condition, which meant the transportation of SOC. The carbonaceous components were associated with source contributions using the principal component analysis (PCA) with eight thermally-derived carbon fractions, OC1, OC2, OC3, OC4, EC1, EC2, EC3 and OPC. Motor vehicle, coal-fired units, biomass burning and road dust were four main sources of OC and EC in PM2.5 in Shanghai urban area, which contributing 69. 8% - 81. 4% of carbonaceous aerosols. The contribution of motor vehicle was high throughout the year. Biomass burning contributed about 15% -20% of OC and EC. The influence of road dust was relatively obvious in spring and autumn. And the contribution of coal-fired units was higher in winter than those in other seasons.

  10. Characterization of Wavelength-Tunable Quantum Dot External Cavity Laser for 1.3-µm-Waveband Coherent Light Sources

    NASA Astrophysics Data System (ADS)

    Yamamoto, Naokatsu; Akahane, Kouichi; Kawanishi, Tetsuya; Sotobayashi, Hideyuki; Yoshioka, Yuki; Takai, Hiroshi

    2012-02-01

    A sandwiched sub-nano separator (SSNS) growth technique of producing high-density, high-quality InAs/InGaAs quantum dot (QD) structures on GaAs substrates is proposed. The SSNS technique achieved a density of 8.2 ×1010/cm2 by suppressing giant dot formation. The QD structures fabricated by the SSNS technique were used to form a ridge-type waveguide QD optical gain chip for O-band optical gain. With this chip, we successfully demonstrated the generation of a wavelength-tunable fine-tooth optical frequency comb in the O-band from a QD optical frequency comb laser (QD-CML), and synchronized short-optical-pulse generation (˜14 ps) with gigahertz-order repetition from a hybrid mode-locked QD-CML. We also successfully demonstrated a wavelength tunable QD-ECL with a wide wavelength tuning range (1265-1320 nm) and a narrow linewidth (210 kHz) in the O-band. It is expected that these QD coherent light sources will become attractive photonic devices for many scientific applications in the 1.0-1.3 µm waveband.

  11. STABLE CARBON ISOTOPES OF HCO//3 IN THE AQUIA AQUIFER, MARYLAND: EVIDENCE FOR AN ISOTOPICALLY HEAVY SOURCE OF CO//2.

    USGS Publications Warehouse

    Chapelle, Francis H.; Knobel, LeRoy L.

    1985-01-01

    Identifying sources and sinks of dissolved inorganic carbon species is an important step in understanding the geochemistry of ground-water systems. This is particularly important for Atlantic Coastal Plain aquifers because bicarbonate (HCO//3** minus ) is frequently the major dissolved anion. The purpose of this paper is to document the stable carbon isotope composition of dissolved inorganic carbon in the Aquia aquifer, Maryland, and to use this data to help identify sources and sinks of dissolved HCO//3** minus . Subjects covered include hydrogeology, ground-water chemistry, sources and sinks, and others. Refs.

  12. Badlands and the Carbon cycle: a significant source of petrogenic organic carbon in rivers and marine environments?

    NASA Astrophysics Data System (ADS)

    Copard, Yoann; Eyrolle-Boyer, Frederique; Radakovitch, Olivier; Poirel, Alain; Raimbault, Patrick; Lebouteiller, Caroline; Gairoard, Stéphanie; Di-Giovanni, Christian

    2016-04-01

    A key issue in the study of carbon biogeochemical cycle is to well constrain each carbon origin in term of fluxes between all C-reservoirs. From continental surfaces to oceans, rivers convey particulate organic carbon originate from the biomass (biospheric OC) and /or from the sedimentary rocks (petrogenic OC). Existence and importance of this petrogenic OC export to oceans was debated for several decades (see Copard et al., 2007 and ref.), but it is now assumed that 20% of the global carbon export to ocean has a geological origin (Galy et al., 2015). The main current challenge is to constrain the major contributors to this petrogenic OC flux. Amongst the expected sedimentary sources of petrogenic OC in rivers, sedimentary rocks forming badlands can be rightly considered as some viable candidates. Indeed these rocks show a strong erosion rate, may exceed 50 kt km-2 y-1 and in addition, shales, marls and argillaceous rocks, frequently forming badlands (see Nadal-Romero et al., 2011 for the Mediterranean area), contain a significant amount of petrogenic OC (frequently over 0.50 wt. %, Ronov and Yaroshevsky 1976). Our work illustrates the contribution of badlands, mainly distributed within the Durance catchment (a main tributary of the Rhône river), in the petrogenic OC export to the Mediterranean Sea. The approach is based on (i) the use of previous and new data on radiogenic carbon, (ii) bulk organic geochemistry (Rock-Eval pyrolysis), (iii) optical quantification of particulate OM (palynofacies), performed on suspended sediments from the Durance, the Rhône rivers and from small rivers draining the badlands. A mean erosion rate of badlands, previously calculated for instrumented catchments (SOERE Draix-Bléone, Graz et al., 2012) was also applied to the badlands disseminated within the Durance catchment. These different methodologies converge to a petrogenic contribution of the OC export to the Mediterranean Sea close to 30 %. Badlands from the Durance catchment

  13. Need and seek for dietary micronutrients: endogenous regulation, external signalling and food sources of carotenoids in new world vultures.

    PubMed

    Blanco, Guillermo; Hornero-Méndez, Dámaso; Lambertucci, Sergio A; Bautista, Luis M; Wiemeyer, Guillermo; Sanchez-Zapata, José A; Garrido-Fernández, Juan; Hiraldo, Fernando; Donázar, José A

    2013-01-01

    Among birds, vultures show low concentrations of plasma carotenoids due to the combination of their large size, general dull colouration and a diet based on carrion. We recorded the concentration of each carotenoid type present in plasma of the Andean condor (Vultur gryphus) according to age and sex, that determine colour signalling and dominance hierarchies in the carcasses. We compared the carotenoid profile in wild condors with that of captive condors fed with a controlled diet of flesh to test the hypothesis that wild individuals could acquire extra carotenoids from vegetal matter contained in carcass viscera and fresh vegetation. Wild American black vultures (Coragyps atratus) were also sampled to evaluate the potential influence of colouration in the integument on absorption and accumulation patterns of plasma carotenoids. A remarkably higher concentration of lutein than β-carotene was found in wild condors, while the contrary pattern was recorded in American black vultures and captive condors. We found a consistent decrease in all plasma carotenoids with age, and a lower concentration of most xanthophylls in male compared to female wild condors. Positive correlations of all carotenoids indicated general common absorption and accumulation strategies or a single dietary source containing all pigments found in plasma. The comparatively low total concentration of carotenoids, and especially of lutein rather than β-carotene, found in captive condors fed with a diet restricted to flesh supports the hypothesis that Andean condors can efficiently acquire carotenoids from vegetal matter in the wild. Andean condors seem to be physiologically more competent in the uptake or accumulation of xanthophylls than American black vultures, which agrees with the use of colour-signalling strategies in sexual and competitive contexts in the Andean condor. This study suggests that vultures may use dietary vegetal supplements that provide pigments and micronutrients that are

  14. Need and Seek for Dietary Micronutrients: Endogenous Regulation, External Signalling and Food Sources of Carotenoids in New World Vultures

    PubMed Central

    Blanco, Guillermo; Hornero-Méndez, Dámaso; Lambertucci, Sergio A.; Bautista, Luis M.; Wiemeyer, Guillermo; Sanchez-Zapata, José A.; Garrido-Fernández, Juan; Hiraldo, Fernando; Donázar, José A.

    2013-01-01

    Among birds, vultures show low concentrations of plasma carotenoids due to the combination of their large size, general dull colouration and a diet based on carrion. We recorded the concentration of each carotenoid type present in plasma of the Andean condor (Vultur gryphus) according to age and sex, that determine colour signalling and dominance hierarchies in the carcasses. We compared the carotenoid profile in wild condors with that of captive condors fed with a controlled diet of flesh to test the hypothesis that wild individuals could acquire extra carotenoids from vegetal matter contained in carcass viscera and fresh vegetation. Wild American black vultures (Coragyps atratus) were also sampled to evaluate the potential influence of colouration in the integument on absorption and accumulation patterns of plasma carotenoids. A remarkably higher concentration of lutein than β-carotene was found in wild condors, while the contrary pattern was recorded in American black vultures and captive condors. We found a consistent decrease in all plasma carotenoids with age, and a lower concentration of most xanthophylls in male compared to female wild condors. Positive correlations of all carotenoids indicated general common absorption and accumulation strategies or a single dietary source containing all pigments found in plasma. The comparatively low total concentration of carotenoids, and especially of lutein rather than β-carotene, found in captive condors fed with a diet restricted to flesh supports the hypothesis that Andean condors can efficiently acquire carotenoids from vegetal matter in the wild. Andean condors seem to be physiologically more competent in the uptake or accumulation of xanthophylls than American black vultures, which agrees with the use of colour-signalling strategies in sexual and competitive contexts in the Andean condor. This study suggests that vultures may use dietary vegetal supplements that provide pigments and micronutrients that are

  15. Operation of an extraction, applied-B diode using an externally-driven, metallic foil anode plasma source

    SciTech Connect

    Hinshelwood, D.D.; Fisher, R.C.; Greenly, J.B.; Neri, J.M.; Oliver, B.V.; Ottinger, P.F.; Rose, D.V.; Stephanakis, S.J.; Young, F.C.

    1995-12-31

    The authors are developing an extraction, applied-B ion diode, on the Gamble II generator at NRL, for ion-beam-transport research in support of the SNL light-ion ICF program. An ion beam with a voltage above 1 MV and a proton current of 150--200 kA is required for transport experiments. At present they are using hardware which allows a maximum anode area of {approximately}60 cm{sup 2}. These parameters result in enhancement factors 2--3 times greater than those in similar experiments at Cornell, SNL, and KfK. In addition, the early, high-impedance phase of the diode must be minimized to prevent insulator flashover. Transport experiments with beam focusing also preclude ion beam angular momentum. A version of the EMFAP source, developed at Cornell and improved at KfK, is used to provide prompt turn-on of the ion current. To date the authors have obtained ion beams with rapid turn-on, high currents and current densities, high ion efficiencies (80%), relatively stable impedance behavior, and negligible angular momentum. Unfortunately, these have not all been obtained on the same shot. Electron loss current flowing through the anode foil is seen to play an important role in evolution of the anode plasma. Under the conditions of this experiment, the diode self-magnetic field is also important. Work at present centers on viewing the existing data in light of the refined field measurements, coupled with PIC modeling, to identify an operating regime that will provide the required electrical behavior without beam angular momentum.

  16. Carbon sources supporting a diverse fish community in a tropical coastal ecosystem (Gazi Bay, Kenya)

    NASA Astrophysics Data System (ADS)

    Nyunja, J.; Ntiba, M.; Onyari, J.; Mavuti, K.; Soetaert, K.; Bouillon, S.

    2009-07-01

    Interlinked mangrove-seagrass ecosystems are characteristic features of many tropical coastal areas, where they act as feeding and nursery grounds for a variety of fishes and invertebrates. The autotrophic carbon sources supporting fisheries in Gazi bay (Kenya) were studied in three sites, two located in the tidal creeks flowing through extensive mangrove forests, another site located in the subtidal seagrass meadows, approximately 2.5 km away from the forest. Carbon and nitrogen stable isotope composition of 42 fish species, 2 crustacean species and a range of potential primary food sources (e.g., mangroves, seagrasses and epiphytes, macroalgae) were analysed. There was considerable overlap in the δ 13C signatures between fish (-16.1 ± 2.1‰), seagrasses (-15.1 ± 3.0‰), seagrass epiphytes (-13.6 ± 3.3‰), and macroalgae (-20.4 ± 3.1‰). Nevertheless, the signatures for most primary producers were sufficiently distinct to indicate that the dominant carbon sources for fish were mainly derived from the seagrass and their associated epiphytic community, and possibly macroalgae. Mangrove-derived organic matter contributes only marginally to the overall fish food web. Carbon supporting these fish communities was derived directly through grazing by herbivorous and some omnivorous fishes, or indirectly through the benthic food web. Fishes from the mangrove creeks had distinctly lower δ 13C signatures (-16.8 ± 2.0‰) compared to those collected in the adjacent seagrass beds (-14.7 ± 1.7‰). This indicated that these habitats were used as distinct sheltering and feeding zones for the fishes collected, with minimal degree of exchange within the fish communities despite their regular movement pattern.

  17. Global Transcriptomic Analysis of Desulfovibrio vulgaris Grown on Different Carbon Sources

    SciTech Connect

    Zhang, Weiwen; Culley, David E.; Scholten, Johannes C.; Hogan, Mike; Vitiritti, Luigi; Brockman, Fred J.

    2006-02-01

    Abstract Whole-genome microarrays of Desulfovibrio vulgaris were used to determine relative transcript levels in cells grown to exponential or stationary phase on a minimal medium containing either lactate or formate as electron donor. The results showed that 158 and 477 genes were differentially expressed when comparing exponential to stationary phase in lactate- or formate-based media, respectively; and 505 and 355 genes were responsive to the electron donor used at exponential or stationary phase, respectively. Functional analyses suggested that genes differentially regulated were involved in almost every aspect of cellular metabolism, with the genes involved in protein synthesis, carbon, and energy metabolism being the most regulated. The results suggested that hynAB-1 might function as a primary periplasmic hydrogenase responsible for oxidation of H2 inked to the proton gradient in lactate-based medium, while several periplasmic hydrogenases including hynAB-1 and hyd might carry out this role in formate-based medium. The results also indicated the proton gradient pathway catalyzed by alcohol dehydrogenase and heterodisulfide reductase might be actively functioning for ATP synthesis in D. vulgaris. The possible pathways for ethanol generation from lactate and formate metabolism were also discussed. In addition, hierarchical clustering analysis using expression data across carbon sources and growth phases allowed the identification of the common change specifically associated with the exponential to stationary phase transition, and that specifically associated with the carbon source change from lactate to formate. The study provides the first global description and a functional interpretation of transcriptomic response to growth phase and carbon source in D. vulgaris.

  18. Importance of seagrass as a carbon source for heterotrophic bacteria in a subtropical estuary (Florida Bay)

    NASA Astrophysics Data System (ADS)

    Williams, Clayton J.; Jaffé, Rudolf; Anderson, William T.; Jochem, Frank J.

    2009-11-01

    A stable carbon isotope approach was taken to identify potential organic matter sources incorporated into biomass by the heterotrophic bacterial community of Florida Bay, a subtropical estuary with a recent history of seagrass loss and phytoplankton blooms. To gain a more complete understanding of bacterial carbon cycling in seagrass estuaries, this study focused on the importance of seagrass-derived organic matter to pelagic, seagrass epiphytic, and sediment surface bacteria. Particulate organic matter (POM), seagrass epiphytic, seagrass ( Thalassia testudinum) leaf, and sediment surface samples were collected from four Florida Bay locations with historically different organic matter inputs, macrophyte densities, and primary productivities. Bulk (observed and those reported previously) and compound-specific bacterial fatty acid δ 13C values were used to determine important carbon sources to the estuary and benthic and pelagic heterotrophic bacteria. The δ 13C values of T. testudinum green leaves with epiphytes removed ranged from -9.9 to -6.9‰. Thalassia testudinum δ 13C values were significant more enriched in 13C than POM, epiphytic, and sediment samples, which ranged from -16.4 to -13.5, -16.2 to -9.6, and -16.7 to -11.0‰, respectively. Bacterial fatty acid δ 13C values (measured for br14:0, 15:0, i15:0, a15:0, br17:0, and 17:0) ranged from -25.5 to -8.2‰. Assuming a -3‰ carbon source fractionation from fatty acid to whole bacteria, pelagic, epiphytic, and sediment bacterial δ 13C values were generally more depleted in 13C than T. testudinum δ 13C values, more enriched in 13C than reported δ 13C values for mangroves, and similar to reported δ 13C values for algae. IsoSource mixing model results indicated that organic matter derived from T. testudinum was incorporated by both benthic and pelagic bacterial communities, where 13-67% of bacterial δ 13C values could arise from consumption of seagrass-derived organic matter. The IsoSource model

  19. Development of C6+ laser ion source and RFQ linac for carbon ion radiotherapy

    NASA Astrophysics Data System (ADS)

    Sako, T.; Yamaguchi, A.; Sato, K.; Goto, A.; Iwai, T.; Nayuki, T.; Nemoto, K.; Kayama, T.; Takeuchi, T.

    2016-02-01

    A prototype C6+ injector using a laser ion source has been developed for a compact synchrotron dedicated to carbon ion radiotherapy. The injector consists of a laser ion source and a 4-vane radio-frequency quadrupole (RFQ) linac. Ion beams are extracted from plasma and directly injected into the RFQ. A solenoid guides the low-energy beams into the RFQ. The RFQ is designed to accelerate high-intensity pulsed beams. A structure of monolithic vanes and cavities is adopted to reduce its power consumption. In beam acceleration tests, a solenoidal magnetic field set between the laser ion source and the RFQ helped increase both the peak currents before and after the RFQ by a factor of 4.

  20. Development of C⁶⁺ laser ion source and RFQ linac for carbon ion radiotherapy.

    PubMed

    Sako, T; Yamaguchi, A; Sato, K; Goto, A; Iwai, T; Nayuki, T; Nemoto, K; Kayama, T; Takeuchi, T

    2016-02-01

    A prototype C(6+) injector using a laser ion source has been developed for a compact synchrotron dedicated to carbon ion radiotherapy. The injector consists of a laser ion source and a 4-vane radio-frequency quadrupole (RFQ) linac. Ion beams are extracted from plasma and directly injected into the RFQ. A solenoid guides the low-energy beams into the RFQ. The RFQ is designed to accelerate high-intensity pulsed beams. A structure of monolithic vanes and cavities is adopted to reduce its power consumption. In beam acceleration tests, a solenoidal magnetic field set between the laser ion source and the RFQ helped increase both the peak currents before and after the RFQ by a factor of 4.

  1. The cold adaptability of microorganisms with different carbon source in activated sludge treating synthetical wastewater.

    PubMed

    Niu, Chuan; Geng, Jinju; Ren, Hongqiang; Ding, Lili; Xu, Ke

    2012-11-01

    The cold adaptability of microorganisms with different carbon source under 5°C was studied in activated sludge for treating synthetical wastewater. Phospholipid fatty acid (PLFA) analysis indicated contents of unsaturated fatty acids in cell membrane at 5°C were 13.66% and 24.96% higher for glucose and sodium acetate source than that at 25°C. PLFA biomarkers showed more Gram-negative bacteria enriched than Gram-positive bacteria in low-temperature activated sludge. The Shannon-Wiener diversity analysis demonstrated glucose fed reactor in low temperature had lower PLFA diversity index (1.21-1.30) than that at 25°C and sodium acetate source was reverse (1.08-0.69). The 16S rRNA analysis manifested certain microbes were considerably suitable for existence under cold environment, most of which belong to Gram-negative bacteria.

  2. A carbon-cluster laser ion source for TRIGA-TRAP

    NASA Astrophysics Data System (ADS)

    Smorra, C.; Blaum, K.; Eberhardt, K.; Eibach, M.; Ketelaer, J.; Ketter, J.; Knuth, K.; Nagy, Sz

    2009-08-01

    A new laser ablation ion source was developed and tested for the Penning trap mass spectrometer TRIGA-TRAP in order to provide carbon-cluster ions for absolute mass calibration. Ions of different cluster sizes up to C+24 were successfully produced, covering the mass range up to the heavy actinide elements. The ions were captured in a Penning trap, and their time-of-flight cyclotron resonances recorded in order to determine their cyclotron frequency. Furthermore, the same ion source was used to produce GdO+ ions from a gadolinium target in sufficient amount for mass spectrometry purposes. The design of the source and its characteristics are presented. This paper comprises partly the PhD theses of J Ketelaer and C Smorra.

  3. Development of C{sup 6+} laser ion source and RFQ linac for carbon ion radiotherapy

    SciTech Connect

    Sako, T. Yamaguchi, A.; Sato, K.; Goto, A.; Iwai, T.; Nayuki, T.; Nemoto, K.; Kayama, T.; Takeuchi, T.

    2016-02-15

    A prototype C{sup 6+} injector using a laser ion source has been developed for a compact synchrotron dedicated to carbon ion radiotherapy. The injector consists of a laser ion source and a 4-vane radio-frequency quadrupole (RFQ) linac. Ion beams are extracted from plasma and directly injected into the RFQ. A solenoid guides the low-energy beams into the RFQ. The RFQ is designed to accelerate high-intensity pulsed beams. A structure of monolithic vanes and cavities is adopted to reduce its power consumption. In beam acceleration tests, a solenoidal magnetic field set between the laser ion source and the RFQ helped increase both the peak currents before and after the RFQ by a factor of 4.

  4. Fossil and Nonfossil Sources of Organic and Elemental Carbon Aerosols in the Outflow from Northeast China.

    PubMed

    Zhang, Yan-Lin; Kawamura, Kimitaka; Agrios, Konstantinos; Lee, Meehye; Salazar, Gary; Szidat, Sönke

    2016-06-21

    Source quantification of carbonaceous aerosols in the Chinese outflow regions still remains uncertain despite their high mass concentrations. Here, we unambiguously quantified fossil and nonfossil contributions to elemental carbon (EC) and organic carbon (OC) of total suspended particles (TSP) from a regional receptor site in the outflow of Northeast China using radiocarbon measurement. OC and EC concentrations were lower in summer, representing mainly marine air, than in other seasons, when air masses mostly traveled over continental regions in Mongolia and northeast China. The annual-mean contribution from fossil-fuel combustion to EC was 76 ± 11% (0.1-1.3 μg m(-3)). The remaining 24 ± 11% (0.03-0.42 μg m(-3)) was attributed to biomass burning, with slightly higher contribution in the cold period (∼31%) compared to the warm period (∼21%) because of enhanced emissions from regional biomass combustion sources in China. OC was generally dominated by nonfossil sources, with an annual average of 66 ± 11% (0.5-2.8 μg m(-3)), approximately half of which was apportioned to primary biomass-burning sources (34 ± 6%). In winter, OC almost equally originated from primary OC (POC) emissions and secondary OC (SOC) formation from fossil fuel and biomass-burning sources. In contrast, summertime OC was dominated by primary biogenic emissions as well as secondary production from biogenic and biomass-burning sources, but fossil-derived SOC was the smallest contributor. Distinction of POC and SOC was performed using primary POC-to-EC emission ratios separated for fossil and nonfossil emissions.

  5. Preliminary identification of ground-water nitrate sources using nitrogen and carbon stable isotopes, Kansas

    USGS Publications Warehouse

    Townsend, M.A.; Macko, S.A.

    2007-01-01

    Increasing nitrate-N in ground water is a problem in areas with limited ground-water supplies, such as central Kansas. Nitrate-N concentrations in ground water in the study area in Ellis County range from 0.9 to 26 mg/L. Calculated mean values observed in soil cores are 1.2-15 mg/kg. The ??15N signatures of the ground waters are more enriched (+16.8 to +28.7???) than those of the soils (+8.4 to +1 3.7???), strongly suggesting that nitrate-N sources are not from mineralized and labile nitrogen present in the unsaturated zone. Soil cores were collected near municipal wells to determine if soil nitrogen was a contributing source to the ground water. Increased ??15N of total nitrogen with depth suggests that microbial mineralization processes and possible denitrification or volatilization isotope enrichments have affected the observed ?? 15N signatures in the soil. However, the observed soil-nitrogen values are not of sufficient magnitude to explain the nitrate-N concentrations or associated ??15N values observed in the ground water. Stable carbon isotopes provide some supporting evidence that soils are not a major contributor to the observed nitrate-N concentration in the ground water. ?? 13C values of the dissolved organic carbon (DOC) in soils generally become more enriched with depth while corresponding ground-water ??13C (DOC) values are more depleted than in the overlying soils. Carbon isotope values of the soils are indicative of a C4 plant source that is enriched by microbial processes. The ??13C (DOC) of ground water indicates C3 values that may reflect impacts from animal-waste sources.

  6. Preparation and Physicochemical Evaluation of Controlled-release Carbon Source Tablet for Groundwater in situ Denitrification

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kang, J. H.; Yeum, Y.; Han, K. J.; Kim, D. W.; Park, C. W.

    2015-12-01

    Nitric nitrogen could be the one of typical pollution source such asNO3-through domestic sewage, livestock and agricultural wastewater. Resident microflorain aquifer has known to remove the nitric nitrogen spontaneously following the denitration process with the carbon source (CS) as reactant. However, it could be reacted very slowly with the rack of CS and there have been some studies for controlled addition of CS (Ref #1-3). The aim of this study was to prepare the controlled-release carbon source (CR-CS) tablet and to evaluate in vitro release profile for groundwater in situ denitrification. CR-CS tablet could be manufactured by direct compression method using hydraulic laboratory press (Caver® 3850) with 8 mm rounded concave punch/ die.Seven kinds of CR-CS tablet were prepared to determine the nature of the additives and their ratio such as sodium silicate, dicalcium phosphate, bentonite and sand#8.For each formulation, the LOD% and flowability of pre-mixed powders and the hardness of compressed tablets were analyzed. In vitro release study was performed to confirm the dissolution profiles following the USP Apparatus 2 method with Distilled water of 900mL, 20 °C. As a result, for each lubricated powders, they were compared in terms of ability to give an acceptable dry pre-mixed powder for tableting process. The hardness of the compressed tablets is acceptable whatever the formulations tested. After in vitro release study, it could confirm that the different formulations of CR-CS tablet have a various release rate patterns, which could release 100% at 3 hrs, 6 hrs and 12 hrs. The in vitro dissolution profiles were in good correlation of Higuchi release kinetic model. In conclusion, this study could be used as a background for development and evaluation of the controlled-release carbon source (CR-CS) tablet for the purification of groundwater following the in situ denitrification.

  7. Linear alkanesulfonates as carbon and energy sources for gram-positive and gram-negative bacteria.

    PubMed

    Reichenbecher, W; Murrell, J C

    1999-01-01

    Several bacteria from soil and rainwater samples were enriched and isolated with propanesulfonate or butanesulfonate as sole carbon and energy source. Most of the strains isolated utilized nonsubstituted alkanesulfonates with a chain length of C3-C6 and the substituted sulfonates taurine and isethionate as carbon and energy source. A gram-positive isolate, P40, and a gram-negative isolate, P53, were characterized in more detail. Phylogenetic analysis grouped strain P40 within group IV of the genus Rhodococcus and showed a close relationship with Rhodococcus opacus. After phylogenetic and physiological analyses, strain P53 was identified as Comamonas acidovorans. Both bacteria also utilized a wide range of sulfonates as sulfur source. Strain P40, but not strain P53, released sulfite into the medium during dissimilation of sulfonated compounds. Cell-free extracts of strain P53 exhibited high sulfite oxidase activity [2.34 U (mg protein)-1] when assayed with ferricyanide, but not with cytochrome c. Experiments with whole-cell suspensions of both strains showed that the ability to dissimilate 1-propanesulfonate was specifically induced during growth on this substrate and was not present in cells grown on propanol, isethionate or taurine. Whole-cell suspensions of both strains accumulated acetone when oxidizing the non-growth substrate 2-propanesulfonate. Strain P40 cells also accumulated sulfite under these conditions. Stoichiometric measurements with 2-propanesulfonate as substrate in oxygen electrode experiments indicate that the nonsubstituted alkanesulfonates were degraded by a monooxygenase. When strain P53 grew with nonsubstituted alkanesulfonates as carbon and energy source, cells expressed high amounts of yellow pigments, supporting the proposition that an oxygenase containing iron sulfur centres or flavins was involved in their degradation.

  8. Source apportionment of carbonaceous aerosols over South and East Asia using dual carbon isotopes

    NASA Astrophysics Data System (ADS)

    Gustafsson, O.; Kirillova, E. N.; Andersson, A.-; Kruså, M.; Sheesley, R. J.; Tiwari, S.-; Lee, M.; Chen, B.; Du, K.

    2012-12-01

    Emissions of black carbon (BC) and other components of carbonaceous aerosols affect both climate and health in South and East Asia, yet substantial uncertainties exist regarding their sources. The relative contribution to atmospheric BC from fossil fuel versus biomass combustion is important to constrain both to direct mitigation and as their different properties make their effects on climate forcing and respiratory health different. This study approached the sourcing challenge by applying microscale radiocarbon measurements to aerosol particles collected in both source regions and at regional receptor observatories of both S Asia (New Delhi and the Maldives Climate Observatory) and of E Asia (Beijing, Shanghai, South China Coastal Observatory and the Korea Climate Observatory - Gosan, KCO-G, Jeju Island). The radiocarbon approach is ideally suited to this task as fossil sources are void of 14C whereas biomass combustion products hold a contemporary 14C signal. For S Asia, the 14C-based observations suggest that biomass combustion contributes half to two-thirds of the BC loading. In contrast, for E Asia, fossil fuel combustion account for four-fifths of the BC emitted from China. This source-diagnostic radiocarbon signal in the ambient aerosol over East Asia establishes a much larger role for fossil fuel combustion than suggested by all fifteen BC emission inventory models. There are also poor constraints on the sources of water-soluble organic carbon (WSOC), a large hydrophilic component of carbonaceous aerosols that enhances the propensity of aerosols to form clouds. In a 15-mo continuous campaign in S Asia, radiocarbon-based source apportionment of WSOC shows the dominance of biogenic/biomass combustion sources but also a substantial anthropogenic fossil-fuel contribution (about 20%). WSOC in E Asia reaching KCO-G were 50% from fossil sources. Aerosols reaching the Maldives after long-range over-ocean transport were enriched by 3-4‰ in δ13C-WSOC. This is

  9. Sources of black carbon to the Himalayan-Tibetan Plateau glaciers

    NASA Astrophysics Data System (ADS)

    Li, Chaoliu; Bosch, Carme; Kang, Shichang; Andersson, August; Chen, Pengfei; Zhang, Qianggong; Cong, Zhiyuan; Chen, Bing; Qin, Dahe; Gustafsson, Örjan

    2016-08-01

    Combustion-derived black carbon (BC) aerosols accelerate glacier melting in the Himalayas and in Tibet (the Third Pole (TP)), thereby limiting the sustainable freshwater supplies for billions of people. However, the sources of BC reaching the TP remain uncertain, hindering both process understanding and efficient mitigation. Here we present the source-diagnostic Δ14C/δ13C compositions of BC isolated from aerosol and snowpit samples in the TP. For the Himalayas, we found equal contributions from fossil fuel (46+/-11%) and biomass (54+/-11%) combustion, consistent with BC source fingerprints from the Indo-Gangetic Plain, whereas BC in the remote northern TP predominantly derives from fossil fuel combustion (66+/-16%), consistent with Chinese sources. The fossil fuel contributions to BC in the snowpits of the inner TP are lower (30+/-10%), implying contributions from internal Tibetan sources (for example, yak dung combustion). Constraints on BC sources facilitate improved modelling of climatic patterns, hydrological effects and provide guidance for effective mitigation actions.

  10. Sources of black carbon to the Himalayan–Tibetan Plateau glaciers

    PubMed Central

    Li, Chaoliu; Bosch, Carme; Kang, Shichang; Andersson, August; Chen, Pengfei; Zhang, Qianggong; Cong, Zhiyuan; Chen, Bing; Qin, Dahe; Gustafsson, Örjan

    2016-01-01

    Combustion-derived black carbon (BC) aerosols accelerate glacier melting in the Himalayas and in Tibet (the Third Pole (TP)), thereby limiting the sustainable freshwater supplies for billions of people. However, the sources of BC reaching the TP remain uncertain, hindering both process understanding and efficient mitigation. Here we present the source-diagnostic Δ14C/δ13C compositions of BC isolated from aerosol and snowpit samples in the TP. For the Himalayas, we found equal contributions from fossil fuel (46±11%) and biomass (54±11%) combustion, consistent with BC source fingerprints from the Indo-Gangetic Plain, whereas BC in the remote northern TP predominantly derives from fossil fuel combustion (66±16%), consistent with Chinese sources. The fossil fuel contributions to BC in the snowpits of the inner TP are lower (30±10%), implying contributions from internal Tibetan sources (for example, yak dung combustion). Constraints on BC sources facilitate improved modelling of climatic patterns, hydrological effects and provide guidance for effective mitigation actions. PMID:27552223

  11. Carbon sources for the Palaeozoic giant fungus Prototaxites inferred from modern analogues

    PubMed Central

    Hobbie, Erik A.; Boyce, C. Kevin

    2010-01-01

    A wide range of carbon isotope values in the Devonian fossil Prototaxites has been interpreted to support heterotrophy and the classification of Prototaxites as a giant fungus. This inference remains controversial because of the huge size of Prototaxites relative to co-occurring terrestrial vegetation and the lack of existing fungal analogues that display equally broad isotopic ranges. Here, we show wide isotopic variability in the modern saprotrophic fungus Arrhenia obscurata collected adjacent to shallow meltwater pools of a sparsely vegetated glacial succession in the Washington Cascades, USA. Soils collected specifically around the edges of these pools were up to 5‰ higher in δ13C than adjacent soils consistent with C3 origin. Microbial sources of primary production appear to cause these high δ13C values, and the environment may be analogous to that of the Early Devonian landscapes, where Prototaxites individuals with extreme isotopic variance were found. Carbon isotopes are also compared in Prototaxites, Devonian terrestrial vascular plants, and Devonian algal-derived lake sediments. Prototaxites isotopic values show little correspondence with those of contemporaneous tracheophytes, providing further evidence that non-vascular land plants or aquatic microbes were important contributors to its carbon sources. Thus, a saprotrophic fungal identity is supported for Prototaxites, which may have relied on deposits of algal-derived organic matter in floodplain environments that were less dominated by vascular plants than a straight reading of the macrofossil record might suggest. PMID:20335209

  12. Enhanced light absorption by mixed source black and brown carbon particles in UK winter

    SciTech Connect

    Liu, Shang; Aiken, Allison C.; Gorkowski, Kyle; Dubey, Manvendra K.; Cappa, Christopher D.; Williams, Leah R.; Herndon, Scott C.; Massoli, Paola; Fortner, Edward C.; Chhabra, Puneet S.; Brooks, William A.; Onasch, Timothy B.; Jayne, John T.; Worsnop, Douglas R.; China, Swarup; Sharma, Noopur; Mazzoleni, Claudio; Xu, Lu; Ng, Nga L.; Liu, Dantong; Allan, James D.; Lee, James D.; Fleming, Zoë L.; Mohr, Claudia; Zotter, Peter; Szidat, Sönke; Prévôt, André S. H.

    2015-09-30

    We report that black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC’s light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ~1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC’s warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. In conclusion, we find that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.

  13. Enhanced light absorption by mixed source black and brown carbon particles in UK winter

    DOE PAGES

    Liu, Shang; Aiken, Allison C.; Gorkowski, Kyle; ...

    2015-09-30

    We report that black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC’s light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ~1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC’s warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combinationmore » of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. In conclusion, we find that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models.« less

  14. Seasonal variability of organic matter composition in an Alaskan glacier outflow: insights into glacier carbon sources

    NASA Astrophysics Data System (ADS)

    Spencer, Robert G. M.; Vermilyea, Andrew; Fellman, Jason; Raymond, Peter; Stubbins, Aron; Scott, Durelle; Hood, Eran

    2014-05-01

    Glacier ecosystems are a significant source of bioavailable, yet ancient dissolved organic carbon (DOC). Characterizing DOC in Mendenhall Glacier outflow (southeast Alaska) we document a seasonal persistence to the radiocarbon-depleted signature of DOC, highlighting ancient DOC as a ubiquitous feature of glacier outflow. We observed no systematic depletion in Δ 14C-DOC with increasing discharge during the melt season that would suggest mobilization of an aged subglacial carbon store. However, DOC concentration, δ 13C-DOC, Δ 14C-DOC and fluorescence signatures appear to have been influenced by runoff from vegetated hillslopes above the glacier during onset and senescence of melt. In the peak glacier melt period, the Δ 14C-DOC of stream samples at the outflow (-181.7 to -355.3‰) was comparable to the Δ 14C-DOC for snow samples from the accumulation zone (-207.2 to -390.9‰), suggesting that ancient DOC from the glacier surface is exported in glacier runoff. The pre-aged DOC in glacier snow and runoff is consistent with contributions from fossil fuel combustion sources similar to those documented previously in ice cores and thus provides evidence for anthropogenic perturbation of the carbon cycle. Overall, our results emphasize the need to further characterize DOC inputs to glacier ecosystems, particularly in light of predicted changes in glacier mass and runoff in the coming century.

  15. High resolution carbon dioxide emission gridded data for China derived from point sources.

    PubMed

    Wang, Jinnan; Cai, Bofeng; Zhang, Lixiao; Cao, Dong; Liu, Lancui; Zhou, Ying; Zhang, Zhansheng; Xue, Wenbo

    2014-06-17

    A high spatial resolution carbon dioxide (CO2) emission map of China is proving to be essential for China's carbon cycle research and carbon reduction strategies given the current low quality of CO2 emission data and the inconsistencies in data quality between different regions. Ten km resolution CO2 emission gridded data has been built up for China based on point emission sources and other supporting data. The predominance of emissions from industrial point sources (84% of total emissions) in China supports the use of bottom-up methodology. The resultant emission map is informative and proved to be more spatially accurate than the EDGAR data. Spatial distribution of CO2 emissions in China is highly unbalanced and has positive spatial autocorrelation. The spatial pattern is mainly influenced by key cities and key regions, i.e., the Jing-Jin-Ji region, the Yangtze River delta region, and the Pearl River delta region. The emission map indicated that the supervision of 1% of total land could enable the management of about 70% of emissions in China.

  16. Culture strategies for lipid production using acetic acid as sole carbon source by Rhodosporidium toruloides.

    PubMed

    Huang, Xiang-Feng; Liu, Jia-Nan; Lu, Li-Jun; Peng, Kai-Ming; Yang, Gao-Xiang; Liu, Jia

    2016-04-01

    Rhodosporidium toruloides AS 2.1389 was tested using different concentrations of acetic acid as a low-cost carbon source for the production of microbial lipids, which are good raw materials for biodiesel production. It grew and had higher lipid contents in media containing 4-20 g/L acetic acid as the sole carbon source, compared with that in glucose-containing media under the same culture conditions. At acetic acid concentrations as high as 20 g/L and the optimal carbon-to-nitrogen ratio (C/N) of 200 in a batch culture, the highest biomass production was 4.35 g/L, with a lipid content of 48.2%. At acetic acid concentrations as low as 4 g/L, a sequencing batch culture (SBC) with a C/N of 100 increased biomass production to 4.21 g/L, with a lipid content of 38.6%. These results provide usable culture strategies for lipid production by R. toruloides AS 2.1389 when using diverse waste-derived volatile fatty acids.

  17. Global warming alters carbon sink and source situation of the Tibetan lakes

    NASA Astrophysics Data System (ADS)

    Jiang, H.; Ni, Q.; Yang, J.; Liu, W.

    2015-12-01

    Global warming would accelerate glacier retreat and permafrost degeneration on the Tibetan Plateau. The carbon stored in permafrost would be released to nearby lakes. However, little is known about how the carbon sink and source situation could be altered and what role the microbial community could play in Tibetan lakes in response to global warming. To fill this knowledge gap, six lakes (Erhai Lake, Qinghai Lake, Tuosu Lake, Gahai Lake, Xiaochaidan Lake and Lake Chaka) on the Tibetan Plateau were studied. In order to compare the seasonal variations in geochemistry and microbial communities, two sampling cruises were performed (May and July of 2015, corresponding to dry and wet seasons, respectively). For each lake, salinity, pH, dissolved organic carbon (DOC), total nitrogen (TN), and chlorophyll were measured for water samples, and salinity and total organic carbon (TOC) were measured for sediments. Chamber-based greenhouse gas flux measurement were performed on the surface of each lake. Microbial communities were analyzed by using MiSeq sequencing technique. The results showed that in response to seasonal variation (from dry to set season), lake surface increased by 5-20% (calculated on the basis of satellite data) and salinity decreased by 4-30% for the studied lakes, suggesting the studied lakes were diluted by precipitations. The DOC contents of the lake waters were almost stable for the studied lakes, whereas TN increased by more than 70% for the lakes with salinity less than 100g/L. In the meanwhile, chlorophyll content increased by more than 180% for lakes with low salinities (Erhai Lake, Qinghai Lake, and Tuosu Lake) and decreased by 17-94% for lakes with high salinities (Gahai Lake, Xiaoxhaidan Lake, and Lake Chaka. This indicated that desalination (precipitation plus glacier melt) would increase carbon fixation potential in Tibetan lakes. Microbial community analyses showed that microbial diversity increased in response to desalination. All in all

  18. Preliminary study on preparation of BCNO phosphor particles using citric acid as carbon source

    SciTech Connect

    Nuryadin, Bebeh W.; Pratiwi, Tripuspita; Faryuni, Irfana D.; Iskandar, Ferry Abdullah, Mikrajuddin; Khairurrijal; Ogi, Takashi; Okuyama, Kikuo

    2015-04-16

    A citric acid was used as a carbon source in the preparation of boron carbon oxy-nitride (BCNO) phosphor particles by a facile process. The preparation process was conducted at relatively low temperature 750 °C and at ambient pressure. The prepared BCNO phosphors showed a high photoluminescence (PL) performance at peak emission wavelength of 470 nm under excitation by a UV light 365 nm. The effects of carbon/boron and nitrogen/boron molar ratios on the PL properties were also investigated. The result showed that the emission spectra with a wavelength peak ranging from 444 nm to 496 nm can be obtained by varying carbon/boron ratios from 0.1 to 0.9. In addition, the observations showed that the BCNO phosphor material has two excitation peaks located at the 365 nm (UV) and 420 nm (blue). Based on these observations, we believe that the citric acid derived BCNO phosphor particles can be a promising inexpensive material for phosphor conversion-based white LED.

  19. Mineralization of Calcium Carbonate on Multifunctional Peptide Assembly Acting as Mineral Source Supplier and Template.

    PubMed

    Murai, Kazuki; Kinoshita, Takatoshi; Nagata, Kenji; Higuchi, Masahiro

    2016-09-13

    Crystal phase and morphology of biominerals may be precisely regulated by controlled nucleation and selective crystal growth through biomineralization on organic templates such as a protein. We herein propose new control factors of selective crystal growth by the biomineralization process. In this study, a designed β-sheet Ac-VHVEVS-CONH2 peptide was used as a multifunctional template that acted as mineral source supplier and having crystal phase control ability of calcium carbonate (CaCO3) during a self-supplied mineralization. The peptides formed three-dimensional nanofiber networks composed of assembled bilayer β-sheets. The assembly hydrolyzed urea molecules to one carbonate anion and two ammonium cations owing to a charge relay effect between His and Ser residues under mild conditions. CaCO3 was selectively mineralized on the peptide assembly using the generated carbonate anions on the template. Morphology of the obtained CaCO3 was fiber-like structure, similar to that of the peptide template. The mineralized CaCO3 on the peptide template had aragonite phase. This implies that CaCO3 nuclei, generated using the carbonate anions produced by the hydrolysis of urea on the surface of the peptide assembly, preferentially grew into aragonite phase, the growth axis of which aligned parallel to the direction of the β-sheet fiber axis.

  20. Preliminary study on preparation of BCNO phosphor particles using citric acid as carbon source

    NASA Astrophysics Data System (ADS)

    Nuryadin, Bebeh W.; Pratiwi, Tripuspita; Faryuni, Irfana D.; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal, Ogi, Takashi; Okuyama, Kikuo

    2015-04-01

    A citric acid was used as a carbon source in the preparation of boron carbon oxy-nitride (BCNO) phosphor particles by a facile process. The preparation process was conducted at relatively low temperature 750 °C and at ambient pressure. The prepared BCNO phosphors showed a high photoluminescence (PL) performance at peak emission wavelength of 470 nm under excitation by a UV light 365 nm. The effects of carbon/boron and nitrogen/boron molar ratios on the PL properties were also investigated. The result showed that the emission spectra with a wavelength peak ranging from 444 nm to 496 nm can be obtained by varying carbon/boron ratios from 0.1 to 0.9. In addition, the observations showed that the BCNO phosphor material has two excitation peaks located at the 365 nm (UV) and 420 nm (blue). Based on these observations, we believe that the citric acid derived BCNO phosphor particles can be a promising inexpensive material for phosphor conversion-based white LED.

  1. Contribution of various carbon sources toward isoprene synthesis mediated by altered atmospheric CO2 concentrations

    NASA Astrophysics Data System (ADS)

    Trowbridge, A. M.; Asensio, D.; Eller, A. S.; Wilkinson, M. J.; Schnitzler, J.; Jackson, R. B.; Monson, R. K.

    2010-12-01

    Biogenically released isoprene is abundant in the troposphere, and has an essential function in determining atmospheric chemistry and important implications for plant metabolism. As a result, considerable effort has been made to understand the underlying mechanisms driving isoprene synthesis, particularly in the context of a rapidly changing environment. Recently, a number of studies have focused on the contribution of recently assimilated carbon as opposed to stored/alternative intracellular or extracellular carbon sources in the context of environmental stress. Results from these studies can offer clues about the importance of various carbon pools for isoprene production and elucidate the corresponding physiological changes that are responsible for these dynamic shifts in carbon allocation. We performed a 13CO2-labeling study using proton-transfer-reaction mass spectrometry (PTR-MS) to examine the kinetics of the incorporation of recently assimilated photosynthate into isoprene emitted from poplar (Poplar x canescens) under sub-ambient, ambient, and elevated CO2 growth conditions. We also monitored the importance of pyruvate-derived carbon for isoprene biosynthesis and obtained a detailed account of where individual carbons are derived from by analyzing the ratio of the 3C subunit of isoprene (M41+) (a fragment which contains two carbons from pyruvate) to the ratio of the parent isoprene molecule (M69+). Dynamics in the M41+:M69+ ratio indicate that recently assimilated carbon is incorporated into the pyruvate carbon pool slowly across all CO2 treatments and is therefore accessible for isoprene synthesis at a slower rate when compared to substrates derived directly from photosynthesis. Analysis of the rates of change for individual masses indicated that the carbon pools in trees grown in sub-ambient CO2 (200 ppm) are labeled ~2 times faster than those of trees grown in ambient or elevated CO2. Analysis of the total isoprene emission rates between treatments

  2. Fine and ultrafine particulate organic carbon in the Los Angeles basin: Trends in sources and composition.

    PubMed

    Shirmohammadi, Farimah; Hasheminassab, Sina; Saffari, Arian; Schauer, James J; Delfino, Ralph J; Sioutas, Constantinos

    2016-01-15

    In this study, PM2.5 and PM0.18 (particles with dp<2.5 μm and dp<0.18 μm, respectively) were collected during 2012-2013 in Central Los Angeles (LA) and 2013-2014 in Anaheim. Samples were chemically analyzed for carbonaceous species (elemental and organic carbons) and individual organic compounds. Concentrations of organic compounds were reported and compared with many previous studies in Central LA to quantify the impact of emissions control measurements that have been implemented for vehicular emissions over the past decades in this area. Moreover, a novel hybrid approach of molecular marker-based chemical mass balance (MM-CMB) analysis was conducted, in which a combination of source profiles that were previously obtained from a Positive Matrix Factorization (PMF) model in Central LA, were combined with some traditional source profiles. The model estimated the relative contributions from mobile sources (including gasoline, diesel, and smoking vehicles), wood smoke, primary biogenic sources (including emissions from vegetative detritus, food cooking, and re-suspended soil dust), and anthropogenic secondary organic carbon (SOC). Mobile sources contributed to 0.65 ± 0.25 μg/m(3) and 0.32 ± 0.25 μg/m(3) of PM2.5 OC in Central LA and Anaheim, respectively. Primary biogenic and anthropogenic SOC sources were major contributors to OC concentrations in both size fractions and sites. Un-apportioned OC ("other OC") accounted for an average 8.0 and 26% of PM2.5 OC concentration in Central LA and Anaheim, respectively. A comparison with previous studies in Central LA revealed considerable reduction of EC and OC, along with tracers of mobile sources (e.g. PAHs, hopanes and steranes) as a result of implemented regulations on vehicular emissions. Given the significant reduction of the impacts of mobile sources in the past decade in the LA Basin, the impact of SOC and primary biogenic emissions have a larger relative impact and the new hybrid model allows the impact of

  3. Dynamic response of concrete beams externally reinforced with carbon fiber reinforced plastic (CFRP) subjected to impulsive loads

    SciTech Connect

    Jerome, D.M.; Ross, C.A.

    1996-12-31

    A series of 54 laboratory scale concrete beams 3 x 3 x 30 in. in size were impulsively loaded to failure in a drop weight impact machine. The beams had no internal reinforcement, but instead were externally reinforced on the bottom or tension side of the beams with 1, 2, and 3 ply AS4C/1919 graphite epoxy panels. In addition, several of the beams were also reinforced on the sides with 3 ply CFRP. The beams were simply supported in a drop weight machine and subjected to impact loads with amplitudes up to 10 kips, and durations less than 1 ms, at beam midspan. Measurements made during the loading event included beam total load, midspan displacement, as well as midspan strain at 3 locations in the beam`s cross-section. A high speed framing camera was also used to record the beam`s displacement-time behavior as well as to gain insight into the failure mechanisms. Beam midspan accelerations were determined by double differentiation of the displacement versus time data, and in turn, the beam`s inertial loads were calculated using the beam`s equivalent mass. Beam dynamic bending loads versus time were determined from the difference between the total load versus time and the inertial load versus time data. Bending loads versus displacements were also determined along with fracture energies. Failure to correct the loads for inertia will result in incorrect conclusions being drawn from the data, especially for bending resistance of brittle concrete test specimens. A comparison with quasistatic bending (fracture) energy data showed that the dynamic failure energy absorbed by the beams was always less than the static fracture energy, due to the brittle nature of concrete when impulsively loaded.

  4. Effects of nitrogen and carbon sources on the production of inulinase from strain Bacillus sp. SG113

    NASA Astrophysics Data System (ADS)

    Gavrailov, Simeon; Ivanova, Viara

    2016-03-01

    The effects of the carbon and nitrogen substrates on the growth of Bacillus sp. SG113 strain were studied. The use of organic nitrogen sources (peptone, beef extract, yeast extract, casein) leads to rapid cellular growth and the best results for the Bacillus strain were obtained with casein hydrolysate. From the inorganic nitrogen sources studied, the (NH4) 2SO4 proved to be the best nitrogen source. Casein hydrolysate and (NH4) 2SO4 stimulated the invertase synthesis. In the presence of Jerusalem artichoke, onion and garlic extracts as carbon sources the strain synthesized from 6 to 10 times more inulinase.

  5. Sink-source characteristics of two distinctly different forest species as affected by elevated carbon dioxide

    SciTech Connect

    Pushnik, J.C.; Florv, W.B.; Demaree, R.S. ); Anderson, P.D.; Houpis J.L.J. )

    1993-05-01

    The basic physiology and biochemistry of photosynthesis is being correlated with the leaf level processes and morphology of the Sierra Nevada varieties of Taxus brevifolia and Pinus ponderosa in an attempt to identify control mechanisms of carbohydrate partitioning. We are evaluating sink/source relationships in terms of carbon assimilation (gas-exchange (A[ci] curves and temperature effects); RuBPCase activity, chloroplast structure, integrity, and distributions, stomatal densities, internal leaf organization); transport functions (sucrose-phosphate synthetase (SPS) activity); long-term sink (immunoelectron microscopic detection of taxol). The results of these investigations suggest carbon acquisition characteristics are similar among the conifers, but with distinct differences in carboxylation efficiencies, SPS activity, needle starch content/chloroplast, and vascular tissue areas. These baseline characteristics are currently being evaluated in response to elevated CO[sub 2].

  6. Widely Tunable Single-Photon Source from a Carbon Nanotube in the Purcell Regime

    NASA Astrophysics Data System (ADS)

    Jeantet, A.; Chassagneux, Y.; Raynaud, C.; Roussignol, Ph.; Lauret, J. S.; Besga, B.; Estève, J.; Reichel, J.; Voisin, C.

    2016-06-01

    The narrow emission of a single carbon nanotube at low temperature is coupled to the optical mode of a fiber microcavity using the built-in spatial and spectral matching brought by this flexible geometry. A thorough cw and time-resolved investigation of the very same emitter both in free space and in cavity shows an efficient funneling of the emission into the cavity mode together with a strong emission enhancement corresponding to a Purcell factor of up to 5. At the same time, the emitted photons retain a strong sub-Poissonian statistics. By exploiting the cavity feeding effect on the phonon wings, we locked the emission of the nanotube at the cavity resonance frequency, which allowed us to tune the frequency over a 4 THz band while keeping an almost perfect antibunching. By choosing the nanotube diameter appropriately, this study paves the way to the development of carbon-based tunable single-photon sources in the telecom bands.

  7. Biomass burning sources of nitrogen oxides, carbon monoxide, and non-methane hydrocarbons

    SciTech Connect

    Atherton, C.S.

    1995-11-01

    Biomass burning is an important source of many key tropospheric species, including aerosols, carbon dioxide (CO{sub 2}), nitrogen oxides (NO{sub {times}}=NO+NO{sub 2}), carbon monoxide (CO), methane (CH{sub 4}), nitrous oxide (N{sub 2}O), methyl bromide (CH{sub 3}Br), ammonia (NH{sub 3}), non-methane hydrocarbons (NMHCs) and other species. These emissions and their subsequent products act as pollutants and affect greenhouse warming of the atmosphere. One important by-product of biomass burning is tropospheric ozone, which is a pollutant that also absorbs infrared radiation. Ozone is formed when CO, CH{sub 4}, and NMHCs react in the presence of NO{sub {times}} and sunlight. Ozone concentrations in tropical regions (where the bulk of biomass burning occurs) may increase due to biomass burning. Additionally, biomass burning can increase the concentration of nitric acid (HNO{sub 3}), a key component of acid rain.

  8. Atmospheric carbonyl sulfide sources from anthropogenic activity: Implications for carbon cycle constraints

    DOE PAGES

    Campbell, J. E.; Whelan, Mary; Seibt, U.; ...

    2015-04-16

    Carbonyl sulfide (COS) has recently emerged as an atmospheric tracer of gross primary production. All modeling studies of COS air-monitoring data rely on a climatological anthropogenic inventory that does not reflect present conditions or support interpretation of ice core and firn trends. Here we develop a global anthropogenic inventory for the years 1850 to 2013 based on new emission measurements and material-specific data. By applying methods from a recent regional inventory to global data, we find that the anthropogenic source is similar in magnitude to the plant sink, confounding carbon cycle applications. However, a material-specific approach results in a currentmore » anthropogenic source that is only one third of plant uptake and is concentrated in Asia, supporting carbon cycle applications of global air-monitoring data. As a result, changes in the anthropogenic source alone cannot explain the century-scale mixing ratio growth, which suggests that ice and firn data may provide the first global history of gross primary production.« less

  9. Atmospheric carbonyl sulfide sources from anthropogenic activity: Implications for carbon cycle constraints

    SciTech Connect

    Campbell, J. E.; Whelan, Mary; Seibt, U.; Smith, Steven J.; Berry, J. A.; Hilton, Timothy W.

    2015-04-16

    Carbonyl sulfide (COS) has recently emerged as an atmospheric tracer of gross primary production. All modeling studies of COS air-monitoring data rely on a climatological anthropogenic inventory that does not reflect present conditions or support interpretation of ice core and firn trends. Here we develop a global anthropogenic inventory for the years 1850 to 2013 based on new emission measurements and material-specific data. By applying methods from a recent regional inventory to global data, we find that the anthropogenic source is similar in magnitude to the plant sink, confounding carbon cycle applications. However, a material-specific approach results in a current anthropogenic source that is only one third of plant uptake and is concentrated in Asia, supporting carbon cycle applications of global air-monitoring data. As a result, changes in the anthropogenic source alone cannot explain the century-scale mixing ratio growth, which suggests that ice and firn data may provide the first global history of gross primary production.

  10. Metabolic engineering of Corynebacterium glutamicum aimed at alternative carbon sources and new products

    PubMed Central

    Zahoor, Ahmed; Lindner, Steffen N.; Wendisch, Volker F.

    2012-01-01

    Corynebacterium glutamicum is well known as the amino acid-producing workhorse of fermentation industry, being used for multi-million-ton scale production of glutamate and lysine for more than 60 years. However, it is only recently that extensive research has focused on engineering it beyond the scope of amino acids. Meanwhile, a variety of corynebacterial strains allows access to alternative carbon sources and/or allows production of a wide range of industrially relevant compounds. Some of these efforts set new standards in terms of titers and productivities achieved whereas others represent a proof-of-principle. These achievements manifest the position of C. glutamicum as an important industrial microorganism with capabilities far beyond the traditional amino acid production. In this review we focus on the state of the art of metabolic engineering of C. glutamicum for utilization of alternative carbon sources, (e.g. coming from wastes and unprocessed sources), and construction of C. glutamicum strains for production of new products such as diamines, organic acids and alcohols PMID:24688664

  11. Metabolic engineering of Corynebacterium glutamicum aimed at alternative carbon sources and new products.

    PubMed

    Zahoor, Ahmed; Lindner, Steffen N; Wendisch, Volker F

    2012-01-01

    Corynebacterium glutamicum is well known as the amino acid-producing workhorse of fermentation industry, being used for multi-million-ton scale production of glutamate and lysine for more than 60 years. However, it is only recently that extensive research has focused on engineering it beyond the scope of amino acids. Meanwhile, a variety of corynebacterial strains allows access to alternative carbon sources and/or allows production of a wide range of industrially relevant compounds. Some of these efforts set new standards in terms of titers and productivities achieved whereas others represent a proof-of-principle. These achievements manifest the position of C. glutamicum as an important industrial microorganism with capabilities far beyond the traditional amino acid production. In this review we focus on the state of the art of metabolic engineering of C. glutamicum for utilization of alternative carbon sources, (e.g. coming from wastes and unprocessed sources), and construction of C. glutamicum strains for production of new products such as diamines, organic acids and alcohols.

  12. BLACK Carbon Emissions from Diesel Sources in the Largest Arctic City: Case Study of Murmansk

    NASA Astrophysics Data System (ADS)

    Evans, M.; Kholod, N.; Malyshev, V.; Tretyakova, S.; Gusev, E.; Yu, S.; Barinov, A.

    2014-12-01

    Russia has very little data on its black carbon (BC) emissions. Because Russia makes up such a large share of the Arctic, understanding Russian emissions will improve our understanding of overall BC levels, BC in the Arctic and the link between BC and climate change. This paper provides a detailed, bottom-up inventory of BC emissions from diesel sources in Murmansk, Russia, along with uncertainty estimates associated with these emissions. The research team developed a detailed data collection methodology. The methodology involves assessing the vehicle fleet and activity in Murmansk using traffic, parking lot and driver surveys combined with an existing database from a vehicle inspection station and statistical data. The team also assessed the most appropriate emission factors, drawing from both Russian and international inventory methodologies. The researchers also compared fuel consumption using statistical data and bottom-up fuel calculations. They then calculated emissions for on-road transportation, off-road transportation (including mines), diesel generators, fishing and other sources. The article also provides a preliminary assessment of Russia-wide emissions of black carbon from diesel sources.

  13. Physico-chemical characterization and source tracking of black carbon at a suburban site in Beijing.

    PubMed

    Wang, Hailin; Nie, Lei; Liu, Dan; Gao, Meiping; Wang, Minyan; Hao, Zhengping

    2015-07-01

    Particles from ambient air and combustion sources including vehicle emission, coal combustion and biomass burning were collected and chemically pretreated with the purpose of obtaining isolated BC (black carbon) samples. TEM (transmission electron microscopy) results indicate that BC from combustion sources shows various patterns, and airborne BC appears spherical and about 50 nm in diameter with a homogeneous surface and turbostratic structure. The BET (Barrett-Emmett-Teller) results suggest that the surface areas of these BC particles fall in the range of 3-23 m2/g, with a total pore volume of 0.03-0.05 cm3/g and a mean pore diameter of 7-53 nm. The nitrogen adsorption-desorption isotherms are indicative of the accumulation mode and uniform pore size. O2-TPO (temperature programmed oxidation) profiles suggest that the airborne BC oxidation could be classified as the oxidation of amorphous carbon, which falls in the range of 406-490°C with peaks at 418, 423 and 475°C, respectively. Generally, the BC characteristics and source analysis suggest that airborne BC most likely comes from diesel vehicle emission at this site.

  14. Effect of carbon sources and shock loading on the removal of chlorophenols in sequential anaerobic-aerobic reactors.

    PubMed

    Majumder, Partha Sarathi; Gupta, S K

    2008-05-01

    The effect of carbon sources and shock loadings have been studied using two sets of sequential upflow anaerobic sludge blanket (UASB) and rotating biological contactor (RBC) reactors viz., UASB-I followed by RBC-I and UASB-II followed by RBC-II for the removal of two different priority pollutants, 2-CP and 2,4-DCP present in simulated wastewaters. Sodium formate, sodium propionate, glucose and methanol were used separately as four different carbon sources in the feed as co-substrate. Methanol was found to be the best carbon source for UASB reactors showing 95% 2-CP and 81.1% 2,4-DCP removals. The carbon sources formate and propionate were not found suitable in UASB reactors as only 22.6-46.8% 2-CP and 41.9-42.8% 2,4-DCP removals were observed. With glucose as carbon source 93.7% 2-CP and 79.6% 2,4-DCP removals were observed in UASB reactors. For all the four carbon sources more than 97.6% 2-CP and 99.7% 2,4-DCP removals were observed in sequential reactors. Although all the four carbon sources could not serve as good carbon source for UASB reactor alone but could be successfully used by the sequential reactors for the removal of chlorophenols. The Performance of sequential reactors was also evaluated at five different chlorophenolic shock loadings. During shock loading study the concentration of chlorophenols in the wastewaters was increased to 45, 60, 75, 90 and 105 mg/l as compared to the normal feed containing 30 mg/l 2-CP or 2,4-DCP. During shock loading study complete removal of 2-CP and more than 99.6% removal of 2,4-DCP was observed in sequential reactors. Sequential reactors successfully withstood all the shock loadings and produced high quality effluents.

  15. Organic sources and carbon sequestration in Holocene shelf sediments from the western Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Faux, Jessica F.; Belicka, Laura L.; Rodger Harvey, H.

    2011-08-01

    To quantify changes in organic carbon inputs and preservation, sediments from the Northern Chukchi Sea spanning the last 9000 years of the Holocene period were collected during the HOTRAX expedition and analyzed. The multi-proxy approach included molecular organic markers, bulk carbon and isotope measurements plus more recent approaches to terrestrial carbon estimation (the BIT index of Branched and Isoprenoid Tetraethers). The upper 1100 cm of the core, corresponding to the last 7.4 ka, showed a relatively stable total organic carbon content of 1.13-1.38% which decreased below 1100 cm to 0.6%. C:N ratios ranged from 8.4 to 10.83 over the Holocene time period examined. The distribution of n-alcohols and n-alkanes revealed major contributions from long-chain n-alcohols and n-alkanes while minimal contributions were seen from short-chain n-alkanes. The majority of the total fatty acids was comprised of saturated and monounsaturated fatty acids with short-chain and long-chain saturated fatty acids present in similar concentrations throughout most of the core and monounsaturated fatty acids decreasing down-core. Total sterol concentrations showed considerable inputs from marine sterols, C 28Δ 5,22, C 28Δ 5,24(28) and dinosterol, as well as C 29Δ 5, typically considered a terrestrial marker. The BIT indices for core sediments ranged from 0.021 to 0.216 with minor changes seen in older sequences. Overall, organic biomarkers indicate marine sources as the more dominant input of organic matter with lower but continual contributions from terrestrial sources at this location during the Holocene. The remarkable consistency among multiple molecular organic markers of both marine and terrestrial origin over the Holocene period encompassed by the core suggests that sinking material or surface sediments were heavily influenced by bottom currents or other mixing processes prior to their deposition.

  16. Carbon Dioxide Capture and Separation Techniques for Gasification-based Power Generation Point Sources

    SciTech Connect

    Pennline, H.W.; Luebke, D.R.; Jones, K.L.; Morsi, B.I.; Heintz, Y.J.; Ilconich, J.B.

    2007-06-01

    The capture/separation step for carbon dioxide (CO2) from large-point sources is a critical one with respect to the technical feasibility and cost of the overall carbon sequestration scenario. For large-point sources, such as those found in power generation, the carbon dioxide capture techniques being investigated by the in-house research area of the National Energy Technology Laboratory possess the potential for improved efficiency and reduced costs as compared to more conventional technologies. The investigated techniques can have wide applications, but the research has focused on capture/separation of carbon dioxide from flue gas (post-combustion from fossil fuel-fired combustors) and from fuel gas (precombustion, such as integrated gasification combined cycle or IGCC). With respect to fuel gas applications, novel concepts are being developed in wet scrubbing with physical absorption; chemical absorption with solid sorbents; and separation by membranes. In one concept, a wet scrubbing technique is being investigated that uses a physical solvent process to remove CO2 from fuel gas of an IGCC system at elevated temperature and pressure. The need to define an ideal solvent has led to the study of the solubility and mass transfer properties of various solvents. Pertaining to another separation technology, fabrication techniques and mechanistic studies for membranes separating CO2 from the fuel gas produced by coal gasification are also being performed. Membranes that consist of CO2-philic ionic liquids encapsulated into a polymeric substrate have been investigated for permeability and selectivity. Finally, dry, regenerable processes based on sorbents are additional techniques for CO2 capture from fuel gas. An overview of these novel techniques is presented along with a research progress status of technologies related to membranes and physical solvents.

  17. Carbon dioxide capture and separation techniques for advanced power generation point sources

    SciTech Connect

    Pennline, H.W.; Luebke, D.R.; Morsi, B.I.; Heintz, Y.J.; Jones, K.L.; Ilconich, J.B.

    2006-09-01

    The capture/separation step for carbon dioxide (CO2) from large-point sources is a critical one with respect to the technical feasibility and cost of the overall carbon sequestration scenario. For large-point sources, such as those found in power generation, the carbon dioxide capture techniques being investigated by the in-house research area of the National Energy Technology Laboratory possess the potential for improved efficiency and costs as compared to more conventional technologies. The investigated techniques can have wide applications, but the research has focused on capture/separation of carbon dioxide from flue gas (postcombustion from fossil fuel-fired combustors) and from fuel gas (precombustion, such as integrated gasification combined cycle – IGCC). With respect to fuel gas applications, novel concepts are being developed in wet scrubbing with physical absorption; chemical absorption with solid sorbents; and separation by membranes. In one concept, a wet scrubbing technique is being investigated that uses a physical solvent process to remove CO2 from fuel gas of an IGCC system at elevated temperature and pressure. The need to define an ideal solvent has led to the study of the solubility and mass transfer properties of various solvents. Fabrication techniques and mechanistic studies for hybrid membranes separating CO2 from the fuel gas produced by coal gasification are also being performed. Membranes that consist of CO2-philic silanes incorporated into an alumina support or ionic liquids encapsulated into a polymeric substrate have been investigated for permeability and selectivity. An overview of two novel techniques is presented along with a research progress status of each technology.

  18. In silico carbon molecular beam epitaxial growth of graphene on the h-BN substrate: carbon source effect on van der Waals epitaxy

    NASA Astrophysics Data System (ADS)

    Lee, Jonghoon; Varshney, Vikas; Park, Jeongho; Farmer, Barry L.; Roy, Ajit K.

    2016-05-01

    Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon molecular beam epitaxy (CMBE) techniques using solid carbon sublimation have reported relatively poor quality of the graphene. In this article, the CMBE growth of graphene on the h-BN substrate is numerically studied in order to identify the effect of the carbon source on the quality of the graphene film. The carbon molecular beam generated by the sublimation of solid carbon source materials such as graphite and glassy carbon is mostly composed of atomic carbon, carbon dimers and carbon trimers. Therefore, the graphene film growth becomes a complex process involving various deposition characteristics of a multitude of carbon entities. Based on the study of surface adsorption and film growth characteristics of these three major carbon entities comprising graphite vapour, we report that carbon trimers convey strong traits of vdW epitaxy prone to high quality graphene growth, while atomic carbon deposition is a surface-reaction limited process accompanied by strong chemisorption. The vdW epitaxial behaviour of carbon trimers is found to be substantial enough to nucleate and develop into graphene like planar films within a nanosecond of high flux growth simulation, while reactive atomic carbons tend to impair the structural integrity of the crystalline h-BN substrate upon deposition to form an amorphous interface between the substrate and the growing carbon film. The content of reactive atomic carbons in the molecular beam is suspected to be the primary cause of low quality graphene reported in the literature. A possible optimization of the molecular beam composition towards the synthesis of better quality graphene films is suggested.Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon

  19. Inorganic carbon acquisition by the hydrothermal vent tubeworm Riftia pachyptila depends upon high external PCO2 and upon proton-equivalent ion transport by the worm

    PubMed

    Goffredi; Childress; Desaulniers; Lee; Lallier; Hammond

    1997-01-01

    Riftia pachyptila is the most conspicuous organism living at deep sea hydrothermal vents along the East Pacific Rise. To support its large size and high growth rates, this invertebrate relies exclusively upon internal chemosynthetic bacterial symbionts. The animal must supply inorganic carbon at high rates to the bacteria, which are far removed from the external medium. We found substantial differences in body fluid total inorganic carbon (CO2) both within and between vent sites when comparing freshly captured worms from a variety of places. However, the primary influence on body fluid CO2 was the chemical characteristics of the site from which the worms were collected. Studies on tubeworms, both freshly captured and maintained in captivity, demonstrate that the acquisition of inorganic carbon is apparently limited by the availability of CO2, as opposed to bicarbonate, and thus appears to be accomplished via diffusion of CO2 into the plume, rather than by mediated transport of bicarbonate. The greatly elevated PCO2 measured at the vent sites (up to 12.6 kPa around the tubeworms), which is a result of low environmental pH (as low as 5.6 around the tubeworms), and elevated CO2 (as high as 7.1 mmol l-1 around the tubes) speeds this diffusion. Moreover, despite large and variable amounts of internal CO2, these worms maintain their extracellular fluid pH stable, and alkaline, in comparison with the environment. The maintenance of this alkaline pH acts to concentrate inorganic carbon into extracellular fluids. Exposure to N-ethylmaleimide, a non-specific H+-ATPase inhibitor, appeared to stop this process, resulting in a decline in extracellular pH and CO2. We hypothesize that the worms maintain their extracellular pH by active proton-equivalent ion transport via high concentrations of H+-ATPases. Thus, Riftia pachyptila is able to support its symbionts' large demand for inorganic carbon owing to the elevated PCO2 in the vent environment and because of its ability to

  20. Deciphering Microbial Carbon Sources in Petroleum Contaminated Sediments Using Compound Specific Radiocarbon Analysis

    NASA Astrophysics Data System (ADS)

    Morrill, P. L.; Szponar, N.; Maunder, C.; Marvin, C.; Slater, G. F.

    2008-12-01

    Microbial membrane phospholipid fatty acids (PLFAs) were analyzed to investigate microbial carbon sources and assess the impact of petroleum hydrocarbon contamination in one of North America's most contaminated harbours. Sediment cores were sampled from two locations in the harbour: a highly impacted area, Dofasco Boat Slip; and a less impacted area, Carole's Bay. Natural organic matter (NOM) and total petroleum hydrocarbons (TPHs) were two possible organic carbon sources for microbial metabolisms. While the majority of organic carbon (OC) at both Dofasco and Carole's Bay was NOM, petroleum hydrocarbons also contributed to the OC. As expected, the concentration of the TPHs was much greater at the Dofasco site (270 ug/g) compared to the TPHs concentration measured at Carole's Bay (50 ug/g). However, the % of PAHs that contributed to TPHs was very similar in the first three centimeters at both sites (9%). The PLFAs distributions at Carole's Bay and Dofasco were fairly similar indicating an overall bulk similarity between the communities notwithstanding higher contaminant concentrations at the Dofasco site. PLFA distributions changed with depth, consistent with changes in redox conditions from oxic to anoxia. The PLFAs extracted from the upper 3 cm of sediment from Carole's Bay had modern cap delta 14C values (with an average value of -66 ) compared to both the NOM (cap delta 14C -132 ) and TPH (cap delta 14C -775 ), suggesting that the carbon substrate for microbial metabolisms was a younger more labile source. The cap delta 14C isotopic values between individual PLFAs were indistinguishable (within the standard error of 20 for accuracy and reproducibility) demonstrating that if TPHs were degraded the impact on the cap delta 14C was not resolvable at Carole's Bay. Co-metabolic degradation of petroleum hydrocarbons is one possible degradation mechanism whereby biodegradation is occurring, but the contaminant carbon may not be incorporated into the microbial membrane

  1. Stable carbon isotope ratios in atmospheric methane and some of its sources

    NASA Technical Reports Server (NTRS)

    Tyler, Stanley C.

    1986-01-01

    Ratios of C-13/C-12 have been measured in atmospheric methane and in methane collected from sites and biota that represent potentially large sources of atmospheric methane. These include temperate marshes (about -48 percent to about -54 percent), landfills (about -51 percent to about -55 percent), and the first reported values for any species of termite (-72.8 + or - 3.1 percent for Reticulitermes tibialis and -57.3 + or - 1.6 percent for Zootermopsis angusticollis). Numbers in parentheses are delta C-13 values with respect to PDB (Peedee belemnite) carbonate. Most methane sources reported thus far are depleted in C-13 with respect to atmospheric methane (-47.0 + or - 0.3 percent). Individual sources of methane should have C-13/C-12 ratios characteristic of mechanisms of CH4 formation and consumption prior to release to the atmosphere. The mass-weighted average isotopic composition of all sources should equal the mean C-13 of atmospheric methane, corrected for a kinetic isotope effect in the OH attack of CH4. Assuming the kinetic isotope effect to be small (about -3.0 percent correction to -47.0), as in the literature, the new values given here for termite methane do not help to explain the apparent discrepancy between C-13/C-12 ratios of the known CH4 sources and that of atmospheric CH4.

  2. Influence of calcium sources on microbially induced calcium carbonate precipitation by Bacillus sp. CR2.

    PubMed

    Achal, Varenyam; Pan, Xiangliang

    2014-05-01

    Stimulation of microbially induced calcium carbonate precipitation (MICCP) is likely to be influenced by calcium sources. In order to study such influences, we performed MICCP using Bacillus sp. CR2 in nutrient broth containing urea, supplemented with different calcium sources (calcium chloride, calcium oxide, calcium acetate and calcium nitrate). The experiment lasted 7 days, during which bacterial growth, urease activity, calcite production and pH were measured. Our results showed that calcium chloride is the better calcium source for MICCP process, since it provides higher urease activity and more calcite production. The influences of calcium sources on MICCP were further studied using Fourier transform-infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. These analyses confirmed that the precipitate formed was CaCO3 and composed of predominantly calcite crystals with a little amount of aragonite and vaterite crystals. The maximum yield of calcite precipitation was achievable with calcium chloride followed by calcium nitrate as a calcium source. The results of present study may be applicable to media preparation during efficient MICCP process.

  3. Radiocarbon-Based Source apportionment of Elemental Carbon Aerosols at Seoul, South Korea

    NASA Astrophysics Data System (ADS)

    Shakerian Ghahferrokhi, Farid; Ahn, Jinho; Czimczik, Claudia I.; Holden, Sandra; Park, JinSoo

    2016-04-01

    In this study, 10 samples of PM2.5 (aerosol particle with diameter less than 2.5 μm) were collected in the Northeast of Seoul (37.60o N, 127.05o E), South Korea, over 2-4 day periods in May and June of 2015 with a high volume air sampler. The samples were analyzed for their bulk carbon (TC) and nitrogen (N) elemental and stable isotope composition with EA-IRMS. Elemental carbon (EC) was quantified with the Swiss_4S protocol using a Sunset OC/EC analyzer. Both, TC and EC were analyzed for their radiocarbon (14C) content via accelerator mass spectrometry. The mass and isotopic composition of organic carbon (OC) was quantified by (isotope) mass balance. TC loads were 6.6 +/- 1.5 ug C m-3 air (ave. +/- sd; range 4.7-9.7), with a ∆14C ranging from 240 to -446 per mill and a δ13C of -25.4+/-0.3 per mill. EC was a minor fraction of TC (7.2+/-1.9% or 0.5+/-0.2 ug C m-3 air). EC was strongly depleted in 14C (∆14C = -915 to -819 per mill), with fossil sources accounting for 88+/-3% of EC (6.3+/-1.7% of TC). OC was enriched in 14C above natural levels (∆14C = -401 to 309 per mill), and thus could not be partitioned into fossil and modern sources. Local wind directions showed that air masses originated from the South, demonstrating that regional sources may be the crucial contributor to PM pollution in Seoul during that sampling period (early summer).

  4. Compound specific radiocarbon analyses to apportion sources of combustion products in sedimentary pyrogenic carbon deposits

    NASA Astrophysics Data System (ADS)

    Hanke, Ulrich M.; Schmidt, Michael W. I.; McIntyre, Cameron P.; Reddy, Christopher M.; Wacker, Lukas; Eglinton, Timothy I.

    2016-04-01

    Pyrogenic carbon (PyC) is a collective term for carbon-rich residues comprised of a continuum of products generated during biomass burning and fossil fuel combustion. PyC is a key component of the global carbon cycle due to its slow intrinsic decomposition rate and its ubiquity in the environment. It can originate from natural or anthropogenic vegetation fires, coal mining, energy production, industry and transport. Subsequently, PyC can be transported over long distances by wind and water and can eventually be buried in sediments. Information about the origin of PyC (biomass burning vs. fossil fuel combustion) deposited in estuarine sediments is scarce. We studied the highly anoxic estuarine sediments of the Pettaquamscutt River (Rhode Island, U.S.) in high temporal resolution over 250 years and found different combustion proxies reflect local and regional sources of PyC (Hanke et al. in review; Lima et al. 2003). The polycyclic aromatic hydrocarbons (PAH) originate from long-range atmospheric transport, whereas bulk PyC, detected as benzene polycarboxylic acids (BPCA), mainly stems from local catchment run-off. However, to unambiguously apportion PyC sources, we need additional information, such as compound specific radiocarbon (14C) measurements. We report 14C data for individual BPCA including error analysis and for combustion-related PAH. First results indicate that biomass burning is the main source of PyC deposits, with additional minor contributions from fossil fuel combustion. References Hanke U.M., T.I. Eglinton, A.L.L. Braun, C. Reddy, D.B. Wiedemeier, M.W.I. Schmidt. Decoupled sedimentary records of combustion: causes and implications. In review. Lima, A. L.; Eglinton, T. I.; Reddy, C. M., High-resolution record of pyrogenic polycyclic aromatic hydrocarbon deposition during the 20th century. ES&T, 2003, 37 (1), 53-61.

  5. Influences of influent carbon source on extracellular polymeric substances (EPS) and physicochemical properties of activated sludge.

    PubMed

    Ye, Fenxia; Peng, Ge; Li, Ying

    2011-08-01

    It is necessary to understand the bioflocculation, settling and dewatering characteristics in the activated sludge process in order to establish more efficient operational strategies. The influences of carbon source on the extracellular polymeric substances (EPS) and flocculation, settling and dewatering properties of the activated sludge were investigated. Laboratory-scale completely mixed activated sludge processes were used to grow the activated sludge with different carbon sources of starch, glucose and sodium acetate. The sludge fed with acetate had highest loosely bound EPS (LB-EPS) and that fed with starch lowest. The amount of tightly bound EPS (TB-EPS), protein content in LB-EPS, polysaccharide content and protein contents in TB-EPS, were independent of the influent carbon source. The polysaccharide content in LB-EPS of the activated sludge fed with sodium acetate was lower slightly than those of starch and glucose. The sludge also had a nearly consistent flocs size and the sludge volume index (SVI) value. ESS content of the sludge fed with sodium acetate was higher initially, although it was similar to those fed with glucose and starch finally. However, the specific resistance to filtration and normalized capillary suction time fluctuated first, but finally were stable at around 5.0×10(8)mkg(-1) and 3.5 s Lg(-1) SS, respectively. Only the protein content in LB-EPS weakly correlated with the flocs size and SVI of the activated sludge. But there was no correlation between any other EPS contents or components and the physicochemical properties of the activated sludge.

  6. Differences in carbon source utilisation by orchid mycorrhizal fungi from common and endangered species of Caladenia (Orchidaceae).

    PubMed

    Mehra, S; Morrison, P D; Coates, F; Lawrie, A C

    2017-02-01

    Terrestrial orchids depend on orchid mycorrhizal fungi (OMF) as symbionts for their survival, growth and nutrition. The ability of OMF from endangered orchid species to compete for available resources with OMF from common species may affect the distribution, abundance and therefore conservation status of their orchid hosts. Eight symbiotically effective OMF from endangered and more common Caladenia species were tested for their ability to utilise complex insoluble and simple soluble carbon sources produced during litter degradation by growth with different carbon sources in liquid medium to measure the degree of OMF variation with host conservation status or taxonomy. On simple carbon sources, fungal growth was assessed by biomass. On insoluble substrates, ergosterol content was assessed using ultra-performance liquid chromatography (UPLC). The OMF grew on all natural materials and complex carbon sources, but produced the greatest biomass on xylan and starch and the least on bark and chitin. On simple carbon sources, the greatest OMF biomass was measured on most hexoses and disaccharides and the least on galactose and arabinose. Only some OMF used sucrose, the most common sugar in green plants, with possible implications for symbiosis. OMF from common orchids produced more ergosterol and biomass than those from endangered orchids in the Dilatata and Reticulata groups but not in the Patersonii and Finger orchids. This suggests that differences in carbon source utilisation may contribute to differences in the distribution of some orchids, if these differences are retained on site.

  7. Upscaling carbon fluxes over the Great Plains grasslands: Sinks and sources

    USGS Publications Warehouse

    Zhang, Li; Wylie, Bruce K.; Ji, Lei; Gilmanov, Tagir G.; Tieszen, Larry L.; Howar, Daniel M.

    2011-01-01

    Previous studies suggested that the grasslands may be carbon sinks or near equilibrium, and they often shift between carbon sources in drought years and carbon sinks in other years. It is important to understand the responses of net ecosystem production (NEP) to various climatic conditions across the U.S. Great Plains grasslands. Based on 15 grassland flux towers, we developed a piecewise regression model and mapped the grassland NEP at 250 m spatial resolution over the Great Plains from 2000 to 2008. The results showed that the Great Plains was a net sink with an averaged annual NEP of 24 ± 14 g C m−2 yr−1, ranging from a low value of 0.3 g C m−2 yr−1 in 2002 to a high value of 47.7 g C m−2 yr−1 in 2005. The regional averaged NEP for the entire Great Plains grasslands was estimated to be 336 Tg C yr−1 from 2000 to 2008. In the 9 year period including 4 dry years, the annual NEP was very variable in both space and time. It appeared that the carbon gains for the Great Plains were more sensitive to droughts in the west than the east. The droughts in 2000, 2002, 2006, and 2008 resulted in increased carbon losses over drought-affected areas, and the Great Plains grasslands turned into a relatively low sink with NEP values of 15.8, 0.3, 20.1, and 10.2 g C m−2 yr−1 for the 4 years, respectively.

  8. Growth of moderately halophilic bacteria isolated from sea water using phenol as the sole carbon source.

    PubMed

    Muñoz, J A; Pérez-Esteban, B; Esteban, M; de la Escalera, S; Gómez, M A; Martínez-Toledo, M V; González-López, J

    2001-01-01

    Moderately halophilic bacteria utilizing phenol as the sole carbon source were isolated by selective enrichment from sea water. The isolate (Gram-negative motile rods) was identified as Deleya venusta. It grew well in the presence of up to 1600 mg/L of phenol and 8% NaCl under aerobic conditions. When the cells were treated with chloramphenicol prior to the addition of phenol they did not utilize added phenol, even after prolonged incubation. Thus, the enzymes necessary for phenol metabolism appeared to be inducible.

  9. Classification of acoustic emission sources produced by carbon/epoxy composite based on support vector machine

    NASA Astrophysics Data System (ADS)

    Ding, Peng; Li, Qin; Huang, Xunlei

    2015-07-01

    Carbon/epoxy specimens were made and stretched to fracture. In the process, acoustic emission (AE) signals were collected and their parameters were set as the input parameters of the neural network. Results show that using support vector machine (SVM) network can recognize the difference of AE sources more accurately than using the BP neural network. In addition, the accuracy of the SVM increases when the number of the training set increases. It is proved that using AE signal parameters and SVM network can recognize the AE sources’ pattern well.

  10. Dynamic Balancing of Isoprene Carbon Sources Reflects Photosynthetic and Photorespiratory Responses to Temperature Stress1[W][OPEN

    PubMed Central

    Chambers, Jeffrey; Alves, Eliane G.; Teixeira, Andrea; Garcia, Sabrina; Holm, Jennifer; Higuchi, Niro; Manzi, Antonio; Abrell, Leif; Fuentes, Jose D.; Nielsen, Lars K.; Torn, Margaret S.; Vickers, Claudia E.

    2014-01-01

    The volatile gas isoprene is emitted in teragrams per annum quantities from the terrestrial biosphere and exerts a large effect on atmospheric chemistry. Isoprene is made primarily from recently fixed photosynthate; however, alternate carbon sources play an important role, particularly when photosynthate is limiting. We examined the relative contribution of these alternate carbon sources under changes in light and temperature, the two environmental conditions that have the strongest influence over isoprene emission. Using a novel real-time analytical approach that allowed us to examine dynamic changes in carbon sources, we observed that relative contributions do not change as a function of light intensity. We found that the classical uncoupling of isoprene emission from net photosynthesis at elevated leaf temperatures is associated with an increased contribution of alternate carbon. We also observed a rapid compensatory response where alternate carbon sources compensated for transient decreases in recently fixed carbon during thermal ramping, thereby maintaining overall increases in isoprene production rates at high temperatures. Photorespiration is known to contribute to the decline in net photosynthesis at high leaf temperatures. A reduction in the temperature at which the contribution of alternate carbon sources increased was observed under photorespiratory conditions, while photosynthetic conditions increased this temperature. Feeding [2-13C]glycine (a photorespiratory intermediate) stimulated emissions of [13C1–5]isoprene and 13CO2, supporting the possibility that photorespiration can provide an alternate source of carbon for isoprene synthesis. Our observations have important implications for establishing improved mechanistic predictions of isoprene emissions and primary carbon metabolism, particularly under the predicted increases in future global temperatures. PMID:25318937

  11. Degraded peatlands as a source of riverine organic carbon and enhanced river outgassing in Sumatra, Indonesia

    NASA Astrophysics Data System (ADS)

    Wit, Francisca; Rixen, Tim

    2014-05-01

    Sumatra, Indonesia, is well known for its widespread tropical peat lands. However, silvi- and agricultural purposes are currently inducing large-scale degradation of peat lands, transforming the landscape into mainly palm-oil plantations. The degradation induces loss of carbon via direct CO2 emissions, but also via riverine outflow of dissolved and particulate organic carbon (DOC and POC, respectively) due to leaching. This organic carbon is then decomposed along the way towards the coast and is hypothesized to enhance coastal and river outgassing of CO2. In the framework of SPICE III, Science for the Protection of Indonesian Coastal Ecosystems, we are quantifying these carbon budgets and fluxes in the rivers and coastal areas of northeast Sumatra. Using underway instruments, we have gathered continuous measurements of various parameters, including pCO2, pH, temperature, salinity and oxygen. In addition, water samples were obtained for DOC, POC, δ13CDIC, alkalinity and nutrient analyses. The results of the first analyses show that pCO2 values in the coastal areas range between 400-600 μatm. However, in the vicinity of the rivers pCO2 concentrations increase tremendously, ranging from 600 near the estuaries to a staggering 9000 μatm further upstream. These values are much higher than the marine pCO2 value of 390 μatm in the South China Sea. When adding carbon isotope results into the story, while knowing that upstream river life is greatly reduced due to oxygen depletion as a result of high DOC decomposition, it appears to be clear from the values, which range between -20 to -24‰ δ13CDIC, that the main source of the organic carbon is indeed originating from the degrading peat lands. In conclusion, our hypothesis can be deemed correct: degrading peat lands enhance organic carbon outflow and therefore elevated decomposition in the rivers, which results in increased river outgassing of CO2. Further analyses will be conducted to precisely quantify the budgets and

  12. Molecular single source precursors for synthesis of nitrogen-rich carbon nitride materials

    NASA Astrophysics Data System (ADS)

    Miller, Dale R.

    This dissertation describes work on the synthesis, characterization and application of nitrogen-rich (CN1.0-1.6), graphite-like, carbon nitride (CNX) materials. Despite the focus of many recent efforts towards diamond-like carbon nitrides, graphite-like carbon nitrides are able to stand alone as interesting and challenging materials. The CNX powders and films studied here were synthesized using a single-source precursor approach. Focus was aimed at precursors containing an s-triazine (C3N3) aromatic ring with a variety of substituents, including -NHCl, -N3, pyridyl, hydrazino and alkyl amino. In contrast to past high temperature/high pressure studies, this work focused on precursors designed to decompose at low temperature (< 400 °C) and ambient pressure. Precursors containing reactive substituents (-N3, -NHNH 2, -NHCl) are particularly good for low temperature (< 300 °C) production of nitrogen-rich CNX powders and films, some of which exhibit blue photoluminescence. Specifically, the commercial molecule trichloromelamine, [TCM, C3N3(NHCl)3], was shown to decompose rapidly and energetically near 185 °C, using thermal methods to produce CN1.6H0.7 powders. Capitalizing on the electron rich nitrogen sites of the TCM derived CNX material, both hot filament decomposition and hydrogen reduction were used to incorporate transition metals. The hydrogen reduction method was used to examine a series of CNX/metal (Pt, Cu, Ni) samples for use as methanol fuel cell catalyst supports. Carbon paste electrodes made from CNX/Pt and CNX/Ni materials showed promising catalytic behavior. The success of the s-triazine precursor approach was successfully extended to the larger ring system, s-heptazine. Specifically, 2,5,8-triazido-s-heptazine, [TAH, C6N 7(N3)3], was shown to be even more successful than its smaller counterpart 2,4,6-triazido-s-triazine, [TAT, C3N3(N3)3), at producing nitrogen-rich carbon nitride powders. The structurally ambiguous CNX materials were characterized

  13. Silicon nanowire and carbon nanotube hybrid for room temperature multiwavelength light source

    PubMed Central

    Lo Faro, Maria Josè; D’Andrea, Cristiano; Messina, Elena; Fazio, Barbara; Musumeci, Paolo; Reitano, Riccardo; Franzò, Giorgia; Gucciardi, Pietro Giuseppe; Vasi, Cirino; Priolo, Francesco; Iacona, Fabio; Irrera, Alessia

    2015-01-01

    The realization of an innovative hybrid light source operating at room temperature, obtained by embedding a carbon nanotube (CNT) dispersion inside a Si nanowire (NW) array is reported. The NW/CNT system exhibits a peculiar photoluminescence spectrum, consisting of a wide peak, mainly observed in the visible range, due to quantum confined Si NWs, and of several narrower IR peaks, due to the different CNT chiralities present in the dispersion. The detailed study of the optical properties of the hybrid system evidences that the ratio between the intensity of the visible and the IR emissions can be varied within a wide range by changing the excitation wavelength or the CNT concentration; the conditions leading to the prevalence of one signal with respect to the other are identified. The multiplicity of emission spectra obtainable from this composite material opens new perspectives for Si nanostructures as active medium in light sources for Si photonics applications. PMID:26592198

  14. Production of a bioflocculant from Aspergillus niger using palm oil mill effluent as carbon source.

    PubMed

    Aljuboori, Ahmad H Rajab; Uemura, Yoshimitsu; Osman, Noridah Binti; Yusup, Suzana

    2014-11-01

    This study evaluated the potential of bioflocculant production from Aspergillus niger using palm oil mill effluent (POME) as carbon source. The bioflocculant named PM-5 produced by A. niger showed a good flocculating capability and flocculating rate of 76.8% to kaolin suspension could be achieved at 60 h of culture time. Glutamic acid was the most favorable nitrogen source for A. niger in bioflocculant production at pH 6 and temperature 35 °C. The chemical composition of purified PM-5 was mainly carbohydrate and protein with 66.8% and 31.4%, respectively. Results showed the novel bioflocculant (PM-5) had high potential to treat river water from colloids and 63% of turbidity removal with the present of Ca(2+) ion.

  15. Influence of setup and carbon source on the bacterial community of biocathodes in microbial electrolysis cells.

    PubMed

    Croese, Elsemiek; Jeremiasse, Adriaan W; Marshall, Ian P G; Spormann, Alfred M; Euverink, Gert-Jan W; Geelhoed, Jeanine S; Stams, Alfons J M; Plugge, Caroline M

    2014-01-01

    The microbial electrolysis cell (MEC) biocathode has shown great potential as alternative for expensive metals as catalyst for H2 synthesis. Here, the bacterial communities at the biocathode of five hydrogen producing MECs using molecular techniques were characterized. The setups differed in design (large versus small) including electrode material and flow path and in carbon source provided at the cathode (bicarbonate or acetate). A hydrogenase gene-based DNA microarray (Hydrogenase Chip) was used to analyze hydrogenase genes present in the three large setups. The small setups showed dominant groups of Firmicutes and two of the large setups showed dominant groups of Proteobacteria and Bacteroidetes. The third large setup received acetate but no sulfate (no sulfur source). In this setup an almost pure culture of a Promicromonospora sp. developed. Most of the hydrogenase genes detected were coding for bidirectional Hox-type hydrogenases, which have shown to be involved in cytoplasmatic H2 production.

  16. An audit of the global carbon budget: identifying and reducing sources of uncertainty

    NASA Astrophysics Data System (ADS)

    Ballantyne, A. P.; Tans, P. P.; Marland, G.; Stocker, B. D.

    2012-12-01

    Uncertainties in our carbon accounting practices may limit our ability to objectively verify emission reductions on regional scales. Furthermore uncertainties in the global C budget must be reduced to benchmark Earth System Models that incorporate carbon-climate interactions. Here we present an audit of the global C budget where we try to identify sources of uncertainty for major terms in the global C budget. The atmospheric growth rate of CO2 has increased significantly over the last 50 years, while the uncertainty in calculating the global atmospheric growth rate has been reduced from 0.4 ppm/yr to 0.2 ppm/yr (95% confidence). Although we have greatly reduced global CO2 growth rate uncertainties, there remain regions, such as the Southern Hemisphere, Tropics and Arctic, where changes in regional sources/sinks will remain difficult to detect without additional observations. Increases in fossil fuel (FF) emissions are the primary factor driving the increase in global CO2 growth rate; however, our confidence in FF emission estimates has actually gone down. Based on a comparison of multiple estimates, FF emissions have increased from 2.45 ± 0.12 PgC/yr in 1959 to 9.40 ± 0.66 PgC/yr in 2010. Major sources of increasing FF emission uncertainty are increased emissions from emerging economies, such as China and India, as well as subtle differences in accounting practices. Lastly, we evaluate emission estimates from Land Use Change (LUC). Although relative errors in emission estimates from LUC are quite high (2 sigma ~ 50%), LUC emissions have remained fairly constant in recent decades. We evaluate the three commonly used approaches to estimating LUC emissions- Bookkeeping, Satellite Imagery, and Model Simulations- to identify their main sources of error and their ability to detect net emissions from LUC.; Uncertainties in Fossil Fuel Emissions over the last 50 years.

  17. Mixed carbon sources for nitrate reduction in activated sludge-identification of bacteria and process activity studies.

    PubMed

    Hagman, M; Nielsen, J L; Nielsen, P H; Jansen, J la C

    2008-03-01

    Mixtures of methanol and acetate as carbon source were investigated in order to determine their capacity to enhance denitrification and for analysis of the microbial composition and carbon degradation activity in activated sludge from wastewater treatment plants. Laboratory batch reactors at 20 degrees C were used for nitrate uptake rate (NUR) measurements in order to investigate the anoxic activity, while single and mixed carbon substrates were added to activated sludge. Microautoradiography (MAR) in combination with fluorescence in situ hybridisation (FISH) were applied for microbial analysis during exposure to different carbon sources. The NUR increased with additions of a mixture of acetate and methanol compared with additions of a single carbon source. MAR-FISH measurements demonstrated that the probe-defined group of Azoarcus was the main group of bacteria utilising acetate and the only active group utilising methanol under anoxic conditions. The present study indicated an improved denitrification potential by additions of a mixed carbon source compared with commonly used single-carbon additions. It is also established that Azoarcus bacteria are involved in the degradation of both acetate and methanol in the anoxic activated sludge.

  18. Effect of carbon source on acclimatization of nitrifying bacteria to achieve high-rate partial nitrification of wastewater with high ammonium concentration

    NASA Astrophysics Data System (ADS)

    Mousavi, Seyyed Alireza; Ibrahim, Shaliza; Aroua, Mohamed Kheireddine

    2014-08-01

    Experiments in two laboratory-scale sequential batch reactors were carried out to investigate the effect of heterotrophic bacteria on nitrifying bacteria using external carbon sources. Partial nitrification of ammonium-rich wastewater during short-term acclimatization enriched the activity of ammonia-oxidizing bacteria in both reactors. Heterotrophic bacteria exhibited a minor effect on nitrifying bacteria, and complete removal of ammonium occurred at a rate of 41 mg L-1 h-1 in both reactors. The main strategy of this research was to carry out partial nitrification using high-activity ammonia-oxidizing bacteria with a high concentration of free ammonia (70 mg L-1). The NO2 -/(NO3 - + NO2 -) ratio was greater than 0.9 in both reactors most of the time.

  19. Stationary chest tomosynthesis using a carbon nanotube x-ray source array: a feasibility study

    NASA Astrophysics Data System (ADS)

    Shan, Jing; Tucker, Andrew W.; Lee, Yueh Z.; Heath, Michael D.; Wang, Xiaohui; Foos, David H.; Lu, Jianping; Zhou, Otto

    2015-01-01

    Chest tomosynthesis is a low-dose, quasi-3D imaging modality that has been demonstrated to improve the detection sensitivity for small lung nodules, compared to 2D chest radiography. The purpose of this study is to investigate the feasibility and system requirements of stationary chest tomosynthesis (s-DCT) using a spatially distributed carbon nanotube (CNT) x-ray source array, where the projection images are collected by electronically activating individual x-ray focal spots in the source array without mechanical motion of the x-ray source, detector, or the patient. A bench-top system was constructed using an existing CNT field emission source array and a flat panel detector. The tube output, beam quality, focal spot size, system in-plane and in-depth resolution were characterized. Tomosynthesis slices of an anthropomorphic chest phantom were reconstructed for image quality assessment. All 75 CNT sources in the source array were shown to operate reliably at 80 kVp and 5 mA tube current. Source-to-source consistency in the tube current and focal spot size was observed. The incident air kerma reading per mAs was measured as 74.47 uGy mAs-1 at 100 cm. The first half value layer of the beam was 3 mm aluminum. An average focal spot size of 2.5  ×  0.5 mm was measured. The system MTF was measured to be 1.7 cycles mm-1 along the scanning direction, and 3.4 cycles mm-1 perpendicular to the scanning direction. As the angular coverage of 11.6°-34°, the full width at half maximum of the artifact spread function improved greatly from 9.5 to 5.2 mm. The reconstructed tomosynthesis slices clearly show airways and pulmonary vascular structures in the anthropomorphic lung phantom. The results show the CNT source array is capable of generating sufficient dose for chest tomosynthesis imaging. The results obtained so far suggest an s-DCT using a distributed CNT x-ray source array is feasible.

  20. Development of a stationary chest tomosynthesis system using carbon nanotube x-ray source array

    NASA Astrophysics Data System (ADS)

    Shan, Jing

    X-ray imaging system has shown its usefulness for providing quick and easy access of imaging in both clinic settings and emergency situations. It greatly improves the workflow in hospitals. However, the conventional radiography systems, lacks 3D information in the images. The tissue overlapping issue in the 2D projection image result in low sensitivity and specificity. Both computed tomography and digital tomosynthesis, the two conventional 3D imaging modalities, requires a complex gantry to mechanically translate the x-ray source to various positions. Over the past decade, our research group has developed a carbon nanotube (CNT) based x-ray source technology. The CNT x-ray sources allows compacting multiple x-ray sources into a single x-ray tube. Each individual x-ray source in the source array can be electronically switched. This technology allows development of stationary tomographic imaging modalities without any complex mechanical gantries. The goal of this work is to develop a stationary digital chest tomosynthesis (s-DCT) system, and implement it for a clinical trial. The feasibility of s-DCT was investigated. It is found that the CNT source array can provide sufficient x-ray output for chest imaging. Phantom images have shown comparable image qualities as conventional DCT. The s-DBT system was then used to study the effects of source array configurations and tomosynthesis image quality, and the feasibility of a physiological gated s-DCT. Using physical measures for spatial resolution, the 2D source configuration was shown to have improved depth resolution and comparable in-plane resolution. The prospective gated tomosynthesis images have shown substantially reduction of image blur associated with lung motions. The system was also used to investigate the feasibility of using s-DCT as a diagnosis and monitoring tools for cystic fibrosis patients. A new scatter reduction methods for s-DCT was also studied. Finally, a s-DCT system was constructed by

  1. Influence of carbon and lipid sources on variation of mercury and other trace elements in polar bears (Ursus maritimus).

    PubMed

    Routti, Heli; Letcher, Robert J; Born, Erik W; Branigan, Marsha; Dietz, Rune; Evans, Thomas J; McKinney, Melissa A; Peacock, Elizabeth; Sonne, Christian

    2012-12-01

    In the present study, the authors investigated the influence of carbon and lipid sources on regional differences in liver trace element (As, Cd, Cu, total Hg, Mn, Pb, Rb, Se, and Zn) concentrations measured in polar bears (Ursus maritimus) (n = 121) from 10 Alaskan, Canadian Arctic, and East Greenland subpopulations. Carbon and lipid sources were assessed using δ(13) C in muscle tissue and fatty acid (FA) profiles in subcutaneous adipose tissue as chemical tracers. A negative relationship between total Hg and δ(13) C suggested that polar bears feeding in areas with higher riverine inputs of terrestrial carbon accumulate more Hg than bears feeding in areas with lower freshwater input. Mercury concentrations were also positively related to the FA 20:1n-9, which is biosynthesized in large amounts in Calanus copepods. This result raises the hypothesis that Calanus glacialis are an important link in the uptake of Hg in the marine food web and ultimately in polar bears. Unadjusted total Hg, Se, and As concentrations showed greater geographical variation among polar bear subpopulations compared with concentrations adjusted for carbon and lipid sources. The Hg concentrations adjusted for carbon and lipid sources in Bering-Chukchi Sea polar bear liver tissue remained the lowest among subpopulations. Based on these findings, the authors suggest that carbon and lipid sources for polar bears should be taken into account when one is assessing spatial and temporal trends of long-range transported trace elements.

  2. Controlling single and few-layer graphene crystals growth in a solid carbon source based chemical vapor deposition

    SciTech Connect

    Papon, Remi; Sharma, Subash; Shinde, Sachin M.; Vishwakarma, Riteshkumar; Tanemura, Masaki; Kalita, Golap

    2014-09-29

    Here, we reveal the growth process of single and few-layer graphene crystals in the solid carbon source based chemical vapor deposition (CVD) technique. Nucleation and growth of graphene crystals on a polycrystalline Cu foil are significantly affected by the injection of carbon atoms with pyrolysis rate of the carbon source. We observe micron length ribbons like growth front as well as saturated growth edges of graphene crystals depending on growth conditions. Controlling the pyrolysis rate of carbon source, monolayer and few-layer crystals and corresponding continuous films are obtained. In a controlled process, we observed growth of large monolayer graphene crystals, which interconnect and merge together to form a continuous film. On the other hand, adlayer growth is observed with an increased pyrolysis rate, resulting few-layer graphene crystal structure and merged continuous film. The understanding of monolayer and few-layer crystals growth in the developed CVD process can be significant to grow graphene with controlled layer numbers.

  3. Adsorbent materials for carbon dioxide capture fro