Carbon deposition on 20/25/Nb steel using an electrically heated AGR fuel pin

International Nuclear Information System (INIS)

Blanchard, A.; Campion, P.

1980-01-01

The radiolysis of carbon dioxide in gas-cooled reactors leads to the production of active species capable of reacting with the graphite moderator to form carbon monoxide with a resultant gradual loss of moderator. In the early days of gas-cooled reactor design, the intention was to allow the carbon monoxide concentration to increase and use this reaction product to inhibit the initial radiolysis of the carbon dioxide. Exploratory irradiation experiments using 4 to 7% carbon monoxide revealed that low density deposits ranging in colour from light grey through brown to black were found in the temperature range 470 to 600 K. In view of the fact that this type of deposition could adversely affect heat transfer processes in both fuel channels and heat exchangers, together with the fact that carbon monoxide was not sufficiently powerful as a graphite oxidation inhibitor, methane was selected as the primary inhibitor for the AGR series of power stations. This paper describes some carbon deposition experiments using an electrically heated 'dummy fuel element' linked to a recirculating carbon dioxide irradiation loop in which carbon monoxide concentration, methane concentration, fuel pin temperature and the chemical nature of the fuel pin surface were varied. (author)

Pt20RuxSny nanoparticles dispersed on mesoporous carbon CMK-3 and their application in the oxidation of 2-carbon alcohols and fermentation effluent

International Nuclear Information System (INIS)

Lo, An-Ya; Chung, Yi-Chen; Hung, Wei-Hsuan; Hsu, Yun-Chi; Tseng, Chuan-Ming; Zhang, Wei-Lun; Wang, Fu-Kai; Lin, Chiu-Yue

2017-01-01

Highlights: • Pt 20 Ru x Sn y @C catalysts are formed by dispersing Pt-Sn and Pt-Ru-Sn NPs on CMK-3. • They are tested in fuel cells using ethanol, ethylene glycol, and CFHPE as fuels. • Higher Sn contents improve catalytic efficiency of Pt 20 Ru x Sn y when x = 0 or x = 10. • Role of Sn in C−C bond cleavage and improving poisoning tolerance is explained. • Pt 20 Ru 10 Sn 15 @C is used to show feasibility of using bioalcohol from CFHPE as fuel. - Abstract: We report the synthesis of Pt-Sn binary and Pt-Ru-Sn ternary alloy nanoparticles (NPs) dispersed on mesoporous carbon CMK-3 for bioalcohol fuel cell applications where ethanol, ethylene glycol, and fermentative hydrogen production effluent were used as the fuels. The proposed alloy electrocatalysts, denoted as Pt 20 Ru x Sn y @C (where 20, x, and y represent the weight fractions of Pt, Ru, and Sn, respectively), were examined using scanning electron microscopy, energy-dispersive X-ray spectroscopy mapping, transmission electron microscopy, Brunauer-Emmett-Teller measurements, X-ray diffraction analysis, and electrochemical measurements, in order to determine their morphologies, microstructures, compositions, phase structures, and electrochemical characteristics. The effects of the Sn content on the following factors were examined: 1) average particle size of the alloy NPs, 2) mesoporosity, 3) electrochemically active surfaces of Pt 20 Ru x Sn y @C, and 4) ethanol oxidation reaction and ethylene glycol oxidation reaction activities. Higher Sn contents improved the catalytic efficiency of Pt 20 Ru x Sn y when x = 0 or x = 10, with the optimized compositions being Pt 20 Sn 30 and Pt 20 Ru 10 Sn 15 for the binary and ternary alloys, respectively. Based on the ethanol and ethylene glycol oxidation reactions, we explain the role of Sn in promoting C−C bond cleavage and in improving catalyst tolerance against poisoning. Overall, for both the ethanol system and the ethylene glycol system, the catalytic

Synthesis of position-specific tritium-labeled 20(S)-camptothecin, 9-amino-20(S)-camptothecin, and 10,11-methylenedioxy-20(S)-camptothecin

International Nuclear Information System (INIS)

Nicholas, A.W.; Wani, M.C.; Wall, M.E.; Kepler, J.A.; Taylor, G.F.

1993-01-01

The synthesis is given for three ring A tritiated camptothecin (CPT) analogs as biological probes in the study of the parent compounds which are of current widespread interest as potent anticancer agents. The strategy of catalytic tritolysis of aryl halide bonds was employed, and thus the preparations of the requisite precursors 9-chloro-20(S)-CPT, 9-amino-10,12-dibromo-20(S)-CPT, and 9-chloro-10,11-methylenedioxy-20(S)-CPT are given; catalytic tritiation of these respective precursors under polar, alkaline solvent conditions using palladium/carbon provides smooth conversion to [9- 3 H]-20(S)-CPT, 9-amino-[1012 3 H]-20(S)-CPT, and [9- 3 H]-10,11-methylenedioxy-20(S)-CPT. (author)

Hydrogen Storage in Carbon Nano-materials

International Nuclear Information System (INIS)

David Eyler; Michel Junker; Emanuelle Breysse Carraboeuf; Laurent Allidieres; David Guichardot; Fabien Roy; Isabelle Verdier; Edward Mc Rae; Moulay Rachid Babaa; Gilles Flamant; David Luxembourg; Daniel Laplaze; Patrick Achard; Sandrine Berthon-Fabry; David Langohr; Laurent Fulcheri

2006-01-01

This paper presents the results of a French project related to hydrogen storage in carbon nano-materials. This 3 years project, co-funded by the ADEME (French Agency for the Environment and the Energy Management), aimed to assess the hydrogen storage capacity of carbon nano-materials. Four different carbon materials were synthesized and characterized in the frame of present project: - Carbon Nano-tubes; - Carbon Nano-fibres; - Carbon Aerogel; - Carbon Black. All materials tested in the frame of this project present a hydrogen uptake of less than 1 wt% (-20 C to 20 C). A state of the art of hydrogen storage systems has been done in order to determine the research trends and the maturity of the different technologies. The choice and design of hydrogen storage systems regarding fuel cell specifications has also been studied. (authors)

Vibrationally Excited Carbon Monoxide Produced via a Chemical Reaction Between Carbon Vapor and Oxygen

Science.gov (United States)

Jans, Elijah R.; Eckert, Zakari; Frederickson, Kraig; Rich, Bill; Adamovich, Igor V.

2017-06-01

Measurements of the vibrational distribution function of carbon monoxide produced via a reaction between carbon vapor and molecular oxygen has shown a total population inversion on vibrational levels 4-7. Carbon vapor, produced using an arc discharge to sublimate graphite, is mixed with an argon oxygen flow. The excited carbon monoxide is vibrationally populated up to level v=14, at low temperatures, T=400-450 K, in a collision-dominated environment, 15-20 Torr, with total population inversions between v=4-7. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of the reaction enthalpy. Kinetic modeling of the flow reactor, including state specific vibrational processes, was performed to infer the vibrational distribution of the products of the reaction. The results show viability of developing of a new chemical CO laser from the reaction of carbon vapor and oxygen.

Forests and carbon storage

Science.gov (United States)

Michael G. Ryan

2008-01-01

Forests store much carbon and their growth can be a carbon sink if disturbance or harvesting has killed or removed trees or if trees that can now regrow are planted where they did not historically occur. Forests and long-lived wood products currently offset 310 million metric tons of U.S. fossil fuel emissions of carbon--20 percent of the total (Pacala et al. 2007)....

Biodegradation of the High Explosive Hexanitrohexaazaiso-wurtzitane (CL-20

Directory of Open Access Journals (Sweden)

Steve Nicolich

2009-04-01

Full Text Available The aerobic biodegradability of the high explosive CL-20 by activated sludge and the white rot fungus Phanerochaete chrysosporium has been investigated. Although activated sludge is not effective in degrading CL-20 directly, it can mineralize the alkaline hydrolysis products. Phanerochaete chrysosporium degrades CL-20 in the presence of supplementary carbon and nitrogen sources. Biodegradation studies were conducted using various nutrient media under diverse conditions. Variables included the CL-20 concentration; levels of carbon (as glycerol and ammonium sulfate and yeast extract as sources of nitrogen. Cultures that received CL-20 at the time of inoculation transformed CL-20 completely under all nutrient conditions studied. When CL-20 was added to pre-grown cultures, degradation was limited. The extent of mineralization was monitored by the 14CO2 time evolution; up to 51% mineralization was achieved when the fungus was incubated with [14C]-CL-20. The kinetics of CL-20 biodegradation by Phanerochaete chrysosporium follows the logistic kinetic growth model.

The research of a method for determination of total carbon, combination carbon and free carbon in beryllium metal

International Nuclear Information System (INIS)

Yang Xingzhong; Zhu Xiaohong

1996-02-01

A method for determination of total carbon, combination carbon and free carbon in beryllium metal with LECO CS-344 carbon/sulphur determinant has been studied. Tungsten-copper mixed pellets are used as flux to the determination of total carbon. Ratio of weight of the flux to the sample is greater than 20:1. Good analytical results are got. By this method the relative standard deviation is <10% when the content of total carbon in the range of 0.050%∼0.080% in beryllium. A standard steel sample of carbon is added into beryllium, the recoveries are 94%∼106%. For determination of free carbon, the sample are decomposed with 3 mol/L HCl, filtered and followed determination. By this method the relative standard deviation is ≤10% when the content of free carbon in the range of 0.006%∼0.020% in beryllium. the balance of total carbon and free carbon is equal to combination carbon. The method is used to determine the sample of content of total carbon in the range of 0.050%∼1.00%, free carbon in the range of 0.006%∼0.500% in metal beryllium. (6 refs., 1 fig., 13 tabs.)

The Influence of Calcium Carbonate Composition and Activated Carbon in Pack Carburizing Low Carbon Steel Process in The Review of Hardness and Micro Structure

Science.gov (United States)

Hafni; Hadi, Syafrul; Edison

2017-12-01

Carburizing is a way of hardening the surface by heating the metal (steel) above the critical temperature in an environment containing carbon. Steel at a temperature of the critical temperature of affinity to carbon. Carbon is absorbed into the metal form a solid solution of carbon-iron and the outer layer has high carbon content. When the composition of the activator and the activated charcoal is right, it will perfect the carbon atoms to diffuse into the test material to low carbon steels. Thick layer of carbon Depending on the time and temperature are used. Pack carburizing process in this study, using 1 kg of solid carbon derived from coconut shell charcoal with a variation of 20%, 10% and 5% calcium carbonate activator, burner temperature of 950 0C, holding time 4 hours. The test material is low carbon steel has 9 pieces. Each composition has three specimens. Furnace used in this study is a pack carburizing furnace which has a designed burner box with a volume of 1000 x 600 x 400 (mm3) of coal-fired. Equipped with a circulation of oxygen from the blower 2 inches and has a wall of refractory bricks. From the variation of composition CaCO3, microstructure formed on the specimen with 20% CaCO3, better diffusion of carbon into the carbon steel, it is seen by the form marten site structure after quenching, and this indicates that there has been an increase of or adding carbon to in the specimen. This led to the formation of marten site specimen into hard surfaces, where the average value of hardness at one point side (side edge) 31.7 HRC

Synthesis of position-specific tritium-labeled 20(S)-camptothecin, 9-amino-20(S)-camptothecin, and 10,11-methylenedioxy-20(S)-camptothecin. [Anticancer agents

Energy Technology Data Exchange (ETDEWEB)

Nicholas, A.W.; Wani, M.C.; Wall, M.E.; Kepler, J.A.; Taylor, G.F. (Research Triangle Inst., Research Triangle Park, NC (United States))

1993-09-01

The synthesis is given for three ring A tritiated camptothecin (CPT) analogs as biological probes in the study of the parent compounds which are of current widespread interest as potent anticancer agents. The strategy of catalytic tritolysis of aryl halide bonds was employed, and thus the preparations of the requisite precursors 9-chloro-20(S)-CPT, 9-amino-10,12-dibromo-20(S)-CPT, and 9-chloro-10,11-methylenedioxy-20(S)-CPT are given; catalytic tritiation of these respective precursors under polar, alkaline solvent conditions using palladium/carbon provides smooth conversion to [9-[sup 3]H]-20(S)-CPT, 9-amino-[1012[sup 3]H]-20(S)-CPT, and [9-[sup 3]H]-10,11-methylenedioxy-20(S)-CPT. (author).

Improvement in char formability of phenolic resin for development of Carbon/Carbon composites

International Nuclear Information System (INIS)

Hajhosseini, M.; Payami, A.; Ghaffarian, S. R.; Rezadoust, A. M.

2008-01-01

In the processing of carbon/carbon composites using polymer resin as the matrix precursor, it is inevitable that a porous structure was formed after carbonization. As a result, densification by liquid phase impregnation followed by recarbonization is required to obtain a densified composite. Consequently, the char formability of resin is an important factor in reducing the number of densification cycles and hence the processing cost. In this study, a novel approach is adopted to improve the densification of carbon/carbon composites by using a new phenolic resin modified by pitch. For this purpose, soluble part of pitch was extracted and dispersed in resol type phenolic resin. The polymerization reaction was performed in presence of para-formaldehyde and a resol-pitch compound was obtained. The second compound was prepared by mixing novolac-furfural in 55:45 weight ratio containing 9% by weight hexamethylene tetramine. This compound was added to resol-pitch compound in 10,20,50 and 80 w %. The microstructure of carbonized resin was investigated by X-ray diffraction and char yield, and the linear and volumetric shrinkage were obtained. Results show that in 80:20 ratio of resol-pitch to novolac-furfural , the char yield would be maximized by 71% and volumetric shrinkage would be minimized at 16.4%. At the same time, XRD results indicate that the resin has a strong ability to graphitize carbon/carbon composites matrix as a necessary step for its processing

Comparison of carbon onions and carbon blacks as conductive additives for carbon supercapacitors in organic electrolytes

Science.gov (United States)

Jäckel, N.; Weingarth, D.; Zeiger, M.; Aslan, M.; Grobelsek, I.; Presser, V.

2014-12-01

This study investigates carbon onions (∼400 m2 g-1) as a conductive additive for supercapacitor electrodes of activated carbon and compares their performance with carbon black with high or low internal surface area. We provide a study of the electrical conductivity and electrochemical behavior between 2.5 and 20 mass% addition of each of these three additives to activated carbon. Structural characterization shows that the density of the resulting film electrodes depends on the degree of agglomeration and the amount of additive. Addition of low surface area carbon black (∼80 m2 g-1) enhances the power handling of carbon electrodes but significantly lowers the specific capacitance even when adding small amounts of carbon black. A much lower decrease in specific capacitance is observed for carbon onions and the best values are seen for carbon black with a high surface area (∼1390 m2 g-1). The overall performance benefits from the addition of any of the studied additives only at either high scan rates and/or electrolytes with high ion mobility. Normalization to the volume shows a severe decrease in volumetric capacitance and only at high current densities nearing 10 A g-1 we can see an improvement of the electrode capacitance.

Hurricane impacts on US forest carbon sequestration

Science.gov (United States)

Steven G. McNulty

2002-01-01

Recent focus has been given to US forests as a sink for increases in atmospheric carbon dioxide. Current estimates of US Forest carbon sequestration average approximately 20 Tg (i.e. 1012 g) year. However, predictions of forest carbon sequestration often do not include the influence of hurricanes on forest carbon storage. Intense hurricanes...

Economic effects of using carbon taxes to reduce carbon dioxide emissions in major OECD countries. Final report

International Nuclear Information System (INIS)

1992-01-01

A tax on fossil fuels designed to obtain a 20 percent reduction in emissions of carbon dioxide by the year 2020 would lower output among major OECD nations by 1 to 3 1/2 percent. The tax required to achieve a 20% reduction in emissions of carbon dioxide by 2020 ranged from $489.4 (Sweden) per metric ton of carbon to $2,427.9 (Japan) per ton of carbon. The tax required for the U.S. was $720.6 per ton. In the U.S., a tax per $100 per ton of carbon would equate to a tax of $70.68 per short ton of coal, $11.42 per barrel of oil, $1.66 per MCF of natural gas and 0.27 per gallon of gasoline. The study is part of a multi-phase effort to gauge the economic consequences of various measures being discussed by the international community to mitigate the possibility of global climate change by limiting emissions of carbon dioxide from fossil fuel use. The study assumed that the carbon tax program would be revenue neutral in that increased revenues from the carbon tax would be offset by reductions in personal income taxes

46 CFR 194.20-7 - Fire protection.

Science.gov (United States)

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Fire protection. 194.20-7 Section 194.20-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS HANDLING, USE... Fire protection. (a) Each chemical storeroom shall be protected by a fixed automatic carbon dioxide...

Molecular Basis of Microbial One-Carbon Metabolism 2008 Gordon Research Conference (July 20-25, 2008)

Energy Technology Data Exchange (ETDEWEB)

Stephen W. Ragsdale

2009-08-12

One-carbon (C-1) compounds play a central role in microbial metabolism. C-1 compounds include methane, carbon monoxide, CO2, and methanol as well as coenzyme-bound one-carbon compounds (methyl-B12, CH3-H4folate, etc). Such compounds are of broad global importance because several C-1 compounds (e.g., CH4) are important energy sources, some (e.g., CO2 and CH4) are potent greenhouse gases, and others (e.g., CH2Cl2) are xenobiotics. They are central in pathways of energy metabolism and carbon fixation by microbes and many are of industrial interest. Research on the pathways of one-carbon metabolism has added greatly to our understanding of evolution, structural biology, enzyme mechanisms, gene regulation, ecology, and applied biology. The 2008 meeting will include recent important findings in the following areas: (a) genomics, metagenomics, and proteomic studies that have expanded our understanding of autotrophy and C-1 metabolism and the evolution of these pathways; (b) redox regulation of carbon cycles and the interrelationship between the carbon cycle and other biogeochemical cycles (sulfur, nitrogen, oxygen); (c) novel pathways for carbon assimilation; (d) biotechnology related to C-1 metabolism; (e) novel enzyme mechanisms including channeling of C-1 intermediates during metabolism; and (f) the relationship between metal homeostasis and the global carbon cycle. The conference has a diverse and gender-balanced slate of speakers and session leaders. The wide variety of disciplines brought to the study of C-1 metabolism make the field an excellent one in which to train young researchers.

A significant carbon sink in temperate forests in Beijing: based on 20-year field measurements in three stands.

Science.gov (United States)

Zhu, JianXiao; Hu, XueYang; Yao, Hui; Liu, GuoHua; Ji, ChenJun; Fang, JingYun

2015-11-01

Numerous efforts have been made to characterize forest carbon (C) cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stocks and fluxes in three permanent temperate forest plots (birch, oak and pine forest) during 2011–2014, and calculated the changes of the components of the C cycle related to the measurements during 1992–1994 at Mt. Dongling, Beijing, China. Forest net primary production in birch, oak, and pine plots was 5.32, 4.53, and 6.73 Mg C ha-1 a-1, respectively. Corresponding net ecosystem production was 0.12, 0.43, and 3.53 Mg C ha-1 a-1. The C stocks and fluxes in 2011–2014 were significantly larger than those in 1992–1994 in which the biomass C densities in birch, oak, and pine plots increased from 50.0, 37.7, and 54.0 Mg C ha-1 in 1994 to 101.5, 77.3, and 110.9 Mg C ha-1 in 2014; soil organic C densities increased from 207.0, 239.1, and 231.7 Mg C ha-1 to 214.8, 241.7, and 238.4 Mg C ha-1; and soil heterotrophic respiration increased from 2.78, 3.49, and 1.81 Mg C ha-1 a-1 to 5.20, 4.10, and 3.20 Mg C ha-1 a-1. These results suggest that the mountainous temperate forest ecosystems in Beijing have served as a carbon sink in the last two decades. These observations of C stocks and fluxes provided field-based data for a long-term study of C cycling in temperate forest ecosystems.

Carbon and water balance of European croplands throughout the 20th century

Science.gov (United States)

Gervois, SéBastien; Ciais, Philippe; de Noblet-Ducoudré, Nathalie; Brisson, Nadine; Vuichard, Nicolas; Viovy, Nicolas

2008-06-01

We assessed the effects of rising atmospheric CO2, changing climate, and farmers' practice on the carbon and water balance of European croplands during the past century (1901-2000). The coupled vegetation-crop model ORCHIDEE-STICS is applied over western Europe for C3 crops (winter wheat) and for maize, with prescribed historical agricultural practice changes. Not surprisingly, the enormous crop yield increase observed in all European regions, 300-400% between 1950 and 2000, is found to be dominantly explained by improved practice and varieties selection, rather than by rising CO2 (explaining a ˜11% uniform increase in yield) and changing climate (no further change in yield on average, but causing a decrease of ˜19% in the southern Iberian Peninsula). Agricultural soil carbon stocks in Europe are modeled to have decreased between 1950 and 1970, and since then to have increased again. Thus, the current stocks only differ by 1 ± 6 tC ha-1 from their 1900 value. Compensating effects of increasing yields on the one hand (increasing stocks) and of higher harvest index values and ploughing on the other hand (decreasing stocks) occur. Each of these processes taken individually has the potential to strongly alter the croplands soil carbon balance in the model. Consequently, large uncertainties are associated to the estimated change in carbon stocks between 1901 and 2001, roughly ±6 tC ha-1 a-1. In our most realistic simulation, the current cropland carbon balance is a net sink of 0.16 ± 0.15 tC ha-1 a-1. The annual water balance of cropland soils is influenced by increasing crop water use efficiency, one third of which is caused by rising CO2. However, increasing water use efficiency occurred mainly in spring and winter, when water is not limiting for plant growth, whereas no strong savings of soil water are achieved in summer through elevated CO2. Overall, trends in cultivation practices have caused a 3 times larger increase of water use efficiency than rising CO2.

A supercritical carbon dioxide plasma process for preparing tungsten oxide nanowires

International Nuclear Information System (INIS)

Kawashima, Ayato; Nomura, Shinfuku; Toyota, Hiromichi; Takemori, Toshihiko; Mukasa, Shinobu; Maehara, Tsunehiro

2007-01-01

A supercritical carbon dioxide (CO 2 ) plasma process for fabricating one-dimensional tungsten oxide nanowires coated with amorphous carbon is presented. High-frequency plasma was generated in supercritical carbon dioxide at 20 MPa by using tungsten electrodes mounted in a supercritical cell, and subsequently an organic solvent was introduced with supercritical carbon dioxide into the plasma. Electron microscopy and Raman spectroscopy investigations of the deposited materials showed the production of tungsten oxide nanowires with or without an outer layer. The nanowires with an outer layer exhibited a coaxial structure with an outer concentric layer of amorphous carbon and an inner layer of tungsten oxide with a thickness and diameter of 20-30 and 10-20 nm, respectively

INFLUENCE RESEARCH OF COLD PLASTIC DEFORMATION ON DIFFUSION SATURATION PROCESS BY CARBON AND BORON OF THE LOW-CARBON AND BORON-CONTAINING ALLOYS

Directory of Open Access Journals (Sweden)

N. Yu. Filonenko

2010-06-01

Full Text Available This work is devoted to the study of influence of cold prestrain with degree of deformation within the range 0…40 % on diffusion saturation with boron and carbon for low-carbon and boron steels. It is determined that the plastic prestrain with degree of deformation 20 % at temperature 750 °С for the low-carbon steel promote increasing of boron-cementation layer thickness by 25 % and microhardness of perlite layer by 20 %.

Phosphorus and nitrogen-containing carbons obtained by the carbonization of conducting polyaniline complex with phosphites

Czech Academy of Sciences Publication Activity Database

Bober, Patrycja; Trchová, Miroslava; Morávková, Zuzana; Kovářová, Jana; Vulić, I.; Gavrilov, N.; Pašti, I. A.; Stejskal, Jaroslav

2017-01-01

Roč. 246, 20 August (2017), s. 443-450 ISSN 0013-4686 R&D Projects: GA ČR(CZ) GA16-02787S Institutional support: RVO:61389013 Keywords : carbonization * conducting polymer * nitrogen-containing carbon Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 4.798, year: 2016

Carbon isotope fractionation between amorphous calcium carbonate and calcite in earthworm-produced calcium carbonate

International Nuclear Information System (INIS)

Versteegh, E.A.A.; Black, S.; Hodson, M.E.

2017-01-01

In this study we investigate carbon isotope fractionation during the crystallization of biogenic calcium carbonate. Several species of earthworm including Lumbricus terrestris secrete CaCO_3. Initially a milky fluid comprising micro-spherules of amorphous CaCO_3 (ACC) is secreted into pouches of the earthworm calciferous gland. The micro-spherules coalesce and crystalize to form millimetre scale granules, largely comprising calcite. These are secreted into the earthworm intestine and from there into the soil. L. terrestris were cultured for 28 days in two different soils, moistened with three different mineral waters at 10, 16 and 20 °C. The milky fluid in the calciferous glands, granules in the pouches of the calciferous glands and granules excreted into the soil were collected and analysed by FTIR spectroscopy to determine the form of CaCO_3 present and by IRMS to determine δ"1"3C values. The milky fluid was ACC. Granules removed from the pouches and soil were largely calcite; the granules removed from the pouches contained more residual ACC than those recovered from the soil. The δ"1"3C values of milky fluid and pouch granules became significantly more negative with increasing temperature (p ≤ 0.001). For samples from each temperature treatment, δ"1"3C values became significantly (p ≤ 0.001) more negative from the milky fluid to the pouch granules to the soil granules (−13.77, −14.69 and −15.00 respectively at 10 °C; −14.37, −15.07 and −15.18 respectively at 16 °C and −14.89, −15.41 and −15.65 respectively at 20 °C). Fractionation of C isotopes occurred as the ACC recrystallized to form calcite with the fractionation factor ε_c_a_l_c_i_t_e_-_A_C_C = −1.20 ± 0.52‰. This is consistent with the crystallization involving dissolution and reprecipitation rather than a solid state rearrangement. Although C isotopic fractionation has previously been described between different species of dissolved inorganic carbon

Biosynthesis of glycerol carbonate from glycerol by lipase in dimethyl carbonate as the solvent.

Science.gov (United States)

Lee, Kyung Hwa; Park, Chang-Ho; Lee, Eun Yeol

2010-11-01

Glycerol carbonate was synthesized from renewable glycerol and dimethyl carbonate using lipase in solvent-free reaction system in which excess dimethyl carbonate played as the reaction medium. A variety of lipases have been tested for their abilities to catalyze transesterification reaction, and Candida antartica lipase B and Novozyme 435 exhibited higher catalytic activities. The silica-coated glycerol with a 1:1 ratio was supplied to prevent two-phase formation between hydrophobic dimethyl carbonate and hydrophilic glycerol. Glycerol carbonate was successfully synthesized with more than 90% conversion from dimethyl carbonate and glycerol with a molar ratio of 10 using Novozyme 435-catalyzed transesterification at 70 °C. The Novozyme 435 [5% (w/w) and 20% (w/w)] and silica gel were more than four times recycled with good stability in a repeated batch operation for the solvent-free synthesis of glycerol carbonate.

Aligning climate policy with finance ministers' G20 agenda

Science.gov (United States)

Edenhofer, Ottmar; Knopf, Brigitte; Bak, Céline; Bhattacharya, Amar

2017-07-01

There is no longer a choice between climate policy and no climate policy. G20 finance ministers have to play a key role in implementing smart climate policies like carbon pricing. Yet they remain reluctant to take advantage of the merits of carbon pricing for sound fiscal policy.

Calcium silicate structure and carbonation shrinkage of a tobermorite-based material

International Nuclear Information System (INIS)

Matsushita, Fumiaki; Aono, Yoshimichi; Shibata, Sumio

2004-01-01

Carbonated autoclaved aerated concretes (AACs) show no shrinkage at a degree of carbonation approximately less than 20%. The 29 Si MAS NMR spectrum showed that at a degree of carbonation less than 25%, the typical double-chain silicate anion structure of tobermorite-11A was well maintained and interlayer Ca ions were exchanged with protons. This corresponded to the absence of carbonation shrinkage at a degree of carbonation less than 20%. When the degree of carbonation increased from 25% to 50% up to 60%, the double-chain silicate anion structure of tobermorite-11A was decomposed and Ca ions in the Ca-O layers were dissolved, showing a possible mechanism of carbonation shrinkage

Modified glassy carbon electrodes based on carbon nanostructures for ultrasensitive electrochemical determination of furazolidone

Energy Technology Data Exchange (ETDEWEB)

Shahrokhian, Saeed, E-mail: shahrokhian@sharif.edu [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Naderi, Leila [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of); Ghalkhani, Masoumeh [Department of Chemistry, Faculty of Science, Shahid Rajaee Teacher Training University, Lavizan, Tehran (Iran, Islamic Republic of); Institute for advanced technology, Shahid Rajaee Teacher Training University, Lavizan, Tehran, 16788 (Iran, Islamic Republic of)

2016-04-01

The electrochemical behavior of Furazolidone (Fu) was investigated on the surface of the glassy carbon electrode modified with different carbon nanomaterials, including carbon nanotubes (CNTs), carbon nanoparticles (CNPs), nanodiamond-graphite (NDG), graphene oxide (GO), reduced graphene oxide (RGO) and RGO-CNT hybrids (various ratios) using linear sweep voltammetry (LSV). The results of voltammetric studies exhibited a considerable increase in the cathodic peak current of Fu at the RGO modified GCE, compared to other modified electrodes and also bare GCE. The surface morphology and nature of the RGO film was thoroughly characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The modified electrode showed two linear dynamic ranges of 0.001–2.0 μM and 2.0–10.0 μM with a detection limit of 0.3 nM for the voltammetric determination of Fu. This sensor was used successfully for Fu determination in pharmaceutical and clinical preparations. - Highlights: • The electrochemical behavior of Furazolidone (Fu) was investigated on the surface of the modified electrode with different carbon nanomaterials by Linear sweep voltammetry. • Two linear dynamic ranges and a low detection limit were obtained. • The modified electrode was applied for the detection of Fu in pharmaceutical and clinical preparations.

Natural disturbance impacts on Canada's forest carbon budget

International Nuclear Information System (INIS)

Kurz, W.

2004-01-01

Wildfire and insect outbreaks are major determinants of forest dynamics in Canada, transferring carbon within the ecosystem, releasing carbon into the atmosphere and influencing post-disturbance carbon dynamics. This paper discusses the impacts of global climate change on natural disturbances. Higher temperatures and drier conditions are likely to increase burned areas in Canada and will also increase the impacts of insects, allowing for an expanded range and stressing their host species. Long-term changes in disturbance regimes have already affected Canada's forest age-class structure. Statistics of lower disturbance periods and carbon production were compared with periods of higher disturbance. Scenario analyses were conducted for the period of 1996 to 2032, assuming that annual insect and fire disturbance rates in timber-productive forests were 20 per cent higher and carbon production 20 per cent lower than base scenarios using average disturbance rates. It was concluded that these conditions could cause carbon stocks in Canada's forests to decline. The future carbon balance of Canada's forests will be affected by the rate of natural and human-induced disturbances. 4 refs

Formation of carbon quantum dots and nanodiamonds in laser ablation of a carbon film

Science.gov (United States)

Sidorov, A. I.; Lebedev, V. F.; Kobranova, A. A.; Nashchekin, A. V.

2018-01-01

We have experimentally shown that nanosecond near-IR pulsed laser ablation of a thin amorphous carbon film produces carbon quantum dots with a graphite structure and nanodiamonds with a characteristic size of 20 - 500 nm on the substrate surface. The formation of these nanostructures is confirmed by electron microscopic images, luminescence spectra and Raman spectra. The mechanisms explaining the observed effects are proposed.

Accounting for Organic Carbon Change in Deep Soil Altered Carbon Sequestration Efficiency

Science.gov (United States)

Li, J.; Liang, F.; Xu, M.; Huang, S.

2017-12-01

Study on soil organic carbon (SOC) sequestration under fertilization practices in croplands lacks information of soil C change at depth lower than plow layer (i.e. 20 30-cm). By synthesizing long-term datasets of fertilization experiments in four typical Chinese croplands representing black soil at Gongzhuling(GZL), aquatic Chao soil at Zhengzhou(ZZ), red soil at Qiyang(QY) and purple soil at Chongqing(CQ) city, we calculated changes in SOC storage relative to initial condition (ΔSOC) in 0-20cm and 0-60cm, organic C inputs (OC) from the stubble, roots and manure amendment, and C sequestration efficiency (CSE: the ratio of ΔSOC over OC) in 0-20cm and 0-60cm. The fertilization treatments include cropping with no fertilization (CK), chemical nitrogen, phosphorus and potassium fertilizers (NPK) and combined chemical fertilizers and manure (NPKM). Results showed SOC storage generally decreased with soil depth (i.e. 0-20 > 20-40, 40-60 cm) and increased with fertilizations (i.e. initial fertilizations, soil at depth (>20cm) can act as important soil carbon sinks in intrinsically high fertility soils (i.e. black soil) but less likely at poor fertility soil (i.e. aquatic Chao soil). It thus informs the need to account for C change in deep soils for estimating soil C sequestration capacity particularly with indigenously fertile cropland soils.

Conducting carbonized polyaniline nanotubes

International Nuclear Information System (INIS)

Mentus, Slavko; Ciric-Marjanovic, Gordana; Trchova, Miroslava; Stejskal, Jaroslav

2009-01-01

Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min -1 up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 μm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 μm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm -1 , increased to 0.7 S cm -1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

Conducting carbonized polyaniline nanotubes

Energy Technology Data Exchange (ETDEWEB)

Mentus, Slavko; Ciric-Marjanovic, Gordana [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade (Serbia); Trchova, Miroslava; Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Square 2, 162 06 Prague 6 (Czech Republic)], E-mail: gordana@ffh.bg.ac.rs

2009-06-17

Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min{sup -1} up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 {mu}m, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 {mu}m, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm{sup -1}, increased to 0.7 S cm{sup -1} upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

Carbon nanotubes and methods of making carbon nanotubes

KAUST Repository

Basset, Jean-Marie

2017-04-27

Embodiments of the present disclosure provide for methods that can be used to produce carbon nanotubes (hereinafter CNT) having an inner diameter about 5-55 nm, methods of tuning the inner diameter of CNTs (e.g., by adjusting reaction pressure), CNTs having an inner diameter of greater than 20 nm or more, and the like.

Applications for alliform carbon

Energy Technology Data Exchange (ETDEWEB)

Gogotsi, Yury; Mochalin, Vadym; McDonough, IV, John Kenneth; Simon, Patrice; Taberna, Pierre Louis

2017-02-21

This invention relates to novel applications for alliform carbon, useful in conductors and energy storage devices, including electrical double layer capacitor devices and articles incorporating such conductors and devices. Said alliform carbon particles are in the range of 2 to about 20 percent by weight, relative to the weight of the entire electrode. Said novel applications include supercapacitors and associated electrode devices, batteries, bandages and wound healing, and thin-film devices, including display devices.

High-surface-area active carbon

International Nuclear Information System (INIS)

O'Grady, T.M.; Wennerberg, A.N.

1986-01-01

This paper describes the preparation and properties of a unique active carbon having exceptionally high surface areas, over 2500 m 2 /gm, and extraordinary adsorptive capacities. The carbon is made by a direct chemical activation route in which petroleum coke or other carbonaceous sources are reacted with excess potassium hydroxide at 400 0 to 500 0 C to an intermediate product that is subsequently pyrolyzed at 800 0 to 900 0 C to active carbon containing potassium salts. These are removed by water washing and the carbon is dried to produce a powdered product. A granular carbon can also be made by further processing the powdered carbon by using specialized granulation techniques. Typical properties of the carbon include Iodine Numbers of 3000 to 3600, methylene blue adsorption of 650 to 750 mg/gm, pore volumes of 2.0 to 2.6 cc/gm and less than 3.0% ash. This carbon's high adsorption capacities make it uniquely suited for numerous demanding applications in the medical area, purifications, removal of toxic substances, as catalyst carriers, etc

Toward explaining the Holocene carbon dioxide and carbon isotope records: Results from transient ocean carbon cycle-climate simulations

Science.gov (United States)

Menviel, L.; Joos, F.

2012-03-01

The Bern3D model was applied to quantify the mechanisms of carbon cycle changes during the Holocene (last 11,000 years). We rely on scenarios from the literature to prescribe the evolution of shallow water carbonate deposition and of land carbon inventory changes over the glacial termination (18,000 to 11,000 years ago) and the Holocene and modify these scenarios within uncertainties. Model results are consistent with Holocene records of atmospheric CO2 and δ13C as well as the spatiotemporal evolution of δ13C and carbonate ion concentration in the deep sea. Deposition of shallow water carbonate, carbonate compensation of land uptake during the glacial termination, land carbon uptake and release during the Holocene, and the response of the ocean-sediment system to marine changes during the termination contribute roughly equally to the reconstructed late Holocene pCO2 rise of 20 ppmv. The 5 ppmv early Holocene pCO2 decrease reflects terrestrial uptake largely compensated by carbonate deposition and ocean sediment responses. Additional small contributions arise from Holocene changes in sea surface temperature, ocean circulation, and export productivity. The Holocene pCO2 variations result from the subtle balance of forcings and processes acting on different timescales and partly in opposite direction as well as from memory effects associated with changes occurring during the termination. Different interglacial periods with different forcing histories are thus expected to yield different pCO2 evolutions as documented by ice cores.

20 years of Black Carbon measurements in Germany

Science.gov (United States)

Kutzner, Rebecca; Quedenau, Jörn; Kuik, Friderike; von Schneidemesser, Erika; Schmale, Julia

2016-04-01

Black Carbon (BC) is an important short-lived climate-forcing pollutant contributing to global warming through absorption of sunlight. At the same time, BC, as a component of particulate matter (PM) exerts adverse health effects, like decreased lung function and exacerbated asthma. Globally, anthropogenic emission sources of BC include residential heating, transport, and agricultural fires, while the dominant natural emission sources are wildfires. Despite the various adverse effects of BC, legislation that requires mandatory monitoring of BC concentrations does not currently exist in the European Union. Instead, BC is only indirectly monitored as component of PM10 and PM2.5 (particulate matter with a diameter smaller 10 μm and 2.5 μm). Before the introduction of mandatory PM10 and PM2.5 monitoring in the European Union in 2005 and 2015, respectively, 'black smoke', a surrogate for BC, was a required measurement in Germany from the early 1990s. The annual mean limit value was 14 μg m-3 from 1995 and 8 μg m-3 from 1998 onwards. Many 'black smoke' measurements were stopped in 2004, with the repeal of the regulations obtaining at the time. However, in most German federal states a limited number BC monitoring stations continued to operate. Here we present a synthesis of BC data from 213 stations across Germany covering the period between 1994 and 2014. Due to the lack of a standardized method and respective legislation, the data set is very heterogeneous relying on twelve different measurement methods including chemical, optical, and thermal-optical methods. Stations include locations classified as background, urban-background, industrial and traffic among other types. Raw data in many different formats has been modelled and integrated in a relational database, allowing various options for further data analysis. We highlight results from the year 2009, as it is the year with the largest measurement coverage based on the same measurement method, with 30 stations. In

Carbon dioxide as a venous contrast agent: Applications in interventional radiology=20

International Nuclear Information System (INIS)

Hahn, Seong Tae; Lee, Jae Mun; Kim, Choon Yul; Shinn, Kyung Sub; Pfammatter, Thomas; Cho, Kyung Jae

1997-01-01

To evaluate the safety and usefulness of carbon dioxide(CO 2 ) as a venous contrast agent for upper-arm placement of peripherally inserted central venous catheter (PICC), vena caval filter placement, and for visualization of the portal vein in transjugular intrahepatic portosystemic shunt(TIPS). About 20-30ml of CO 2 was used as an alternative to iodinated contrast material for digital subtraction angiography (DSA) and fluoroscopy to guide upper-arm placement of PICC in 46 patients, for inferior venacavogram before filter placement in five, and for visualization of the portal vein during TIPS in two. Vital signs, peripheral arterial oxygen saturation, and renal function were checked during and after delivery of CO 2 . All CO 2 DSA for PICC placement clearly delineated patency or stenosis of the central veins. In 41 of 46 patients (89 %), PICC placement with CO 2 guidance was successful. The mean number of venipunctures for PICC placement was 1.9, and the mean volume of CO 2 injected for venipuncture was 35ml. In five patients, Titanium Greenfield filters were successfully implanted into the inferior vena cava following CO 2 vena cavography. In two patients in whom hepatopetal portal flow was seen on indirect portography, the portal vein was visualized by CO 2 -wedged hepatic venography. Injection of CO 2 into the splenic vein following TIPS placement revealed shunt patency. Vital signs and oxygen saturation did not change, and there was no evidence of renal toxicity following CO 2 injection. CO 2 is a safe and useful alternative contrast agent for upper-arm placement of PICC, pre-filter placement cavography, and wedged hepatic venography and portography for TIPS

Biodegradation of the High Explosive Hexanitrohexaazaiso-wurtzitane (CL-20)

OpenAIRE

Karakaya, Pelin; Christodoulatos, Christos; Koutsospyros, Agamemnon; Balas, Wendy; Nicolich, Steve; Sidhoum, Mohammed

2009-01-01

The aerobic biodegradability of the high explosive CL-20 by activated sludge and the white rot fungus Phanerochaete chrysosporium has been investigated. Although activated sludge is not effective in degrading CL-20 directly, it can mineralize the alkaline hydrolysis products. Phanerochaete chrysosporium degrades CL-20 in the presence of supplementary carbon and nitrogen sources. Biodegradation studies were conducted using various nutrient media under diverse conditions. Variables included the...

Multi-walled Carbon Nanotubes/Graphite Nanosheets Modified Glassy Carbon Electrode for the Simultaneous Determination of Acetaminophen and Dopamine.

Science.gov (United States)

Zhang, Susu; He, Ping; Zhang, Guangli; Lei, Wen; He, Huichao

2015-01-01

Graphite nanosheets prepared by thermal expansion and successive sonication were utilized for the construction of a multi-walled carbon nanotubes/graphite nanosheets based amperometric sensing platform to simultaneously determine acetaminophen and dopamine in the presence of ascorbic acid in physiological conditions. The synergistic effect of multi-walled carbon nanotubes and graphite nanosheets catalyzed the electrooxidation of acetaminophen and dopamine, leading to a remarkable potential difference up to 200 mV. The as-prepared modified electrode exhibited linear responses to acetaminophen and dopamine in the concentration ranges of 2.0 × 10(-6) - 2.4 × 10(-4) M (R = 0.999) and 2.0 × 10(-6) - 2.0 × 10(-4) M (R = 0.998), respectively. The detection limits were down to 2.3 × 10(-7) M for acetaminophen and 3.5 × 10(-7) M for dopamine (S/N = 3). Based on the simple preparation and prominent electrochemical properties, the obtained multi-walled carbon nanotubes/graphite nanosheets modified electrode would be a good candidate for the determination of acetaminophen and dopamine without the interference of ascorbic acid.

Characteristics of Sodium Polyacrylate/Nano-Sized Carbon Hydrogel for Biomedical Patch.

Science.gov (United States)

Park, Jong-Kyu; Seo, Sun-Kyo; Cho, Seungkwan; Kim, Han-Sung; Lee, Chi-Hwan

2018-03-01

Conductive hydrogels were prepared for biomedical patch in order to improve the electrical conductivity. Sodium polyacrylate and nano-sized carbon were mixed and fabricated by aqueous solution gelation process in various contents of nano-sized carbon with 0.1, 0.5, 1.0 and 2.0 wt%. Sodium polyacrylate/nano-sized carbon conductive hydrogels were investigated by molecular structure, surface morphology and electrical conductivity. The conductivity of the hydrogel/nano-sized carbon conductive hydrogel proved to be 10% higher than conductive hydrogel without nano-sized carbon. However, it was founded that conductive hydrogels with nano-sized carbon content from 0.5 up to 2.0 wt% were remarkably decreased. This may be due to the non-uniform distribution of nano-sized carbon, resulting from agglomerates of nano-sized carbon. The developed hydrogel is intended for use in the medical and cosmetic fields that is applicable to supply micro-current from device to human body.

Corrosion behavior of carbon steel in wet Na-bentonite medium

International Nuclear Information System (INIS)

Yeon, Jae-Won; Ha, Young-Kyoung; Choi, In-Kyu; Chun, Kwan-Sik

1996-01-01

Corrosion behaviors of carbon steel in wet Na-bentonite medium were studied. Corrosion rate of carbon steel in wet bentonite was measured to be 20 μm/yr at 25 deg C using the AC impedance technique. This value is agreed with that obtained by weight loss at 40 deg C for 1 year. The effect of bicarbonate ion on the corrosion of carbon steel in wet bentonite was also evaluated. The carbon steels in wet bentonite having 0.001, 0.01, and 0.1 M concentration of bicarbonate ion gave corrosion rates of 20, 8, and 0.2 μm/yr, respectively. Corrosion potentials of specimens were also measured and compared with the AC impedance results. Both results indicated that bicarbonate ion could effectively reduce the corrosion rate of carbon steels in bentonite due to the formation of protective layer on the carbon steel. (author)

Carbon-Carbon Composites as Recuperator Materials for Direct Gas Brayton Systems

International Nuclear Information System (INIS)

RA Wolf

2006-01-01

Of the numerous energy conversion options available for a space nuclear power plant (SNPP), one that shows promise in attaining reliable operation and high efficiency is the direct gas Brayton (GB) system. In order to increase efficiency, the GB system incorporates a recuperator that accounts for nearly half the weight of the energy conversion system (ECS). Therefore, development of a recuperator that is lighter and provides better performance than current heat exchangers could prove to be advantageous. The feasibility of a carbon-carbon (C/C) composite recuperator core has been assessed and a mass savings of 60% and volume penalty of 20% were projected. The excellent thermal properties, high-temperature capabilities, and low density of carbon-carbon materials make them attractive in the GB system, but development issues such as material compatibility with other structural materials in the system, such as refractory metals and superalloys, permeability, corrosion, joining, and fabrication must be addressed

Carbon-Carbon Composites as Recuperator Material for Direct Gas Brayton Systems

Energy Technology Data Exchange (ETDEWEB)

RA Wolf

2006-07-19

Of the numerous energy conversion options available for a space nuclear power plant (SNPP), one that shows promise in attaining reliable operation and high efficiency is the direct gas Brayton (GB) system. In order to increase efficiency, the GB system incorporates a recuperator that accounts for nearly half the weight of the energy conversion system (ECS). Therefore, development of a recuperator that is lighter and provides better performance than current heat exchangers could prove to be advantageous. The feasibility of a carbon-carbon (C/C) composite recuperator core has been assessed and a mass savings of 60% and volume penalty of 20% were projected. The excellent thermal properties, high-temperature capabilities, and low density of carbon-carbon materials make them attractive in the GB system, but development issues such as material compatibility with other structural materials in the system, such as refractory metals and superalloys, permeability, corrosion, joining, and fabrication must be addressed.

FutureGen 2.0 Pipeline and Regional Carbon Capture Storage Project - Final Report

Energy Technology Data Exchange (ETDEWEB)

Burger, Chris [Patrick Engineering Inc., Lisle, IL (United States); Wortman, David [Patrick Engineering Inc., Lisle, IL (United States); Brown, Chris [Battelle Memorial Inst., Richland, WA (United States); Hassan, Syed [Gulf Interstate Engineering, Houston, TX (United States); Humphreys, Ken [Futuregen Industrial Alliance, Inc., Washington, D.C. (United States); Willford, Mark [Futuregen Industrial Alliance, Inc., Washington, D.C. (United States)

2016-03-31

The U.S. Department of Energy’s (DOE) FutureGen 2.0 Program involves two projects: (1) the Oxy-Combustion Power Plant Project and (2) the CO2 Pipeline and Storage Project. This Final Technical Report is focused on the CO2 Pipeline and Storage Project. The FutureGen 2.0 CO2 Pipeline and Storage Project evolved from an initial siting and project definition effort in Phase I, into the Phase II activity consisting permitting, design development, the acquisition of land rights, facility design, and licensing and regulatory approvals. Phase II also progressed into construction packaging, construction procurement, and targeted early preparatory activities in the field. The CO2 Pipeline and Storage Project accomplishments were significant, and in some cases unprecedented. The engineering, permitting, legal, stakeholder, and commercial learnings substantially advance the nation’s understanding of commercial-scale CO2 storage in deep saline aquifers. Voluminous and significant information was obtained from the drilling and the testing program of the subsurface, and sophisticated modeling was performed that held up to a wide range of scrutiny. All designs progressed to the point of securing construction contracts or comfort letters attesting to successful negotiation of all contract terms and willing execution at the appropriate time all major project elements – pipeline, surface facilities, and subsurface – as well as operations. While the physical installation of the planned facilities did not proceed in part due to insufficient time to complete the project prior to the expiration of federal funding, the project met significant objectives prior to DOE’s closeout decision. Had additional time been available, there were no known, insurmountable obstacles that would have precluded successful construction and operation of the project. Due to the suspension of the project, site restoration activities were developed and the work was accomplished. The site restoration

Crystal structure of a diaryl carbonate: 1,3-phenylene bis(phenyl carbonate

Directory of Open Access Journals (Sweden)

Marina A. Solomos

2017-12-01

Full Text Available The whole molecule of the title compound, C20H14O6, is generated by mirror symmetry, the mirror bisecting the central benzene ring. The carbonate groups adopt an s-cis-s-cis conformation, with torsion angles of 58.7 (2 and 116.32 (15°. The crystal structure of 1,3-phenylene bis(phenyl carbonate contains no strong hydrogen bonds, though weak C—H...O and offset π–π interactions are observed, forming layers parallel to the ac plane.

Effet de l'amendement au carbonate de calcium (mikhart) de ...

African Journals Online (AJOL)

SARAH

31 janv. 2017 ... control substratum, SCa10 (S0 + 10 % powder of calcium carbonate), SCa20 (S0 + 20 % powder of calcium carbonate), SCa30 (S0 ..... puis montés sur un microscope électronique FEG Supra. 40 VP Zeiss à balayage et pression variable. Dès lors, ..... substrats amendés d'un apport en quantité et en qualité.

Thermodynamics on Soluble Carbon Nanotubes: How Do DNA Molecules Replace Surfactants on Carbon Nanotubes?

Science.gov (United States)

Kato, Yuichi; Inoue, Ayaka; Niidome, Yasuro; Nakashima, Naotoshi

2012-01-01

Here we represent thermodynamics on soluble carbon nanotubes that enables deep understanding the interactions between single-walled carbon nanotubes (SWNTs) and molecules. We selected sodium cholate and single-stranded cytosine oligo-DNAs (dCn (n = 4, 5, 6, 7, 8, 10, 15, and 20)), both of which are typical SWNT solubilizers, and successfully determined thermodynamic properties (ΔG, ΔH and ΔS values) for the exchange reactions of sodium cholate on four different chiralities of SWNTs ((n,m) = (6,5), (7,5), (10,2), and (8,6)) for the DNAs. Typical results contain i) the dC5 exhibited an exothermic exchange, whereas the dC6, 8, 10, 15, and 20 materials exhibited endothermic exchanges, and ii) the energetics of the dC4 and dC7 exchanges depended on the associated chiral indices and could be endothermic or exothermic. The presented method is general and is applicable to any molecule that interacts with nanotubes. The study opens a way for science of carbon nanotube thermodynamics. PMID:23066502

Old-growth forests can accumulate carbon in soils

Science.gov (United States)

Zhou, G.; Liu, S.; Li, Z.; Zhang, Dongxiao; Tang, X.; Zhou, C.; Yan, J.; Mo, J.

2006-01-01

Old-growth forests have traditionally been considered negligible as carbon sinks because carbon uptake has been thought to be balanced by respiration. We show that the top 20-centimeter soil layer in preserved old-growth forests in southern China accumulated atmospheric carbon at an unexpectedly high average rate of 0.61 megagrams of carbon hectare-1 year-1 from 1979 to 2003. This study suggests that the carbon cycle processes in the belowground system of these forests are changing in response to the changing environment. The result directly challenges the prevailing belief in ecosystem ecology regarding carbon budget in old-growth forests and supports the establishment of a new, nonequilibrium conceptual framework to study soil carbon dynamics.

Hydrogen storage properties of carbon nanomaterials and carbon containing metal hydrides

Energy Technology Data Exchange (ETDEWEB)

Maehlen, Jan Petter

2003-07-01

The topic of this thesis is structural investigations of carbon containing materials in respect to their hydrogen storage properties. This work was initially triggered by reports of extremely high hydrogen storage capacities of specific carbon nanostructures. It was decided to try to verify and understand the mechanisms in play in case of the existence of such high hydrogen densities in carbon. Two different routes towards the goal were employed; by studying selected hydrides with carbon as one of its constituents (mainly employing powder diffraction techniques in combination with hydrogen absorption and desorption measurements) and by carefully conducting hydrogen sorption experiments on what was believed to be the most ''promising'' carbon nanomaterial sample. In the latter case, a lot of effort was attributed to characterisations of different carbon nanomaterial containing samples with the aid of electron microscopy. Three different carbon-containing metal hydride systems, Y2C-H, YCoC-H and Y5SiC0.2-H, were examined. A relation between hydrogen occupation and the local arrangement of metal and carbon atoms surrounding the hydrogen sites was established. Several characteristic features of the compounds were noted in addition to solving the structure of the former unknown deuterideY5Si3C0.2D2.0 by the use of direct methods. Several carbon-nanomaterial containing samples were studied by means of transmission electron microscopy and powder diffraction, thus gaining knowledge concerning the structural aspects of nanomaterials. Based on these investigations, a specific sample containing a large amount of open-ended single-wall carbon nanotubes was chosen for subsequent hydrogen storage experiments. The latter experiments revealed moderate hydrogen storage capacities of the nanotubes not exceeding the values obtained for more conventional forms of carbon. These two different routes in investigating the hydrogen storage properties of carbon and carbon containing alloys

Hydrogen storage properties of carbon nanomaterials and carbon containing metal hydrides

Energy Technology Data Exchange (ETDEWEB)

Maehlen, Jan Petter

2003-07-01

The topic of this thesis is structural investigations of carbon containing materials in respect to their hydrogen storage properties. This work was initially triggered by reports of extremely high hydrogen storage capacities of specific carbon nanostructures. It was decided to try to verify and understand the mechanisms in play in case of the existence of such high hydrogen densities in carbon. Two different routes towards the goal were employed; by studying selected hydrides with carbon as one of its constituents (mainly employing powder diffraction techniques in combination with hydrogen absorption and desorption measurements) and by carefully conducting hydrogen sorption experiments on what was believed to be the most ''promising'' carbon nanomaterial sample. In the latter case, a lot of effort was attributed to characterisations of different carbon nanomaterial containing samples with the aid of electron microscopy. Three different carbon-containing metal hydride systems, Y2C-H, YCoC-H and Y5SiC0.2-H, were examined. A relation between hydrogen occupation and the local arrangement of metal and carbon atoms surrounding the hydrogen sites was established. Several characteristic features of the compounds were noted in addition to solving the structure of the former unknown deuterideY5Si3C0.2D2.0 by the use of direct methods. Several carbon-nanomaterial containing samples were studied by means of transmission electron microscopy and powder diffraction, thus gaining knowledge concerning the structural aspects of nanomaterials. Based on these investigations, a specific sample containing a large amount of open-ended single-wall carbon nanotubes was chosen for subsequent hydrogen storage experiments. The latter experiments revealed moderate hydrogen storage capacities of the nanotubes not exceeding the values obtained for more conventional forms of carbon. These two different routes in investigating the hydrogen storage properties of carbon and

Plutonium oxides and uranium and plutonium mixed oxides. Carbon determination

International Nuclear Information System (INIS)

Anon.

Determination of carbon in plutonium oxides and uranium plutonium mixed oxides, suitable for a carbon content between 20 to 3000 ppm. The sample is roasted in oxygen at 1200 0 C, the carbon dioxide produced by combustion is neutralized by barium hydroxide generated automatically by coulometry [fr

Policy options for carbon taxation in the EU

International Nuclear Information System (INIS)

Laurent, Eloi; Le Cacheux, Jacques

2010-06-01

Even though the EU clearly leads the global fight against climate change and despite the additional reduction in emissions due to the global crisis and European recession, the ambitious objectives flagged in the '20-20-20 by 2020' strategy and 'climate-energy package' are probably out of reach if a more resolute and consistent policy of carbon taxation is not rapidly put in place. First, the EU is not as 'virtuous' as it may seem, and shows signs of a 'fatigue' in mitigating climate change; this is explained by the weak incentive structure of current climate institutions, due to both narrow coverage and insufficient stringency of the European 'Emission Trading Scheme' (ETS) - the European 'carbon market'-, and to excessive reliance on emission standards combined with weak energy taxation. Fears of losing competitiveness are a major argument against imposing a higher carbon price on industries, feeding tax competition both within the EU and vis-a-vis the rest of the world. Though not fully satisfactory, the Commission's recent proposal (a revision of the 2003 energy taxation directive introducing floors on national excises based on carbon content) would help solving the intra-EU conundrum. Alternatively, an extension of the EU ETS to households and the transport sector via the 'upstream' inclusion of fossil fuel dealers would also be a feasible solution. In order to answer the 'carbon leakage' argument and to send appropriate price signals to European consumers on extra-EU imports, a border adjustment mechanism - carbon levy or inclusion of importers into the EU ETS - is also necessary. Ultimately though, in order to make sure that economic agents face a uniform carbon price, a generalized carbon tax, in the form of a European 'Carbon Added Tax' (ECAT), would be the most effective instrument in the fight against climate change, as well as the pillar of a thorough tax

In situ mesophase transformation by zirconium chloride in fabrication of carbon/carbon composites

International Nuclear Information System (INIS)

Zhang, Bo; Song, Huaihe; Chen, Xiaohong; Ma, Zhaokun; Yang, Xiaoguang; Xu, Zhenghui

2012-01-01

Carbon/carbon (C/C) composites were prepared using multiple cycle in situ mesophase densification in the presence of zirconium chloride. The mesophase transformation and the performance of C/C composites were investigated in detail. The results show that higher amount of ZrCl 4 and longer soaking time accelerate the condensation of aromatic hydrocarbons. Additionally, the XRD pattern and ash contents show that the ZrCl 4 is retained in the samples and transformed to t-ZrO 2 and m-ZrO 2 after carbonization. In all the composites, the bulk density increases with cycle times, and the flexural strength increases with bulk density. However, a decrease of flexural strength for low density composites was observed when increasing ZrCl 4 concentrations. This tendency is attributed to more ZrO 2 formation in the composites using 20 wt.% ZrCl 4 . Subsequently, these ZrO 2 particles produce interface defects in the matrix which decreases its strength. Attributed to the very low content of ZrO 2 in high density composites, there is no difference between the samples using 13 wt.% and 20 wt.% ZrCl 4 .

dielectric constants of irradiated and carbonated polymers

African Journals Online (AJOL)

user

1985-09-01

Sep 1, 1985 ... These samples, with varying degrees of carbon concentration, are then exposed to infra-red rays from carbon arc lamp; ultraviolet rays from Hg discharge lamp and finally to x- rays. The exposure time is kept at approximately 20 minutes. Figure 1 shows the experimental arrangement for the measurement of.

An easily accessible carbon material derived from carbonization of polyacrylonitrile ultrathin films: ambipolar transport properties and application in a CMOS-like inverter.

Science.gov (United States)

Jiao, Fei; Zhang, Fengjiao; Zang, Yaping; Zou, Ye; Di, Chong'an; Xu, Wei; Zhu, Daoben

2014-03-04

Ultrathin carbon films were prepared by carbonization of a solution processed polyacrylonitrile (PAN) film in a moderate temperature range (500-700 °C). The films displayed balanced hole (0.50 cm(2) V(-1) s(-1)) and electron mobilities (0.20 cm(2) V(-1) s(-1)) under ambient conditions. Spectral characterization revealed that the electrical transport is due to the formation of sp(2) hybridized carbon during the carbonization process. A CMOS-like inverter demonstrated the potential application of this material in the area of carbon electronics, considering its processability and low-cost.

Institute a modest carbon tax to reduce carbon emissions, finance clean energy technology development, cut taxes, and reduce the deficit

Energy Technology Data Exchange (ETDEWEB)

Muro, Mark; Rothwell, Jonathan

2012-11-15

The nation should institute a modest carbon tax in order to help clean up the economy and stabilize the nation’s finances. Specifically, Congress and the president should implement a $20 per ton, steadily increasing carbon excise fee that would discourage carbon dioxide emissions while shifting taxation onto pollution, financing energy efficiency (EE) and clean technology development, and providing opportunities to cut taxes or reduce the deficit. The net effect of these policies would be to curb harmful carbon emissions, improve the nation’s balance sheet, and stimulate job-creation and economic renewal.

The Use of Zeolit and Activated Carbon on Packing System of Corydoras aenus

Directory of Open Access Journals (Sweden)

E. Supriyono

2007-07-01

Full Text Available Problem frequently found by Indonesian exporter in sending ornamental fish including Corydoras aenus to overseas is the low survival rate that caused by decrease in water quality during transportation.  Suitable and efficient packing technology is very needed to send live fish for long time transportation.  Two third of packing plastic volume was filled by oxygen, and Corydoras aenus 20 fish/pack.  Packing plastic was placed into styrofoam and ice was added to maintain at low temperature.  Zeolit and activated carbon was cover up by cloth and then placed into the pack.  Dosage treatment of zeolit and activated carbon was 20 gram zeolit, 15 gram zeolit and 5 gram activated carbon, 10 gram zeolit and 10 gram activated carbon, 5 gram zeolit and 15 gram activated carbon, 20 gram activated carbon, and no added zeolit and no activated carbon as control.  Fish condition was observed every 6 hours, while water quality measurement was performed every 24 hours for 120 hours.  The results of study showed that adding 20 gram zeolit without activated carbon in closed packing system of Corydoras aenus in 20oC could maintained in lower concentration of total nitrogen ammonia and unionized ammonia (NH3, reached of 7.83±0.13 mg/l and 0.046±0.003 mg/l, respectively.  The level of total nitrogen ammonia and unionized ammonia were relatively lower compared to mix of zeolit and activated carbon, and only activated carbon.  Survival rate of fish by this treatment was 100%, higher than other treatment (85-95%. Keywords: zeolit, activated carbon, packing, Corydoras   ABSTRAK Permasalahan yang sering dihadapi oleh para eksportir Indonesia dalam pengiriman ikan hias termasuk Corydoras aenus ke luar negeri adalah rendahnya survival rate diantaranya disebabkan oleh kualitas air yang memburuk selama pengangkutan. Teknologi pengepakan yang tepat dan efisien sangat dibutuhkan dalam rangka pengiriman ikan hidup untuk tempat tujuan yang membutuhkan waktu lama

Carbon storage and recycling in short-rotation energy crops

International Nuclear Information System (INIS)

Ranney, J.W.; Wright, L.L.; Mitchell, C.P.

1991-01-01

Short-rotation energy crops can play a significant role in storing carbon compared to the agricultural land uses they would displace. However, the benefits from these plantations in avoiding further use of fossil fuel and in taking pressure off of native forests for energy uses provides longer term carbon benetfits than the plantation carbon sequestration itself. The fast growth and harvest frequency of plantations tends to limit the amount of above and below-ground carbon storage in them. The primary components of plantation carbon sequestering compared to sustained agricultural practices involve above-ground wood, possible increased soil carbon, litter layer formation, and increased root biomass. On the average, short-rotation plantations in total may increase carbon inventories by about 30 to 40 tonnes per hectare over about a 20- to 56-year period when displacing cropland. This is about doubling in storage over cropland and about one-half the storage in human-impacted forests. The sequestration benefit of wood energy crops over cropland would be negated in about 75 to 100 years by the use of fossil fuels to tend the plantations and handle biomass. Plantation interactions with other land uses and total landscape carbon inventory is important in assessing the relative role plantations play in terrestrial and atmospheric carbon dynamics. It is speculated that plantations, when viewed in this context. could trencrate a global leveling of net carbon emissions for approximately 10 to 20 years

Xanthobacter sp. C20 contains a novel bioconversion pathway for limonene

NARCIS (Netherlands)

Werf, M.J. van der; Keijzer, P.M.; Schaft, P.H. van der

2000-01-01

Xanthobacter sp. C20 was isolated from sediment of the river Rhine using cyclohexane as sole source of carbon and energy. Xanthobacter sp. C20 converted both enantiomers of limonene quantitatively into limonene-8,9-epoxide, a not previously described bioconversion product of limonene. With

Immersion microcalorimetry of a carbon black

International Nuclear Information System (INIS)

Mendelbaum, Georges

1966-01-01

This research thesis first reports a detailed bibliographical study on various topics (fabrication of carbon black, oxidation, immersion heat, adsorptions, main existing theories, and thermodynamics) and then the development of immersion and adsorption microcalorimetry apparatuses aimed at studying the surface of a carbon black and the influence of the oxidation of this carbon black on the adsorption of polar and non-polar solvents. Immersion heats of a raw or oxidised carbon black have been measured in water, in cyclohexane and in methanol. The adsorption of methanol at 20 C and that of nitrogen at -196 C have also been measured. The author outlines that degassing conditions had to be taken into account before performing measurements [fr

20th-Century Industrial Black Carbon Emissions Altered Arctic Climate Forcing

OpenAIRE

McConnell, J. R; Edwards, R.; Kok, G. L; Flanner, M. G; Zender, C. S; Saltzman, E. S; Banta, J. R; Pasteris, D. R; Carter, M. M; Kahl, J. D. W

2007-01-01

Black carbon (BC) from biomass and fossil fuel combustion alters chemical and physical properties of the atmosphere and snow albedo, yet little is known about its emission or deposition histories. Measurements of BC, vanillic acid, and non–sea-salt sulfur in ice cores indicate that sources and concentrations of BC in Greenland precipitation varied greatly since 1788 as a result of boreal forest fires and industrial activities. Beginning about 1850, industrial emissions resulted in a sevenfold...

Forest and wood products role in carbon sequestration

Energy Technology Data Exchange (ETDEWEB)

Sampson, R.N.

1997-12-31

An evaluation of the use of U.S. forests and forest products for carbon emission mitigation is presented. The current role of forests in carbon sequestration is described in terms of regional differences and forest management techniques. The potential for increasing carbon storage by converting marginal crop and pasture land, increasing timberland growth, reducing wildfire losses, and changing timber harvest methods is examined. Post-harvest carbon flows, environmental impacts of wood products, biomass energy crops, and increased use of energy-conserving trees are reviewed for their potential in reducing or offsetting carbon emissions. It is estimated that these techniques could offset 20 to 40 percent of the carbon emitted annually in the U.S. 39 refs., 5 tabs.

An approach to include soil carbon changes in life cycle assessments

DEFF Research Database (Denmark)

Petersen, Bjorn Molt; Knudsen, Marie Trydeman; Hermansen, John Erik

2013-01-01

to estimate carbon sequestration to be included in LCA is suggested and applied to two examples where the inclusion of carbon sequestration is especially relevant: 1) Bioenergy: removal of straw from a Danish soil for energy purposes and 2) Organic versus conventional farming: comparative study of soybean...... comparable to the IPCC 2006 tier I approach in a time perspective of 20 year, where after the suggested methodology showed a continued soil carbon change toward a new steady state. The suggested method estimated a carbon sequestration for the first example when storing straw in the soil instead of using...... it for bioenergy of 54, 97 and 213 kg C t(-1) straw C in a 200, 100 and 20 years perspective, respectively. For the conversion from conventional to organic soybean production, a difference of 32, 60 or 143 kg soil C ha(-1) yr(-1) in a 200,100 or 20 years perspective, respectively was found. The study indicated...

Interaction cross-sections and matter radii of A = 20 isobars

International Nuclear Information System (INIS)

Chulkov, L.; Bochkarev, O.; Geissel, H.; Golovkov, M.; Janas, Z.; Keller, H.; Kobayashi, T.; Muenzenberg, G.; Nickel, F.; Ogloblin, A.; Patra, S.; Piechaczek, A.; Roeckl, E.; Schwab, W.; Suemmerer, K.; Suzuki, T.; Tanihata, I.; Yoshida, K.

1995-11-01

High-energy interaction cross-sections of A=20 nuclei ( 20 N, 20 O, 20 F, 20 Ne, 20 Na, 20 Mg) on carbon were measured with accuracies of ∼1%. The nuclear matter rms radii derived from the measured cross-sections show an irregular dependence on isospin projection. The largest difference in radii, which amounts to approximately 0.2 fm, has been obtained for the mirror nuclei 20 O and 20 Mg. The influenc of nuclear deformation and binding energy on the radii is discussed. By evaluating the difference in rms radii of neutron and proton distributions, evidence has been found for the existence of a proton skin for 20 Mg and of a neutron skin for 20 N. (orig.)

Massive carbon addition to an organic-rich Andosol increased the subsoil but not the topsoil carbon stock

Science.gov (United States)

Zieger, Antonia; Kaiser, Klaus; Ríos Guayasamín, Pedro; Kaupenjohann, Martin

2018-05-01

Andosols are among the most carbon-rich soils, with an average of 254 Mg ha-1 organic carbon (OC) in the upper 100 cm. A current theory proposes an upper limit for OC stocks independent of increasing carbon input, because of finite binding capacities of the soil mineral phase. We tested the possible limits in OC stocks for Andosols with already large OC concentrations and stocks (212 g kg-1 in the first horizon, 301 Mg ha-1 in the upper 100 cm). The soils received large inputs of 1800 Mg OC ha-1 as sawdust within a time period of 20 years. Adjacent soils without sawdust application served as controls. We determined total OC stocks as well as the storage forms of organic matter (OM) of five horizons down to 100 cm depth. Storage forms considered were pyrogenic carbon, OM of 2.0 g cm-3. The two fractions > 1.6 g cm-3 were also analysed for aluminium-organic matter complexes (Al-OM complexes) and imogolite-type phases using ammonium-oxalate-oxalic-acid extraction and X-ray diffraction (XRD). Pyrogenic organic carbon represented only up to 5 wt % of OC, and thus contributed little to soil OM. In the two topsoil horizons, the fraction between 1.6 and 2.0 g cm-3 had 65-86 wt % of bulk soil OC and was dominated by Al-OM complexes. In deeper horizons, the fraction > 2.0 g cm-3 contained 80-97 wt % of the bulk soil's total OC and was characterized by a mixture of Al-OM complexes and imogolite-type phases, with proportions of imogolite-type phases increasing with depth. In response to the sawdust application, only the OC stock at 25-50 cm depth increased significantly (α = 0.05, 1 - β = 0.8). The increase was entirely due to increased OC in the two fractions > 1.6 g cm-3. However, there was no significant increase in the total OC stocks within the upper 100 cm. The results suggest that long-term large OC inputs cannot be taken up by the obviously OC-saturated topsoil but induce downward migration and gradually increasing storage of OC in subsurface soil layers. The small

Biological and ecological responses to carbon-based nanomaterials

Science.gov (United States)

Ratnikova, Tatsiana A.

This dissertation examines the biological and ecological responses to carbon nanoparticles, a major class of nanomaterials which have been mass produced and extensively studied for their rich physical properties and commercial values. Chapter I of this dissertation offers a comprehensive review on the structures, properties, applications, and implications of carbon nanomaterials, especially related to the perspectives of biological and ecosystems. Given that there are many types of carbon nanomaterials available, this chapter is focused on three major types of carbon-based nanomaterials only, namely, fullerenes, single walled and multi-walled carbon nanotubes. On the whole organism level, specifically, Chapter II presents a first study on the fate of fullerenes and multiwalled carbon nanotubes in rice plants, which was facilitated by the self assembly of these nanomaterials with NOM. The aspects of fullerene uptake, translocation, biodistribution, and generational transfer in the plants were examined and quantified using bright field and electron microscopy, FT-Raman, and FTIR spectroscopy. The uptake and transport of fullerene in the plant vascular system were attributed to water transpiration, convection, capillary force, and the fullerene concentration gradient from the roots to the leaves of the plants. On the cellular level, Chapter III documents the differential uptake of hydrophilic C60(OH)20 vs. amphiphilic C70-NOM complex in Allium cepa plant cells and HT-29 colon carcinoma cells. This study was conducted using a plant cell viability assay, and complemented by bright field, fluorescence and electron microscopy imaging. In particular, C60(OH)20 and C70-NOM showed contrasting uptake in both the plant and mammalian cells, due to their significant differences in physicochemistry and the presence of an extra hydrophobic plant cell wall in the plant cells. Consequently, C60(OH)20 was found to induce toxicity in Allium cepa cells but not in HT-29 cells, while C70

Carbon taxation reform in the European Union. The options involved

International Nuclear Information System (INIS)

Laurent, Eloi; Le Cacheux, Jacques

2011-01-01

Even though the EU clearly leads the global fight against climate change and despite the additional reduction in emissions due to the global crisis and European recession, the ambitious objectives flagged in the '20-20-20 by 2020' strategy and 'climate-energy package' may be out of reach if a more resolute and consistent policy of carbon taxation is not rapidly put in place in the EU. In this paper, we detail and discuss the different options available for such European carbon taxation. Initially published in 'Revue de l'OFCE' No. 116

Quantitative analysis of carbon in plutonium

International Nuclear Information System (INIS)

Lefevre, Chantal.

1979-11-01

The aim of this study is to develop a method for the determination of carbon traces (20 to 400 ppm) in plutonium. The development of a carbon in plutonium standard is described, then the content of this substance is determined and its validity as a standard shown by analysis in two different ways. In the first method used, reaction of the metal with sulphur and determination of carbon as carbon sulphide, the following parameters were studied: influence of excess reagent, surface growth of samples in contact with sulphur, temperature and reaction time. The results obtained are in agreement with those obtained by the conventional method of carbon determination, combustion in oxygen and measurement of carbon in the form of carbon dioxide. Owing to the presence of this standard we were then able to study the different parameters involved in plutonium combustion so that the reaction can be made complete: temperature reached during combustion, role of flux, metal surface in contact with oxygen and finally method of cleaning plutonium samples [fr

Achieving high performance in intermediate temperature direct carbon fuel cells with renewable carbon as a fuel source

International Nuclear Information System (INIS)

Hao, Wenbin; He, Xiaojin; Mi, Yongli

2014-01-01

Highlights: • Bamboo fiber and waste paper were pyrolyzed to generate bamboo carbon and waste paper carbon as anode fuels of IT-DCFC. • Superior cell performance was achieved with the waste paper carbon. • The results suggested the high performance was due to the highest thermal reactivity and the catalytic inherent impurities. • Calcite and kaolinite as inherent impurities favored the thermal decomposition and the electrooxidation of carbon. - Abstract: Three kinds of carbon sources obtained from carbon black, bamboo fiber and waste paper were investigated as anode fuels in an intermediate temperature direct carbon fuel cell. The carbon sources were characterized with X-ray photoelectron spectroscopy, thermal gravimetric analysis, etc. The results indicated that the waste paper carbon was more abundant in calcite and kaolinite, and showed higher thermal reactivity in the intermediate temperature range compared with the other two carbon sources. The cell performance was tested at 650 °C in a hybrid single cell, using Sm 0.20 Ce 0.80 O 2−x as the electrolyte. As a result, the cell fed with waste paper carbon showed the highest performance among the three carbon sources, with a peak power density of 225 mW cm −2 . The results indicated that its inherent impurities, such as calcite and kaolinite, might favor the thermal gasification of renewable carbon sources, which resulted in the enhanced performance of the intermediate temperature direct carbon fuel cell

Effect of membrane on carbonation and carbon dioxide uptake of Chlorella sp.

Directory of Open Access Journals (Sweden)

Suali Emma

2017-01-01

Full Text Available Recent studies showed that as low as 5% CO2 increased microalgae growth. However, common bioreactor operation resulted in low carbonation due to poor CO2 mass transfer and this inhibited CO2 uptake of microalgae. Although bubbling increases mass transfer of CO2-O2 exchange, preserving high dissolved CO2 remains the most challenging of microalgae cultivation in bioreactor. In order to increase high dissolved CO2 and CO2-O2 exchange, this study employed two types of membrane; hollow-fibre membrane for carbonation and hydrophobic membrane for deoxygenation. It was found that membrane increased carbonation from 20 % to 75 % when operated at control CO2 concentration. The hollow-fibre membrane capable of creating as small as 2 mm bubble which effective for high carbonation. At the same time, itincreased CO2 uptake up to 85% in bioreactor. The hydrophobic membrane removed 43% O2 from the bioreactor. Both membranes increased mass transfer of CO2-O2 exchange in bioreactor which stimulated microalgae growth.

Carbon dioxide production in animal houses

DEFF Research Database (Denmark)

Pedersen, Søren; Blanes-Vidal, Victoria; Joergensen, H.

2008-01-01

cellars are emptied regularly in a four weeks interval. Due to a high and variable carbon dioxide production in deep straw litter houses and houses with indoor storage of manure longer than four weeks, we do not recommend to calculate the ventilation flow based on the carbon dioxide concentration......This article deals with carbon dioxide production from farm animals; more specifically, it addresses the possibilities of using the measured carbon dioxide concentration in animal houses as basis for estimation of ventilation flow (as the ventilation flow is a key parameter of aerial emissions from...... animal houses). The investigations include measurements in respiration chambers and in animal houses, mainly for growing pigs and broilers. Over the last decade a fixed carbon dioxide production of 185 litres per hour per heat production unit, hpu (i.e. 1000 W of the total animal heat production at 20o...

The effect of brushing with nano calcium carbonate and calcium carbonate toothpaste on the surface roughness of nano-ionomer

Science.gov (United States)

Anisja, D. H.; Indrani, D. J.; Herda, E.

2017-08-01

Nanotechnology developments in dentistry have resulted in the development of nano-ionomer, a new restorative material. The surface roughness of restorative materials can increase bacteria adhesion and lead to poor oral hygiene. Abrasive agents in toothpaste can alter tooth and restorative material surfaces. The aim of this study is to identify the effect of brushing with nano calcium carbonate, and calcium carbonate toothpaste on surface roughness of nano-ionomer. Eighteen nano-ionomer specimens were brushed with Aquabidest (doubledistilled water), nano calcium carbonate and calcium carbonate toothpaste. Brushing lasted 30 minutes, and the roughness value (Ra) was measured after each 10 minute segment using a surface roughness tester. The data was analyzed using repeated ANOVA and one-way ANOVA test. The value of nano-ionomer surface roughness increased significantly (p<0.05) after 20 minutes of brushing with the nano calcium carbonate toothpaste. Brushing with calcium carbonate toothpaste leaves nano-ionomer surfaces more rugged than brushing with nano calcium carbonate toothpaste.

[Carbon fiber-reinforced plastics as implant materials].

Science.gov (United States)

Bader, R; Steinhauser, E; Rechl, H; Siebels, W; Mittelmeier, W; Gradinger, R

2003-01-01

Carbon fiber-reinforced plastics have been used clinically as an implant material for different applications for over 20 years.A review of technical basics of the composite materials (carbon fibers and matrix systems), fields of application,advantages (e.g., postoperative visualization without distortion in computed and magnetic resonance tomography), and disadvantages with use as an implant material is given. The question of the biocompatibility of carbon fiber-reinforced plastics is discussed on the basis of experimental and clinical studies. Selected implant systems made of carbon composite materials for treatments in orthopedic surgery such as joint replacement, tumor surgery, and spinal operations are presented and assessed. Present applications for carbon fiber reinforced plastics are seen in the field of spinal surgery, both as cages for interbody fusion and vertebral body replacement.

The physical nature and manufacture of activated carbon

Energy Technology Data Exchange (ETDEWEB)

McDougall, G.J. (NCP, Bedfordview (South Africa))

1991-04-01

After defining activated carbon, the author describes its structure and outlines the physical characteristics distinguishing one type of activated carbon from another. The adsorptive properties of these carbons, the raw materials used, and the manufacturing processes - chemical activation, and physical or thermal activation - are eoutlined. The high-temperature thermal route (which is the most important for the products employed in gold recovery) using coconut shells or coals as the raw material is then discussed in some detail. 20 refs., 11 figs., 2 tabs.

The distributional implications of a carbon tax in Ireland

International Nuclear Information System (INIS)

Callan, Tim; Lyons, Sean; Scott, Susan; Tol, Richard S.J.; Verde, Stefano

2009-01-01

We study the effects of carbon tax and revenue recycling across the income distribution in the Republic of Ireland. In absolute terms, a carbon tax of EUR20/tCO 2 would cost the poorest households less than EUR3/week and the richest households more than EUR4/week. A carbon tax is regressive, therefore. However, if the tax revenue is used to increase social benefits and tax credits, households across the income distribution can be made better off without exhausting the total carbon tax revenue. (author)

Raman Spectroscopy and Electrochemical Investigations of Pt Electrocatalyst Supported on Carbon Prepared through Plasma Pyrolysis of Natural Gas

Directory of Open Access Journals (Sweden)

Tereza Cristina Santos Evangelista

2015-01-01

Full Text Available Physicochemical and electrochemical characterisations of Pt-based electrocatalysts supported on carbon (Vulcan carbon, C1, and carbon produced by plasma pyrolysis of natural gas, C2 toward ethanol electrooxidation were investigated. The Pt20/C180 and Pt20/C280 electrocatalysts were prepared by thermal decomposition of polymeric precursors at 350°C. The electrochemical and physicochemical characterisations of the electrocatalysts were performed by means of X-ray diffraction (XRD, transmission electron microscope (TEM, Raman scattering, cyclic voltammetry, and chronoamperometry tests. The XRD results show that the Pt-based electrocatalysts present platinum metallic which is face-centered cubic structure. The results indicate that the Pt20/C180 electrocatalyst has a smaller particle size (10.1–6.9 nm compared with the Pt20/C280 electrocatalyst; however, the Pt20/C280 particle sizes are similar (12.8–10.4 nm and almost independent of the reflection planes, which suggests that the Pt crystallites grow with a radial shape. Raman results reveal that both Vulcan carbon and plasma carbon are graphite-like materials consisting mostly of sp2 carbon. Cyclic voltammetry and chronoamperometry data obtained in this study indicate that the deposition of Pt on plasma carbon increases its electrocatalytic activity toward ethanol oxidation reaction.

Photoconductivity of Activated Carbon Fibers

Science.gov (United States)

Kuriyama, K.; Dresselhaus, M. S.

1990-08-01

The photoconductivity is measured on a high-surface-area disordered carbon material, namely activated carbon fibers, to investigate their electronic properties. Measurements of decay time, recombination kinetics and temperature dependence of the photoconductivity generally reflect the electronic properties of a material. The material studied in this paper is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000--2000m{sup 2}/g. Our preliminary thermopower measurements suggest that this carbon material is a p-type semiconductor with an amorphous-like microstructure. The intrinsic electrical conductivity, on the order of 20S/cm at room temperature, increases with increasing temperature in the range 30--290K. In contrast with the intrinsic conductivity, the photoconductivity in vacuum decreases with increasing temperature. The recombination kinetics changes from a monomolecular process at room temperature to a biomolecular process at low temperatures. The observed decay time of the photoconductivity is {approx equal}0.3sec. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The intrinsic carrier density and the activation energy for conduction are estimated to be {approx equal}10{sup 21}/cm{sup 3} and {approx equal}20meV, respectively. The majority of the induced photocarriers and of the intrinsic carriers are trapped, resulting in the long decay time of the photoconductivity and the positive temperature dependence of the conductivity.

Removal of cadmium and lead from water by activated carbon

International Nuclear Information System (INIS)

Abdel-Shafy, H.I.; Abdel-Sabour, M.F.; El-Gamal, I.M.; Abo-El-Wafa, O.

1989-01-01

Adsorption of cadmium and lead from water by carbon was studied using powdered or granular carbon. The studied water artificially contaminated by cadmium and lead amounting to 1 mg/dm 3 each. Batch as well as continuous system were carried out. The batch system was used to determine the time to maintain equilibrium followed by adsorption isotherm. Results obtained by using the powered carbon were found to match with Freundlich's equation where 1/n was 2.12 and 2.096 for Cd and Pb, respectively. Corresponding constants (K) were 4.2·10 -2 and 76.0·10 -2 . The amount of powdered activated carbon required to reduce residual Cd and Pb concentration to 0.01 mg/dm 3 for each are 26.98 and 2.86 mg, respectively. Similar batch system study was carried out for the granular carbon. When granular carbon was used in a continuous system, two different contact times, namely 10 to 20 min were examined. The results obtained showed that increasing the contact time from 10 to 20 min increases the metal to carbon removal efficiency. The overall results indicated that the breakthrough point for either Cd or Pb is the reverse of their adsorption as indicated by K value. (author). 22 refs, 10 figs, 7 tabs

McSUB V2.0, an upgraded version of the Monte Carlo library McSUB with inclusion of weight factors

International Nuclear Information System (INIS)

Hoek, M.

1991-02-01

The Monte Carlo library McSUB, which was described in an earlier report, has been upgraded to McSUB V2.0. McSUB V2.0 can be used to simulate the neutron transport in a medium which is a mixture of hydrogen and carbon or a mixture of deuterium and carbon. The implemented neutron energy interval is 0.1 - 20 MeV and the library can be used to simulate elastic and inelastic scattering. The inelastic scattering with carbon takes into account the four lowest excited states of the carbon nucleus. McSUB V2.0 is downward compatible with McSUB expect for the layout of the parameter file which now contains more variables. The major upgrade has been the inclusion of routines using weight factors which has speeded up the old version considerably. McSUB V2.0 also makes a biasing technique possible. It is now possible to e.g. let a neutron scatter with a selected nucleus followed by a biased scattering direction. (au)

Nanoporous carbon for electrochemical capacitors.

Energy Technology Data Exchange (ETDEWEB)

Siegal, Michael P.; Bunker, Bruce Conrad; Limmer, Steven J.; Yelton, William Graham

2010-05-01

Nanoporous carbon (NPC) is a purely graphitic material with highly controlled densities ranging from less than 0.1 to 2.0 g/cm3, grown via pulsed-laser deposition. Decreasing the density of NPC increases the interplanar spacing between graphene-sheet fragments. This ability to tune the interplanar spacing makes NPC an ideal model system to study the behavior of carbon electrodes in electrochemical capacitors and batteries. We examine the capacitance of NPC films in alkaline and acidic electrolytes, and measure specific capacitances as high as 242 F/g.

Nanoporous carbon for electrochemical capacitors.

Energy Technology Data Exchange (ETDEWEB)

Overmyer, Donald L.; Siegal, Michael P.; Bunker, Bruce Conrad; Limmer, Steven J.; Yelton, William Graham

2010-04-01

Nanoporous carbon (NPC) is a purely graphitic material with highly controlled densities ranging from less than 0.1 to 2.0 g/cm3, grown via pulsed-laser deposition. Decreasing the density of NPC increases the interplanar spacing between graphene-sheet fragments. This ability to tune the interplanar spacing makes NPC an ideal model system to study the behavior of carbon electrodes in electrochemical capacitors and batteries. We examine the capacitance of NPC films in alkaline and acidic electrolytes, and measure specific capacitances as high as 242 F/g.

Accounting for forest carbon pool dynamics in product carbon footprints: Challenges and opportunities

International Nuclear Information System (INIS)

Newell, Joshua P.; Vos, Robert O.

2012-01-01

Modification and loss of forests due to natural and anthropogenic disturbance contribute an estimated 20% of annual greenhouse gas (GHG) emissions worldwide. Although forest carbon pool modeling rarely suggests a ‘carbon neutral’ flux profile, the life cycle assessment community and associated product carbon footprint protocols have struggled to account for the GHG emissions associated with forestry, specifically, and land use generally. Principally, this is due to underdeveloped linkages between life cycle inventory (LCI) modeling for wood and forest carbon modeling for a full range of forest types and harvest practices, as well as a lack of transparency in globalized forest supply chains. In this paper, through a comparative study of U.S. and Chinese coated freesheet paper, we develop the initial foundations for a methodology that rescales IPCC methods from the national to the product level, with reference to the approaches in three international product carbon footprint protocols. Due to differences in geographic origin of the wood fiber, the results for two scenarios are highly divergent. This suggests that both wood LCI models and the protocols need further development to capture the range of spatial and temporal dimensions for supply chains (and the associated land use change and modification) for specific product systems. The paper concludes by outlining opportunities to measure and reduce uncertainty in accounting for net emissions of biogenic carbon from forestland, where timber is harvested for consumer products. - Highlights: ► Typical life cycle assessment practice for consumer products often excludes significant land use change emissions when estimating carbon footprints. ► The article provides a methodology to rescale IPCC guidelines for product-level carbon footprints. ► Life cycle inventories and product carbon footprint protocols need more comprehensive land use-related accounting. ► Interdisciplinary collaboration linking the LCA and

A comparative study of modern carbonate mud in reefs and carbonate platforms: Mostly biogenic, some precipitated

Science.gov (United States)

Gischler, Eberhard; Dietrich, Sarah; Harris, Daniel; Webster, Jody M.; Ginsburg, Robert N.

2013-06-01

Carbonate mud from reefs and carbonate platforms in six locations of the Atlantic, Indian, and Pacific Oceans (Belize, Bahamas, Florida, the Maldives, French Polynesia, Great Barrier Reef) was systematically and quantitatively analyzed with regard to texture, composition, mineralogy, and geochemistry. Mud composition shows considerable variability, however, the data supports the contention that these muds are largely derived from the breakdown of skeletal grains and codiacean algae. Only mud from the Bahamas and northern Belize, areas which are characterized by common whitings, is interpreted to be mainly inorganically precipitated. Three grain-size fractions (63-20 μm, 20-4 μm, aragonite needles, nanograins, and coccoliths. Coccoliths are common in deeper lagoonal settings of the open ocean settings (Maldives, French Polynesia). The geochemistry of the aragonite contents and strontium concentrations, suggesting physico-chemical precipitation. The northern Belize and Great Barrier Reef samples show the highest magnesium calcite values and, accordingly, produced the lowest aragonite and strontium measurements. The high-magnesium calcite portion of the northern Belize mud is either precipitated or due to abundant micritized skeletal grains (e.g., foraminifera): more studies are needed to verify the origin. In the case of the Great Barrier Reef sample, coralline algae appear to be the source of abundant high-magnesium calcite. This study emphasizes that from a global perspective, modern muds in reefs and carbonate platforms exhibit different compositions but are in many cases biologically derived. Even though the composition of modern carbonate muds varies among the six locations investigated, they may serve as analogs for the formation of muds in Cenozoic and Mesozoic reefs and carbonate platforms. Limitations of the interpretation of carbonate-mud origin include the difficulty of identifying, quantifying, and analyzing small grains, the ease with which small

Influence of land use changes on soil carbon stock and soil carbon erosion in a Mediterranean catchment

Energy Technology Data Exchange (ETDEWEB)

Boix-Fayos, C.; Martinez-Mena, M.; Vente, J. de; Albaladejo, J.

2009-07-01

The effect of changing land uses on the organic soil carbon (C) stock and the soil C transported by water erosion and buried in depositions wedges behring check-dams was estimated in a Mediterranean catchment in SE Spin. the 57% decrease in agricultural areas and 1.5-fold increase of the total forest cover between 1956 and 1997 induced an accumulation rate of total organic carbon (TOC) in the soil of 10.73 g m{sup -}2 yr{sup -}1. The mineral-associated organic carbon (MOC) represented the 70% of the soil carbon pool, the particulate organic carbon (POC) represented a 30% of the soil carbon pool. The average sediments/soil enrichment ratio at the sub catchment scale (8-125 ha) was 0.59{+-}0.43 g kg{sup -}1. Eroded soil C accounted for between 2% to 78% of the soil c stock in the first 5 cm of the soil in the subcatchments. the C erosion rate varied between 0.008 and 0.2 t ha{sup -}1 yr{sup -}1. (Author) 20 refs.

Influence of land use changes on soil carbon stock and soil carbon erosion in a Mediterranean catchment

International Nuclear Information System (INIS)

Boix-Fayos, C.; Martinez-Mena, M.; Vente, J. de; Albaladejo, J.

2009-01-01

The effect of changing land uses on the organic soil carbon (C) stock and the soil C transported by water erosion and buried in depositions wedges behring check-dams was estimated in a Mediterranean catchment in SE Spin. the 57% decrease in agricultural areas and 1.5-fold increase of the total forest cover between 1956 and 1997 induced an accumulation rate of total organic carbon (TOC) in the soil of 10.73 g m - 2 yr - 1. The mineral-associated organic carbon (MOC) represented the 70% of the soil carbon pool, the particulate organic carbon (POC) represented a 30% of the soil carbon pool. The average sediments/soil enrichment ratio at the sub catchment scale (8-125 ha) was 0.59±0.43 g kg - 1. Eroded soil C accounted for between 2% to 78% of the soil c stock in the first 5 cm of the soil in the subcatchments. the C erosion rate varied between 0.008 and 0.2 t ha - 1 yr - 1. (Author) 20 refs.

Evaluation of various carbon blacks and dispersing agents for use in the preparation of uranium microspheres with carbon

Science.gov (United States)

Hunt, R. D.; Johnson, J. A.; Collins, J. L.; McMurray, J. W.; Reif, T. J.; Brown, D. R.

2018-01-01

A comparison study on carbon blacks and dispersing agents was performed to determine their impacts on the final properties of uranium fuel kernels with carbon. The main target compositions in this internal gelation study were 10 and 20 mol % uranium dicarbide (UC2), which is UC1.86, with the balance uranium dioxide. After heat treatment at 1900 K in flowing carbon monoxide in argon for 12 h, the density of the kernels produced using a X-energy proprietary carbon suspension, which is commercially available, ranged from 96% to 100% of theoretical density (TD), with full conversion of UC to UC2 at both carbon concentrations. However, higher carbon concentrations such as a 2.5 mol ratio of carbon to uranium in the feed solutions failed to produce gel spheres with the proprietary carbon suspension. The kernels using our former baseline of Mogul L carbon black and Tamol SN were 90-92% of TD with full conversion of UC to UC2 at a variety of carbon levels. Raven 5000 carbon black and Tamol SN were used to produce 10 mol % UC2 kernels with 95% of TD. However, an increase in the Raven 5000 concentration led to a kernel density below 90% of TD. Raven 3500 carbon black and Tamol SN were used to make very dense kernels without complete conversion to UC2. The selection of the carbon black and dispersing agent is highly dependent on the desired final properties of the target kernels.

Soil carbon sequestration due to post-Soviet cropland abandonment: estimates from a large-scale soil organic carbon field inventory.

Science.gov (United States)

Wertebach, Tim-Martin; Hölzel, Norbert; Kämpf, Immo; Yurtaev, Andrey; Tupitsin, Sergey; Kiehl, Kathrin; Kamp, Johannes; Kleinebecker, Till

2017-09-01

The break-up of the Soviet Union in 1991 triggered cropland abandonment on a continental scale, which in turn led to carbon accumulation on abandoned land across Eurasia. Previous studies have estimated carbon accumulation rates across Russia based on large-scale modelling. Studies that assess carbon sequestration on abandoned land based on robust field sampling are rare. We investigated soil organic carbon (SOC) stocks using a randomized sampling design along a climatic gradient from forest steppe to Sub-Taiga in Western Siberia (Tyumen Province). In total, SOC contents were sampled on 470 plots across different soil and land-use types. The effect of land use on changes in SOC stock was evaluated, and carbon sequestration rates were calculated for different age stages of abandoned cropland. While land-use type had an effect on carbon accumulation in the topsoil (0-5 cm), no independent land-use effects were found for deeper SOC stocks. Topsoil carbon stocks of grasslands and forests were significantly higher than those of soils managed for crops and under abandoned cropland. SOC increased significantly with time since abandonment. The average carbon sequestration rate for soils of abandoned cropland was 0.66 Mg C ha -1  yr -1 (1-20 years old, 0-5 cm soil depth), which is at the lower end of published estimates for Russia and Siberia. There was a tendency towards SOC saturation on abandoned land as sequestration rates were much higher for recently abandoned (1-10 years old, 1.04 Mg C ha -1  yr -1 ) compared to earlier abandoned crop fields (11-20 years old, 0.26 Mg C ha -1  yr -1 ). Our study confirms the global significance of abandoned cropland in Russia for carbon sequestration. Our findings also suggest that robust regional surveys based on a large number of samples advance model-based continent-wide SOC prediction. © 2017 John Wiley & Sons Ltd.

Method for creating high carbon content products from biomass oil

Science.gov (United States)

Parker, Reginald; Seames, Wayne

2012-12-18

In a method for producing high carbon content products from biomass, a biomass oil is added to a cracking reactor vessel. The biomass oil is heated to a temperature ranging from about 100.degree. C. to about 800.degree. C. at a pressure ranging from about vacuum conditions to about 20,700 kPa for a time sufficient to crack the biomass oil. Tar is separated from the cracked biomass oil. The tar is heated to a temperature ranging from about 200.degree. C. to about 1500.degree. C. at a pressure ranging from about vacuum conditions to about 20,700 kPa for a time sufficient to reduce the tar to a high carbon content product containing at least about 50% carbon by weight.

Protect Yourself from Carbon Monoxide Poisoning

Centers for Disease Control (CDC) Podcasts

2007-11-20

Learn about carbon monoxide - a colorless, odorless gas - and how to protect yourself and your family.  Created: 11/20/2007 by CDC National Center for Environmental Health.   Date Released: 12/4/2007.

Sequestration of Soil Carbon as Secondary Carbonates (Invited)

Science.gov (United States)

Lal, R.

2013-12-01

Rattan Lal Carbon Management and Sequestration Center The Ohio State University Columbus, OH 43210 USA Abstract World soils, the major carbon (C) reservoir among the terrestrial pools, contain soil organic C (SOC) and soil inorganic C (SIC). The SIC pool is predominant in soils of arid and semi-arid regions. These regions cover a land area of about 4.9x109 ha. The SIC pool in soils containing calcic and petrocalcic horizons is estimated at about 695-748 Pg (Pg = 1015 g = 1 gigaton) to 1-m depth. There are two types of carbonates. Lithogenic or primary carbonates are formed from weathering of carbonaceous rocks. Pedogenic or secondary carbonates are formed by dissolution of CO2 in the soil air to form carbonic acid and precipitation as carbonates of Ca+2 or Mg+2. It is the availability of Ca+2 or Mg+2 from outside the ecosystem that is essential to sequester atmospheric CO2. Common among outside sources of Ca+2 or Mg+2 are irrigation water, aerial deposition, sea breeze, fertilizers, manure and other amendments. The decomposition of SOC and root respiration may increase the partial pressure of CO2 in the soil air and lead to the formation of HCO_3^- upon dissolution in H20. Precipitation of secondary carbonates may result from decreased partial pressure of CO2 in the sub-soil, increased concentration of Ca+2, Mg+2 and HCO_3^- in soil solution, and decreased soil moisture content by evapotranspiration. Transport of bicarbonates in irrigated soils and subsequent precipitation above the ground water (calcrete), activity of termites and other soil fauna, and management of urban soils lead to formation of secondary carbonates. On a geologic time scale, weathering of silicate minerals and transport of the by-products into the ocean is a geological process of sequestration of atmospheric CO2. Factors affecting formation of secondary carbonates include land use, and soil and crop management including application of biosolids, irrigation and the quality of irrigation water

Nano-micro carbon spheres anchored on porous carbon derived from dual-biomass as high rate performance supercapacitor electrodes

Science.gov (United States)

Liu, Shaobo; Zhao, Yang; Zhang, Baihui; Xia, Hui; Zhou, Jianfei; Xie, Wenke; Li, Hongjian

2018-03-01

Hierarchical nano-micro carbon spheres@rice straw-derived porous carbon composites are successfully synthesized by the in situ decoration of the porous carbon with carbon spheres from glucose under the assistance of cetyltrimethyl ammonium bromide micelles and further activated by KOH. The scanning electron microscope images clearly show the carbon spheres disperse homogeneously and orderly onto the surface and in the inner macropores of the porous carbon. The diameter of the carbon spheres varies from 475 nm to 1.6 μm, which can be easily controlled by introducing extra inducing agent. The optimal composites exhibit a large specific surface area (1122 m2 g-1), rich content of oxygen (14.2 wt %), and tunable hierarchical porous structure. When used as supercapacitor electrodes, the novel composites with abundant fruits present a high specific capacitance of 337 F g-1 at 1 A g-1, excellent rate retention of 83% from 1 to 20 A g-1 and a good cycling stability with 96% capacitance retention after 10000 cycles. In this strategy, the thought of shared ion-buffering reservoirs is proposed and the mutual promotion effects between the carbon spheres and porous carbon in the composites are also practically demonstrated to contribute the enhanced electrochemical performances.

Electrochemical parameters of ethamsylate at multi-walled carbon nanotube modified glassy carbon electrodes.

Science.gov (United States)

Wang, Sheng-Fu; Xu, Qiao

2007-05-01

In this paper, some electrochemical parameters of ethamsylate at a multi-walled carbon nanotube modified glassy carbon electrode, such as the charge number, exchange current density, standard heterogeneous rate constant and diffusion coefficient, were measured by cyclic voltammetry, chronoamperometry and chronocoulometry. The modified electrode exhibits good promotion of the electrochemical reaction of ethamsylate and increases the standard heterogeneous rate constant of ethamsylate greatly. The differential pulse voltammetry responses of ethamsylate were linearly dependent on its concentrations in a range from 2.0 x 10(-6) to 6.0 x 10(-5) mol L(-1), with a detection limit of 4.0 x 10(-7) mol L(-1).

Changes in physical properties and organic carbon of a Kandiudox fertilized with manure

Directory of Open Access Journals (Sweden)

Andréia Patricia Andrade

2016-05-01

Full Text Available ABSTRACT: Successive applications of pig slurry and poultry manure can improve the soil structure, according to the land use conditions and amounts applied. This study evaluated the effect of manure fertilization on the physical properties and organic carbon of a Rhodic Kandiudox. Treatments included land use and management and time of pig slurry and poultry litter application, namely: native forest (NF; yerba mate after 20 years of animal waste application (YM20; pasture after 15 years of application (P15; grassland after 20 years of manuring (PP20; grassland after 3 years of manuring (P3; pasture without application (P0, maize after 20 years of application (M20; and maize after 7 years of application (M7. Soil samples were collected in the 0-5, 5-10 and 10-20cm layers, in which density, porosity, aggregate stability, flocculation, penetration resistance, available water, and total clay content, total and particulate organic carbon, and C:N ratio were analyzed. The total organic carbon is sensitive to management and was not related to waste application, except in the 10-20cm layer of ryegrass pasture after three years of manuring. Reponses to waste application and land use and management systems were observed in the variables soil density and penetration resistance.

Catalytic growth of carbon nanotubes with large inner diameters

Directory of Open Access Journals (Sweden)

WEI REN ZHONG

2005-02-01

Full Text Available Carbon nanotubes (2.4 g/g catalyst, with large inner diameters were successfully synthesized through pyrolysis of methane on a Ni–Cu–Al catalyst by adding sodium carbonate into the carbon nanotubes growth system. The inner diameter of the carbon nanotubes prepared by this method is about 20–60 nm, while their outer diameter is about 40–80 nm. Transmission electron microscopy and X-ray diffraction were employed to investigate the morphology and microstructures of the carbon nanotubes. The analyses showed that these carbon nanotubes have large inner diameters and good graphitization. The addition of sodium carbonate into the reaction system brings about a slight decrease in the methane conversion and the yield of carbon. The experimental results showed that sodium carbonate is a mildly toxic material which influenced the catalytic activity of the Ni–Cu–Al catalyst and resulted in the formation of carbon nanotubes with large inner diameters. The growth mechanism of the carbon nanotubes with large inner diameters is discussed in this paper.

Properties of the chalcogenide–carbon nano tubes and graphene composite materials

International Nuclear Information System (INIS)

Singh, Abhay Kumar; Kim, JunHo; Park, Jong Tae; Sangunni, K.S.

2015-01-01

Highlights: • Chalcogenides. • Melt quenched. • Composite materials. • Multi walled carbon nano tubes. • Bilayer graphene. - Abstract: Composite can deliver more than the individual elemental property of the material. Specifically chalcogenide- multi walled carbon nano tubes and chalcogenide- bilayer graphene composite materials could be interesting for the investigation, which have been less covered by the investigators. We describe micro structural properties of Se 55 Te 25 Ge 20, Se 55 Te 25 Ge 20 + 0.025% multi walled carbon nano tubes and Se 55 Te 25 Ge 20 + 0.025% bilayer graphene materials. This gives realization of the alloying constituents inclusion/or diffusion inside the multi walled carbon nano tubes and bilayer graphene under the homogeneous parent alloy configuration. Raman spectroscopy, X-ray photoelectron spectroscopy, UV/Visible spectroscopy and Fourier transmission infrared spectroscopy have also been carried out under the discussion. A considerable core energy levels peak shifts have been noticed for the composite materials by the X-ray photoelectron spectroscopy. The optical energy band gaps are measured to be varied in between 1.2 and 1.3 eV. In comparison to parent (Se 55 Te 25 Ge 20 ) alloy a higher infrared transmission has been observed for the composite materials. Subsequently, variation in physical properties has been explained on the basis of bond formation in solids

Interlaminar improvement of carbon fiber/epoxy composites via depositing mixture of carbon nanotubes and sizing agent

Energy Technology Data Exchange (ETDEWEB)

Fang, Cuiqin [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Wang, Julin, E-mail: julinwang@126.com [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Tao [Beijing Institute of Ancient Architecture, Beijing 100050 (China)

2014-12-01

Graphical abstract: - Highlights: • COOH-CNTs can react with sizing agent, and the optimum reaction ratio was 1:20. • Carbon fibers were dipped into the mixture bath of CNTs and sizing agent. • SEM results indicate that fibers surfaces were coated with CNTs and sizing agent. • ILSS was increased by 67.01% for the composites after the mixture coating process. • Single fibers tensile strength was maintained after the deposited process. - Abstract: The effects of deposition to carbon fibers surfaces with mixture of functionalized multi-walled carbon fibers (MWCNTs) and sizing agent were investigated. Relationships between CNTs and sizing agent were studied with Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS) and Ubbelohde viscometer. The results revealed that CNTs could react with sizing agent at 120 °C, and optimal reaction occurs when mass ratio was about 1:20. Then, carbon fibers were immersed in mixed aqueous suspension of CNTs and sizing agent with the above ratio dispersed by ultrasonication. According to scanning electron microscope (SEM) observations, fibers surfaces were coated with CNTs and sizing agent. The static contact angle tests indicated wetting performance between fibers and epoxy resin were improved after deposited procedures. Interlaminar shear strength was increased by 67.01% for fibers/epoxy resin composites after mixture deposited process. Moreover, the tensile strength of single fibers after depositing showed a slightly increase compared with that of fibers without depositing layer.

Inferring absorbing organic carbon content from AERONET data

Science.gov (United States)

Arola, A.; Schuster, G.; Myhre, G.; Kazadzis, S.; Dey, S.; Tripathi, S. N.

2011-01-01

Black carbon, light-absorbing organic carbon (often called "brown carbon") and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated the amount of light-absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon) levels in biomass burning regions of South America and Africa are relatively high (about 15-20 mg m-2 during biomass burning season), while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30-35 mg m-2 during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by the global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while the opposite is true in urban areas in India and China.

Carbon monoxide, smoking, and atherosclerosis

Energy Technology Data Exchange (ETDEWEB)

Astrup, P

1973-10-01

Studies on the effects of carbon monoxide and smoking on atherosclerosis are reviewed. Nonsmokers do not run the risk of getting significantly elevated carboxyhemoglobin levels from automobile exhaust in the streets, however, they do run the risk of getting elevated carboxyhemoglobin levels from exposure to CO in closed areas such as garages and tunnels. Carboxyhemoglobin levels up to 20 percent may also be found in smokers. The central nervous system seems to be influenced by carboxyhemoglobin concentrations up to 20 percent. The myocardium may also be affected. Experimental work with rabbits exposed to carbon monoxide and cholesterol is described which proved that CO has a damaging effect on arterial walls, leading to increased permeability for various plasma components, to the formation of subendothelial edema, and to increased atheromatosis. The results indicate that the much higher risk of smokers of developing arterial disease in comparison to nonsmokers is mainly due to the inhaled CO in the tobacco smoke and not to nicotine. (Air Pollut. Abstr.)

Manganese Oxide on Carbon Fabric for Flexible Supercapacitors

Directory of Open Access Journals (Sweden)

Jianfeng Zhang

2016-01-01

Full Text Available We report the fabrication of uniform large-area manganese oxide (MnO2 nanosheets on carbon fabric which oxidized using O2 plasma treatment (MnO2/O2-carbon fabric via electrodeposition process and their implementation as supercapacitor electrodes. Electrochemical measurements demonstrated that MnO2/O2-carbon fabric exhibited capacitance as high as 275 F/g at a scan rate of 5 mV/s; in addition, it showed an excellent cycling performance (less than 20% capacitance loss after 10,000 cycles. All the results suggest that MnO2/O2-carbon fabric is a promising electrode material which has great potential for application on flexible supercapacitors.

Photodetector based on carbon nanotubes

Science.gov (United States)

Pavlov, A.; Kitsyuk, E.; Ryazanov, R.; Timoshenkov, V.; Adamov, Y.

2015-09-01

Photodetector based on carbon nanotubes (CNT) was investigated. Sensors were done on quartz and silicon susbtrate. Samples of photodetectors sensors were produced by planar technology. This technology included deposition of first metal layer (Al), lithography for pads formation, etching, and formation of local catalyst area by inverse lithography. Vertically-aligned multi-wall carbon nanotubes were directly synthesized on substrate by PECVD method. I-V analysis and spectrum sensitivity of photodetector were investigated for 0.4 μm - 1.2 μm wavelength. Resistivity of CNT layers over temperature was detected in the range of -20°C to 100°C.

Carbon charges and natural gas use in China

International Nuclear Information System (INIS)

Skeer, Jeffrey; Wang Yanjia

2006-01-01

Substitution of natural gas for coal in China's power sector could significantly reduce emissions of carbon dioxide, but gas-fired power is generally more costly than coal-fired power in China today. This paper explores how carbon charges and carbon sequestration technology might tip the balance in favour of gas. The costs of electricity from new coal-fired and gas-fired power plants in China are compared under various assumptions about fuel costs, exchange rates, carbon dioxide charges, and application of carbon sequestration technology. Under average cost conditions today, gas-fired power is roughly two-thirds more costly than coal-fired power. But with a charge of $20/tonne of carbon dioxide, the costs of gas- and coal-fired power would typically be about equal. Over the longer term, carbon sequestration technology could be economical with a carbon dioxide charge of $22/tonne or more under typical cost conditions, but gas with sequestration would not have a clear cost advantage over coal with sequestration unless the charge exceeded $35/tonne

Pyrolysis and Combustion Kinetics of Raw and Carbonized Cottonwood and Switchgrass Agroforests

Directory of Open Access Journals (Sweden)

Sammy Sadaka

2015-06-01

Full Text Available Raw biomass is not commonly suitable as feedstock for existing power plants, mainly because of the substantial required infrastructural changes. As a result, most raw feedstock requires pre-treatment to improve its physical and thermal characteristics. Biomass carbonization is one of the pre-treatments that produces charcoal-like feedstock. This paper explores the effects of the carbonization process on the physiochemical characteristics of biomass produced from two cottonwood clones, S7C20 and ST66, and switchgrass (var. Alamo. Additionally, it studies the thermal degradation kinetics of raw and carbonized agroforestry products in nitrogen and air environments. Feedstock samples were carbonized in a batch reactor at 400 °C in an oxygen-free environment for 2 hours. Carbonization decreased biomass bulk density, moisture content, and volatile solids while increasing fixed carbon, ash content, pH, and heating values. The heating value of S7C20, ST66, and switchgrass increased by 58.6%, 60.3%, and 69.7%, respectively. Carbonization increased the activation energy values under the condition of pyrolysis and decreased these values under the condition of combustion. The carbonization process produced a charcoal-like feedstock that may be processed with coal or even replace it.

FOOD SOURCES AND CARBON BUDGET OF CHINESE PRAWN PENAEUS CHINENSIS

Institute of Scientific and Technical Information of China (English)

董双林; 张硕; 王芳

2002-01-01

This study deals with contribution of artificial food pellet and natural food to Chinese prawn (Penaeus orientalis) growth in a semiintensive culture pond. The prawn carbon consumption, budget, and the effects of some factors on the budget were investigated. The results showed that 26.2% of P. orientalis growth carbon came from formulated feed at the initial culture stage (when the prawns were 0.06±0.01 g in wet weight), and was 62.5% when the prawns were 9.56±1.04 g. The remaining part of the growth carbon was derived from organic fertilizer and natural food. The highest growth rate occurred at 20×10-3 salinity. Suitable salinity for culturing Chinese prawn was (20-28)×10-3.

Technique for production of graphite-carbon products

Energy Technology Data Exchange (ETDEWEB)

Antonov, A.N.; Bentsianovskaya, I.A.; Filatova, V.A.; Nabokov, V.S.; Nestor, V.P.; Zil' bergleyt, I.M.

1982-01-01

The technique for producing carbon-graphite products that includes filtration under a pressure of 0.1-015 MPa (through graphite stock) of an aqueous carbon material with the addition of surfactant, drying, and subsequent thermal treatment, is simplified and made less lengthy. Oxidized graphite is utilized with a prior addition of 1-10% water-soluble organic substance into the suspension -molasses, hemicellulose, sugar or polyacrylamide. A 0.03-1.5% suspension of oxidized graphite is utilized, with a particle size of 0.02-0.1 mkm. Thermal processing is done in a carbon fill, at a rate of 10-20 degrees/hour to 700-800/sup 0/, maintained 2-3 hours.

Corporate Carbon Footprinting as Techno-political Practice

DEFF Research Database (Denmark)

Lippert, Ingmar

2017-01-01

’ matter? I explore how emissions come into being; carbon accounting emerges as techno-political practice, fraught with non-transparency. This chapter argues that ‘successful’ corporate carbon accounting practices efficiently and skilfully ignore significant political implications of the company......'s practical relation to climate change. ‘Successful’ in this case signifies what matters for the company to compete well in capitalist markets. By examining voluntary carbon accounting at a financial services corporation, I invite an engagement with how the technicality and politics of carbon interrelate...... in accounting. I ground my analysis in ethnographic fieldwork across 20 months in the Corporate Social Responsibility (CSR) unit at one of the 50 largest companies globally. Over this period, I supported the CSR unit’s management of their sustainability data, in exchange for overt and explicit research access...

Massive carbon addition to an organic-rich Andosol increased the subsoil but not the topsoil carbon stock

Directory of Open Access Journals (Sweden)

A. Zieger

2018-05-01

Full Text Available Andosols are among the most carbon-rich soils, with an average of 254 Mg ha−1 organic carbon (OC in the upper 100 cm. A current theory proposes an upper limit for OC stocks independent of increasing carbon input, because of finite binding capacities of the soil mineral phase. We tested the possible limits in OC stocks for Andosols with already large OC concentrations and stocks (212 g kg−1 in the first horizon, 301 Mg ha−1 in the upper 100 cm. The soils received large inputs of 1800 Mg OC ha−1 as sawdust within a time period of 20 years. Adjacent soils without sawdust application served as controls. We determined total OC stocks as well as the storage forms of organic matter (OM of five horizons down to 100 cm depth. Storage forms considered were pyrogenic carbon, OM of < 1.6 g cm−3 density and with little to no interaction with the mineral phase, and strongly mineral-bonded OM forming particles of densities between 1.6 and 2.0 g cm−3 or > 2.0 g cm−3. The two fractions > 1.6 g cm−3 were also analysed for aluminium-organic matter complexes (Al–OM complexes and imogolite-type phases using ammonium-oxalate–oxalic-acid extraction and X-ray diffraction (XRD. Pyrogenic organic carbon represented only up to 5 wt % of OC, and thus contributed little to soil OM. In the two topsoil horizons, the fraction between 1.6 and 2.0 g cm−3 had 65–86 wt % of bulk soil OC and was dominated by Al–OM complexes. In deeper horizons, the fraction > 2.0 g cm−3 contained 80–97 wt % of the bulk soil's total OC and was characterized by a mixture of Al–OM complexes and imogolite-type phases, with proportions of imogolite-type phases increasing with depth. In response to the sawdust application, only the OC stock at 25–50 cm depth increased significantly (α = 0.05, 1 − β = 0.8. The increase was entirely due to increased OC in the two fractions > 1.6�

Determination of Chemical States of Mercury on Activated Carbon Using XANES

International Nuclear Information System (INIS)

Takaoka, Masaki; Takeda, Nobuo; Oshita, Kazuyuki; Yamamoto, Takashi; Tanaka, Tsunehiro; Uruga, Tomoya

2007-01-01

Although the adsorption of mercury vapor onto activated carbon is a widely used technology to prevent environmental release, the adsorption mechanism is not clearly understood. In this study, we determined the chemical states of mercury on two kinds of activated carbon using X-ray absorption near-edge spectroscopy (XANES) to elucidate the adsorption mechanism. The adsorption experiments of elemental mercury onto activated carbon were conducted under air and nitrogen atmospheres at temperatures of 20 and 160 deg. C. Two types of activated carbon were prepared. X-ray absorption fine structure (XAFS) measurements were carried out on beamline BL01B1 at SPring-8. Hg-LIII edge XANES spectra suggested that chemical adsorption of elemental mercury on the activated carbon occurred in the 20-160 deg. C temperature range. According to the XANES spectra, a difference occurred in the chemical states of mercury between AC no. 1 and AC no. 2. The Hg XANES spectra on AC no. 1 were similar to those of Hg2Cl2 and HgS, and the Hg XANES spectra on AC no. 2 were similar to that of HgO, which suggested that nitric acid treatment removed sulfur from AC no. 1 and functional groups that were strong oxidizers on the surface of AC no. 2 created HgO. According to the EXAFS oscillation, a difference occurred in the chemical states of mercury on AC no. 1 between 20 and 160 deg. C. We found that impurities and oxidant functional groups on activated carbon play key roles in mercury adsorption

Carbon isotopes and concentrations in mid-oceanic ridge basalts

International Nuclear Information System (INIS)

Pineau, F.; Javoy, M.

1983-01-01

In order to estimate carbon fluxes at mid-ocean ridges and carbon isotopic compositions in the convective mantle, we have studied carbon concentrations and isotopic compositions in tholeiitic glasses from the FAMOUS zone (Mid-Atlantic Ridge at 36 0 N) and East Pacific Rise from 21 0 N (RITA zone) to 20 0 S. These samples correspond essentially to the whole spectrum of spreading rates (2-16 cm/yr). The contain: -CO 2 vesicles in various quantities (3-220 ppm C) with delta 13 C between -4 and -9per mille relative to PDB, in the range of carbonatites and diamonds. - Carbonate carbon (3-100 ppm C) with delta 13 C between -2.6 and -20.0per mille relative to PDB. - Dissolved carbon at a concentration of 170+-10 ppm under 250 bar pressure with delta 13 C from -9 to -21per mille relative to PDB. This dissolved carbon, not contained in large CO 2 vesicles, corresponds to a variety of chemical forms among which part of the above carbonates, microscopic CO 2 bubbles and graphite. The lightest portions of this dissolved carbon are extracted at low temperatures (400-600 0 C) whereas the CO 2 from the vesicles is extracted near fusion temperature. These features can be explained by outgassing processes in two steps from the source region of the magma: (1) equilibrium outgassing before the second percolation threshold, where micron size bubbles are continuously reequilibrated with the magma; (2) distillation after the second percolation threshold when larger bubbles travel faster than magma concentrations to the surface. The second step may begin at different depths apparently related to the spreading rate, shallower for fast-spreading ridges than for slow-spreading ridges. (orig./WL)

The Properties of SBR/ENR50 Blend Containing Nanoclay/Carbon Black Dual Filler System Cured by Electron Beam

Directory of Open Access Journals (Sweden)

Sima Ahmadi-Shooli

2017-05-01

Full Text Available Nanocomposites based on an SBR/ENR50 rubber blend with the blend ratio of 50/50 using Cloisite 15A nanoclay (5 and 10 phr and carbon black (20 phr were prepared by melt mixing process. The rubber compounds were crosslinked by electron beam irradiation process at 50 and 100 kGy doses. A reference sample containing carbon black at 35 phr was prepared using a conventional sulphur curing system. The gel content of the samples was specified using gel fraction measurement. The results showed the maximum gel content for the sample having 5 phr nanoclay and 20 phr carbon black. The dynamic mechanical properties, including the storage modulus, loss modulus, and loss factor, of the nanocomposites were evaluated using dynamic mechanical analysis (DMA tests. The results indicated that, in spite of a well dispersed nanoclay in samples containing 10 phr nanoclay and 20 phr carbon black, a minimum loss factor was observed in the sample containing 5 phr nanoclay and 20 phr carbon black at 100 kGy. On the other hand, the storage modulus of the reference sample was found to be higher than that of the sample with 5 phr nanoclay and 20 phr carbon black. The mechanical properties, including the tensile strength, stress at 100%, 200%, and 300% elongation and the percentage of elongation were measured by a tensile machine. The results showed an increase in tensile strength and the stress at different elongations for a sample with 5 phr nanoclay and 20 phr carbon black compared to the reference sample. In the corresponding SEM images of the samples having nanoclay and carbon black irradiated at 100 kGy a significantly higher surface roughness was observed.

Cryogenic Calcite: A Morphologic and Isotopic Analog to the ALH84001 Carbonates

Science.gov (United States)

Niles, P. B.; Leshin, L. A.; Socki, R. A.; Guan, Y.; Ming, D. W.; Gibson, E. K.

2004-01-01

Martian meteorite ALH84001 carbonates preserve large and variable microscale isotopic compositions, which in some way reflect their formation environment. These measurements show large variations (>20%) in the carbon and oxygen isotopic compositions of the carbonates on a 10-20 micron scale that are correlated with chemical composition. However, the utilization of these data sets for interpreting the formation conditions of the carbonates is complex due to lack of suitable terrestrial analogs and the difficulty of modeling under non-equilibrium conditions. Thus, the mechanisms and processes are largely unknown that create and preserve large microscale isotopic variations in carbonate minerals. Experimental tests of the possible environments and mechanisms that lead to large microscale isotopic variations can help address these concerns. One possible mechanism for creating large carbon isotopic variations in carbonates involves the freezing of water. Carbonates precipitate during extensive CO2 degassing that occurs during the freezing process as the fluid s decreasing volume drives CO2 out. This rapid CO2 degassing results in a kinetic isotopic fractionation where the CO2 gas has a much lighter isotopic composition causing an enrichment of 13C in the remaining dissolved bicarbonate. This study seeks to determine the suitability of cryogenically formed carbonates as analogs to ALH84001 carbonates. Specifically, our objective is to determine how accurately models using equilibrium fractionation factors approximate the isotopic compositions of cryogenically precipitated carbonates. This includes determining the accuracy of applying equilibrium fractionation factors during a kinetic process, and determining how isotopic variations in the fluid are preserved in microscale variations in the precipitated carbonates.

Initial reaction between CaO and SO₂ under carbonating and non-carbonating conditions

DEFF Research Database (Denmark)

Rasmussen, Martin Hagsted; Wedel, Stig; Pedersen, Kim H.

2015-01-01

The initial kinetics of the CaO/SO2 reaction have been investigated for reaction times shorter than 1s and in the temperature interval between 450 and 600°C under both carbonating and non-carbonating conditions (0-20 vol% CO2) to clarify how recirculating CaO influences the emission of SO2 from...... showed that the CaO conversion with respect to SO2 declined when the CO2 concentration was increased. Under all conditions, larger specific surface areas of CaO gave higher reaction rates with SO2. Higher temperatures had a positive effect on the reaction between SO2 and CaO under non......-carbonating conditions, but no or even a negative effect under carbonating conditions. The results led to the conclusion that SO2 released from raw meal in the upper stages of the preheater does not to any significant extent react with CaO recirculating in the preheater tower....

Carbon determination in natural crystals of olivines of deeporigin

International Nuclear Information System (INIS)

Shilobreeva, S.N.; Kadik, A.A.; Minaev, V.M.; Kazakov, S.S.; Kuz'min, L.E.; Moskovskij Inzhenerno-Fizicheskij Inst.; AN SSSR, Moscow. Inst. Yadernykh Issledovanij)

1987-01-01

Activation analysis and nuclear reaction analysis with registration of energy spectrum of forming prompt particles are used to determine carbon concentration and distribution in monocrystals of olivines. Carbon determination in olivine volume was carried out by activation analysis by 12 C(d, n) 13 N reaction and surface content - by registration of protons resulting from 12 C(d, p) 13 C reaction. The deuteron energy being 1.8-2.7 MeV, carbon determination limit and the analysis error were 10 -3 and 20 relat.%, respectively. By means of IR spectroscopy it is shown that carbon constitutes part of crystal lattice of olivines in monatomic form

Carbon Taxes. A Review of Experience and Policy Design Considerations

Energy Technology Data Exchange (ETDEWEB)

Sumner, Jenny [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bird, Lori [National Renewable Energy Lab. (NREL), Golden, CO (United States); Smith, Hillary [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2009-12-01

State and local governments in the United States are evaluating a wide range of policies to reduce carbon emissions, including, in some instances, carbon taxes, which have existed internationally for nearly 20 years. This report reviews existing carbon tax policies both internationally and in the United States. It also analyzes carbon policy design and effectiveness. Design considerations include which sectors to tax, where to set the tax rate, how to use tax revenues, what the impact will be on consumers, and how to ensure emissions reduction goals are achieved. Emission reductions that are due to carbon taxes can be difficult to measure, though some jurisdictions have quantified reductions in overall emissions and other jurisdictions have examined impacts that are due to programs funded by carbon tax revenues.

Carbon Taxes: A Review of Experience and Policy Design Considerations

Energy Technology Data Exchange (ETDEWEB)

Sumner, J.; Bird, L.; Smith, H.

2009-12-01

State and local governments in the United States are evaluating a wide range of policies to reduce carbon emissions, including, in some instances, carbon taxes, which have existed internationally for nearly 20 years. This report reviews existing carbon tax policies both internationally and in the United States. It also analyzes carbon policy design and effectiveness. Design considerations include which sectors to tax, where to set the tax rate, how to use tax revenues, what the impact will be on consumers, and how to ensure emissions reduction goals are achieved. Emission reductions that are due to carbon taxes can be difficult to measure, though some jurisdictions have quantified reductions in overall emissions and other jurisdictions have examined impacts that are due to programs funded by carbon tax revenues.

Carbon activation process for increased surface accessibility in electrochemical capacitors

Science.gov (United States)

Doughty, Daniel H.; Eisenmann, Erhard T.

2001-01-01

A process for making carbon film or powder suitable for double capacitor electrodes having a capacitance of up to about 300 F/cm.sup.3 is disclosed. This is accomplished by treating in aqueous nitric acid for a period of about 5 to 15 minutes thin carbon films obtained by carbonizing carbon-containing polymeric material having a high degree of molecular directionality, such as polyimide film, then heating the treated carbon film in a non-oxidizing atmosphere at a non-graphitizing temperature of at least 350.degree. C. for about 20 minutes, and repeating alternately the nitric acid step and the heating step from 7 to 10 times. Capacitors made with this carbon may find uses ranging from electronic devices to electric vehicle applications.

The influence of non-CO2 forcings on cumulative carbon emissions budgets

Science.gov (United States)

Tokarska, Katarzyna B.; Gillett, Nathan P.; Arora, Vivek K.; Lee, Warren G.; Zickfeld, Kirsten

2018-03-01

Carbon budgets provide a useful tool for policymakers to help meet the global climate targets, as they specify total allowable carbon emissions consistent with limiting warming to a given temperature threshold. Non-CO2 forcings have a net warming effect in the Representative Concentration Pathways (RCP) scenarios, leading to reductions in remaining carbon budgets based on CO2 forcing alone. Carbon budgets consistent with limiting warming to below 2.0 °C, with and without accounting for the effects of non-CO2 forcings, were assessed in inconsistent ways by the Intergovernmental Panel on Climate Change (IPCC), making the effects of non-CO2 forcings hard to identify. Here we use a consistent approach to compare 1.5 °C and 2.0 °C carbon budgets with and without accounting for the effects of non-CO2 forcings, using CO2-only and RCP8.5 simulations. The median allowable carbon budgets for 1.5 °C and 2.0 °C warming are reduced by 257 PgC and 418 PgC, respectively, and the uncertainty ranges on the budgets are reduced by more than a factor of two when accounting for the net warming effects of non-CO2 forcings. While our overall results are consistent with IPCC, we use a more robust methodology, and explain the narrower uncertainty ranges of carbon budgets when non-CO2 forcings are included. We demonstrate that most of the reduction in carbon budgets is a result of the direct warming effect of the non-CO2 forcings, with a secondary contribution from the influence of the non-CO2 forcings on the carbon cycle. Such carbon budgets are expected to play an increasingly important role in climate change mitigation, thus understanding the influence of non-CO2 forcings on these budgets and their uncertainties is critical.

Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

Science.gov (United States)

Steiner, S. A.; Baumann, T. F.; Kong, J.; Satcher, J. H.; Dresselhaus, M. S.

2007-02-20

We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

Energy Technology Data Exchange (ETDEWEB)

Steiner, S A; Baumann, T F; Kong, J; Satcher, J H; Dresselhaus, M S

2007-02-15

We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

Experimental determination of boron and carbon thermodynamic activities in the carbide phase of the boron-carbon system

International Nuclear Information System (INIS)

Froment, A.K.

1990-01-01

- The boron-carbon phase diagram presents a single phase area ranging from 9 to 20 atomic percent of carbon. The measurement of carbon activity, in this range of composition, has been measured according to the following methods: - quantitative analysis of the methane-hydrogen mixture in equilibrium with the carbide, - high temperature mass spectrometry measurements. The first method turned out to be a failure; however, the apparatus used enabled the elaboration of a B 4 C composition pure phase from a two-phase (B 4 C + graphite) industrial product. The results obtained with the other two methods are consistent and lead to a law expressing the increase of the carbon activity in relation with the amount of this element; the high temperature mass spectrometry method has also made it possible to measure the boron activity which decreases when the carbon activity increases, but with a variation of amplitude much lower, according to the theoretical calculations. These results are a first step towards the knowledge of the boron carbide thermodynamical data for compositions different from B 4 C [fr

Characterization and organic electric-double-layer-capacitor application of KOH activated coal-tar-pitch-based carbons: Effect of carbonization temperature

Science.gov (United States)

Choi, Poo Reum; Lee, Eunji; Kwon, Soon Hyung; Jung, Ji Chul; Kim, Myung-Soo

2015-12-01

The present study reports the influence of pre-carbonization on the properties of KOH-activated coal tar pitch (CTP). The change of crystallinity and pore structure of pre-carbonized CTPs as well as their activated carbons (ACs) as function of pre-carbonization temperature are investigated. The crystallinity of pre-carbonized CTPs increases with increasing the carbonization temperature up to 600 °C, but a disorder occurs during the carbonization around 700 °C and an order happens gradually with increasing the carbonization temperatures in range of 800-1000 °C. The CTPs pre-carbonized at high temperatures are more difficult to be activated with KOH than those pre-carbonized at low temperatures due to the increase of micro-crystalline size and the decrease of surface functional groups. The micro-pores and meso-pores are well developed at around 1.0 nm and 2.4 nm, respectively, as the ACs are pre-carbonized at temperatures of 500-600 °C, exhibiting high specific capacitances as electrode materials for electric double layer capacitor (EDLC). Although the specific surface area (SSA) and pore volume of ACs pre-carbonized at temperatures of 900-1000 °C are extraordinary low (non-porous) as compared to those of AC pre-carbonized at 600 °C, their specific capacitances are comparable to each other. The large specific capacitances with low SSA ACs can be attributed to the structural change resulting from the electrochemical activation during the 1st charge above 2.0 V.

Increased topsoil carbon stock across China's forests.

Science.gov (United States)

Yang, Yuanhe; Li, Pin; Ding, Jinzhi; Zhao, Xia; Ma, Wenhong; Ji, Chengjun; Fang, Jingyun

2014-08-01

Biomass carbon accumulation in forest ecosystems is a widespread phenomenon at both regional and global scales. However, as coupled carbon-climate models predicted, a positive feedback could be triggered if accelerated soil carbon decomposition offsets enhanced vegetation growth under a warming climate. It is thus crucial to reveal whether and how soil carbon stock in forest ecosystems has changed over recent decades. However, large-scale changes in soil carbon stock across forest ecosystems have not yet been carefully examined at both regional and global scales, which have been widely perceived as a big bottleneck in untangling carbon-climate feedback. Using newly developed database and sophisticated data mining approach, here we evaluated temporal changes in topsoil carbon stock across major forest ecosystem in China and analysed potential drivers in soil carbon dynamics over broad geographical scale. Our results indicated that topsoil carbon stock increased significantly within all of five major forest types during the period of 1980s-2000s, with an overall rate of 20.0 g C m(-2) yr(-1) (95% confidence interval, 14.1-25.5). The magnitude of soil carbon accumulation across coniferous forests and coniferous/broadleaved mixed forests exhibited meaningful increases with both mean annual temperature and precipitation. Moreover, soil carbon dynamics across these forest ecosystems were positively associated with clay content, with a larger amount of SOC accumulation occurring in fine-textured soils. In contrast, changes in soil carbon stock across broadleaved forests were insensitive to either climatic or edaphic variables. Overall, these results suggest that soil carbon accumulation does not counteract vegetation carbon sequestration across China's forest ecosystems. The combination of soil carbon accumulation and vegetation carbon sequestration triggers a negative feedback to climate warming, rather than a positive feedback predicted by coupled carbon-climate models

[Carbon sequestration in soil particle-sized fractions during reversion of desertification at Mu Us Sand land.

Science.gov (United States)

Ma, Jian Ye; Tong, Xiao Gang; Li, Zhan Bin; Fu, Guang Jun; Li, Jiao; Hasier

2016-11-18

The aim of this study was to investigate the effects of carbon sequestration in soil particle-sized fractions during reversion of desertification at Mu Us Sand Land, soil samples were collected from quicksand land, semifixed sand and fixed sand lands that were established by the shrub for 20-55 year-old and the arbor for 20-50 year-old at sand control region of Yulin in Northern Shaanxi Province. The dynamics and sequestration rate of soil organic carbon (SOC) associated with sand, silt and clay were measured by physical fractionation method. The results indicated that, compared with quicksand area, the carbon content in total SOC and all soil particle-sized fractions at bothsand-fixing sand forest lands showed a significant increasing trend, and the maximum carbon content was observed in the top layer of soils. From quicksand to fixed sand land with 55-year-old shrub and 50-year-old arbor, the annual sequestration rate of carbon stock in 0-5 cm soil depth was same in silt by 0.05 Mg·hm -2 ·a -1 . The increase rate of carbon sequestration in sand was 0.05 and 0.08 Mg·hm -2 ·a -1 , and in clay was 0.02 and 0.03 Mg·hm -2 ·a -1 at shrubs and arbors land, respectively. The increase rate of carbon sequestration in 0-20 cm soil layer for all the soil particles was averagely 2.1 times as that of 0-5 cm. At the annual increase rate of carbon, the stock of carbon in sand, silt and clay at the two fixed sand lands were increased by 6.7, 18.1 and 4.4 times after 50-55 year-old reversion of quicksand land to fixed sand. In addition, the average percentages that contributed to accumulation of total SOC by different particles in 0-20 cm soil were in the order of silt carbon (39.7%)≈sand carbon (34.6%) > clay carbon (25.6%). Generally, the soil particle-sized fractions had great carbon sequestration potential during reversion of desertification in Mu Us Sand Land, and the slit and sand were the main fractions for carbon sequestration at both fixed sand lands.

Inferring absorbing organic carbon content from AERONET data

Directory of Open Access Journals (Sweden)

A. Arola

2011-01-01

Full Text Available Black carbon, light-absorbing organic carbon (often called "brown carbon" and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated the amount of light–absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon levels in biomass burning regions of South America and Africa are relatively high (about 15–20 mg m⁻² during biomass burning season, while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30–35 mg m⁻² during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by the global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while the opposite is true in urban areas in India and China.

Influence of sample composition on aerosol organic and black carbon determinations

Energy Technology Data Exchange (ETDEWEB)

Novakov, T.; Corrigan, C.E.

1995-07-01

In this paper we present results on characterization of filter-collected redwood (Sequoia sempevirens)-needle and eucalyptus smoke particles by thermal, optical, and solvent extraction methods. Our results demonstrate that organic and black carbon concentrations determined by thermal and optical methods are not only method dependent, but also critically influenced by the overall chemical composition of the samples. These conclusions are supported by the following: (1) the organic fraction of biomass smoke particles analyzed includes a component, ranging in concentration from about 6-20% of total carbon or from 16-30% of organic carbon, that is relatively non-volatile and has a combustion temperature close to that of black carbon; (2) presence of K or Na in biomass smoke samples lowers the combustion temperatures of this organic component and of black carbon, making their combustion properties indistinguishable; (3) about 20% of total organic material is nonvolatile when heated to 550{degrees}C in an inert atmosphere. Consequently, thermal methods that rely on a specific temperature to separate organic from black carbon may either underestimate or overestimate the black and organic carbon concentrations, depending on the amounts of Na and K and on the composition and concentration of organic material present in a sample. These analytical uncertainties and, under some conditions, absorption by organic material may contribute to the variability of empirically derived proportionality between light transmission through filter deposits and black carbon concentrations.

Influence of sample composition on aerosol organic and black carbon determinations

International Nuclear Information System (INIS)

Novakov, T.; Corrigan, C.E.

1995-07-01

In this paper we present results on characterization of filter-collected redwood (Sequoia sempevirens)-needle and eucalyptus smoke particles by thermal, optical, and solvent extraction methods. Our results demonstrate that organic and black carbon concentrations determined by thermal and optical methods are not only method dependent, but also critically influenced by the overall chemical composition of the samples. These conclusions are supported by the following: (1) the organic fraction of biomass smoke particles analyzed includes a component, ranging in concentration from about 6-20% of total carbon or from 16-30% of organic carbon, that is relatively non-volatile and has a combustion temperature close to that of black carbon; (2) presence of K or Na in biomass smoke samples lowers the combustion temperatures of this organic component and of black carbon, making their combustion properties indistinguishable; (3) about 20% of total organic material is nonvolatile when heated to 550 degrees C in an inert atmosphere. Consequently, thermal methods that rely on a specific temperature to separate organic from black carbon may either underestimate or overestimate the black and organic carbon concentrations, depending on the amounts of Na and K and on the composition and concentration of organic material present in a sample. These analytical uncertainties and, under some conditions, absorption by organic material may contribute to the variability of empirically derived proportionality between light transmission through filter deposits and black carbon concentrations

Carbon Concentration and Carbon-to-Nitrogen Ratio Influence Submerged-Culture Conidiation by the Potential Bioherbicide Colletotrichum truncatum NRRL 13737

Science.gov (United States)

Jackson, Mark A.; Bothast, Rodney J.

1990-01-01

We assessed the influence of various carbon concentrations and carbon-to-nitrogen (C:N) ratios on Colletotrichum truncatum NRRL 13737 conidium formation in submerged cultures grown in a basal salts medium containing various amounts of glucose and Casamino Acids. Under the nutritional conditions tested, the highest conidium concentrations were produced in media with carbon concentrations of 4.0 to 15.3 g/liter. High carbon concentrations (20.4 to 40.8 g/liter) inhibited sporulation and enhanced the formation of microsclerotiumlike hyphal masses. At all the carbon concentrations tested, a culture grown in a medium with a C:N ratio of 15:1 produced more conidia than cultures grown in media with C:N ratios of 40:1 or 5:1. While glucose exhaustion was often coincident with conidium formation, cultures containing residual glucose sporulated and those with high carbon concentrations (>25 g/liter) exhausted glucose without sporulation. Nitrogen source studies showed that the levels of C. truncatum NRRL 13737 conidiation were similar for all protein hydrolysates tested. Reduced conidiation occurred when amino acid and inorganic nitrogen sources were used. Of the nine carbon sources evaluated, acetate as the sole carbon source resulted in the lowest level of sporulation. Images PMID:16348348

Carbon dioxide stripping in aquaculture -- part II: development of gas transfer models

Science.gov (United States)

Colt, John; Watten, Barnaby; Pfeiffer, Tim

2012-01-01

The basic mass transfer equation for gases such as oxygen and carbon dioxide can be derived from integration of the driving force equation. Because of the physical characteristics of the gas transfer processes, slightly different models are used for aerators tested under the non steady-state procedures, than for packed columns, or weirs. It is suggested that the standard condition for carbon dioxide should be 20 °C, 1 atm, CCO2=20 mg/kg, and XCO2=0.000285. The selection of the standard condition for carbon dioxide based on a fixed mole fraction ensures that standardized carbon dioxide transfer rates will be comparable even though the value of C*CO2 in the atmosphere is increasing with time. The computation of mass transfer for carbon dioxide is complicated by the impact of water depth and gas phase enrichment on the saturation concentration within the unit, although the importance of either factor depends strongly on the specific type of aerator. For some types of aerators, the most accurate gas phase model remains to be determined for carbon dioxide. The assumption that carbon dioxide can be treated as a non-reactive gas in packed columns may apply for cold acidic waters but not for warm alkaline waters.

Biochar Preparation from Simulated Municipal Solid Waste Employing Low Temperature Carbonization Process

Science.gov (United States)

Areeprasert, C.; Leelachaikul, P.; Jangkobpattana, G.; Phumprasop, K.; Kiattiwat, T.

2018-02-01

This paper presents an investigation on carbonization process of simulated municipal solid waste (MSW). Simulated MSW consists of a representative of food residue (68%), plastic waste (20%), paper (8%), and textile (4%). Laboratory-scale carbonization was performed in this study using a vertical-type pyrolyzer varying carbonization temperature (300, 350, 400, and 450 °C) and heating rate (5, 10, 15, and 20 °C/min). Appearance of the biochar product was in black and the volume was significantly reduced. Low carbonization temperature (300 °C) might not completely decompose plastic materials in MSW. Results showed that the carbonization at the temperature of 400 °C with the heating rate of 5 °C/min was the optimal condition. The yield of biochar from the optimal process was 50.6% with the heating value of 26.85 MJ/kg. Energy input of the process was attributed to water evaporation and the decomposition of plastics and paper. Energy output of the process was highest at the optimal condition. Energy output and input ratio was around 1.3-1.7 showing the feasibility of the carbonization process in all heating rate condition.

Carbonate hosted gold deposit in Tasmania, Australia

International Nuclear Information System (INIS)

Abadi, M.H.

1999-01-01

Full text: This study uses elemental and isotopic composition of carbonates associated with gold from Henty and Beaconsfield in Tasmania, Australia, to illustrate source of gold-bearing fluids, salinity, temperature and dissolution and reprecipitation of carbonate. The Beaconsfield and Henty gold mines are located in northern and western Tasmania respectively. Gold mineralisation in Beaconsfield occurs within the quartz-carbonate Tasmania Reef (Lower to Middle Palaeozoic sequence, Hills, 1998). The Henty gold mine is located at the base of the Cambrian Tyndall Group (volcano-sedimentary succession, White and McPhie, 1996) close to Henty Fault. Gold in carbonate samples from Henty ranges from 7.7 to 9360 ppm and in Beaconsfield ranges from 0.01 to 434 ppm. The amount of carbonate in samples from Henty and Beaconsfield gold mines varies from approximately 24 to 99.8%. Bivariate plot of Ca relative to total amounts of Mg, Fe and Mn illustrates that the major carbonate minerals at Beaconsfield and Henty gold mines are magnesian ankerite and calcite. The difference in carbonate mineralogy, at Henty and Beaconsfield gold mines, is attributed to the composition of fluids responsible for carbonate alteration. Gold and magnesium in Beaconsfield ankerite are derived from the leaching of Cambrian ultramafic rocks during the Devonian by the passage of meteoric fluids through tectonically affected Ordovician carbonates (Rao and Adabi, 1999). The total concentration of Fe and Mn are low (0.5 to 2%) in Henty and high (1 to 17.5%) in Beaconsfield ankerite, possibly due to oxidising conditions at Henty and reducing conditions at Beaconsfield gold mines during gold mineralisation. Variation of Sr values between Beaconsfield ankerite and Henty calcite is related to dissolution of limestone that increase Sr concentrations in gold mineralising fluids. Na values in both Beaconsfield (20 to 1100 ppm) and Henty carbonates (25 to 1650 ppm) suggest low salinity fluids responsible for gold

Raising the Corrosion Resistance of Low-Carbon Steels by Electrolytic-Plasma Saturation with Nitrogen and Carbon

Science.gov (United States)

Kusmanov, S. A.; Grishina, E. P.; Belkin, P. N.; Kusmanova, Yu. V.; Kudryakova, N. O.

2017-05-01

Structural features of the external oxide layer and internal nitrided, carbonitrided and carburized layers in steels 10, 20 and St3 produced by the method of electrolytic plasma treatment are studied. Specimens of the steels are tested for corrosion in a naturally aerated 1-N solution of sodium chloride. The condition of the metal/sodium chloride solution interface is studied by the method of electrochemical impedance spectroscopy. It is shown that the corrosion resistance of low-carbon steels can be raised by anode electrolytic-plasma saturation with nitrogen and carbon. Recommendations are given on the choice of carbonitriding modes for structural steels.

Influences of carbon content and coating carbon thickness on properties of amorphous CoSnO3@C composites as anode materials for lithium-ion batteries

Science.gov (United States)

Fan, Fuqiang; Fang, Guoqing; Zhang, Ruixue; Xu, Yanhui; Zheng, Junwei; Li, Decheng

2014-08-01

A series of core-shell carbon coated amorphous CoSnO3 (CoSnO3@C) with different carbon content are synthesized. Effects of carbon content and coating carbon thickness on the physical and electrochemical performances of the samples were studied in detail. The samples were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), galvanostatic charge-discharge and AC impedance spectroscopy, respectively. The results indicate that controlling the concentration of aqueous glucose solution influences the generation of in-situ carbon layer thickness. The optimal concentration of aqueous glucose solution, carbon content and carbon layer thickness are suggested as 0.25 M, 35.1% and 20 nm, respectively. CoSnO3@C composite prepared under the optimal conditions exhibits excellent cycling performance, whose reversible capacity could reach 491 mA h g-1 after 100 cycles.

Measurement of the activity coefficient of carbon in steels in liquid sodium

International Nuclear Information System (INIS)

Surville, G.

1983-06-01

In sodium cooled fast reactors carbon is both a carbon impurity and element of structural materials. Carbon transfert through liquid sodium can produce carburization or decarburization of structural materials. Carbon content in sodium is determined with thin foils of austenitic alloys, when equilibrium is reached thermodynamic activity of carbon in sodium is deduced from carbon activity in alloys. Studied alloys are FeMn 20%, FeNi 30%, Z2CN 18-10 and Z3CND17-13. Carbon activity of alloys in sodium was between 5.10 -3 and 10 -1 at 600 and 650 0 C. Calibration was obtained with the alloys FeNi 30% in gaseous mixtures He-CO-CO 2 of known activity [fr

[Greenhouse gas emissions, carbon leakage and net carbon sequestration from afforestation and forest management: A review.

Science.gov (United States)

Liu, Bo Jie; Lu, Fei; Wang, Xiao Ke; Liu, Wei Wei

2017-02-01

Forests play an important role in climate change mitigation and concentration of CO 2 reduction in the atmosphere. Forest management, especially afforestation and forest protection, could increase carbon stock of forests significantly. Carbon sequestration rate of afforestation ranges from 0.04 to 7.52 t C·hm -2 ·a -1 , while that of forest protection is 0.33-5.20 t C·hm -2 ·a -1 . At the same time, greenhouse gas (GHG) is generated within management boundary due to the production and transportation of the materials consumed in relevant activities of afforestation and forest management. In addition, carbon leakage is also generated outside boundary from activity shifting, market effects and change of environments induced by forest management. In this review, we summarized the definition of emission sources of GHG, monitoring methods, quantity and rate of greenhouse gas emissions within boundary of afforestation and forest management. In addition, types, monitoring methods and quantity of carbon leakage outside boundary of forest management were also analyzed. Based on the reviewed results of carbon sequestration, we introduced greenhouse gas emissions within boundary and carbon leakage, net carbon sequestration as well as the countervailing effects of greenhouse gas emissions and carbon leakage to carbon sequestration. Greenhouse gas emissions within management boundary counteract 0.01%-19.3% of carbon sequestration, and such counteraction could increase to as high as 95% considering carbon leakage. Afforestation and forest management have substantial net carbon sequestration benefits, when only taking direct greenhouse gas emissions within boundary and measurable carbon leakage from activity shifting into consideration. Compared with soil carbon sequestration measures in croplands, afforestation and forest management is more advantageous in net carbon sequestration and has better prospects for application in terms of net mitigation potential. Along with the

Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results

Energy Technology Data Exchange (ETDEWEB)

Mattigod, Shas V.; Wellman, Dawn M.; Golovich, Elizabeth C.; Cordova, Elsa A.; Smith, Ronald M.

2010-12-01

CH2M HILL Plateau Remediation Company (CHPRC) is currently developing a 200-West Area groundwater pump-and-treat system as the remedial action selected under the Comprehensive Environmental Response, Compensation, and Liability Act Record of Decision for Operable Unit (OU) 200-ZP-1. This report documents the results of treatability tests Pacific Northwest National Laboratory researchers conducted to quantify the ability of selected activated carbon products (or carbons) to adsorb technetium-99 (Tc-99) from 200-West Area groundwater. The Tc-99 adsorption performance of seven activated carbons (J177601 Calgon Fitrasorb 400, J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, J177612 Norit GAC830, J177613 Norit GAC830, and J177617 Nucon LW1230) were evaluated using water from well 299-W19-36. Four of the best performing carbons (J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, and J177613 Norit GAC830) were selected for batch isotherm testing. The batch isotherm tests on four of the selected carbons indicated that under lower nitrate concentration conditions (382 mg/L), Kd values ranged from 6,000 to 20,000 mL/g. In comparison. Under higher nitrate (750 mg/L) conditions, there was a measureable decrease in Tc-99 adsorption with Kd values ranging from 3,000 to 7,000 mL/g. The adsorption data fit both the Langmuir and the Freundlich equations. Supplemental tests were conducted using the two carbons that demonstrated the highest adsorption capacity to resolve the issue of the best fit isotherm. These tests indicated that Langmuir isotherms provided the best fit for Tc-99 adsorption under low nitrate concentration conditions. At the design basis concentration of Tc 0.865 µg/L(14,700 pCi/L), the predicted Kd values from using Langmuir isotherm constants were 5,980 mL/g and 6,870 mL/g for for the two carbons. These Kd values did not meet the target Kd value of 9,000 mL/g. Tests

Utilization Of Carbon Nanotubes In Electromagnetic Wave Detectors

Directory of Open Access Journals (Sweden)

Muhammad Hanis Zakariah

2017-08-01

Full Text Available Direct detection of hydrocarbon by an active source using electromagnetic (EM energy termed seabed logging (SBL has shown very promising results. However, currently available electromagnetic wave technology has a number of challenges include sensitivity and frequency matching. This paper presents development of the carbon nanotubes (CNTs as electromagnetic wave detector due to outstanding properties of carbon nanotubes. They are currently one of the desired materials for advanced technologies. Two types of detectors were developed in this work, carbon nanotube-based (D1 and without nanotube-based (D2 detectors. Various configuration and arrangement for each type of detector were investigated to determine the one with the highest detection measurement and stability of frequency stability of detection system. It was found that 20 turn-coils coil placed at its centre gives the maximum detection of induction voltage, 39.61 mV. However, the 20 turn- coils with CNTs which gives 36.50 mV is the preferred EM detectors due to the stability in frequency of the detection system.

Palladium and palladium-tin supported on multi wall carbon nanotubes or carbon for alkaline direct ethanol fuel cell

Science.gov (United States)

Geraldes, Adriana Napoleão; Furtunato da Silva, Dionisio; Martins da Silva, Júlio César; Antonio de Sá, Osvaldo; Spinacé, Estevam Vitório; Neto, Almir Oliveira; Coelho dos Santos, Mauro

2015-02-01

Pd and PdSn (Pd:Sn atomic ratios of 90:10), supported on Multi Wall Carbon Nanotubes (MWCNT) or Carbon (C), are prepared by an electron beam irradiation reduction method. The obtained materials are characterized by X-Ray diffraction (XRD), Energy dispersive X-ray analysis (EDX), Transmission electron Microscopy (TEM) and Cyclic Voltammetry (CV). The activity for ethanol electro-oxidation is tested in alkaline medium, at room temperature, using Cyclic Voltammetry and Chronoamperometry (CA) and in a single alkaline direct ethanol fuel cell (ADEFC), in the temperature range of 60-90 °C. CV analysis finds that Pd/MWCNT and PdSn/MWCNT presents onset potentials changing to negative values and high current values, compared to Pd/C and PdSn/C electrocatalysts. ATR-FTIR analysis, performed during the CV, identifies acetate and acetaldehyde as principal products formed during the ethanol electro-oxidation, with low conversion to CO2. In single fuel cell tests, at 85 °C, using 2.0 mol L-1 ethanol in 2.0 mol L-1 KOH solutions, the electrocatalysts supported on MWCNT, also, show higher power densities, compared to the materials supported on carbon: PdSn/MWCNT, presents the best result (36 mW cm-2). The results show that the use of MWCNT, instead of carbon, as support, plus the addition of small amounts of Sn to Pd, improves the electrocatalytic activity for Ethanol Oxidation Reaction (EOR).

Hybrid carbon nanostructure assemblage for high performance pseudo-capacitors

Directory of Open Access Journals (Sweden)

A. K. Mishra

2012-06-01

Full Text Available Investigation of novel nanocomposites for pseudo-capacitors with high capacitance and energy density is the spotlight of current energy research. In the present work, hybrid carbon nanostructure assemblage of graphene and multiwalled carbon nanotubes has been used as carbon support to nanostructured RuO2 and polyaniline for high energy supercapacitors. Maximum specific capacitances of 110, 235 and 440 F g−1 at the voltage sweep rate of 10 mV s−1 and maximum energy densities of 7, 12.5 and 20.5 Wh kg−1 were observed for carbon assemblage and its RuO2 and polyanilne decorated nanocomposites, respectively, with 1M H2SO4 as electrolyte.

Preparation of carbon-free TEM microgrids by metal sputtering

International Nuclear Information System (INIS)

Janbroers, S.; Kruijff, T.R. de; Xu, Q.; Kooyman, P.J.; Zandbergen, H.W.

2009-01-01

A new method for preparing carbon-free, temperature-stable Transmission Electron Microscope (TEM) grids is presented. An 80% Au/20% Pd metal film is deposited onto a 'holey' microgrid carbon supported on standard mixed-mesh Au TEM grids. Subsequently, the carbon film is selectively removed using plasma cleaning. In this way, an all-metal TEM film is made containing the 'same' microgrid as the original carbon film. Although electron transparency of the foil is reduced significantly, the open areas for TEM inspection of material over these areas are maintained. The metal foil can be prepared with various thicknesses and ensures good electrical conductivity. The new Au/Pd grids are stable to at least 775 K under vacuum conditions.

Preparation of carbon-free TEM microgrids by metal sputtering.

Science.gov (United States)

Janbroers, S; de Kruijff, T R; Xu, Q; Kooyman, P J; Zandbergen, H W

2009-08-01

A new method for preparing carbon-free, temperature-stable Transmission Electron Microscope (TEM) grids is presented. An 80% Au/20% Pd metal film is deposited onto a 'holey' microgrid carbon supported on standard mixed-mesh Au TEM grids. Subsequently, the carbon film is selectively removed using plasma cleaning. In this way, an all-metal TEM film is made containing the 'same' microgrid as the original carbon film. Although electron transparency of the foil is reduced significantly, the open areas for TEM inspection of material over these areas are maintained. The metal foil can be prepared with various thicknesses and ensures good electrical conductivity. The new Au/Pd grids are stable to at least 775K under vacuum conditions.

Preparation of PtRu/Carbon hybrid materials by hydrothermal carbonization: A study of the Pt:Ru atomic ratio

International Nuclear Information System (INIS)

Tusi, Marcelo Marques; Brandalise, Michele; Correa, Olandir Vercino; Oliveira Neto, Almir; Linardi, Marcelo; Spinace, Estevam Vitorio; Villalba, Juan Carlo

2009-01-01

PtRu/Carbon materials with different Pt:Ru atomic ratios (30:70, 50:50, 60:40, 80:20 and 90:10) and 5 wt% of nominal metal load were prepared by hydrothermal carbonization using H 2 PtCl 6.6 H 2 O and RuCl 3. xH 2 O as metals sources and catalysts of the carbonization process and starch as carbon source and reducing agent. The obtained materials were treated at 900 deg C under argon and characterized by EDX, XRD and cyclic voltammetry. The electro-oxidation of methanol was studied by cyclic voltammetry and chronoamperometry using thin porous coating technique. The PtRu/Carbon materials showed Pt:Ru atomic ratios obtained by EDX similar to the nominal ones. XRD analysis showed that Pt face-cubic centered (FCC) and Ru hexagonal close-packed (HCP) phases coexist in the obtained materials. The average crystallite sizes of the Pt (FCC) phase were in the range of 8-12 nm. The material prepared with Pt:Ru atomic ratio of 50:50 showed the best performance for methanol electro-oxidation. (author)

20th-century industrial black carbon emissions altered Arctic climate forcing.

Science.gov (United States)

McConnell, Joseph R; Edwards, Ross; Kok, Gregory L; Flanner, Mark G; Zender, Charles S; Saltzman, Eric S; Banta, J Ryan; Pasteris, Daniel R; Carter, Megan M; Kahl, Jonathan D W

2007-09-07

Black carbon (BC) from biomass and fossil fuel combustion alters chemical and physical properties of the atmosphere and snow albedo, yet little is known about its emission or deposition histories. Measurements of BC, vanillic acid, and non-sea-salt sulfur in ice cores indicate that sources and concentrations of BC in Greenland precipitation varied greatly since 1788 as a result of boreal forest fires and industrial activities. Beginning about 1850, industrial emissions resulted in a sevenfold increase in ice-core BC concentrations, with most change occurring in winter. BC concentrations after about 1951 were lower but increasing. At its maximum from 1906 to 1910, estimated surface climate forcing in early summer from BC in Arctic snow was about 3 watts per square meter, which is eight times the typical preindustrial forcing value.

Re-crystallization of ITO films after carbon irradiation

Energy Technology Data Exchange (ETDEWEB)

Usman, Muhammad, E-mail: usmanm@ncp.edu.pk [Experimental Physics Laboratories, National Centre for Physics, Shahdara Valley Road, Quaid-i-Azam University, Islamabad (Pakistan); Khan, Shahid, E-mail: shahidkhan@zju.edu.cn [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Khan, Majid [Department of Physics, Quaid-i-Azam University, Islamabad (Pakistan); Abbas, Turab Ali [Experimental Physics Laboratories, National Centre for Physics, Shahdara Valley Road, Quaid-i-Azam University, Islamabad (Pakistan)

2017-01-15

Highlights: • Carbon irradiation on ITO destroys crystal structure until threshold ion fluence. • Carbon irradiation induced amorphization in ITO is recoverable at higher fluence. • Optical transmittance is reduced after carbon irradiation. • Electrical resistivity is increased after irradiation with carbon ions in ITO. • Bandgap is reduced with increasing fluence of carbon irradiation. - Abstract: 2.0 MeV carbon ion irradiation effects on Indium Tin Oxide (ITO) thin films on glass substrate are investigated. The films are irradiated with carbon ions in the fluence range of 1 × 10{sup 13} to 1 × 10{sup 15} ions/cm{sup 2}. The irradiation induced effects in ITO are compared before and after ion bombardment by systematic study of structural, optical and electrical properties of the films. The XRD results show polycrystalline nature of un-irradiated ITO films which turns to amorphous state after 1 × 10{sup 13} ions/cm{sup 2} fluence of carbon ions. Further increase in ion fluence to 1 × 10{sup 14} ions/cm{sup 2} re-crystallizes the structure and retains for even higher fluences. A gradual decrease in the electrical conductivity and transmittance of irradiated samples is observed with increasing ion fluence. The band gap of the films is observed to be decreased after carbon irradiation.

Re-crystallization of ITO films after carbon irradiation

International Nuclear Information System (INIS)

Usman, Muhammad; Khan, Shahid; Khan, Majid; Abbas, Turab Ali

2017-01-01

Highlights: • Carbon irradiation on ITO destroys crystal structure until threshold ion fluence. • Carbon irradiation induced amorphization in ITO is recoverable at higher fluence. • Optical transmittance is reduced after carbon irradiation. • Electrical resistivity is increased after irradiation with carbon ions in ITO. • Bandgap is reduced with increasing fluence of carbon irradiation. - Abstract: 2.0 MeV carbon ion irradiation effects on Indium Tin Oxide (ITO) thin films on glass substrate are investigated. The films are irradiated with carbon ions in the fluence range of 1 × 10"1"3 to 1 × 10"1"5 ions/cm"2. The irradiation induced effects in ITO are compared before and after ion bombardment by systematic study of structural, optical and electrical properties of the films. The XRD results show polycrystalline nature of un-irradiated ITO films which turns to amorphous state after 1 × 10"1"3 ions/cm"2 fluence of carbon ions. Further increase in ion fluence to 1 × 10"1"4 ions/cm"2 re-crystallizes the structure and retains for even higher fluences. A gradual decrease in the electrical conductivity and transmittance of irradiated samples is observed with increasing ion fluence. The band gap of the films is observed to be decreased after carbon irradiation.

Modelling and mapping the topsoil organic carbon content for Tanzania

Science.gov (United States)

Kempen, Bas; Kaaya, Abel; Ngonyani Mhaiki, Consolatha; Kiluvia, Shani; Ruiperez-Gonzalez, Maria; Batjes, Niels; Dalsgaard, Soren

2014-05-01

Soil organic carbon (SOC), held in soil organic matter, is a key indicator of soil health and plays an important role in the global carbon cycle. The soil can act as a net source or sink of carbon depending on land use and management. Deforestation and forest degradation lead to the release of vast amounts of carbon from the soil in the form of greenhouse gasses, especially in tropical countries. Tanzania has a high deforestation rate: it is estimated that the country loses 1.1% of its total forested area annually. During 2010-2013 Tanzania has been a pilot country under the UN-REDD programme. This programme has supported Tanzania in its initial efforts towards reducing greenhouse gas emission from forest degradation and deforestation and towards preserving soil carbon stocks. Formulation and implementation of the national REDD strategy requires detailed information on the five carbon pools among these the SOC pool. The spatial distribution of SOC contents and stocks was not available for Tanzania. The initial aim of this research, was therefore to develop high-resolution maps of the SOC content for the country. The mapping exercise was carried out in a collaborative effort with four Tanzanian institutes and data from the Africa Soil Information Service initiative (AfSIS). The mapping exercise was provided with over 3200 field observations on SOC from four sources; this is the most comprehensive soil dataset collected in Tanzania so far. The main source of soil samples was the National Forest Monitoring and Assessment (NAFORMA). The carbon maps were generated by means of digital soil mapping using regression-kriging. Maps at 250 m spatial resolution were developed for four depth layers: 0-10 cm, 10-20 cm, 20-30 cm, and 0-30 cm. A total of 37 environmental GIS data layers were prepared for use as covariates in the regression model. These included vegetation indices, terrain parameters, surface temperature, spectral reflectances, a land cover map and a small

Effect of carbon fiber dispersion on the mechanical properties of carbon fiber-reinforced cement-based composites

International Nuclear Information System (INIS)

Wang Chuang; Li Kezhi; Li Hejun; Jiao Gengsheng; Lu Jinhua; Hou Dangshe

2008-01-01

The preparation of carbon fiber-reinforced cement-based composites involved two-step dispersions of carbon fibers. Both steps affected greatly the mechanical properties of the composites. With the aid of ultrasonic wave, a new dispersant hydroxyethyl cellulose was used to help fiber dispersion in the first step. The fracture surface of the composites was observed by scanning electron microscopy. The distribution of major elements was analyzed by the energy dispersive spectroscopy and the composition was analyzed through X-ray diffraction. The flexural strength, tensile strength, modulus, and compression strength were measured. Results showed that the distribution of major elements varied with the variation of the fiber dispersion status. The compressive strength increased by 20%, the tensile strength was 2.4 times that of the material without carbon fibers, the modulus increased by 26.8%, whereas the flexure stress decreased by 12.9%

Altitudinal variation of soil organic carbon stocks in temperate forests of Kashmir Himalayas, India.

Science.gov (United States)

Ahmad Dar, Javid; Somaiah, Sundarapandian

2015-02-01

Soil organic carbon stocks were measured at three depths (0-10, 10-20, and 20-30 cm) in seven altitudes dominated by different forest types viz. Populus deltoides, 1550-1800 m; Juglans regia, 1800-2000 m; Cedrus deodara, 2050-2300 m; Pinus wallichiana, 2000-2300 m; mixed type, 2200-2400 m; Abies pindrow, 2300-2800 m; and Betula utilis, 2800-3200 m in temperate mountains of Kashmir Himalayas. The mean range of soil organic carbon (SOC) stocks varied from 39.07 to 91.39 Mg C ha(-1) in J. regia and B. utilis forests at 0-30 cm depth, respectively. Among the forest types, the lowest mean range of SOC at three depths (0-10, 10-20, and 20-30 cm) was observed in J. regia (18.55, 11.31, and 8.91 Mg C ha(-1), respectively) forest type, and the highest was observed in B. utilis (54.10, 21.68, and 15.60 Mg C ha(-1), respectively) forest type. SOC stocks showed significantly (R (2) = 0.67, P = 0.001) an increasing trend with increase in altitude. On average, the percentages of SOC at 0-10-, 10-20-, and 20-30-cm depths were 53.2, 26.5, and 20.3 %, respectively. Bulk density increased significantly with increase in soil depth and decreased with increase in altitude. Our results suggest that SOC stocks in temperate forests of Kashmir Himalaya vary greatly with forest type and altitude. The present study reveals that SOC stocks increased with increase in altitude at high mountainous regions. Climate change in these high mountainous regions will alter the carbon sequestration potential, which would affect the global carbon cycle.

40 CFR 89.112 - Oxides of nitrogen, carbon monoxide, hydrocarbon, and particulate matter exhaust emission standards.

Science.gov (United States)

2010-07-01

....112 Oxides of nitrogen, carbon monoxide, hydrocarbon, and particulate matter exhaust emission... emissions of oxides of nitrogen, carbon monoxide, hydrocarbon, and nonmethane hydrocarbon are measured using... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Oxides of nitrogen, carbon monoxide...

Fluidized bed electrodes with high carbon loading for water desalination by capacitive deionization

NARCIS (Netherlands)

Doornbusch, G.J.; Dykstra, J.E.; Biesheuvel, P.M.; Suss, M.E.

2016-01-01

The use of carbon flow electrodes has significantly impacted electrochemical energy storage and capacitive deionization (CDI), but device performance is limited as these electrodes cannot surpass ∼20 wt% carbon while maintaining flowability. We here introduce flowable fluidized bed electrodes

Observed 20th Century Desert Dust Variability: Impact on Climate and Biogeochemistry

Energy Technology Data Exchange (ETDEWEB)

Mahowald, Natalie [Cornell University; Kloster, Silvia [Cornell University; Engelstaedter, S. [Cornell University; Moore, Jefferson Keith [University of California, Irvine; Mukhopadhyay, S. [Harvard University; McConnell, J. R. [Desert Research Institute, Reno, NV; Albani, S. [Cornell University; Doney, Scott C. [Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA; Bhattacharya, A. [Harvard University; Curran, M. A. J. [Antarctic Climate and Ecosystems Cooperative Research Centre; Flanner, Mark G. [University of Michigan; Hoffman, Forrest M [ORNL; Lawrence, David M. [National Center for Atmospheric Research (NCAR); Lindsay, Keith [National Center for Atmospheric Research (NCAR); Mayewski, P. A. [University of Maine; Neff, Jason [University of Colorado, Boulder; Rothenberg, D. [Cornell University; Thomas, E. [British Antarctic Survey, Cambridge, UK; Thornton, Peter E [ORNL; Zender, Charlie S. [University of California, Irvine

2010-01-01

Desert dust perturbs climate by directly and indirectly interacting with incoming solar and outgoing long wave radiation, thereby changing precipitation and temperature, in addition to modifying ocean and land biogeochemistry. While we know that desert dust is sensitive to perturbations in climate and human land use, previous studies have been unable to determine whether humans were increasing or decreasing desert dust in the global average. Here we present observational estimates of desert dust based on paleodata proxies showing a doubling of desert dust during the 20th century over much, but not all the globe. Large uncertainties remain in estimates of desert dust variability over 20th century due to limited data. Using these observational estimates of desert dust change in combination with ocean, atmosphere and land models, we calculate the net radiative effect of these observed changes (top of atmosphere) over the 20th century to be -0.14 {+-} 0.11 W/m{sup 2} (1990-1999 vs. 1905-1914). The estimated radiative change due to dust is especially strong between the heavily loaded 1980-1989 and the less heavily loaded 1955-1964 time periods (-0.57 {+-} 0.46 W/m{sup 2}), which model simulations suggest may have reduced the rate of temperature increase between these time periods by 0.11 C. Model simulations also indicate strong regional shifts in precipitation and temperature from desert dust changes, causing 6 ppm (12 PgC) reduction in model carbon uptake by the terrestrial biosphere over the 20th century. Desert dust carries iron, an important micronutrient for ocean biogeochemistry that can modulate ocean carbon storage; here we show that dust deposition trends increase ocean productivity by an estimated 6% over the 20th century, drawing down an additional 4 ppm (8 PgC) of carbon dioxide into the oceans. Thus, perturbations to desert dust over the 20th century inferred from observations are potentially important for climate and biogeochemistry, and our understanding

Comparison of carbon sequestration potential in agricultural and afforestation farming systems

Directory of Open Access Journals (Sweden)

Chinsu Lin

2013-04-01

Full Text Available In the last few decades, many forests have been cut down to make room for cultivation and to increase food or energy crops production in developing countries. In this study, carbon sequestration and wood production were evaluated on afforested farms by integrating the Gaussian diameter distribution model and exponential diameter-height model derived from sample plots of an afforested hardwood forest in Taiwan. The quantity of sequestrated carbon was determined based on aboveground biomass. Through pilot tests run on an age-volume model, an estimation bias was obtained and used to correct predicted volume estimates for a farm forest over a 20-year period. An estimated carbon sequestration of 11,254 t C was observed for a 189ha-hardwood forest which is equivalent to 41,264 t CO2. If this amount of carbon dioxide were exchanged on the Chicago Climate Exchange (CCX market, the income earned would be 821 US$ ha- 1. Carbon sequestration from rice (Oryza sativa or sugarcane (Saccharum officinarum production is discharged as a result of straw decomposition in the soil which also improves soil quality. Sugarcane production does not contribute significantly to carbon sequestration, because almost all the cane fiber is used as fuel for sugar mills. As a result of changing the farming systems to hardwood forest in this study area, carbon sequestration and carbon storage have increased at the rate of 2.98 t C ha- 1 year- 1. Net present value of afforestation for a 20-year period of carbon or wood management is estimated at around US$ 30,000 given an annual base interest rate of 3 %.

Carbon nanofibers grafted on activated carbon as an electrode in high-power supercapacitors.

Science.gov (United States)

Gryglewicz, Grażyna; Śliwak, Agata; Béguin, François

2013-08-01

A hybrid electrode material for high-power supercapacitors was fabricated by grafting carbon nanofibers (CNFs) onto the surface of powdered activated carbon (AC) through catalytic chemical vapor deposition (CCVD). A uniform thin layer of disentangled CNFs with a herringbone structure was deposited on the carbon surface through the decomposition of propane at 450 °C over an AC-supported nickel catalyst. CNF coating was controlled by the reaction time and the nickel content. The superior CNF/AC composite displays excellent electrochemical performance in a 0.5 mol L(-1) solution of K2 SO4 due to its unique structure. At a high scan rate (100 mV s(-1) ) and current loading (20 A g(-1) ), the capacitance values were three- and fourfold higher than those for classical AC/carbon black composites. Owing to this feature, a high energy of 10 Wh kg(-1) was obtained over a wide power range in neutral medium at a voltage of 0.8 V. The significant enhancement of charge propagation is attributed to the presence of herringbone CNFs, which facilitate the diffusion of ions in the electrode and play the role of electronic bridges between AC particles. An in situ coating of AC with short CNFs (below 200 nm) is a very attractive method for producing the next generation of carbon composite materials with a high power performance in supercapacitors working in neutral medium. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Global Tree Cover and Biomass Carbon on Agricultural Land: The contribution of agroforestry to global and national carbon budgets.

Science.gov (United States)

Zomer, Robert J; Neufeldt, Henry; Xu, Jianchu; Ahrends, Antje; Bossio, Deborah; Trabucco, Antonio; van Noordwijk, Meine; Wang, Mingcheng

2016-07-20

Agroforestry systems and tree cover on agricultural land make an important contribution to climate change mitigation, but are not systematically accounted for in either global carbon budgets or national carbon accounting. This paper assesses the role of trees on agricultural land and their significance for carbon sequestration at a global level, along with recent change trends. Remote sensing data show that in 2010, 43% of all agricultural land globally had at least 10% tree cover and that this has increased by 2% over the previous ten years. Combining geographically and bioclimatically stratified Intergovernmental Panel on Climate Change (IPCC) Tier 1 default estimates of carbon storage with this tree cover analysis, we estimated 45.3 PgC on agricultural land globally, with trees contributing >75%. Between 2000 and 2010 tree cover increased by 3.7%, resulting in an increase of >2 PgC (or 4.6%) of biomass carbon. On average, globally, biomass carbon increased from 20.4 to 21.4 tC ha(-1). Regional and country-level variation in stocks and trends were mapped and tabulated globally, and for all countries. Brazil, Indonesia, China and India had the largest increases in biomass carbon stored on agricultural land, while Argentina, Myanmar, and Sierra Leone had the largest decreases.

The effects of carbon distribution and thickness on the lithium storage properties of carbon-coated SnO_2 hollow nanofibers

International Nuclear Information System (INIS)

Zhou, Huimin; Li, Zhiyong; Qiu, Yiping; Xia, Xin

2016-01-01

To alleviate the enormous volume change problem of tin-based anodes for lithium ion batteries (LIBs), carbon-coated tin dioxide (SnO_2) hollow nanofibers were prepared by means of single-spinneret electrospinning followed by calcination and hydrothermal treatment. By varying the concentration of glucose and the reaction time during the hydrothermal coating process, the final product with different carbon distribution and thickness could be obtained. Galvanostatic charge/discharge was carried out to evaluate them as potential anode materials for LIBs. It was shown that the main effect of carbon distribution was to control the capacity retention rate, and the carbon thickness played the important role in lithium insertion/extraction properties. The optimum composite nanofibers could be prepared with glucose concentration of 10 mg/ml and hydrothermal time of 20 h, the carbon content and the specific surface area of which were 26.15% and 29.4 m"2/g, respectively. And this anode with both the carbon core and deposited thin carbon skin was able to deliver a high reversible capacity of 704.6 mAhg"−"1 and the capacity retention could retain 68.2% after 80 cycles. - Graphical abstract: Based on the electrochemical properties of carbon-coated hollow SnO2 anodes, how the carbon distribution and carbon thickness affect their performance are disscussed in groups. - Highlights: • The hollow SnO_2 nanofibers were carbon-coated by hydrothermal process. • The controlled distribution and thickness of carbon layer can be obtained. • The main effect of carbon distribution was to control the capacity retention rate. • The carbon thickness played the important role in lithium insertion/extraction properties.

Accelerated Carbonation of Steel Slag Compacts: Development of High-Strength Construction Materials

Energy Technology Data Exchange (ETDEWEB)

Quaghebeur, Mieke; Nielsen, Peter, E-mail: peter.nielsen@vito.be; Horckmans, Liesbeth [Sustainable Materials Management, VITO, Mol (Belgium); Van Mechelen, Dirk [RECMIX bvba, Genk (Belgium)

2015-12-17

Mineral carbonation involves the capture and storage of carbon dioxide in carbonate minerals. Mineral carbonation presents opportunities for the recycling of steel slags and other alkaline residues that are currently landfilled. The Carbstone process was initially developed to transform non-hydraulic steel slags [stainless steel (SS) slag and basic oxygen furnace (BOF) slags] in high-quality construction materials. The process makes use of accelerated mineral carbonation by treating different types of steel slags with CO{sub 2} at elevated pressure (up to 2 MPa) and temperatures (20–140°C). For SS slags, raising the temperature from 20 to 140°C had a positive effect on the CO{sub 2} uptake, strength development, and the environmental properties (i.e., leaching of Cr and Mo) of the carbonated slag compacts. For BOF slags, raising the temperature was not beneficial for the carbonation process. Elevated CO{sub 2} pressure and CO{sub 2} concentration of the feed gas had a positive effect on the CO{sub 2} uptake and strength development for both types of steel slags. In addition, the compaction force had a positive effect on the strength development. The carbonates that are produced in situ during the carbonation reaction act as a binder, cementing the slag particles together. The carbonated compacts (Carbstones) have technical properties that are equivalent to conventional concrete products. An additional advantage is that the carbonated materials sequester 100–150 g CO{sub 2}/kg slag. The technology was developed on lab scale by the optimization of process parameters with regard to compressive strength development, CO{sub 2} uptake, and environmental properties of the carbonated construction materials. The Carbstone technology was validated using (semi-)industrial equipment and process conditions.

Geography of Global Forest Carbon Stocks & Dynamics

Science.gov (United States)

Saatchi, S. S.; Yu, Y.; Xu, L.; Yang, Y.; Fore, A.; Ganguly, S.; Nemani, R. R.; Zhang, G.; Lefsky, M. A.; Sun, G.; Woodall, C. W.; Naesset, E.; Seibt, U. H.

2014-12-01

Spatially explicit distribution of carbon stocks and dynamics in global forests can greatly reduce the uncertainty in the terrestrial portion of the global carbon cycle by improving estimates of emissions and uptakes from land use activities, and help with green house gas inventory at regional and national scales. Here, we produce the first global distribution of carbon stocks in living woody biomass at ~ 100 m (1-ha) resolution for circa 2005 from a combination of satellite observations and ground inventory data. The total carbon stored in live woody biomass is estimated to be 337 PgC with 258 PgC in aboveground and 79 PgC in roots, and partitioned globally in boreal (20%), tropical evergreen (50%), temperate (12%), and woodland savanna and shrublands (15%). We use a combination of satellite observations of tree height, remote sensing data on deforestation and degradation to quantify the dynamics of these forests at the biome level globally and provide geographical distribution of carbon storage dynamics in terms sinks and sources globally.

EFFECTS OF MINERAL ADMIXTURE ON THE CARBONIC ACID LEACHING RESISTANCE OF CEMENT-BASED MATERIALS

Directory of Open Access Journals (Sweden)

Yun Dong

2017-07-01

Full Text Available In order to reveal the degradation process and deterioration mechanism of cement-based materials, this paper analyzes the effects of carbonic acid leaching on the mechanical strength of mortars, as well as relative mass loss, microstructure, and composition of various cement pastes. The results indicate that cement pastes containing less than 20 % fly ash have higher carbonic acid leaching resistance than cement pastes without fly ash. However, after carbonic acid leaching, the compressive strength of the samples with fly ash is lower than that of the cement pastes without fly ash. The leaching resistance is good for samples cured at an early age before leaching. Carbonic acid leaching proceeds from the paste surface to the interior. The incorporation of an appropriate amount of slag powder helps to increase the density of the paste. Due to the pozzolanic activity of fly ash at late-stage leaching, a mixture of fly ash (≤ 20 % and slag powder (≤ 20 % effectively improves carbonic acid leaching resistance. The products of early-stage leaching were mainly CaCO₃ and small amounts of SiO₂ and Fe₂O₃. The C-S-H phase at the paste surface suffered serious damage after long periods of leaching, and the main products of leaching were SiO₂ and Fe₂O₃.

Economic Evaluations for the Carbon Dioxide-involved Production of High-value Chemicals

Energy Technology Data Exchange (ETDEWEB)

Lee, Ji Hyun; Lee, Dong Woog; Jang, Se Gyu; Kwak, No-Sang; Lee, In Young; Jang, Kyung Ryoung; Shim, Jae-Goo [KEPCO Research Institute, Daejon (Korea, Republic of); Choi, Jong Shin [Korea East-West Power Co. LTD, Seoul (Korea, Republic of)

2014-06-15

Economic evaluation of the manufacturing technology of high-value chemicals through the carbonation reaction of carbon dioxide contained in the flue gas was performed, and analysis of the IRR (Internal Rate of Return) and whole profit along the production plan of the final product was conducted. Through a carbonation reaction with sodium hydroxide that is generated from electrolysis and by using carbon dioxide in the combustion gas that is generated in the power plant, it is possible to get a high value products such as sodium bicarbonate compound and also to reduce the carbon dioxide emission simultaneously. The IRR (Internal Rate of Return) and NPV (Net Present Value) methods were used for the economic evaluation of the process which could handle carbon dioxide of 100 tons per day in the period of the 20 years of plant operation. The results of economic evaluation showed that the IRR of baseline case of technology was 67.2% and the profit that obtained during the whole operation period (20 years) was 346,922 million won based on NPV value. When considering ETS due to the emissions trading enforcement that will be activated in 2015, the NPV was improved to a 6,000 million won. Based on this results, it could be concluded that this CO2 carbonation technology is an cost-effective technology option for the reduction of greenhouse gas.

Economic Evaluations for the Carbon Dioxide-involved Production of High-value Chemicals

International Nuclear Information System (INIS)

Lee, Ji Hyun; Lee, Dong Woog; Jang, Se Gyu; Kwak, No-Sang; Lee, In Young; Jang, Kyung Ryoung; Shim, Jae-Goo; Choi, Jong Shin

2014-01-01

Economic evaluation of the manufacturing technology of high-value chemicals through the carbonation reaction of carbon dioxide contained in the flue gas was performed, and analysis of the IRR (Internal Rate of Return) and whole profit along the production plan of the final product was conducted. Through a carbonation reaction with sodium hydroxide that is generated from electrolysis and by using carbon dioxide in the combustion gas that is generated in the power plant, it is possible to get a high value products such as sodium bicarbonate compound and also to reduce the carbon dioxide emission simultaneously. The IRR (Internal Rate of Return) and NPV (Net Present Value) methods were used for the economic evaluation of the process which could handle carbon dioxide of 100 tons per day in the period of the 20 years of plant operation. The results of economic evaluation showed that the IRR of baseline case of technology was 67.2% and the profit that obtained during the whole operation period (20 years) was 346,922 million won based on NPV value. When considering ETS due to the emissions trading enforcement that will be activated in 2015, the NPV was improved to a 6,000 million won. Based on this results, it could be concluded that this CO2 carbonation technology is an cost-effective technology option for the reduction of greenhouse gas

Carbon foam/hydroxyapatite coating for carbon/carbon composites: Microstructure and biocompatibility

Energy Technology Data Exchange (ETDEWEB)

Zhang, Leilei, E-mail: zhangleilei1121@aliyun.com; Li, Hejun; Li, Kezhi; Zhang, Shouyang; Lu, Jinhua; Li, Wei; Cao, Sheng; Wang, Bin

2013-12-01

To improve the surface biocompatibility of carbon/carbon composites, a carbon foam/hydroxyapatite coating was applied using a combination method of slurry procedure and ultrasound-assisted electrochemical deposition procedure. The morphology, microstructure and chemical composition of the coating were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray diffraction. The biocompatibility of the carbon foam/hydroxyapatite coating was investigated by osteoblast-like MG63 cell culture tests. The results showed that the carbon foam could provide a large number of pores on the surface of carbon/carbon composites. The hydroxyapatite crystals could infiltrate into the pores and form the carbon foam/hydroxyapatite coating. The coating covered the carbon/carbon composites fully and uniformly with slice morphology. The cell response tests showed that the MG63 cells on carbon foam/hydroxyapatite coating had a better cell adhesion and cell proliferation than those on uncoated carbon/carbon composites. The carbon foam/hydroxyapatite coatings were cytocompatible and were beneficial to improve the biocompatibility. The approach presented here may be exploited for fabrication of carbon/carbon composite implant surfaces.

Carbon foam/hydroxyapatite coating for carbon/carbon composites: Microstructure and biocompatibility

International Nuclear Information System (INIS)

Zhang, Leilei; Li, Hejun; Li, Kezhi; Zhang, Shouyang; Lu, Jinhua; Li, Wei; Cao, Sheng; Wang, Bin

2013-01-01

To improve the surface biocompatibility of carbon/carbon composites, a carbon foam/hydroxyapatite coating was applied using a combination method of slurry procedure and ultrasound-assisted electrochemical deposition procedure. The morphology, microstructure and chemical composition of the coating were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray diffraction. The biocompatibility of the carbon foam/hydroxyapatite coating was investigated by osteoblast-like MG63 cell culture tests. The results showed that the carbon foam could provide a large number of pores on the surface of carbon/carbon composites. The hydroxyapatite crystals could infiltrate into the pores and form the carbon foam/hydroxyapatite coating. The coating covered the carbon/carbon composites fully and uniformly with slice morphology. The cell response tests showed that the MG63 cells on carbon foam/hydroxyapatite coating had a better cell adhesion and cell proliferation than those on uncoated carbon/carbon composites. The carbon foam/hydroxyapatite coatings were cytocompatible and were beneficial to improve the biocompatibility. The approach presented here may be exploited for fabrication of carbon/carbon composite implant surfaces.

Carbon exchange between ecosystems and atmosphere in the Czech Republic is affected by climate factors

International Nuclear Information System (INIS)

Marek, Michal V.; Janous, Dalibor; Taufarova, Klara; Havrankova, Katerina; Pavelka, Marian; Kaplan, Veroslav; Markova, Irena

2011-01-01

By comparing five ecosystem types in the Czech Republic over several years, we recorded the highest carbon sequestration potential in an evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). Because of a massive ecosystem respiration, the final carbon gain of the grassland was negative. Climate was shown to be an important factor of carbon uptake by ecosystems: by varying the growing season length (a 22-d longer season in 2005 than in 2007 increased carbon sink by 13%) or by the effect of short- term synoptic situations (e.g. summer hot and dry days reduced net carbon storage by 58% relative to hot and wet days). Carbon uptake is strongly affected by the ontogeny and a production strategy which is demonstrated by the comparison of seasonal course of carbon uptake between coniferous (Norway spruce) and deciduous (European beech) stands. - Highlights: → Highest carbon sequestration potential in evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). → The final carbon gain of the grassland was negative (massive ecosystem respiration). → Climate is important factor of net primary productivity. → Carbon uptake is strongly affected by the ontogeny and a production strategy of ecosystem. - Identification of the apparent differences in the carbon storage by different ecosystem types.

Microbially mediated mineral carbonation

Science.gov (United States)

Power, I. M.; Wilson, S. A.; Dipple, G. M.; Southam, G.

2010-12-01

implemented and economically efficient alternative to other technologies currently under development for mineral sequestration. Dismukes GC, Carrieri D, Bennette N, Ananyev GM, Posewitz MC (2008) Aquatic phototrophs: efficient alternatives to land-based crops for biofuels. Current Opinion in Biotechnology, 19, 235-240. Ferris FG, Wiese RG, Fyfe WS (1994) Precipitation of carbonate minerals by microorganisms: Implications of silicate weathering and the global carbon dioxide budget. Geomicrobiology Journal, 12, 1-13. Lackner KS, Wendt CH, Butt DP, Joyce EL, Jr., Sharp DH (1995) Carbon dioxide disposal in carbonate minerals. Energy, 20, 1153-1170. Power IM, Wilson SA, Thom JM, Dipple GM, Gabites JE, Southam G (2009) The hydromagnesite playas of Atlin, British Columbia, Canada: A biogeochemical model for CO2 sequestration. Chemical Geology, 206, 302-316. Thompson JB, Ferris FG (1990) Cyanobacterial precipitation of gypsum, calcite, and magnesite from natural alkaline lake water. Geology, 18, 995-998.

Novel polybenzoxazine-based carbon aerogel electrode for supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Katanyoota, Porawee [Petroleum and Petrochemical College and National Center of Excellence for Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University, Bangkok 10330 (Thailand); Chaisuwan, Thayanlak, E-mail: thanyalak.c@hotmail.co [Petroleum and Petrochemical College and National Center of Excellence for Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University, Bangkok 10330 (Thailand); Wongchaisuwat, Atchana [Department of Chemistry, Kasetsart University, Bangkok 10900 (Thailand); Wongkasemjit, Sujitra, E-mail: dsujitra@chula.ac.t [Petroleum and Petrochemical College and National Center of Excellence for Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University, Bangkok 10330 (Thailand)

2010-02-25

In this study, polybenzoxazine, a new high performance thermosetting resin, was used to prepare carbon aerogels used as an electrode for supercapacitors. Two types of polybenzoxazines, derived from two different amines, aniline and triethylenetetramine, and denoted as BA-a and BA-teta, respectively, were chosen as the reactants for the organic precursor preparation. The surface area of carbon aerogels from both BA-a and BA-teta was 391 and 368 m{sup 2}/g, respectively. The pore size of each carbon aerogel was in the range of 2-5 nm, which is a suitable pore size for use as electrodes in electrochemical applications. The electrochemical properties of the obtained carbon aerogels showed good performance for supercapacitor applications with a specific capacitance of 55.78 and 20.53 F/g for BA-teta and BA-a, respectively. At low voltage scanning, 1 and 5 mV/s, the cyclic voltammogram of the carbon aerogel derived from BA-teta gave a better rectangular shape than that of the other carbon aerogel. The impedance spectra of both carbon aerogels confirmed the results of the capacitance and the cyclic voltammogram analyses.

Novel polybenzoxazine-based carbon aerogel electrode for supercapacitors

International Nuclear Information System (INIS)

Katanyoota, Porawee; Chaisuwan, Thayanlak; Wongchaisuwat, Atchana; Wongkasemjit, Sujitra

2010-01-01

In this study, polybenzoxazine, a new high performance thermosetting resin, was used to prepare carbon aerogels used as an electrode for supercapacitors. Two types of polybenzoxazines, derived from two different amines, aniline and triethylenetetramine, and denoted as BA-a and BA-teta, respectively, were chosen as the reactants for the organic precursor preparation. The surface area of carbon aerogels from both BA-a and BA-teta was 391 and 368 m 2 /g, respectively. The pore size of each carbon aerogel was in the range of 2-5 nm, which is a suitable pore size for use as electrodes in electrochemical applications. The electrochemical properties of the obtained carbon aerogels showed good performance for supercapacitor applications with a specific capacitance of 55.78 and 20.53 F/g for BA-teta and BA-a, respectively. At low voltage scanning, 1 and 5 mV/s, the cyclic voltammogram of the carbon aerogel derived from BA-teta gave a better rectangular shape than that of the other carbon aerogel. The impedance spectra of both carbon aerogels confirmed the results of the capacitance and the cyclic voltammogram analyses.

Including carbon emissions from deforestation in the carbon footprint of Brazilian beef.

Science.gov (United States)

Cederberg, Christel; Persson, U Martin; Neovius, Kristian; Molander, Sverker; Clift, Roland

2011-03-01

Effects of land use changes are starting to be included in estimates of life-cycle greenhouse gas (GHG) emissions, so-called carbon footprints (CFs), from food production. Their omission can lead to serious underestimates, particularly for meat. Here we estimate emissions from the conversion of forest to pasture in the Legal Amazon Region (LAR) of Brazil and present a model to distribute the emissions from deforestation over products and time subsequent to the land use change. Expansion of cattle ranching for beef production is a major cause of deforestation in the LAR. The carbon footprint of beef produced on newly deforested land is estimated at more than 700 kg CO(2)-equivalents per kg carcass weight if direct land use emissions are annualized over 20 years. This is orders of magnitude larger than the figure for beef production on established pasture on non-deforested land. While Brazilian beef exports have originated mainly from areas outside the LAR, i.e. from regions not subject to recent deforestation, we argue that increased production for export has been the key driver of the pasture expansion and deforestation in the LAR during the past decade and this should be reflected in the carbon footprint attributed to beef exports. We conclude that carbon footprint standards must include the more extended effects of land use changes to avoid giving misleading information to policy makers, retailers, and consumers.

Gas flaring: Carbon dioxide contribution to global warming ...

African Journals Online (AJOL)

Journal Home > Vol 20, No 2 (2016) > ... The quantitative method of analysis showed that carbon dioxide from gas ... gas flaring cause environmental degradation, health risks and constitute financial loss to the local oil producing communities.

Procedure for coating articles with pyrolytic carbon

International Nuclear Information System (INIS)

Adams, C.C.; Allen, C.L.; Besenbruch, G.E.A.

1976-01-01

A method to coat articles with pyrolytic carbon is described which is particularly suitable for small nuclear fuel particles as one obtains a very homogeneous layer. The pyrolytic carbon is produced according to the invention by decomposing a hydrocarbon gas mixture composed of an inert gas share (20-65 Vol%) and a mixture of acetylene and propylene. It is favourable to have the hydrocarbon mixture contain between 50 and 55 Vol% acetylene. Variations on the known procedure are given. The coating of spherical thorium dioxide particles is mentioned as an example. (UWI) [de

Patterned functional carbon fibers from polyethylene

Energy Technology Data Exchange (ETDEWEB)

Hunt, Marcus A [ORNL; Saito, Tomonori [ORNL; Brown, Rebecca H [ORNL; Kumbhar, Amar S [University of North Carolina, Chapel Hill; Naskar, Amit K [ORNL

2012-01-01

Patterned, continuous carbon fibers with controlled surface geometry were produced from a novel melt-processible carbon precursor. This portends the use of a unique technique to produce such technologically innovative fibers in large volume for important applications. The novelties of this technique include ease of designing and fabricating fibers with customized surface contour, the ability to manipulate filament diameter from submicron scale to a couple of orders of magnitude larger scale, and the amenable porosity gradient across the carbon wall by diffusion controlled functionalization of precursor. The geometry of fiber cross-section was tailored by using bicomponent melt-spinning with shaped dies and controlling the melt-processing of the precursor polymer. Circular, trilobal, gear-shaped hollow fibers, and solid star-shaped carbon fibers of 0.5 - 20 um diameters, either in self-assembled bundle form, or non-bonded loose filament form, were produced by carbonizing functionalized-polyethylene fibers. Prior to carbonization, melt-spun fibers were converted to a char-forming mass by optimizing the sulfonation on polyethylene macromolecules. The fibers exhibited distinctly ordered carbon morphologies at the outside skin compared to the inner surface or fiber core. Such order in carbon microstructure can be further tuned by altering processing parameters. Partially sulfonated polyethylene-derived hollow carbon fibers exhibit 2-10 fold surface area (50-500 m2/g) compared to the solid fibers (10-25 m2/g) with pore sizes closer to the inside diameter of the filaments larger than the sizes on the outer layer. These specially functionalized carbon fibers hold promise for extraordinary performance improvements when used, for example, as composite reinforcements, catalyst support media, membranes for gas separation, CO2 sorbents, and active electrodes and current collectors for energy storage applications.

Carbon-climate feedbacks accelerate ocean acidification

Science.gov (United States)

Matear, Richard J.; Lenton, Andrew

2018-03-01

Carbon-climate feedbacks have the potential to significantly impact the future climate by altering atmospheric CO2 concentrations (Zaehle et al. 2010). By modifying the future atmospheric CO2 concentrations, the carbon-climate feedbacks will also influence the future ocean acidification trajectory. Here, we use the CO2 emissions scenarios from four representative concentration pathways (RCPs) with an Earth system model to project the future trajectories of ocean acidification with the inclusion of carbon-climate feedbacks. We show that simulated carbon-climate feedbacks can significantly impact the onset of undersaturated aragonite conditions in the Southern and Arctic oceans, the suitable habitat for tropical coral and the deepwater saturation states. Under the high-emissions scenarios (RCP8.5 and RCP6), the carbon-climate feedbacks advance the onset of surface water under saturation and the decline in suitable coral reef habitat by a decade or more. The impacts of the carbon-climate feedbacks are most significant for the medium- (RCP4.5) and low-emissions (RCP2.6) scenarios. For the RCP4.5 scenario, by 2100 the carbon-climate feedbacks nearly double the area of surface water undersaturated with respect to aragonite and reduce by 50 % the surface water suitable for coral reefs. For the RCP2.6 scenario, by 2100 the carbon-climate feedbacks reduce the area suitable for coral reefs by 40 % and increase the area of undersaturated surface water by 20 %. The sensitivity of ocean acidification to the carbon-climate feedbacks in the low to medium emission scenarios is important because recent CO2 emission reduction commitments are trying to transition emissions to such a scenario. Our study highlights the need to better characterise the carbon-climate feedbacks and ensure we do not underestimate the projected ocean acidification.

Heavy metal ion adsorption onto polypyrrole-impregnated porous carbon.

Science.gov (United States)

Choi, Moonjung; Jang, Jyongsik

2008-09-01

Polypyrrole-impregnated porous carbon was readily synthesized using vapor infiltration polymerization of pyrrole monomers. The results show that the functionalized polymer layer was successfully coated onto the pore surface of carbon without collapse of mesoporous structure. The modified porous carbon exhibited an improved complexation affinity for heavy metal ions such as mercury, lead, and silver ions due to the amine group of polypyrrole. The introduced polypyrrole layer could provide the surface modification to be applied for heavy metal ion adsorbents. Especially, polymer-impregnated porous carbon has an enhanced heavy metal ion uptake, which is 20 times higher than that of adsorbents with amine functional groups. Furthermore, the relationship between the coated polymer amount and surface area was also investigated in regard to adsorption capacity.

Preparation of carbon-free TEM microgrids by metal sputtering

Energy Technology Data Exchange (ETDEWEB)

Janbroers, S., E-mail: stephan.janbroers@albemarle.com [Albemarle Catalysts B.V., Nieuwendammerkade 1-3, 1030 BE, Amsterdam (Netherlands); Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Kruijff, T.R. de; Xu, Q. [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Kooyman, P.J. [DelftChemTech, Delft University of Technology, Julianalaan 136, 2628 BL, Delft (Netherlands); Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Zandbergen, H.W. [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands)

2009-08-15

A new method for preparing carbon-free, temperature-stable Transmission Electron Microscope (TEM) grids is presented. An 80% Au/20% Pd metal film is deposited onto a 'holey' microgrid carbon supported on standard mixed-mesh Au TEM grids. Subsequently, the carbon film is selectively removed using plasma cleaning. In this way, an all-metal TEM film is made containing the 'same' microgrid as the original carbon film. Although electron transparency of the foil is reduced significantly, the open areas for TEM inspection of material over these areas are maintained. The metal foil can be prepared with various thicknesses and ensures good electrical conductivity. The new Au/Pd grids are stable to at least 775 K under vacuum conditions.

Electrochemical properties of Super P carbon black as an anode active material for lithium-ion batteries

International Nuclear Information System (INIS)

Gnanamuthu, RM.; Lee, Chang Woo

2011-01-01

Highlights: → A novel attempt of Super P carbon black as an anode active material for lithium-ion batteries. → The first discharge capacity was approximately 1256 mAh g -1 and at the end of 20th cycling the capacity was 610 mAh g -1 at 0.1 C rate. → Coulombic efficiency of Super P carbon black electrode was maintained about 84% at the end of cycling. - Abstract: A new approach to investigate upon the electrochemical properties of Super P carbon black anode material is attempted and compared with conventional mesophase pitch-based carbon fibers (MPCFs) anode material for lithium-ion batteries. The prepared Super P carbon black electrodes are characterized using transmission electron microscope (TEM). The assembled 2032-type coin cells are electrochemically characterized by ac impedance spectroscopic and cyclic voltammetric methods. The electrochemical performance of charge and discharge was analyzed using a battery cycler at 0.1 C rate and cut-off potentials of 1.20 and 0.01 V vs. Li/Li + . The electrochemical test illustrates that the discharge capacity corresponding to Li intercalation into the Super P carbon black electrode is higher and coulombic efficiency is maintained approximately 84% at the end of the 20th cycling at room temperature.

Hydrogenation of surface carbon on alumina-supported nickel

Energy Technology Data Exchange (ETDEWEB)

Mccarthy, J.G.; Wise, H.

1979-05-01

The methanation of carbon deposited by CO or ethylene decomposition on Girdler G-65 catalyst (25Vertical Bar3< nickel, 8Vertical Bar3< alkali, mostly CaO, 4Vertical Bar3< C as graphite, on alumina) was studied by temperature-programed desorption and temperature-programed surface reaction. Four types of carbon were identified: ..cap alpha..-carbon consisted of isolated carbon atoms bonded to nickel and reacting with hydrogen at 470/sup 0/ +/- 20/sup 0/K; ..gamma..-carbon was probably a bulk carbide, most likely Ni/sub 3/C, which had a reaction peak at 550/sup 0/K; ..beta..-carbon consisted of amorphous, polymerized carbon, which had a reaction peak at 680/sup 0/K; and an unreactive crystalline graphite-like species. The ..cap alpha..-form was thermally unstable and transformed into the ..beta..-form above 600/sup 0/K. Both ..cap alpha..- and ..beta..-forms slowly converted to inert graphite above 600/sup 0/K. The evidence suggested that synthesis gas methanation proceeds by dissociative adsorption of CO as the rate-determining step which forms a very reactive carbon adatom state (..cap alpha..') which converts to the ..cap alpha..-state in the absence of hydrogen and to methane in the presence of hydrogen.

Gas chromatographic method fr determination of carbon in metallic uranium

International Nuclear Information System (INIS)

Nikol'skij, V.A.; Markov, V.K.; Evseeva, T.I.; Cherstvenkova, E.P.

1983-01-01

Gas chromatographic device to determine carbon in metal uranium is developed. Burnout unite, permitting to load in the burnout tube simultaneously quite a few (up to 20) weight amounts of materials to be burned is a characteristic feature of the device. As a result amendments for control experiment and determination limit are decreased. The time of a single determination is also reduced. Conditions of carbon burn out from metal uranium are studied and temperature and time of complete extraction of carbon in the form of dioxide from weight amount into gaseous phase are established

Estimating Carbon Dynamics in an Intact Lowland Mixed Dipterocarp Forest Using a Forest Carbon Model

Directory of Open Access Journals (Sweden)

Jongyeol Lee

2017-04-01

Full Text Available Intact dipterocarp forests in Asia act as crucial carbon (C reservoirs, and it is therefore important to investigate the C dynamics in these forests. We estimated C dynamics, together with net ecosystem production (NEP, in an intact tropical dipterocarp forest of Brunei Darussalam. Fifty-four simulation units (plots; 20 m × 20 m were established and initial C stocks were determined via direct field measurement. The C dynamics were annually simulated with a regression model and the Forest Biomass and Dead organic matter Carbon (FBDC model. The initial C stock (Mg C·ha−1 of biomass, litter, dead wood and mineral soil were 213.1 ± 104.8, 2.0 ± 0.8, 31.3 ± 38.8, and 80.7 ± 15.5, respectively. Their annual changes (Mg C·ha−1·year−1 were 3.2 ± 1.1, 0.2 ± 0.2, −3.7 ± 6.1, and −0.3 ± 1.1, respectively. NEP was −0.6 ± 6.1 Mg C·ha−1·year−1, showing large heterogeneity among the plots. The initial C stocks of biomass and dead wood, biomass turnover rates and dead wood decay rates were elucidated as dominant factors determining NEP in a sensitivity analysis. Accordingly, investigation on those input data can constrain an uncertainty in determining NEP in the intact tropical forests.

The Air-Carbon-Water Synergies and Trade-Offs in China's Natural Gas Industry

Science.gov (United States)

Qin, Yue

China's coal-dominated energy structure is partly responsible for its domestic air pollution, local water stress, and the global climate change. Primarily to tackle the haze issue, China has been actively promoting a nationwide coal to natural gas end-use switch. My dissertation focuses on evaluating the air quality, carbon, and water impacts and their interactions in China's natural gas industry. Chapter 2 assesses the lifecycle climate performance of China's shale gas in comparison to coal based on stage-level energy consumption and methane leakage rates. I find the mean lifecycle carbon footprint of shale gas is about 30-50% lower than that of coal under both 20 year and 100 year global warming potentials (GWP20 and GWP100). However, primarily due to large uncertainties in methane leakage, the lifecycle carbon footprint of shale gas in China could be 15-60% higher than that of coal across sectors under GWP20. Chapter 3 evaluates the air quality, human health, and the climate impacts of China's coal-based synthetic natural gas (SNG) development. Based on earlier 2020 SNG production targets, I conduct an integrated assessment to identify production technologies and end-use applications that will bring as large air quality and health benefits as possible while keeping carbon penalties as small as possible. I find that, due to inefficient and uncontrolled coal combustion in households, allocating currently available SNG to the residential sector proves to be the best SNG allocation option. Chapter 4 compares the air quality, carbon, and water impacts of China's six major gas sources under three end-use substitution scenarios, which are focused on maximizing air pollutant emission reductions, CO 2 emission reductions, and water stress index (WSI)-weighted water consumption reductions, respectively. I find striking national air-carbon/water trade-offs due to SNG, which also significantly increases water demands and carbon emissions in regions already suffering from

Carbon dioxide in carbonated beverages induces ghrelin release and increased food consumption in male rats: Implications on the onset of obesity.

Science.gov (United States)

Eweis, Dureen Samandar; Abed, Fida; Stiban, Johnny

The dangerous health risks associated with obesity makes it a very serious public health issue. Numerous studies verified a correlation between the increase in obesity and the parallel increase in soft drink consumption among world populations. The effects of one main component in soft drinks namely the carbon dioxide gas has not been studied thoroughly in any previous research. Male rats were subjected to different categories of drinks and evaluated for over a year. Stomach ex vivo experiments were undertaken to evaluate the amount of ghrelin upon different beverage treatments. Moreover, 20 male students were tested for their ghrelin levels after ingestion of different beverages. Here, we show that rats consuming gaseous beverages over a period of around 1 year gain weight at a faster rate than controls on regular degassed carbonated beverage or tap water. This is due to elevated levels of the hunger hormone ghrelin and thus greater food intake in rats drinking carbonated drinks compared to control rats. Moreover, an increase in liver lipid accumulation of rats treated with gaseous drinks is shown opposed to control rats treated with degassed beverage or tap water. In a parallel study, the levels of ghrelin hormone were increased in 20 healthy human males upon drinking carbonated beverages compared to controls. These results implicate a major role for carbon dioxide gas in soft drinks in inducing weight gain and the onset of obesity via ghrelin release and stimulation of the hunger response in male mammals. Copyright © 2017 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

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

2009-01-01

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 50 mg NO 3 - -N/L

Financial risk and the transition to a low-carbon economy. Towards a carbon stress testing framework - Working Paper

International Nuclear Information System (INIS)

Chenet, Hugues; Thomae, Jakob; Janci, Didier; Dupre, Stan; Hubert, Romain; Robins, Nick; Cruickshank, Peter

2015-07-01

On July 27 at Moody's in New York, 2 deg. Investing Initiative launched the report 'Financial risk and the transition to a low-carbon economy' in partnership with UNEP Inquiry and I4CE. The report reviews the main approaches to assessing carbon risk along the investment chain and discusses barriers to its integration in decision making. The report identifies two categories of climate-related financial risks to financial institutions: risks arising from physical climate change and 'carbon risk' which arise from the transition to a low-carbon economy following one of the possible decarbonization pathways. The authors show that to date, risk factors resulting from climate change and the transition to a low-carbon economy are generally not taken into consideration by mainstream risk assessment and management frameworks; there are multiple reasons for this. The report reviews a number of 'climate and carbon stress test' initiatives that suggest the materiality of these risks along the investment chain. The materiality of these risks for financial institutions and the financial system remains unclear. Financial regulators and policy makers, notably in France, the United Kingdom, and at the G20 level have nevertheless started responding to the issue

Controllable synthesis of mesoporous carbon nanospheres and Fe-N/carbon nanospheres as efficient oxygen reduction electrocatalysts

Science.gov (United States)

Wei, Jing; Liang, Yan; Zhang, Xinyi; Simon, George P.; Zhao, Dongyuan; Zhang, Jin; Jiang, Sanping; Wang, Huanting

2015-03-01

The synthesis of mesoporous carbon nanospheres (MCNs), especially with diameters below 200 nm remains a great challenge due to weak interactions between the carbon precursors and soft templates, as well as the uncontrollable cross-linking rate of carbon precursors. Herein, we demonstrate a simple acid-assisted, hydrothermal synthesis approach to synthesizing such uniform MCNs with well controlled diameters ranging from 20 to 150 nm under highly acidic conditions (2 M HCl). Both the carbon precursor and the template are partly protonated under such conditions and show additional Coulombic interactions with chloride ions (acts as mediators). This kind of enhanced interaction is similar to that of the ``I+X-S+'' mechanism in the synthesis of mesoporous metal oxide, which can effectively retard the cross-linking rate of resol molecules and avoid macroscopic phase separation during the hydrothermal synthesis. Due to their uniform spherical morphology, small diameter, and high surface areas, MCNs can be modified with Fe and N species via impregnation of cheap precursors (ferric nitrate and dicyandiamide), which are further converted into nonprecious electrocatalysts for oxygen reduction reactions. The resulting Fe-N/MCNs exhibit high catalytic activities, long-term stability and improved methanol tolerance under alkaline conditions, which can be potentially used in direct methanol fuel cells and metal-air batteries.The synthesis of mesoporous carbon nanospheres (MCNs), especially with diameters below 200 nm remains a great challenge due to weak interactions between the carbon precursors and soft templates, as well as the uncontrollable cross-linking rate of carbon precursors. Herein, we demonstrate a simple acid-assisted, hydrothermal synthesis approach to synthesizing such uniform MCNs with well controlled diameters ranging from 20 to 150 nm under highly acidic conditions (2 M HCl). Both the carbon precursor and the template are partly protonated under such conditions

Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation

Science.gov (United States)

Schobben, Martin; van de Velde, Sebastiaan; Gliwa, Jana; Leda, Lucyna; Korn, Dieter; Struck, Ulrich; Vinzenz Ullmann, Clemens; Hairapetian, Vachik; Ghaderi, Abbas; Korte, Christoph; Newton, Robert J.; Poulton, Simon W.; Wignall, Paul B.

2017-11-01

Bulk-carbonate carbon isotope ratios are a widely applied proxy for investigating the ancient biogeochemical carbon cycle. Temporal carbon isotope trends serve as a prime stratigraphic tool, with the inherent assumption that bulk micritic carbonate rock is a faithful geochemical recorder of the isotopic composition of seawater dissolved inorganic carbon. However, bulk-carbonate rock is also prone to incorporate diagenetic signals. The aim of the present study is to disentangle primary trends from diagenetic signals in carbon isotope records which traverse the Permian-Triassic boundary in the marine carbonate-bearing sequences of Iran and South China. By pooling newly produced and published carbon isotope data, we confirm that a global first-order trend towards depleted values exists. However, a large amount of scatter is superimposed on this geochemical record. In addition, we observe a temporal trend in the amplitude of this residual δ13C variability, which is reproducible for the two studied regions. We suggest that (sub-)sea-floor microbial communities and their control on calcite nucleation and ambient porewater dissolved inorganic carbon δ13C pose a viable mechanism to induce bulk-rock δ13C variability. Numerical model calculations highlight that early diagenetic carbonate rock stabilization and linked carbon isotope alteration can be controlled by organic matter supply and subsequent microbial remineralization. A major biotic decline among Late Permian bottom-dwelling organisms facilitated a spatial increase in heterogeneous organic carbon accumulation. Combined with low marine sulfate, this resulted in varying degrees of carbon isotope overprinting. A simulated time series suggests that a 50 % increase in the spatial scatter of organic carbon relative to the average, in addition to an imposed increase in the likelihood of sampling cements formed by microbial calcite nucleation to 1 out of 10 samples, is sufficient to induce the observed signal of carbon

Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation

Directory of Open Access Journals (Sweden)

M. Schobben

2017-11-01

Full Text Available Bulk-carbonate carbon isotope ratios are a widely applied proxy for investigating the ancient biogeochemical carbon cycle. Temporal carbon isotope trends serve as a prime stratigraphic tool, with the inherent assumption that bulk micritic carbonate rock is a faithful geochemical recorder of the isotopic composition of seawater dissolved inorganic carbon. However, bulk-carbonate rock is also prone to incorporate diagenetic signals. The aim of the present study is to disentangle primary trends from diagenetic signals in carbon isotope records which traverse the Permian–Triassic boundary in the marine carbonate-bearing sequences of Iran and South China. By pooling newly produced and published carbon isotope data, we confirm that a global first-order trend towards depleted values exists. However, a large amount of scatter is superimposed on this geochemical record. In addition, we observe a temporal trend in the amplitude of this residual δ13C variability, which is reproducible for the two studied regions. We suggest that (sub-sea-floor microbial communities and their control on calcite nucleation and ambient porewater dissolved inorganic carbon δ13C pose a viable mechanism to induce bulk-rock δ13C variability. Numerical model calculations highlight that early diagenetic carbonate rock stabilization and linked carbon isotope alteration can be controlled by organic matter supply and subsequent microbial remineralization. A major biotic decline among Late Permian bottom-dwelling organisms facilitated a spatial increase in heterogeneous organic carbon accumulation. Combined with low marine sulfate, this resulted in varying degrees of carbon isotope overprinting. A simulated time series suggests that a 50 % increase in the spatial scatter of organic carbon relative to the average, in addition to an imposed increase in the likelihood of sampling cements formed by microbial calcite nucleation to 1 out of 10 samples, is sufficient to induce the

A cost–benefit analysis of the EU 20/20/2020 package

International Nuclear Information System (INIS)

Tol, Richard S.J.

2012-01-01

The European Commission did not publish a cost–benefit analysis for its 2020 climate package. This paper fills that gap, comparing the marginal costs and benefits of greenhouse gas emission reduction. The uncertainty about the marginal costs of climate change is large and skewed, and estimates partly reflect ethical choices (e.g., the discount rate). The 2010 carbon price in the EU Emissions Trading System can readily be justified by a cost–benefit analysis. Emission reduction is not expensive provided that policy is well-designed, a condition not met by planned EU policy. It is probably twice as expensive as needed, costing one in ten years of economic growth. The EU targets for 2020 are unlikely to meet the benefit–cost test. For a standard discount rate (3% pure rate of time preference), the benefit–cost ratio is rather poor (1/30)—so that benefits need to be very much higher, or costs very much lower than typically assumed to justify the 2020 targets. Only a very low discount rate (0% PRTP) would justify the 20% emission reduction target for 2020. - Highlights: ► First cost–benefit analysis of EU climate policy for 2020. ► Current carbon price in ETS can readily be justified by CBA. ► Emission targets for 2020 cannot be supported unless a low discount rate is chosen.

Ultraviolet modification of Chlamydomonas reinhardtii for carbon capture

Directory of Open Access Journals (Sweden)

Gopal NS

2016-04-01

Full Text Available Nikhil S Gopal,1 K Sudhakar2 1The Lawrenceville School, Lawrenceville, NJ, USA; 2Bioenergy Laboratory, Malauna Azad National Institute of Technology, Bhopal, India Purpose: Carbon dioxide (CO2 levels have been rising rapidly. Algae are single-cell organisms with highly efficient CO2 uptake mechanisms. Algae yield two to ten times more biomass versus terrestrial plants and can grow nearly anywhere. Large scale CO2 sequestration is not yet sustainable due to high amounts of nitrogen (N and phosphate (P needed to grow algae in media. Methods: Mutant strains of Chlamydomonas reinhardtii were created using ultraviolet light (2.2–3 K J/m2 and natural selection using media with 20%–80% lower N and P compared to standard Sueoka's high salt medium. Strains were selected based upon growth in media concentrations varying from 20% to 80% less N/P compared to control. Biomass was compared to wild-type control (CC-125 using direct counts, optical density dry weight, and mean doubling time. Results: Mean doubling time was 20 and 25 hours in the low N and N/P strains, respectively (vs 66 hours in control. Using direct counts, growth rates of mutant strains of low N and N/P cultures were not statistically different from control (P=0.37 and 0.70, respectively. Conclusion: Two new strains of algae, as well as wild-type control, were able to grow while using 20%–40% less N and P. Ultraviolet light-based modification of algae is an inexpensive and alternative option to genetic engineering techniques. This technique might make larger scale biosequestration possible. Keywords: biosequestration, ultraviolet, carbon sequestration, carbon capture, algae

Etching processes of transparent carbon nanotube thin films using laser technologies

International Nuclear Information System (INIS)

Lin, H.K.; Lin, R.C.; Li, C.H.

2010-01-01

Carbon nanotubes (CNTs) have potential as a transparent conductive material with good mechanical and electrical properties. However, carbon nanotube thin film deposition and etching processes are very difficult to pattern the electrode. In this study, transparent CNT film with a binder is coated on a PET flexible substrate. The transmittance and sheet resistance of carbon nanotube film are 84% and 1000 Ω/□, respectively. The etching process of carbon nanotube film on flexible substrates was investigated using 355 nm and 1064 nm laser sources. Experimental results show that carbon nanotube film can be ablated using laser technology. With the 355 nm UV laser, the minimum etched line width was 20 μm with a low amount of recast material of the ablated sections. The optimal conditions of laser ablation were determined for carbon nanotube film.

Reducing biomass recalcitrance via mild sodium carbonate pretreatment.

Science.gov (United States)

Mirmohamadsadeghi, Safoora; Chen, Zhu; Wan, Caixia

2016-06-01

This study examined the effects of mild sodium carbonate (Na2CO3) pretreatment on enzymatic hydrolysis of different feedstocks (i.e., corn stover, Miscanthus, and switchgrass). The results showed that sodium carbonate pretreatment markedly enhanced the sugar yields of the tested biomass feedstocks. The pretreated corn stover, Miscanthus, and switchgrass gave the glucose yields of 95.1%, 62.3%, and 81.3%, respectively, after enzymatic hydrolysis. The above glucose yields of pretreated feedstocks were 2-4 times that of untreated ones. The pretreatment also enhanced the xylose yields, 4 times for corn stover and 20 times for both Miscanthus and switchgrass. Sodium carbonate pretreatment removed 40-59% lignin from the tested feedstocks while preserving most of cellulose (sodium carbonate pretreatment was effective for reducing biomass recalcitrance and subsequently improving the digestibility of lignocellulosic biomass. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improved fatigue behavior of low-carbon steel 20GL by applying ultrasonic impact treatment combined with the electric discharge surface alloying

Energy Technology Data Exchange (ETDEWEB)

Mordyuk, B.N., E-mail: mordyuk@imp.kiev.ua [Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky blvd., UA-03142, Kyiv (Ukraine); Prokopenko, G.I.; Volosevich, P.Yu. [Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky blvd., UA-03142, Kyiv (Ukraine); Matokhnyuk, L.E.; Byalonovich, A.V. [Pisarenko Institute for Strength of Materials, NAS of Ukraine, 2 Timiryazevs’ka str., UA-01014, Kyiv (Ukraine); Popova, T.V. [Ukrainian Research Institute Rail carriage building, 33 Prikhodko str., UA-39621, Kremenchuk (Ukraine)

2016-04-06

The effects of severe plastic deformation induced by ultrasonic impact treatment (UIT) and the electric discharge surface alloying (EDSA) with chromium on the stress-controlled fatigue response of low-carbon steel 20GL are studied. The surface microrelief and integrity were analyzed using light microscopy and scanning electron microscopy (SEM). The structural formations in the sub-surface layers were characterized by means of X-ray diffraction analysis and transmission electron microscopy (TEM). The steel specimens underwent UIT, and complex UIT+EDSA and UIT+EDSA+UIT processes demonstrate the fatigue strength magnitudes increased respectively by ~15, ~5 and ~30% on the base of 10{sup 7} cycles in comparison with that for the pristine specimen. SEM analysis of fracture surfaces reveals the subsurface crack nucleation in the UIT-processed specimens instead of superficial crack initiation observed in the pristine and EDSA-processed ones. TEM studies demonstrate that a dislocation-cell structure forms in ferrite grains and partial dissolution of cementite occurs in pearlite grains both at the surface after UIT and in the layer at a depth of 15–25 µm after the UIT+EDSA+UIT process. The enhanced fatigue strength and prolonged lifetime of the low-carbon steel specimens after UIT and UIT+EDSA+UIT processes are concluded to be associated with the subsurface crack nucleation achieved by the following factors: (i) minimized surface roughness and improved integrity of the modified layer; (ii) compressive residual stresses; and (iii) surface hardening coupled with the alloying by chromium and with the formation of the dislocation-cell structure containing the cell walls impenetrable to moving dislocations at cyclic loading.

Improved corrosion resistance of cast carbon steel in sulphur oxides by Alonizing

International Nuclear Information System (INIS)

Holtzer, M.; Dzioba, Z.

1992-01-01

The results of studies on the Alonizing of cast steel and of testing the corrosion resistance of this cast steel in an atmosphere containing 5 to 6% SO 2 + 50% SO 3 at 853 K are described and compared with the results obtained with unalonized cast carbon steel and high-alloy 23Cr-8Ni-2Mo cast steel. The duration of the corrosion tests was 336 hours. The aluminium diffusion layer on cast carbon steel was obtained by holding the specimens in a mixture containing 99% of powered Fe-Al and 1% of NH 4 Cl at 1323 ± 20 K. The holding time was 10 and 20 hours, respectively. The aluminium layer formed on the cast carbon steel was examined by optical microscopy and an X-ray microanalysis. After Alonizing for 10 h the layer had reached a thickness of 950 μm, and contained up to 35% Al. In a mixture of sulphur oxides corrosion rate of the alonized cast carbon steel was by about 600 times lower than of the unalonized cast carbon steel, and by about 50 times lower than that of the 23Cr-8Ni-2Mo cast steel. (orig.) [de

A study of point defects created by electron irradiation of dilute iron-carbon alloys; Etude des defauts crees par irradiation electronique dans les alliages de fer carbone dilues

Energy Technology Data Exchange (ETDEWEB)

Leveque, J L [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1969-10-01

Resistivity and magnetic after effect (m.a.e.) measurements are used to study the influence of carbon atoms on the annealing process of point defects created by electron irradiation (3 MeV) at low temperature (20 deg. K). The presence of the carbon atoms has a strong influence on the recovery sub-stage I{sub E} and stage III. For the former, the carbon impurity traps the freely migrating iron interstitial. For the latter the effect is interpreted as being due to formation during annealing, of a carbon vacancy pair. A pronounced m.a.e. band is attributed to the reorientation of this carbon vacancy complex. All these results are coherent with the interpretation of a low temperature migrating free interstitial. (author) [French] L'influence des atomes de carbone sur le recuit des defauts ponctuels crees par irradiation electronique (3 MeV) a basse temperature (20 deg. K) dans le fer est mise en evidence par des mesures de resistivite electrique, et de trainage magnetique. Cette influence se manifeste principalement au cours du sous stade I{sub E} et du stade III de resistivite. Au sous stade I{sub E} les atomes de carbone piegeraient les interstitiels libres de fer au cours de leur migration. Le stade III est interprete comme etant du a la recombinaison du carbone dans les lacunes. Une importante bande de tramage magnetique etant attribuee a la reorientation de ce complexe. Ces resultats sont coherents avec l'interpretation faisant migrer a basse temperature l'interstitiel libre. (auteur)

Diiridium Bimetallic Complexes Function as a Redox Switch To Directly Split Carbonate into Carbon Monoxide and Oxygen.

Science.gov (United States)

Chen, Tsun-Ren; Wu, Fang-Siou; Lee, Hsiu-Pen; Chen, Kelvin H-C

2016-03-23

A pair of diiridium bimetallic complexes exhibit a special type of oxidation-reduction reaction that could directly split carbonate into carbon monoxide and molecular oxygen via a low-energy pathway needing no sacrificial reagent. One of the bimetallic complexes, Ir(III)(μ-Cl)2Ir(III), can catch carbonato group from carbonate and reduce it to CO. The second complex, the rare bimetallic complex Ir(IV)(μ-oxo)2Ir(IV), can react with chlorine to release O2 by the oxidation of oxygen ions with synergistic oxidative effect of iridium ions and chlorine atoms. The activation energy needed for the key reaction is quite low (∼20 kJ/mol), which is far less than the dissociation energy of the C═O bond in CO2 (∼750 kJ/mol). These diiridium bimetallic complexes could be applied as a redox switch to split carbonate or combined with well-known processes in the chemical industry to build up a catalytic system to directly split CO2 into CO and O2.

The Carbon Trading Price and Trading Volume Forecast in Shanghai City by BP Neural Network

OpenAIRE

Liu Zhiyuan; Sun Zongdi

2017-01-01

In this paper, the BP neural network model is established to predict the carbon trading price and carbon trading volume in Shanghai City. First of all, we find the data of carbon trading price and carbon trading volume in Shanghai City from September 30, 2015 to December 23, 2016. The carbon trading price and trading volume data were processed to get the average value of each 5, 10, 20, 30, and 60 carbon trading price and trading volume. Then, these data are used as input of BP neural network...

Sea urchin-like mesoporous carbon material grown with carbon nanotubes as a cathode catalyst support for fuel cells

Energy Technology Data Exchange (ETDEWEB)

Kuo, Ping-Lin; Hsu, Chun-Han; Li, Wan-Ting; Jhan, Jing-Yi; Chen, Wei-Fu [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101 (China)

2010-12-15

A sea urchin-like carbon (UC) material with high surface area (416 m{sup 2} g{sup -1}), adequate electrical conductivity (59.6 S cm{sup -1}) and good chemical stability was prepared by growing carbon nanotubes onto mesoporous carbon hollow spheres. A uniform dispersion of Pt nanoparticles was then anchored on the UC, where the Pt nanoparticles were prepared using benzylamine as the stabilizer. For this Pt loaded carbon, cyclic voltammogram measurements showed an exceptionally high electrochemically active surface area (EAS) (114.8 m{sup 2} g{sup -1}) compared to the commonly used commercial E-TEK catalyst (65.2 m{sup 2} g{sup -1}). The durability test demonstrates that the carbon used as a support exhibited minor loss in EAS of Pt. Compared to the E-TEK (20 wt%) cathode catalyst, this Pt loaded UC catalyst has greatly enhanced catalytic activity toward the oxygen reduction reaction, less cathode flooding and considerably improved performance, resulting in an enhancement of ca. 37% in power density compared with that of E-TEK. Based on the results obtained, the UC is an excellent support for Pt nanoparticles used as cathode catalysts in proton exchange membrane fuel cells. (author)

Atmospheric carbon injection linked to end-Triassic mass extinction.

Science.gov (United States)

Ruhl, Micha; Bonis, Nina R; Reichart, Gert-Jan; Sinninghe Damsté, Jaap S; Kürschner, Wolfram M

2011-07-22

The end-Triassic mass extinction (~201.4 million years ago), marked by terrestrial ecosystem turnover and up to ~50% loss in marine biodiversity, has been attributed to intensified volcanic activity during the break-up of Pangaea. Here, we present compound-specific carbon-isotope data of long-chain n-alkanes derived from waxes of land plants, showing a ~8.5 per mil negative excursion, coincident with the extinction interval. These data indicate strong carbon-13 depletion of the end-Triassic atmosphere, within only 10,000 to 20,000 years. The magnitude and rate of this carbon-cycle disruption can be explained by the injection of at least ~12 × 10(3) gigatons of isotopically depleted carbon as methane into the atmosphere. Concurrent vegetation changes reflect strong warming and an enhanced hydrological cycle. Hence, end-Triassic events are robustly linked to methane-derived massive carbon release and associated climate change.

The influence of cerium and yttrium ion implantation upon the oxidation behaviour of a 20% Cr/25% Ni/Nb stabilised stainless steel, in carbon dioxide, at 8250C

International Nuclear Information System (INIS)

Bennett, M.J.; Dearnaley, G.; Houlton, M.R.; Hawes, R.W.M.

1982-01-01

The influence of cerium and yttrium ion implantation upon the oxidation behaviour of a 20% Cr/25% Ni niobium stabilised stainless steel during up to 7 157h exposure to carbon dioxide, at 825 0 C has been examined. The doses ranged between 5 x 10 14 and 10 17 ions cm -2 . Above thresholds of between 5 x 10 14 and 5 x 10 15 yttrium and between 5 x 10 15 and 10 16 cerium ions cm -2 the implantation of both elements improved the oxidation resistance of the 20/25/Nb steel. Yttrium exerted the greater influence, reducing by a factor of two the attack after 7 157h. Up to 80% of the oxide formed on the 20/25/Nb steel spalled, particularly on thermal cycling. Cerium and yttrium implantation improved oxide adhesion by similar extents, which increased with ion dose such that with the highest doses, no spallation was measurable. The effect of the implanted elements derived from their incorporation within the oxide film. It was initiated by their promotion of the formation of an initial chromium-rich oxide layer, which had a finer grain size than that formed on the 20/25/Nb steel. Reduction in continuing attack was associated in part, with improved oxide adhesion, as this decreased the significant contribution to the attack of the 20/25/Nb steel from the reoxidation of spalled areas. (author)

Carbon-layer-protected cuprous oxide nanowire arrays for efficient water reduction

KAUST Repository

Zhang, Zhonghai

2013-02-26

In this work, we propose a solution-based carbon precursor coating and subsequent carbonization strategy to form a thin protective carbon layer on unstable semiconductor nanostructures as a solution to the commonly occurring photocorrosion problem of many semiconductors. A proof-of-concept is provided by using glucose as the carbon precursor to form a protective carbon coating onto cuprous oxide (Cu2O) nanowire arrays which were synthesized from copper mesh. The carbon-layer-protected Cu2O nanowire arrays exhibited remarkably improved photostability as well as considerably enhanced photocurrent density. The Cu2O nanowire arrays coated with a carbon layer of 20 nm thickness were found to give an optimal water splitting performance, producing a photocurrent density of -3.95 mA cm-2 and an optimal photocathode efficiency of 0.56% under illumination of AM 1.5G (100 mW cm-2). This is the highest value ever reported for a Cu 2O-based electrode coated with a metal/co-catalyst-free protective layer. The photostability, measured as the percentage of the photocurrent density at the end of 20 min measurement period relative to that at the beginning of the measurement, improved from 12.6% on the bare, nonprotected Cu2O nanowire arrays to 80.7% on the continuous carbon coating protected ones, more than a 6-fold increase. We believe that the facile strategy presented in this work is a general approach that can address the stability issue of many nonstable photoelectrodes and thus has the potential to make a meaningful contribution in the general field of energy conversion. © 2013 American Chemical Society.

TYPE Ia SUPERNOVA CARBON FOOTPRINTS

International Nuclear Information System (INIS)

Thomas, R. C.; Nugent, P.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Hsiao, E. Y.; Loken, S.; Antilogus, P.; Bongard, S.; Canto, A.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Paech, K.; Chotard, N.; Copin, Y.; Gangler, E.

2011-01-01

We present convincing evidence of unburned carbon at photospheric velocities in new observations of five Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 days relative to maximum. Detections are based on the presence of relatively strong C II λ6580 absorption 'notches' in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the five SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibit high-velocity (v > 20, 000 km s –1 ) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broadband light curve/color behavior: three of the five have relatively narrow light curves but also blue colors and a fourth may be a dust-reddened member of this family. Accounting for signal to noise and phase, we estimate that 22 +10 –6% of SNe Ia exhibit spectroscopic C II signatures as late as –5 days with respect to maximum. We place these new objects in the context of previously recognized carbon-positive SNe Ia and consider reasonable scenarios seeking to explain a physical connection between light curve properties and the presence of photospheric carbon. We also examine the detailed evolution of the detected carbon signatures and the surrounding wavelength regions to shed light on the distribution of carbon in the ejecta. Our ability to reconstruct the C II λ6580 feature in detail under the assumption of purely spherical symmetry casts doubt on a 'carbon blobs' hypothesis, but does not rule out all asymmetric models. A low volume filling factor for carbon, combined with line-of-sight effects, seems unlikely to explain the scarcity of detected carbon in SNe Ia by itself.

The influence of bubbles on the perception carbonation bite.

Directory of Open Access Journals (Sweden)

Paul M Wise

Full Text Available Although many people naively assume that the bite of carbonation is due to tactile stimulation of the oral cavity by bubbles, it has become increasingly clear that carbonation bite comes mainly from formation of carbonic acid in the oral mucosa. In Experiment 1, we asked whether bubbles were in fact required to perceive carbonation bite. Subjects rated oral pungency from several concentrations of carbonated water both at normal atmospheric pressure (at which bubbles could form and at 2.0 atmospheres pressure (at which bubbles did not form. Ratings of carbonation bite under the two pressure conditions were essentially identical, indicating that bubbles are not required for pungency. In Experiment 2, we created controlled streams of air bubbles around the tongue in mildly pungent CO2 solutions to determine how tactile stimulation from bubbles affects carbonation bite. Since innocuous sensations like light touch and cooling often suppress pain, we predicted that bubbles might reduce rated bite. Contrary to prediction, air bubbles flowing around the tongue significantly enhanced rated bite, without inducing perceived bite in blank (un-carbonated solutions. Accordingly, though bubbles are clearly not required for carbonation bite, they may well modulate perceived bite. More generally, the results show that innocuous tactile stimulation can enhance chemogenic pain. Possible physiological mechanisms are discussed.

A Data Base of Crop Nutrient Use, Water Use, and Carbon Dioxide Exchange in a 20 Square Meter Growth Chamber. Part 1; Wheat as a Case Study

Science.gov (United States)

Wheeler, Raymond M.; Berry, Wade L.; Mackowiak, Cheryl; Corey, Kenneth A.; Sager, John C.; Heeb, Margaret M.; Knott, William M.

1993-01-01

A data set is given describing the daily nutrient uptake, gas exchange, environmental conditions, and carbon (C), and nutrient partitioning at harvest for the entire canopy and root system of a wheat crop (Triticum aestivum, cv. Yecora Rojo). The data were obtained from a 20 sq m stand of wheat plants grown from planting to maturity in a closed, controlled environment, and include daily nutrient uptake [macronutrients, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S); and micronutrients, iron (Fe), boron (B), manganese (Mn), zinc (Zn), copper (Cu), and molybdenum (Mo)], canopy carbon dioxide (CO2) exchange rates, and transpiration. Environmental factors such as relative humidity, air temperature, nutrient solution temperature, pH and electrical conductivity, and photoperiod were controlled in the chamber to specific set points. A detailed description of biomass yield for each of the 64 plant growth trays comprising the 20 sq m of growth area is also provided, and includes dry weights of grain, straw, chaff, and roots, along with the concentration of nutrients in different plant tissues and the percent carbohydrate, fat, and protein. To our knowledge, this information represents one of the most extensive data sets available for a canopy of wheat grown from seed to maturity under controlled environmental and nutritional conditions, and thus may provide useful information for model development and validation. A methods section is included to qualify any assumptions that might he required for the use of the data in plant growth models, along with a daily event calendar indicating when adjustments in set points and occasional equipment or sensor failures occurred.

Evolution of Carbon Clusters in the Detonation Products of the Triaminotrinitrobenzene (TATB)-Based Explosive PBX 9502

Energy Technology Data Exchange (ETDEWEB)

Watkins, Erik B. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States; Velizhanin, Kirill A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States; Dattelbaum, Dana M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States; Gustavsen, Richard L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States; Aslam, Tariq D. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States; Podlesak, David W. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States; Huber, Rachel C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States; Firestone, Millicent A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States; Ringstrand, Bryan S. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States; Willey, Trevor M. [Lawrence Livermore National Laboratory, Livermore, California 94550, United States; Bagge-Hansen, Michael [Lawrence Livermore National Laboratory, Livermore, California 94550, United States; Hodgin, Ralph [Lawrence Livermore National Laboratory, Livermore, California 94550, United States; Lauderbach, Lisa [Lawrence Livermore National Laboratory, Livermore, California 94550, United States; van Buuren, Tony [Lawrence Livermore National Laboratory, Livermore, California 94550, United States; Sinclair, Nicholas [Washington State University, Pullman, Washington 99164, United States; Rigg, Paulo A. [Washington State University, Pullman, Washington 99164, United States; Seifert, Soenke [Argonne National Laboratory, Lemont, Illinois 60439, United States; Gog, Thomas [Argonne National Laboratory, Lemont, Illinois 60439, United States

2017-10-05

The detonation of carbon-rich high explosives yields solid carbon as a major constituent of the product mixture and, depending on the thermodynamic conditions behind the shock front, a variety of carbon allotropes and morphologies may form and evolve. We applied time-resolved small angle x-ray scattering (TR-SAXS) to investigate the dynamics of carbon clustering during detonation of PBX 9502, an explosive composed of triaminotrinitrobenzene (TATB) and 5 wt% fluoropolymer binder. Solid carbon formation was probed from 0.1 to 2.0 μs behind the detonation front and revealed rapid carbon cluster growth which reached a maximum after ~200 ns. The late-time carbon clusters had a radius of gyration of 3.3 nm which is consistent with 8.4 nm diameter spherical particles and matched particle sizes of recovered products. Simulations using a clustering kinetics model were found to be in good agreement with the experimental measurements of cluster growth when invoking a freeze-out temperature, and temporal shift associated with the initial precipitation of solid carbon. Product densities from reactive flow models were compared to the electron density contrast obtained from TR-SAXS and used to approximate the carbon cluster composition as a mixture of 20% highly ordered (diamond-like) and 80% disordered carbon forms, which will inform future product equation of state models for solid carbon in PBX 9502 detonation product mixtures.

Assessing ocean alkalinity for carbon sequestration

Science.gov (United States)

Renforth, Phil; Henderson, Gideon

2017-09-01

Over the coming century humanity may need to find reservoirs to store several trillions of tons of carbon dioxide (CO2) emitted from fossil fuel combustion, which would otherwise cause dangerous climate change if it were left in the atmosphere. Carbon storage in the ocean as bicarbonate ions (by increasing ocean alkalinity) has received very little attention. Yet recent work suggests sufficient capacity to sequester copious quantities of CO2. It may be possible to sequester hundreds of billions to trillions of tons of C without surpassing postindustrial average carbonate saturation states in the surface ocean. When globally distributed, the impact of elevated alkalinity is potentially small and may help ameliorate the effects of ocean acidification. However, the local impact around addition sites may be more acute but is specific to the mineral and technology. The alkalinity of the ocean increases naturally because of rock weathering in which >1.5 mol of carbon are removed from the atmosphere for every mole of magnesium or calcium dissolved from silicate minerals (e.g., wollastonite, olivine, and anorthite) and 0.5 mol for carbonate minerals (e.g., calcite and dolomite). These processes are responsible for naturally sequestering 0.5 billion tons of CO2 per year. Alkalinity is reduced in the ocean through carbonate mineral precipitation, which is almost exclusively formed from biological activity. Most of the previous work on the biological response to changes in carbonate chemistry have focused on acidifying conditions. More research is required to understand carbonate precipitation at elevated alkalinity to constrain the longevity of carbon storage. A range of technologies have been proposed to increase ocean alkalinity (accelerated weathering of limestone, enhanced weathering, electrochemical promoted weathering, and ocean liming), the cost of which may be comparable to alternative carbon sequestration proposals (e.g., $20-100 tCO2-1). There are still many

Transition between laser absorption dominated regimes in carbon-based plasma

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K. Hajisharifi

2017-09-01

Full Text Available In this work, we investigate the energy absorption enhancement of a laser by adding a variety of light ion species to a primarily carbon-based plasma during the high-power laser interaction with the finite size targets. A developed Particle-In-Cell simulation code is used to study the reduction of laser reflectivity (stimulated backward scatterings in both Brillouin- and Raman-dominated regimes. The simulation is performed in various Carbon-light ion plasmas such as Carbon-Hydrogen, Carbon-Helium, Carbon-Deuterium, and Carbon-Tritium. The results show that, in the optimized condition, the inclusion of light Hydrogen ions into the Carbon-based plasma up to 50%-50% mixture enhances the laser absorption exceeding 20% in the Brillouin regime due to the suppression of laser reflectivity in contract to 4% in the Raman-dominated regime. Moreover, the absorption dominated regime switches from Raman to Brillouin regime by adding 50% of Hydrogen ions to a purely carbon target. The results of this investigation will be applicable to the laser-plasma experiments so long as the laser energy absorption in the Carbon plasma target, the most readily available material in laboratory, is concerned.

Carbon electrode for desalination purpose in capacitive deionization

International Nuclear Information System (INIS)

Endarko,; Fadilah, Nurul; Anggoro, Diky

2016-01-01

Carbon electrodes for desalination purpose have been successfully synthesized using activated carbon powder (BET surface area=700 – 1400 m 2 /g), carbon black and polyvinyl alcohol (PVA) binder by cross-linking method with glutaric acid (GA) at 120 °C. The electrochemical properties of the carbon electrodes were analyzed using electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV) whilst the physical properties were observed with scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX). In order to assess the desalting performance, salt removal experiments were performed by constructing a capacitive deionization unit cell with five pairs of carbon electrodes. For each pair consisted of two parallel carbon electrodes separated by a spacer. Desalination and regeneration processes were also observed in the salt-removal experiments. The salt-removal experiments were carried out in single-pass mode using a solution with 0.1 M NaCl at a flow rate of 10 mL/min. A voltage of 3 V was applied to the cell for 60 minutes for both processes in desalination and regeneration. The result showed that the percentage value of the salt-removal was achieved at 20%.

Carbon electrode for desalination purpose in capacitive deionization

Energy Technology Data Exchange (ETDEWEB)

Endarko,, E-mail: endarko@physics.its.ac.id; Fadilah, Nurul; Anggoro, Diky [Physics Department, Institut Teknologi Sepuluh Nopember (ITS) Kampus ITS, Sukolilo Surabaya 60111, Jawa Timur (Indonesia)

2016-03-11

Carbon electrodes for desalination purpose have been successfully synthesized using activated carbon powder (BET surface area=700 – 1400 m{sup 2}/g), carbon black and polyvinyl alcohol (PVA) binder by cross-linking method with glutaric acid (GA) at 120 °C. The electrochemical properties of the carbon electrodes were analyzed using electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV) whilst the physical properties were observed with scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX). In order to assess the desalting performance, salt removal experiments were performed by constructing a capacitive deionization unit cell with five pairs of carbon electrodes. For each pair consisted of two parallel carbon electrodes separated by a spacer. Desalination and regeneration processes were also observed in the salt-removal experiments. The salt-removal experiments were carried out in single-pass mode using a solution with 0.1 M NaCl at a flow rate of 10 mL/min. A voltage of 3 V was applied to the cell for 60 minutes for both processes in desalination and regeneration. The result showed that the percentage value of the salt-removal was achieved at 20%.

Electroslag welding of rotor steels produced with vacuum-carbon reduction

International Nuclear Information System (INIS)

Roshchin, M.B.; Modzhuk, M.D.; Izvekov, B.V.

1985-01-01

Metallurgical processes of electroslag welding of rotor steels, melted with vacuum-carbon deoxidation, have been considered. It is established, that during electroslag welding of steels with carbon content 0.20...0.30%, suppression of welding bath boiling and production of dense weld metal with a high impact strength can be ensured at oxygen concentration in soldered on metal not exceeding 0.01% and silicon content 0.06...0.10%

Disinfection of bacteria attached to granular activated carbon.

Science.gov (United States)

LeChevallier, M W; Hassenauer, T S; Camper, A K; McFeters, G A

1984-01-01

Heterotrophic plate count bacteria, coliform organisms, and pathogenic microorganisms attached to granular activated carbon particles were examined for their susceptibility to chlorine disinfection. When these bacteria were grown on carbon particles and then disinfected with 2.0 mg of chlorine per liter (1.4 to 1.6 mg of free chlorine residual per liter after 1 h) for 1 h, no significant decrease in viable counts was observed. Washed cells attached to the surface of granular activated carbon particles showed similar resistance to chlorine, but a progressive increase in sublethal injury was found. Observations made by scanning electron microscope indicated that granular activated carbon was colonized by bacteria which grow in cracks and crevices and are coated by an extracellular slime layer. These data suggest a possible mechanism by which treatment and disinfection barriers can be penetrated and pathogenic bacteria may enter drinking water supplies. Images PMID:6508306

A unique research partnership investigating the fundamental principles of subsurface carbon dioxide behaviour and carbonate reservoirs

Science.gov (United States)

Macdonald, I.; Blunt, M. J.; Maitland, G. C.

2017-12-01

Carbonate reservoirs hold the majority of CO2 sequestration potential, however, they are also more complicated than sandstone reservoirs in terms of heterogeneity and potential reactivity impact on operations. There are both significant carbonate reservoir CO2 sinks and CO2 point sources around Qatar making carbon capture and storage a potential decarbonisation pathway. The Qatar Carbonates and Carbon Storage Research Centre (QCCSRC) was formed in 2009 to address the gaps in our current knowledge of both local carbonate reservoir platforms and how CO2 would behave post sequestration. Our work spans 35 graduated PhD students, 10 still studying, 29 post-doctoral researchers, 18 faculty members all aided by 5 support staff and more than 100 MSc and summer students from 30 different countries, the centre has published over 150 papers in over 40 different journals. Our research is based within the Department of Chemical Engineering and the Department of Earth Science and Engineering. Our team annually attends over 20 conferences world-wide to disseminate our findings and activity engage in outreach events (UNFCCC, science festivals, social media, science bars, school visits, etc.). QCCSRC is a research framework agreement over 10 years and valued at $70 million between Qatar Petroleum, Shell, the Qatar Science and Technology Park and Imperial College London bringing together each organisation's unique capabilities. This novel quadruple helix management structure is responsible for the largest single industrially funded research programme conducted at Imperial College London. Our research has focused on data to create and/or improve predictive models for CO2 storage in carbonate reservoirs. Our three broad thematic areas include: Rocks : Rock-fluid interactions : Fluid-fluid interactions and are supported by 5 laboratories. Overall this unique programme is an example of how to approach grand challenges in the energy-carbon dilemma through long-term and multidisciplinary

Natural gas storage with activated carbon from a bituminous coal

Science.gov (United States)

Sun, Jielun; Rood, M.J.; Rostam-Abadi, M.; Lizzio, A.A.

1996-01-01

Granular activated carbons ( -20 + 100 mesh; 0.149-0.84 mm) were produced by physical activation and chemical activation with KOH from an Illinois bituminous coal (IBC-106) for natural gas storage. The products were characterized by BET surface area, micropore volume, bulk density, and methane adsorption capacities. Volumetric methane adsorption capacities (Vm/Vs) of some of the granular carbons produced by physical activation are about 70 cm3/cm3 which is comparable to that of BPL, a commercial activated carbon. Vm/Vs values above 100 cm3/cm3 are obtainable by grinding the granular products to - 325 mesh (activated carbons, granular carbons produced by KOH activation have higher micropore volume and higher methane adsorption capacities (g/g). Their volumetric methane adsorption capacities are lower due to their lower bulk densities. Copyright ?? 1996 Elsevier Science Ltd.

The EU 20/20/2020 targets. An overview of the EMF22 assessment

Energy Technology Data Exchange (ETDEWEB)

Boehringer, Christoph [Department of Economics, Carl on Ossietzky University, Oldenburg (Germany); Rutherford, Thomas F. [Centre for Energy Policy and Economics, ETH, Zurich (Switzerland); Tol, Richard S.J. [Economic and Social Research Institute, Dublin (Ireland); Institute for Environmental Studies, Vrije Universiteit, Amsterdam (Netherlands); Department of Spatial Economics, Vrije Universiteit, Amsterdam (Netherlands)

2009-07-01

Three computable general equilibrium models are used to estimate the economic implications of a stylized version of EU climate policy. If implemented at the lowest possible cost, the 20% emissions reduction would lead to a welfare loss of 0.5-2.0% by 2020. Second-best policies increase costs. A policy with two carbon prices (one for the ETS, one for the non-ETS) could increase costs by up to 50%. A policy with 28 carbon prices (one for the ETS, one each for each Member State) could increase costs by another 40%. The renewables standard could raise the costs of emissions reduction by 90%. Overall, the inefficiencies in policy lead to a cost that is 100-125% too high. The models differ greatly in the detail of their results. The ETS/non-ETS split may have a negligible impact on welfare, while the renewables standard may even improve welfare. The models agree, however, that the distortions introduced by total EU package imply a substantial welfare loss over and above the costs needed to meet the climate target. The marginal, total and excess costs reported here are notably higher than those in the impact assessment of the European Commission. (author)

SOIL ORGANIC CARBON LEVELS IN SOILS OF CONTRASTING LAND USES IN SOUTHEASTERN NIGERIA

Directory of Open Access Journals (Sweden)

Chinyere Blessing Okebalama

2017-12-01

Full Text Available Land use change affects soil organic carbon (SOC storage in tropical soils, but information on the influence of land use change on segmental topsoil organic carbon stock is lacking. The study investigated SOC levels in Awgu (L, Okigwe (CL, Nsukka I (SL, and Nsukka II (SCL locations in southeastern Nigeria. Land uses considered in each location were the cultivated (manually-tilled and the adjacent uncultivated (4-5 year bush-fallow soils from which samples at 0-10, 10-20, and 20-30 cm topsoil depth were assessed. The SOC level decreased with topsoil depth in both land uses. Overall, the SOC level at 0-30 cm was between 285.44 and 805.05 Mg ha-1 amongst the soils.  The uncultivated sites stored more SOC than its adjacent cultivated counterpart at 0-10 and 10-20 cm depth, except in Nsukka II soils, which had significantly higher SOC levels in the cultivated than the uncultivated site. Nonetheless, at 20-30 cm depth, the SOC pool across the fallowed soils was statistically similar when parts of the same soil utilization type were tilled and cultivated. Therefore, while 4 to 5 years fallow may be a useful strategy for SOC stabilization within 20-30 cm topsoil depth in the geographical domain, segmental computation of topsoil organic carbon pool is critical.

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

Energy Technology Data Exchange (ETDEWEB)

Ghafari, Shahin; Hasan, Masitah [Department of Chemical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Aroua, Mohamed Kheireddine [Department of Chemical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)], E-mail: mk_aroua@um.edu.my

2009-03-15

Acclimation of autohydrogenotrophic denitrifying bacteria using inorganic carbon source (CO{sub 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{sub 2}, (II) bicarbonate plus continuous sparging of CO{sub 2}, and (III) only bicarbonate. The pH-reducing nature of CO{sub 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{sub 3}{sup -}-N/g MLVSS/h for degrading 20 and 30 mg NO{sub 3}{sup -}-N/L and 9.09 mg NO{sub 3}{sup -}-N/g MLVSS/h for degrading 50 mg NO{sub 3}{sup -}-N/L.

Preliminary Study of Fermented Tapioca for Synthesis of Carbon Nano tubes

International Nuclear Information System (INIS)

Nurulhuda Ismail; Ying, P.Y.

2011-01-01

Carbon nano tubes had been produced by various precursor such as gas (methane, carbon dioxide), oil (camphor oil, olive oil, and cooking oil) and alcohol. Different methods used for carbon nano tubes synthesis like arc discharge method, laser ablation method and chemical vapour deposition method. In this experiment, thermal chemical vapour deposition method was selected for carbon nano tubes synthesis. Starting material of fermented tapioca was used as carbon source for the process. Argon gas flow were controlled at around 10-15 bubbles per minute and deposition time around 20 to 30 minute. Others parameters such as temperature of furnace 1 and 2, amount of inoculum and catalyst have been studied. The asThermogravimetri (TGA) was used to determine the volatile temperature of the mixing catalyst and fermented tapioca extract. The grown carbon nano tubes morphology was characterized through Raman spectroscopy, scanning and Field Emission Scanning Electron Microscopy (FESEM) techniques. The surface morphology and uniformity of carbon nano tubes are reliant to parameters used. (author)

Empirical High-Temperature Calibration for the Carbonate Clumped Isotopes Paleothermometer

Science.gov (United States)

Kluge, T.; John, C. M.; Jourdan, A.; Davis, S.; Crawshaw, J.

2013-12-01

The clumped isotope paleothermometer is being used in a wide range of applications related to carbonate mineral formation, focusing on temperature and fluid δ18O reconstruction. Whereas the range of typical Earth surface temperatures has been the focus of several studies based on laboratory experiments and biogenic carbonates of known growth temperatures, the clumped isotope-temperature relationship above 70 °C has not been assessed by direct precipitation of carbonates. We investigated the clumped isotope-temperature relationship by precipitating carbonates between 20 and 200°C in the laboratory. The setup consists of a pressurized vessel in which carbonate minerals are precipitated from the mixture of two solutions (CaCl2, NaHCO3). Both solutions are thermally and isotopically equilibrated before injection in the pressure vessel. Minerals precipitated in this setup generally consist of calcite. Samples were reacted with 105% orthophosphoric acid for 10 min at 90°C. The evolved CO2 was continuously collected and subsequently purified with a Porapak trap held at -35°C. Measurements were performed on a MAT 253 using the protocol of Huntington et al. (2009) and Dennis et al. (2011). Clumped isotope values from 20-90°C are consistent with carbonates that were precipitated from a CaCO3 super-saturated solution using the method of McCrea (1950). This demonstrates that the experimental setup does not induce any kinetic fractionation, and can be used for high-temperature carbonate precipitation. The new clumped isotope calibration at high temperature follows the theoretical calculations of Schauble et al. (2006) adjusted for phosphoric acid digestion at 90°C. We gratefully acknowledge funding from Qatar Petroleum, Shell and the Qatar Science and Technology Park.

Evaluation of Production and Carbon Benefit of Different Vegetables

Directory of Open Access Journals (Sweden)

HU Liang

2016-01-01

Full Text Available This study analyzed environmental and economic benefits of 8 types of vegetables in 4 different farms over 3 years. The specific results were as follows:(1The input-output ratio and carbon footprint of organic production mode was 18.5% and 87.4% of that of pollution-free mode, respectively; (2Fertilizer and power consumption was the main source of carbon emissions, accounting for 58.76% and 16.67% of total carbon emissions, respectively; (3There were positive correlations between N fertilizer and both carbon emissions and carbon footprint. In other words, higher use of N fertilizer resulted in higher carbon emissions and carbon footprint; (4 When organic fertilizers use reached 122 352 kg·hm-2, the crop production could reach the maximum under organic mode. Under the mode of pollution-free production, when agricultural chemicals input reached 20 103 yuan·hm-2, leafy vegetable production could reach the maximum. Therefore, to increase production and reduce carbon emissions in the process of vegetable production, the main approach was to use organic mode, increase the quantity of organic fertilizer, instead of the use of inorganic N fertilizer and other agricultural chemicals and establish water-saving irrigation system for electricity efficiency.

Observed 20th century desert dust variability: impact on climate and biogeochemistry

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N. M. Mahowald

2010-11-01

Full Text Available Desert dust perturbs climate by directly and indirectly interacting with incoming solar and outgoing long wave radiation, thereby changing precipitation and temperature, in addition to modifying ocean and land biogeochemistry. While we know that desert dust is sensitive to perturbations in climate and human land use, previous studies have been unable to determine whether humans were increasing or decreasing desert dust in the global average. Here we present observational estimates of desert dust based on paleodata proxies showing a doubling of desert dust during the 20th century over much, but not all the globe. Large uncertainties remain in estimates of desert dust variability over 20th century due to limited data. Using these observational estimates of desert dust change in combination with ocean, atmosphere and land models, we calculate the net radiative effect of these observed changes (top of atmosphere over the 20th century to be −0.14 ± 0.11 W/m² (1990–1999 vs. 1905–1914. The estimated radiative change due to dust is especially strong between the heavily loaded 1980–1989 and the less heavily loaded 1955–1964 time periods (−0.57 ± 0.46 W/m², which model simulations suggest may have reduced the rate of temperature increase between these time periods by 0.11 °C. Model simulations also indicate strong regional shifts in precipitation and temperature from desert dust changes, causing 6 ppm (12 PgC reduction in model carbon uptake by the terrestrial biosphere over the 20th century. Desert dust carries iron, an important micronutrient for ocean biogeochemistry that can modulate ocean carbon storage; here we show that dust deposition trends increase ocean productivity by an estimated 6% over the 20th century, drawing down an additional 4 ppm (8 PgC of carbon dioxide into the oceans. Thus, perturbations to desert dust over the 20th century inferred from observations are potentially important for climate and

Above Ground Biomass-carbon Partitioning, Storage and Sequestration in a Rehabilitated Forest, Bintulu, Sarawak, Malaysia

International Nuclear Information System (INIS)

Kueh, J.H.R.; Majid, N.M.A.; Seca, G.; Ahmed, O.H.

2013-01-01

Forest degradation and deforestation are some of the major global concerns as it can reduce forest carbon storage and sequestration capacity. Forest rehabilitation on degraded forest areas has the potential to improve carbon stock, hence mitigate greenhouse gases emission. However, the carbon storage and sequestration potential in a rehabilitated tropical forest remains unclear due to the lack of information. This paper reports an initiative to estimate biomass-carbon partitioning, storage and sequestration in a rehabilitated forest. The study site was at the UPM-Mitsubishi Corporation Forest Rehabilitation Project, UPM Bintulu Sarawak Campus, Bintulu, Sarawak. A plot of 20 x 20 m 2 was established each in site 1991 (Plot 1991), 1999 (Plot 1999) and 2008 (Plot 2008). An adjacent natural regenerating secondary forest plot (Plot NF) was also established for comparison purposes. The results showed that the contribution of tree component biomass/ carbon to total biomass/ carbon was in the order of main stem > branch > leaf. As most of the trees were concentrated in diameter size class = 10 cm for younger rehabilitated forests, the total above ground biomass/ carbon was from this class. These observations suggest that the forests are in the early successional stage. The total above ground biomass obtained for the rehabilitated forest ranged from 4.3 to 4,192.3 kg compared to natural regenerating secondary forest of 3,942.3 kg while total above ground carbon ranged from 1.9 to 1,927.9 kg and 1,820.4 kg, respectively. The mean total above ground biomass accumulated ranged from 1.3 x 10 -2 to 20.5 kg/ 0.04 ha and mean total carbon storage ranged from 5.9 x 10 -3 to 9.4 kg/ 0.04 ha. The total CO 2 sequestrated in rehabilitated forest ranged from 6.9 to 7,069.1 kg CO 2 / 0.04 ha. After 19 years, the rehabilitated forest had total above ground biomass and carbon storage comparable to the natural regeneration secondary forest. The forest rehabilitated activities have the

Carbon allocation belowground in Pinus pinaster using stable carbon isotope pulse labeling technique

Science.gov (United States)

Dannoura, M.; Bosc, A.; Chipeaux, C.; Sartore, M.; Lambrot, C.; Trichet, P.; Bakker, M.; Loustau, D.; Epron, D.

2010-12-01

Carbon allocation belowground competes with aboveground growth and biomass production. In the other hand, it contributes to resource acquisition such as nutrient, water and carbon sequestration in soil. Thus, a better characterization of carbon flow from plant to soil and its residence time within each compartment is an important issue for understanding and modeling forest ecosystem carbon budget. 13C pulse labeling of whole crown was conducted at 4 seasons to study the fate of assimilated carbon by photosynthesis into the root on 12 year old Pinus pinaster planted in the INRA domain of Pierroton. Maritime pine is the most widely planted species in South-West Europe. Stem, root and soil CO2 effluxes and their isotope composition were measured continuously by tunable diode laser absorption spectroscopy with a trace gas analyzer (TGA 100A; Campbell Scientific) coupled to flow-through chambers. 13CO2 recovery and peak were observed in respiration of each compartment after labeling. It appeared sequentially from top of stem to bottom, and to coarse root. The maximum velocity of carbon transfer was calculated as the difference in time lag of recovery between two positions on the trunk or on the root. It ranged between 0.08-0.2 m h-1 in stem and between 0.04-0.12 m h-1 in coarse root. This velocity was higher in warmer season, and the difference between time lag of recovery and peak increased after first frost. Photosynthates arrived underground 1.5 to 5 days after labeling, at similar time in soil CO2 effluxes and coarse root respiration. 0.08-1.4 g of carbon was respired per tree during first 20 days following labeling. It presented 0.6 -10% of 13C used for labeling and it is strongly related to seasons. The isotope signal was detected in fine root organs and microbial biomass by periodical core sampling. The peak was observed 6 days after labeling in early summer while it was delayed more than 10 days in autumn and winter with less amount of carbon allocated

Electrochemical pre anodization of glassy carbon electrode and application to determine chloramphenicol

International Nuclear Information System (INIS)

Truc, Nguyen Minh; Mortensen, John; Anh, Nguyen Ba Hoai

2008-01-01

This paper suggested a method to enhance the performance of carbon electrodes for the determination of chloramphenicol (CAP). The sensitivity and the reproducibility of the carbon electrodes could be enhanced easily by electrochemical pretreatment. Some kinds of carbon material were studied including glassy carbon, graphite carbon and pyrolytic carbon. Numerous kinds of supporting electrolyte have been tried. For glassy carbon electrode, the acidic solution, H 2 SO 4 5 mM, resulted in best performance at pretreated voltage of +2.1V (vs. Ag/ AgCl) in duration of 250 second. However, for graphite and pyrolytic carbon electrodes, the phosphate buffer solution pH 6.0 gave the best performance at +1.7V (vs. Ag/ AgCl) in duration of 20 seconds. The detection limit could be at very low concentration of CAP: 0.8 ng/ ml for glassy carbon electrode, 3.5 ng/ ml for graphite carbon electrode. The method was successful applied to aqua-agriculture water sample and milk sample with simple extraction as well as direct ointment sample analysis. (author)

Experience with carbon ion radiotherapy at GSI

Energy Technology Data Exchange (ETDEWEB)

Jaekel, O. [Division of Medical Physics in Radiation Therapy (E040), German Cancer Research Center, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)]. E-mail: o.jaekel@dkfz.de; Schulz-Ertner, D. [Department of Radiation Oncology, University of Heidelberg, Heidelberg (Germany); Karger, C.P. [Division of Medical Physics in Radiation Therapy (E040), German Cancer Research Center, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Heeg, P. [Division of Medical Physics in Radiation Therapy (E040), German Cancer Research Center, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Debus, J. [Department of Radiation Oncology, University of Heidelberg, Heidelberg (Germany)

2005-12-15

At GSI, a radiotherapy facility was established using beam scanning and active energy variation. Between December 1997 and April 2004, 220 patients have been treated at this facility with carbon ions. Most patients are treated for chordoma and chondrosarcoma of the base of skull, using a dose of 60 Gye (Gray equivalent) in 20 fractions. Carbon ion therapy is also offered in a combination with conventional radiotherapy for a number of other tumors (adenoidcystic carcinoma, chordoma of the cervical spine and sacrum, atypical menningeoma). The patients treated for skull base tumors showed an overall local control rate after two years of 90%. The overall treatment toxicity was mild. This shows that carbon ion radiotherapy can safely be applied using a scanned beam and encouraged the Heidelberg university hospital to build a hospital based facility for ion therapy.

Estimating the carbon budget and maximizing future carbon uptake for a temperate forest region in the U.S.

Science.gov (United States)

2012-01-01

Background Forests of the Midwest U.S. provide numerous ecosystem services. Two of these, carbon sequestration and wood production, are often portrayed as conflicting. Currently, carbon management and biofuel policies are being developed to reduce atmospheric CO2 and national dependence on foreign oil, and increase carbon storage in ecosystems. However, the biological and industrial forest carbon cycles are rarely studied in a whole-system structure. The forest system carbon balance is the difference between the biological (net ecosystem production) and industrial (net emissions from forest industry) forest carbon cycles, but to date this critical whole system analysis is lacking. This study presents a model of the forest system, uses it to compute the carbon balance, and outlines a methodology to maximize future carbon uptake in a managed forest region. Results We used a coupled forest ecosystem process and forest products life cycle inventory model for a regional temperate forest in the Midwestern U.S., and found the net system carbon balance for this 615,000 ha forest was positive (2.29 t C ha-1 yr-1). The industrial carbon budget was typically less than 10% of the biological system annually, and averaged averaged 0.082 t C ha-1 yr-1. Net C uptake over the next 100-years increased by 22% or 0.33 t C ha-1 yr-1 relative to the current harvest rate in the study region under the optized harvest regime. Conclusions The forest’s biological ecosystem current and future carbon uptake capacity is largely determined by forest harvest practices that occurred over a century ago, but we show an optimized harvesting strategy would increase future carbon sequestration, or wood production, by 20-30%, reduce long transportation chain emissions, and maintain many desirable stand structural attributes that are correlated to biodiversity. Our results for this forest region suggest that increasing harvest over the next 100 years increases the strength of

Estimating the carbon budget and maximizing future carbon uptake for a temperate forest region in the U.S.

Directory of Open Access Journals (Sweden)

Peckham Scott D

2012-06-01

Full Text Available Abstract Background Forests of the Midwest U.S. provide numerous ecosystem services. Two of these, carbon sequestration and wood production, are often portrayed as conflicting. Currently, carbon management and biofuel policies are being developed to reduce atmospheric CO2 and national dependence on foreign oil, and increase carbon storage in ecosystems. However, the biological and industrial forest carbon cycles are rarely studied in a whole-system structure. The forest system carbon balance is the difference between the biological (net ecosystem production and industrial (net emissions from forest industry forest carbon cycles, but to date this critical whole system analysis is lacking. This study presents a model of the forest system, uses it to compute the carbon balance, and outlines a methodology to maximize future carbon uptake in a managed forest region. Results We used a coupled forest ecosystem process and forest products life cycle inventory model for a regional temperate forest in the Midwestern U.S., and found the net system carbon balance for this 615,000 ha forest was positive (2.29 t C ha-1 yr-1. The industrial carbon budget was typically less than 10% of the biological system annually, and averaged averaged 0.082 t C ha-1 yr-1. Net C uptake over the next 100-years increased by 22% or 0.33 t C ha-1 yr-1 relative to the current harvest rate in the study region under the optized harvest regime. Conclusions The forest’s biological ecosystem current and future carbon uptake capacity is largely determined by forest harvest practices that occurred over a century ago, but we show an optimized harvesting strategy would increase future carbon sequestration, or wood production, by 20-30%, reduce long transportation chain emissions, and maintain many desirable stand structural attributes that are correlated to biodiversity. Our results for this forest region suggest that increasing harvest over the next 100�

Structure and properties of carbon black particles

Science.gov (United States)

Xu, Wei

Structure and properties of carbon black particles were investigated using atomic force microscopy, gas adsorption, Raman spectroscopy, and X-ray diffraction. Supplementary information was obtained using TEM and neutron scattering. The AFM imaging of carbon black aggregates provided qualitative visual information on their morphology, complementary to that obtained by 3-D modeling based on TEM images. Our studies showed that carbon black aggregates were relatively flat. The surface of all untreated carbon black particles was found to be rough and its fractal dimension was 2.2. Heating reduced the roughness and fractal dimension for all samples heat treated at above 1300 K to 2.0. Once the samples were heat treated rapid cooling did not affect the surface roughness. However, rapid cooling reduced crystallite sizes, and different Raman spectra were obtained for carbon blacks of various history of heat treatment. By analyzing the Raman spectra we determined the crystallite sizes and identified amorphous carbon. The concentration of amorphous carbon depends on hydrogen content. Once hydrogen was liberated at increased temperature, the concentration of amorphous carbon was reduced and crystallites started to grow. Properties of carbon blacks at high pressure were also studied. Hydrostatic pressure did not affect the size of the crystallites in carbon black particles. The pressure induced shift in Raman frequency of the graphitic component was a result of increased intermolecular forces and not smaller crystallites. Two methods of determining the fractal dimension, the FHH model and the yardstick technique based on the BET theory were used in the literature. Our study proved that the FHH model is sensitive to numerous assumptions and leads to wrong conclusions. On the other hand the yardstick method gave correct results, which agreed with the AFM results.

Biological control of the terrestrial carbon sink

Science.gov (United States)

Schulze, E.-D.

2006-03-01

This lecture reviews the past (since 1964 when the International Biological Program began) and the future of our understanding of terrestrial carbon fluxes with focus on photosynthesis, respiration, primary-, ecosystem-, and biome-productivity. Photosynthetic capacity is related to the nitrogen concentration of leaves, but the capacity is only rarely reached under field conditions. Average rates of photosynthesis and stomatal conductance are closely correlated and operate near 50% of their maximal rate, with light being the limiting factor in humid regions and air humidity and soil water the limiting factor in arid climates. Leaf area is the main factor to extrapolate from leaves to canopies, with maximum surface conductance being dependent on leaf level stomatal conductance. Additionally, gas exchange depends also on rooting depth which determines the water and nutrient availability and on mycorrhizae which regulate the nutrient status. An important anthropogenic disturbance is the nitrogen uptake from air pollutants, which is not balanced by cation uptake from roots and this may lead to damage and breakdown of the plant cover. Photosynthesis is the main carbon input into ecosystems, but it alone does not represent the ecosystem carbon balance, which is determined by respiration of various kinds. Plant respiration and photosynthesis determine growth (net primary production) and microbial respiration balances the net ecosystem flux. In a spruce forest, 30% of the assimilatory carbon gain is used for respiration of needles, 20% is used for respiration in stems. Soil respiration is about 50% the carbon gain, half of which is root respiration, half is microbial respiration. In addition, disturbances lead to carbon losses, where fire, harvest and grazing bypass the chain of respiration. In total, the carbon balance at the biome level is only about 1% of the photosynthetic carbon input, or may indeed become negative. The recent observed increase in plant growth has

Biological control of the terrestrial carbon sink

Directory of Open Access Journals (Sweden)

E.-D. Schulze

2006-01-01

Full Text Available This lecture reviews the past (since 1964 when the International Biological Program began and the future of our understanding of terrestrial carbon fluxes with focus on photosynthesis, respiration, primary-, ecosystem-, and biome-productivity. Photosynthetic capacity is related to the nitrogen concentration of leaves, but the capacity is only rarely reached under field conditions. Average rates of photosynthesis and stomatal conductance are closely correlated and operate near 50% of their maximal rate, with light being the limiting factor in humid regions and air humidity and soil water the limiting factor in arid climates. Leaf area is the main factor to extrapolate from leaves to canopies, with maximum surface conductance being dependent on leaf level stomatal conductance. Additionally, gas exchange depends also on rooting depth which determines the water and nutrient availability and on mycorrhizae which regulate the nutrient status. An important anthropogenic disturbance is the nitrogen uptake from air pollutants, which is not balanced by cation uptake from roots and this may lead to damage and breakdown of the plant cover. Photosynthesis is the main carbon input into ecosystems, but it alone does not represent the ecosystem carbon balance, which is determined by respiration of various kinds. Plant respiration and photosynthesis determine growth (net primary production and microbial respiration balances the net ecosystem flux. In a spruce forest, 30% of the assimilatory carbon gain is used for respiration of needles, 20% is used for respiration in stems. Soil respiration is about 50% the carbon gain, half of which is root respiration, half is microbial respiration. In addition, disturbances lead to carbon losses, where fire, harvest and grazing bypass the chain of respiration. In total, the carbon balance at the biome level is only about 1% of the photosynthetic carbon input, or may indeed become negative. The recent observed increase in

Earthquake nucleation in weak subducted carbonates

Science.gov (United States)

Kurzawski, Robert M.; Stipp, Michael; Niemeijer, André R.; Spiers, Christopher J.; Behrmann, Jan H.

2016-09-01

Ocean-floor carbonate- and clay-rich sediments form major inputs to subduction zones, especially at low-latitude convergent plate margins. Therefore, knowledge of their frictional behaviour is fundamental for understanding plate-boundary earthquakes. Here we report results of mechanical tests performed on simulated fault gouges prepared from ocean-floor carbonates and clays, cored during IODP drilling offshore Costa Rica. Clay-rich gouges show internal friction coefficients (that is, the slope of linearized shear stress versus normal stress data) of μint = 0.44 - 0.56, irrespective of temperature and pore-fluid pressure (Pf). By contrast, μint for the carbonate gouge strongly depends on temperature and pore-fluid pressure, with μint decreasing dramatically from 0.84 at room temperature and Pf = 20 MPa to 0.27 at T = 140 °C and Pf = 120 MPa. This effect provides a fundamental mechanism of shear localization and earthquake generation in subduction zones, and makes carbonates likely nucleation sites for plate-boundary earthquakes. Our results imply that rupture nucleation is prompted by a combination of temperature-controlled frictional instability and temperature- and pore-pressure-dependent weakening of calcareous fault gouges.

Low temperature stabilization process for production of carbon fiber having structural order

Science.gov (United States)

Rios, Orlando; McGuire, Michael Alan; More, Karren Leslie; Tenhaeff, Wyatt Evan; Menchhofer, Paul A.; Paulauskas, Felix Leonard

2017-08-15

A method for producing a carbon fiber, the method comprising: (i) subjecting a continuous carbon fiber precursor having a polymeric matrix in which strength-enhancing particles are incorporated to a stabilization process during which the carbon fiber precursor is heated to within a temperature range ranging from the glass transition temperature to no less than 20.degree. C. below the glass transition temperature of the polymeric matrix, wherein the maximum temperature employed in the stabilization process is below 400.degree. C., for a processing time within said temperature range of at least 1 hour in the presence of oxygen and in the presence of a magnetic field of at least 1 Tesla, while said carbon fiber precursor is held under an applied axial tension; and (ii) subjecting the stabilized carbon fiber precursor, following step (i), to a carbonization process. The stabilized carbon fiber precursor, resulting carbon fiber, and articles made thereof are also described.

Ultrapulse carbon dioxide laser ablation of xanthelasma palpebrarum: A case series

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Vikas Pathania

2015-01-01

Full Text Available Context: Xanthelasma palpebrarum is the most common form of xanthomas. Albeit a benign entity, it is cosmetically disturbing and a frequently recurring dermatologic referral. Although the classical treatment option remains surgical excision, alternatively, chemical cauterization, cryosurgery and electrofulguration have all been tried in the past with mixed results. The use of laser systems such as carbon dioxide laser, Erb:YAG laser, Q-switched Nd:YAG laser, diode laser, pulsed dye laser and KTP laser have become popular in the treatment of these lesions. Recent literature suggests minimal pigmentary changes and scarring with the use of ultrapulse carbon dioxide laser treatment of these lesions. Aim: To study and evaluate the effectiveness of ultrapulse carbon dioxide laser ablation for treatment of xanthelasma palpebrarum. Materials and Methods: 10 patients presenting with bilateral xanthelasma palpebrarum, new and with recurrence were studied for results after a single treatment with ultrapulse carbon dioxide laser (10,600 nm; 100-200 Hz; 200-400 μsec. The follow-up time was 9 months. Results: All lesions were treatable with a single-laser treatment session. Two patients (20% developed recurrence during the follow-up period. Side effects included post inflammatory hyperpigmentation in two patients (20%, but no visible scarring was observed. Conclusions: The ultrapulse carbon dioxide laser is an effective and safe therapeutic alternative in treatment of xanthelasma palpebrarum.

Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation

Science.gov (United States)

Ziegler, Kirk J. (Inventor); Rauwald, Urs (Inventor); Hauge, Robert H. (Inventor); Schmidt, Howard K. (Inventor); Smalley, Richard E. (Inventor); Kittrell, W. Carter (Inventor); Gu, Zhenning (Inventor)

2013-01-01

According to some embodiments, the present invention provides a method for attaining short carbon nanotubes utilizing electron beam irradiation, for example, of a carbon nanotube sample. The sample may be pretreated, for example by oxonation. The pretreatment may introduce defects to the sidewalls of the nanotubes. The method is shown to produces nanotubes with a distribution of lengths, with the majority of lengths shorter than 100 tun. Further, the median length of the nanotubes is between about 20 nm and about 100 nm.

Carbon-On-Carbon Manufacturing

Science.gov (United States)

Mungas, Gregory S. (Inventor); Buchanan, Larry (Inventor); Banzon, Jr., Jose T. (Inventor)

2017-01-01

The presently disclosed technology relates to carbon-on-carbon (C/C) manufacturing techniques and the resulting C/C products. One aspect of the manufacturing techniques disclosed herein utilizes two distinct curing operations that occur at different times and/or using different temperatures. The resulting C/C products are substantially non-porous, even though the curing operation(s) substantially gasify a liquid carbon-entrained filler material that saturates a carbon fabric that makes up the C/C products.

Synthesis of Large Arrays of Well-Aligned Carbon Nanotubes on Glass

Energy Technology Data Exchange (ETDEWEB)

Bush, P. Siegal, M.P.; Huang, Z.P.; Provencio, P.N.; Ren, Z.F.; Wang, J.H.; Xu, J.W.

1998-11-10

Free-standing aligned carbon nanotubes have previously been grown above 7000C on mesoporous silica embedded with iron nanoparticles. Here, carbon nanotubes aligned over areas up to several square centimeters were grown on nickel-coated glass below 666oC by plasma-enhanced hot filament chemical vapor deposition. Acetylene (C2H2) gas was used as the carbon source and ammonia (NH3) gas was used as a catalyst and dilution gas. Nanotubes with controllable diameters from 20 to 400 nanometers and lengths from 0.1 to 50 micrometers were obtained. Using this method, large panels of aligned carbon nanotubes can be made under conditions that are suitable for device fabrication.

Emissions Inventory Report Summary: Reporting Requirements for the New Mexico Administrative code, Title 20, Chapter 2, Part 73 (20 NMAC 2.73) for Calendar Year 1997

International Nuclear Information System (INIS)

1999-01-01

Los Alamos National Laboratory (the Laboratory) is subject to emissions reporting requirements for regulated air contaminants under Title 20 of the New Mexico Administrative Code, Chapter 2, Part 73, (20 NMAC 2.73), Notice of Intent and Emissions Inventory Requirements. The Laboratory has the potential to emit 100 tons per year of suspended particulate matter (PM), nitrogen oxides (NO x ), carbon monoxide (CO), and volatile organic compounds (VOCs). For 1997, combustion products from the industrial sources contributed the greatest amount of regulated air emissions from the Laboratory. Research and development activities contributed the greatest amount of VOCs. Emissions of beryllium and aluminum were reported for activities permitted under 20 NMAC 2.72, Construction Permits

Dynamical and biogeochemical control on the decadal variability of ocean carbon fluxes

Directory of Open Access Journals (Sweden)

R. Séférian

2013-04-01

Full Text Available Several recent observation-based studies suggest that ocean anthropogenic carbon uptake has slowed down due to the impact of anthropogenic forced climate change. However, it remains unclear whether detected changes over the recent time period can be attributed to anthropogenic climate change or rather to natural climate variability (internal plus naturally forced variability alone. One large uncertainty arises from the lack of knowledge on ocean carbon flux natural variability at the decadal time scales. To gain more insights into decadal time scales, we have examined the internal variability of ocean carbon fluxes in a 1000 yr long preindustrial simulation performed with the Earth System Model IPSL-CM5A-LR. Our analysis shows that ocean carbon fluxes exhibit low-frequency oscillations that emerge from their year-to-year variability in the North Atlantic, the North Pacific, and the Southern Ocean. In our model, a 20 yr mode of variability in the North Atlantic air-sea carbon flux is driven by sea surface temperature variability and accounts for ~40% of the interannual regional variance. The North Pacific and the Southern Ocean carbon fluxes are also characterised by decadal to multi-decadal modes of variability (10 to 50 yr that account for 20–40% of the interannual regional variance. These modes are driven by the vertical supply of dissolved inorganic carbon through the variability of Ekman-induced upwelling and deep-mixing events. Differences in drivers of regional modes of variability stem from the coupling between ocean dynamics variability and the ocean carbon distribution, which is set by large-scale secular ocean circulation.

Soil carbon sequestration, carbon markets, and conservation agriculture practices: A hypothetical examination in Mozambique

Directory of Open Access Journals (Sweden)

Timoteo E. Simone

2017-09-01

Full Text Available Payments for Environmental Services (PES are relatively novel mechanisms whereby the adoption of sustainable management practices by a stakeholder is rewarded by incentives linked to external markets. Adoption of PES for conservation agricultural practices (CAPS by smallholder farmers may provide opportunities to increase household income or cover the technology costs of adoption if the carbon sequestration benefits of CAPS are quantifiable, adoption rates are accelerated and maintained, a mechanism exists whereby carbon sequestration services can be compensated, and carbon offset exchange markets are viable. This research suggests a methodology to examine a PES market for carbon offsets generated by the adoption of CAPS by farmers in Mozambique. Assuming a cumulative adoption of 60% over a 20-year period, revenue from PES market participation to CA adopters was two times higher than revenue earned when disadoption occurred midway through the simulation. Lower adoption targets are associated with higher per household returns when fertilizer rates typical to the region are increased. Establishing and maintaining a sustainable PES system in the study region would require significant investment in time and resources. The lack of on-the-ground institutions or local support for such a program would also challenge successful implementation. Finally, the programs where participant success depends on external markets, such as the hypothetical one suggested here, are subject to the ebb and flow of foreign demand for carbon offsets. Addressing these three broad constraints to a PES/CAPS program in the region would require grass-roots driven policy initiatives with buy-in at multiple social, economic, and political levels.

Deforestation in Amazonia impacts riverine carbon dynamics

Science.gov (United States)

Langerwisch, Fanny; Walz, Ariane; Rammig, Anja; Tietjen, Britta; Thonicke, Kirsten; Cramer, Wolfgang

2016-12-01

Fluxes of organic and inorganic carbon within the Amazon basin are considerably controlled by annual flooding, which triggers the export of terrigenous organic material to the river and ultimately to the Atlantic Ocean. The amount of carbon imported to the river and the further conversion, transport and export of it depend on temperature, atmospheric CO2, terrestrial productivity and carbon storage, as well as discharge. Both terrestrial productivity and discharge are influenced by climate and land use change. The coupled LPJmL and RivCM model system (Langerwisch et al., 2016) has been applied to assess the combined impacts of climate and land use change on the Amazon riverine carbon dynamics. Vegetation dynamics (in LPJmL) as well as export and conversion of terrigenous carbon to and within the river (RivCM) are included. The model system has been applied for the years 1901 to 2099 under two deforestation scenarios and with climate forcing of three SRES emission scenarios, each for five climate models. We find that high deforestation (business-as-usual scenario) will strongly decrease (locally by up to 90 %) riverine particulate and dissolved organic carbon amount until the end of the current century. At the same time, increase in discharge leaves net carbon transport during the first decades of the century roughly unchanged only if a sufficient area is still forested. After 2050 the amount of transported carbon will decrease drastically. In contrast to that, increased temperature and atmospheric CO2 concentration determine the amount of riverine inorganic carbon stored in the Amazon basin. Higher atmospheric CO2 concentrations increase riverine inorganic carbon amount by up to 20 % (SRES A2). The changes in riverine carbon fluxes have direct effects on carbon export, either to the atmosphere via outgassing or to the Atlantic Ocean via discharge. The outgassed carbon will increase slightly in the Amazon basin, but can be regionally reduced by up to 60 % due to

Variations in organic carbon fluxes from Long Island Sound to the Continental Shelf

Science.gov (United States)

Vlahos, P.; Whitney, M. M.

2017-12-01

Organic carbon balances for the Long Island Sound estuary over the years 2009-2012 are presented to assess the particulate and dissolved organic carbon contributions of the estuary to the adjacent shelf waters with respect to the Delaware and Chesapeake. Observations were coupled to a hydrodynamic model (ROMS) for both seasonal and annual estimates. During stratified summer periods, LIS was consistently a net exporter of OC to the continental shelf. LIS annual net carbon export however, varied with river flow. The heterotrophic or autotrophic nature of LIS also shifted seasonally and inter-annually. During the mass balance analysis period LIS ranged between net OC import from the continental shelf and heterotrophy in the lowest river flow year (2012) and net export of OC and autotrophy in the highest flow year (2011). Analysis suggests that LIS switches from net OC import to export when the annual river inputs exceed 19 km3 yr-1. Applying these thresholds to the annual river flow record suggests that net import occurred in 15% of the last 20 years and that LIS usually is a net exporter of OC (85%). Annually averaged LIS carbon export values based on river flow conditions over the last 20 yr are estimated at 56 ± 64 x 106 km3 yr-1. Analysis also suggests that LIS shifts from net heterotrophic to net autotrophic when annual river flow exceeds 26 km3 yr-1 (35% of the last 20 yr). Net heterotrophic conditions are most common, representing 65% of the last 20 yr.

New approach to synthesis of carbon nanotubes

International Nuclear Information System (INIS)

Ha, Jong Keun; Choi, Kyo Hong; Cho, Kwon Koo; Kim, Ki Won; Nam, Tae Hyun; Ahn, Hyo Jun; Ahn, Jou Hyun; Cho, Gyu Bong

2007-01-01

Carbon nanotubes (CNTs) have been synthesized through chemical vapor deposition in argon gas atmosphere using Fe-2.5%Mo alloyed nanoparticles as a catalyst and H 2 /CH 4 gas mixture as a reaction gas. Fe-2.5 wt.%Mo alloyed nanoparticles with average diameter of 7, 20, 45 and 85 nm are prepared by the chemical vapor condensation process using the pyrolysis of iron pentacarbonyl (Fe(CO) 5 ) and molybdenum hexacarbonyl (Mo(CO) 6 ). The morphologies of the CNTs are controlled by adjusting the nanoparticle size, reaction gas ratio and reaction temperature. With decreasing nanoparticle size under the same experimental conditions, the degree of crystalline perfection increases gradually and the morphologies of the carbon nanotubes vary from multi wall carbon nanotubes to single wall carbon nanotubes. Also, the ratio of reaction gas has an effect on the morphology and the degree of crystallinity of CNTs. In this work, it is suggested that morphology, diameter and degree of crystallinity of CNTs could be controlled by adjusting the reaction gas ratio, reaction temperature and catalyst size

Increased field-emission site density from regrown carbon nanotube films

International Nuclear Information System (INIS)

Wang, Y.Y.; Gupta, S.; Liang, M.; Nemanich, R.J.

2005-01-01

Electron field-emission properties of as-grown, etched, and regrown carbon nanotube thin films were investigated. The aligned carbon nanotube films were deposited by the microwave plasma-assisted chemical vapor deposition technique. The surface of the as-grown film contained a carbon nanotube mat of amorphous carbon and entangled nanotubes with some tubes protruding from the surface. Hydrogen plasma etching resulted in the removal of the surface layer, and regrowth on the etched surface displayed the formation of a new carbon nanotube mat. The emission site density and the current-voltage dependence of the field emission from all of the samples were analyzed. The results showed that the as-grown sample had a few strong emission spots and a relatively high emission current density (∼20 μA/cm 2 at 1 V/μm), while the regrown sample exhibited a significantly increased emission site density

Carbonate Mineral Formation on Mars: Clues from Stable Isotope Variation Seen in Cryogenic Laboratory Studies of Carbonate Salts

Science.gov (United States)

Socki, Richard; Niles, Paul B.; Sun, Tao; Fu, Qi; Romanek, Christopher S.; Gibson, Everett K.

2013-01-01

The geologic history of water on the planet Mars is intimately connected to the formation of carbonate minerals through atmospheric CO2 and its control of the climate history of Mars. Carbonate mineral formation under modern martian atmospheric conditions could be a critical factor in controlling the martian climate in a means similar to the rock weathering cycle on Earth. The combination of evidence for liquid water on the martian surface and cold surface conditions suggest fluid freezing could be very common on the surface of Mars. Cryogenic calcite forms readily when a rise in pH occurs as a result of carbon dioxide degassing quickly from freezing Ca-bicarbonate-rich water solutions. This is a process that has been observed in some terrestrial settings such as arctic permafrost cave deposits, lakebeds of the Dry Valleys of Antarctica, and in aufeis (river icings) from rivers of N.E. Alaska. We report here the results of a series of laboratory experiments that were conducted to simulate potential cryogenic carbonate formation on the planet Mars. These results indicate that carbonates grown under martian conditions (controlled atmospheric pressure and temperature) show enrichments from starting bicarbonate fluids in both carbon and oxygen isotopes beyond equilibrium values with average delta13C(DIC-CARB) values of 20.5%0 which exceed the expected equilibrium fractionation factor of [10(sup 3) ln alpha = 13%0] at 0 degC. Oxygen isotopes showed a smaller enrichment with delta18O(H2O-CARB) values of 35.5%0, slightly exceeding the equilibrium fractionation factor of [10(sup 3) ln alpha = 34%0 ] at 0degC. Large kinetic carbon isotope effects during carbonate precipitation could substantially affect the carbon isotope evolution of CO2 on Mars allowing for more efficient removal of 13C from the Noachian atmosphere enriched by atmospheric loss. This mechanism would be consistent with the observations of large carbon isotope variations in martian materials despite the

Microwave plasma chemical synthesis of nanocrystalline carbon film structures and study their properties

Science.gov (United States)

Bushuev, N.; Yafarov, R.; Timoshenkov, V.; Orlov, S.; Starykh, D.

2015-08-01

The self-organization effect of diamond nanocrystals in polymer-graphite and carbon films is detected. The carbon materials deposition was carried from ethanol vapors out at low pressure using a highly non-equilibrium microwave plasma. Deposition processes of carbon film structures (diamond, graphite, graphene) is defined. Deposition processes of nanocrystalline structures containing diamond and graphite phases in different volume ratios is identified. The solid film was obtained under different conditions of microwave plasma chemical synthesis. We investigated the electrical properties of the nanocrystalline carbon films and identified it's from various factors. Influence of diamond-graphite film deposition mode in non-equilibrium microwave plasma at low pressure on emission characteristics was established. This effect is justified using the cluster model of the structure of amorphous carbon. It was shown that the reduction of bound hydrogen in carbon structures leads to a decrease in the threshold electric field of emission from 20-30 V/m to 5 V/m. Reducing the operating voltage field emission can improve mechanical stability of the synthesized film diamond-graphite emitters. Current density emission at least 20 A/cm2 was obtained. Nanocrystalline carbon film materials can be used to create a variety of functional elements in micro- and nanoelectronics and photonics such as cold electron source for emission in vacuum devices, photonic devices, cathodoluminescent flat display, highly efficient white light sources. The obtained graphene carbon net structure (with a net size about 6 μm) may be used for the manufacture of large-area transparent electrode for solar cells and cathodoluminescent light sources

Quantum size effect and thermal stability of carbon-nanotube-based quantum dot

International Nuclear Information System (INIS)

Huang, N.Y.; Peng, J.; Liang, S.D.; Li, Z.B.; Xu, N.S.

2004-01-01

Full text: Based on semi-experience quantum chemical calculation, we have investigated the quantum size effect and thermal stability of open-end carbon nanotube (5, 5) quantum dots of 20 to 400 atoms. It was found that there is a gap in the energy band of all carbon nanotube (5, 5) quantum dots although a (5, 5) carbon nanotube is metallic. The energy gap of quantum dots is much dependent of the number of atoms in a dot, as a result of the quantization rules imposed by the finite scales in both radial and axial directions of a carbon nanotube quantum dot. Also, the heat of formation of carbon nanotube quantum dots is dependent of the size of a quantum dot. (author)

Fractionation between inorganic and organic carbon during the Lomagundi (2.22 2.1 Ga) carbon isotope excursion

Science.gov (United States)

Bekker, A.; Holmden, C.; Beukes, N. J.; Kenig, F.; Eglinton, B.; Patterson, W. P.

2008-07-01

The Lomagundi (2.22-2.1 Ga) positive carbon isotope excursion in shallow-marine sedimentary carbonates has been associated with the rise in atmospheric oxygen, but subsequent studies have demonstrated that the carbon isotope excursion was preceded by the rise in atmospheric oxygen. The amount of oxygen released to the exosphere during the Lomagundi excursion is constrained by the average global fractionation between inorganic and organic carbon, which is poorly characterized. Because dissolved inorganic and organic carbon reservoirs were arguably larger in the Paleoproterozoic ocean, at a time of lower solar luminosity and lower ocean redox state, decoupling between these two variables might be expected. We determined carbon isotope values of carbonate and organic matter in carbonates and shales of the Silverton Formation, South Africa and in the correlative Sengoma Argillite Formation, near the border in Botswana. These units were deposited between 2.22 and 2.06 Ga along the margin of the Kaapvaal Craton in an open-marine deltaic setting and experienced lower greenschist facies metamorphism. The prodelta to offshore marine shales are overlain by a subtidal carbonate sequence. Carbonates exhibit elevated 13C values ranging from 8.3 to 11.2‰ vs. VPDB consistent with deposition during the Lomagundi positive excursion. The total organic carbon (TOC) contents range from 0.01 to 0.6% and δ13C values range from - 24.8 to - 13.9‰. Thus, the isotopic fractionation between organic and carbonate carbon was on average 30.3 ± 2.8‰ ( n = 32) in the shallow-marine environment. The underlying Sengoma shales have highly variable TOC contents (0.14 to 21.94%) and δ13C values (- 33.7 to - 20.8‰) with an average of - 27.0 ± 3.0‰ ( n = 50). Considering that the shales were also deposited during the Lomagundi excursion, and taking δ13C values of the overlying carbonates as representative of the δ13C value of dissolved inorganic carbon during shale deposition, a carbon

Lithium storage performance of carbon nanotubes prepared from polyaniline for lithium-ion batteries

International Nuclear Information System (INIS)

Xiang Xiaoxia; Huang Zhengzheng; Liu Enhui; Shen Haijie; Tian Yingying; Xie Hui; Wu Yuhu; Wu Zhilian

2011-01-01

Highlights: → Polyaniline nanotube is synthesized by the self-assembly method in aqueous media. → Carbon nanotubes were prepared from polyaniline nanotube by physical activation. → Activation leads to large surface area, and surface nitrogen and oxygen functional groups. → Such physical and chemical properties lead to the good electrochemical properties. → After 20 cycles, a reversible capacity of 728 mAh g -1 was obtained. - Abstract: Carbon nanotubes with large surface area and surface nitrogen and oxygen functional groups are prepared by carbonizing and activating of polyaniline nanotubes, which is synthesized by polymerization of aniline with the self-assembly method in aqueous media. The physicochemical properties of the carbon nanotubes are characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller, elemental analyses and X-ray photoelectron spectroscopy measurements. The surface area and pore diameter are 618.9 m 2 g -1 and 3.10 nm. The electrochemical properties of the carbon nanotubes as anode materials in lithium ion batteries are evaluated. At a current density of 100 mA g -1 , the activated carbon nanotube shows an enormously first discharge capacity of about 1370 mAh g -1 and a charge capacity of 907 mAh g -1 . After 20 cycling tests, the activated carbon nanotube retains a reversible capacity of 728 mAh g -1 . These indicate it may be a promising candidate for an anode material for lithium secondary batteries.

Carbons and carbon supported catalysts in hydroprocessing

Energy Technology Data Exchange (ETDEWEB)

Furimsky, Edward

2009-07-01

This book is a comprehensive summary of recent research in the field and covers all areas of carbons and carbon materials. The potential application of carbon supports, particularly those of carbon black (CB) and activated carbon (AC) in hydroprocessing catalysis are covered. Novel carbon materials such as carbon fibers and carbon nano tubes (CNT) are also covered, including the more recent developments in the use of fullerenes in hydroprocessing applications. Although the primary focus of this book is on carbons and carbon supported catalysts, it also identifies the difference in the effect of carbon supports compared with the oxidic supports, particularly that of the Al{sub 2}O{sub 3}. The difference in catalyst activity and stability was estimated using both model compounds and real feeds under variable conditions. The conditions applied during the preparation of carbon supported catalysts are also comprehensively covered and include various methods of pretreatment of carbon supports to enhance catalyst performance. The model compounds results consistently show higher hydrodesulfurization and hydrodeoxygenation activities of carbon supported catalysts than that of the Al{sub 2}O{sub 3} supported catalysts. Also, the deactivation of the former catalysts by coke deposition was much less evident. Chapter 6.3.1.3 is on carbon-supported catalysts: coal-derived liquids.

Carbon Stocks of Fine Woody Debris in Coppice Oak Forests at Different Development Stages

Directory of Open Access Journals (Sweden)

Ender Makineci

2017-06-01

Full Text Available Dead woody debris is a significant component of the carbon cycle in forest ecosystems. This study was conducted in coppice-originated oak forests to determine carbon stocks of dead woody debris in addition to carbon stocks of different ecosystem compartments from the same area and forests which were formerly elucidated. Weight and carbon stocks of woody debris were determined with recent samplings and compared among development stages (diameter at breast height (DBH, D1.3m, namely small-diameter forests (SDF = 0–8 cm, medium diameter forests (MDF = 8–20 cm, and large-diameter forests (LDF = 20–36 cm. Total woody debris was collected in samplings; as bilateral diameters of all woody debris parts were less than 10 cm, all woody parts were in the “fine woody debris (FWD” class. The carbon concentrations of FWD were about 48% for all stages. Mass (0.78–4.92 Mg·ha−1 and carbon stocks (0.38–2.39 Mg·ha−1 of FWD were significantly (p > 0.05 different among development stages. FWD carbon stocks were observed to have significant correlation with D1.3m, age, basal area, and carbon stocks of aboveground biomass (Spearman rank correlation coefficients; 0.757, 0.735, 0.709, and 0.694, respectively. The most important effects on carbon budgets of fine woody debris were determined to be coppice management and intensive utilization. Also, national forestry management, treatments of traditional former coppice, and conversion to high forest were emphasized as having substantial effects.

Carbon pricing. Mobilizing non-state actors on a global issue with local implications

International Nuclear Information System (INIS)

Afriat, Marion; Vaidyula; Manasvini; Alberola, Emilie

2016-09-01

An effective carbon price should send economic and political signals that shift public and private investment to increase the competitiveness of low-carbon solutions (fuels switching, deployment of renewable energy, etc.) and stay below the 2 deg. C trajectory. In 2016, over 40 countries and 20 provinces and cities have established an explicit price on carbon through carbon taxes or emissions trading systems. The choice of the carbon pricing instrument depends largely on the national or local circumstances and priorities. Carbon pricing should not be a stand-alone policy and should be part of a coherent energy and climate policy framework in order to achieve an effective low-carbon transition in all economic sectors. In 2015, $26 billion in government revenue was generated in the world through carbon pricing initiatives. These revenues can be leveraged to yield economic and environmental benefits at the national and local level. The Paris Agreement provides the necessary framework to facilitate the uptake of carbon pricing

Le carbone et l'azote dans les différentes fractions granulométriques ...

African Journals Online (AJOL)

The results show that rice cultivation leads to reduction of soil organic carbon and total nitrogen in the upper horizons (0-20 cm) while an accumulation is observed in lower horizons ... Furthermore, despite the production of methane, irrigated rice system could all the same contribute to atmospheric carbon sequestration.

Binder-less activated carbon electrode from gelam wood for use in supercapacitors

Directory of Open Access Journals (Sweden)

IVANDINI A. TRIBIDASARI

2013-04-01

Full Text Available This work focused on the relation between the porous structure of activated carbon and its capacitive properties. Three types of activated carbon monoliths were used as the electrodes in a half cell electrochemical system. One monolith was produced from activated carbon and considered to be a binder-less electrode. Two others were produced from acid and high pressure steam oxidized activated carbon. The micrographs clearly indicate that three electrodes have different porous structures. Both porosity and surface area of carbons increased due to the formation of grains during oxidation. This fact specified that an acid oxidized carbon monolith will have relatively higher capacitance compared to non-oxidized and steam oxidized monoliths. Maximum capacitance values for acid, steam oxidized and non-oxidized electrodes were 27.68, 2.23 and 1.20 F g-1, respectively.

Xanthobacter sp. C20 contains a novel bioconversion pathway for limonene

OpenAIRE

Werf, M.J. van der; Keijzer, P.M.; Schaft, P.H. van der

2000-01-01

Xanthobacter sp. C20 was isolated from sediment of the river Rhine using cyclohexane as sole source of carbon and energy. Xanthobacter sp. C20 converted both enantiomers of limonene quantitatively into limonene-8,9-epoxide, a not previously described bioconversion product of limonene. With (4R)-limonene, (4R,8R)-limonene-8,9-epoxide was formed as the only reaction product, while (4S)-limonene was converted into a (78:22) mixture of (4S,8R)- and (4S,8S)-limonene-8,9-epoxide. Cytochrome P-450 w...

CI, CII, and CO as tracers of gas phase carbon

International Nuclear Information System (INIS)

Keene, J.

1990-01-01

In the dense interstellar medium, we find that about 20 percent of the total carbon abundance is in the form of CO, about 3 percent in C I , and 100 percent in C II with uncertainties of factors of order 2. The abundance of other forms of gaseous carbon is negligible. CO is widespread throughout molecular clouds as is C I . C II has only been observed near bright star-formation regions so far because of its high excitation energy. Further from ultraviolet sources it may be less abundant. Altogether we have accounted for about 1/3 of the total carbon abundance associated with dense molecular clouds. Since the other gaseous forms are thought to have negligible abundances, the rest of the carbon is probably in solid form

The Impact of Surface Chemistry on Bio-derived Carbon Performance as Supercapacitor Electrodes

KAUST Repository

Alshareef, Husam N.

2016-12-23

In this study, we demonstrate that highly functionalized and porous carbons can be derived from palm-leaf waste using the template-free facile synthesis process. The derived carbons have high content of nitrogen dopant, high surface area, and various defects. Moreover, these carbons exhibit a high electrical conductivity (107 S m−1). Thanks to the high content of edge N (64.3%) and highly microporous nature (82% of microspores), these biomass-derived carbons show promising performance when used as supercapacitor electrodes. To be specific, these carbonaceous materials show a specific capacitance as high as 197 and 135 F g−1 at 2 and 20 A g−1 in three-electrode configuration, respectively. Furthermore, the symmetrical cells using palm-leaf-derived carbon show an energy density of 8.4 Wh Kg−1 at a power density of 0.64 kW Kg−1, with high cycling life stability (∼8% loss after 10,000 continuous charge–discharge cycles at 20 A g−1). Interestingly, as the power density increases from 4.4 kW kg−1 to 36.8 kW kg−1, the energy density drops slowly from 8.4 Wh kg−1 to 3.4 Wh kg−1. Getting such extremely high power density without significant loss of energy density indicates that these palm-leaf-derived carbons have excellent electrode performance as supercapacitor electrodes.

The Impact of Surface Chemistry on Bio-derived Carbon Performance as Supercapacitor Electrodes

KAUST Repository

Alshareef, Husam N.; Whitehair, Daniel; Xia, Chuan

2016-01-01

In this study, we demonstrate that highly functionalized and porous carbons can be derived from palm-leaf waste using the template-free facile synthesis process. The derived carbons have high content of nitrogen dopant, high surface area, and various defects. Moreover, these carbons exhibit a high electrical conductivity (107 S m−1). Thanks to the high content of edge N (64.3%) and highly microporous nature (82% of microspores), these biomass-derived carbons show promising performance when used as supercapacitor electrodes. To be specific, these carbonaceous materials show a specific capacitance as high as 197 and 135 F g−1 at 2 and 20 A g−1 in three-electrode configuration, respectively. Furthermore, the symmetrical cells using palm-leaf-derived carbon show an energy density of 8.4 Wh Kg−1 at a power density of 0.64 kW Kg−1, with high cycling life stability (∼8% loss after 10,000 continuous charge–discharge cycles at 20 A g−1). Interestingly, as the power density increases from 4.4 kW kg−1 to 36.8 kW kg−1, the energy density drops slowly from 8.4 Wh kg−1 to 3.4 Wh kg−1. Getting such extremely high power density without significant loss of energy density indicates that these palm-leaf-derived carbons have excellent electrode performance as supercapacitor electrodes.

Environmental effects of increased atmospheric carbon dioxide

International Nuclear Information System (INIS)

Soon, W.; Baliunas, S.L.; Robinson, A.B.; Robinson, Z.W.

1999-01-01

A review of the literature concerning the environmental consequences of increased levels of atmospheric carbon dioxide leads to the conclusion that increases during the 20th century have produced no deleterious effects upon global climate or temperature. Increased carbon dioxide has, however, markedly increased plant growth rates as inferred from numerous laboratory and field experiments. There is no clear evidence, nor unique attribution, of the global effects of anthropogenic CO 2 on climate. Meaningful integrated assessments of the environmental impacts of anthropogenic CO 2 are not yet possible because model estimates of global and regional climate changes on interannual, decadal and centennial timescales remain highly uncertain.(author)

Process for derivatizing carbon nanotubes with diazonium species

Science.gov (United States)

Tour, James M. (Inventor); Bahr, Jeffrey L. (Inventor); Yang, Jiping (Inventor)

2007-01-01

The invention incorporates new processes for the chemical modification of carbon nanotubes. Such processes involve the derivatization of multi- and single-wall carbon nanotubes, including small diameter (ca. 0.7 nm) single-wall carbon nanotubes, with diazonium species. The method allows the chemical attachment of a variety of organic compounds to the side and ends of carbon nanotubes. These chemically modified nanotubes have applications in polymer composite materials, molecular electronic applications and sensor devices. The methods of derivatization include electrochemical induced reactions thermally induced reactions (via in-situ generation of diazonium compounds or pre-formed diazonium compounds), and photochemically induced reactions. The derivatization causes significant changes in the spectroscopic properties of the nanotubes. The estimated degree of functionality is ca. 1 out of every 20 to 30 carbons in a nanotube bearing a functionality moiety. Such electrochemical reduction processes can be adapted to apply site-selective chemical functionalization of nanotubes. Moreover, when modified with suitable chemical groups, the derivatized nanotubes are chemically compatible with a polymer matrix, allowing transfer of the properties of the nanotubes (such as, mechanical strength or electrical conductivity) to the properties of the composite material as a whole. Furthermore, when modified with suitable chemical groups, the groups can be polymerized to form a polymer that includes carbon nanotubes ##STR00001##.

Mineral Carbonation Employing Ultramafic Mine Waste

Science.gov (United States)

Southam, G.; McCutcheon, J.; Power, I. M.; Harrison, A. L.; Wilson, S. A.; Dipple, G. M.

2014-12-01

wetland (up to 1000 ppm), and dissolved inorganic carbon (> 20 mM C) were ideal for carbonate precipitation. Under optimum nutrient and magnesium inputs, a mass balance calculation using water chemistry data and hydromagnesite as the sole mineral product resulted in a carbon sequestration rate of 61 t C/ha/year.

Carbon/Carbon Pistons for Internal Combustion Engines

Science.gov (United States)

Taylor, A. H.

1986-01-01

Carbon/carbon piston performs same function as aluminum pistons in reciprocating internal combustion engines while reducing weight and increasing mechanical and thermal efficiencies of engine. Carbon/carbon piston concept features low piston-to-cylinder wall clearance - so low piston rings and skirts unnecessary. Advantages possible by negligible coefficient of thermal expansion of carbon/carbon.

Graphitization kinetics of fluidized-bed pyrolytic carbons

International Nuclear Information System (INIS)

Beatty, R.L.

1975-08-01

Graphitization of 12 fluidized-bed pyrocarbons was studied as a function of heat-treatment time and temperature (1350 to 3000 0 C) to investigate the effect of initial microstructure on the graphitization process. The term ''graphitization'' is defined to include any thermally induced structural change, whether or not any layer stacking order is attained. A broad range of CVD microstructures was prepared at temperatures from 1150 to 1900 0 C and various propylene and methane concentrations. The twelve carbons spanned a wide range of graphitizabilities, primarily as a function of deposition temperature. Hydrocarbon concentration was of much less importance except for deposition at 1900 0 C. Hydrogen content of the as-deposited carbons decreased with increasing temperature of deposition, and initial graphitization behavior of the low-temperature carbons appeared to be related to hydrogen content and evolution. Rates of change in the parameters varied widely throughout the range of heat-treatment times (HTt) and temperatures (HTT) for the different carbons showing differences between the more graphitizable or ''soft'' carbons from the nongraphitizing or ''hard'' carbons. ΔH for nongraphitizing carbons was 175 +- 15 kcal below 1950 0 C, 240 +- 35 kcal at 1950 to 2700 0 C, and 330 +- 20 kcal above 2700 0 C. For graphitizing carbons deposited at 1150 0 C, values near 245 kcal were obtained from anti chi data for the HTT range 1350 to 1650 0 C, while densification data yielded values of about 160 kcal in the same range. The behaviors observed for graphitizable carbons above 2000 0 C are consistent with literature. Different kinetic behaviors below 2000 0 C were shown to be due to different initial microstructures as well as to different parameters measured. (U.S.)

Hydrogen storage in nanoporous carbon materials: myth and facts.

Science.gov (United States)

Kowalczyk, Piotr; Hołyst, Robert; Terrones, Mauricio; Terrones, Humberto

2007-04-21

We used Grand canonical Monte Carlo simulation to model the hydrogen storage in the primitive, gyroid, diamond, and quasi-periodic icosahedral nanoporous carbon materials and in carbon nanotubes. We found that none of the investigated nanoporous carbon materials satisfy the US Department of Energy goal of volumetric density and mass storage for automotive application (6 wt% and 45 kg H(2) m(-3)) at considered storage condition. Our calculations indicate that quasi-periodic icosahedral nanoporous carbon material can reach the 6 wt% at 3.8 MPa and 77 K, but the volumetric density does not exceed 24 kg H(2) m(-3). The bundle of single-walled carbon nanotubes can store only up to 4.5 wt%, but with high volumetric density of 42 kg H(2) m(-3). All investigated nanoporous carbon materials are not effective against compression above 20 MPa at 77 K because the adsorbed density approaches the density of the bulk fluid. It follows from this work that geometry of carbon surfaces can enhance the storage capacity only to a limited extent. Only a combination of the most effective structure with appropriate additives (metals) can provide an efficient storage medium for hydrogen in the quest for a source of "clean" energy.

Carbon dioxide conversion over carbon-based nanocatalysts.

Science.gov (United States)

Khavarian, Mehrnoush; Chai, Siang-Piao; Mohamed, Abdul Rahman

2013-07-01

The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity.

Carbon stars with alpha-C:H emission

Science.gov (United States)

Gerbault, Florence; Goebel, John H.

1989-01-01

Many carbon stars in the IRS low resolution spectra (LRS) catalog were found which display emission spectra that compare favorable with the absorption spectrum of alpha-C:H. These stars have largely been classified as 4X in the LRS which has led to their interpretation by others in terms of displaying a mixture of the UIRF's 8.6 micron band and SiC at 11.5 microns. It was also found that many of these stars have a spectral upturn at 20+ microns which resembles the MgS band seen in carbon stars and planetary nebulae. It was concluded that this group of carbon stars will evolve into planetary nebulae like NGC 7027 and IC 418. In the presence of hard ultraviolet radiation the UIRF's will light up and be displayed as narrow emission bands on top of the broad alpha-C:H emission bands.

Tuning the Slide-Roll Motion Mode of Carbon Nanotubes via Hydroxyl Groups

Science.gov (United States)

Li, Rui; Wang, Shiwei; Peng, Qing

2018-05-01

Controlling the motion of carbon nanotubes is critical in manipulating nanodevices, including nanorobots. Herein, we investigate the motion behavior of SWCNT (10,10) on Si substrate utilizing molecular dynamics simulations. We show that hydroxyl groups have sensitive effect on the carbon nanotube's motion mode. When the hydroxyl groups' ratio on carbon nanotube and silicon substrate surfaces is larger than 10 and 20%, respectively, the motion of carbon nanotube transforms from sliding to rolling. When the hydroxyl groups' ratio is smaller, the slide or roll mode can be controlled by the speed of carbon nanotube, which is ultimately determined by the competition between the interface potential energy and kinetic energy. The change of motion mode holds true for different carbon nanotubes with hydroxyl groups. The chirality has little effect on the motion behavior, as opposed to the diameter, attributed to the hydroxyl groups' ratio. Our study suggests a new route to control the motion behavior of carbon nanotube via hydroxyl groups.

Three dimensional carbon-bubble foams with hierarchical pores for ultra-long cycling life supercapacitors.

Science.gov (United States)

Wang, Bowen; Zhang, Weigang; Wang, Lei; Wei, Jiake; Bai, Xuedong; Liu, Jingyue; Zhang, Guanhua; Duan, Huigao

2018-07-06

Design and synthesis of integrated, interconnected porous structures are critical to the development of high-performance supercapacitors. We develop a novel and facile synthesis technic to construct three-dimensional carbon-bubble foams with hierarchical pores geometry. The carbon-bubble foams are fabricated by conformally coating, via catalytic decomposition of ethanol, a layer of carbon coating onto the surfaces of pre-formed ZnO foams and then the removal of the ZnO template by a reduction-evaporation process. Both the wall thickness and the pore size can be well tuned by adjusting the catalytic decomposition time and temperature. The as-synthesized carbon-bubble foams electrode retains 90.3% of the initial capacitance even after 70 000 continuous cycles under a high current density of 20 A g -1 , demonstrating excellent long-time electrochemical and cycling stability. The symmetric device displays rate capability retention of 81.8% with the current density increasing from 0.4 to 20 A g -1 . These achieved electrochemical performances originate from the unique structural design of the carbon-bubble foams, which provide not only abundant transport channels for electron and ion but also high active surface area accessible by the electrolyte ions.

Application of Carbon Composite Bricks for Blast Furnace Hearth

Science.gov (United States)

Zuo, Haibin; Wang, Cong; Zhang, Jianliang; Zhao, Yongan; Jiao, Kexin

Traditional refractory materials for blast furnace hearth lining are mainly composed of carbon bricks and the ceramic cup. However, these materials can't meet the demands for long service life design of blast furnaces. In this paper, a new refractory called carbon composite brick (CCB) was introduced, which combined the advantages of carbon bricks and the ceramic cup. In this case, the resistance of the CCB against corrosion was equal to the ceramic cup and the thermal conductivity of the CCB was equal to carbon bricks. From the results of more than 20 blast furnaces, the CCB could be well used in small blast furnaces and large blast furnaces. In the bad condition of low grade burden and high smelting intensity, the CCB gave full play to the role of cooling system, and effectively resisted the erosion of hot metal to improve the service life of blast furnaces.

27.12 MHz plasma generation in supercritical carbon dioxide

International Nuclear Information System (INIS)

Kawashima, Ayato; Toyota, Hiromichi; Nomura, Shinfuku; Takemori, Toshihiko; Mukasa, Shinobu; Maehara, Tsunehiro; Yamashita, Hiroshi

2007-01-01

An experiment was conducted for generating high-frequency plasma in supercritical carbon dioxide; it is expected to have the potential for applications in various types of practical processes. It was successfully generated at 6-20 MPa using electrodes mounted in a supercritical cell with a gap of 1 mm. Emission spectra were then measured to investigate the physical properties of supercritical carbon dioxide plasma. The results indicated that while the emission spectra for carbon dioxide and carbon monoxide could be mainly obtained at a low pressure, the emission spectra for atomic oxygen could be obtained in the supercritical state, which increased with the pressure. The temperature of the plasma in supercritical state was estimated to be approximately 6000-7000 K on the assumption of local thermodynamic equilibrium and the calculation results of thermal equilibrium composition in this state showed the increase of atomic oxygen by the decomposition of CO 2

Cathode spot movements along the carbon fibres in carbon/carbon composites

International Nuclear Information System (INIS)

Zhang Chengyu; Qiao Shengru; Yang Zhimao; Ding Bingjun

2007-01-01

The cathode spot movements on a polyacrilonitrile (PAN)-based carbon felt reinforced C/C composite and a three dimensional PAN-based carbon fibre reinforced C/C composite (3D-C/C) were investigated by a scanning electron microscope and a digital high-speed video camera. It was found that the carbon fibres have a higher ability to withstand the vacuum arc erosion than the carbon matrix. The cathode spot walks on the matrix, rather than on the carbon fibres. The cathode spot motion is controlled by the architecture of carbon fibres in C/C. The cathode spots move along the carbon fibres by a step-by-step manner rather than a random walk. The cathode spot tracks spread over a wide zone on the 3D-C/C surface parallel to the carbon fibre. The average arc spreading velocity is estimated to be about 0.9 m s -1 and the transient arc spreading velocity is in the range of 0.54-4.5 m s -1

Some Observations on Carbon Nano tubes Susceptibility to Cell Phagocytosis

International Nuclear Information System (INIS)

Fraczek-Szczypta, A.; Menaszek, E.; Blazewicz, S.; Menaszek, E.

2011-01-01

The aim of this study was to assess the influence of different types of carbon nano tubes (CNTs) on cell phagocytosis. Three kinds of carbon nano tubes: single-walled carbon nano horns (SWCNHs), multi walled carbon nano tubes (MWCNTs), and ultra-long single-walled carbon nano tubes (ULSWCNTs) before and after additional chemical functionalization were seeded with macrophage cell culture. Prior to biological testing, the CNTs were subjected to dispersion process with the use of phosphate buffered solution (PBS) and PBS containing surfactant (Tween 20) or dimethyl sulfoxide (DMSO). The results indicate that the cells interaction with an individual nano tube is entirely different as compared to CNTs in the form of aggregate. The presence of the surfactant favors the CNTs dispersion in culture media and facilitates phagocytosis process, while it has disadvantageous influence on cells morphology. The cells phagocytosis is a more effective for MWCNTs and SWCNHs after their chemical functionalization. Moreover, these nano tubes were well dispersed in culture media without using DMSO or surfactant. The functionalized carbon nano tubes were easily dispersed in pure PBS and seeded with cells

Adsorption of malachite green onto carbon prepared from borassus bar

International Nuclear Information System (INIS)

Arivoli, S; Hema, M; Prasath, P Martin Deva

2009-01-01

An activated carbon prepared from Borassus bark, a low-cost source, by sulphuric acid activation, was tested for its ability to remove malachite green in aqueous solution. The parameters studied included contact time, initial dye concentration, carbon dose, pH, and temperature. The adsorption followed first order rate equation and the rate was mainly controlled by intra-particle diffusion. Freundlich and Langmuir isotherm models were applied to the equilibrium data. The adsorption capacities (Qm) obtained from the Langmuir isotherm plots were 20.70, 20.25, 19.76, and 19.34 mg/g at 30, 40, 50, and 60 degree C, respectively, at an initial pH of 6.0. The temperature variation study showed that the malachite green adsorption was endothermic and spontaneous with increased randomness at the solid solution interface. (author)

Radiation damage in carbon-carbon composites

International Nuclear Information System (INIS)

Burchell, T.D.; Eartherly, W.P.; Nelson, G.E.

1992-01-01

Graphite and carbon-carbon composite materials are widely used in plasma facing applications in current Tokamak devices such as TFTR and DIIID in the USA, JET, Tore Supra and TEXTOR in Europe, and JT-60U in Japan. Carbon-carbon composites are attractive choices for Tokamak limiters and diverters because of their low atomic number, high thermal shock resistance, high melting point, and high thermal conductivity. Next generation machines such as the International Thermonuclear Experimental Reactor (ITER) will utilize carbon-carbon composites in their first wall and diverter. ITER will be an ignition machine and thus will produce substantial neutron fluences from the D-T fusion reaction. The resultant high energy neutrons will cause carbon atom displacements in the plasma facing materials which will markedly affect their structure and physical properties. The effect of neutron damage on graphite has been studied for over forty years. Recently the effects of neutron irradiation on the fusion relevant graphite GraphNOL N3M was reviewed. In contrast to graphite, relatively little work has been performed to elucidate the effects of neutron irradiation on carbon-carbon composites. The results of our previous irradiation experiments have been published elsewhere. Here the irradiation induced dimensional changes in 1D, 2D, and 3D carbon-carbon composites are reported for fluences up to 4.7 dpa at an irradiation temperature of 600 degree C

Destruction of Refractory Carbon in Protoplanetary Disks

Energy Technology Data Exchange (ETDEWEB)

Anderson, Dana E.; Blake, Geoffrey A. [Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Bergin, Edwin A. [Department of Astronomy, University of Michigan, 1085 S. University, Ann Arbor, MI 48109-1107 (United States); Ciesla, Fred J. [Department of Geophysical Sciences, The University of Chicago, 5734 South Ellis Ave., Chicago, IL 60637 (United States); Visser, Ruud [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748, Garching (Germany); Lee, Jeong-Eun [School of Space Research, Kyung Hee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104 (Korea, Republic of)

2017-08-10

The Earth and other rocky bodies in the inner solar system contain significantly less carbon than the primordial materials that seeded their formation. These carbon-poor objects include the parent bodies of primitive meteorites, suggesting that at least one process responsible for solid-phase carbon depletion was active prior to the early stages of planet formation. Potential mechanisms include the erosion of carbonaceous materials by photons or atomic oxygen in the surface layers of the protoplanetary disk. Under photochemically generated favorable conditions, these reactions can deplete the near-surface abundance of carbon grains and polycyclic aromatic hydrocarbons by several orders of magnitude on short timescales relative to the lifetime of the disk out to radii of ∼20–100+ au from the central star depending on the form of refractory carbon present. Due to the reliance of destruction mechanisms on a high influx of photons, the extent of refractory carbon depletion is quite sensitive to the disk’s internal radiation field. Dust transport within the disk is required to affect the composition of the midplane. In our current model of a passive, constant- α disk, where α = 0.01, carbon grains can be turbulently lofted into the destructive surface layers and depleted out to radii of ∼3–10 au for 0.1–1 μ m grains. Smaller grains can be cleared out of the planet-forming region completely. Destruction may be more effective in an actively accreting disk or when considering individual grain trajectories in non-idealized disks.

Nitroreductase catalyzed biotransformation of CL-20

International Nuclear Information System (INIS)

Bhushan, Bharat; Halasz, Annamaria; Hawari, Jalal

2004-01-01

Previously, we reported that a salicylate 1-monooxygenase from Pseudomonas sp. ATCC 29352 biotransformed CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane) (C 6 H 6 N 12 O 12 ) and produced a key metabolite with mol. wt. 346Da corresponding to an empirical formula of C 6 H 6 N 10 O 8 which spontaneously decomposed in aqueous medium to produce N 2 O, NH4+, and HCOOH [Appl. Environ. Microbiol. (2004)]. In the present study, we found that nitroreductase from Escherichia coli catalyzed a one-electron transfer to CL-20 to form a radical anion (CL-20 - ) which upon initial N-denitration also produced metabolite C 6 H 6 N 10 O 8 . The latter was tentatively identified as 1,4,5,8-tetranitro-1,3a,4,4a,5,7a,8,8a-octahydro-diimidazo[4,5-b:4',5'-e] pyrazine [IUPAC] which decomposed spontaneously in water to produce glyoxal (OHCCHO) and formic acid (HCOOH). The rates of CL-20 biotransformation under anaerobic and aerobic conditions were 3.4+/-0.2 and 0.25+/-0.01nmolmin -1 mg of protein -1 , respectively. The product stoichiometry showed that each reacted CL-20 molecule produced about 1.8 nitrite ions, 3.3 molecules of nitrous oxide, 1.6 molecules of formic acid, 1.0 molecule of glyoxal, and 1.3 ammonium ions. Carbon and nitrogen products gave mass-balances of 60% and 81%, respectively. A comparative study between native-, deflavo-, and reconstituted-nitroreductase showed that FMN-site was possibly involved in the biotransformation of CL-20

THE Eucalyptus sp. AGE PLANTATIONS INFLUENCING THE CARBON STOCKS

Directory of Open Access Journals (Sweden)

Charlote Wink

2013-06-01

Full Text Available http://dx.doi.org/10.5902/198050989279The tree growth and biomass accumulation, as well as the maintenance of forest residue at the soil surface can act in the removal of carbon from the atmosphere through the cycling process of plant material. The objective was to study the influence of Eucalyptus sp. Plantations with 20, 44 and 240 months of age on the variation of carbon in soil and biomass. The carbon in the soil depth was determined by CHNS auto-analyzer and carbon in the vegetation was determined by the biomass in each forest, considering a factor of 0.45 of the dry mass. We determined the density and particle size distribution of soil. For the comparison between plantations, there was analysis of variance and comparison of means of carbon in vegetation and soil, considering the 5% level of probability. The carbon content and stock in the soil were low, indicating that a natural feature of the category of Paleuldt, or the growth of eucalyptus forests, replacing the field native vegetation did not aggregate a significant increase in the carbon. Although, there was a significant increase carbon in aboveground biomass. It includes forest biomass and litter. So, despite the values ​​of carbon stocks are low, it identified a greater average total in the soil compared to the stock aboveground. Furthermore, this increase aboveground (tree and litter compartments can be considered significant between the eucalyptus plantations of different ages.

More About Arc-Welding Process for Making Carbon Nanotubes

Science.gov (United States)

Benavides, Jeanette M.; Leidecker, Henning

2005-01-01

High-quality batches of carbon nanotubes are produced at relatively low cost in a modified atmospheric-pressure electric-arc welding process that does not include the use of metal catalysts. What would normally be a welding rod and a weldment are replaced by an amorphous carbon anode rod and a wider, hollow graphite cathode rod. Both electrodes are water-cooled. The cathode is immersed in ice water to about 0.5 cm from the surface. The system is shielded from air by flowing helium during arcing. As the anode is consumed during arcing at 20 to 25 A, it is lowered to maintain it at an approximately constant distance above the cathode. The process causes carbon nanotubes to form on the lowest 5 cm of the anode. The arcing process is continued until the anode has been lowered to a specified height. The nanotube-containing material is then harvested. The additional information contained in the instant report consists mostly of illustrations of carbon nanotubes and a schematic diagram of the arc-welding setup, as modified for the production of carbon nanotubes.

Carbon, chromium and molybdenum contents

International Nuclear Information System (INIS)

Sinatora, A; Goldenstein, H.; Mei, P.R.; Albertin, E.; Fuoco, R.; Mariotto, C.L.

1992-01-01

This work describes solidification experiments on white cast iron, with 15 and 20% of chromium, 2.3, 3.0 and 3.6 % of carbon and 0.0, 1.5 and 2.5 % of molybdenum in test de samples with 30 mm diameter. Measurements were performed on the austenite and eutectic formation arrests, the number of the eutectic carbide particles relative to the total and the eutectic volumes, and the volume fraction of the primary austenite

A co-confined carbonization approach to aligned nitrogen-doped mesoporous carbon nanofibers and its application as an adsorbent

International Nuclear Information System (INIS)

Chen, Aibing; Liu, Chao; Yu, Yifeng; Hu, Yongqi; Lv, Haijun; Zhang, Yue; Shen, Shufeng; Zhang, Jian

2014-01-01

Highlights: • MCNFs were synthesized by a co-confined carbonization method. • The diameter size of MCNFs with bimodal mesoporous structure can be modulated. • The obtained MCNFs manifest better adsorption capacity for SO 2 , CO 2 and Cd 2+ . - Abstract: Nitrogen-doped carbon nanofibers (MCNFs) with an aligned mesoporous structure were synthesized by a co-confined carbonization method using anodic aluminum oxide (AAO) membrane and tetraethylorthosilicate (TEOS) as co-confined templates and ionic liquids as the precursor. The as-synthesized MCNFs with the diameter of 80–120 nm possessed a bulk nitrogen content of 5.3 wt% and bimodal mesoporous structure. The nitrogen atoms were mostly bound to the graphitic network in two forms, i.e. pyridinic and pyrrolic nitrogen, providing adsorption sites for acidic gases like SO 2 and CO 2 . Cyclic experiments revealed a considerable stability of MCNFs over 20 runs of SO 2 adsorption and 15 runs for CO 2 adsorption. The MCNFs also have a preferable adsorption performance for Cd 2+

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

Science.gov (United States)

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

[Soil organic carbon sequestration rate and its influencing factors in farmland of Guanzhong Plain: a case study in Wugong County, Shannxi Province].

Science.gov (United States)

Zhang, Xiao-Wei; Xu, Ming-Xiang

2013-07-01

Take Wugong County as an example, soil carbon storage and soil carbon sequestration rate were calculated, the change law of farmland soil organic carbon was explored, and the relationship of farmland soil organic carbon and natural factors, human factors was further revealed. The results of the study showed that: (1) The soil organic carbon contents in 80% of the sampling sites were in the range of 8.0-12.0 g x kg(-1), and the organic carbon contents in 0-20 cm soils showed a normal distribution. (2) In 2011, the organic carbon density of the 0-20 cm farmland soil was 26.3 t x hm(-2), below the national average soil organic carbon density (33.45 t x hm(-2)) of the arable layer. In the last 30 years, the soil carbon sequestration rate in the 0-20 cm layer was 71.3 kg x (hm2 x a)(-1), and in the past five years, the carbon sequestration rate was 480 kg x (hm x a)(-1). The recent carbon sequestration rate was higher than the national average soil carbon sequestration rate of the arable layer [380.78 kg x (hm2 x a)(-1)]. (3) In the semi-humid plain region, soil organic carbon was mainly affected by soil types, landform types, organic fertilizer. Soil types accounted for 30.2% of the organic carbon variability; the landform types and the organic fertilizer could explain 37.7% and 32.1%, respectively. The results of the comprehensive analysis showed that the farmland soil organic carbon density of Wugong County in the past 30 years is increasing, and this probably relies on the utilization of chemical fertilizer and the returning straw. Further study should be conducted on the impact of the chemical fertilizer and returning straw.

Analysis of the radial distribution curves of partially ordered condensed carbon films

International Nuclear Information System (INIS)

Palatnik, L.S.; Derevyanchenko, A.S.; Nechitajlo, A.A.; Stetsenko, A.N.; Gorbenko, N.I.

1977-01-01

The Fourier analysis of the electron scattering curves has been carried out to determine the short-range order structure of carbon condensates. The intensity curves for carbon films condensed in a approximately 10 -6 Torr vacuum upon a substrate heated up to 600 deg C were obtained by diffraction techniques with filtration of the inelastic scattered electron background. The radial distribution curve errors were analyzed and quantified with the aid of a computer to determine the short-range order of the condensed carbon. It has been shown that carbon films consist of regions measuring approximately 20 A formed by parallelly packed graphite nets with azimuthal orientation different from that in ideal graphite crystals

Sociopolitical drivers in the development of deliberate carbon storage

Science.gov (United States)

Stephens, Jennie C.

The idea of engineering the storage of carbon released from fossil fuel burning in reservoirs other than the atmosphere has developed in the past 20 years from an obscure idea to an increasingly recognized potential approach that could be an important contributor to stabilizing atmospheric carbon dioxide (CO2) concentrations. Despite the intense application of scientific and technological expertise to the development of options for deliberate carbon storage, nontechnical factors play an important role. This chapter identifies sociopolitical, nontechnical factors that have contributed to the development of ideas and technologies associated with deliberate carbon storage. Broadly, interest in deliberate storage has expanded in response to increasing societal attention to reducing CO2 emissions for climate change mitigation. Specific societal groups, or stakeholders, which have contributed to the recent focus on carbon storage include the fossil fuel industry that has been shifting to a strategy of confronting rather than denying the CO2-climate change connection, a scientific community motivated by an increased sense of urgency of the need to reduce atmospheric CO2 concentrations, the general public with little knowledge about or awareness of carbon storage, and environmental advocacy groups that have demonstrated some divergence in levels of support for deliberate carbon storage. Among the policy mechanisms that have provided incentives for deliberate carbon storage are national accounting of carbon sources and sinks and carbon taxes. Another driver with particular importance in the United States is the political preference of some politicians to support development of advanced technologies for climate change mitigation rather than supporting mandatory CO2 regulations.

Short Term Electric Production Technology Switching Under Carbon Cap and Trade

Directory of Open Access Journals (Sweden)

Donald F. Larson

2012-10-01

Full Text Available This study examines fuel switching in electricity production following the introduction of the European Union’s Emissions Trading System (EU ETS for greenhouse gas emissions. A short-run restricted cost equation is estimated with carbon permits, high-carbon fuels, and low carbon fuels as variable inputs. Shadow values and substitution elasticities for carbon-free energy resources from nuclear, hydroelectric and renewable sources are imputed from the cost equation. The empirical analysis examines 12 European countries using monthly data on fuel use, prices, and electricity generation during the first phase of the European Emissions Trading System. Despite low emission permit prices, this study finds statistically significant substitution between fossil fuels and carbon free sources of energy for electric power production. Significant substitution between fossil fuels and nuclear energy also was found. Still, while 18 of the 20 substitution elasticities are statistically significant, they are all less than unity, consistent with limited substitution. Overall, these results suggest that prices for carbon emission permits relative to prices for carbon and carbon free sources of energy do matter but that electric power producers have limited operational flexibility in the short-run to satisfy greenhouse gas emission limits.

Preparation of ultrasmall porous carbon nanospheres by reverse microemulsion-hydrothermal method

Science.gov (United States)

Wang, Jiasheng; Zhao, Yahong; Wang, Wan-Hui; Bao, Ming

Porous carbon nanospheres (CNSs) have wide applications. A big challenge in materials science is synthesis of discrete ultrasmall porous carbon nanospheres. Herein, we report a facile reverse microemulsion-hydrothermal method to prepare discrete porous CNSs. The obtained CNSs possess an average diameter of 20nm and pores of 0.7nm and 3.4nm. Our work has provided a convenient method for the controllable synthesis of ultrasmall porous CNSs with potential applications.

Photosynthetic carbon metabolism in freshwater phytoplankton

International Nuclear Information System (INIS)

Groeger, A.W.

1986-01-01

Photosynthetic carbon metabolism of natural assemblages of freshwater phytoplankton was measured by following the flow of inorganic 14 C into the photosynthetic end products polysaccharide protein, lipid, and soluble metabolites. Data were collected from a wide range of physical, chemical, and trophic conditions in six southern United States reservoirs, with the primary environmental variables of interest being light intensity and nutrient supply. Polysaccharide and protein were consistently the primary products of photosynthetic carbon metabolism, comprising an average of 70% of the total carbon fixation over a wide range of light intensities. Polysaccharide was quantitatively more important at higher light intensities, and protein at lower light intensities, as light intensity varied both with depth within the water column and over diurnal cycles. Polysaccharide synthesis was more variable over the diurnal period than was protein synthesis. Phytoplankton in the downlake epilimnion of Normandy Lake, a central Tennessee reservoir, responded to summer nitrogen (N) deficiency by increasing relative rates of lipid synthesis from 10-15% to 20-25% of the total photosynthetic carbon fixation. Phytoplankton in more nitrogen-sufficient areas of the reservoir maintained lower rates of lipid synthesis throughout the summer. These results document the occurrence in nature of a relationship between N-deficiency and increased lipid synthesis previously observed only in laboratory algal culture studies

Managing carbon sinks by changing rotation length in European forests

International Nuclear Information System (INIS)

Kaipainen, Terhi; Liski, Jari; Pussinen, Ari; Karjalainen, Timo

2004-01-01

Elongation of rotation length is a forest management activity countries may choose to apply under Article 3.4 of the Kyoto Protocol to help them meet their commitments for reduction of greenhouse gas emissions. We used the CO2FIX model to analyze how the carbon stocks of trees, soil and wood products depend on rotation length in different European forests. Results predicted that the carbon stock of trees increased in each forest when rotation length was increased, but the carbon stock of soil decreased slightly in German and Finnish Scots pine forests; the carbon stock of wood products also decreased slightly in cases other than the Sitka spruce forest in UK. To estimate the efficiency of increasing rotation length as an Article 3.4 activity, we looked at changes in the carbon stock of trees resulting from a 20-year increase in current rotation lengths. To achieve the largest eligible carbon sink mentioned in Article 3.4 of the Kyoto Protocol, the rotation lengths need to be increased on areas varying from 0.3 to 5.1 Mha depending on the forest. This would in some forests cause 1-6% declines in harvesting possibilities. The possible decreases in the carbon stock of soil indicate that reporting the changes in the carbon stocks of forests under Article 3.4 may require measuring soil carbon

Involvement of H(+)-ATPase and carbonic anhydrase in inorganic carbon uptake for endosymbiont photosynthesis.

Science.gov (United States)

Furla, P; Allemand, D; Orsenigo, M N

2000-04-01

Symbiotic cnidarians absorb inorganic carbon from seawater to supply intracellular dinoflagellates with CO(2) for their photosynthesis. To determine the mechanism of inorganic carbon transport by animal cells, we used plasma membrane vesicles prepared from ectodermal cells isolated from tentacles of the sea anemone, Anemonia viridis. H(14)CO(-)(3) uptake in the presence of an outward NaCl gradient or inward H(+) gradient, showed no evidence for a Cl(-)- or H(+)- driven HCO(-)(3) transport. H(14)CO(-)(3) and (36)Cl(-) uptakes were stimulated by a positive inside-membrane diffusion potential, suggesting the presence of HCO(-)(3) and Cl(-) conductances. A carbonic anhydrase (CA) activity was measured on plasma membrane (4%) and in the cytoplasm of the ectodermal cells (96%) and was sensitive to acetazolamide (IC(50) = 20 nM) and ethoxyzolamide (IC(50) = 2.5 nM). A strong DIDS-sensitive H(+)-ATPase activity was observed (IC(50) = 14 microM). This activity was also highly sensitive to vanadate and allyl isothiocyanate, two inhibitors of P-type H(+)-ATPases. Present data suggest that HCO(-)(3) absorption by ectodermal cells is carried out by H(+) secretion by H(+)-ATPase, resulting in the formation of carbonic acid in the surrounding seawater, which is quickly dehydrated into CO(2) by a membrane-bound CA. CO(2) then diffuses passively into the cell where it is hydrated in HCO(-)(3) by a cytosolic CA.

Effect of carbon nanotubes upon emissions from cutting and sanding carbon fiber-epoxy composites

Energy Technology Data Exchange (ETDEWEB)

Heitbrink, William A. [LMK OSH Consulting LLC (United States); Lo, Li-Ming, E-mail: LLo@cdc.gov [Centers for Disease Control and Prevention (CDC), Division of Applied Research and Technology, National Institute for Occupational Safety and Health (NIOSH) (United States)

2015-08-15

Carbon nanotubes (CNTs) are being incorporated into structural composites to enhance material strength. During fabrication or repair activities, machining nanocomposites may release CNTs into the workplace air. An experimental study was conducted to evaluate the emissions generated by cutting and sanding on three types of epoxy-composite panels: Panel A containing graphite fibers, Panel B containing graphite fibers and carbon-based mat, and Panel C containing graphite fibers, carbon-based mat, and multi-walled CNTs. Aerosol sampling was conducted with direct-reading instruments, and filter samples were collected for measuring elemental carbon (EC) and fiber concentrations. Our study results showed that cutting Panel C with a band saw did not generate detectable emissions of fibers inspected by transmission electron microscopy but did increase the particle mass, number, and EC emission concentrations by 20–80 % compared to Panels A and B. Sanding operation performed on two Panel C resulted in fiber emission rates of 1.9 × 10{sup 8} and 2.8 × 10{sup 6} fibers per second (f/s), while no free aerosol fibers were detected from sanding Panels A and B containing no CNTs. These free CNT fibers may be a health concern. However, the analysis of particle and EC concentrations from these same samples cannot clearly indicate the presence of CNTs, because extraneous aerosol generation from machining the composite epoxy material increased the mass concentrations of the EC.

Effect of carbon nanotubes upon emissions from cutting and sanding carbon fiber-epoxy composites

International Nuclear Information System (INIS)

Heitbrink, William A.; Lo, Li-Ming

2015-01-01

Carbon nanotubes (CNTs) are being incorporated into structural composites to enhance material strength. During fabrication or repair activities, machining nanocomposites may release CNTs into the workplace air. An experimental study was conducted to evaluate the emissions generated by cutting and sanding on three types of epoxy-composite panels: Panel A containing graphite fibers, Panel B containing graphite fibers and carbon-based mat, and Panel C containing graphite fibers, carbon-based mat, and multi-walled CNTs. Aerosol sampling was conducted with direct-reading instruments, and filter samples were collected for measuring elemental carbon (EC) and fiber concentrations. Our study results showed that cutting Panel C with a band saw did not generate detectable emissions of fibers inspected by transmission electron microscopy but did increase the particle mass, number, and EC emission concentrations by 20–80 % compared to Panels A and B. Sanding operation performed on two Panel C resulted in fiber emission rates of 1.9 × 10 8 and 2.8 × 10 6 fibers per second (f/s), while no free aerosol fibers were detected from sanding Panels A and B containing no CNTs. These free CNT fibers may be a health concern. However, the analysis of particle and EC concentrations from these same samples cannot clearly indicate the presence of CNTs, because extraneous aerosol generation from machining the composite epoxy material increased the mass concentrations of the EC

Deforestation and Carbon Stock Loss in Brazil's Amazonian Settlements.

Science.gov (United States)

Yanai, Aurora Miho; Nogueira, Euler Melo; de Alencastro Graça, Paulo Maurício Lima; Fearnside, Philip Martin

2017-03-01

We estimate deforestation and the carbon stock in 2740 (82 %) of the 3325 settlements in Brazil's Legal Amazonia region. Estimates are made both using available satellite data and a carbon map for the "pre-modern" period (prior to 1970). We used data from Brazil's Project for Monitoring Deforestation in Amazonia updated through 2013 and from the Brazilian Biomes Deforestation Monitoring Project (PMDBBS) updated through 2010. To obtain the pre-modern and recent carbon stocks we performed an intersection between a carbon map and a map derived from settlement boundaries and deforestation data. Although the settlements analyzed occupied only 8 % of Legal Amazonia, our results indicate that these settlements contributed 17 % (160,410 km 2 ) of total clearing (forest + non-forest) in Legal Amazonia (967,003 km 2 ). This represents a clear-cutting of 41 % of the original vegetation in the settlements. Out of this total, 72 % (115,634 km 2 ) was in the "Federal Settlement Project" (PA) category. Deforestation in settlements represents 20 % (2.6 Pg C) of the total carbon loss in Legal Amazonia (13.1 Pg C). The carbon stock in remaining vegetation represents 3.8 Pg C, or 6 % of the total remaining carbon stock in Legal Amazonia (58.6 Pg C) in the periods analyzed. The carbon reductions in settlements are caused both by the settlers and by external actors. Our findings suggest that agrarian reform policies contributed directly to carbon loss. Thus, the implementation of new settlements should consider potential carbon stock losses, especially if settlements are created in areas with high carbon stocks.

Integral Ring Carbon-Carbon Piston

Science.gov (United States)

Northam, G. Burton (Inventor)

1999-01-01

An improved structure for a reciprocating internal combustion engine or compressor piston fabricate from carbon-carbon composite materials is disclosed. An integral ring carbon-carbon composite piston, disclosed herein, reduces the need for piston rings and for small clearances by providing a small flexible, integral component around the piston that allows for variation in clearance due to manufacturing tolerances, distortion due to pressure and thermal loads, and variations in thermal expansion differences between the piston and cylinder liner.

Interaction of carbon nano tubes with DNA segments

International Nuclear Information System (INIS)

Peressinotto, Valdirene Sullas Teixeira

2007-01-01

Single- and double-stranded DNA (deoxyribonucleic acid) molecules can strongly bind to single-walled carbon nanotubes (SWNT) via non-covalent interactions. Under certain conditions, the DNA molecule spontaneously self-assembles into a helical wrapping around the tubular structure of the carbon nanotubes to form DNA/SWNT hybrids, which are both stable and soluble in water. This system has recently received extensive attention, since, besides rendering SWNTs dispersible in water as individual tubes, the DNA hybrids are very promising candidates for many applications in nanotechnology and molecular biology. All the possible applications for DNA-SWNT hybrids require, however, a fully understanding of DNA-nanotube wrapping mechanism which is still lacking in the literature. In this context, the aim of this work was to investigate the non-covalent interaction in aqueous medium between SWNTs and synthetic DNA segments having a known nucleotide sequence. Initially, the study was focused on poly d(GT)n sequences (n = 10, 30 and 45) that contain a sequence of alternating guanine and thymine bases and for which the efficiency to disperse and separate carbon nanotubes has already been demonstrated. Besides the size of GT sequences, the effects of ionic strength and pH in the interaction were also investigated. Afterwards, we studied the interaction of SWNT with DNA molecules that contain only a single type of nitrogenous base (DNA homopolymers), which has not been reported in details in the literature. We investigated homopolymers of poly dA 20 , poly dT 20 , poly dC 20 and the duplex poly dA 20 :dT 20 . Most of the study was carried out with small-diameter HiPco SWNTs (with diameters between 0.7 and 1.2 nm). In some studies, SWNTs with diameter around 1.4 nm, synthesized via laser ablation and arc-discharge methods, were also investigated. The arc-discharge nanotubes used in this study were functionalized with carboxylic groups (-COOH) due to their purification using strong

In Situ Carbon Isotope Analysis by Laser Ablation MC-ICP-MS.

Science.gov (United States)

Chen, Wei; Lu, Jue; Jiang, Shao-Yong; Zhao, Kui-Dong; Duan, Deng-Fei

2017-12-19

Carbon isotopes have been widely used in tracing a wide variety of geological and environmental processes. The carbon isotope composition of bulk rocks and minerals was conventionally analyzed by isotope ratio mass spectrometry (IRMS), and, more recently, secondary ionization mass spectrometry (SIMS) has been widely used to determine carbon isotope composition of carbon-bearing solid materials with good spatial resolution. Here, we present a new method that couples a RESOlution S155 193 nm laser ablation system with a Nu Plasma II MC-ICP-MS, with the aim of measuring carbon isotopes in situ in carbonate minerals (i.e., calcite and aragonite). Under routine operating conditions for δ 13 C analysis, instrumental bias generally drifts by 0.8‰-2.0‰ in a typical analytical session of 2-3 h. Using a magmatic calcite as the standard, the carbon isotopic composition was determined for a suite of calcite samples with δ 13 C values in the range of -6.94‰ to 1.48‰. The obtained δ 13 C data are comparable to IRMS values. The combined standard uncertainty for magmatic calcite is ICP-MS can serve as an appropriate method to analyze carbon isotopes of carbonate minerals in situ.

Aboveground tree growth varies with belowground carbon allocation in a tropical rainforest environment

Science.gov (United States)

J.W. Raich; D.A. Clark; L. Schwendenmann; Tana Wood

2014-01-01

Young secondary forests and plantations in the moist tropics often have rapid rates of biomass accumulation and thus sequester large amounts of carbon. Here, we compare results from mature forest and nearby 15–20 year old tree plantations in lowland Costa Rica to evaluate differences in allocation of carbon to aboveground production and root systems. We found that the...

Triconstituent co-assembly to ordered mesostructured polymer-silica and carbon-silica nanocomposites and large-pore mesoporous carbons with high surface areas.

Science.gov (United States)

Liu, Ruili; Shi, Yifeng; Wan, Ying; Meng, Yan; Zhang, Fuqiang; Gu, Dong; Chen, Zhenxia; Tu, Bo; Zhao, Dongyuan

2006-09-06

Highly ordered mesoporous polymer-silica and carbon-silica nanocomposites with interpenetrating networks have been successfully synthesized by the evaporation-induced triconstituent co-assembly method, wherein soluble resol polymer is used as an organic precursor, prehydrolyzed TEOS is used as an inorganic precursor, and triblock copolymer F127 is used as a template. It is proposed for the first time that ordered mesoporous nanocomposites have "reinforced concrete"-structured frameworks. By adjusting the initial mass ratios of TEOS to resol, we determined the obtained nanocomposites possess continuous composition with the ratios ranging from zero to infinity for the two constituents that are "homogeneously" dispersed inside the pore walls. The presence of silicates in nanocomposites dramatically inhibits framework shrinkage during the calcination, resulting in highly ordered large-pore mesoporous carbon-silica nanocomposites. Combustion in air or etching in HF solution can remove carbon or silica from the carbon-silica nanocomposites and yield ordered mesoporous pure silica or carbon frameworks. The process generates plenty of small pores in carbon or/and silica pore walls. Ordered mesoporous carbons can then be obtained with large pore sizes of approximately 6.7 nm, pore volumes of approximately 2.0 cm(3)/g, and high surface areas of approximately 2470 m(2)/g. The pore structures and textures can be controlled by varying the sizes and polymerization degrees of two constituent precursors. Accordingly, by simply tuning the aging time of TEOS, ordered mesoporous carbons with evident bimodal pores at 2.6 and 5.8 nm can be synthesized.

Particulate inverse opal carbon electrodes for lithium-ion batteries.

Science.gov (United States)

Kang, Da-Young; Kim, Sang-Ok; Chae, Yu Jin; Lee, Joong Kee; Moon, Jun Hyuk

2013-01-29

Inverse opal carbon materials were used as anodes for lithium ion batteries. We applied particulate inverse opal structures and their dispersion in the formation of anode electrodes via solution casting. We prepared aminophenyl-grafted inverse opal carbons (a-IOC), inverse opal carbons with mesopores (mIOC), and bare inverse opal carbons (IOC) and investigated the electrochemical behavior of these samples as anode materials. Surface modification by aminophenyl groups was confirmed by XPS measurements. TEM images showed mesopores, and the specific area of mIOC was compared with that of IOC using BET analysis. A half-cell test was performed to compare a-IOC with IOC and mIOC with IOC. In the case of the a-IOC structure, the cell test revealed no improvement in the reversible specific capacity or the cycle performance. The mIOC cell showed a reversible specific capacity of 432 mAh/g, and the capacity was maintained at 88%-approximately 380 mAh/g-over 20 cycles.

Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocity of marine snow aggregates

Directory of Open Access Journals (Sweden)

M. H. Iversen

2010-09-01

Full Text Available Recent observations have shown that fluxes of ballast minerals (calcium carbonate, opal, and lithogenic material and organic carbon fluxes are closely correlated in the bathypelagic zones of the ocean. Hence it has been hypothesized that incorporation of biogenic minerals within marine aggregates could either protect the organic matter from decomposition and/or increase the sinking velocity via ballasting of the aggregates. Here we present the first combined data on size, sinking velocity, carbon-specific respiration rate, and composition measured directly in three aggregate types; Emiliania huxleyi aggregates (carbonate ballasted, Skeletonema costatum aggregates (opal ballasted, and aggregates made from a mix of both E. huxleyi and S. costatum (carbonate and opal ballasted. Overall average carbon-specific respiration rate was ~0.13 d⁻¹ and did not vary with aggregate type and size. Ballasting from carbonate resulted in 2- to 2.5-fold higher sinking velocities than those of aggregates ballasted by opal. We compiled literature data on carbon-specific respiration rate and sinking velocity measured in aggregates of different composition and sources. Compiled carbon-specific respiration rates (including this study vary between 0.08 d⁻¹ and 0.20 d⁻¹. Sinking velocity increases with increasing aggregate size within homogeneous sources of aggregates. When compared across different particle and aggregate sources, however, sinking velocity appeared to be independent of particle or aggregate size. The carbon-specific respiration rate per meter settled varied between 0.0002 m⁻¹ and 0.0030 m⁻¹, and decreased with increasing aggregate size. It was lower for calcite ballasted aggregates as compared to that of similar sized opal ballasted aggregates.

DYNAMICS OF CARBON SEQUESTRATION IN ABANDONED GRASSLANDS OF NORTHEASTERN MEXICO

Directory of Open Access Journals (Sweden)

José Israel Yerena Yamallel

2014-04-01

Full Text Available Livestock activities due to the improper handling of the load capacity, suffer from low productivity in their grasslands, which are abandoned giving rise to the appearance of species considered invasive and undesirable for producers, without knowing the qualities of these as mitigating of climate change. The objective of the present study was to estimate the carbon content in tamaulipan thornscrub and three abandoned grasslands with a time of abandonment of 10, 20 and 30 years. For the estimation of the carbon content was used a systematic sampling design, in each area were established four sampling sites of 1,600 m2. The primary scrub is the system that resulted in the largest value of carbon content of 14.25 Mg ha-1, followed by the grasslands of 30, 20 and 10 years with 8.03, 7.33 and 4.13 Mg ha-1 respectively. It was concluded that recovering the initial state of the primary scrub take many years, as can be seen in the grasslands system 30 years reaching only 56% of what it had in reserves of primary scrub.

Variability in the carbon storage of seagrass habitats and its implications for global estimates of blue carbon ecosystem service.

Directory of Open Access Journals (Sweden)

Paul S Lavery

Full Text Available The recent focus on carbon trading has intensified interest in 'Blue Carbon'-carbon sequestered by coastal vegetated ecosystems, particularly seagrasses. Most information on seagrass carbon storage is derived from studies of a single species, Posidonia oceanica, from the Mediterranean Sea. We surveyed 17 Australian seagrass habitats to assess the variability in their sedimentary organic carbon (C org stocks. The habitats encompassed 10 species, in mono-specific or mixed meadows, depositional to exposed habitats and temperate to tropical habitats. There was an 18-fold difference in the Corg stock (1.09-20.14 mg C org cm(-3 for a temperate Posidonia sinuosa and a temperate, estuarine P. australis meadow, respectively. Integrated over the top 25 cm of sediment, this equated to an areal stock of 262-4833 g C org m(-2. For some species, there was an effect of water depth on the C org stocks, with greater stocks in deeper sites; no differences were found among sub-tidal and inter-tidal habitats. The estimated carbon storage in Australian seagrass ecosystems, taking into account inter-habitat variability, was 155 Mt. At a 2014-15 fixed carbon price of A$25.40 t(-1 and an estimated market price of $35 t(-1 in 2020, the C org stock in the top 25 cm of seagrass habitats has a potential value of $AUD 3.9-5.4 bill. The estimates of annual C org accumulation by Australian seagrasses ranged from 0.093 to 6.15 Mt, with a most probable estimate of 0.93 Mt y(-1 (10.1 t. km(-2 y(-1. These estimates, while large, were one-third of those that would be calculated if inter-habitat variability in carbon stocks were not taken into account. We conclude that there is an urgent need for more information on the variability in seagrass carbon stock and accumulation rates, and the factors driving this variability, in order to improve global estimates of seagrass Blue Carbon storage.

Distances of Dwarf Carbon Stars

Science.gov (United States)

Harris, Hugh C.; Dahn, Conard C.; Subasavage, John P.; Munn, Jeffrey A.; Canzian, Blaise J.; Levine, Stephen E.; Monet, Alice B.; Pier, Jeffrey R.; Stone, Ronald C.; Tilleman, Trudy M.; Hartkopf, William I.

2018-06-01

Parallaxes are presented for a sample of 20 nearby dwarf carbon stars. The inferred luminosities cover almost two orders of magnitude. Their absolute magnitudes and tangential velocities confirm prior expectations that some originate in the Galactic disk, although more than half of this sample are halo stars. Three stars are found to be astrometric binaries, and orbital elements are determined; their semimajor axes are 1–3 au, consistent with the size of an AGB mass-transfer donor star.

A Nanoporous Carbon/Exfoliated Graphite Composite For Supercapacitor Electrodes

Science.gov (United States)

Rosi, Memoria; Ekaputra, Muhamad P.; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal

2010-12-01

Nanoporous carbon was prepared from coconut shells using a simple heating method. The nanoporous carbon is subjected to different treatments: without activation, activation with polyethylene glycol (PEG), and activation with sodium hydroxide (NaOH)-PEG. The exfoliated graphite was synthesized from graphite powder oxidized with zinc acetate (ZnAc) and intercalated with polyvinyl alcohol (PVA) and NaOH. A composite was made by mixing the nanoporous carbon with NaOH-PEG activation, the exfoliated graphite and a binder of PVA solution, grinding the mixture, and annealing it using ultrasonic bath for 1 hour. All of as-synthesized materials were characterized by employing a scanning electron microscope (SEM), a MATLAB's image processing toolbox, and an x-ray diffractometer (XRD). It was confirmed that the composite is crystalline with (002) and (004) orientations. In addition, it was also found that the composite has a high surface area, a high distribution of pore sizes less than 40 nm, and a high porosity (67%). Noting that the pore sizes less than 20 nm are significant for ionic species storage and those in the range of 20 to 40 nm are very accessible for ionic clusters mobility across the pores, the composite is a promising material for the application as supercapacitor electrodes.

Influences of carbon content and coating carbon thickness on properties of amorphous CoSnO3@C composites as anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Fan, Fuqiang; Fang, Guoqing; Zhang, Ruixue; Xu, Yanhui; Zheng, Junwei; Li, Decheng

2014-01-01

Highlights: • The thickness of carbon coating layers can be successfully controlled through varying molar concentration of aqueous glucose solution. • Coating carbon thickness and carbon content are two important factors on the electrochemical performances of CoSnO3@C. • CoSnO 3 @C under optimized conditions exhibits the optimal balance between the volume buffering effect and reversible capacity. • As-prepared CoSnO 3 @C under optimized conditions shows excellent electrochemical performances, whose reversible capacity could reach 491 mA h g −1 after 100 cycles. - Abstract: A series of core–shell carbon coated amorphous CoSnO 3 (CoSnO 3 @C) with different carbon content are synthesized. Effects of carbon content and coating carbon thickness on the physical and electrochemical performances of the samples were studied in detail. The samples were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), galvanostatic charge–discharge and AC impedance spectroscopy, respectively. The results indicate that controlling the concentration of aqueous glucose solution influences the generation of in-situ carbon layer thickness. The optimal concentration of aqueous glucose solution, carbon content and carbon layer thickness are suggested as 0.25 M, 35.1% and 20 nm, respectively. CoSnO 3 @C composite prepared under the optimal conditions exhibits excellent cycling performance, whose reversible capacity could reach 491 mA h g −1 after 100 cycles

Frictional behavior of carbonate-rich sediments in subduction zones

Science.gov (United States)

Rabinowitz, H. S.; Savage, H. M.; Carpenter, B. M.; Collettini, C.

2016-12-01

Deformation in rocks and sediments is controlled by multiple mechanisms, each governed by its own pressure- (P), temperature- (T), and slip velocity- (v) dependent kinetics. Frictional behavior depends on which of these mechanisms are dominant, and, thus, varies with P, T, and v. Carbonates are a useful material with which to interrogate the PTv controls on friction due to the fact that a wide range of mechanisms can be easily accessed in the lab at geologically relevant conditions. In addition, carbonate-rich layers make up a significant component of subducting sediments around the world and may impact the frictional behavior of shallow subduction zones. In order to investigate the effect of carbonate subduction and the evolution of friction at subduction zone conditions, we conducted deformation experiments on input sediments for two subduction zones, the Hikurangi trench, New Zealand (ODP Site 1124) and the Peru trench (DSDP Site 321), which have carbonate/clay contents of 40/60 wt% and 80/20 wt%, respectively. Samples were saturated with distilled water mixed with 35g/l sea salt and deformed at room temperature. Experiments were conducted at σeff = 1-100 MPa and T = 20-100 °C with sliding velocities of 1-300 μm/s and hold times of 1-1000 s. We test the changes in velocity dependence and healing over these PT conditions to elucidate the frictional behavior of carbonates in subduction zone settings. The mechanical results are complemented by microstructural analysis. In lower stress experiments, there is no obvious shear localization; however, by 25 MPa, pervasive boundary-parallel shears become dominant, particularly in the Peru samples. Optical observations of these shear zones under cross-polarized light show evidence of plastic deformation (CPO development) while SEM-EDS observations indicate phase segregation in the boundary shears. Degree of microstructural localization appears to correspond with the trends observed in velocity-dependence. Our

Effect of heat build-up on carbon emissions in chimato compost piles ...

African Journals Online (AJOL)

A study was conducted to determine impacts of heat build-up of chimato compost piles TD0, TD20, TD40, TD50, TD60, TD80 and TD100, made by blending maize stalks with 0, 20, 40, 50, 60, 80 and 100% Tithonia diversifolia, respectively, on carbon losses and emissions during composting. Compost piles temperatures ...

Soil and biomass carbon re-accumulation after landslide disturbances

Science.gov (United States)

Schomakers, Jasmin; Jien, Shih-Hao; Lee, Tsung-Yu; Huang-Chuan, Jr.; Hseu, Zeng-Yei; Lin, Zan Liang; Lee, Li-Chin; Hein, Thomas; Mentler, Axel; Zehetner, Franz

2017-07-01

In high-standing islands of the Western Pacific, typhoon-triggered landslides occasionally strip parts of the landscape of its vegetative cover and soil layer and export large amounts of biomass and soil organic carbon (OC) from land to the ocean. After such disturbances, new vegetation colonizes the landslide scars and OC starts to re-accumulate. In the subtropical mountains of Taiwan and in other parts of the world, bamboo (Bambusoideae) species may invade at a certain point in the succession of recovering landslide scars. Bamboo has a high potential for carbon sequestration because of its fast growth and dense rooting system. However, it is still largely unknown how these properties translate into soil OC re-accumulation rates after landslide disturbance. In this study, a chronosequence was established on four former landslide scars in the Central Mountain Range of Taiwan, ranging in age from 6 to 41 years post disturbance as determined by landslide mapping from remote sensing. The younger landslide scars were colonized by Miscanthus floridulus, while after approx. 15 to 20 years of succession, bamboo species (Phyllostachys) were dominating. Biomass and soil OC stocks were measured on the recovering landslide scars and compared to an undisturbed Cryptomeria japonica forest stand in the area. After initially slow re-vegetation, biomass carbon accumulated in Miscanthus stands with mean annual accretion rates of 2 ± 0.5 Mg C ha- 1 yr- 1. Biomass carbon continued to increase after bamboo invasion and reached 40% of that in the reference forest site after 41 years of landslide recovery. Soil OC accumulation rates were 2.0 Mg C ha- 1 yr- 1, 6 to 41 years post disturbance reaching 64% of the level in the reference forest. Our results from this in-situ study suggest that recovering landslide scars are strong carbon sinks once an initial lag period of vegetation re-establishment is overcome.

A deeper look at the relationship between root carbon pools and the vertical distribution of the soil carbon pool

Directory of Open Access Journals (Sweden)

R. Dietzel

2017-08-01

Full Text Available Plant root material makes a substantial contribution to the soil organic carbon (C pool, but this contribution is disproportionate below 20 cm where 30 % of root mass and 50 % of soil organic C is found. Root carbon inputs changed drastically when native perennial plant systems were shifted to cultivated annual plant systems. We used the reconstruction of a native prairie and a continuous maize field to examine both the relationship between root carbon and soil carbon and the fundamental rooting system differences between the vegetation under which the soils developed versus the vegetation under which the soils continue to change. In all treatments we found that root C  :  N ratios increased with depth, and this plays a role in why an unexpectedly large proportion of soil organic C is found below 20 cm. Measured root C  :  N ratios and turnover times along with modeled root turnover dynamics showed that in the historical shift from prairie to maize, a large, structural-tissue-dominated root C pool with slow turnover concentrated at shallow depths was replaced by a small, nonstructural-tissue-dominated root C pool with fast turnover evenly distributed in the soil profile. These differences in rooting systems suggest that while prairie roots contribute more C to the soil than maize at shallow depths, maize may contribute more C to soil C stocks than prairies at deeper depths.

High-performance radio frequency transistors based on diameter-separated semiconducting carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Cao, Yu; Che, Yuchi; Zhou, Chongwu, E-mail: chongwuz@usc.edu [Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States); Seo, Jung-Woo T.; Hersam, Mark C. [Department of Materials Science and Engineering and Department of Chemistry, Northwestern University, Evanston, Illinois 60208 (United States); Gui, Hui [Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089 (United States)

2016-06-06

In this paper, we report the high-performance radio-frequency transistors based on the single-walled semiconducting carbon nanotubes with a refined average diameter of ∼1.6 nm. These diameter-separated carbon nanotube transistors show excellent transconductance of 55 μS/μm and desirable drain current saturation with an output resistance of ∼100 KΩ μm. An exceptional radio-frequency performance is also achieved with current gain and power gain cut-off frequencies of 23 GHz and 20 GHz (extrinsic) and 65 GHz and 35 GHz (intrinsic), respectively. These radio-frequency metrics are among the highest reported for the carbon nanotube thin-film transistors. This study provides demonstration of radio frequency transistors based on carbon nanotubes with tailored diameter distributions, which will guide the future application of carbon nanotubes in radio-frequency electronics.

Accumulation of organic carbon in northwestern Arabian sea sediments

International Nuclear Information System (INIS)

Khan, A.A.

1999-01-01

In this study accumulation of organic carbon in marine sediments of northwestern Arabian sea has been discussed. This paper presents the geochemical analysis of Organic carbon content and accumulation, delta 13 stable carbon isotope and Ba/Al. The primary objective was to investigate the high resolution information about the variations in paleoproductivity and source of organic matter in sediments below an upwelling area. Undisturbed sediments (Piston core NIOP-486) of late Pleistocene time were collected during Netherlands Indian Ocean Program (NIOP-1992-93). The core NIOP-486 was raised from a depth of 2077 meters near the Owen Ridge. This core records deposition history of last 200,000 years and includes 4 warm and 3 cold periods. The distribution of organic carbon content in studied core shows a pronounced cyclicity during glacial and interglacial stages. Organic carbon accumulation trends show that high sedimentation rates in glacial stages results in rapid burial and hence increase organic carbon accumulation. Paleoproductivity indicator Ba/Al has been used to compare with the organic carbon content and is correlated with the warm and cold periods variations in monsoons upwelling intensity. Generally, low paleoproductivity is found in glacial stages. The organic carbon content and accumulation, in sediments however seems to differ from the paleoproductivity trends shown by Ba/Al in glacial sediments of stage 6. Delta 13 C.org isotope results of the core NIOP-486 confirm that organic matter in sediments is predominantly marine (-20 to -23% ). (author)

Reducing emissions from deforestation and degradation: What contribution from carbon markets?

OpenAIRE

Bellassen , Valentin; Crassous , R.; Dietzsch , L.; Schwartzman , S.

2008-01-01

Tropical deforestation is responsible for 15-20% of total man-made emissions of greenhouse gases. In December 2007, at the international conference of Bali, the United Nations acknowledged that a viable solution to climate change must include a mechanism to limit deforestation and forest degradation. Today, the most widely used economic tool to reduce emissions is carbon markets: caps on emitters, and trade allowed between emitters and reducers, drive a price signal on carbon and provide ince...

CARBON DIOXIDE CAPTURE FROM FLUE GAS USING DRY REGENERABLE SORBENTS

International Nuclear Information System (INIS)

David A. Green; Brian S. Turk; Raghubir P. Gupta; William J. McMichael; Douglas P. Harrison; Ya Liang

2002-01-01

The objective of this project is to develop a simple, inexpensive process to separate CO(sub 2) as an essentially pure stream from a fossil fuel combustion system using a regenerable, sodium-based sorbent. The sorbent being used in this project is sodium carbonate which is converted to sodium bicarbonate, or ''baking soda,'' through reaction with carbon dioxide and water vapor. Sodium bicarbonate is regenerated to sodium carbonate when heated, producing a nearly pure CO(sub 2) stream after condensation of water vapor. This quarter, five cycle thermogravimetric tests were conducted at the Louisiana State University (LSU) with sodium bicarbonate Grade 3 (SBC(number s ign)3) which showed that carbonation activity declined slightly over 5 cycles following severe calcination conditions of 200 C in pure CO(sub 2). Three different sets of calcination conditions were tested. Initial carbonation activity (as measured by extent of reaction in the first 25 minutes) was greatest subsequent to calcination at 120 C in He, slightly less subsequent to calcination in 80% CO(sub 2)/20% H(sub 2)O, and lowest subsequent to calcination in pure CO(sub 2) at 200 C. Differences in the extent of reaction after 150 minutes of carbonation, subsequent to calcination under the same conditions followed the same trend but were less significant. The differences between fractional carbonation under the three calcination conditions declined with increasing cycles. A preliminary fixed bed reactor test was also conducted at LSU. Following calcination, the sorbent removed approximately 19% of the CO(sub 2) in the simulated flue gas. CO(sub 2) evolved during subsequent calcination was consistent with an extent of carbonation of approximately 49%. Following successful testing of SBC(number s ign)3 sorbent at RTI reported in the last quarter, a two cycle fluidized bed reactor test was conducted with trona as the sorbent precursor, which was calcined to sodium carbonate. In the first carbonation cycle, CO

CARBON DIOXIDE CAPTURE FROM FLUE GAS USING DRY REGENERABLE SORBENTS

Energy Technology Data Exchange (ETDEWEB)

David A. Green; Brian S. Turk; Raghubir P. Gupta; William J. McMichael; Douglas P. Harrison; Ya Liang

2002-01-01

The objective of this project is to develop a simple, inexpensive process to separate CO{sub 2} as an essentially pure stream from a fossil fuel combustion system using a regenerable, sodium-based sorbent. The sorbent being used in this project is sodium carbonate which is converted to sodium bicarbonate, or ''baking soda,'' through reaction with carbon dioxide and water vapor. Sodium bicarbonate is regenerated to sodium carbonate when heated, producing a nearly pure CO{sub 2} stream after condensation of water vapor. This quarter, five cycle thermogravimetric tests were conducted at the Louisiana State University (LSU) with sodium bicarbonate Grade 3 (SBC{number_sign}3) which showed that carbonation activity declined slightly over 5 cycles following severe calcination conditions of 200 C in pure CO{sub 2}. Three different sets of calcination conditions were tested. Initial carbonation activity (as measured by extent of reaction in the first 25 minutes) was greatest subsequent to calcination at 120 C in He, slightly less subsequent to calcination in 80% CO{sub 2}/20% H{sub 2}O, and lowest subsequent to calcination in pure CO{sub 2} at 200 C. Differences in the extent of reaction after 150 minutes of carbonation, subsequent to calcination under the same conditions followed the same trend but were less significant. The differences between fractional carbonation under the three calcination conditions declined with increasing cycles. A preliminary fixed bed reactor test was also conducted at LSU. Following calcination, the sorbent removed approximately 19% of the CO{sub 2} in the simulated flue gas. CO{sub 2} evolved during subsequent calcination was consistent with an extent of carbonation of approximately 49%. Following successful testing of SBC{number_sign}3 sorbent at RTI reported in the last quarter, a two cycle fluidized bed reactor test was conducted with trona as the sorbent precursor, which was calcined to sodium carbonate. In the first

Lithium iron phosphate/carbon nanocomposite film cathodes for high energy lithium ion batteries

International Nuclear Information System (INIS)

Liu, Yanyi; Liu, Dawei; Zhang, Qifeng; Yu, Danmei; Liu, Jun; Cao, Guozhong

2011-01-01

This paper reports sol-gel derived nanostructured LiFePO4/carbon nanocomposite film cathodes exhibiting enhanced electrochemical properties and cyclic stabilities. LiFePO4/carbon films were obtained by spreading sol on Pt coated Si wafer followed by ambient drying overnight and annealing/pyrolysis at elevated temperature in nitrogen. Uniform and crack-free LiFePO4/carbon nanocomposite films were readily obtained and showed olivine phase as determined by means of X-Ray Diffractometry. The electrochemical characterization revealed that, at a current density of 200 mA/g (1.2 C), the nanocomposite film cathodes demonstrated an initial lithium-ion intercalation capacity of 312 mAh/g, and 218 mAh/g after 20 cycles, exceeding the theoretical storage capacity of conventional LiFePO4 electrode. Such enhanced Li-ion intercalation performance could be attributed to the nanocomposite structure with fine crystallite size below 20 nm as well as the poor crystallinity which provides a partially open structure allowing easy mass transport and volume change associated with Li-ion intercalation. Moreover the surface defect introduced by carbon nanocoating could also effectively facilitate the charge transfer and phase transitions.

Preparation of carbon nanotubes from vacuum pyrolysis of polycarbosilane

International Nuclear Information System (INIS)

Jou, S.; Hsu, C.K.

2004-01-01

Carbon nanotubes (CNTs) were synthesized by vacuum pyrolysis of two types of polycarbosilane (PCS) with iron nano-particles between 800 and 1100 deg. C. Straight nanotubes were obtained from low molecular weight (990 g/mol) PCS whereas curled nanotubes were derived from medium molecular weight (1290 g/mol) PCS. Diameters of these straight and curled nanotubes were between 5 and 20 nm. The mechansim of condensed phase growth of carbon nanotubes was discussed. Electron emission capability of these carbon nanotubes increased with their pyrolyzing temperature. The electric fields required to emit a current density of 10 -2 A/cm 2 from the straight nanotubes being pyrolyzed at 800, 900, 1000, and 1100 deg. C were 1.17, 0.73, 0.67, and 0.33 V/μm, respectively

Preparation and characterization of flake graphite/silicon/carbon spherical composite as anode materials for lithium-ion batteries

International Nuclear Information System (INIS)

Lai Jun; Guo Huajun; Wang Zhixing; Li Xinhai; Zhang Xiaoping; Wu Feixiang; Yue Peng

2012-01-01

Highlights: ► Flake graphite/silicon/carbon composite is synthesized via spray drying. ► Flake graphite of ∼0.5 μm and glucose are used to prepare the composite. ► The as-prepared composite shows spherical and porous appearance. ► The composite shows nearly the same cycleability as commercial graphite in 20 cycles. ► The composite shows a reversible capacity of 552 mAh/g at the 20th cycle. - Abstract: Using nano-Si, glucose and flake graphite of ∼0.5 μm as raw materials, flake graphite/silicon/carbon composite is successfully synthesized via spray drying and subsequent pyrolysis. The samples are characterized by XRD, SEM, TEM and electrochemical measurements. The composite is composed of flake graphite, nano-Si and amorphous glucose-pyrolyzed carbon and presents good spherical appearance. Some micron pores arising from the decomposition of glucose exist on the surface of the composite particles. The composite has a high reversible capacity of 602.7 mAh/g with an initial coulombic efficiency of 69.71%, and shows nearly the same cycleability as the commercial graphite in 20 cycles. Both the glucose-pyrolyzed carbon and the micron pores play important roles in improving the cycleability of the composite. The flake graphite/silicon/carbon composite electrode is a potential alternative to graphite for high energy-density lithium ion batteries.

Black carbon radiative forcing at TOA decreased during aging.

Science.gov (United States)

Wu, Yu; Cheng, Tianhai; Zheng, Lijuan; Chen, Hao

2016-12-05

During aging processing, black carbon (also called soot) particles may tend to be mixed with other aerosols, and highly influence their radiative forcing. In this study, freshly emitted soot particles were simulated as fractal aggregates composed of small spherical primary monomers. After aging in the atmosphere, soot monomers were coated by a thinly layer of sulfate as thinly coated soot particles. These soot particles were entirely embedded into large sulfate particle by further aging, and becoming heavily coated soot particles. In clear-sky conditions, black carbon radiative forcing with different aging states were investigated for the bottom and top of atmosphere (BOA and TOA). The simulations showed that black carbon radiative forcing increased at BOA and decreased at TOA after their aging processes. Thinly and heavily coated states increased up to ~12% and ~35% black carbon radiative forcing at BOA, and black carbon radiative forcing at TOA can reach to ~20% and ~100% smaller for thinly and heavily coated states than those of freshly emitted states, respectively. The effect of aging states of black carbon radiative forcing was varied with surface albedo, aerosol optical depth and solar zenith angles. These findings would be helpful for the assessments of climate change.

CARBON-ENHANCED METAL-POOR STARS IN THE INNER AND OUTER HALO COMPONENTS OF THE MILKY WAY

International Nuclear Information System (INIS)

Carollo, Daniela; Norris, John E.; Freeman, Ken C.; Beers, Timothy C.; Lee, Young Sun; Kennedy, Catherine R.; Bovy, Jo; Sivarani, Thirupathi; Aoki, Wako

2012-01-01

Carbon-enhanced metal-poor (CEMP) stars in the halo components of the Milky Way are explored, based on accurate determinations of the carbon-to-iron ([C/Fe]) abundance ratios and kinematic quantities for over 30,000 calibration stars from the Sloan Digital Sky Survey. Using our present criterion that low-metallicity stars exhibiting [C/Fe] ratios ( c arbonicity ) in excess of [C/Fe] =+0.7 are considered CEMP stars, the global frequency of CEMP stars in the halo system for [Fe/H] 5 kpc, the CarDF exhibits a strong tail toward high values, up to [C/Fe] > +3.0. We also find a clear increase in the CEMP frequency with |Z|. For stars with –2.0 < [Fe/H] <–1.5, the frequency grows from 5% at |Z| ∼2 kpc to 10% at |Z| ∼10 kpc. For stars with [Fe/H] <–2.0, the frequency grows from 8% at |Z| ∼2 kpc to 25% at |Z| ∼10 kpc. For stars with –2.0 < [Fe/H] <–1.5, the mean carbonicity is ([C/Fe]) ∼+1.0 for 0 kpc < |Z| < 10 kpc, with little dependence on |Z|; for [Fe/H] <–2.0, ([C/Fe]) ∼+1.5, again roughly independent of |Z|. Based on a statistical separation of the halo components in velocity space, we find evidence for a significant contrast in the frequency of CEMP stars between the inner- and outer-halo components—the outer halo possesses roughly twice the fraction of CEMP stars as the inner halo. The carbonicity distribution also differs between the inner-halo and outer-halo components—the inner halo has a greater portion of stars with modest carbon enhancement ([C/Fe] ∼+0.5]); the outer halo has a greater portion of stars with large enhancements ([C/Fe] ∼+2.0), although considerable overlap still exists. We interpret these results as due to the possible presence of additional astrophysical sources of carbon production associated with outer-halo stars, beyond the asymptotic giant-branch source that may dominate for inner-halo stars, with implications for the progenitors of these populations.

Emissions Inventory Report Summary: Reporting Requirements for the New Mexico Administrative Code, Title 20, Chapter 2, Part 73 (20 NMAC 2.73) for Calendar Year 2001

International Nuclear Information System (INIS)

Margorie Stockton

2003-01-01

Los Alamos National Laboratory is subject to annual emissions-reporting requirements for regulated air contaminants under Title 20 of the New Mexico Administrative Code, Chapter 2, Part 73 (20.2.73 NMAC), Notice of Intent and Emissions Inventory Requirements. The applicability of the requirements is based on the Laboratory's potential to emit 100 tons per year of suspended particulate matter, nitrogen oxides, carbon monoxide, sulfur oxides, or volatile organic compounds. For calendar year 2001, the Technical Area 3 steam plant was the primary source of criteria air pollutants from the Laboratory, while research and development activities were the primary source of volatile organic compounds. Emissions of beryllium and aluminum were reported for activities permitted under 20.2.72 NMAC. Hazardous air pollutant emissions from chemical use for research and development activities were also reported

Lithium storage properties of multiwall carbon nanotubes prepared by CVD

International Nuclear Information System (INIS)

Ahn, J.-O.; Andong National University,; Wang, G.X.; Liu, H.K.; Dou, S.X.

2003-01-01

Full text: Multiwall carbon nanotubes (MWCNTs) were synthesised by chemical vapour deposition (CVD) method using acetylene gas. The XRD pattern of as prepared carbon nanotubes showed that the d 002 value is 3.44 Angstroms. The morphology and microstructure of carbon nanotubes were characterized by HRTEM. Most of carbon nanotubes are entangled together to form bundles or ropes. The diameter of the carbon nanotubes is in the range of 10 ∼ 20 nm. There is a small amount of amorphous carbon particles presented in the sample. However, the yield of carbon nanotubes is more than 95%. Electrochemical properties of carbon nanotubes were characterised via a variety of electrochemical testing techniques. The result of CV test showed that the Li insertion potential is quite low, which is very close to O V versus Li + /Li reference electrode, whereas the potential for Li de-intercalation is in the range of 0.2-0.4 V. There exists a slight voltage hysteresis between Li intercalation and Li de-intercalation, which is similar to the other carbonaceous materials. The intensity of redox peaks of carbon nanotubes decrease with scanning cycle, indicating that the reversible Li insertion capacity gradually decreases. The carbon nanotubes electrode demonstrated a reversible lithium storage capacity of 340 mAh/g with good cyclability at moderate current density. Further improvement of Li storage capacity is possible by opening the end of carbon nanotubes to allow lithium insertion into inner graphene sheet of carbon nanotubes. The kinetic properties of lithium insertion in carbon nanotube electrodes were characterised by a.c. impedance measurements. It was found that the lithium diffusion coefficient d Li decreases with an increase of Li ion concentration in carbon nanotube host

Activated Carbon Textile via Chemistry of Metal Extraction for Supercapacitors.

Science.gov (United States)

Lam, Do Van; Jo, Kyungmin; Kim, Chang-Hyun; Kim, Jae-Hyun; Lee, Hak-Joo; Lee, Seung-Mo

2016-12-27

Carbothermic reduction in the chemistry of metal extraction (MO(s) + C(s) → M(s) + CO(g)) using carbon as a sacrificial agent has been used to smelt metals from diverse oxide ores since ancient times. Here, we paid attention to another aspect of the carbothermic reduction to prepare an activated carbon textile for high-rate-performance supercapacitors. On the basis of thermodynamic reducibility of metal oxides reported by Ellingham, we employed not carbon, but metal oxide as a sacrificial agent in order to prepare an activated carbon textile. We conformally coated ZnO on a bare cotton textile using atomic layer deposition, followed by pyrolysis at high temperature (C(s) + ZnO(s) → C'(s) + Zn(g) + CO(g)). We figured out that it leads to concurrent carbonization and activation in a chemical as well as mechanical way. Particularly, the combined effects of mechanical buckling and fracture that occurred between ZnO and cotton turned out to play an important role in carbonizing and activating the cotton textile, thereby significantly increasing surface area (nearly 10 times) compared with the cotton textile prepared without ZnO. The carbon textiles prepared by carbothermic reduction showed impressive combination properties of high power and energy densities (over 20-fold increase) together with high cyclic stability.

Carbon Capture and Storage: Progress and Next Steps

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-07-01

Two years after the G8 leaders commitment to the broad deployment of carbon capture and storage (CCS) by 2020, significant progress has been made towards commercialisation of CCS technologies. Yet the 2008 Hokkaido G8 recommendation to launch 20 large-scale CCS demonstration projects by 2010 remains a challenge and will require that governments and industry accelerate the pace toward achieving this critical goal. This is one of the main findings of a new report by the International Energy Agency (IEA), the Carbon Sequestration Leadership Forum (CSLF), and the Global CCS Institute, to be presented to G8 leaders at their June Summit in Muskoka, Canada.

Porous carbon as electrode material in direct ethanol fuel cells (DEFCs) synthesized by the direct carbonization of MOF-5

KAUST Repository

Khan, Inayatali

2014-01-12

Porous carbon (PC-900) was prepared by direct carbonization of porous metal-organic framework (MOF)-5 (Zn4O(bdc)3, bdc=1,4-benzenedicarboxylate) at 900 °C. The carbon material was deposited with PtM (M=Fe, Ni, Co, and Cu (20 %) metal loading) nanoparticles using the polyol reduction method, and catalysts PtM/PC-900 were designed for direct ethanol fuel cells (DEFCs). However, herein, we are reporting PtFe/PC-900 catalyst combination which has exhibited superior performance among other options. This catalyst was characterized by powder XRD, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and selected area electron diffraction (SAED) technique. The electrocatalytic capability of the catalyst for ethanol electrooxidation was investigated using cyclic voltammetry and direct ethanol single cell testing. The results were compared with those of PtFe and Pt supported on Vulcan XC72 carbon catalysts (PFe/CX-72 and Pt/XC-72) prepared via the same method. It has been observed that the catalyst PtFe/PC-900 developed in this work showed an outstanding normalized activity per gram of Pt (6.8 mA/g Pt) and superior power density (121 mW/cm2 at 90 °C) compared to commercially available carbon-supported catalysts. © Springer-Verlag Berlin Heidelberg 2014.

Porous carbon as electrode material in direct ethanol fuel cells (DEFCs) synthesized by the direct carbonization of MOF-5

KAUST Repository

Khan, Inayatali; Badshah, Amin; Haider, Naghma; Ullah, Shafiq; Anjum, Dalaver H.; Nadeem, Muhammad Arif

2014-01-01

Porous carbon (PC-900) was prepared by direct carbonization of porous metal-organic framework (MOF)-5 (Zn4O(bdc)3, bdc=1,4-benzenedicarboxylate) at 900 °C. The carbon material was deposited with PtM (M=Fe, Ni, Co, and Cu (20 %) metal loading) nanoparticles using the polyol reduction method, and catalysts PtM/PC-900 were designed for direct ethanol fuel cells (DEFCs). However, herein, we are reporting PtFe/PC-900 catalyst combination which has exhibited superior performance among other options. This catalyst was characterized by powder XRD, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and selected area electron diffraction (SAED) technique. The electrocatalytic capability of the catalyst for ethanol electrooxidation was investigated using cyclic voltammetry and direct ethanol single cell testing. The results were compared with those of PtFe and Pt supported on Vulcan XC72 carbon catalysts (PFe/CX-72 and Pt/XC-72) prepared via the same method. It has been observed that the catalyst PtFe/PC-900 developed in this work showed an outstanding normalized activity per gram of Pt (6.8 mA/g Pt) and superior power density (121 mW/cm2 at 90 °C) compared to commercially available carbon-supported catalysts. © Springer-Verlag Berlin Heidelberg 2014.

Acute wood or coal exposure with carbon monoxide intoxication induces sister chromatid exchange

Energy Technology Data Exchange (ETDEWEB)

Ozturk, S.; Vatansever, S.; Cefle, K.; Palanduz, S.; Guler, K.; Erten, N.; Erk, O.; Karan, M.A.; Tascioglu, C. [University of Istanbul, Istanbul (Turkey). Istanbul Faculty of Medicine

2002-07-01

The object of this study was to investigate the genotoxic effect of acute overexposure to combustion products originating from coal or wood stoves in patients presenting with acute carbon monoxide intoxication. The authors analyzed the frequency of sister chromatid exchange and the carboxyhemoglobin concentration in 20 consecutive patients without a history of smoking or drug use who had been treated in the Emergency Care Unit of Istanbul Medical Faculty due to acute carbon monoxide intoxication. All of these cases were domestic accidents due to dysfunctioning coal or wood stoves. The results were compared with a control group of 20 nonsmoking, nondrug-using healthy individuals matched for age, sex, and absence of other chemical exposure. It was concluded that acute exposure to combustion products of wood or coal is genotoxic to DNA. Potential causes of genotoxicity include known mutagenic compounds present in coal or wood smoke and ash, oxygen radicals formed during combustion, as well as hypoxic and reperfusion injury mechanisms initiated by carbon monoxide intoxication.

Textural characterization and chemistry of activated coal obtained starting from stone of African palm at different conditions of temperature and carbonization time

International Nuclear Information System (INIS)

Diaz, Claudia Marcela; Briceno, Nelson; Baquero, Maria Cristina; Giraldo, Liliana; Moreno, Juan Carlos

2002-01-01

Activated carbons are obtained starting from stone of African palm, by means of chemical activation with k 2 CO 3 and thermal activation with CO 2 . The initial material undergoes different conditions of carbonization temperature 600, 750 and 900 Celsius degrades and different times of carbonization 1.0; 1.5; 2.0 and 2.5 hours, with the objective of observing how these conditions affect the porosity of the material. It is observed a low development of the porosity in the carbons carbonized to 900 Celsius degrade and activated chemically. The acidity and basicity are determined for each one of the activated carbons obtained for titration with solutions 0.05 m of sodium hydroxide and of hydrochloric acid respectively. The samples activated chemically present bigger contents of acid groups, for the experimental conditions of work? Than the samples obtained by thermal activation for the activated carbons thermally activated, the values for acid and basic groups are low-between 0,20 and 0,72 meq g-l

Hierarchical carbon nanostructure design: ultra-long carbon nanofibers decorated with carbon nanotubes

International Nuclear Information System (INIS)

El Mel, A A; Achour, A; Gautron, E; Angleraud, B; Granier, A; Le Brizoual, L; Djouadi, M A; Tessier, P Y; Xu, W; Choi, C H

2011-01-01

Hierarchical carbon nanostructures based on ultra-long carbon nanofibers (CNF) decorated with carbon nanotubes (CNT) have been prepared using plasma processes. The nickel/carbon composite nanofibers, used as a support for the growth of CNT, were deposited on nanopatterned silicon substrate by a hybrid plasma process, combining magnetron sputtering and plasma-enhanced chemical vapor deposition (PECVD). Transmission electron microscopy revealed the presence of spherical nanoparticles randomly dispersed within the carbon nanofibers. The nickel nanoparticles have been used as a catalyst to initiate the growth of CNT by PECVD at 600 deg. C. After the growth of CNT onto the ultra-long CNF, SEM imaging revealed the formation of hierarchical carbon nanostructures which consist of CNF sheathed with CNTs. Furthermore, we demonstrate that reducing the growth temperature of CNT to less than 500 deg. C leads to the formation of carbon nanowalls on the CNF instead of CNT. This simple fabrication method allows an easy preparation of hierarchical carbon nanostructures over a large surface area, as well as a simple manipulation of such material in order to integrate it into nanodevices.

Redox Deposition of Nanoscale Metal Oxides on Carbon for Next-Generation Electrochemical Capacitors

Science.gov (United States)

2013-01-01

conductive carbon supports. Many pro- tocols, including electrodeposition ,17 vapor deposi- tion,18 impregnation/decomposition,19 and solgel chemistry20 have...can be mitigated by dispersing the oxide on high-surface-area carbons (via solgel, impregnation, CVD, or electrodeposition methods), a strategy that...et al. Christopher Chervin is a staff scientist at the NRL, where his research focuses on redesigning cathodes for metalair batteries and exploring

CARBON-TO-OXYGEN RATIOS IN M DWARFS AND SOLAR-TYPE STARS

International Nuclear Information System (INIS)

Nakajima, Tadashi; Sorahana, Satoko

2016-01-01

It has been suggested that high C/O ratios (>0.8) in circumstellar disks lead to the formation of carbon-dominated planets. Based on the expectation that elemental abundances in the stellar photospheres give the initial abundances in the circumstellar disks, the frequency distributions of C/O ratios of solar-type stars have been obtained by several groups. The results of these investigations are mixed. Some find C/O > 0.8 in more than 20% of stars, and C/O > 1.0 in more than 6%. Others find C/O > 0.8 in none of the sample stars. These works on solar-type stars are all differential abundance analyses with respect to the Sun and depend on the adopted C/O ratio in the Sun. Recently, a method of molecular line spectroscopy of M dwarfs, in which carbon and oxygen abundances are derived respectively from CO and H 2 O lines in the K band, has been developed. The resolution of the K- band spectrum is 20,000. Carbon and oxygen abundances of 46 M dwarfs have been obtained by this nondifferential abundance analysis. Carbon-to-oxygen ratios in M dwarfs derived by this method are more robust than those in solar-type stars derived from neutral carbon and oxygen lines in the visible spectra because of the difficulty in the treatment of oxygen lines. We have compared the frequency distribution of C/O distributions in M dwarfs with those of solar-type stars and have found that the low frequency of high-C/O ratios is preferred.

CARBON-TO-OXYGEN RATIOS IN M DWARFS AND SOLAR-TYPE STARS

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Tadashi [Astrobiology Center, 2-21-1, Osawa, Mitaka, Tokyo, 181-8588 (Japan); Sorahana, Satoko, E-mail: tadashi.nakajima@nao.ac.jp, E-mail: sorahana@astron.s.u-tokyo.ac.jp [Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan)

2016-10-20

It has been suggested that high C/O ratios (>0.8) in circumstellar disks lead to the formation of carbon-dominated planets. Based on the expectation that elemental abundances in the stellar photospheres give the initial abundances in the circumstellar disks, the frequency distributions of C/O ratios of solar-type stars have been obtained by several groups. The results of these investigations are mixed. Some find C/O > 0.8 in more than 20% of stars, and C/O > 1.0 in more than 6%. Others find C/O > 0.8 in none of the sample stars. These works on solar-type stars are all differential abundance analyses with respect to the Sun and depend on the adopted C/O ratio in the Sun. Recently, a method of molecular line spectroscopy of M dwarfs, in which carbon and oxygen abundances are derived respectively from CO and H{sub 2}O lines in the K band, has been developed. The resolution of the K- band spectrum is 20,000. Carbon and oxygen abundances of 46 M dwarfs have been obtained by this nondifferential abundance analysis. Carbon-to-oxygen ratios in M dwarfs derived by this method are more robust than those in solar-type stars derived from neutral carbon and oxygen lines in the visible spectra because of the difficulty in the treatment of oxygen lines. We have compared the frequency distribution of C/O distributions in M dwarfs with those of solar-type stars and have found that the low frequency of high-C/O ratios is preferred.

Emission pathways to achieve 2.0°C and 1.5°C climate targets

Science.gov (United States)

Su, Xuanming; Takahashi, Kiyoshi; Fujimori, Shinichiro; Hasegawa, Tomoko; Tanaka, Katsumasa; Kato, Etsushi; Shiogama, Hideo; Masui, Toshihiko; Emori, Seita

2017-06-01

We investigated the feasibilities of 2.0°C and 1.5°C climate targets by considering the abatement potentials of a full suite of greenhouse gases, pollutants, and aerosols. We revised the inter-temporal dynamic optimization model DICE-2013R by introducing three features as follows. First, we applied a new marginal abatement cost curve derived under moderate assumptions regarding future socioeconomic development—the Shared Socioeconomic Pathways 2 (SSP2) scenario. Second, we addressed emission abatement for not only industrial CO2 but also land-use CO2, CH4, N2O, halogenated gases, CO, volatile organic compounds, SOx, NOx, black carbon and organic carbon. Third, we improved the treatment of the non-CO2 components in the climate module based on MAGICC 6.0. We obtained the following findings: (1) It is important to address the individual emissions in an analysis of low stabilization scenarios because abating land-use CO2, non-CO2 and aerosol emissions also contributes to maintaining a low level of radiative forcing and substantially affects the climate costs. (2) The 2.0°C target can be efficiently reached under the assumptions of the SSP2 scenario. (3) The 1.5°C target can be met with early deep cuts under the assumption of a temperature overshoot, and it will triple the carbon price and double the mitigation cost compared with the 2.0°C case.

Monitoring Moisture Damage Propagation in GFRP Composites Using Carbon Nanoparticles

Directory of Open Access Journals (Sweden)

Ahmed Al-Sabagh

2017-03-01

Full Text Available Glass fiber reinforced polymer (GFRP composites are widely used in infrastructure applications including water structures due to their relatively high durability, high strength to weight ratio, and non-corrosiveness. Here we demonstrate the potential use of carbon nanoparticles dispersed during GFRP composite fabrication to reduce water absorption of GFRP and to enable monitoring of moisture damage propagation in GFRP composites. GFRP coupons incorporating 2.0 wt % carbon nanofibers (CNFs and 2.0 wt % multi-wall carbon nanotubes (MWCNTs were fabricated in order to study the effect of moisture damage on mechanical properties of GFRP. Water absorption tests were carried out by immersing the GFRP coupons in a seawater bath at two temperatures for a time period of three months. Effects of water immersion on the mechanical properties and glass transition temperature of GFRP were investigated. Furthermore, moisture damage in GFRP was monitored by measuring the electrical conductivity of the GFRP coupons. It was shown that carbon nanoparticles can provide a means of self-sensing that enables the monitoring of moisture damage in GFRP. Despite the success of the proposed technique, it might not be able to efficiently describe moisture damage propagation in GFRP beyond a specific threshold because of the relatively high electrical conductivity of seawater. Microstructural investigations using Fourier Transform Infrared (FTIR explained the significance of seawater immersion time and temperature on the different levels of moisture damage in GFRP.

Analysis and application of classification methods of complex carbonate reservoirs

Science.gov (United States)

Li, Xiongyan; Qin, Ruibao; Ping, Haitao; Wei, Dan; Liu, Xiaomei

2018-06-01

There are abundant carbonate reservoirs from the Cenozoic to Mesozoic era in the Middle East. Due to variation in sedimentary environment and diagenetic process of carbonate reservoirs, several porosity types coexist in carbonate reservoirs. As a result, because of the complex lithologies and pore types as well as the impact of microfractures, the pore structure is very complicated. Therefore, it is difficult to accurately calculate the reservoir parameters. In order to accurately evaluate carbonate reservoirs, based on the pore structure evaluation of carbonate reservoirs, the classification methods of carbonate reservoirs are analyzed based on capillary pressure curves and flow units. Based on the capillary pressure curves, although the carbonate reservoirs can be classified, the relationship between porosity and permeability after classification is not ideal. On the basis of the flow units, the high-precision functional relationship between porosity and permeability after classification can be established. Therefore, the carbonate reservoirs can be quantitatively evaluated based on the classification of flow units. In the dolomite reservoirs, the average absolute error of calculated permeability decreases from 15.13 to 7.44 mD. Similarly, the average absolute error of calculated permeability of limestone reservoirs is reduced from 20.33 to 7.37 mD. Only by accurately characterizing pore structures and classifying reservoir types, reservoir parameters could be calculated accurately. Therefore, characterizing pore structures and classifying reservoir types are very important to accurate evaluation of complex carbonate reservoirs in the Middle East.

Nitrogen, organic carbon and sulphur cycling in terrestrial ecosystems: linking nitrogen saturation to carbon limitation of soil microbial processes

Czech Academy of Sciences Publication Activity Database

Kopáček, Jiří; Cosby, B. J.; Evans, C. D.; Hruška, J.; Moldan, F.; Oulehle, F.; Šantrůčková, H.; Tahovská, K.; Wright, R. F.

2013-01-01

Roč. 115, 1-3 (2013), s. 33-51 ISSN 0168-2563. [BIOGEOMON : international symposium on ecosystem behavior /7./. Northport, 15.07.2012-20.07.2012] R&D Projects: GA ČR(CZ) GAP504/12/1218 Institutional support: RVO:60077344 Keywords : nitrogen * carbon * sulphur * acidification * forest soil * modelling Subject RIV: DJ - Water Pollution ; Quality Impact factor: 3.730, year: 2013

Accounting for nanometer-thick adventitious carbon contamination in X-ray absorption spectra of carbon-based materials.

Science.gov (United States)

Mangolini, Filippo; McClimon, J Brandon; Rose, Franck; Carpick, Robert W

2014-12-16

Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is a powerful technique for characterizing the composition and bonding state of nanoscale materials and the top few nanometers of bulk and thin film specimens. When coupled with imaging methods like photoemission electron microscopy, it enables chemical imaging of materials with nanometer-scale lateral spatial resolution. However, analysis of NEXAFS spectra is often performed under the assumption of structural and compositional homogeneity within the nanometer-scale depth probed by this technique. This assumption can introduce large errors when analyzing the vast majority of solid surfaces due to the presence of complex surface and near-surface structures such as oxides and contamination layers. An analytical methodology is presented for removing the contribution of these nanoscale overlayers from NEXAFS spectra of two-layered systems to provide a corrected photoabsorption spectrum of the substrate. This method relies on the subtraction of the NEXAFS spectrum of the overlayer adsorbed on a reference surface from the spectrum of the two-layer system under investigation, where the thickness of the overlayer is independently determined by X-ray photoelectron spectroscopy (XPS). This approach is applied to NEXAFS data acquired for one of the most challenging cases: air-exposed hard carbon-based materials with adventitious carbon contamination from ambient exposure. The contribution of the adventitious carbon was removed from the as-acquired spectra of ultrananocrystalline diamond (UNCD) and hydrogenated amorphous carbon (a-C:H) to determine the intrinsic photoabsorption NEXAFS spectra of these materials. The method alters the calculated fraction of sp(2)-hybridized carbon from 5 to 20% and reveals that the adventitious contamination can be described as a layer containing carbon and oxygen ([O]/[C] = 0.11 ± 0.02) with a thickness of 0.6 ± 0.2 nm and a fraction of sp(2)-bonded carbon of 0.19 ± 0.03. This

Sol-gel coatings on carbon/carbon composites

International Nuclear Information System (INIS)

Sim, S.M.; Krabill, R.M.; Dalzell, W.J. Jr.; Chu, P.Y.; Clark, D.E.

1986-01-01

The need for structural materials that can withstand severe environments up to 4000 0 F has promulgated the investigation of sol-gel derived ceramic and composite coatings on carbon/carbon composite materials. Alumina and zirconia sols have been deposited via thermophoresis on carbon/carbon substrates

Investigations into the post-natal development of demethylating enzyme systems by determination of carbon dioxide 14 in the air exhaled by mice after applications of carbon 14 dimethyl amino-antipyrine

International Nuclear Information System (INIS)

Schmidt, H.

1982-01-01

Albino mice were subcutaneously injected with carbon 14 dimethyl aminopyrines, the methyl group of which can be metabolised in the organism into carbon dioxide 14. The following results were obtained: In the carbon dioxide 14 exhalation of neonate, young and adult animals after administration of carbon 14 aminopyrine, distinct differences were noted. The maximum of elimination via the lungs occurs after 20-30 minutes in grown-up mice, in neonates or young animals distinctly later (60-90 min). The carbon dioxide 14 exhalation was also measured after additional subcutaneous application of methrotrexate. In mice aged 8 and 10 days a distinct decrease in carbon dioxide 14 exhalation was found. By contrast, a rise in carbon dioxide 14 exhaled was found in mice aged 2 days. The orientating experiments with folic acid and carbon 14 dimethyl aminopyrine show that leucovorin leads to a distinct increase in carbon dioxide 14 exhalation during the first 30 minutes. As a cause of the different degrees of stimulation respectively inhibition of demethylation, different biochemical ways of formaldehyde formation are pointed out. One of these probably includes the folate-dependent reaction. (orig./MG) [de

Not just graphene: The wonderful world of carbon and related nanomaterials

Energy Technology Data Exchange (ETDEWEB)

Gogotsi, Yury

2015-11-27

Carbon, with its variety of allotropes and forms, is the most versatile material, and virtually any combination of mechanical, optical, electrical, and chemical properties can be achieved with carbon by controlling its structure and surface chemistry. The goal of this article is to help readers appreciate the variety of carbon nanomaterials and to describe some engineering applications of the most important of these. Many different materials are needed to meet a variety of performance requirements, but they can all be built of carbon. Considering the example of supercapacitor electrodes, zero- and one-dimensional nanoparticles, such as carbon onions and nanotubes, respectively, deliver very high power because of fast ion sorption/desorption on their outer surfaces. Two-dimensional (2D) graphene offers higher charge/discharge rates than porous carbons and a high volumetric energy density. Three-dimensional porous activated, carbide-derived, and templated carbon networks, with high surface areas and porosities in the angstrom or nanometer range, can provide high energy densities if the pore size is matched with the electrolyte ion size. Finally, carbon-based nanostructures further expand the range of available nanomaterials: Recently discovered 2D transition-metal carbides (MXenes) have already grown into a family with close to 20 members in about four years and challenge graphene in some applications.

Biofixation of Carbon dioxide by Chlamydomonas sp. in a Tubular Photobioreactor

Directory of Open Access Journals (Sweden)

H Hadiyanto

2012-02-01

Full Text Available The biogas production from anaerobic digestion is a potential fuel for power generators application, if biogas can be upgraded to the same standards as fossil natural gas by CO2, H2S, and other non-combustible component removal. Microalgae Chlamydomonas sp. has potency to biofix the carbon dioxide and can be used as an additional food ingredient. The variations of flow rate and carbon dioxide concentration in the process resulting different value of biomass production and carbon dioxide biofixation. Biomass production at 40% carbon dioxide concentration obtained 5.685 gr/dm3 at 10% carbon dioxide concentration obtained 4.892 gr/dm3. The greatest value of carbon dioxide absorption occurs at a 40% concentration amounting to 12.09%. The rate of growth and productivity of microalgae tend to rise in 10% and 20% (%v carbon dioxide concentration, but began started a constant at 30% and 40% (%v carbon dioxide concentration. Biomass production tends to increase in light conditions while a constant in dark conditions. This study used Chlamydomonas sp. as media culture and performed on bubble column and tubular reactor with 6 litres of culture medium at a temperature of 28oC and atmospheric pressure.

Catalytic oxidation of NO to NO2 on activated carbon

International Nuclear Information System (INIS)

Zhancheng Guo; Yusheng Xie

2001-01-01

Catalytic oxidation of NO to NO 2 over activated carbons PAN-ACF, pitch-ACF and coconut-AC at room temperature (30 o C) were studied to develop a method based on oxidative removal of NO from flue gases. For a dry gas, under the conditions of a gas space flow rate 1500 h -1 in the presence of oxygen of 2-20% in volume concentration, the activated coconut carbon with a surface area 1200 m 2 /g converted about 81-94% of NO with increasing oxygen concentration, the pitch based activated carbon fiber with a surface area 1000 m 2 /g about 44-75%, and the polyacrylonitrile-based activated carbon fiber with a surface area 1810 m 2 /g about 25-68%. The order of activity of the activated carbons was PAN-ACF c P NO P O2 β (F/W), where β is 0.042, 0.16, 0.31 for the coconut-AC, the pitch-ACF and the PAN-ACF respectively, and k c is 0.94 at 30 o C. (author)

Carbon K-edge spectra of carbonate minerals.

Science.gov (United States)

Brandes, Jay A; Wirick, Sue; Jacobsen, Chris

2010-09-01

Carbon K-edge X-ray spectroscopy has been applied to the study of a wide range of organic samples, from polymers and coals to interstellar dust particles. Identification of carbonaceous materials within these samples is accomplished by the pattern of resonances in the 280-320 eV energy region. Carbonate minerals are often encountered in the study of natural samples, and have been identified by a distinctive resonance at 290.3 eV. Here C K-edge and Ca L-edge spectra from a range of carbonate minerals are presented. Although all carbonates exhibit a sharp 290 eV resonance, both the precise position of this resonance and the positions of other resonances vary among minerals. The relative strengths of the different carbonate resonances also vary with crystal orientation to the linearly polarized X-ray beam. Intriguingly, several carbonate minerals also exhibit a strong 288.6 eV resonance, consistent with the position of a carbonyl resonance rather than carbonate. Calcite and aragonite, although indistinguishable spectrally at the C K-edge, exhibited significantly different spectra at the Ca L-edge. The distinctive spectral fingerprints of carbonates provide an identification tool, allowing for the examination of such processes as carbon sequestration in minerals, Mn substitution in marine calcium carbonates (dolomitization) and serpentinization of basalts.

Carbon K-edge Spectra of Carbonate Minerals

Energy Technology Data Exchange (ETDEWEB)

Brandes, J.; Wirick, S; Jacobsen, C

2010-01-01

Carbon K-edge X-ray spectroscopy has been applied to the study of a wide range of organic samples, from polymers and coals to interstellar dust particles. Identification of carbonaceous materials within these samples is accomplished by the pattern of resonances in the 280-320 eV energy region. Carbonate minerals are often encountered in the study of natural samples, and have been identified by a distinctive resonance at 290.3 eV. Here C K-edge and Ca L-edge spectra from a range of carbonate minerals are presented. Although all carbonates exhibit a sharp 290 eV resonance, both the precise position of this resonance and the positions of other resonances vary among minerals. The relative strengths of the different carbonate resonances also vary with crystal orientation to the linearly polarized X-ray beam. Intriguingly, several carbonate minerals also exhibit a strong 288.6 eV resonance, consistent with the position of a carbonyl resonance rather than carbonate. Calcite and aragonite, although indistinguishable spectrally at the C K-edge, exhibited significantly different spectra at the Ca L-edge. The distinctive spectral fingerprints of carbonates provide an identification tool, allowing for the examination of such processes as carbon sequestration in minerals, Mn substitution in marine calcium carbonates (dolomitization) and serpentinization of basalts.

Biomass fuels - effects on the carbon dioxide budget

International Nuclear Information System (INIS)

Eriksson, H.; Hallsby, G.

1992-02-01

It is highly desirable that the effects on the carbon dioxide balance of alternative energy sources are evaluated. Two important alternatives studied in Sweden are the extraction of logging residues left in the forest and willow production on farmland. Considered in isolation, a conversion from stem-wood harvest to whole-tree harvest has a negative effect on the carbon dioxide balance, because the amount of soil organic matter decreases. With the assumption that it takes 20 years for the logging residues to decompose, the net decrease in emissions that would result from the replacement of fossil fuels by logging residues appear moderate after 20 years. However, it will grow significantly as time passes. After 100 years with an annual combustion of logging residues the emissions are 12% of those associated with the production of an equivalent amount of energy through oil combustion. Corresponding values for 300 and 500 years are 4% and 2.5% respectively. In less than 100 years there should be a considerable reduction in the Swedish CO 2 -C emissions even if only every second new logging residue-produced TWH replaces a fossil-fuel-produced TWh. From a long-term perspective, effects on carbon reservoirs in Sweden, caused by conversions to whole-tree harvesting in forestry and to willow production on redundant farmland, can be considered negligible in terms of their influence on the carbon dioxide budget of Sweden. The orders of magnitude of influencing fluxes is exemplified in the following: The annual production of 50 TWh, whereof 40 TWh from logging residues, 8 TWh from willow and 2 TWh from annual crops is estimated to cause a total net decrease of the carbon reservoirs within Sweden corresponding to 32 Tg CO 2 -C, whereas the annual production of 50 TWh from oil combustion should emit 1200 Tg CO 2 -C in 300 years, 2000 Tg CO 2 -C in 500 years and so on. (au). 17 refs., 4 tabs

A study of point defects created by electron irradiation of dilute iron-carbon alloys

International Nuclear Information System (INIS)

Leveque, J.L.

1969-10-01

Resistivity and magnetic after effect (m.a.e.) measurements are used to study the influence of carbon atoms on the annealing process of point defects created by electron irradiation (3 MeV) at low temperature (20 deg. K). The presence of the carbon atoms has a strong influence on the recovery sub-stage I E and stage III. For the former, the carbon impurity traps the freely migrating iron interstitial. For the latter the effect is interpreted as being due to formation during annealing, of a carbon vacancy pair. A pronounced m.a.e. band is attributed to the reorientation of this carbon vacancy complex. All these results are coherent with the interpretation of a low temperature migrating free interstitial. (author) [fr

Historic and projected vehicle use and carbon dioxide emissions

International Nuclear Information System (INIS)

Anon.

1990-01-01

Data are presented in this chapter that show a decline in total carbon dioxide emissions per vehicle of about 20 between 1970 and 1987. However, it is also shown that the fuel economy gains of the 1970s and early 1980s in many countries have begun to erode. In the US, low fuel prices combined with a failure to strengthen fuel efficiency standards have led to recent declines in new-car fuel efficiency. Even if these trends are reversed carbon dioxide in the transport sector will not be reduced if over all motor vehicle use continues along present lines

Experiments with the newly available carbon beams at ISOLDE

CERN Multimedia

Garcia borge, M J; Koester, U H; Koldste, G T

2002-01-01

Recent target-ions-source developments at ISOLDE providing significantly increased yields for carbon isotopes, open up for new and intriguing experiments. We propose to exploit this in two different ways. In particular we wish to do an elastic resonance scattering experiment of $^{9}$C on a proton target to gain information on the particle unbound system $^{10}$N. Furthermore we wish to perform decay experiments of the neutron-rich carbon isotopes, with special focus on $^{17-19}$C but also including a test to see whether the even more neutron-rich isotopes $^{20,22}$C are accessible at ISOLDE.

PM, carbon, and PAH emissions from a diesel generator fuelled with soy-biodiesel blends

International Nuclear Information System (INIS)

Tsai, Jen-Hsiung; Chen, Shui-Jen; Huang, Kuo-Lin; Lin, Yuan-Chung; Lee, Wen-Jhy; Lin, Chih-Chung; Lin, Wen-Yinn

2010-01-01

Biodiesels have received increasing attention as alternative fuels for diesel engines and generators. This study investigates the emissions of particulate matter (PM), total carbon (TC), e.g., organic/elemental carbons, and polycyclic aromatic hydrocarbons (PAHs) from a diesel generator fuelled with soy-biodiesel blends. Among the tested diesel blends (B0, B10 (10 vol% soy-biodiesel), B20, and B50), B20 exhibited the lowest PM emission concentration despite the loads (except the 5 kW case), whereas B10 displayed lower PM emission factors when operating at 0 and 10 kW than the other fuel blends. The emission concentrations or factors of EC, OC, and TC were the lowest when B10 or B20 was used regardless of the loading. Under all tested loads, the average concentrations of total-PAHs emitted from the generator using the B10 and B20 were lower (by 38% and 28%, respectively) than those using pure petroleum diesel fuel (B0), while the emission factors of total-PAHs decreased with an increasing ratio of biodiesel to premium diesel. With an increasing loading, although the brake specific fuel consumption decreased, the energy efficiency increased despite the bio/petroleum diesel ratio. Therefore, soy-biodiesel is promising for use as an alternative fuel for diesel generators to increase energy efficiency and reduce the PM, carbon, and PAH emissions.

Influences of carbon content and coating carbon thickness on properties of amorphous CoSnO{sub 3}@C composites as anode materials for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Fan, Fuqiang [Key Laboratory of Lithium Battery Materials of Jiangsu Province, Institute of chemical power sources, Soochow University, Suzhou 215006 (China); Fang, Guoqing [Key Laboratory of Lithium Battery Materials of Jiangsu Province, Institute of chemical power sources, Soochow University, Suzhou 215006 (China); Changzhou Institute of Energy Storage Materials and Devices, Changzhou 213000 (China); Zhang, Ruixue [Key Laboratory of Lithium Battery Materials of Jiangsu Province, Institute of chemical power sources, Soochow University, Suzhou 215006 (China); Xu, Yanhui; Zheng, Junwei [Key Laboratory of Lithium Battery Materials of Jiangsu Province, Institute of chemical power sources, Soochow University, Suzhou 215006 (China); College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006 (China); Li, Decheng, E-mail: lidecheng@suda.edu.cn [Key Laboratory of Lithium Battery Materials of Jiangsu Province, Institute of chemical power sources, Soochow University, Suzhou 215006 (China); College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006 (China)

2014-08-30

Highlights: • The thickness of carbon coating layers can be successfully controlled through varying molar concentration of aqueous glucose solution. • Coating carbon thickness and carbon content are two important factors on the electrochemical performances of CoSnO3@C. • CoSnO{sub 3}@C under optimized conditions exhibits the optimal balance between the volume buffering effect and reversible capacity. • As-prepared CoSnO{sub 3}@C under optimized conditions shows excellent electrochemical performances, whose reversible capacity could reach 491 mA h g{sup −1} after 100 cycles. - Abstract: A series of core–shell carbon coated amorphous CoSnO{sub 3} (CoSnO{sub 3}@C) with different carbon content are synthesized. Effects of carbon content and coating carbon thickness on the physical and electrochemical performances of the samples were studied in detail. The samples were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), galvanostatic charge–discharge and AC impedance spectroscopy, respectively. The results indicate that controlling the concentration of aqueous glucose solution influences the generation of in-situ carbon layer thickness. The optimal concentration of aqueous glucose solution, carbon content and carbon layer thickness are suggested as 0.25 M, 35.1% and 20 nm, respectively. CoSnO{sub 3}@C composite prepared under the optimal conditions exhibits excellent cycling performance, whose reversible capacity could reach 491 mA h g{sup −1} after 100 cycles.

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

International Nuclear Information System (INIS)

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.

2015-01-01

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 cm 2 ), 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

Preparation and characterization of carbon/SiC nanowire/Na-doped carbonated hydroxyapatite multilayer coating for carbon/carbon composites

International Nuclear Information System (INIS)

Leilei, Zhang; Hejun, Li; Kezhi, Li; Shouyang, Zhang; Qiangang, Fu; Yulei, Zhang; Jinhua, Lu; Wei, Li

2014-01-01

Highlights: • CSH coatings were prepared by combination of magnetron sputter ion plating, CVD and UECD. • Na + and CO 3 2− were developed to co-substitute hydroxyapatite. • SiC nanowires were introduced into Na-doped carbonated hydroxyapatite. • CSH coatings showed excellent cell activity and cell proliferation behavior. - Abstract: A carbon/SiC nanowire/Na-doped carbonated hydroxyapatite multilayer coating (CSH coating) was prepared on carbon/carbon composites using a combination method of magnetron sputter ion plating, chemical vapor deposition and ultrasound-assisted electrochemical deposition procedure. The morphology, microstructure and chemical composition of the coating were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results showed that the CSH coating was consisted of three components: carbon layer, SiC nanowires and Na-doped carbonated hydroxyapatite. The carbon layer provided a dense and uniform surface structure for the growth of SiC nanowires. The SiC nanowires exhibited a porous structure, favoring the infiltration of Na-doped carbonated hydroxyapatite crystals. The Na-doped carbonated hydroxyapatite could infiltrate into the pores of SiC nanowires and finally cover the SiC nanowires entirely with a needle shape. The osteoblast-like MG63 cells were employed to assess the in vitro biocompatibility of the CSH coating. The MG63 cells favorably spread and grew well across the CSH coating surface with plenty of filopods and microvilli, exhibiting excellent cell activity. Moreover, the CSH coating elicited higher cell proliferation as compared to bare carbon/carbon composites. In conclusion, the CSH offers great potential as a coating material for future medical application in hard tissue replacement

Preparation and characterization of carbon/SiC nanowire/Na-doped carbonated hydroxyapatite multilayer coating for carbon/carbon composites

Energy Technology Data Exchange (ETDEWEB)

Leilei, Zhang, E-mail: zhangleilei1121@aliyun.com; Hejun, Li; Kezhi, Li; Shouyang, Zhang; Qiangang, Fu; Yulei, Zhang; Jinhua, Lu; Wei, Li

2014-09-15

Highlights: • CSH coatings were prepared by combination of magnetron sputter ion plating, CVD and UECD. • Na{sup +} and CO{sub 3}{sup 2−} were developed to co-substitute hydroxyapatite. • SiC nanowires were introduced into Na-doped carbonated hydroxyapatite. • CSH coatings showed excellent cell activity and cell proliferation behavior. - Abstract: A carbon/SiC nanowire/Na-doped carbonated hydroxyapatite multilayer coating (CSH coating) was prepared on carbon/carbon composites using a combination method of magnetron sputter ion plating, chemical vapor deposition and ultrasound-assisted electrochemical deposition procedure. The morphology, microstructure and chemical composition of the coating were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results showed that the CSH coating was consisted of three components: carbon layer, SiC nanowires and Na-doped carbonated hydroxyapatite. The carbon layer provided a dense and uniform surface structure for the growth of SiC nanowires. The SiC nanowires exhibited a porous structure, favoring the infiltration of Na-doped carbonated hydroxyapatite crystals. The Na-doped carbonated hydroxyapatite could infiltrate into the pores of SiC nanowires and finally cover the SiC nanowires entirely with a needle shape. The osteoblast-like MG63 cells were employed to assess the in vitro biocompatibility of the CSH coating. The MG63 cells favorably spread and grew well across the CSH coating surface with plenty of filopods and microvilli, exhibiting excellent cell activity. Moreover, the CSH coating elicited higher cell proliferation as compared to bare carbon/carbon composites. In conclusion, the CSH offers great potential as a coating material for future medical application in hard tissue replacement.

Preparation and characterization of activated carbon produced from pomegranate seeds by ZnCl 2 activation

Science.gov (United States)

Uçar, Suat; Erdem, Murat; Tay, Turgay; Karagöz, Selhan

2009-08-01

In this study, pomegranate seeds, a by-product of fruit juice industry, were used as precursor for the preparation of activated carbon by chemical activation with ZnCl 2. The influence of process variables such as the carbonization temperature and the impregnation ratio on textural and chemical-surface properties of the activated carbons was studied. When using the 2.0 impregnation ratio at the carbonization temperature of 600 °C, the specific surface area of the resultant carbon is as high as 978.8 m 2 g -1. The results showed that the surface area and total pore volume of the activated carbons at the lowest impregnation ratio and the carbonization temperature were achieved as high as 709.4 m 2 g -1 and 0.329 cm 3 g -1. The surface area was strongly influenced by the impregnation ratio of activation reagent and the subsequent carbonization temperature.

ORGANIC MATTER LABILE FRACTIONS AND CARBON STOCKS IN A TYPIC QUARTZIPSAMMENT CULTIVATED WITH SUGARCANE HARVESTED WITHOUT BURNING

Directory of Open Access Journals (Sweden)

JOSÉ DE SOUZA OLIVEIRA FILHO

2017-01-01

Full Text Available The permanence of sugarcane straw on the soil surface, in systems without the pre-harvest straw burning practice, directly affects the soil organic matter dynamics. The objective of this work was to evaluate the changes in total organic carbon (TOC, carbon in the light organic matter (CLOM and particulate organic carbon (POC, and their carbon stocks in a typic Quartzipsamment cultivated for nine years with sugarcane crops, which were conducted without the pre-harvest straw burning practice, in Paraipaba, State of Ceará, Brazil. Disturbed and undisturbed soil samples were collected at depths of 0.0-0.025, 0.025-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.30 m, in the sugarcane crop area and in an adjacent native forest area, in order to quantify the TOC, CLOM and POC, as well as the carbon stocks accumulated in the layer 0.0-0.30 m related to these fractions (TOCSt, CLOMSt and POCSt. TOC content changes after nine years of sugarcane crops, conducted without pre-harvest straw burning, were found only in the layers 0.10-0.20 and 0.20-0.30 m. The CLOM varied only in the layer 0.025-0.05 m. The POC content changes were more noticeable than the changes in TOC and CMOL. The CLOM of the sugarcane crop area presented high similarity with TOC, which may affect their quantification in studies related to the soil organic matter dynamics. The sugarcane crop increased the TOCSt, POCSt and CLOMSt in the layer 0.0-0.30 m, compared with the adjacent native forest area.

77 FR 25141 - Corrosion-Resistant Carbon Steel Flat Products From Germany and South Korea: Extension of Time...

Science.gov (United States)

2012-04-27

...-Resistant Carbon Steel Flat Products From Germany and South Korea: Extension of Time Limits for Preliminary...) orders on corrosion-resistant carbon steel flat products (CORE) from Germany and South Korea (Korea... from Germany and South Korea: Adequacy Redetermination Memorandum,'' (April 20, 2012). The preliminary...

Soil carbon fractions and enzyme activities under different vegetation types on the Loess Plateau of China

OpenAIRE

Zhang, Haixin; Zeng, Quanchao; An, Shaoshan; Dong, Yanghong; Darboux, Frédéric

2016-01-01

Vegetation restoration was effective way of protecting soil erosion and water conservation on the Loess Plateau. Carbon fractions and enzyme activities were sensitive parameters for assessment of soil remediation through revegetation. Forest, forest steppe and grassland soils were collected at 0–5 cm and 5–20 cm soil layers in Yanhe watershed, Shaanxi Province. Urease, sucrase, alkaline phosphatase, soil organic carbon (SOC), microbial biomass carbon (MBC), easily ox...

Carbon black vs. black carbon and other airborne materials containing elemental carbon: Physical and chemical distinctions

International Nuclear Information System (INIS)

Long, Christopher M.; Nascarella, Marc A.; Valberg, Peter A.

2013-01-01

Airborne particles containing elemental carbon (EC) are currently at the forefront of scientific and regulatory scrutiny, including black carbon, carbon black, and engineered carbon-based nanomaterials, e.g., carbon nanotubes, fullerenes, and graphene. Scientists and regulators sometimes group these EC-containing particles together, for example, interchangeably using the terms carbon black and black carbon despite one being a manufactured product with well-controlled properties and the other being an undesired, incomplete-combustion byproduct with diverse properties. In this critical review, we synthesize information on the contrasting properties of EC-containing particles in order to highlight significant differences that can affect hazard potential. We demonstrate why carbon black should not be considered a model particle representative of either combustion soots or engineered carbon-based nanomaterials. Overall, scientific studies need to distinguish these highly different EC-containing particles with care and precision so as to forestall unwarranted extrapolation of properties, hazard potential, and study conclusions from one material to another. -- Highlights: •Major classes of elemental carbon-containing particles have distinct properties. •Despite similar names, carbon black should not be confused with black carbon. •Carbon black is distinguished by a high EC content and well-controlled properties. •Black carbon particles are characterized by their heterogenous properties. •Carbon black is not a model particle representative of engineered nanomaterials. -- This review demonstrates the significant physical and chemical distinctions between elemental carbon-containing particles e.g., carbon black, black carbon, and engineered nanomaterials

Evaluation of origins of CH4 carbon emitted from rice paddies

Science.gov (United States)

Watanabe, Akira; Takeda, Takuya; Kimura, Makoto

1999-10-01

Possible carbon sources for CH4 emitted from rice paddies are organic matter applied to the fields, such as rice straw (RS), soil organic matter (SOM), and carbon supplied from rice plants (RP), such as exudates and sloughed tissues. To estimate the contribution of each carbon source to CH4 emission, a pot experiment was conducted using 13C-enriched soil sample and 13C-enriched RS as tracers. The percentage contribution of RP carbon was estimated by subtraction. When RS was applied at a rate corresponding to 6 t ha-1, the percentage contributions of RS, SOM, and RP carbon to CH4 emission throughout the period of rice growth were 42%, 18-21%, and 37-40%, respectively. The values for SOM and RP carbon for the treatment in which RS was not applied were 15-20% and 80-85%, respectively. Seasonal variations in the percentage contribution of soil organic carbon to CH4 emission were small in the range between 13% and 30% for the pots with RS and between 15% and 24% for the pots without RS. In the RS-applied treatment, RS and SOM accounted for almost 100% of the CH4 carbon early in the period of rice growth, while 65-70% of the CH4 emission in the milky stage was derived from RP carbon.

Facile Synthesis of Highly Aligned Multiwalled Carbon Nanotubes from Polymer Precursors

Directory of Open Access Journals (Sweden)

Catherine Y. Han

2009-01-01

Full Text Available We report a facile one-step approach which involves no flammable gas, no catalyst, and no in situ polymerization for the preparation of well-aligned carbon nanotube array. A polymer precursor is placed on top of an anodized aluminum oxide (AAO membrane containing regular nanopore arrays, and slow heating under Ar flow allows the molten polymer to wet the template through adhesive force. The polymer spread into the nanopores of the template to form polymer nanotubes. Upon carbonization the resulting multi-walled carbon nanotubes duplicate the nanopores morphology precisely. The process is demonstrated for 230, 50, and 20 nm pore membranes. The synthesized carbon nanotubes are characterized with scanning/transmission electron microscopies, Raman spectroscopy, and resistive measurements. Convenient functionalization of the nanotubes with this method is demonstrated through premixing CoPt nanoparticles in the polymer precursors.

Facile synthesis of highly aligned multiwalled carbon nanotubes from polymer precursors.

Energy Technology Data Exchange (ETDEWEB)

Han, C. Y.; Xiao, Z.-L.; Wang, H. H.; Lin, X.-M.; Trasobares, S.; Cook, R. E.; Richard J. Daley Coll.; Northern Illinois Univ.; Univ. de Cadiz

2009-01-01

We report a facile one-step approach which involves no flammable gas, no catalyst, and no in situ polymerization for the preparation of well-aligned carbon nanotube array. A polymer precursor is placed on top of an anodized aluminum oxide (AAO) membrane containing regular nanopore arrays, and slow heating under Ar flow allows the molten polymer to wet the template through adhesive force. The polymer spread into the nanopores of the template to form polymer nanotubes. Upon carbonization the resulting multi-walled carbon nanotubes duplicate the nanopores morphology precisely. The process is demonstrated for 230, 50, and 20 nm pore membranes. The synthesized carbon nanotubes are characterized with scanning/transmission electron microscopies, Raman spectroscopy, and resistive measurements. Convenient functionalization of the nanotubes with this method is demonstrated through premixing CoPt nanoparticles in the polymer precursors.

Nanoporous Activated Carbon Derived from Rice Husk for High Performance Supercapacitor

Directory of Open Access Journals (Sweden)

Huaxing Xu

2014-01-01

Full Text Available Nanoporous activated carbon material was produced from the waste rice husks (RHs by precarbonizing RHs and activating with KOH. The morphology, structure, and specific surface area were investigated. The nanoporous carbon has the average pore size of 2.2 nm and high specific area of 2523.4 m2 g−1. The specific capacitance of the nanoporous carbon is calculated to be 250 F g−1 at the current density of 1 A g−1 and remains 80% for 198 F g−1 at the current density of 20 A g−1. The nanoporous carbon electrode exhibits long-term cycle life and could keep stable capacitance till 10,000 cycles. The consistently high specific capacitance, rate capacity, and long-term cycle life ability makes it a potential candidate as electrode material for supercapacitor.

Improved Isotherm Data for Adsorption of Methane on Activated Carbons

KAUST Repository

Loh, Wai Soong; Rahman, Kazi Afzalur; Chakraborty, Anutosh; Saha, Bidyut Baran; Choo, Yoo Sang; Khoo, Boo Cheong; Ng, Kim Choon

2010-01-01

This article presents the adsorption isotherms of methane onto two different types of activated carbons, namely, Maxsorb III and ACF (A-20) at temperatures from (5 to 75) °C and pressures up to 2.5 MPa. The volumetric technique has been employed

The paper of the forests like retainers of carbon, an experience in the south of Mexico

International Nuclear Information System (INIS)

De Jong, Ben H; Soto Pinto, Lorena; Montoya Gomez, Guillermo; Nelson, Kristen; Taylor John; Tipper, Richard

1999-01-01

The forests play an important paper in the global cycle of the carbon. At the moment, the deforestation is responsible for approximately 1.8GtC (gigatons of carbon), 20% of the global annual emissions of carbonic gas caused by the human activity. However, it is calculated that the reforestation could retain from 50 to 150 GtC along next 50 years. Concepts related with the retention of carbon are discussed. The necessity is commented of carrying out the regulation of an international market in retention of carbon with the purpose of being able to maintain acceptable norms in the reforestation projects that are executed under this program

Effect of Thermal Annealing on Carbon in In-situ Phosphorous-Doped Si1-xCx films

International Nuclear Information System (INIS)

Adam, Thomas; Loubet, Nicolas; Reznicek, Alexander; Paruchuri, Vamsi; Sampson, Ron; Sadana, Devendra

2012-01-01

The effect of thermal heat treatment on carbon in in-situ phosphorous-doped silicon-carbon is studied as a function of annealing temperature and type. Films of 0 to 2% carbon were deposited using cyclic chemical vapor deposition at reduced pressures. Secondary ion-mass spectroscopy and high-resolution X-ray diffraction were employed to extract the total and substitutional carbon concentration in samples with phosphorous levels of mid-10 20 cm -3 . It was found that millisecond laser annealing drastically improves substitutionality while high thermal budget treatments (furnace, rapid-thermal, or spike annealing) resulted in an almost complete loss of substitutional carbon, independent of preceding or subsequent laser heat treatments.

Hydrogen storage in single-walled carbon nanotubes: methods and results

International Nuclear Information System (INIS)

Poirier, E.; Chahine, R.; Tessier, A.; Cossement, D.; Lafi, L.; Bose, T.K.

2004-01-01

We present high sensitivity gravimetric and volumetric hydrogen sorption measurement systems adapted for in situ conditioning under high temperature and high vacuum. These systems, which allow for precise measurements on small samples and thorough degassing, are used for sorption measurements on carbon nanostructures. We developed one volumetric system for the pressure range 0-1 bar, and two gravimetric systems for 0-1 bar and 0-100 bars. The use of both gravimetric and volumetric methods allows for the cross-checking of the results. The accuracy of the systems has been determined from hydrogen absorption measurements on palladium. The accuracies of the 0-1 bar volumetric and gravimetric systems are about 10 μg and 20 μg respectively. The accuracy of the 0-100 bars gravimetric system is about 20 μg. Hydrogen sorption measurements on single-walled carbon nanotubes (SWNTs) and metal-incorporated- SWNTs are presented. (author)

Analyzing 20 years of Black Carbon measurements in Germany

Science.gov (United States)

Kutzner, R. D.; Quedenau, J.; Kuik, F.; von Schneidemesser, E.; Schmale, J.

2016-12-01

Black Carbon (BC) is an important short-lived climate-forcing pollutant contributing to global warming through absorption of sunlight. In addition, BC, as a component of particulate matter (PM) exerts adverse health effects. Anthropogenic emission sources of BC include residential heating, transport, and agricultural fires, and the dominant natural emission source is wildfires. Despite the adverse effects of BC, legislation that requires mandatory monitoring of BC concentrations does not currently exist in the European Union (EU). Instead, BC is only indirectly monitored as component of PM10 and PM2.5 (PM with a diameter smaller 10 µm and 2.5 µm, respectively). Before the introduction of mandatory PM10 and PM2.5 monitoring in the EU in 2005 and 2015, respectively, `black smoke' (BS), a surrogate for BC, was a required measurement in Germany from the early 1990s. The annual mean limit value was 14 µg/m3 from 1995 and 8 µg/m³ from 1998. In 2004, many measurements were stopped, with the repeal of the regulations. In most German federal states a limited number BC monitoring stations continued to operate. We present a synthesis of BC data from 213 stations across Germany covering the period between 1994 and 2014. Due to the lack of a standardized method and respective legislation, the data set is very heterogeneous relying on twelve different measurement methods including chemical, optical, and thermal-optical methods. Stations include, among others, urban background, traffic and rural. We highlight results from the year 2009, as it is the year with the largest measurement coverage based on the same measurement method, with 28 stations. Further, we calculated trends in BC concentrations for 13 stations with at least 10 years of data, for median concentrations, as well as 5th percentile (background) and 95th percentile (peak episodes). Preliminary results suggest that concentrations have generally declined, with a larger trend at traffic stations compared to urban

A co-confined carbonization approach to aligned nitrogen-doped mesoporous carbon nanofibers and its application as an adsorbent

Energy Technology Data Exchange (ETDEWEB)

Chen, Aibing [College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Liu, Chao [College of Gemmology and Material Technics, Shijiazhuang University of Economic, Huaian Road 136, Shijiazhuang 050031 (China); Yu, Yifeng; Hu, Yongqi; Lv, Haijun; Zhang, Yue; Shen, Shufeng [College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Zhang, Jian [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

2014-07-15

Highlights: • MCNFs were synthesized by a co-confined carbonization method. • The diameter size of MCNFs with bimodal mesoporous structure can be modulated. • The obtained MCNFs manifest better adsorption capacity for SO{sub 2}, CO{sub 2} and Cd{sup 2+}. - Abstract: Nitrogen-doped carbon nanofibers (MCNFs) with an aligned mesoporous structure were synthesized by a co-confined carbonization method using anodic aluminum oxide (AAO) membrane and tetraethylorthosilicate (TEOS) as co-confined templates and ionic liquids as the precursor. The as-synthesized MCNFs with the diameter of 80–120 nm possessed a bulk nitrogen content of 5.3 wt% and bimodal mesoporous structure. The nitrogen atoms were mostly bound to the graphitic network in two forms, i.e. pyridinic and pyrrolic nitrogen, providing adsorption sites for acidic gases like SO{sub 2} and CO{sub 2}. Cyclic experiments revealed a considerable stability of MCNFs over 20 runs of SO{sub 2} adsorption and 15 runs for CO{sub 2} adsorption. The MCNFs also have a preferable adsorption performance for Cd{sup 2+}.

HTGR fuel rods: carbon-carbon composites designed for high weight and low strength

International Nuclear Information System (INIS)

Bullock, R.E.

1977-01-01

The evolution of the process for fabricating fuel rods for the high-temperature gas-cooled reactor (HTGR) by injection and carbonization of a thermoplastic matrix that bonds close-packed beds of pyrocarbon-coated fuel particles together is reviewed for the fresh-fuel cycle, and a variant process involving a thermosetting matrix that would allow free-standing carbonization of refabricated fuel is discussed. Previous attempts to fabricate such injection-bonded fuel rods from undiluted thermosetting binders filled with powdered graphite were unsuccessful, because of damage to coatings on fuel particles that resulted from strong particle-to-matrix bonding in conjunction with large matrix shrinkage on carbonization and subsequent irradiation. These problems have now been overcome through the use of a diluted thermosetting matrix with a low-char-yield additive (fugitive), which produces a more porous char similar to that from the pitch-based thermoplastic used in fabrication of fresh fuel. A 1-to-1 dilution of resin with fugitive produced the optimum binder for injection and carbonization, where the fired matrix in such rods contained about 20 wt% binder char and 80 wt% powdered graphite. Thermosetting fuel rods diluted with various amounts of fugitive to give binder chars that range from 12 to 48 wt% of the fired matrix have been subjected to irradiation screening tests, and rods with no more than 32 wt% binder char appear to perform about as well under irradiation as do pitch-based rods. However, particle damage does begin to occur in those lightly diluted rods in which the less-stable binder char constitutes more than 32 wt% of the fired matrix. (author)

Reaction velocity of sodium hydration in humid air and sodium carbonation in humid carbon dioxide atmosphere. Fundamental study on sodium carbonate process in FBR bulk sodium coolant disposal technology

International Nuclear Information System (INIS)

Tadokoro, Yutaka; Yoshida, Eiichi

1999-11-01

A sodium carbonate processing method, which changes sodium to sodium carbonate and/or sodium bicarbonate by humid carbon dioxide, has been examined and about to be applied to large test loops dismantling. However, that the basic data regarding the progress of the reaction is insufficient on the other hand, is a present condition. The present report therefore aims at presenting basic data regarding the reaction velocity of sodium hydration in humid air and sodium carbonation in humid carbon dioxide atmosphere, and observing the reaction progress, for the application to large test loops dismantling. The test result is summarized as follows. (1) Although the reaction velocity of sodium varied with sodium specimen sizes and velocity measurement methods, the reaction velocity of sodium hydration was in about 0.16 ∼ 0.34 mmh -1 (0.016 ∼ 0.033g cm -2 h -1 , 6.8x10 -4 ∼ 1.4x10 -3 mol cm -2 h -1 ) and that of sodium carbonation was in about 0.16 ∼ 0.27mmh -1 (0.016 ∼ 0.023g cm -2 h -1 , 6.8x10 -4 ∼ 1.1x10 -3 mol cm -2 h -1 ) (26 ∼ 31degC, RH 100%). (2) The reaction velocity of sodium in carbon dioxide atmosphere was greatly affected by vapor partial pressure (absolutely humidity). And the velocity was estimated in 0.08 ∼ 0.12mmh -1 (0.008 ∼ 0.012g cm -2 h -1 , 3.4x10 -4 ∼ 5.2x10 -4 mol cm -2 h -1 ) in the carbon dioxide atmosphere, whose temperature of 20degC and relative humidity of 80% are assumed real sodium carbonate process condition. (3) By the X-ray diffraction method, NaOH was found in humid air reaction product. Na 2 CO 3 , NaHCO 3 were found in carbon dioxide atmosphere reaction product. It was considered that Sodium changes to NaOH, and subsequently to NaHCO 3 through Na 2 CO 3 . (4) For the application to large test loops dismantling, it is considered possible to change sodium to a target amount of sodium carbonate (or sodium bicarbonate) by setting up gas supply quantity and also processing time appropriately according to the surface area

Carbon/carbon composite materials

International Nuclear Information System (INIS)

Thebault, J.; Orly, P.

2006-01-01

Carbon/carbon composites are singular materials from their components, their manufacturing process as well as their characteristics. This paper gives a global overview of these particularities and applications which make them now daily used composites. (authors)

[Effect of straw-returning on the storage and distribution of different active fractions of soil organic carbon].

Science.gov (United States)

Wang, Hul; Wang, Xu-dong; Tian, Xiao-hong

2014-12-01

The impacts of straw mulching and returning on the storage of soil dissolved organic carbon (DOC), particulate organic carbon (POC) and mineral associated organic carbon (MOC), and their proportions to the total organic carbon (TOC) were studied based on a field experiment. The results showed that compared to the treatment of wheat straw soil-returning (WR), the storage of TOC and MOC decreased by 4.1% and 9.7% respectively in 0-20 cm soil in the treatment with wheat straw mulching (WM), but the storage of DOC and POC increased by 207.7% and 11.9%, and TOC and POC increased significantly in 20-40 cm soil. Compared to the treatment with maize straw soil-returning (MR), the storage of TOC and MOC in the plough pan soil of the treatment with maize straw mulching (MM) increased by 13.6% and 14.6% , respectively. Compared to the WR-MR treatment, the storage of TOC and MOC in top soil (0-20 icm) significantly decreased by 8.5% and 10.3% respectively in WM-MM treatment. The storage of TOC, and POC in top soil was significantly higher in the treatments with maize straw soil-returning or mulching than that with wheat straw. Compared to the treatment without straw (CK), the storage of TOC in top soil increased by 5.2% to 18.0% in the treatments with straw returning or mulching in the six modes (WM, WR, MM, MR, WM-MM,WR-MR) (Porganic carbon fraction in soil, straw soil-returning had the potential to accumulate stable organic carbon fraction. Considering organic carbon sequestration in cropland in the region of Guanzhong plain, maize straw mulching or soil-returning was better than wheat straw, and wheat straw and maize straw soil-returning (WR-MR) were better than wheat and maize straw mulching (WM-MM).

Interconnected carbon nanosheets derived from hemp for ultrafast supercapacitors with high energy.

Science.gov (United States)

Wang, Huanlei; Xu, Zhanwei; Kohandehghan, Alireza; Li, Zhi; Cui, Kai; Tan, Xuehai; Stephenson, Tyler James; King'ondu, Cecil K; Holt, Chris M B; Olsen, Brian C; Tak, Jin Kwon; Harfield, Don; Anyia, Anthony O; Mitlin, David

2013-06-25

We created unique interconnected partially graphitic carbon nanosheets (10-30 nm in thickness) with high specific surface area (up to 2287 m(2) g(-1)), significant volume fraction of mesoporosity (up to 58%), and good electrical conductivity (211-226 S m(-1)) from hemp bast fiber. The nanosheets are ideally suited for low (down to 0 °C) through high (100 °C) temperature ionic-liquid-based supercapacitor applications: At 0 °C and a current density of 10 A g(-1), the electrode maintains a remarkable capacitance of 106 F g(-1). At 20, 60, and 100 °C and an extreme current density of 100 A g(-1), there is excellent capacitance retention (72-92%) with the specific capacitances being 113, 144, and 142 F g(-1), respectively. These characteristics favorably place the materials on a Ragone chart providing among the best power-energy characteristics (on an active mass normalized basis) ever reported for an electrochemical capacitor: At a very high power density of 20 kW kg(-1) and 20, 60, and 100 °C, the energy densities are 19, 34, and 40 Wh kg(-1), respectively. Moreover the assembled supercapacitor device yields a maximum energy density of 12 Wh kg(-1), which is higher than that of commercially available supercapacitors. By taking advantage of the complex multilayered structure of a hemp bast fiber precursor, such exquisite carbons were able to be achieved by simple hydrothermal carbonization combined with activation. This novel precursor-synthesis route presents a great potential for facile large-scale production of high-performance carbons for a variety of diverse applications including energy storage.

Synthesis of carbon nanorods by reduction of carbon bisulfide

International Nuclear Information System (INIS)

Lou Zhengsong; He Minglong; Zhao Dejian; Li Zhongchun; Shang Tongming

2010-01-01

Research highlights: Our manuscript is a concise preliminary account of original and of significant research, which illuminates carbon nanorods and variously shaped Y-junction carbon nanorods are successfully fabricated on a large scale through a carbon bisulfide thermal reduction process. Various shaped Y-junction carbon nanorods can be used as studying the electronic and transport properties of the nano-meter carbon material. - Abstract: Carbon nanorods are synthesized at large scale by the reduction of carbon bisulfide at 600 o C. Moreover, novel Y-junction carbon nanorods are detected in the samples. The X-ray power diffraction pattern indicates that the products are hexagonal graphite. Scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and N 2 physisorption studies show that carbon nanorods predominate in the product. Based on the supercritical carbon bisulfide system, the possible growth mechanism of the carbon nanorods was discussed. This method provides a simple and cheap route to large-scale synthesis of carbon nanorods.

Converting Corncob to Activated Porous Carbon for Supercapacitor Application

Directory of Open Access Journals (Sweden)

Shaoran Yang

2018-03-01

Full Text Available Carbon materials derived from biomass are promising electrode materials for supercapacitor application due to their specific porosity, low cost and electrochemical stability. Herein, a hierarchical porous carbon derived from corncob was developed for use as electrodes. Benefitting from its hierarchical porosity, inherited from the natural structure of corncob, high BET surface area (1471.4 m2·g−1 and excellent electrical conductivity, the novel carbon material exhibited a specific capacitance of 293 F·g−1 at 1 A·g−1 in 6 M KOH electrolyte and maintained at 195 F·g−1 at 5 A·g−1. In addition, a two-electrode device was assembled and delivered an energy density of 20.15 Wh·kg−1 at a power density of 500 W·kg−1 and an outstanding stability of 99.9% capacitance retention after 4000 cycles.

Climate constraints on the carbon intensity of economic growth

International Nuclear Information System (INIS)

Rozenberg, Julie; Narloch, Ulf; Hallegatte, Stephane; Davis, Steven J

2015-01-01

Development and climate goals together constrain the carbon intensity of production. Using a simple and transparent model that represents committed CO 2 emissions (future emissions expected to come from existing capital), we explore the carbon intensity of production related to new capital required for different temperature targets across several thousand scenarios. Future pathways consistent with the 2 °C target which allow for continued gross domestic product growth require early action to reduce carbon intensity of new production, and either (i) a short lifetime of energy and industry capital (e.g. early retrofit of coal power plants), or (ii) large negative emissions after 2050 (i.e. rapid development and dissemination of carbon capture and sequestration). To achieve the 2 °C target, half of the scenarios indicate a carbon intensity of new production between 33 and 73 g CO 2 /$—much lower than the global average today, at 360 g CO 2 /$. The average lifespan of energy capital (especially power plants), and industry capital, are critical because they commit emissions far into the future and reduce the budget for new capital emissions. Each year of lifetime added to existing, carbon intensive capital, decreases the carbon intensity of new production required to meet a 2 °C carbon budget by 1.0–1.5 g CO 2 /$, and each year of delaying the start of mitigation decreases the required CO 2 intensity of new production by 20–50 g CO 2 /$. Constraints on the carbon intensity of new production under a 3 °C target are considerably relaxed relative to the 2 °C target, but remain daunting in comparison to the carbon intensity of the global economy today. (letter)

Concentration of enteric virus indicator from seawater using granular activated carbon.

Science.gov (United States)

Cormier, Jiemin; Gutierrez, Miguel; Goodridge, Lawrence; Janes, Marlene

2014-02-01

Fecal contamination of shellfish growing seawater with enteric viruses is often associated with human outbreaks of gastroenteritis. Male specific bacteriophage MS2 is correlated with those of enteric viruses in a wide range of water environments and has been used widely as a surrogate for pathogenic waterborne viruses. Since viruses in contaminated water are usually at low levels, the development of methods to concentrate viruses from water is crucial for detection purposes. In the present study, granular activated carbon was evaluated for concentration of MS2 from artificial seawater, and different parameters of the seawater were also compared. Recovery of MS2 from warm seawater (37°C) was found to be significantly greater than from cold seawater (4 and 20°C), and even greater than from fresh water (4, 20 and 37°C); the difference between seawater and fresh water became less profound when the temperatures of both were below 37°C. Although not of statistical significance, recovery of MS2 from low salinity seawater (10 and 20 parts per thousand, ppt) was greater than from high salinity seawater (30 and 40ppt). One gram of granular activated carbon was able to extract 6-log plaque forming units (PFU) of MS2 from 500ml seawater at 37°C. This study demonstrated that granular activated carbon can concentrate an enteric virus indicator from shellfish growing seawater effectively. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of the origin of dissolved inorganic carbon in groundwater around a reclaimed landfill in Otwock using stable carbon isotopes.

Science.gov (United States)

Porowska, Dorota

2015-05-01

Chemical and isotopic analyses of groundwater from piezometers located around a reclaimed landfill in Otwock (Poland) were performed in order to trace the origin of dissolved inorganic carbon (DIC) in the groundwater. Due to differences in the isotopic composition of carbon from different sources, an analysis of stable carbon isotopes in the groundwater, together with the Keeling plot approach and a two-component mixing model allow us to evaluate the relative contributions of carbon from these sources in the groundwater. In the natural (background) groundwater, DIC concentrations and the isotopic composition of DIC (δ(13)CDIC) comes from two sources: decomposition of organic matter and carbonate dissolution within the aquifer sediments, whereas in the leachate-contaminated groundwater, DIC concentrations and δ(13)CDIC values depend on the degradation of organic matter within the aquifer sediments and biodegradation of organic matter stored in the landfill. From the mixing model, about 4-54% of the DIC pool is derived from organic matter degradation and 96-46% from carbonate dissolution in natural conditions. In the leachate-contaminated groundwater, about 20-53% of the DIC is derived from organic matter degradation of natural origin and 80-47% from biodegradation of organic matter stored in the landfill. Partial pressure of CO2 (P CO2) was generally above the atmospheric, hence atmospheric CO2 as a source of carbon in DIC pool was negligible in the aquifer. P CO2 values in the aquifer in Otwock were always one to two orders of magnitude above the atmospheric P CO2, and thus CO2 escaped directly into the vadose zone. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation of activated Carbons from extracted waste biomass by chemical activation

International Nuclear Information System (INIS)

Toteva, V.; Nickolov, R.

2013-01-01

Full text: Novel biomass precursors for the production of activated carbons (ACs) were studied. ACs were prepared from extracted coffee husks and extracted spent ground coffee - separately or as mixtures with 10, 20 and 30 mass % Bulgarian lignite coal. Activation by potassium hydroxide was employed for all samples. The results obtained show that the surface and porous parameters of the ACs depend on the nature of the initial materials used. The specific surface areas (BET) and the microporosities of ACs obtained from extracted spent ground coffee mixed with 20 mass % Bulgarian lignite coals, are greater than those of the ACs from extracted coffee husks. It is likely that the reason for this result is the chemical composition of the precursors. The coffee husks have less lignin and more holocellulose. The latter undergoes more significant destructive changes in the process of chemical activation. On the contrary, waste ground coffee precursors contain more lignin and less holocellulose. As a result, after the chemical activation, the carbons prepared from extracted spent ground coffee exhibit better porous parameters and higher specific surface areas. key words: activated carbons, extraction, waste biomass

Bird specimens track 135 years of atmospheric black carbon and environmental policy

Science.gov (United States)

DuBay, Shane G.; Fuldner, Carl C.

2017-10-01

Atmospheric black carbon has long been recognized as a public health and environmental concern. More recently, black carbon has been identified as a major, ongoing contributor to anthropogenic climate change, thus making historical emission inventories of black carbon an essential tool for assessing past climate sensitivity and modeling future climate scenarios. Current estimates of black carbon emissions for the early industrial era have high uncertainty, however, because direct environmental sampling is sparse before the mid-1950s. Using photometric reflectance data of >1,300 bird specimens drawn from natural history collections, we track relative ambient concentrations of atmospheric black carbon between 1880 and 2015 within the US Manufacturing Belt, a region historically reliant on coal and dense with industry. Our data show that black carbon levels within the region peaked during the first decade of the 20th century. Following this peak, black carbon levels were positively correlated with coal consumption through midcentury, after which they decoupled, with black carbon concentrations declining as consumption continued to rise. The precipitous drop in atmospheric black carbon at midcentury reflects policies promoting burning efficiency and fuel transitions rather than regulating emissions alone. Our findings suggest that current emission inventories based on predictive modeling underestimate levels of atmospheric black carbon for the early industrial era, suggesting that the contribution of black carbon to past climate forcing may also be underestimated. These findings build toward a spatially dynamic emission inventory of black carbon based on direct environmental sampling.

Carbon dioxide capture from exhaust gases by selective adsorption on porous solids

Energy Technology Data Exchange (ETDEWEB)

Schindler, M.; Ernst, S. [Technische Univ. Kaiserslautern (Germany). Dept. of Chemistry

2007-07-01

The metal-organic frameworks Cu{sub 3}(BTC){sub 2}, MIL-53 and MIL-96 were synthesized and characterized by powder X-ray diffraction, scanning electron microscopy and nitrogenphysisorption. The adsorption isotherms for carbon dioxide at temperatures of 20, 40 and 60 C and pressures up to 1000 mbar on this new type of microporous solids were measured by a static volumetric method. For comparison, experiments with zeolite NaX (13X) were also included. High adsorption capacities for carbon dioxide were found for the adsorbents investigated in this study. The breakthrough curves for the adsorption of a mixture of nitrogen and carbon dioxide on Cu{sub 3}(BTC){sub 2} reveal a high affinity of this material for the adsorption of carbon dioxide in the presence of nitrogen. (orig.)

Carbon dioxide sequestration by mineral carbonation

NARCIS (Netherlands)

Huijgen, W.J.J.

2007-01-01

The increasing atmospheric carbon dioxide (CO2) concentration, mainly caused by fossil fuel combustion, has lead to concerns about global warming. A possible technology that can contribute to the reduction of carbon dioxide emissions is CO2 sequestration by mineral carbonation. The basic concept

Nano-scaled iron-carbon precipitates in HSLC and HSLA steels

Institute of Scientific and Technical Information of China (English)

2007-01-01

This paper studies the composition, quantity and particle size distribution of nano-scaled precipitates with size less than 20 nm in high strength low carbon (HSLC) steel and their effects on mechanical properties of HSLC steel by means of mass balance calculation of nano-scaled precipitates measured by chemical phase analysis plus SAXS method, high-resolution TEM analysis and thermodynamics calculation, as well as temper rapid cooling treatment of ZJ330. It is found that there existed a large quantity of nano-scaled iron-carbon precipitates with size less than 18 nm in low carbon steel produced by CSP and they are mainly Fe-O-C and Fe-Ti-O-C precipitates formed below temperature A1. These precipitates have ob- vious precipitation strengthening effect on HSLC steel and this may be regarded as one of the main reasons why HSLC steel has higher strength. There also existed a lot of iron-carbon precipitates with size less than 36 nm in HSLA steels.

Nano-scaled iron-carbon precipitates in HSLC and HSLA steels

Institute of Scientific and Technical Information of China (English)

FU Jie; WU HuaJie; LIU YangChun; KANG YongLin

2007-01-01

This paper studies the composition, quantity and particle size distribution of nano-scaled precipitates with size less than 20 nm in high strength Iow carbon (HSLC) steel and their effects on mechanical properties of HSLC steel by means of mass balance calculation of nano-scaled precipitates measured by chemical phase analysis plus SAXS method, high-resolution TEM analysis and thermodynamics calculation, as well as temper rapid cooling treatment of ZJ330. It is found that there existed a large quantity of nano-scaled iron-carbon precipitates with size less than 18 nm in Iow carbon steel produced by CSP and they are mainly Fe-O-C and Fe-Ti-O-C precipitates formed below temperature A1. These precipitates have obvious precipitation strengthening effect on HSLC steel and this may be regarded as one of the main reasons why HSLC steel has higher strength. There also existed a lot of iron-carbon precipitates with size less than 36 nm in HSLA steels.

The Earth System Science Pathfinder Orbiting Carbon Observatory (OCO) Mission

Science.gov (United States)

Crisp, David

2003-01-01

A viewgraph presentation describing the Earth System Science Pathfinder Orbiting Carbon Observatory (OCO) Mission is shown. The contents include: 1) Why CO2?; 2) What Processes Control CO2 Sinks?; 3) OCO Science Team; 4) Space-Based Measurements of CO2; 5) Driving Requirement: Precise, Bias-Free Global Measurements; 6) Making Precise CO2 Measurements from Space; 7) OCO Spatial Sampling Strategy; 8) OCO Observing Modes; 9) Implementation Approach; 10) The OCO Instrument; 11) The OCO Spacecraft; 12) OCO Will Fly in the A-Train; 13) Validation Program Ensures Accuracy and Minimizes Spatially Coherent Biases; 14) Can OCO Provide the Required Precision?; 15) O2 Column Retrievals with Ground-based FTS; 16) X(sub CO2) Retrieval Simulations; 17) Impact of Albedo and Aerosol Uncertainty on X(sub CO2) Retrievals; 18) Carbon Cycle Modeling Studies: Seasonal Cycle; 19) Carbon Cycle Modeling Studies: The North-South Gradient in CO2; 20) Carbon Cycle Modeling Studies: Effect of Diurnal Biases; 21) Project Status and Schedule; and 22) Summary.

Carbon Micronymphaea: Graphene on Vertically Aligned Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Jong Won Choi

2013-01-01

Full Text Available This paper describes the morphology of carbon nanomaterials such as carbon nanotube (CNT, graphene, and their hybrid structure under various operating conditions during a one-step synthesis via plasma-enhanced chemical vapor deposition (PECVD. We focus on the synthetic aspects of carbon hybrid material composed of heteroepitaxially grown graphene on top of a vertical array of carbon nanotubes, called carbon micronymphaea. We characterize the structural features of this unique nanocomposite by uses of electron microscopy and micro-Raman spectroscopy. We observe carbon nanofibers, poorly aligned and well-aligned vertical arrays of CNT sequentially as the growth temperature increases, while we always discover the carbon hybrids, called carbon micronymphaea, at specific cooling rate of 15°C/s, which is optimal for the carbon precipitation from the Ni nanoparticles in this study. We expect one-pot synthesized graphene-on-nanotube hybrid structure poses great potential for applications that demand ultrahigh surface-to-volume ratios with intact graphitic nature and directional electronic and thermal transports.

Bonding Characteristics of Macrosynthetic Fiber in Latex-Modified Fiber-Reinforced Cement Composites as a Function of Carbon Nanotube Content

Directory of Open Access Journals (Sweden)

Ji-Hong Jean

2016-01-01

Full Text Available The effect of carbon nanotube content (0, 0.5, 1.0, 1.5, and 2.0% of the cement weight on the bonding properties of macrosynthetic fiber in latex-modified hybrid fiber cement-based composites (LMHFRCCs was evaluated. The slump value, compressive strength, and bonding strength were measured for each LMHFRCC. As the carbon nanotube content increased to 1.5%, the bonding properties of the macrosynthetic fiber improved. However, the bonding performance deteriorated at a carbon nanotube content of 2.0%. A decrease in the fluidity of the mix negatively affected the dispersion of the nanotubes in the LMHFRCCs. The addition of carbon nanotubes also affected the relative bonding strength independently of the improvement in compressive strength. Microscopic analysis of the macrosynthetic fiber surfaces was used to understand changes in the bonding behavior.

Preparation of Carbon-Platinum-Ceria and Carbon-Platinum-Cerium catalysts and its application in Polymer Electrolyte Fuel Cell: Hydrogen, Methanol, and Ethanol

Science.gov (United States)

Guzman Blas, Rolando Pedro

This thesis is focused on fuel cells using hydrogen, methanol and ethanol as fuel. Also, in the method of preparation of catalytic material for the anode: Supercritical Fluid Deposition (SFD) and impregnation method using ethylenediaminetetraacetic acid (EDTA) as a chelating agent. The first part of the thesis describes the general knowledge about Hydrogen Polymer Exchange Membrane Fuel Cell (HPEMFC),Direct Methanol Fuel Cell (DMFC) and Direct Ethanol Fuel Cell (DEFC), as well as the properties of Cerium and CeO2 (Ceria). The second part of the thesis describes the preparation of catalytic material by Supercritical Fluid Deposition (SFD). SFD was utilized to deposit Pt and ceria simultaneously onto gas diffusion layers. The Pt-ceria catalyst deposited by SFD exhibited higher methanol oxidation activity compared to the platinum catalyst alone. The linear sweep traces of the cathode made for the methanol cross over study indicate that Pt-Ceria/C as the anode catalyst, due to its better activity for methanol, improves the fuel utilization, minimizing the methanol permeation from anode to cathode compartment. The third and fourth parts of the thesis describe the preparation of material catalytic material Carbon-Platinum-Cerium by a simple and cheap impregnation method using EDTA as a chelating agent to form a complex with cerium (III). This preparation method allows the mass production of the material catalysts without additional significant cost. Fuel cell polarization and power curves experiments showed that the Carbon-Platinum-Cerium anode materials exhibited better catalytic activity than the only Vulcan-Pt catalysts for DMFC, DEFC and HPEMFC. In the case of Vulcan-20%Pt-5%w Cerium, this material exhibits better catalytic activity than the Vulcan-20%Pt in DMFC. In the case of Vulcan-40% Pt-doped Cerium, this material exhibits better catalytic activity than the Vulcan-40% Pt in DMFC, DEFC and HPEMFC. Finally, I propose a theory that explains the reason why the

Climate change, fire and the carbon balance

International Nuclear Information System (INIS)

Amiro, B.; Flannigan, M.

2004-01-01

On average, forest fires have burned 2 to 3 million hectares annually in Canada over the last twenty years. Over the last 40 years, this amounts to 20 per cent of the amount of carbon released through fossil fuel emissions in Canada. This paper analyses the extent to which climate change may contribute to a disturbance in the carbon balance due to increased fire activity. In addition, data from FLUXNET-Canada was examined, indicating that carbon fluxes from younger forests show dramatic changes in diurnal carbon flux patterns, caused by reduced photosynthetic uptake during the day and less root respiration at night. Increases in fire are expected throughout much of the boreal forest towards the end of this century, with a lengthening of the fire season and increases in severity and intensity. It was concluded that there is the possibility of a positive feedback, where climate change could cause more fires, resulting in a greater release of carbon and thereby increasing greenhouse gas concentrations. Evidence that smoke promoted positive lightning strikes while reducing precipitation was also presented. It was suggested that certain self-limiting factors may prevent a run-away scenario. Changes to human and lightning ignition patterns, for example, may have an impact. It was also suggested that research efforts should focus on refining climate change estimates that account for landscape change and other aspects that control fire in Canada. 9 refs., 2 figs

Carbon Impact Analytics - Designing low carbon indices based on Carbon Impact Analytics indicators

International Nuclear Information System (INIS)

2016-01-01

Investors are increasingly exposed to carbon risks and now face the challenge of managing these risks and developing climate-resilient investment strategies. Carbon Impact Analytics (CIA), an innovative methodology for analyzing the full carbon impact of a portfolio or index, equips investors and asset managers with the tools necessary to reduce their climate-related risks but also to seize the opportunities offered by the ongoing energy transition. Investors, asset managers and other financial institutions may use CIA results to: - measure and manage risks, - optimize their contribution to the energy transition, - seize opportunities associated with climate change mitigation, - report on GHG emissions and savings (for regulatory purposes or voluntarily), - engage in dialogue with companies, - reallocate investment portfolios, - and build new low-carbon indices. In this report, Carbone 4 offers a detailed look into how CIA indicators can be used to either 1) reallocate an existing portfolio or index to achieve maximal carbon performance or 2) build new low carbon indices from the ground up, drawn from Carbone 4's ever-growing database of CIA-analyzed firms. Two main levers were used to optimize CIA output: 1. Sectorial reallocation: exclusion of fossil fuel-related sectors or insertion of low carbon pure players; 2. Intra-sectorial reallocation: best-in-class approach within a sector. Sectorial and intra-sectorial methods may be applied in conjunction with one another to maximize results. For example, a best-in-class + fossil fuel-free index may be constructed by first excluding the fossil fuel sector and then applying a CIA best-in-class approach to all remaining sectors. This report offers a detailed look into how CIA indicators can be used to rework portfolios or indices to maximize carbon performance or to build low carbon indices from the ground up. These methods are illustrated via two preliminary examples of indices designed by Carbone 4: the reallocated

Unique effect of mechanical crushing on the electrochemical intercalation of lithium in carbons of different morphologies; Effet unique du broyage mecanique sur l`intercalation electrochimique du lithium dans des carbones de morphologies differentes

Energy Technology Data Exchange (ETDEWEB)

Salver-Disma, F.; Tarascon, J.M. [Universite de Picardie, 80 - Amiens (France)

1996-12-31

Lithium ion batteries use an oxide as a positive electrode and a carbon material as a negative electrode. The performances of carbon electrodes have rapidly evolved during the last years thanks to the substitution of soft carbons of Conoco or MCMB-2510 type by graphites (F-399, MCMB-2528) and then by hard carbons. These high capacity carbons (700 mAh/g) have higher service life and volume capacity than graphites but their irreversible losses are greater (>20%). In this work, materials with similar electrochemical performances are prepared by mechanical crushing. Mechanical crushing allows to obtain a wide range of carbon materials with various morphologies, specific surfaces and levels of disorder. The formation of the passivation film is directly linked with the surface of materials. A reaction scheme of the reversible and irreversible capacities has been defined and has permitted to obtain compounds with reversible capacities of 720 mAh/g (2 lithium for 6 carbon). (J.S.)

Unique effect of mechanical crushing on the electrochemical intercalation of lithium in carbons of different morphologies; Effet unique du broyage mecanique sur l`intercalation electrochimique du lithium dans des carbones de morphologies differentes

Energy Technology Data Exchange (ETDEWEB)

Salver-Disma, F; Tarascon, J M [Universite de Picardie, 80 - Amiens (France)

1997-12-31

Lithium ion batteries use an oxide as a positive electrode and a carbon material as a negative electrode. The performances of carbon electrodes have rapidly evolved during the last years thanks to the substitution of soft carbons of Conoco or MCMB-2510 type by graphites (F-399, MCMB-2528) and then by hard carbons. These high capacity carbons (700 mAh/g) have higher service life and volume capacity than graphites but their irreversible losses are greater (>20%). In this work, materials with similar electrochemical performances are prepared by mechanical crushing. Mechanical crushing allows to obtain a wide range of carbon materials with various morphologies, specific surfaces and levels of disorder. The formation of the passivation film is directly linked with the surface of materials. A reaction scheme of the reversible and irreversible capacities has been defined and has permitted to obtain compounds with reversible capacities of 720 mAh/g (2 lithium for 6 carbon). (J.S.)

Carbon tetrachloride desorption from activated carbon

International Nuclear Information System (INIS)

Jonas, L.A.; Sansone, E.B.

1981-01-01

Carbon tetrachloride was desorbed from a granular activated carbon subsequent to its adsorption under various vapor exposure periods. The varied conditions of exposure resulted in a range of partially saturated carbon beds which, when followed by a constant flow rate for desorption, generated different forms of the desorbing concentration versus time curve. A method of analyzing the desorption curves is presented which permits extraction of the various desorbing rates from the different desorption and to relate this to the time required for such regeneration. The Wheeler desorption kinetic equation was used to calculate the pseudo first order desorption rate constant for the carbon. The desorption rate constant was found to increase monotonically with increasing saturation of the bed, permitting the calculation of the maximum desorption rate constant for the carbon at 100% saturation. The Retentivity Index of the carbon, defined as the dimensionless ratio of the adsorption to the desorption rate constant, was found to be 681

Dynamics of soil carbon stocks due to large-scale land use changes across the former Soviet Union during the 20th century

Science.gov (United States)

Kurganova, Irina; Prishchepov, Alexander V.; Schierhorn, Florian; Lopes de Gerenyu, Valentin; Müller, Daniel; Kuzyakov, Yakov

2016-04-01

Land use change is a major driver of land-atmosphere carbon (C) fluxes. The largest net C fluxes caused by LUC are attributed to the conversion of native unmanaged ecosystems to croplands and vice versa. Here, we present the changes of soil organic carbon (SOC) stocks in response to large-scale land use changes in the former Soviet Union from 1953-2012. Widespread and rapid conversion of native ecosystems to croplands occurred in the course of the Virgin Lands Campaign (VLC) between 1954 to 1963 in the Soviet Union, when more than 45 million hectares (Mha) were ploughed in south-eastern Russia and northern Kazakhstan in order to expand domestic food production. After 1991, the collapse of the Soviet Union triggered the abandonment of around 75 Mha across the post-Soviet states. To assess SOC dynamics, we generated a static cropland mask for 2009 based on three global cropland maps. We used the cropland mask to spatially disaggregate annual sown area statistics at province level based on the suitability of each plot for crop production, which yielded land use maps for each year from 1954 to 2012 for all post-Soviet states. To estimate the SOC-dynamics due to the VLC and post-Soviet croplands abandonment, we used available experimental data, own field measurements, and soil maps. A bookkeeping approach was applied to assess the total changes in SOC-stocks in response to large-scale land use changes in the former Soviet Union. The massive croplands expansion during VLC resulted in a substantial loss of SOC - 611±47 Mt C and 241±11 Mt C for the upper 0-50 cm soil layer during the first 20 years of cultivation for Russia and Kazakhstan, respectively. These magnitudes are similar to C losses due to the plowing up of the prairies in USA in the mid-1930s. The total SOC sequestration due to post-Soviet croplands abandonment was estimated at 72.2±6.0 Mt C per year from 1991 to 2010. This amount of carbon equals about 40% of the current fossil fuel emission for this

Preparation and characterization of flake graphite/silicon/carbon spherical composite as anode materials for lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Lai Jun [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Guo Huajun, E-mail: Lai_jun_@126.com [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Wang Zhixing; Li Xinhai; Zhang Xiaoping; Wu Feixiang; Yue Peng [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China)

2012-07-25

Highlights: Black-Right-Pointing-Pointer Flake graphite/silicon/carbon composite is synthesized via spray drying. Black-Right-Pointing-Pointer Flake graphite of {approx}0.5 {mu}m and glucose are used to prepare the composite. Black-Right-Pointing-Pointer The as-prepared composite shows spherical and porous appearance. Black-Right-Pointing-Pointer The composite shows nearly the same cycleability as commercial graphite in 20 cycles. Black-Right-Pointing-Pointer The composite shows a reversible capacity of 552 mAh/g at the 20th cycle. - Abstract: Using nano-Si, glucose and flake graphite of {approx}0.5 {mu}m as raw materials, flake graphite/silicon/carbon composite is successfully synthesized via spray drying and subsequent pyrolysis. The samples are characterized by XRD, SEM, TEM and electrochemical measurements. The composite is composed of flake graphite, nano-Si and amorphous glucose-pyrolyzed carbon and presents good spherical appearance. Some micron pores arising from the decomposition of glucose exist on the surface of the composite particles. The composite has a high reversible capacity of 602.7 mAh/g with an initial coulombic efficiency of 69.71%, and shows nearly the same cycleability as the commercial graphite in 20 cycles. Both the glucose-pyrolyzed carbon and the micron pores play important roles in improving the cycleability of the composite. The flake graphite/silicon/carbon composite electrode is a potential alternative to graphite for high energy-density lithium ion batteries.