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1

Method of scrubbing acid gases from gas mixtures  

SciTech Connect

A process for scrubbing acid gases, especially carbon dioxide, from gas mixtures with an aqueous amine solution serving as the scrubbing liquid in which hexamethylene diamine serves as the amine. The concentration of the hexamethylene diamine in the aqueous solution is 5 to 40% by weight, preferably 25 to 35% by weight.

Beran, F.; Gerhards, H.J.; Kohler, P.; Lassmann, E.

1981-07-21

2

Clostridium stain which produces acetic acid from waste gases  

DOEpatents

A method and apparatus for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various organic acids or alcohols by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified. In an exemplary recovery process, the bioreactor raffinate is passed through an extraction chamber into which one or more non-inhibitory solvents are simultaneously introduced to extract the product. Then, the product is separated from the solvent by distillation. Gas conversion rates can be maximized by use of centrifuges, hollow fiber membranes, or other means of ultrafiltration to return entrained anaerobic bacteria from the bioreactor raffinate to the bioreactor itself, thus insuring the highest possible cell concentration.

Gaddy, James L. (2207 Tall Oaks Dr., Fayetteville, AR 72703)

1997-01-01

3

Processes to remove acid forming gases from exhaust gases  

DOEpatents

The present invention relates to a process for reducing the concentration of NO in a gas, which process comprises: (A) contacting a gas sample containing NO with a gaseous oxidizing agent to oxidize the NO to NO.sub.2 ; (B) contacting the gas sample of step (A) comprising NO.sub.2 with an aqueous reagent of bisulfite/sulfite and a compound selected from urea, sulfamic acid, hydrazinium ion, hydrazoic acid, nitroaniline, sulfanilamide, sulfanilic acid, mercaptopropanoic acid, mercaptosuccinic acid, cysteine or combinations thereof at between about 0.degree. and 100.degree. C. at a pH of between about 1 and 7 for between about 0.01 and 60 sec; and (C) optionally contacting the reaction product of step (A) with conventional chemical reagents to reduce the concentrations of the organic products of the reaction in step (B) to environ-mentally acceptable levels. Urea or sulfamic acid are preferred, especially sulfamic acid, and step (C) is not necessary or performed.

Chang, Shih-Ger (El Cerrito, CA)

1994-01-01

4

What are functional ionic liquids for the absorption of acidic gases?  

PubMed

As a kind of novel and efficient material, ionic liquids (ILs) are used for capture of acidic gases including SO2 and CO2 from flue gas. Due to very low content of acidic gases in flue gas, it is important to find functional ILs to absorb the acidic gases. However, up to now, there is no criterion to distinguish if the ILs are functional or not before use, which greatly influences the design of functional ILs. In this work, a series of ILs were synthesized and used to determine functional or normal ILs for the capture of acidic gases. It has been found that the pKa of organic acids forming the anion of ILs can be used to differentiate functional ILs from normal ILs for the capture of acidic gases from flue gas. If the pKa of an organic acid is larger than that of sulfurous acid (or carbonic acid), the ILs formed by the organic acid can be called functional ILs for SO2 (or CO2) capture, and it can have a high absorption capacity of SO2 (or CO2) with low SO2 (or CO2) concentrations. If not, the IL is just a normal IL. The pKa of organic acids can also be used to explain the absorption mechanism and guide the synthesis of functional ILs. PMID:23360403

Ren, Shuhang; Hou, Yucui; Tian, Shidong; Chen, Xiumei; Wu, Weize

2013-02-28

5

CMDL/Carbon Cycle Gases Group Standards Preparation and Stability.  

National Technical Information Service (NTIS)

The NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) Carbon Cycle Gases Group (CCGG) methods and materials for air standards preparation are presented in detail. Atmospheric natural air standards are prepared in aluminum cylinders as reference ga...

D. Kitzis, C. Zhao

1999-01-01

6

Apparatus for neutralizing acidic or acid-containing pollutants in furnace flue gases  

Microsoft Academic Search

An apparatus for neutralizing acidic or acid-containing pollutants in furnace flue gases comprising a flue gas duct having an inner pipe suspended therein and arranged so that the flue gases can flow both inside and outside the pipe. Preferably, the gases flow upwards around the outside of the pipe to an outlet zone. Atomizers project into the inner pipe for

Ch. Marnet; B. Kassebohm

1984-01-01

7

Method for removing acid gases from a gaseous stream  

DOEpatents

In a process for hydrocracking a heavy aromatic polynuclear carbonaceous feedstock containing reactive alkaline constituents to produce liquid hydrocarbon fuels boiling below about 475.degree. C. at atmospheric pressure by contacting the feedstock with hydrogen in the presence of a molten metal halide catalyst, thereafter separating a gaseous stream containing hydrogen, at least a portion of the hydrocarbon fuels and acid gases from the molten metal halide and regenerating the molten metal halide, thereby producing a purified molten metal halide stream for recycle to the hydrocracking zone, an improvement comprising; contacting the gaseous acid gas, hydrogen and hydrocarbon fuels-containing stream with the feedstock containing reactive alkaline constituents to remove acid gases from the acid gas containing stream. Optionally at least a portion of the hydrocarbon fuels are separated from gaseous stream containing hydrogen, hydrocarbon fuels and acid gases prior to contacting the gaseous stream with the feedstock.

Gorin, Everett (San Rafael, CA); Zielke, Clyde W. (McMurray, PA)

1981-01-01

8

Immersing carbon nanotubes in cold atomic gases  

NASA Astrophysics Data System (ADS)

We investigate the sympathetic relaxation of a free-standing, vibrating carbon nanotube that is mounted on an atom chip and is immersed in a cloud of ultracold atoms. Gas atoms colliding with the nanotube excite phonons via a Casimir-Polder potential. We use Fermi's golden rule to estimate the relaxation rates for relevant experimental parameters and develop a fully dynamic theory of relaxation for the multimode phononic field embedded in a thermal atomic reservoir. Based on currently available experimental data, we identify the relaxation rates as a function of atom density and temperature that are required for sympathetic ground-state cooling of carbon nanotubes.

Weiß, C. T.; Mironova, P. V.; Fortágh, J.; Schleich, W. P.; Walser, R.

2013-10-01

9

Adsorption of gases on carbon molecular sieves  

SciTech Connect

Adsorption on carbon molecular sieves (CMS) prepared by coke deposition has become an interesting area of adsorption due to its microporous nature and favorable separation factor on size and shape selectivity basis for many gaseous systems. In the present work CMS was synthesized from coconut shell through three major steps, namely, carbonization, activation, and coke deposition by hydrocarbon cracking. The crushed, washed, and sieved granules of coconut shell (particle size 2--3 mm) were pretreated with sodium silicate solution and oven-dried at 150 C to create the inorganic sites necessary for coke deposition. Carbonization and activation of the dried granules were carried out at 800 C, for 30 min each. The activated char thus produced was subjected to hydrocarbon cracking at 600 C for periods varying from 30 to 180 min. The product samples were characterized in terms of adsorption isotherm, kinetic adsorption curve, surface area, pore volume, pore size distribution, and characteristic energy for adsorption by using O[sub 2], N[sub 2], C[sub 2]H[sub 2], CO[sub 2], C[sub 3]H[sub 6], and CH[sub 4].

Vyas, S.N.; Patwardhan, S.R.; Vijayalakshmi, S. (Indian Inst. of Technology, Bombay (India). Dept. of Chemical Engineering); Ganesh, K.S. (Hindustan Petroleum Corp. Ltd., Bombay (India))

1994-12-01

10

MULTIPOLLUTANT MERCURY AND ACID GASES CONTROL TECHNOLOGY  

EPA Science Inventory

Plans are to continue testing for acid gas, mercury and NOx removal on baseline CFB operation with lime slurry, then use modified lime hydrates and slurries, and modified calcium silicates as additives for enhanced mercury and SO2 removal. Also, data from a coal-fired utility b...

11

21 CFR 201.161 - Carbon dioxide and certain other gases.  

Code of Federal Regulations, 2010 CFR

...Other Exemptions § 201.161 Carbon dioxide and certain other gases. (a) Carbon dioxide, cyclopropane, ethylene, helium, and nitrous oxide gases intended for drug use are exempted from the requirements of § 201.100(b) (2), (3),...

2010-04-01

12

40 CFR 60.54a - Standard for municipal waste combustor acid gases.  

Code of Federal Regulations, 2011 CFR

...municipal waste combustor acid gases. (a)-(b) [Reserved...from that affected facility any gases that contain sulfur dioxide...from that affected facility any gases that contain hydrogen chloride in excess of 5...

2011-07-01

13

40 CFR 60.54a - Standard for municipal waste combustor acid gases.  

Code of Federal Regulations, 2012 CFR

...municipal waste combustor acid gases. (a)-(b) [Reserved...from that affected facility any gases that contain sulfur dioxide...from that affected facility any gases that contain hydrogen chloride in excess of 5...

2012-07-01

14

40 CFR 60.54a - Standard for municipal waste combustor acid gases.  

Code of Federal Regulations, 2013 CFR

...municipal waste combustor acid gases. (a)-(b) [Reserved...from that affected facility any gases that contain sulfur dioxide...from that affected facility any gases that contain hydrogen chloride in excess of 5...

2013-07-01

15

40 CFR 60.54a - Standard for municipal waste combustor acid gases.  

Code of Federal Regulations, 2010 CFR

...municipal waste combustor acid gases. (a)-(b) [Reserved...from that affected facility any gases that contain sulfur dioxide...from that affected facility any gases that contain hydrogen chloride in excess of 5...

2010-07-01

16

ACID GASES IN CO2-RICH SUBSURFACE GEOLOGIC ENVIRONMENTS  

SciTech Connect

The analysis of species behavior involving dilute fluid environments has been crucial for the advance of modern solvation thermodynamics through molecular-based formalisms to guide the development of macroscopic regression tools in the description of fluid behavior and correlation of experimental data (Chialvo 2013). Dilute fluid environments involving geologic formations are of great theoretical and practical relevance regardless of the thermodynamic state conditions. The most challenging systems are those involving highly compressible and reactive confined environments, i.e., where small perturbations of pressure and/or temperature can trigger considerable density changes. This in turn can alter significantly the species solvation, their preferential solvation, and consequently, their reactivity with one another and with the surrounding mineral surfaces whose outcome is the modification of the substrate porosity and permeability, and ultimately, the integrity of the mineral substrates. Considering that changes in porosity and permeability resulting from dissolution and precipitation phenomena in confined environments are at the core of the aqueous CO2-mineral interactions, and that caprock integrity (e.g., sealing capacity) depends on these key parameters, it is imperative to gain fundamental understanding of the mineral-fluid interfacial phenomena and fluid-fluid equilibria under mineral confinement at subsurface conditions. In order to undertand the potential effects of acid gases as contaminants of supercritical CO2 streams, in the next section we will discuss the thermodynamic behavior of CO2 fluid systems by addressing two crucial issues in the context of carbon capture, utilization and sequestration (CCUS) technologies: (i) Why should we consider (acid gas) CO2 impurities? and (ii) Why are CO2 fluid - mineral interactions of paramount relevance?

Chialvo, Ariel A [ORNL] [ORNL; Vlcek, Lukas [ORNL] [ORNL; Cole, David [Ohio State University] [Ohio State University

2013-01-01

17

Process for removal of ammonia and acid gases from contaminated waters  

DOEpatents

Contaminating basic gases, i.e., ammonia and acid gases, e.g., carbon dioxide, are removed from process waters or waste waters in a combined extraction and stripping process. Ammonia in the form of ammonium ion is extracted by an immiscible organic phase comprising a liquid cation exchange component, especially an organic phosphoric acid derivative, and preferably di-2-ethyl hexyl phosphoric acid, dissolved in an alkyl hydrocarbon, aryl hydrocarbon, higher alcohol, oxygenated hydrocarbon, halogenated hydrocarbon, and mixtures thereof. Concurrently, the acidic gaseous contaminants are stripped from the process or waste waters by stripping with stream, air, nitrogen, or the like. The liquid cation exchange component has the ammonia stripped therefrom by heating, and the component may be recycled to extract additional amounts of ammonia.

King, C.J.; Mackenzie, P.D.

1982-09-03

18

Acetic Acid Catalyzed Carbon Aerogels  

Microsoft Academic Search

We prepared carbon aerogels with a wide range of structural properties and densities using the weak acetic acid as a catalyst. Two series of acetic acid catalyzed carbon aerogels with different dilution of the catalyst and the monomers were investigated accurately. Structural investigation was performed via (U)SAXS, gas sorption and SEM. The pore and particle size can be tailored according

R. Brandt; R. Petricevic; H. Pröbstle; J. Fricke

2003-01-01

19

Organic acids tunably catalyze carbonic acid decomposition.  

PubMed

Density functional theory calculations predict that the gas-phase decomposition of carbonic acid, a high-energy, 1,3-hydrogen atom transfer reaction, can be catalyzed by a monocarboxylic acid or a dicarboxylic acid, including carbonic acid itself. Carboxylic acids are found to be more effective catalysts than water. Among the carboxylic acids, the monocarboxylic acids outperform the dicarboxylic ones wherein the presence of an intramolecular hydrogen bond hampers the hydrogen transfer. Further, the calculations reveal a direct correlation between the catalytic activity of a monocarboxylic acid and its pKa, in contrast to prior assumptions about carboxylic-acid-catalyzed hydrogen-transfer reactions. The catalytic efficacy of a dicarboxylic acid, on the other hand, is significantly affected by the strength of an intramolecular hydrogen bond. Transition-state theory estimates indicate that effective rate constants for the acid-catalyzed decomposition are four orders-of-magnitude larger than those for the water-catalyzed reaction. These results offer new insights into the determinants of general acid catalysis with potentially broad implications. PMID:24933150

Kumar, Manoj; Busch, Daryle H; Subramaniam, Bala; Thompson, Ward H

2014-07-10

20

Biological production of acetic acid from waste gases with Clostridium ljungdahlii  

DOEpatents

A method and apparatus for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various organic acids or alcohols by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified. In an exemplary recovery process, the bioreactor raffinate is passed through an extraction chamber into which one or more non-inhibitory solvents are simultaneously introduced to extract the product. Then, the product is separated from the solvent by distillation. Gas conversion rates can be maximized by use of centrifuges, hollow fiber membranes, or other means of ultrafiltration to return entrained anaerobic bacteria from the bioreactor raffinate to the bioreactor itself, thus insuring the highest possible cell concentration.

Gaddy, James L. (Fayetteville, AR)

1998-01-01

21

Biological production of acetic acid from waste gases with Clostridium ljungdahlii  

DOEpatents

A method and apparatus are disclosed for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various organic acids or alcohols by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified. In an exemplary recovery process, the bioreactor raffinate is passed through an extraction chamber into which one or more non-inhibitory solvents are simultaneously introduced to extract the product. Then, the product is separated from the solvent by distillation. Gas conversion rates can be maximized by use of centrifuges, hollow fiber membranes, or other means of ultrafiltration to return entrained anaerobic bacteria from the bioreactor raffinate to the bioreactor itself, thus insuring the highest possible cell concentration. 5 figs.

Gaddy, J.L.

1998-09-15

22

Radiolysis gases from nitric acid solutions containing HSA and HAN  

SciTech Connect

The concentration of hydrogen (H{sub 2}) in the radiolytically produced off-gas from 2.76-4.25M HNO{sub 3} solutions is greatly reduced by dilution in the presence of HSA (sulfamic acid) and HAN (hydroxylamine nitrate). This dilution continues at a constant rate until the HSA and HAN are exhausted. The generation rate, G(H{sub 2}), was not affected by these two compounds giving a value of 0.201 mol/100 eV for 2.77M NO{sub 3}{sup -}. The other radiolysis gases produced are O{sub 2}, N{sub 2}, and N{sub 2}O, the later two due to reduction of nitrous acid by HSA and HAN respectively. At high nitrate concentrations, >2.8M, and in the presence of HAN the total off-gas production rate is greatly reduced. This may be due to reaction of nitrate and HAN to produce oxygen reactive compounds such as HNO which can react with dissolved O{sub 2} to regenerate nitrate directly, by-passing nitrous acid. The initial reduction in the off-gas rate is lost after destruction of the HAN.

Smith, J.R. [Westinghouse Svannah River Company, Aiken, SC (United States)

1995-12-31

23

40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2011 CFR

...municipal waste combustor acid gases, expressed as sulfur dioxide and hydrogen chloride, are specified...that affected facility any gases that contain sulfur dioxide...that affected facility any gases that contain hydrogen chloride in excess of...

2011-07-01

24

40 CFR 60.33b - Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2013 CFR

...waste combustor acid gases, expressed as sulfur dioxide and hydrogen chloride, are specified...emission limit for hydrogen chloride contained in the gases discharged to the...emission limit for hydrogen chloride contained in the gases discharged to...

2013-07-01

25

40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2013 CFR

...municipal waste combustor acid gases, expressed as sulfur dioxide and hydrogen chloride, are specified...that affected facility any gases that contain sulfur dioxide...that affected facility any gases that contain hydrogen chloride in excess of...

2013-07-01

26

40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2012 CFR

...municipal waste combustor acid gases, expressed as sulfur dioxide and hydrogen chloride, are specified...that affected facility any gases that contain sulfur dioxide...that affected facility any gases that contain hydrogen chloride in excess of...

2012-07-01

27

40 CFR 60.33b - Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2011 CFR

...waste combustor acid gases, expressed as sulfur dioxide and hydrogen chloride, are specified...emission limit for hydrogen chloride contained in the gases discharged to the...emission limit for hydrogen chloride contained in the gases discharged to...

2011-07-01

28

40 CFR 60.33b - Emission guidelines for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2012 CFR

...waste combustor acid gases, expressed as sulfur dioxide and hydrogen chloride, are specified...emission limit for hydrogen chloride contained in the gases discharged to the...emission limit for hydrogen chloride contained in the gases discharged to...

2012-07-01

29

40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2010 CFR

...municipal waste combustor acid gases, expressed as sulfur dioxide and hydrogen chloride, are specified...that affected facility any gases that contain sulfur dioxide...that affected facility any gases that contain hydrogen chloride in excess of...

2010-07-01

30

Performance and Problems of Claus Plant Operation on Coke Oven Acid Gases  

Microsoft Academic Search

The application of Claus Plant sulfur recovery units to the coke oven gas (COG) acid gases at three Bethlehem Steel Corporation plants is discussed. While many of the problems encountered are not unique to coke oven gas-derived acid gases, it was found that special consideration must be given to the effect of components not normally encountered in the typical Claus

Otto A. Homberg; Alan H. Singleton

1975-01-01

31

Joseph Black, carbon dioxide, latent heat, and the beginnings of the discovery of the respiratory gases.  

PubMed

The discovery of carbon dioxide by Joseph Black (1728-1799) marked a new era of research on the respiratory gases. His initial interest was in alkalis such as limewater that were thought to be useful in the treatment of renal stone. When he studied magnesium carbonate, he found that when this was heated or exposed to acid, a gas was evolved that he called "fixed air" because it had been combined with a solid material. He showed that the new gas extinguished a flame, that it could not support life, and that it was present in gas exhaled from the lung. Within a few years of his discovery, hydrogen, nitrogen, and oxygen were also isolated. Thus arguably Black's work started the avalanche of research on the respiratory gases carried out by Priestley, Scheele, Lavoisier, and Cavendish. Black then turned his attention to heat and he was the first person to describe latent heat, that is the heat added or lost when a liquid changes its state, for example when water changes to ice or steam. Latent heat is a key concept in thermal physiology because of the heat lost when sweat evaporates. Black was a friend of the young James Watt (1736-1819) who was responsible for the development of early steam engines. Watt was puzzled why so much cooling was necessary to condense steam into water, and Black realized that the answer was the latent heat. The resulting improvements in steam engines ushered in the Industrial Revolution. PMID:24682452

West, John B

2014-06-15

32

Dry scrubbing of acid gases in recirculating cyclones.  

PubMed

This paper describes a laboratory-scale study on the use of recirculating cyclones as reaction chambers for dry scrubbing of gaseous HCl with solid slaked lime particles. This gas cleaning system combines a numerically optimized reverse flow gas cyclone (RS_VHE geometry) with a straight-through cyclone concentrator, which simultaneously increases the capture of the solid particles and promotes their partial recirculation. A laboratory-scale study was undertaken to test this technology and to compare its performance to a modified Stairmand HE reverse flow cyclone without recirculation. The experimental conditions were: reaction temperature approximately 326 K, gas flow rate approximately 2.9 x 10(-4) Nm(3) s(-1) and relative humidity of the gas approximately 8.5%. The experimental variables tested were the solids load (1.0-9.2 x 10(-7) kg s(-1)) and HCl concentration (0.4-2.8 x 10(-2) mol m(-3)) in the inlet gas. The experimentally obtained particulate removal efficiencies with the recirculating cyclones ( approximately 98%) were higher than those obtained with the Stairmand HE cyclone ( approximately 93%), with the additional advantage of having significantly lower pressure drop. As for the acid removal efficiencies ( approximately 10-96%), no significant differences were found between the two systems tested under the same experimental conditions. The possibility of using optimized recirculating cyclones for gas cleaning in a dry scrubbing process is very promising, since this is a low cost technology, highly efficient both for the removal of acid gases and for the capture of solid particles, which has the advantage of not requiring a post-reaction de-duster. PMID:17360111

Chibante, Vânia; Fonseca, Ana; Salcedo, Romualdo

2007-06-18

33

Atmospheric Trace Gases from the Carbon Dioxide Information Analysis Center (CDIAC)  

DOE Data Explorer

CDIAC products are indexed and searchable through a customized interface powered by ORNL's Mercury search engine. Products include numeric data packages, publications, trend data, atlases, models, etc. and can be searched for by subject area, keywords, authors, product numbers, time periods, collection sites, spatial references, etc. Some of the collections may also be included in the CDIAC publication, Trends Online: A Compendium of Global Change Data. Most data sets, many with numerous data files, are free to download from CDIAC's ftp area. The collections under the CDIAC heading of Atmospheric Trace Gases include: Atmospheric Carbon Dioxide, Atmospheric Methane, Atmospheric Carbon Monoxide, Atmospheric Hydrogen, Isotopes in Greenhouse Gases, Radionuclides, Aerosols, and Other Trace Gases.

34

OPERATION OF A SULFURIC ACID PLANT USING BLENDED COPPER SMELTER GASES  

EPA Science Inventory

A high degree of control of SOx emissions at copper smelters can be obtained by blending reverberatory furnace gases with gases from roasters and converters and using the combined stream as feed to a sulfuric acid plant. The Bor Copper Smelter in Bor, Yugoslavia, experimented wit...

35

Radiolysis gases from nitric acid solutions containing HSA and HAN  

SciTech Connect

The concentration of hydrogen (H{sub 2}) in the radiolytically produced off-gas from 2.76-4.25M HNO{sub 3}/PU solutions has been found to be greatly reduced in the presence of sulfamic acid (HSA) and hydroxylamine nitrate (HAN). The H{sub 2} concentration ([H{sub 2}]) is reduced from 35 percent to about 4 percent by dilution caused from an increase in the production rates of nitrogen (N{sub 2}), nitrous oxide (N{sub 2}O), and oxygen (O{sub 2}) gases. The generation rate of H{sub 2} was not affected by HSA or HAN giving a measured radiolytic yield, G(H{sub 2}), value of 0.201 molecules/100 eV for 2.765M NO{sub 3}{sup -} solution (a value of 0.213 is predicted from previous data). The G(H{sub 2}) values are dependent on the solution nitrate concentration ([NO{sub 3}{sup -}]). The generation rates of N{sub 2}, N{sub 2}O, and O{sub 2} are not dependent on the [NO{sub 3}{sup -}] in this narrow range, but are dependent on the presence of HSA and the concentration of HAN. The percentage [H{sub 2}] for the 2.5 to 3.0M NO{sub 3}{sup -} range expected in the off- from the FB-Line Pu{sup +3} Hold Tanks is conservatively estimated to be about 3.5 to 4.5 % for Pu + 3 solutions initially containing 0.023M HAN/0.165M HSA. The upper limit [H{sub 2}] may actually be about 4.1 % (4.3 % at 90 % confidence limits) but more {open_quotes}initial{close_quotes} off-gas rate data is needed at about 2.9M [NO{sub 3}{sup -}] in Pu{sup +3} solution for verification. Addition of ascorbic acid had no effect on the off-gas rate of Pu{sup +3} solutions containing HSA and NO{sub 3}{sup -} concentrations higher than those expected in the hold tanks. The maximum {open_quotes}hold time{close_quotes} for 50 grams/liter Pu{sup +3}/0.165M HSA/0.023M HAN/2.5-3.0M HNO{sub 3} solution is 20.3{+-}2.1 days. After this time the HSA initially present will become exhausted and the [H{sub 2}] will increase to 35 %. This hold time may be longer in [NO{sub 3}{sup -}] < 3.0M, but again more study is needed.

Smith, J.R.

1994-10-28

36

CARBON DIOXIDE STANDARD EMISSIVITY BY MIXED GRAY-GASES MODEL  

Microsoft Academic Search

Conventional fossil fuels are of carbon-hydrogen composition. A number of alternative fuels, e.g., coal, lignite, are carbon-based fuels. The high temperature combustion of such fuels would generate carbon dioxide, and if hydrogen is present, water vapor. The knowledge of the emissivities of carbon dioxide and water vapor is very important in burner design and thermal efficiency calculations. The present work

IHAB H. FARAG; T. A. ALLAM

1982-01-01

37

Relation of Hydrogen and Methane to Carbon Monoxide in Exhaust Gases from Internal-Combustion Engines  

NASA Technical Reports Server (NTRS)

The relation of hydrogen and methane to carbon monoxide in the exhaust gases from internal-combustion engines operating on standard-grade aviation gasoline, fighting-grade aviation gasoline, hydrogenated safety fuel, laboratory diesel fuel, and auto diesel fuel was determined by analysis of the exhaust gases. Two liquid-cooled single-cylinder spark-ignition, one 9-cylinder radial air-cooled spark-ignition, and two liquid-cooled single-cylinder compression-ignition engines were used.

Gerrish, Harold C; Tessmann, Arthur M

1935-01-01

38

Plasma-chemical waste treatment of acid gases  

SciTech Connect

The research to date has shown that a H{sub 2}S waste-treatment process based on plasma-chemical dissociation technology is compatible with refinery and high-carbon-oxide acid-gas streams. The minor amounts of impurities produced in the plasma-chemical reactor should be treatable by an internal catalytic reduction step. Furthermore, the plasma-chemical technology appears to be more efficient and more economical than the current technology. The principal key to achieving high conversions with relatively low energies of dissociation is the concept of the high-velocity, cyclonic-flow pattern in the plasma reaction zone coupled with the recycling of unconverted hydrogen sulfide. Future work will include testing the effects of components that might be carried over to the plasma reactor by ``upset`` conditions in the amine purification system of a plant and testing the plasma-chemical process on other industrial wastes streams that contain potentially valuable chemical reagents. The strategy for the commercialization of this technology is to form a Cooperative Research and Development Agreement with the Institute of Hydrogen Energy and Plasma Technology of the Russian Scientific Center/Kurchatov Institute and with an American start-up company to develop an ``American`` version of the process and to build a commercial-scale demonstration unit in the United States. The timetable proposed would involve building a ``field test`` facility which would test the plasma-chemical reactor and sulfur recovery unit operations on an industrial hydrogen sulfide waste s at a scale large enough to obtain the energy and material balance data required for a final analysis of the commercial potential of this technology. The field test would then be followed by construction of a commercial demonstration unit in two to three years. The commercial demonstration unit would be a fully integrated plant consisting of one commercial-scale module.

Harkness, J.B.L.; Doctor, R.D.; Daniels, E.J.

1993-09-01

39

Natural sources of greenhouse gases: carbon dioxide emissions from volcanoes  

USGS Publications Warehouse

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

Gerlach, Terrence

1990-01-01

40

Ionic Liquids as Catalysts for Sulfuric Acid Production and Cleaning of Flue Gases  

Microsoft Academic Search

\\u000a The present paper is concerned with catalytic pollution abatement of sulfur and nitrogen oxides in flue gases from industrial\\u000a sources. Especially fundamental and applied research on industrial catalysts and their model systems is presented with regards\\u000a to cleaning of flue gases from fossil fuel based power plants and plants producing sulfuric acid. Combined DeSOx and DeNOx processes are very common

Rasmus Fehrmann; K. M. Eriksen; S. B. Rasmussen; J. Winnick

41

Process for recovery of sulfur from acid gases  

DOEpatents

Elemental sulfur is recovered from the H.sub.2 S present in gases derived from fossil fuels by heating the H.sub.2 S with CO.sub.2 in a high-temperature reactor in the presence of a catalyst selected as one which enhances the thermal dissociation of H.sub.2 S to H.sub.2 and S.sub.2. The equilibrium of the thermal decomposition of H.sub.2 S is shifted by the equilibration of the water-gas-shift reaction so as to favor elemental sulfur formation. The primary products of the overall reaction are S.sub.2, CO, H.sub.2 and H.sub.2 O. Small amounts of COS, SO.sub.2 and CS.sub.2 may also form. Rapid quenching of the reaction mixture results in a substantial increase in the efficiency of the conversion of H.sub.2 S to elemental sulfur. Plant economy is further advanced by treating the product gases to remove byproduct carbonyl sulfide by hydrolysis, which converts the COS back to CO.sub.2 and H.sub.2 S. Unreacted CO.sub.2 and H.sub.2 S are removed from the product gas and recycled to the reactor, leaving a gas consisting chiefly of H.sub.2 and CO, which has value either as a fuel or as a chemical feedstock and recovers the hydrogen value from the H.sub.2 S.

Towler, Gavin P. (Kirkbymoorside, GB2); Lynn, Scott (Pleasant Hill, CA)

1995-01-01

42

Experimental Determination of the Partitioning Behavior of Noble Gases Between Carbonate and Silicate Liquids  

NASA Astrophysics Data System (ADS)

Carbonatitic melts have been identified in the earth’s upper mantle and experimental evidence suggests that such melts are stable at mantle conditions. Due to high carbonatite/silicate partition coefficients for certain trace elements, and due to the low melting points, low viscosities and low dihedral angles of carbonatite liquids, these liquids play a significant role in trace element fractionation in the mantle. However, the solubilities of the noble gases in carbonatitic liquids are poorly constrained although initial data at low pressure (1 bar) surprisingly suggest that the noble gases are poorly soluble in carbonatite liquids [1]. Partitioning of noble gases relative to the parents of radiogenic noble gases - primarily U, Th and K - has consequences for the isotopic evolution of mantle noble gases, consequently determination of noble gas solubilities in carbonatite phases is of extreme interest for mantle geodynamics. Two-liquid experimental charges consisting of nephelenite and Na2CO3 were synthesized at 1145 C and pressures between 0.6 and 2.5 GPa in sealed Au-Pd capsules in a piston cylinder apparatus. The experimental runs were c. 12h in duration and the charges were quenched at >200 C min-1 to form two immiscibly separated glasses phases. The nephelenite glass starting material had been saturated with a noble gas mixture (0.5 He, 0.02 Ne, 0.48 Ar) prior to synthesis. This procedure introduced noble gases without creating a free gas phase. The noble gases (He and Ar only) were measured in 3 stages: 1) the capsule was pierced under vacuum and the ‘free gas’ residing in the capsule pore space was analysed; 2) the entire capsule was heated to 250 C and the gases liberated were analysed and 3) the nephelenite glass was melting by a CO2 laser and the gases liberated analysed. The first stage of the analysis was to measure any noble gases (principally He) that may have diffused out of the carbonatite during the quench or between the period (of a few weeks) between quench and analysis. The second stage was designed to extract noble gases by thermal decarbonation of the carbonate glass. The metal of the capsule itself was also measured, but this never contained any noble gas above blank levels. Our preliminary results show that the noble gases do not preferentially partition into carbonate liquids compared to silicate liquids: DHe(carbonate/silicate)=0.3-1.4 and DAr(carbonate/silicate)=0.15-0.17 (at 1 GPa) In a two phase carbonate - silicate system, the noble gases will essentially reside in the silicate portion of the system (particularly given that carbonatite liquids will represent a small volume fraction of the two phase magma). This partitioning behavior could nevertheless separate - decouple - noble gas isotope systematics from lithophile isotopes (Sr, Nd, Pb etc) as a significant fraction of these elements could partition into the carbonate phase while noble gases remain in the silicate portion of the magma. Further work investigating pressure, temperature and compositional effects on the noble gas partition coefficients is planned. References 1. Burnard, P., Toplis, M. J. and Medynski, S. (2010) Geochim. Cosmochim. Acta 74: 1672-1683.

Burnard, P.; Koga, K. T.

2010-12-01

43

EasyDelta: a spreadsheet for kinetic modeling of the stable carbon isotope composition of natural gases  

Microsoft Academic Search

A new kinetic model and an Excel© spreadsheet program for modeling the stable carbon isotope composition of natural gases is provided in this paper. The model and spreadsheet could be used to describe and predict changes in stable carbon isotopes of natural gases under both experimental and geological conditions with heating temperature or geological time. The user-friendly spreadsheet, based on

Yan-Rong Zou; Lianyuan Wang; Yanhua Shuai; Ping’an Peng

44

EasyDelta: A spreadsheet for kinetic modeling of the stable carbon isotope composition of natural gases  

Microsoft Academic Search

A new kinetic model and an Excel© spreadsheet program for modeling the stable carbon isotope composition of natural gases is provided in this paper. The model and spreadsheet could be used to describe and predict the variances in stable carbon isotope of natural gases under both experimental and geological conditions with heating temperature or geological time. It is a user-friendly

Yan-Rong Zou; Lianyuan Wang; Yanhua Shuai; Ping’an Peng

2005-01-01

45

Operational Characteristics of Effective Removal of H2S and NH3 Waste Gases by Activated Carbon Biofilter  

Microsoft Academic Search

Simultaneous removal of hydrogen sulfide (H2S) and am- gases. monia (NH3) gases from gaseous streams was studied in a biofilter packed with granule activated carbon. Extensive studies, including the effects of carbon (C) source on the growth of inoculated microorganisms and gas removal efficiency, product analysis, bioaerosol emission, pressure drop, and cost evaluation, were conducted. The results indicated that molasses

Ying-Chien Chung; Yu-Yen Lin; Ching-Ping Tseng

2004-01-01

46

The origins and concentrations of water, carbon, nitrogen and noble gases on Earth  

E-print Network

for subsequent loss. Doing so, the I-Pu-Xe age of the Earth becomes 50 Ma after start of solar system formation1 The origins and concentrations of water, carbon, nitrogen and noble gases on Earth Bernard Marty@crpg.cnrs-nancy.fr Submitted as a Frontiers article to Earth and Planetary Science Letters revised version, October 10, 2011

Paris-Sud XI, Université de

47

The Geostationary Remote Infrared Pollution Sounder (GRIPS): measurement of the carbon gases from space  

NASA Astrophysics Data System (ADS)

Climate change and air quality are the most pressing environmental issues of the 21st century. Despite decades of research, the sources and sinks of key greenhouse gases remain highly uncertain [IPCC1] making quantitative predictions of atmospheric composition and their impacts. The Geostationary Remote Infrared Pollution Sounder (GRIPS) is a multi-purpose instrument designed to reduce uncertainty associated with atmospheric radiative forcing. GRIPS will measure will measure greenhouse gases and aerosols - two of the most important elements in the earth's radiation budget. GRIPS will observe carbon dioxide (CO2), carbon monoxide (CO), methane (CH4), - the carbon gases, nitrous oxide (N2O), water vapor and aerosols with unprecedented precision through the atmosphere. The GRIPS instrument uses gas filter correlation radiometry (GFCR) to detect reflected and thermal IR radiation to detect the gases and the reflected solar radiation in the visible and short-wave infrared bands for aerosols. GRIPS is designed to have sensitivity down to the Earth's surface at ~2-8km nadir resolution. GRIPS can resolve CO2, CO, and CH4 anomalies in the planetary boundary layer and the free troposphere to quantify lofting, diurnal variations and longrange transport. With repeated measurements throughout the day GRIPS can maximize the number of cloud free measurements determining biogenic and anthropogenic sources, sinks, and fluxes. GRIPS is highly complementary to the Orbiting Carbon Observatory, OCO-2, the geostationary Tropospheric Emissions: Monitoring of Pollution (TEMPO) and Advanced Baseline Imager (ABI) and other existing and planned missions.

Schoeberl, M.; Dickerson, R.; Marshall, B. T.; McHugh, M.; Fish, C.; Bloom, H.

2013-09-01

48

Immersing carbon nano-tubes in cold atomic gases  

E-print Network

We investigate the sympathetic relaxation of a free-standing, vibrating carbon nano-tube that is mounted on an atom chip and is immersed in a cloud of ultra-cold atoms. Gas atoms colliding with the nano-tube excite phonons via a Casimir-Polder potential. We use Fermi's Golden Rule to estimate the relaxation rates for relevant experimental parameters and develop a fully dynamic theory of relaxation for the multi-mode phononic field embedded in a thermal atomic reservoir. Based on currently available experimental data, we identify the relaxation rates as a function of atom density and temperature that are required for sympathetic ground state cooling of carbon nano-tubes.

C. T. Weiß; P. V. Mironova; J. Fortágh; W. P. Schleich; R. Walser

2013-07-08

49

Acid sorption regeneration process using carbon dioxide  

DOEpatents

Carboxylic acids are sorbed from aqueous feedstocks onto a solid adsorbent in the presence of carbon dioxide under pressure. The acids are freed from the sorbent phase by a suitable regeneration method, one of which is treating them with an organic alkylamine solution thus forming an alkylamine-carboxylic acid complex which thermally decomposes to the desired carboxylic acid and the alkylamine.

King, C. Judson (Kensington, CA); Husson, Scott M. (Anderson, SC)

2001-01-01

50

Sorption of noble gases by solids, with reference to meteorites. II - Chromite and carbon. III - Sulfides, spinels, and other substances; on the origin of planetary gases  

NASA Technical Reports Server (NTRS)

The trapping of noble gases by chromite and carbon, two putative carriers of primordial noble gases in meteorites, was studied by synthesizing 19 samples in a Ne-Ar-Kr-Xe atmosphere at 440-720 K. Noble gas contents are found to approximately obey Henry's Law, but only slight correlations are found with composition, surface area, or adsorption temperature. Geometric mean distribution coefficients for bulk samples and HCl residues in 10 cu cm STP/g atm are: Xe 100, Kr 15, Ar 3.5, and Ne 0.62. Elemental fractionation data support the suggestion of Lewis et al. (1977) that chromite and carbon in C2 and C3 chondrites were formed by the reaction: Fe, Cr + 4CO yields (Fe, Cr)3O4 + 4C + carbides. In contrast to meteoritic minerals, the synthetic specimens show no isotopic fractionation of noble gases. In a subsequent study, attention is given to the cases of sulfides and spinels, on the way to consideration of the origin of planetary gases. Sulfides showed three distinctive trends relative to chromite or magnetite. The elemental fractionation pattern of Ar, Kr and Xe in meteorites, terrestrial rocks and planets resembles the adsorption patterns on the carbons, spinels, sulfides, and other solids studied. The high release temperature of meteoritic noble gases may be explained by transformation of the physisorbed or chemisorbed gas. The ready loss of meteoritic heavy gases on surficial oxidation is consistent with adsorption, as is the high abundance.

Yang, J.; Anders, E.

1982-01-01

51

Parametric study of ReaxFF simulation parameters for molecular dynamics modeling of reactive carbon gases  

NASA Astrophysics Data System (ADS)

The development of innovative carbon-based materials can be greatly facilitated by molecular modeling techniques. Although the Reax Force Field (ReaxFF) can be used to simulate the chemical behavior of carbon-based systems, the simulation settings required for accurate predictions have not been fully explored. Using the ReaxFF, molecular dynamics (MD) simulations are used to simulate the chemical behavior of pure carbon and hydrocarbon reactive gases that are involved in the formation of carbon structures such as graphite, buckyballs, amorphous carbon, and carbon nanotubes. It is determined that the maximum simulation time step that can be used in MD simulations with the ReaxFF is dependent on the simulated temperature and selected parameter set, as are the predicted reaction rates. It is also determined that different carbon-based reactive gases react at different rates, and that the predicted equilibrium structures are generally the same for the different ReaxFF parameter sets, except in the case of the predicted formation of large graphitic structures with the Chenoweth parameter set under specific conditions.

Jensen, Benjamin D.

52

Indoor and outdoor concentrations of inorganic acidic aerosols and gases  

SciTech Connect

Annular denuder-filter pack sampling systems were used to make indoor and outdoor measurements of aerosol strong H{sup +}, SO{sub 4}{sup 2{minus}}, NH{sub 4}{sup +}, NO{sub 3}{sup {minus}} and NO{sub 2}{sup {minus}}, and the gaseous pollutants SO{sub 2}, HNO{sub 3}, HONO and NH{sub 3} during summer and winter periods in Boston, Massachusetts. Outdoor levels of SO{sub 2}, HNO{sub 3}, H{sup +} and SO{sub 4}{sup 2{minus}} exceeded their indoor concentrations during both seasons. Winter indoor/outdoor ratios were lower than during the summer, probably due to lower air exchange rates during the winter period. During both monitoring periods, indoor/outdoor ratios of aerosol strong H{sub +} were 40-50% of the indoor/outdoor SO{sub 4}{sup 2{minus}} ratio. Since aerosol strong acidity is typically associated with SO{sub 4}{sup 2{minus}}, this finding is indicative of neutralization of the acidic aerosol by the higher indoor NH{sub 3} levels. Geometric mean indoor/outdoor NH{sub 3} ratios of 3.5 and 23 respectively were measured for the summer and winter sampling periods. For HONO, NH{sub 3}, NH{sub 4}{sup +} and NO{sub 2}{sup {minus}}, indoor concentrations were significantly higher than ambient levels. Indoor levels of NO{sub 3}{sup {minus}} were slightly less than outdoor concentrations.

Brauer, M.; Koutrakis, P.; Keeler, G.J.; Spengler, J.D. (Harvard Univ., Boston, MA (USA))

1991-02-01

53

Accounting for carbon cycle feedbacks in a comparison of the global warming effects of greenhouse gases  

NASA Astrophysics Data System (ADS)

Greenhouse gases other than CO2 make a significant contribution to human-induced climate change, and multi-gas mitigation strategies are cheaper to implement than those which limit CO2 emissions alone. Most practical multi-gas mitigation strategies require metrics to relate the climate warming effects of CO2 and other greenhouse gases. Global warming potential (GWP), defined as the ratio of time-integrated radiative forcing of a particular gas to that of CO2 following a unit mass emission, is the metric used in the Kyoto Protocol, and we define mean global temperature change potential (MGTP) as an equivalent metric of the temperature response. Here we show that carbon-climate feedbacks inflate the GWPs and MGTPs of methane and nitrous oxide by ~ 20% in coupled carbon-climate model simulations of the response to a pulse of 50 × 1990 emissions, due to a warming-induced release of CO2 from the land biosphere and ocean. The magnitude of this effect is expected to be dependent on the model, but it is not captured at all by the analytical models usually used to calculate metrics such as GWP. We argue that the omission of carbon cycle dynamics has led to a low bias of uncertain but potentially substantial magnitude in metrics of the global warming effect of other greenhouse gases, and we suggest that the carbon-climate feedback should be considered when greenhouse gas metrics are calculated and applied.

Gillett, Nathan P.; Damon Matthews, H.

2010-07-01

54

Mantle-derived helium and carbon in groundwaters and gases of Mount Etna, Italy  

Microsoft Academic Search

We report the first detailed investigation of both helium and carbon isotopes in groundwaters and gases of Mt. Etna, providing new insight into the distribution, origin and budget of magmatic gas release at this very active volcano [1]. A mantle-derived magmatic component, with ultimate3He\\/4He ratio of 6.9 ± 0.2 Ra and ?13C of about ?4‰, is identified in both types

Patrick Allard; Philippe Jean-Baptiste; Walter D'Alessandro; Francesco Parello; Bianca Parisi; Christine Flehoc

1997-01-01

55

Method and apparatus for separating gases based on electrically and magnetically enhanced monolithic carbon fiber composite sorbents  

DOEpatents

A method for separating gases or other fluids involves placing a magnetic field on a monolithic carbon fiber composite sorption material to more preferentially attract certain gases or other fluids to the sorption material to which a magnetic field is applied. This technique may be combined with the known "pressure swing adsorption" technique utilizing the same sorption material.

Judkins, Roddie R. (9917 Rainbow Dr., Knoxville, TN 37922); Burchell, Timothy D. (109 Greywood Pl., Oak Ridge, TN 37830)

1999-01-01

56

Method and apparatus for separating gases based on electrically and magnetically enhanced monolithic carbon fiber composite sorbents  

DOEpatents

A method for separating gases or other fluids involves placing a magnetic field on a monolithic carbon fiber composite sorption material to more preferentially attract certain gases or other fluids to the sorption material to which a magnetic field is applied. This technique may be combined with the known pressure swing adsorption'' technique utilizing the same sorption material. 1 fig.

Judkins, R.R.; Burchell, T.D.

1999-07-20

57

Origins of natural gases from marine strata in Northeastern Sichuan Basin (China) from carbon molecular moieties and isotopic data  

NASA Astrophysics Data System (ADS)

To determine the origin, maturity, formation mechanism and secondary process of marine natural gases in Northeastern Sichuan area, molecular moieties and carbon isotopic data of the Carboniferous and Triassic gases have been analyzed. Typical samples of marine gas precursors including low-maturity kerogen, dispersed liquid hydrocarbons (DLHs) in source rocks, residual kerogen and oil have been examined in a closed system, and several published geochemical diagrams of gas origins have been calibrated by using laboratory data. Results show that both Carboniferous and Triassic gases in the study area have a thermogenic origin. Migration leads to stronger compositional and weak isotopic fractionation, and is path dependent. Carboniferous gases and low-H2S gases are mainly formed by secondary cracking of oil, whereas high-H2S gases are clearly related to the TSR (Thermal Sulfate Reduction) process. Gases in NE Sichuan show a mixture of heavy (13C-enriched) methane in comparison to the lower maturated ethane of Triassic gas samples, suggesting a similar source and maturity for ethane and propane of Carboniferous gases, and a mixture of heavy ethane to the propane for Triassic gases. Based on the data plotted in the diagram of Chung et al. (1988), the residual kerogen from Silurian marine shale and palaeo oil reservoirs are the main source for Carboniferous gases, and that the residual kerogen from Silurian and Permian marine rocks and Permian paleao oil reservoirs constitute the principal source of Triassic gases.

Wang, Yunpeng; Zhao, Changyi; Wang, Hongjun; Wang, Zhaoyun; Wang, Zecheng

2013-03-01

58

Controlled confinement and release of gases in single-walled carbon nanotube bundles.  

PubMed

A simple procedure is described that locks small quantities of SF6, CO2, and 13CO2 into opened single-walled carbon nanotube (SWNT) bundles and keeps the gas in the SWNTs above the desorption temperature of these molecules. The technique involves opening the SWNTs with ozonolysis at 300 K followed by vacuum-annealing at 700 K. Gases are then cryogenically adsorbed into the opened SWNTs and locked into the SWNT pores by functionalizing the sample with a low-temperature ozone treatment. The low-temperature ozone treatment functionalizes the entry ports into the SWNT pores, which in turn create a physical barrier for gases trying to desorb through these functionalized ports. The samples are stable under vacuum for periods of at least 24 h, and the trapped gases can be released by vacuum-heating to 700 K. Reduced quantities of the trapped gases remain in the SWNTs even after exposure to room air. Fourier transform infrared spectroscopy is used to monitor the functionalities resulting from the ozone treatment and to detect the trapped gas species. PMID:16852100

Matranga, Christopher; Bockrath, Bradley

2005-05-19

59

Soluble species in the Arctic summer troposphere - acidic gases, aerosols, and precipitation  

SciTech Connect

The large-scale spatial distribution from 0.15-to 6 km altitude in the North American Arctic troposphere of several soluble acidic gases and major aerosol species during the summertime is reported. The distribution is found to be compositionally consistent on a large spatial scale. The summertime troposphere is an acidic environment, with HCOOH and CH3COOH the principal acidic gases while acidic sulfate aerosols dominate the particulate phase. There appears to be a surface source of NH3 over the pack ice which may originate from decay of dead marine organisms on the ice surface, evolution from surface ocean waters in open ice leads, or release from rotting sea ice. At low altitude over the pack ice this NH34 appears to partially neutralize aerosol acidity. Over sub-Arctic tundra in southeastern Alaska, inputs of marine biogenic sulfur from the Bering Sea appear to be an important source of boundary layer aerosol SO4(2-). The rainwater acidity over the tundra is typical of remote regions. 61 refs.

Talbot, R.W.; Vijgen, A.S.; Harriss, R.C. (New Hampshire Univ., Durham (United States) Old Dominion Univ., Norfolk, VA (United States))

1992-10-01

60

Control of Effluent Gases from Solid Waste Processing using Impregnated Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

One of the major problems associated with solid waste processing technologies is effluent contaminants that are released in gaseous forms from the processes. This is a concern in both biological as well as physicochemical solid waste processing. Carbon dioxide (CO2), the major gas released, does not present a serious problem and there are currently in place a number of flight-qualified technologies for CO2 removal. However, a number of other gases, in particular NOx, SO2, NH3, and various hydrocarbons (e.g. CH4) do present health hazards to the crew members in space habitats. In the present configuration of solid waste processing in the International Space Station (ISS), some of these gases are removed by the Trace Contaminant Control System (TCCS), demands a major resupply. Reduction of the resupply can be effective by using catalyst impregnated carbon nanotubes. For example, NO decomposition to N2 and O2 is thermodynamically favored. Data showing decomposition of NO on metal impregnated carbon nanotubes is presented. Comparisons are made of the existing TCCS systems with the carbon nanotube based technology for removing NOx based on mass/energy penalties.

Li, Jing; Fisher, John; Wignarajah, Kanapathipillai

2005-01-01

61

High emissions of carbon gases from a boreal headwater stream network of Interior Alaska  

NASA Astrophysics Data System (ADS)

Small boreal streams integrate the signals of terrestrial and aquatic carbon cycling in their catchments. Recent evidence suggests that despite their limited coverage on the landscape, small streams play a significant role in the downstream delivery of carbon and the emission of trace carbon gases (methane and carbon dioxide) to the atmosphere. However, aquatic gas emissions have not been well documented in many parts of the boreal forest including interior Alaska. We measured carbon gas emissions from a headwater stream network in the Beaver Creek watershed, Yukon River basin, during May (spring thaw) to September, 2011 using discrete measurements and continuous monitoring of stream pCO2. Carbon dioxide emissions from all sites averaged >4.5 gC m-2 day-1, with small streams exhibiting the highest and most variable emission rates. All sites were supersaturated with CO2 for the entire open-water season. Methane emissions averaged >9.1 mgC m-2 day-1 with a maximum of ~37 mgC m-2 day-1 in a mostly burned catchment. Low water temperatures and short water residence times probably limit in-stream respiration and support the hypothesis that high pCO2 in these streams is derived from terrestrial respiration and groundwater sources. Lower pCO2 of larger streams is likely controlled by rapid outgassing in upstream reaches and poor hydrologic connectivity with portions of the surrounding landscape. Overall, these small upland streams are a constant source of trace gases to the atmosphere during the ice free season and exhibit much higher emission rates than most previously studied boreal stream networks. This reinforces the need for more complete characterization of the spatial and temporal patterns of stream C-gas emissions when assessing whole watershed carbon budgets.

Crawford, J. T.; Striegl, R. G.; Wickland, K. P.; Stanley, E. H.

2011-12-01

62

Automatic carbon dioxide-methane gas sensor based on the solubility of gases in water.  

PubMed

Biogas methane content is a relevant variable in anaerobic digestion processing where knowledge of process kinetics or an early indicator of digester failure is needed. The contribution of this work is the development of a novel, simple and low cost automatic carbon dioxide-methane gas sensor based on the solubility of gases in water as the precursor of a sensor for biogas quality monitoring. The device described in this work was used for determining the composition of binary mixtures, such as carbon dioxide-methane, in the range of 0-100%. The design and implementation of a digital signal processor and control system into a low-cost Field Programmable Gate Array (FPGA) platform has permitted the successful application of data acquisition, data distribution and digital data processing, making the construction of a standalone carbon dioxide-methane gas sensor possible. PMID:23112626

Cadena-Pereda, Raúl O; Rivera-Muñoz, Eric M; Herrera-Ruiz, Gilberto; Gomez-Melendez, Domingo J; Anaya-Rivera, Ely K

2012-01-01

63

Utilization of carbon dioxide in industrial flue gases for the cultivation of microalga Chlorella sp.  

PubMed

The biomass and lipid productivity of Chlorella sp. MTF-15 cultivated using aeration with flue gases from a coke oven, hot stove or power plant in a steel plant of the China Steel Corporation in Taiwan were investigated. Using the flue gas from the coke oven, hot stove or power plant for cultivation, the microalgal strain obtained a maximum specific growth rate and lipid production of (0.827 d(-1), 0.688 g L(-1)), (0.762 d(-1), 0.961 g L(-1)), and (0.728 d(-1), 0.792 g L(-1)), respectively. This study demonstrated that Chlorella sp. MTF-15 could efficiently utilize the CO?, NOX and SO? present in the different flue gases. The results also showed that the growth potential, lipid production and fatty acid composition of the microalgal strain were dependent on the composition of the flue gas and on the operating strategy deployed. PMID:24950094

Kao, Chien-Ya; Chen, Tsai-Yu; Chang, Yu-Bin; Chiu, Tzai-Wen; Lin, Hsiun-Yu; Chen, Chun-Da; Chang, Jo-Shu; Lin, Chih-Sheng

2014-08-01

64

Selection of Arteries for Blood Sampling and Evaluation of Blood Gases and AcidBase Balance in Cattle  

Microsoft Academic Search

Nagy O., G. Kováã, H. Seidel, I. Paulíková:Selection of Arteries for Blood Sampling and Evaluation of Blood Gases and Acid-Base Balance in Cattle. Acta Vet. Brno 2002, 71: 289-296. The aim of this work was to select the most useful arteries for blood sampling in calves and cows in relation to the evaluation of acid-base balance and blood gases in

O. NAGY; H. SEIDEL; I. PAULÍKOVÁ

2002-01-01

65

Impact of carbon dioxide, trace gases, and climate change on global agriculture  

SciTech Connect

Global climate change is one of several important issues that will command the attention of policymakers and scientist in the 1990s. The evidence that concentrations of carbon dioxide (CO{sub 2}), and other gases are increasing in the atmosphere is irrefutable. The evidence, and the knowledge that CO{sub 2} and trace gases may absorb thermal radiation sufficient to warm the atmosphere, has prompted much speculation that ensuing atmospheric warming may lead to changes in the distribution of precipitation, and of crop adaptation and productivity, that would alter the world supply of food and fiber. The implications of this speculation are compelling for agronomists, because agronomists are stewards of the world's food supply and of the natural resources that are used to produce food. Agronomists have a pivotal role in conducting the research needed to anticipate crop response to climate changes, and in informing policymakers and the general public about the adequacy of our knowledge. In this publication agronomists assess the current status of scientific knowledge about the putative role of greenhouse gases in global climate change and report their findings.

Not Available

1990-01-01

66

Laboratory simulation of meteoritic noble gases. III - Sorption of neon, argon, krypton, and xenon on carbon - Elemental fractionation  

NASA Technical Reports Server (NTRS)

The sorption of Ne, Ar, Kr, and Xe was studied in carbon black, acridine carbon, and diamond in an attempt to understand the origin of trapped noble gases in meteorites. The results support a model in which gases are physically adsorbed on interior surfaces formed by a pore labyrinth within amorphous carbons. The data show that: (1) the adsorption/desorption times are controlled by choke points that restrict the movement of noble gas atoms within the pore labyrinth, and (2) the physical adsorption controls the temperature behavior and elemental fractionation patterns.

Wacker, John F.

1989-01-01

67

Analysis of Effluent Gases During the CCVD Growth of Multi Wall Carbon Nanotubes from Acetylene  

NASA Technical Reports Server (NTRS)

Catalytic chemical vapor deposition was used to grow multi-walled carbon nanotubes on a Fe:Co:CaCO3 catalyst from acetylene. The influent and effluent gases were analyzed by gas chromatography and mass spectrometry at different time intervals during the nanotubes growth process in order to better understand and optimize the overall reaction. A large number of byproducts were identified and it was found that the number and the level for some of the carbon byproducts significantly increased over time. The CaCO3 catalytic support thermally decomposed into CaO and CO2 resulting in a mixture of two catalysts for growing the nanotubes, which were found to have outer diameters belonging to two main groups 8 to 35 nm and 40 to 60 nm, respectively.

Schmitt, T. C.; Biris, A. S.; Miller, D. W.; Biris, A. R.; Lupu, D.; Trigwell, S.; Rahman, Z. U.

2005-01-01

68

Laboratory simulation of meteoritic noble gases. I - Sorption of xenon on carbon: Trapping experiments  

NASA Technical Reports Server (NTRS)

The sorption of Xe-127 at 5 x 10 to the -7th atm onto carbon black, pyrolyzed polyvinylidene chloride, and pyrolyzed acridine at 100-1000 C for 5 min-240 h is measured experimentally by gamma spectrometry. The results are presented in tables and graphs and characterized in detail. The tightly bound Xe remaining in the samples after 4000 min pumping at temperatures above 100 C is found to comprise two components: a low-temperature component attributed to physisorption within an atomic-scale labyrinth of micropores, and a high-temperature component due to volume diffusion. The implications for the trapping of noble gases near grain surfaces of amorphous carbon in meteorites are considered.

Wacker, J. F.; Zadnik, M. G.; Anders, E.

1985-01-01

69

Molecular dynamics simulation of diffusion of gases in a carbon-nanotube-polymer composite  

SciTech Connect

Extensive molecular dynamics (MD) simulations were carried out to compute the solubilities and self-diffusivities of CO{sub 2} and CH{sub 4} in amorphous polyetherimide (PEI) and mixed-matrix PEI generated by inserting single-walled carbon nanotubes into the polymer. Atomistic models of PEI and its composites were generated using energy minimizations, MD simulations, and the polymer-consistent force field. Two types of polymer composite were generated by inserting (7,0) and (12,0) zigzag carbon nanotubes into the PEI structure. The morphologies of PEI and its composites were characterized by their densities, radial distribution functions, and the accessible free volumes, which were computed with probe molecules of different sizes. The distributions of the cavity volumes were computed using the Voronoi tessellation method. The computed self-diffusivities of the gases in the polymer composites are much larger than those in pure PEI. We find, however, that the increase is not due to diffusion of the gases through the nanotubes which have smooth energy surfaces and, therefore, provide fast transport paths. Instead, the MD simulations indicate a squeezing effect of the nanotubes on the polymer matrix that changes the composite polymers' free-volume distributions and makes them more sharply peaked. The presence of nanotubes also creates several cavities with large volumes that give rise to larger diffusivities in the polymer composites. This effect is due to the repulsive interactions between the polymer and the nanotubes. The solubilities of the gases in the polymer composites are also larger than those in pure PEI, hence indicating larger gas permeabilities for mixed-matrix PEI than PEI itself.

Lim, Seong Y.; Sahimi, Muhammad; Tsotsis, Theodore T.; Kim, Nayong [Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-1211 (United States)

2007-07-15

70

Synergistic effect of Br?nsted acid and platinum on purification of automobile exhaust gases  

PubMed Central

The catalytic purification of automobile exhaust gases (CO, NOx and hydrocarbons) is one of the most practiced conversion processes used to lower the emissions and to reduce the air pollution. Nevertheless, the good performance of exhaust gas purification catalysts often requires the high consumption of noble metals such as platinum. Here we report that the Brønsted acid sites on the external surface of a microporous silicoaluminophosphate (SAPO) act as a promoter for exhaust gas purification, effectively cutting the loading amount of platinum in the catalyst without sacrifice of performance. It is revealed that in the Pt-loaded SAPO-CHA catalyst, there exists a remarkable synergistic effect between the Brønsted acid sites and the Pt nanoparticles, the former helping to adsorb and activate the hydrocarbon molecules for NO reduction during the catalytic process. The thermal stability of SAPO-CHA also makes the composite catalyst stable and reusable without activity decay. PMID:23907148

Fu, Wei; Li, Xin-Hao; Bao, Hong-Liang; Wang, Kai-Xue; Wei, Xiao; Cai, Yi-Yu; Chen, Jie-Sheng

2013-01-01

71

Combustion systems and power plants incorporating parallel carbon dioxide capture and sweep-based membrane separation units to remove carbon dioxide from combustion gases  

DOEpatents

Disclosed herein are combustion systems and power plants that incorporate sweep-based membrane separation units to remove carbon dioxide from combustion gases. In its most basic embodiment, the invention is a combustion system that includes three discrete units: a combustion unit, a carbon dioxide capture unit, and a sweep-based membrane separation unit. In a preferred embodiment, the invention is a power plant including a combustion unit, a power generation system, a carbon dioxide capture unit, and a sweep-based membrane separation unit. In both of these embodiments, the carbon dioxide capture unit and the sweep-based membrane separation unit are configured to be operated in parallel, by which we mean that each unit is adapted to receive exhaust gases from the combustion unit without such gases first passing through the other unit.

Wijmans, Johannes G. (Menlo Park, CA); Merkel, Timothy C (Menlo Park, CA); Baker, Richard W. (Palo Alto, CA)

2011-10-11

72

Carbon dioxide separation from flue gases: a technological review emphasizing reduction in greenhouse gas emissions.  

PubMed

Increasing concentrations of greenhouse gases (GHGs) such as CO2 in the atmosphere is a global warming. Human activities are a major cause of increased CO2 concentration in atmosphere, as in recent decade, two-third of greenhouse effect was caused by human activities. Carbon capture and storage (CCS) is a major strategy that can be used to reduce GHGs emission. There are three methods for CCS: pre-combustion capture, oxy-fuel process, and post-combustion capture. Among them, post-combustion capture is the most important one because it offers flexibility and it can be easily added to the operational units. Various technologies are used for CO2 capture, some of them include: absorption, adsorption, cryogenic distillation, and membrane separation. In this paper, various technologies for post-combustion are compared and the best condition for using each technology is identified. PMID:24696663

Songolzadeh, Mohammad; Soleimani, Mansooreh; Takht Ravanchi, Maryam; Songolzadeh, Reza

2014-01-01

73

Foliage plants for indoor removal of the primary combustion gases carbon monoxide and nitrogen dioxide  

NASA Technical Reports Server (NTRS)

Foliage plants were evaluated for their ability to sorb carbon monoxide and nitrogen dioxide, the two primary gases produced during the combustion of fossil fuels and tobacco. The spider plant (Chlorophytum elatum var. vittatum) could sorb 2.86 micrograms CO/sq cm leaf surface in a 6 h photoperiod. The golden pothos (Scindapsus aureus) sorbed 0.98 micrograms CO/sq cm leaf surface in the same time period. In a system with the spider plant, greater than or equal to 99 percent of an initial concentration of 47 ppm NO2 could be removed in 6 h from a void volume of approximately 0.35 cu m. One spider plant potted in a 3.8 liter container can sorb 3300 micrograms CO and effect the removal of 8500 micrograms NO2/hour, recognizing the fact that a significant fraction of NO2 at high concentrations will be lost by surface sorption, dissolving in moisture, etc.

Wolverton, B. C.; Mcdonald, R. C.; Mesick, H. H.

1985-01-01

74

Carbon 40 (2002) 12491254 Oxidation protection of carbon materials by acid phosphate  

E-print Network

been used to im-3 [26] and boric acid [27,28]. Immersion in the solution is pregnate carbonsCarbon 40 (2002) 1249­1254 Oxidation protection of carbon materials by acid phosphate impregnation Abstract Acid phosphate impregnation, with ozone pre-treatment, improves the oxidation resistance of carbon

Chung, Deborah D.L.

75

Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases, Fiscal Year 2002 Annual Report  

SciTech Connect

The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has, since its inception in 1982, enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change, including atmospheric concentrations and atmospheric emissions of carbon dioxide (CO{sub 2}) and other radiatively active gases; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea levels.

Cushman, R.M.

2003-08-28

76

PREDICTING TEMPERATURE BEHAVIOR IN CARBONATE ACIDIZING TREATMENTS  

E-print Network

in a multilayer carbonate formation and if the low-permeability layer is treated well. This work develops a numerical model to determine the temperature behavior for both injection and flow-back situations. An important phenomenon in this process... wormholes will be created. 4 1.3 Importance We develop a numerical model to determine the temperature profile for both injection and flow back process in an acid stimulation. The method used here is similar as the one presented by previous works...

Tan, Xuehao

2010-01-16

77

Carbon dioxide Information Analysis Center and World Data Center: A for Atmospheric trace gases. Annual progress report, FY 1994  

SciTech Connect

This report summarizes the activities and accomplishments made by the Carbon Dioxide Information Analysis Center and World Data Center-A for Atmospheric Trace Gases during the fiscal year 1994. Topics discussed in this report include; organization and staff, user services, systems, communications, Collaborative efforts with China, networking, ocean data and activities of the World Data Center-A.

Burtis, M.D. [comp.] [Tennessee Univ., Knoxville, TN (United States). Energy, Environment and Resources Center; Cushman, R.M.; Boden, T.A.; Jones, S.B.; Nelson, T.R.; Stoss, F.W. [Oak Ridge National Lab., TN (United States)

1995-03-01

78

Wind tunnel experiments on the retention of trace gases during riming: nitric acid, hydrochloric acid, and hydrogen peroxide  

NASA Astrophysics Data System (ADS)

Laboratory experiments were carried out in a vertical wind tunnel to study the retention of different atmospheric trace gases during riming. In the experiments, the rimed ice particles floated in a laminar air stream carrying a cloud of supercooled droplets with radii between 10 and 20 ?m. Ice particles, dendritic ice crystals, and snow flakes with diameters between 6 mm and 1.5 cm were allowed to rime at temperatures between -5 and -12 °C where riming mainly proceeds in the atmosphere and with cloud liquid water contents between 1 and 1.5 g m-3 which are values typically found in atmospheric mixed-phase clouds. Three trace species were investigated, nitric and hydrochloric acid, and hydrogen peroxide. They were present in the supercooled liquid droplets in concentrations from 1 to 120 ppmv, i.e. similar to the concentrations measured in cloud drops. The chemical analyses of the rimed ice particles allow one to determine the trace species concentration in the ice phase. Together with the known liquid phase concentration the retention coefficients were calculated in terms of the amount of the species which remained in the ice phase after freezing. It was found that the highly soluble trace gases, nitric and hydrochloric acid, were retained nearly completely (98.6±8% and 99.7±9%, respectively) while for hydrogen peroxide a retention of 64.3±11% was determined. No influence of the riming temperature on the retention was found which can be explained by the fact that in the observed range of temperature and liquid water content, riming proceeded in the dry growth regime.

von Blohn, N.; Diehl, K.; Mitra, S. K.; Borrmann, S.

2011-11-01

79

Wind tunnel experiments on the retention of trace gases during riming: nitric acid, hydrochloric acid, and hydrogen peroxide  

NASA Astrophysics Data System (ADS)

Laboratory experiments were carried out in a vertical wind tunnel to study the retention of different atmospheric trace gases during riming. In the experiments, the rimed ice particles floated in a laminar air stream carrying a cloud of supercooled droplets with radii between 10 and 20 ?m. Ice particles, dendritic ice crystals, and snow flakes with diameters between 6 mm and 1.5 cm were allowed to rime at temperatures between -5 and -12 °C where riming mainly proceeds in the atmosphere and with cloud liquid water contents between 1 and 1.5 g m-3 which are values typically found in atmospheric mixed phase clouds. Three trace species were investigated, nitric and hydrochloric acid, and hydrogen peroxide. They were present in the supercooled liquid droplets in concentrations from 1 to 120 ppmv, i.e. similar to the ones measured in cloud drops. The chemical analyses of the rimed ice particles allow to determine the trace species concentration in the ice phase. Together with the known liquid phase concentration the retention coefficients were calculated in terms of the amount of the species which remained in the ice phase after freezing. It was found that the highly soluble trace gases nitric and hydrochloric acid were retained nearly completely (98.6 ± 8 % and 99.7 ± 9 %, respectively) while for hydrogen peroxide a retention coefficient of 64.3 ± 11 % was determined. No influence of the riming temperature on the retention was found which can be explained by the fact that in the observed range of temperature and liquid water content riming proceeded in the dry growth regime.

von Blohn, N.; Diehl, K.; Mitra, S. K.; Borrmann, S.

2011-06-01

80

Implications of light absorbing organic aerosol - “brown carbon” - on satellite retrievals of atmospheric trace gases  

NASA Astrophysics Data System (ADS)

Satellite instruments like GOME, GOME-2, SCIAMACHY and OMI, measure backscattered solar radiation to retrieve atmospheric trace gas columns. In order to quantify these columns, Radiative Transfer (RT) computations of Air Mass Factors (AMFs) are needed to account for radiation scattering and absorption processes. Any RT modeling requires a priori information on the state of the atmosphere such as trace gas/aerosol vertical profiles and aerosol properties (e.g. size parameter and Single Scattering Albedo (SSA)). This a priori input is crucial for the correct quantification of the measured trace gas columns. Recent field studies of urban aerosol show that the Organic Carbon (OC) component contributes highly to the absorption of short wave incoming solar radiation. This leads to measured Single Scattering Albedo (SSA) values as low as 0.78 below 420 nm. Here, the effect of SSA on retrieved AMFs over organic aerosol hotspots, e.g. the urban polluted boundary layer and biomass burning plumes is studied. It is demonstrated that over such hotspots trace gas columns can be underestimated up to a factor of three when neglecting the additional light absorption by OC aerosol. This applies to all trace gases that absorb light at wavelengths shorter than 420 nm, such as HCHO, SO2, BrO, HONO and possibly NO2, if evaluated below 420 nm. The sensitive coupling between trace gas retrievals and OA optical properties that we quantify here also means that any trends in OA optical properties can cause artificial trends in trace gas retrievals; decoupling of both trends requires additional information about the variability of OA optical properties to avoid bias in the long-term trends in trace-gases.

Dix, B. K.; Volkamer, R.

2009-12-01

81

Carbon emission limits required to satisfy future representative concentration pathways of greenhouse gases  

NASA Astrophysics Data System (ADS)

The response of the second-generation Canadian earth system model (CanESM2) to historical (1850-2005) and future (2006-2100) natural and anthropogenic forcing is assessed using the newly-developed representative concentration pathways (RCPs) of greenhouse gases (GHGs) and aerosols. Allowable emissions required to achieve the future atmospheric CO2 concentration pathways, are reported for the RCP 2.6, 4.5 and 8.5 scenarios. For the historical 1850-2005 period, cumulative land plus ocean carbon uptake and, consequently, cumulative diagnosed emissions compare well with observation-based estimates. The simulated historical carbon uptake is somewhat weaker for the ocean and stronger for the land relative to their observation-based estimates. The simulated historical warming of 0.9°C compares well with the observation-based estimate of 0.76 ± 0.19°C. The RCP 2.6, 4.5 and 8.5 scenarios respectively yield warmings of 1.4, 2.3, and 4.9°C and cumulative diagnosed fossil fuel emissions of 182, 643 and 1617 Pg C over the 2006-2100 period. The simulated warming of 2.3°C over the 1850-2100 period in the RCP 2.6 scenario, with the lowest concentration of GHGs, is slightly larger than the 2°C warming target set to avoid dangerous climate change by the 2009 UN Copenhagen Accord. The results of this study suggest that limiting warming to roughly 2°C by the end of this century is unlikely since it requires an immediate ramp down of emissions followed by ongoing carbon sequestration in the second half of this century.

Arora, V. K.; Scinocca, J. F.; Boer, G. J.; Christian, J. R.; Denman, K. L.; Flato, G. M.; Kharin, V. V.; Lee, W. G.; Merryfield, W. J.

2011-03-01

82

Emission characteristics and control efficiency of acidic and basic gases and aerosols from packed towers  

NASA Astrophysics Data System (ADS)

Large amount of acidic liquids, such as H 2SO 4, HF, HCl and HNO 3, and basic NH 3 liquid are used in high-tech industries in cleaning and etching processes in the Hsinchu Science-Based Industrial Park in Taiwan. The industries use packed towers (or scrubbers) to control emission of these inorganic pollutants, in which acidic gases but not particles are regulated by the Taiwan EPA's strict emission standard for semiconductor industry. To understand whether the emission standard is met and to investigate the emission rates, emission profiles, emission factors, and control efficiencies of various gaseous/aerosol species, measurement of pollutants before and after the packed towers was conducted using a sensitive porous metal sampler during January 2001 to February 2003. Results show that the pollutants are mainly in the gaseous phase, and the control efficiency of pollutants is low and variable when the inlet concentration is low. In addition to the control efficiency data, emission factors before the control device for various gas and particle species have also been developed for estimating the emission rates.

Tsai, Chuen-Jinn; Chang, Chang-Tso; Liu, Tsing-Wei; Huang, Chun-Chao; Chien, Chih-Liang; Chein, Hung Min

83

Distribution of PM 2.5, acidic and basic gases near highway in central Taiwan  

NASA Astrophysics Data System (ADS)

Particulate PM 2.5 and acidic gas samples were collected during two successive sampling periods at two different sampling sites namely, Nantou (near highway site) and Erlin (far highway site) of central Taiwan region. The distribution of PM 2.5, acidic and basic gases was assessed simultaneously in both the sampling sites using annual denuder system. Chemical species of PM 2.5 analyzed included NO 3-, SO 42-, NH 4+, Cl -, Ca 2+, K + and Na + and gaseous HNO 2, HNO 3, HCl, SO 2 and NH 3. Data on NO, NO 2, CO and meteorological parameters were obtained from air quality monitoring station, Environmental Protection Agency (EPA), Taiwan. Time-weighted mean concentration model was used to investigate the pollutant sources. In addition, formation of nitrate aerosols from NO 2 was discussed. The PM 2.5 concentrations were 41.1 and 32.9 ?g m - 3 at near and far highway sites respectively. The average concentration of three main ionic species SO 42-, NO 3- and NH 4+ accounted to 44% for PM 2.5 indicating that the formation was mainly via secondary process. The PM 2.5, HNO 3, NO 3-, NO, NO 2 and CO were highest at near highway site compared to far highway site. Based on the results of this study we conclude that, higher traffic emissions coupled with poor ventilation due to topography of the area caused increased HNO 3, NO 3-, NO, NO 2 and CO concentrations in near highway site.

Horng, Chuen-Liang; Cheng, Man-Ting

2008-04-01

84

The Role of Carbon Management Technologies in Addressing Atmospheric Stabilization of Greenhouse Gases  

SciTech Connect

Recent progress in decarbonization processes and engineered storage systems for CO2, together with preliminary cost estimates for these technologies, indicate that capture and storage of CO2 will have a major role to play in achieving deep reductions in emissions. These technologies hold the potential to reduce the cost of stabilizing the concentration of greenhouse gases, the ultimate objective of the UN Framework Convention on Climate Change (FCCC). Their value rises as the allowable level of cumulative carbon emissions declines. The value of these technologies is robust regardless of whether the world's economically recoverable oil and gas resources are eventually found to be large or small. This paper considers the economic implication of those advances in the context of long-term, global climate change mitigation strategies. This indicates the need for a broad, robust research and development strategy to reduce the cost of separating CO2 and to make accessible the widest range of storage reservoirs. It is also important to demonstrate excellent security of storage, in order to win public acceptance of the use of capture and storage techniques.

Edmonds, James A. (BATTELLE (PACIFIC NW LAB)); Freund, Paul F. (WASTE MANAGEMENT); Dooley, James J. (BATTELLE (PACIFIC NW LAB)); David Williams, Bob Durie, et. al.

2002-08-10

85

Detection of a CO and NH3 gas mixture using carboxylic acid-functionalized single-walled carbon nanotubes  

PubMed Central

Carbon nanotubes (CNT) are extremely sensitive to environmental gases. However, detection of mixture gas is still a challenge. Here, we report that 10 ppm of carbon monoxide (CO) and ammonia (NH3) can be electrically detected using a carboxylic acid-functionalized single-walled carbon nanotubes (C-SWCNT). CO and NH3 gases were mixed carefully with the same concentrations of 10 ppm. Our sensor showed faster response to the CO gas than the NH3 gas. The sensing properties and effect of carboxylic acid group were demonstrated, and C-SWCNT sensors with good repeatability and fast responses over a range of concentrations may be used as a simple and effective detection method of CO and NH3 mixture gas. PMID:23286690

2013-01-01

86

STABILITY EVALUATION OF SULFUR DIOXIDE, NITRIC OXIDE AND CARBON MONOXIDE GASES IN CYLINDERS  

EPA Science Inventory

The US EPA recommends in their EPA Traceability Protocol 1 and 2 that reactive gases be reanalyzed every six months. The purpose of this study was to assess the stability of selected reactive gases as a function of time to determine the feasibility of extending the recertificatio...

87

The Perils of Carbonic Acid and Equilibrium Constants.  

ERIC Educational Resources Information Center

Discusses the effects caused by small amounts of carbon dioxide usually present in water and acid-base equilibria of dilute solutions. Notes that dilute solutions of most weak acids and bases undergo significant dissociation or protonation. (MVL)

Jencks, William P.; Altura, Rachel A.

1988-01-01

88

Low to middle tropospheric profiles and biosphere/troposphere fluxes of acidic gases in the summertime Canadian taiga  

NASA Technical Reports Server (NTRS)

We report features of acidic gases in the troposphere from 9 to 5000 m altitude above ground over the Canadian taiga in the summer of 1990. The measurements were conducted at a 30-m meteorological tower and from the NASA Wallops Electra aircraft as part of the joint U.S.-Canadian Arctic Boundary Layer Expedition (ABLE) 3B Northern Wetland Studies (NOWES). We sampled air for acidic gases using the mist chamber collector coupled with subsequent analysis using ion chromatography. At the tower we collected samples at two heights during a 13-day period, including diurnal studies. Using eddy flux and profile data, we estimated the biosphere/troposphere fluxes of nitric, formic, and acetic acids and sulfur dioxide. For the organic acids, emissions from the taiga in the afternoon hours and deposition during the predawn morning hours were observed. The flux intensities alone were however not high enough to explain the observed changes in mixing ratios. The measured deposition fluxes of nitric acid were high enough to have a significant influence on its mixing ratio in the boundary layer. On three days we measured vertical profiles of nitric, formic, and acetic acids through the lower to midtroposphere. We found that the chemical composition of the troposphere was extremely heterogenous. Pronounced layers of polluted air were readily apparent from our measurements. Local photochemical production and episodic long-range transport of trace components, originating from biomass burning and possibly industrial emissions, appear to have a strong influence on the composition of the troposphere and biosphere/troposphere fluxes of acidic gases at this site.

Klemm, O.; Talbot, R. W.; Fitzgerald, D. R.; Klemm, K. I.; Lefer, B. L.

1994-01-01

89

The air we breathe: three vital respiratory gases and the red blood cell: oxygen, nitric oxide, and carbon dioxide.  

PubMed

Three vital respiratory gases-oxygen (O(2)), nitric oxide (NO), and carbon dioxide (CO(2))-intersect at the level of the human red blood cell (RBC). In addition to hemoglobin (Hb)'s central role in O(2) transport, interaction of Hb with the Band 3 metabolon balances RBC energy flow. 2,3-Diphosphoglycerate enhances O(2) transport across the placenta and plays an important role in regulating RBC plasticity. NO is a key mediator of hypoxic vasodilation, but the precise role of RBC Hb remains controversial. In addition to established theories that depend on RBC uptake, delivery, and discharge of NO or its metabolites, an alternative hypothesis based on RBC permeability is suggested. NO depletion by free Hb may account for several clinical features seen during intravascular hemolysis or during deliberate infusion of Hb solutions used as RBC substitutes. CO(2) released by tissues triggers oxygen release through a series of well-coordinated reactions centered on the Band 3 metabolon. While RBC carbonic anhydrase and the Band 3 anion exchanger are central to this process, there is surprisingly little research on the kinetics of CO(2) clearance by transfusion. The three RBC gases are directly related to the three principal gases of Earth's atmosphere. Human fossil fuel consumption dumps 90 million metric tons of carbon into the atmosphere annually. Increasing CO(2) levels are linked to global warming, melting Arctic ice, rising sea levels, and climate instability. Just as individual cells depend on balance of the three vital gases, so too will their balance determine survival of life on Earth. PMID:21496039

Dzik, Walter H

2011-04-01

90

Citric acid cycle biomimic on a carbon electrode  

Microsoft Academic Search

The citric acid cycle is one of the main metabolic pathways living cells utilize to completely oxidize biofuels to carbon dioxide and water. The overall goal of this research is to mimic the citric acid cycle at the carbon surface of an electrode in order to achieve complete oxidation of ethanol at a bioanode to increase biofuel cell energy density.

Daria Sokic-Lazic; Shelley D. Minteer

2008-01-01

91

Influence of sulfuric acid impregnation on the carbonization of cellulose  

NASA Astrophysics Data System (ADS)

That cellulose, as source of carbon materials, has a low char yield in pyrolysis can present serious difficulties. In this study, we focused on the effect of using sulfuric acid as a dehydration agent and examined the pyrolytic behavior of cellulose impregnated with sulfuric acid by using thermogravimetry and scanning electron microscopy. The mass yield of carbon after an 800 °C treatment in nitrogen was increased by 2-5 times with the addition of small amounts of sulfuric acid. Sample shrinkage during carbonization was also significantly reduced. These effects are interpreted as being the result of facilitated extraction of water from cellulose accompanied by development of extended carbon networks.

Kang, Kyu-Young; Kim, Dae-Young

2012-05-01

92

Dissociation constants for carbonic acid determined from field measurements  

Microsoft Academic Search

A number of workers have recently shown that the thermodynamic constants for the dissociation of carbonic acid in seawater of Mehrbach et al. are more reliable than measurements made on artificial seawater. These studies have largely been confined to looking at the internal consistency of measurements of total alkalinity (TA), total inorganic carbon dioxide (TCO2) and the fugacity of carbon

Frank J. Millero; Denis Pierrot; Kitack Lee; Rik Wanninkhof; Richard Feely; Christopher L. Sabine; Robert M. Key; Taro Takahashi

2002-01-01

93

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

EPA Science Inventory

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

94

Influence of the thermodynamic constants of carbonic acid in the current views of the ocean carbon cycle  

SciTech Connect

The recent redetermination of the thermodynamic dissociation constants of carbonic acid (K*[sub 1] and K[sup asterisk][sub 2]) in sea water (Goyet and Poisson; in press), appears to have uncovered some fundamental issues concerning the determination of the parameter of the CO[sub 2]/carbonate system. We use a non-linear curve-fitting procedure to illustrate the importance of small differences in pK*[sub 1] (which generate large errors in the fit of the thermodynamical model to the first points of the curve) in the determination of total alkalinity (TA) and total CO[sub 2] (TCO[sub 2]) from an experimental potentiometric titration curve. This flexible procedure which may also take into account concentrations of unknown protolytes shows that presently the accuracy for titration TA and TCO[sub 2] are [+-] 0.1 [mu]eq.kp[sup -1] and [+-] 0.6 [mu]M.kg[sup -1], respectively. We review the effect this has on the determination of oceanic properties such as CO[sup 2-][sub 3], and possible interfering organic species. This paper also reports the practical implications involved by the improvement of the determination of the dissociation constants of carbonic acid in numerical models used to study the effect of rising carbon dioxide (the most important of the greenhouse gases).

Goyet, C.; Bradshaw, A.L.; Brewer, P.G. (Woods Hole Oceanographic Inst., MA (United States))

1990-01-09

95

Comparative Climate Responses of Anthropogenic Greenhouse Gases, All Major Aerosol Components, Black Carbon, and Methane, Accounting for the Evolution of the Aerosol Mixing State and of Clouds/Precipitation from Multiple Aerosol Size Distributions  

NASA Astrophysics Data System (ADS)

Several modeling studies to date have simulated the global climate response of anthropogenic greenhouse gases and bulk (non-size-resolved) sulfate or generic aerosol particles together, but no study has examined the climate response of greenhouse gases simultaneously with all major size- and composition resolved aerosol particle components. Such a study is important for improving our understanding of the effects of anthropogenic pollutants on climate. Here, the GATOR-GCMOM model is used to study the global climate response of (a) all major greenhouse gases and size-resolved aerosol components, (b) all major greenhouse gases alone, (c) fossil-fuel soot (black carbon, primary organic matter, sulfuric acid, bisulfate, sulfate), and (d) methane. Aerosol components treated in all simulations included water, black carbon, primary organic carbon, secondary organic carbon, sulfuric acid, bisulfate, sulfate, nitrate, chloride, ammonium, sodium, hydrogen ion, soil dust, and pollen/spores. Fossil-fuel soot (FFS) was emitted into its own size distribution. All other components, including biofuel and biomass soot, sea-spray, soil dust, etc., were emitted into a second distribution (MIX). The FFS distribution grew by condensation of secondary organic matter and sulfuric acid, hydration of water, and dissolution of nitric acid, ammonia, and hydrochloric acid. It self-coagulated and heterocoagulated with the MIX distribution, which also grew by condensation, hydration, and dissolution. Treatment of separate distributions for FFS allowed FFS to evolve from an external mixture to an internal mixture. In both distributions, black carbon was treated as a core component for optical calculations. Both aerosol distributions served as CCN during explicit size-resolved cloud formation. The resulting clouds grew by coagulation and condensation, coagulated with interstitial aerosol particles, and fell to the surface as rain and snow, carrying aerosol constituents with them. Thus, cloud evolution accounted for the first and second indirect effects and the mixing state of aerosol particles. The optical properties of clouds were found by treating black carbon inclusions surrounded by a shell of water. The albedos of snow, sea ice, and water were calculated with radiative transfer solutions, assuming black carbon inclusions in the case of snow and sea ice. The simulations accounted for 3-D energy diffusion to the deep ocean and 2-D ocean circulation. Major conclusions are (a) the most important constituents of global warming, in terms of climate response, appear to be, in order, carbon dioxide, black carbon, and methane, (b) aerosol particles (all together) appear to act on top of greenhouse gases to enhance extremes in both regional cooling and regional warming, (b) the combination of important greenhouse gases and aerosol particles can explain observed major regions of historic warming and cooling, and (d) eliminating all anthropogenic aerosol emission could more than double current global warming but would have less of an effect than independently doubling carbon dioxide.

Jacobson, M. Z.

2005-12-01

96

Removal potential of toxic 2378-substituted PCDD/F from incinerator flue gases by waste-derived activated carbons  

SciTech Connect

The application of activated carbons has become a commonly used emission control protocol for the removal or adsorption of persistent organic pollutants from the flue gas streams of waste incinerators. In this study, the 2378-substituted PCDD/F removal efficiency of three types of activated carbons derived from the pyrolysis of refuse derived fuel, textile waste and scrap tyre was investigated and compared with that of a commercial carbon. Experiments were carried out in a laboratory scale fixed-bed reactor under a simulated flue gas at 275 deg. C with a reaction period of four days. The PCDD/F in the solid matrices and exhaust gas, were analyzed using gas chromatography coupled with a triple quadrupole mass spectrometer. In the absence of activated carbon adsorbent, there was a significant increase in the concentration of toxic PCDD/F produced in the reacted flyash, reaching up to 6.6 times higher than in the raw flyash. In addition, there was a substantial release of PCDD/F into the gas phase, which was found in the flue gas trapping system. By application of the different commercial, refuse derived fuel, textile and tyre activated carbons the total PCDD/F toxic equivalent removal efficiencies in the exhaust gas stream were 58%, 57%, 64% and 52%, respectively. In general, the removal of the PCDDs was much higher with an average of 85% compared to PCDFs at 41%. Analysis of the reacted activated carbons showed that there was some formation of PCDD/F, for instance, a total of 60.6 {mu}g I-TEQ kg{sup -1} toxic PCDD/F was formed in the refuse derived fuel activated carbon compared to 34 {mu}g I-TEQ kg{sup -1} in the commercial activated carbon. The activated carbons derived from the pyrolysis of waste, therefore, showed good potential as a control material for PCDD/F emissions in waste incinerator flue gases.

Hajizadeh, Yaghoub; Onwudili, Jude A. [Energy and Resources Research Institute, University of Leeds, Leeds LS2 9JT (United Kingdom); Williams, Paul T., E-mail: p.t.williams@leeds.ac.uk [Energy and Resources Research Institute, University of Leeds, Leeds LS2 9JT (United Kingdom)

2011-06-15

97

Acid Rain  

NSDL National Science Digital Library

Due to the presence of dissolved gases such as carbon dioxide, rainfall is naturally acidic. The release of other gases and chemicals such as sulfur dioxide during the combustion of coal and oil can cause rainfall to become even more acidic, sometimes to the point of toxicity. In this activity, students will measure the pH of local rainfall to see what effect these gases have in their region. They will also check an online resource to see how the releases of acid rain-causing chemicals have varied over the past 20 years, and answer questions about the information they uncover.

Fox, Chris

98

Solubility selective membrane materials for carbon dioxide removal from mixtures with light gases  

NASA Astrophysics Data System (ADS)

Membrane technology has attracted interest for the selective removal of carbon dioxide from mixtures with light gases such as H2, CH4 and N2. While conventional structure-property correlations have focused mainly on improving the separation performance by increasing polymer size sieving ability (i.e., diffusivity selectivity), this project explores the possibility of harnessing favorable interactions between CO 2 and polymers containing polar groups to improve permeability/selectivity properties. Ether oxide groups are discovered to be among the best moieties known to interact with CO2, leading to high CO2 solubility and CO2/light gas solubility selectivity, while still providing polymer chain flexibility, leading to high CO2 diffusivity and favorable CO2/H2 diffusivity selectivity. Poly(ethylene oxide) (PEO) has a high concentration of ether oxygen groups and exhibits high CO2/light gas selectivities. However, gas permeability is low due to the high crystallinity in PEO. Crosslinking and introduction of short chain branching are efficient methods to inhibit crystallization. Three series of crosslinked poly(ethylene oxide) rubbers have been prepared using prepolymer solutions containing: (1) poly(ethylene glycol) diacrylate (PEGDA) and H2O, (2) PEGDA and poly(ethylene glycol) methyl ether acrylate (PEGMEA), and (3) PEGDA and poly(ethylene glycol) acrylate (PEGA). Independent of the prepolymer composition, all of these polymers have similar ethylene oxide (EO) content (approximately 82 wt.%). Crosslink density decreases with decreasing PEGDA content in the prepolymer solution, which is estimated from water swelling experiments and/or dynamic mechanical testing and has essentially no effect on gas transport properties. Increasing PEGMEA content increases the average size of free volume elements, resulting in a decreased glass transition temperature, and increased CO 2 permeability and CO2/H2 selectivity. In contrast, the presence of PEGA or water has a negligible impact on these properties. Due to the affinity between EO and CO2, decreasing temperature increases CO2/light gas solubility selectivity. PEGDA/PEGMEA-30 (a copolymer containing 30 wt.% PEGDA and the balance PEGMEA) demonstrates very favorable mixed gas CO2/H2 and CO2/CH 4 separation performance. The separation properties improve with decreasing temperature and have excellent resistance to impurities in the feed streams such as high pressure CO2, higher hydrocarbons and water. Interestingly, the highly sorbing impurities can even improve CO2/H2 separation. Pure and mixed gas diffusivity and permeability in these crosslinked PEO rubbers were successfully modeled using a new free volume model, which was based on the Cohen-Turnbull and Fujita free volume models coupled with Chow's model for estimating glass transition temperatures in polymer/gas mixtures as a function of temperature and penetrant concentration.

Lin, Haiqing

99

Meldrum's acids and 5-alkylidene Meldrum's acids in catalytic carbon-carbon bond-forming processes.  

PubMed

Meldrum's acid (2,2-dimethyl-1,3-dioxane-4,6-dione) is a molecule with a unique history, owing to its originally misassigned structure, as well as a unique place among acylating agents, owing to its high acidity and remarkable electrophilicity. In this Account, we outline the work of our group and others toward harnessing the reactivity of Meldrum's acid derivatives in catalytic C-C bond-forming reactions. Taking advantage of the ability of Meldrum's acid to decompose to CO(2) and acetone following acyl substitution, we have shown that intramolecular Friedel-Crafts acylations can be performed under mild Lewis acidic conditions to yield a variety of benzocyclic ketones. In a further expansion of this method, a domino Friedel-Crafts acylation/alpha-tert alkylation reaction was used to complete the first total synthesis of (+/-)-taiwaniaquinol B. The unique characteristics of Meldrum's acid extend to its alkylidene derivatives, which have also proven exceptionally useful for the development of new reactions not readily accessible from other unsaturated carbonyl electrophiles. By combining the electrophilicity and dienophilicity of alkylidene Meldrum's acid with our Friedel-Crafts chemistry, we have demonstrated new domino syntheses of coumarin derivatives and tetrahydrofluorenones by conjugate additions, Diels-Alder cycloadditions, and C-H functionalizations. Additionally, we have used these powerful acceptors to allow conjugate alkenylation with functionalized organostannanes, and conjugate allylation under very mild conditions. We have also shown that these molecules permit the asymmetric formation of all-carbon quaternary stereocenters via enantioselective conjugate additions. These reactions employ dialkylzinc nucleophiles, maximizing functional group compatibility, while the presence of a Meldrum's acid moiety in the product allows a variety of postaddition modifications. A full investigation of this reaction has determined the structural factors of the alkylidene that contribute to optimal enantioselectivity. We have also used these acceptors to form tertiary propargylic stereocenters in very high enantiomeric excess by an extremely mild, Rh(I)-catalyzed addition of TMS-acetylene. Overall, we demonstrate that Meldrum's acid and its derivatives provide access to a broad range of reactivities that, combined with their ease of handling and preparation, make them ideal electrophiles. PMID:20000793

Dumas, Aaron M; Fillion, Eric

2010-03-16

100

Carbon Dioxide Information Analysis Center and World Data Center-A for atmospheric trace gases: FY 1993 activities  

SciTech Connect

During the course of a fiscal year, Oak Ridge National Laboratory`s Carbon Dioxide Information Analysis Center (CDIAC) distributes thousands of specialty publications-numeric data packages (NDPs), computer model packages (CMPs), technical reports, public communication publications, newsletters, article reprints, and reference books-in response to requests for information related to global environmental issues, primarily those pertaining to climate change. CDIAC`s staff also provide technical responses to specific inquiries related to carbon dioxide (CO{sub 2}), other trace gases, and climate. Hundreds of referrals to other researchers, policy analysts, information specialists, or organizations are also facilitated by CDIAC`s staff. This report provides an account of the activities accomplished by CDIAC (including World Data Center-A for Atmospheric Trace Gases) during the period October 1, 1992, to September 30, 1993. An organizational overview of CDIAC and its staff is supplemented by a detailed description of inquiries received and CDIAC`s response to those inquiries. An analysis and description of the preparation and distribution of NDPS, CMPS, technical reports, newsletters, fact sheets, specialty publications, and reprints are provided. Comments and descriptions of CDIAC`s information management systems, professional networking, and special bilateral agreements are also presented.

Cushman, R.M. [Oak Ridge National Lab., TN (United States). Carbon Dioxide Information Analysis Center; Stoss, F.W. [Oak Ridge National Lab., TN (United States). Carbon Dioxide Information Analysis Center]|[Univ. of Tennessee, Knoxville, TN (United States). Energy, Environment, and Resources Center

1994-01-01

101

One carbon metabolism in anaerobic bacteria: Regulation of carbon and electron flow during organic acid production  

Microsoft Academic Search

The project deals with understanding the fundamental biochemical mechanisms that physiologically control and regulate carbon and electron flow in anaerobic chemosynthetic bacteria that couple metabolism of single carbon compounds and hydrogen to the production of organic acids (formic, acetic, butyric, and succinic) or methane. The authors compare the regulation of carbon dioxide and hydrogen metabolism by fermentation, enzyme, and electron

J. G. Zeikus; M. Jain

1993-01-01

102

Evaluation of Perforated Carbonate Cores Under Acid Stimulation  

E-print Network

Although it has been shown that clean perforation tunnels facilitate the evolution of a single, deeper-penetrating wormhole, there are no reported applications of reactive shaped charges in carbonates prior to acid stimulation. The present study...

Diaz, Nerwing Jose

2011-10-21

103

Study of Acid Response of Qatar Carbonate Rocks  

E-print Network

-scale heterogeneities which may cause the impact of the injected acids to differ from homogenous case. Recent published field data indicate a much smaller number of pore volume to breakthrough compared with experimental measurement with homogeneous carbonate...

Wang, Zhaohong

2012-02-14

104

The inhibition of mitochondrial cytochrome oxidase by the gases carbon monoxide, nitric oxide, hydrogen cyanide and hydrogen sulfide: chemical mechanism and physiological significance  

Microsoft Academic Search

The four gases, nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H2S) and hydrogen cyanide (HCN) all readily inhibit oxygen consumption by mitochondrial cytochrome oxidase. This inhibition\\u000a is responsible for much of their toxicity when they are applied externally to the body. However, recently these gases have\\u000a all been implicated, to greater or lesser extents, in normal cellular signalling events.

Chris E. Cooper; Guy C. Brown

2008-01-01

105

Carbonic Anhydrase 5 Regulates AcidBase Homeostasis in Zebrafish  

Microsoft Academic Search

The regulation of the acid-base balance in cells is essential for proper cellular homeostasis. Disturbed acid-base balance directly affects cellular physiology, which often results in various pathological conditions. In every living organism, the protein family of carbonic anhydrases regulate a broad variety of homeostatic processes. Here we describe the identification, mapping and cloning of a zebrafish carbonic anhydrase 5 (ca5)

Ruben Postel; Arnoud Sonnenberg

2012-01-01

106

Porosity in granular carbons activated with phosphoric acid  

Microsoft Academic Search

Three series of activated carbon have been prepared by heat treatment of peach stones impregnated with solutions of phosphoric acid, in order to analyze the effect of phosphoric acid on the yield, bulk density and porosity of the resultant activated carbons. The analysis of the adsorption isotherms of N2 at 77 K. CO2 at 273 K and n-C4H10, at 273

M. Molina-Sabio; F. RodRíguez-Reinoso; F. Caturla; M. J. Sellés

1995-01-01

107

Effects of acidic treatment of activated carbons on dye adsorption  

Microsoft Academic Search

The effect of acidic treatments of activated carbons on dye adsorption was investigated. The physico-chemical properties of activated carbons were characterised by N2 adsorption, mass titration, temperature-programmed desorption (TPD), and X-ray photoelectron spectrometry (XPS). It was found that surface chemistry plays an important role in dye adsorption. HNO3 treatment produces more active acidic surface groups such as carboxyl and lactone,

Shaobin Wang; Z. H. Zhu

2007-01-01

108

40 CFR 60.52b - Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2010 CFR

...affected facility any gases that contain sulfur...affected facility any gases that contain hydrogen chloride in excess of...percent of the potential hydrogen chloride emission concentration...affected facility any gases that contain...

2010-07-01

109

40 CFR 60.52b - Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2011 CFR

...affected facility any gases that contain sulfur...affected facility any gases that contain hydrogen chloride in excess of...percent of the potential hydrogen chloride emission concentration...affected facility any gases that contain...

2011-07-01

110

40 CFR 60.52b - Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2013 CFR

...affected facility any gases that contain sulfur...affected facility any gases that contain hydrogen chloride in excess of...percent of the potential hydrogen chloride emission concentration...affected facility any gases that contain...

2013-07-01

111

40 CFR 60.52b - Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2012 CFR

...affected facility any gases that contain sulfur...affected facility any gases that contain hydrogen chloride in excess of...percent of the potential hydrogen chloride emission concentration...affected facility any gases that contain...

2012-07-01

112

Determination of carbon monoxide, methane and carbon dioxide in refinery hydrogen gases and air by gas chromatography  

Microsoft Academic Search

This paper illustrates a method for determining trace amounts of CO, CH4 and CO2 with the detection limit of 0.15, 0.15 and 0.20 ?g\\/l, respectively, in refinery hydrogen gases or in air. A simple modification of a gas chromatograph equipped with a flame-ionization detector is presented. A Porapak Q column, additionally connected with a short molecular sieve 5A packed column

Marian Kami?ski; Rafa? Kartanowicz; Daniel Jastrz?bski; Marcin M. Kami?ski

2003-01-01

113

High rate chemical vapor deposition of carbon films using fluorinated gases  

DOEpatents

A high rate, low-temperature deposition of amorphous carbon films is produced by PE-CVD in the presence of a fluorinated or other halide gas. The deposition can be performed at less than 100.degree. C., including ambient room temperature, with a radio frequency plasma assisted chemical vapor deposition process. With less than 6.5 atomic percent fluorine incorporated into the amorphous carbon film, the characteristics of the carbon film, including index of refraction, mass density, optical clarity, and chemical resistance are within fifteen percent (15%) of those characteristics for pure amorphous carbon films, but the deposition rates are high.

Stafford, Byron L. (Arvada, CO); Tracy, C. Edwin (Golden, CO); Benson, David K. (Golden, CO); Nelson, Arthur J. (Longmont, CO)

1993-01-01

114

Carbon formation on metal carbides in chlorine-containing gases at high temperature  

NASA Astrophysics Data System (ADS)

The formation of a carbon film on exposed surfaces has been observed after corrosion of silicon carbide, TiC, and TaC materials in chlorine containing environments. The formation of carbon film during chlorination of silicon carbide and some metal carbides are expected thermodynamically because of the relative stability of silicon or metal halides in comparison to carbon halogen compounds. Carbon or carbide coatings are widely used to improve the properties of engineering materials. Carbon coating with varying structure and composition are applied in fields from tribology to catalysis. There is not yet sufficient published information about the structure and properties of carbon films produced by etching in halogen containing media to determine whether these coatings have useful properties. This paper reports the results of investigations on the carbon films formed on beta-SiC, TiC, and TaC, after exposure to atmospheres containing chlorine and its compounds. Raman spectroscopy, XRD, and SEM have been applied to characterize the effects of the environment and substrate on the structure and properties of carbon film. In addition, spsp3-C rich carbon (or DLC, diamond) was formed on the surface of beta-SiC powder by the reaction in a chlorine-hydrogen gas mixture at atmospheric pressure and temperature 800-900 C.

Jeon, In-Deok

115

The Effect of Acid Additives on Carbonate Rock Wettability and Spent Acid Recovery in Low Permeability Gas Carbonates.  

E-print Network

??Spent acid retention in the near-wellbore region causes reduction of relative permeability to gas and eventually curtailed gas production. In low-permeability gas carbonate reservoirs, capillary… (more)

Saneifar, Mehrnoosh

2012-01-01

116

Swellable, water- and acid-tolerant polymer sponges for chemoselective carbon dioxide capture.  

PubMed

To impact carbon emissions, new materials for carbon capture must be inexpensive, robust, and able to adsorb CO2 specifically from a mixture of other gases. In particular, materials must be tolerant to the water vapor and to the acidic impurities that are present in gas streams produced by using fossil fuels to generate electricity. We show that a porous organic polymer has excellent CO2 capacity and high CO2 selectivity under conditions relevant to precombustion CO2 capture. Unlike polar adsorbents, such as zeolite 13x and the metal-organic framework, HKUST-1, the CO2 adsorption capacity for the hydrophobic polymer is hardly affected by the adsorption of water vapor. The polymer is even stable to boiling in concentrated acid for extended periods, a property that is matched by few microporous adsorbents. The polymer adsorbs CO2 in a different way from rigid materials by physical swelling, much as a sponge adsorbs water. This gives rise to a higher CO2 capacities and much better CO2 selectivity than for other water-tolerant, nonswellable frameworks, such as activated carbon and ZIF-8. The polymer has superior function as a selective gas adsorbent, even though its constituent monomers are very simple organic feedstocks, as would be required for materials preparation on the large industrial scales required for carbon capture. PMID:24874971

Woodward, Robert T; Stevens, Lee A; Dawson, Robert; Vijayaraghavan, Meera; Hasell, Tom; Silverwood, Ian P; Ewing, Andrew V; Ratvijitvech, Thanchanok; Exley, Jason D; Chong, Samantha Y; Blanc, Frédéric; Adams, Dave J; Kazarian, Sergei G; Snape, Colin E; Drage, Trevor C; Cooper, Andrew I

2014-06-25

117

Carbon dioxide production from combustion exhaust gases with nitrogen and argon by-product recovery  

SciTech Connect

This patent describes a method for producing carbon dioxide and nitrogen from combustion exhaust gas containing less than about 10% oxygen by weight. It comprises treating the exhaust gas to remove particulate matter; compressing the exhaust gas to a pressure in the range from about 25 psia to about 200 psia; purifying the exhaust gas to remove trace contaminants; separating the exhaust gas to produce a carbon dioxide rich fraction and a nitrogen rich fraction; liquefying the carbon dioxide rich fraction and distilling off components that are more volatile than carbon dioxide; purifying the nitrogen rich fraction to remove carbon dioxide; and cryogenically fractionally distilling the nitrogen rich fraction to remove oxygen and argon therefrom.

Krishnamurthy, R.; Andrecovich, M.J.

1992-03-31

118

Procedures for safe handling of off-gases from electric vehicle lead-acid batteries during overcharge  

SciTech Connect

The potential for generation of toxic gases from lead-acid batteries has long been recognized. Prior to the current interest in electric vehicles, there were no studies specificaly oriented to toxic gas release from traction batteries, however. As the Department of Energy Demonstration Project (in the Electric and Hybrid Vehicle Program) progresses, available data from past studies and parallel health effects programs must be digested into guidance to the drivers and maintenance personnel, tailored to their contact with electric vehicles. The basic aspects of lead-acid battery operation, vehicle use, and health effects of stibine and arsine to provide electric vehicle users with the information behind the judgment that vehicle operation and testing may proceed are presented. Specifically, it is concluded that stibine generation or arsine generation at rapid enough rates to induce acute toxic response is not at all likely. Procedures to guard against low-level exposure until more definitive data on ambient concentrations of the gases are collected are presented for both charging the batteries and driving the vehicles. A research plan to collect additional quantitative data from electric traction batteries is presented.

LaBelle, S.J.; Bhattacharyya, M.H.; Loutfy, R.O.; Varma, R.

1980-01-25

119

Characterization of carbon black modified by maleic acid  

NASA Astrophysics Data System (ADS)

We present here a method for modifying the surface of carbon black (CB) using a simple heat treatment in the presence of a carboxylic acid as well as water or ethylene glycol as a solvent. CB was mixed with maleic acid and either water or ethylene glycol, and heated at 250°C. Unlike the traditional surface modification processes which use heat treatment of carbon with mineral acids the present modification method using a carboxylic acid proved to be simple and time efficient. CB from two different vendors was used, and the modified samples were characterized by TGA, BET surface area measurement, XRD, particle size and zeta potential measurements, and FTIR. It was found that several material properties, including thermal stability and surface area, of the modified CB are significantly altered relative to the parental carbon samples. This method provides a rapid and simple route to tailor new materials with desired properties.

Asokan, Vijayshankar; Kosinski, Pawel; Skodvin, Tore; Myrseth, Velaug

2013-09-01

120

Do Agricultural Soils of California have the Potential to Sequester Carbon and Mitigate Greenhouse Gases?  

NASA Astrophysics Data System (ADS)

Agricultural ecosystems play a major role in the global carbon cycle and can be both sources of carbon emissions to the atmosphere and also carbon sinks which may be used to offset any future greenhouse gas (GHG) emissions. In California, climate change predictions indicate major impacts and substantial alterations of agricultural systems over the next decades. In 2006, California passed the California Global Warming Solutions Act of 2006 (AB 32) that requires reduction of the three major GHG's (CO2, N2O and CH4) to 1990 levels by 2020. We surveyed and synthesized available data from recent studies describing the potential to sequester carbon and reduce other GHG emissions in California agricultural soils. The studies evaluated various management practices in both annual row and perennial cropping systems, with other studies focusing upon biogeochemical model predictions for carbon sequestration and GHG mitigation calibrated towards California agriculture. Management practices considered included minimum or no tillage, cover cropping, organic residue (low and high inputs) and nitrogen fertilizer management. Though practices involving inputs of carbon, such as cover cropping and organic amendments, were often associated with increases in soil organic carbon (SOC) in the top soil layer (0-20 cm), results were not consistent across farming systems. Several studies indicated that conservation tillage, alone, increased above-ground biomass, especially when used with a cover crop. However, the reduced soil disturbance from conservation tillage merely resulted in a redistribution of the soil carbon rather than an overall accumulation, when compared with standard tillage and cover cropping practices together. Predictions from biogeochemical models indicated that increased inputs of manure and increased organic residues led to substantial carbon sequestration but did not consistently reduce non-CO2 related GHG emissions. The most effective way to reduce non-CO2 GHG emissions, and simultaneously add organic matter to soil, was to employ reduced tillage techniques and low input farming which is based upon the reduction of chemical fertilizers, pesticides and herbicides without their complete elimination and to also add carbon to the soils through the addition and incorporation of organic amendments and cover crops.

Suddick, E. C.; Scow, K. M.; Six, J. W.

2008-12-01

121

Regiocontrolled intramolecular cyclizations of carboxylic acids to carbon-carbon triple bonds promoted by acid or base catalyst.  

PubMed

We systematically investigated, for the first time, the relationship between regioselectivity and acid/base effects in the cyclization reactions between carboxylic acids and carbon-carbon triple bonds. We found novel acid- and base-promoted cyclizations to selectively give isocoumarin or pyran-2(2H)-one and phthalide or furan-2(5H)-one skeletons, respectively, and established a catalytic version of regioselective heterocyclic ring synthesis. Density functional theory calculations and application to a short route to thunberginol A were also described. [reaction: see text]. PMID:17107061

Uchiyama, Masanobu; Ozawa, Hiroki; Takuma, Kazuya; Matsumoto, Yotaro; Yonehara, Mitsuhiro; Hiroya, Kou; Sakamoto, Takao

2006-11-23

122

FIELD METHOD COMPARISON FOR THE CHARACTERIZATION OF ACID AEROSOLS AND GASES  

EPA Science Inventory

This paper presents findings from two intercomparison studies of acid aerosol measurement systems, which were conducted in Uniontown and State College, PA, during the summers of 1990 and 1991, respectively. s part of these studies, acid aerosol and gas concentrations (NH3, HNO3, ...

123

The Effect Of Viscoelastic Surfactants Used In Carbonate Matrix Acidizing On Wettability  

E-print Network

Carbonate reservoirs are heterogeneous; therefore, proper acid placement/diversion is required to make matrix acid treatments effective. Viscoelastic surfactants (VES) are used as diverting agents in carbonate matrix acidizing. However...

Adejare, Oladapo

2012-07-16

124

Measurement of fossil fuel derived carbon dioxide and other anthropogenic trace gases above Sacramento, California in Spring 2009  

NASA Astrophysics Data System (ADS)

Direct quantification of fossil fuel CO2 (CO2ff) in atmospheric samples can be used to examine several carbon cycle and air quality questions. We collected in situ CO2, CO, and CH4 measurements and flask samples in the boundary layer and free troposphere over Sacramento, California, USA, during two aircraft flights over and downwind of this urban area during spring of 2009. The flask samples were analyzed for ?14CO2 and CO2 to determine the recently added CO2ff mole fraction. A suite of additional greenhouse gases including hydrocarbons and halocarbons were measured in the same samples. Strong correlations were observed between CO2ff and numerous trace gases associated with urban emissions. From these correlations we estimate emission ratios between CO2ff and these species, and compare these with bottom-up inventory-derived estimates. Recent county level inventory estimates for carbon monoxide (CO) and benzene from the California Air Resources Board CEPAM database are in good agreement with our measured emission ratios, whereas older emissions inventories appear to overestimate emissions of these gases. For most other trace species, there are substantial differences between our measured emission ratios and those derived from available emission inventories. For the first flight, we combine in situ CO measurements with the measured CO:CO2ff emission ratio of 14±2 ppbCO/ppmCO2 to derive an estimate of CO2ff mole fraction throughout this flight, and also estimate the biospheric CO2 mixing ratio (CO2bio) from the difference of total and fossil CO2. The resulting CO2bio varies substantially between air in the urban plume and the surrounding boundary layer air. Finally, we use the in situ estimates of CO2ff mole fraction to infer total fossil fuel CO2 emissions from the Sacramento region, using a mass balance approach. The resulting CO2ff emission estimate is uncertain to within a factor of two due to uncertainties in wind speed and boundary layer height. Nevertheless, this first attempt to estimate urban-scale CO2ff from atmospheric radiocarbon measurements shows that CO2ff can be used to verify and improve emission inventories for many poorly known anthropogenic species, separate biospheric CO2, and indicates the potential to constrain the CO2ff emissions if transport uncertainties are reduced.

Turnbull, J. C.; Karion, A.; Fischer, M. L.; Faloona, I. C.; Guilderson, T. P.; Lehman, S. J.; Miller, B. R.; Miller, J. B.; Montzka, S. A.; Sherwood, T.; Saripalli, S.; Sweeney, C.; Tans, P. P.

2010-12-01

125

Measurement of fossil fuel derived carbon dioxide and other anthropogenic trace gases above Sacramento, California in Spring 2009  

NASA Astrophysics Data System (ADS)

Direct quantification of fossil fuel CO2 (CO2ff) in atmospheric samples can be used to examine several carbon cycle and air quality questions. We collected in-situ CO2, CO, and CH4 measurements and flask samples in the boundary layer and free troposphere over Sacramento, California, USA, during two aircraft flights over and downwind of this urban area during spring of 2009. The flask samples were analyzed for ?14CO2 and CO2 to determine the recently added CO2ff mole fraction. A suite of additional greenhouse gases including hydrocarbons and halocarbons were measured in the same samples. Strong correlations were observed between CO2ff and numerous trace gases associated with urban emissions. From these correlations we estimate emission ratios between CO2ff and these species, and compare these with bottom-up inventory-derived estimates. Recent county level inventory estimates for carbon monoxide (CO) and benzene from the California Air Resources Board CEPAM database are in good agreement with our measured emission ratios, whereas older emissions inventories appear to overestimate emissions of these gases. For most other trace species, there are substantial differences between our measured emission ratios and those derived from available emission inventories. For the first flight, we combine in situ CO measurements with the measured CO:CO2ff emission ratio of 14±2 ppbCO/ppmCO2 to derive an estimate of CO2ff mole fraction throughout this flight, and also estimate the biospheric CO2 mixing ratio (CO2bio) from the difference of total and fossil CO2. The resulting CO2bio varies substantially between air in the urban plume and the surrounding boundary layer air. Finally, we use the in situ estimates of CO2ff mole fraction to infer total fossil fuel CO2 emissions from the Sacramento region, using a mass balance approach. However the resulting emissions are uncertain to within a factor of two due to uncertainties in wind speed and boundary layer height. Nevertheless, this first attempt to estimate urban-scale CO2ff from atmospheric radiocarbon measurements shows that CO2ff can be used to verify and improve emission inventories for many poorly known anthropogenic species, separate biospheric CO2, and indicates the potential to constrain the CO2ff emissions if transport uncertainties are reduced.

Turnbull, J. C.; Karion, A.; Fischer, M. L.; Faloona, I.; Guilderson, T.; Lehman, S. J.; Miller, B. R.; Miller, J. B.; Montzka, S.; Sherwood, T.; Saripalli, S.; Sweeney, C.; Tans, P. P.

2010-09-01

126

Coal fly ash based carbons for SO2 removal from flue gases.  

PubMed

Two different coal fly ashes coming from the burning of two coals of different rank have been used as a precursor for the preparation of steam activated carbons. The performance of these activated carbons in the SO(2) removal was evaluated at flue gas conditions (100 degrees C, 1000 ppmv SO(2), 5% O(2), 6% H(2)O). Different techniques were used to determine the physical and chemical characteristics of the samples in order to explain the differences found in their behaviour. A superior SO(2) removal capacity was shown by the activated carbon obtained using the fly ash coming from a sub-bituminous-lignite blend. Experimental results indicated that the presence of higher amount of certain metallic oxides (Ca, Fe) in the carbon-rich fraction of this fly ash probably has promoted a deeper gasification in the activation with steam. A more suitable surface chemistry and textural properties have been obtained in this case which explains the higher efficiency shown by this sample in the SO(2) removal. PMID:20167465

Rubio, B; Izquierdo, M T

2010-07-01

127

Reevaluation of the NOAA\\/CMDL carbon monoxide reference scale and comparisons with CO reference gases at NASA-Langley and the Fraunhofer Institut  

Microsoft Academic Search

The carbon monoxide (CO) reference scale created by the National Oceanic and Atmospheric Administration\\/Climate Monitoring and Diagnostics Laboratory (NOAA\\/CMDL) is used to quantify measurements of CO in the atmosphere, calibrate standards of other laboratories and to otherwise provide reference gases to the community measuring atmospheric CO. This reference scale was created based upon a set of primary standards prepared by

P. C. Novelli; J. E. Collins Jr.; R. C. Myers; G. W. Sachse; H. E. Scheel

1994-01-01

128

Photosynthesis In Elodea canadensis Michx: Four-Carbon Acid Synthesis.  

PubMed

Experiments to determine the early labeled photosynthetic products in Elodea canadensis show that after 2 seconds of exposure to NaH(14)CO(3), 45% of the (14)C incorporated is located in malate and aspartate. Phosphoglyceric acid and sugars account for 27% of the label during similar exposures. Equivalent amounts of organic acids and C(3) cycle products are present after 8 seconds. Four-carbon acids remain relatively unchanged throughout the first 45 seconds of exposure, while sugars increase in a linear fashion. Enzyme assays indicate that ribulose diphosphate and phosphoenolpyruvate carboxylase enzymes are present in a ratio of approximately 2:1. It appears that E. canadensis is able to synthesize significant amounts of four-carbon acids via beta-carboxylation and this may play a role in maintaining a pH favorable for carboxylation in aquatic plants. PMID:16660008

Degroote, D; Kennedy, R A

1977-06-01

129

ACIDIC GASES AND AEROSOLS IN THE EASTERN AND WESTERN UNITED STATES  

EPA Science Inventory

The USEPA National Dry Deposition Network (NDDN) is designed to provide long-term estimates of acidic gas and aerosol concentrations, and associated fluxes, across the continental United States. nspection of data collected since 1988 shows species-dependent variability in atmosph...

130

Acidic gases and nitrate and sulfate particles in the atmosphere in the city of Guadalajara, México.  

PubMed

Atmospheric concentrations of nitrous acid, nitric acid, nitrate and sulfate particles were obtained in this study from April to June 2008 in the center of the city of Guadalajara, while concentrations of ozone, sulfur dioxide, nitrogen dioxide and meteorological parameters (temperature and relative humidity), were acquired by the Secretaría del Medio Ambiente para el Desarrollo Sustentable del Estado de Jalisco (SEMADES). The results showed that nitric acid (2.7 ?g m(-3)) was 2.7 times higher than nitrous acid (1.0 ?g m(-3)). The sulfur dioxide (SO(2)) concentration indicated an opposite trend to sulfate (SO(4) (2-)), with the average concentration of SO(2) (6.9 ?g m(-3)) higher in almost the entire period of study. The sulfur conversion ratio (Fs, 24.9%) and nitrogen conversion ratio (Fn, 6.2%), were revealed to be similar to that reported in other urban areas during warm seasons. It is also noted that ozone is not the main oxidizer of nitrogen dioxide and sulfur dioxide. This determination was made by taking into account the slightly positively correlation determined for Fn (r(2) = 0.084) and Fs (r(2) = 0.092) with ozone that perhaps suggests there are other oxidizing species such as the radical OH, which are playing an important role in the processes of atmospheric oxidation in this area. PMID:22358115

Saldarriaga-Noreña, Hugo; Waliszewski, Stefan; Murillo-Tovar, Mario; Hernández-Mena, Leonel; de la Garza-Rodríguez, Iliana; Colunga-Urbina, Edith; Cuevas-Ordaz, Rosalva

2012-05-01

131

Sulfuric acid vapor and other cloud-related gases in the Venus atmosphere - Abundances inferred from observed radio opacity  

NASA Technical Reports Server (NTRS)

It is suggested that the absorbing characteristics of sulfuric acid vapor appear to reconcile what had been thought to be an inconsistency among measurements and deductions regarding the constituents of the Venus atmosphere and radio occultation, radar reflection, and radio emission measurements of its opacity. Laboratory measurements of sulfuric acid, sulfur dioxide, water vapor, and carbon dioxide are used to model relative contributions to opacity as a function of height in a way that is consistent with observations of the constituents and absorbing properties of the atmosphere. It is concluded that sulfuric acid vapor is likely to be the principal microwave absorber in the 30-50 km altitude range of the middle atmosphere of Venus.

Steffes, P. G.; Eshleman, V. R.

1982-01-01

132

Separation of polar gases from nonpolar gases  

DOEpatents

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

Kulprathipanja, Santi (Hoffman Estates, IL); Kulkarni, Sudhir S. (Hoffman Estates, IL)

1986-01-01

133

Separation of polar gases from nonpolar gases  

DOEpatents

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

Kulprathipanja, S.; Kulkarni, S.S.

1986-08-26

134

Enhancement of acidic gases in biomass burning impacted air masses over Canada  

NASA Technical Reports Server (NTRS)

Biomass-burning impacted air masses sampled over central and eastern Canada during the summer of 1990 as part of ABLE 3B contained enhanced mixing ratios of gaseous HNO3, HCOOH, CH3COOH, and what appears to be (COOH)2. These aircraft-based samples were collected from a variety of fresh burning plumes and more aged haze layers from different source regions. Values of the enhancement factor, delta X/delta CO, where X represents an acidic gas, for combustion-impacted air masses sampled both near and farther away from the fires, were relatively uniform. However, comparison of carboxylic acid emission ratios measured in laboratory fires to field plume enhancement factors indicates significant in-plume production of HCOOH. Biomass-burning appears to be an important source of HNO3, HCOOH, and CH3COOH to the troposphere over subarctic Canada.

Lefer, B. L.; Talbot, R. W.; Harriss, R. C.; Bradshaw, J. D.; Sandholm, S. T.; Olson, J. O.; Sachse, G. W.; Collins, J.; Shipham, M. A.; Blake, D. R.

1994-01-01

135

Understanding the fluvial loss of carbon from UK watersheds - implications for terrestrial carbon; greenhouse gases and water quality  

NASA Astrophysics Data System (ADS)

This study develops a number of methods for estimating the fate of fluvial carbon through UK watersheds. The study considers dissolved organic carbon (DOC); particulate organic carbon (POC); and dissolved CO2. The study considers the loss from the terrestrial source; in-stream losses and production; and export to the continental shelf. The study used multiple approaches, including: mass balance studies; modelling and experimentation. i) Mass balance studies suggest that the UK losses 5 Mtonnes C/yr (21.8 tonnes C/km2/yr) from soils in the proportion of 7:22:4 (POC:DOC:diss. CO2). The mass balance studies suggest 3.5 Mtonnes C/yr (15.2 tonnes C/km2/yr) is lost to the atmosphere in the proportion 8:75:17 (POC:DOC:diss. CO2). ii) UK rivers have short residence times (typically 1-2 days) and so the diurnal cycle becomes critical. Experiments show that turnover rates are close to zero overnight but that these can be periods of DOC production from turnover of POC. iii) Development and modelling using physical rate showed that the loss of the DOC was between 24 and 37% - lower than that estimated from mass balance studies, but that the loss rate of TOC (DOC + POC) was between 57 and 80% - close to that estimated from mass balance studies. iv) Studies of molecular change suggest that nutrient supply is the limiting factor on turnover and that a position of 'pseudo-equilibirum' is achieved that limits the net effect of the fluvial processes.

Worrall, F.; Moody, C.; Burt, T. P.; Howden, N. J.

2013-12-01

136

ELEMENTAL MERCURY ADSORPTION BY ACTIVATED CARBON TREATED WITH SULFURIC ACID  

EPA Science Inventory

The paper gives results of a study of the adsorption of elemental mercury at 125 C by a sulfuric-acid (H2S04, 50% w/w/ solution)-treated carbon for the removal of mercury from flue gas. The pore structure of the sample was characterized by nitrogen (N2) at -196 C and the t-plot m...

137

Efficacy of Carbonic Acid as an Anesthetic for Rainbow Trout  

Microsoft Academic Search

We determined effective concentration ranges for carbonic acid as an anesthetic for rainbow trout Oncorhynchus mykiss across a wide range of water temperatures and alkalinities. Effective concentrations were based on criteria for induction time (<3 min), recovery time (<10 min), and 72-h survival (100%). Induction time decreased and recovery time increased with increasing concentration. Mortalities were associated with high concentrations

Kevin R. Gelwicks; David J. Zafft; Joe P. Bobbitt

1998-01-01

138

Buffer Capacities of Leaves, Leaf Cells, and Leaf Cell Organelles in Relation to Fluxes of Potentially Acidic Gases 1  

PubMed Central

Since environmental pollution by potentially acidic gases such as SO2 causes proton release inside leaf tissues, homogenates of needles of spruce (Picea abies) and fir (Abies alba) and of leaves of spinach (Spinacia oleracea) and barley (Hordeum vulgare) were titrated and buffer capacities were determined as a function of pH. Titration curves of barley leaves were compared with titration curves of barley mesophyll protoplasts. From the protoplasts, chloroplasts and vacuoles were isolated and subjected to titration experiments. From the titration curves, the intracellular distribution of buffering capacities could be deduced. Buffering was strongly pH-dependent. It was high at the extremes of pH but still significant close to neutrality. Owing to its large size, the vacuole was mainly responsible for cellular buffering. However, on a unit volume basis, the cytoplasm was much more strongly buffered than the vacuole. Potentially acidic gases are trapped in the anionic form. They release protons when trapped. The magnitude of diffusion gradients from the atmosphere into the cells, which determines flux, depends on intracellular pH. In the light, the chloroplast stroma, as the most alkaline leaf compartment, has the highest trapping potential. Acidification of the chloroplast stroma inhibits photosynthesis. The trapping potential of the chloroplast is followed by that of the cytosol. Compared with the cytoplasm, the vacuole possesses little trapping potential in spite of its large size. It is particularly small in the acidic vacuoles of conifer needles. In the physiological pH range (slightly above neutrality), chloroplast buffering was about 1 microequivalents H+ per milligram chlorophyll per pH unit or 35 microequivalents H+ per milliliter per pH unit in barley or spinach chloroplasts. This compares with SO2-generated H+ production of somewhat more than 1 microequivalent H+ per milligram chlorophyll per hour, which results from observed SO2 uptake of leaves when stomata were open and the atmospheric SO2 concentration was 0.4 microliters per liter (GE Taylor Jr, DT Tingey 1983 Plant Physiol 72: 237-244). At lower SO2 concentrations, similar H+ generation inside the cells requires correspondingly longer exposure times. PMID:16664863

Pfanz, Hardy; Heber, Ulrich

1986-01-01

139

Research and development on membrane processes for removal of acid gases during coal gasification. Final report, 20 June 1975-19 October 1976  

Microsoft Academic Search

The object of this program was to develop novel and unique membranes for separating acid gases from coal gasification streams. Many candidate membranes, including cationic, hydrophilic, and silicone, were tested. Optimum separation properties were possessed by membranes formulated from crosslinked methyl cellulose coated on polysulfone support films. The observed separation properties were explained theoretically by the solubility of the various

R. J. Petersen; J. E. Cadotte; E. J. Conway; R. H. Forester; M. J. Steuck

1976-01-01

140

High-sensitive monitoring of carbon monoxide in industry flue gases using tunable diode lasers  

NASA Astrophysics Data System (ADS)

Carbon monoxide (CO) is a very important gas generated in the industrial process; therefore to implement CO concentration on-line monitoring is a key factor for industrial process control. Tunable diode laser absorption spectroscopy (TDLAS) is a high sensitive, high selective and fast trace gas detection technique. With the features of tunability and narrow linewidth of distributed feedback (DFB) laser and by precisely tuning its wavelength to a single isolated absorption line of the gas, TDLAS technique can be utilized to accurately perform online gas concentration monitoring with very high sensitivity. In this paper, a system for online monitoring of CO concentration is developed by our group employing TDLAS technique. The experimental results are present and discussed in this report. The characteristics of the system are: the sensitivity, 10ppm; detection accuracy, 0.02%; long term stability, 1%.

Zhang, Zhi-rong; Dong, Feng-zhong; Xia, Hua; Tu, Guo-jie; Wu, Bian; Wang, Yu

2009-07-01

141

Carbon dioxide removal from flue gases by absorption/ desorption in aqueous diethanolamine solutions.  

PubMed

The carbon dioxide (CO2) desorption rate from CO2- loaded aqueous diethanolamine (DEA) solutions was measured using a stirred cell with a flat gas-liquid interface. The measurements were performed in the temperature range of 293.15-313.15 K and an amine concentration range of 10-20% mass DEA. Measurements were based on a semibatch isothermal absorption of the gas until the equilibrium state was reached, followed by desorption, which was initiated by the pressure release in the system. A simplified mass transfer model based on the film theory coupled with CO2, mass balance was developed to interpret the experimental data. On the basis of the proposed model, the initial mass transfer rates were calculated from the experimental results. The calculated initial desorption rates enabled estimation of the enhancement factor for CO2 mass transfer from aqueous DEA solutions. Analysis of the experimental data showed that desorption took place in the diffusive mass transfer regime. PMID:20842932

Kierzkowska-Pawlak, Hanna; Chacuk, Andrzej

2010-08-01

142

Laboratory simulation of meteoritic noble gases. II - Sorption of xenon on carbon: Etching and heating experiments  

NASA Technical Reports Server (NTRS)

The release of trapped Xe from amorphous-C phases of meteorites is simulated experimentally by HNO3 etching of carbon-black and pyrolyzed polyvinylidene chloride samples exposed to Xe-127 for 0.5-240 h at 100-1000 C and then degassed for 9 h or more at the same temperatures, as reported by Wacker et al. (1985). The results are presented in tables and graphs and characterized in detail. Samples exposed at 100-200 C are found to lose most of their Xe after etching to a depth of only about 20 pm, while those exposed at 800-1000 C exhibit a second more tightly bound component extending to a depth of 3 nm, indicative of diffusion of Xe during exposure and resembling planetary Xe. The higher noble-gas concentrations measured in meteorites are attributed to rate-controlled Xe uptake over a long period in the solar nebula.

Zadnik, M. G.; Wacker, J. F.; Lewis, R. S.

1985-01-01

143

Acetic Acid bacteria: physiology and carbon sources oxidation.  

PubMed

Acetic acid bacteria (AAB) are obligately aerobic bacteria within the family Acetobacteraceae, widespread in sugary, acidic and alcoholic niches. They are known for their ability to partially oxidise a variety of carbohydrates and to release the corresponding metabolites (aldehydes, ketones and organic acids) into the media. Since a long time they are used to perform specific oxidation reactions through processes called "oxidative fermentations", especially in vinegar production. In the last decades physiology of AAB have been widely studied because of their role in food production, where they act as beneficial or spoiling organisms, and in biotechnological industry, where their oxidation machinery is exploited to produce a number of compounds such as l-ascorbic acid, dihydroxyacetone, gluconic acid and cellulose. The present review aims to provide an overview of AAB physiology focusing carbon sources oxidation and main products of their metabolism. PMID:24426139

Mamlouk, Dhouha; Gullo, Maria

2013-12-01

144

Effect of variation in argon content of calibration gases on determination of atmospheric carbon dioxide.  

PubMed

Carbon dioxide (CO(2)) is a greenhouse gas that makes by far the largest contribution to the global warming of the Earth's atmosphere. For the measurements of atmospheric CO(2) a non-dispersive infrared analyzer (NDIR) and gas chromatography are conventionally being used. We explored whether and to what degree argon content can influence the determination of atmospheric CO(2) using the comparison of CO(2) concentrations between the sample gas mixtures with varying Ar amounts at 0 and 18.6 mmol mol(-1) and the calibration gas mixtures with Ar at 8.4, 9.1, and 9.3 mmol mol(-1). We newly discovered that variation of Ar content in calibration gas mixtures could undermine accuracy for precise and accurate determination of atmospheric CO(2) in background air. The differences in CO(2) concentration due to the variation of Ar content in the calibration gas mixtures were negligible (<+/-0.03 micromol mol(-1)) for NDIR systems whereas they noticeably increased (<+/-1.09 micromol mol(-1)) especially for the modified GC systems to enhance instrumental sensitivity. We found that the thermal mass flow controller is the main source of the differences although such differences appeared only in the presence of a flow restrictor in GC systems. For reliable monitoring of real atmospheric CO(2) samples, one should use calibration gas mixtures that contain Ar content close to the level (9.332 mmol mol(-1)) in the ambient air as possible. Practical guidelines were highlighted relating to selection of appropriate analytical approaches for the accurate and precise measurements of atmospheric CO(2). In addition, theoretical implications from the findings were addressed. PMID:19836498

Min, Deullae; Kang, Namgoo; Moon, Dong Min; Lee, Jin Bok; Lee, Dong Soo; Kim, Jin Seog

2009-12-15

145

Abundance and isotope systematics of carbon in subglacial basalts, geothermal gases and fluids from Iceland's rift zones  

NASA Astrophysics Data System (ADS)

P. H. BARRY1*, D. R. HILTON1, E. FÜRI1, S.A. HALLDÓRSON1, T.P. FISCHER2, K. GRONVOLD3 1 Scripps Institution of Oceanography, UCSD, La Jolla, California 92093, USA (*Correspondence: pbarry@ucsd.edu). 2University of New Mexico, Albuquerque, NM 87131, USA. 3University of Iceland, Askja, Sturlugata 7, IS-101, Reykjavik, Iceland Carbon dioxide (CO2) is the dominant non-aqueous volatile species found in oceanic basalts and geothermal fluids and serves as the carrier gas for trace volatiles such as He and other noble gases. The aim of this study is to identify the superimposed effects of degassing and crustal contamination on the CO2 systematics of the Icelandic hotspot in order to reveal and characterize the carbon abundance and isotopic features of the underlying mantle source. Our approach involves coupling CO2 with He, utilizing the sensitivity of 3He/4He ratios to reveal mantle and crustal inputs. We report new C-isotope (?13C) and abundance characteristics for a suite of 47 subglacial basalts and 50 geothermal gases and fluids from Iceland. CO2 contents in hyaloclastite glasses are extremely low (10-100 ppm) and likely residual following extensive degassing whereas geothermal fluids are dominated by CO2 (>90 %). C-isotopes range from -27.2 to -3.6 ‰ (vs. PDB) for basalts and from -18.8 to 2.86 ‰ (vs. PDB) for geothermal samples (mean = -4.2 ± 3.6 ‰). CO2/3He ratios range from 108 to 1012 for basalts and from 105 to 1012 for geothermal samples: In both cases, our results extend He-CO2 relationships over a much broader range than reported previously [1]. Taken together, these data suggest that several processes including mixing, degassing, and/or syn- or post-eruptive crustal contamination may act to modify CO2 source characteristics. Equilibrium degassing models are compatible with ~75 % of the basalt data, and preliminary results indicate that initial Icelandic source characteristics are ~500 ppm CO2 and ?13C ~ -5 ‰ (vs. PDB). These values are high compared to N-MORB mantle source estimates (72-134 ppm) based upon CO2/Nb ratios [2, 3]; however, they are in good agreement with those from submarine glasses on adjacent segments from the Reykjanes and Kolbeinsey ridges [4,5]. Significantly, the model-derived ?13C estimate is close to the mean Icelandic geothermal value, implying that fluids closely resemble source values, i.e. they likely represent the exsolved component. Integrating the estimated source CO2 content with magma production values of 0.079 km3/yr [6] yields a CO2 flux of ~1.2 x 1011 mol CO2 yr-1for Iceland, representing ~ 5.4 % of the total carbon ridge flux of 2.2 x 1012 mol CO2 yr-1 [7]. Thus, the average CO2 flux estimate for Iceland is ~2.2 x 108 mol CO2 yr-1km-1 strike of ridge axis, which compares to an overall ridge flux (including Iceland) of ~2.9 x 107 mol CO2 yr-1km-1. This difference highlights both heterogeneity in source volatile contents and magma production rates as important controls for determining mantle CO2 fluxes. [1] Poreda et al., 1992 [2] Saal et al., 2002. [3] Shaw et al., 2010. [4] de Leeuw, 2007 [5] Macpherson et al., 2005. [6] Thordarson et al., 2007 [7] Marty et al., 1998.

Barry, P. H.; Hilton, D. R.; Fueri, E.; Halldorsson, S. A.; Fischer, T. P.; Gronvold, K.

2010-12-01

146

Production of sulfur gases and carbon dioxide by synthetic weathering of crushed drill cores from the Santa Cruz porphyry copper deposit near Casa Grande, Pinal County, Arizona  

USGS Publications Warehouse

Samples of ground drill cores from the southern part of the Santa Cruz porphyry copper deposit, Casa Grande, Arizona, were oxidized in simulated weathering experiments. The samples were also separated into various mineral fractions and analyzed for contents of metals and sulfide minerals. The principal sulfide mineral present was pyrite. Gases produced in the weathering experiments were measured by gas chromatography. Carbon dioxide, oxygen, carbonyl sulfide, sulfur dioxide and carbon disulfide were found in the gases; no hydrogen sulfide, organic sulfides, or mercaptans were detected. Oxygen concentration was very important for production of the volatiles measured; in general, oxygen concentration was more important to gas production than were metallic element content, sulfide mineral content, or mineral fraction (oxide or sulfide) of the sample. The various volatile species also appeared to be interactive; some of the volatiles measured may have been formed through gas reactions. ?? 1990.

Hinkle, M.E.; Ryder, J.L.; Sutley, S.J.; Botinelly, T.

1990-01-01

147

The catalytic effect of boric acid on polyacrylonitrile-based carbon fibers and the thermal conductivity of carbon\\/carbon composites produced from them  

Microsoft Academic Search

The catalytic effect of boric acid on the graphitization and surface structure of polyacrylonitrile-based carbon fibers was investigated by dipping fibers in boric acid before heating at 2500°C. The thermal conductivity of carbon\\/carbon composites produced from the modified carbon performs by chemical vapor infiltration was also studied. The results show that the treatment by boric acid has a catalytic-graphitization effect

Jie Chen; Xiang Xiong; Peng Xiao; Hong-Bo Zhang

2010-01-01

148

Simultaneous determination of uric acid and ascorbic acid using glassy carbon electrodes in acetate buffer solution  

Microsoft Academic Search

The present work reports the simultaneous determination of uric acid (UA) and ascorbic acid (AA) in 0.2M, pH 4.0, acetate buffer solution using glassy carbon (GC) electrode by square wave voltammetry. Selective detection of UA in the presence of 200-fold excess of AA is achieved at the GC electrode in acetate buffer solution. The GC electrode separates the voltammetric signal

S. Abraham John

2005-01-01

149

Amino acid adsorption on single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We investigate and discuss the adsorption of a few amino acids on (3,3) carbon nanotubes and on graphite sheets through calculations within density functional theory. Results show weak binding of the biomolecules on both substrates, but through generally favourable adsorption pathways. Zwitterion adsorption through the charged amine and carboxylate groups are bound stronger to the nanotube surface in comparison to their nonionic counterparts, as well as on histidine, phenylalanine, and cysteine side chain groups fixed in specific orientations. Binding strengths on graphite suggest dissimilar trends for amino acid interactions with increasing nanotube diameter.

Roman, T.; Diño, W. A.; Nakanishi, H.; Kasai, H.

2006-04-01

150

Geochemical monitoring of the 2002–2003 eruption at Stromboli volcano (Italy): precursory changes in the carbon and helium isotopic composition of fumarole gases and thermal waters  

Microsoft Academic Search

Significant changes in the helium and carbon isotopic composition of shallow thermal waters vs. gas and a crater fumarolic gas have been recorded at Stromboli prior and during the 2002–2003 eruption. The3He\\/4He ratios corrected for air contamination (Rc\\/Ra), and ?13C of fumarolic gases gradually increased from May to November 2002 before the eruption onset. These variations imply early degassing of

G. Capasso; M. L. Carapezza; C. Federico; S. Inguaggiato; A. Rizzo

2005-01-01

151

Porosity and surface area of monolithic carbon aerogels prepared using alkaline carbonates and organic acids as polymerization catalysts  

Microsoft Academic Search

Carbon aerogels were prepared by polymerization of a resorcinol–formaldehyde mixture using different polymerization catalysts such as: sodium or potassium carbonates, oxalic acid or para-toluenesulfonic acid. The carbon aerogel obtained with this last acid was further CO2-activated to 8.5% and 22% burn-off. All samples were characterized by N2 and CO2 adsorption at ?196 and 0°C, respectively, and by mercury porosimetry, scanning

D. Fairén-Jiménez; F. Carrasco-Marín; C. Moreno-Castilla

2006-01-01

152

ANALYSIS OF COMMERCIAL CYLINDER GASES OF NITRIC OXIDE, SULFUR DIOXIDE, AND CARBON MONOXIDE AT SOURCE CONCENTRATIONS: RESULTS OF AUDIT 5  

EPA Science Inventory

Manufacturers of commercial cylinder gases supply standards with a certified analysis and a statement of accuracy. Generally, the level of accuracy is specified as a percentage of the component value. To ascertain the accuracy of analyses of commercially available cylinder gases,...

153

Effects of Lime and Carbonate of Lime on Acid Phosphate.  

E-print Network

phosphate. AcL 0.1 grzm calcium carbonate mixed with the acid phosphate be- fore putting in the soil. One gram sulphate of potash and 1 gram ammonium nitrate added to all pots. Corn pIanted May S, harvested Julv 10-14, 1911. Four stalks. One gram... .................. ' 1,ah. No. 3653 3653 .0004 0015 0 .0433 .0113 4604 1 -AC corn. .................... ........................... 2-AC. 3-ACL ........................... ........................... 4-ACL I-AC sorghum. ........... : .... 2-AC...

Fraps, G. S. (George Stronach)

1917-01-01

154

Carbon Isotope Ratios in Crassulacean Acid Metabolism Plants  

PubMed Central

A year round study of photosynthesis and carbon isotope fractionation was conducted with plants of Opuntia phaeacantha Engelm. and Yucca baccata Torr. occurring in natural stands at elevations of 525, 970, 1450 and 1900 m. Plant water potentials and the daytime pattern of 14CO2 photosynthesis were similar for all cacti along the elevational gradient, despite significant differences in temperature regime and soil water status. Carbon isotope ratios of total tissue and soluble extract fractions were relatively constant throughtout the entire year. Additionally, the ?13C values were similar in all plants of the same species along the elevational gradient, i.e. ?12.5 ± 0.86 ‰ for O. phaeacantha and ?15.7 ± 0.95 ‰ for Y. baccata. The results of this study indicate Crassulacean acid metabolism predominates as the major carbon pathway of these plants, which do not facultatively utilize the reductive pentose phosphate cycle of photosynthesis as the primary carboxylation reaction. PMID:16659680

Szarek, Stan R.; Troughton, John H.

1976-01-01

155

40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

...not cause to be discharged into the atmosphere from that affected facility any gases...not cause to be discharged into the atmosphere from that affected facility any gases...not cause to be discharged into the atmosphere from that affected facility any...

2014-07-01

156

REACTIONS OF CHLORITE WITH ACTIVATED CARBON AND WITH VANILLIC ACID AND INDAN ADSORBED ON ACTIVATED CARBON  

EPA Science Inventory

The reaction between chlorite (CO2(-1)) and vanillic acid, at pH 6.0 in the presence of granular activated carbon (GAC), yielded several reaction products identifiable by GC/MS; no products were found in the absence of GAC. Indan and ClO2 or ClO2(-1) reacted in aqueous solution a...

157

Black Carbon in Sedimentary Organic Carbon in the Northeast Pacific using the Benzene Polycarboxylic Acid Method  

NASA Astrophysics Data System (ADS)

Black carbon (BC) in the Northeast Pacific ultrafiltered dissolved organic matter (UDOM) was found to be surprisingly old with a 14C age of 18,000 +/-3,000 14C years (Ziolkowski and Druffel, 2010) using the Benzene Polycarboxylic Acid (BPCA) method, while BC in sedimentary organic carbon (SOC) was found to be 2,400-12,900 14C years older than non-BC SOC (Masiello and Druffel, 1998) with a different method. Using the dichromate-sulfuric acid oxidation method (Wolbach and Anders, 1989), Masiello and Druffel (1998) estimated that 12-31% of SOC in the Northeast Pacific and the Southern Ocean surface sediments was black carbon (BC). However, the dichromate-sulfuric acid oxidation may over-estimate the concentration of BC, because this method is more biased toward modern (char) material (Currie et al., 2002). Alternatively, the BPCA method isolates aromatic components of BC as benzene rings substituted with carboxylic acid groups, and provides structural information about the BC. Recent modifications to the BPCA method by Ziolkowski and Druffel (2009) involve few biases in quantifying BC in the continuum between char and soot in UDOM. Here we use the BPCA method to determine the concentrations and 14C values of BC in sediments from three sites in the Northeast Pacific Ocean. Constraining the difference between non-BC SOC and BC-SOC using the BPCA method allows for a more precise estimate of how much BC is present in the sediments and its 14C age. Presumably, the intermediate reservoir of BC is oceanic dissolved organic carbon (DOC) and is, in part, responsible for DOC’s great 14C age. These results can be utilized to better constrain the oceanic carbon budget as a possible sink of BC. References: Currie, L. A., Benner Jr., B. A., Kessler, J.D., et al (2002), A critical evaluation of interlaboratory data on total, elemental, and isotopic carbon in the carbonaceous particle reference material, nist srm 1649a, J. Res. Natl. Inst. Stand. Technol., 107, 279-298. Masiello, C., and E. R. Druffel (1988), Black carbon in deep-sea sediments, Science, 280, 1911-1913. Wolbach, W., and E. Anders (1989), Elemental carbon in sediments: Determination and isotopic analysis in presence of kerogen, Geochim. Cosmochim. Acta, 53, 1637-1647. Ziolkowski, L. A., and E. R. Druffel (2010), Aged black carbon identified in marine dissolved organic carbon, J. Geophys. Res., 37, L16601, doi: 10.1029/2010GL043963.

Coppola, A. I.; Ziolkowski, L. A.; Druffel, E. R.

2010-12-01

158

Experimental Investigation for the Effect of the Core Length on the Optimum Acid Flux in Carbonate Acidizing  

E-print Network

Matrix acidizing is commonly used to stimulate wells in carbonate reservoirs. Large amounts of lab tests indicate an optimum acid interstitial velocity (Vi-opt, injection rate over flow area and porosity) exists, which results in the minimum volume...

Dong, Kai

2012-10-19

159

The use of 7 LiOH-impregnated filters for the collection of acidic gases and analysis by instrumental neutron activation analysis  

Microsoft Academic Search

A simple system was designed using7LiOH-impregnated filters to collect acidic gases from ambient air and from highly concentrated volcanic plumes or gas streams. These filters were developed for analysis using instrumental neutron activation analysis, but other analytical techniques could be used as well. The sampling system was designed to use a series of 1–3 M7LiOH-impregnated filters to collect high concentrations

David L. Finnegan; Janet P. Kotra; Diane M. Hermann; William H. Zoller

1989-01-01

160

The inhibition of mitochondrial cytochrome oxidase by the gases carbon monoxide, nitric oxide, hydrogen cyanide and hydrogen sulfide: chemical mechanism and physiological significance.  

PubMed

The four gases, nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H(2)S) and hydrogen cyanide (HCN) all readily inhibit oxygen consumption by mitochondrial cytochrome oxidase. This inhibition is responsible for much of their toxicity when they are applied externally to the body. However, recently these gases have all been implicated, to greater or lesser extents, in normal cellular signalling events. In this review we analyse the chemistry of this inhibition, comparing and contrasting mechanism and discussing physiological consequences. The inhibition by NO and CO is dependent on oxygen concentration, but that of HCN and H(2)S is not. NO and H(2)S are readily metabolised by oxidative processes within cytochrome oxidase. In these cases the enzyme may act as a physiological detoxifier of these gases. CO oxidation is much slower and unlikely to be as physiologically important. The evidence for normal physiological levels of these gases interacting with cytochrome oxidase is equivocal, in part because there is little robust data about their steady state concentrations. A reasonable case can be made for NO, and perhaps CO and H(2)S, inhibiting cytochrome oxidase in vivo, but endogenous levels of HCN seem unlikely to be high enough. PMID:18839291

Cooper, Chris E; Brown, Guy C

2008-10-01

161

Origin of nitrogen-rich natural gases in the California Great Valley: Evidence from helium, carbon and nitrogen isotope ratios  

Microsoft Academic Search

Dry natural gases produced from the Sacramento and northern San Joaquin basins contain up to 87% nitrogen. 15 N measurements for gases with N 2 8% vary from 0.9%. to 3.5%.; methane 13 C values vary from -61%. to -15%. 3 He \\/ 4 He ratios indicate the presence of mantle-derived helium in addition to radiogenic crustal helium and suggest

P. D. Jenden; I. R. Kaplan; R. Poreda; H. Craig

1988-01-01

162

Origin of nitrogen-rich natural gases in the California Great Valley: Evidence from helium, carbon and nitrogen isotope ratios  

Microsoft Academic Search

Dry natural gases produced from the Sacramento and northern San Joaquin basins contain up to 87% nitrogen. δ¹⁵N measurements for gases with Nâ ⥠8% vary from 0.9{per thousand} to 3.5{per thousand}; methane δ¹³C values vary from -61{per thousand} to -15{per thousand}. ³He\\/⁴He ratios indicate the presence of mantle-derived helium in addition to radiogenic crustal helium and suggest that the

P. D. Jenden; I. R. Kaplan; R. J. Poreda; H. Craig

1988-01-01

163

Synthesis of acid-functionalized composite via surface deposition of acid-containing amorphous carbon  

NASA Astrophysics Data System (ADS)

A synthetic procedure, including two steps: a hydrothermal treatment using H2SO4 solution and a thermal treatment with concentrated H2SO4 in Teflon-lined stainless autoclaves was developed to synthesize acid-functionalized composite. In this process, the carbonization of glucose which contributed to the formation of carbon species with acid functional groups occurred on the silica surface. The resultant composite, investigated by powder XRD, low temperature N2 sorption and TEM, possessed well-defined mesostructure. And it was determined by XPS that amorphous carbon was deposited at the silica surface of SBA-15. The presence of multi-functional groups in the composite was confirmed by FT-IR results. Furthermore, carboxylic and sulfonic groups could be incorporated into the composite material via the covalent bond. The composite was employed as the catalyst for the acetalization of carbonyl compounds. It was suggested that acid sites were well dispersed, which was responsible for the good performance in the catalytic test. According to these facts, a synthesis route for mesostructured composite with acid functional groups has been proposed.

Du, Bin; Zhang, Xuan; Lou, Lan-Lan; Dong, Yanling; Liu, Gaixia; Liu, Shuangxi

2012-07-01

164

Carbonic Anhydrase 5 Regulates Acid-Base Homeostasis in Zebrafish  

PubMed Central

The regulation of the acid-base balance in cells is essential for proper cellular homeostasis. Disturbed acid-base balance directly affects cellular physiology, which often results in various pathological conditions. In every living organism, the protein family of carbonic anhydrases regulate a broad variety of homeostatic processes. Here we describe the identification, mapping and cloning of a zebrafish carbonic anhydrase 5 (ca5) mutation, collapse of fins (cof), which causes initially a collapse of the medial fins followed by necrosis and rapid degeneration of the embryo. These phenotypical characteristics can be mimicked in wild-type embryos by acetazolamide treatment, suggesting that CA5 activity in zebrafish is essential for a proper development. In addition we show that CA5 regulates acid-base balance during embryonic development, since lowering the pH can compensate for the loss of CA5 activity. Identification of selective modulators of CA5 activity could have a major impact on the development of new therapeutics involved in the treatment of a variety of disorders. PMID:22745834

Postel, Ruben; Sonnenberg, Arnoud

2012-01-01

165

Maintenance Carbon Cycle in Crassulacean Acid Metabolism Plant Leaves 1  

PubMed Central

The reciprocal relationship between diurnal changes in organic acid and storage carbohydrate was examined in the leaves of three Crassulacean acid metabolism plants. It was found that depletion of leaf hexoses at night was sufficient to account quantitatively for increase in malate in Ananas comosus but not in Sedum telephium or Kalanchoë daigremontiana. Fructose and to a lesser extent glucose underwent the largest changes. Glucose levels in S. telephium leaves oscillated diurnally but were not reciprocally related to malate fluctuations. Analysis of isolated protoplasts and vacuoles from leaves of A. comosus and S. telephium revealed that vacuoles contain a large percentage (>50%) of the protoplast glucose, fructose and malate, citrate, isocitrate, ascorbate and succinate. Sucrose, a major constituent of intact leaves, was not detectable or was at extremely low levels in protoplasts and vacuoles from both plants. In isolated vacuoles from both A. comosus and S. telephium, hexose levels decreased at night at the same time malate increased. Only in A. comosus, however, could hexose metabolism account for a significant amount of the nocturnal increase in malate. We conclude that, in A. comosus, soluble sugars are part of the daily maintenance carbon cycle and that the vacuole plays a dynamic role in the diurnal carbon assimilation cycle of this Crassulacean acid metabolism plant. PMID:16664005

Kenyon, William H.; Severson, Ray F.; Black, Clanton C.

1985-01-01

166

Electrochemical Determination of Glycoalkaloids Using a Carbon Nanotubes-Phenylboronic Acid Modified Glassy Carbon Electrode  

PubMed Central

A versatile strategy for electrochemical determination of glycoalkaloids (GAs) was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA) modified glassy carbon electrode. PBA reacts with ?-solanine and ?-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 ?M to 28 ?M and the detection limit was 0.3 ?M. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors. PMID:24287539

Wang, Huiying; Liu, Mingyue; Hu, Xinxi; Li, Mei; Xiong, Xingyao

2013-01-01

167

Corrosion inhibition of aqueous potassium carbonate gas treating systems  

Microsoft Academic Search

Union Carbide Corp.'s new chemical mixture inhibits corrosion of ferrous metals used in acid-gas treating plants that use aqueous potassium carbonate solutions to remove carbon dioxide and hydrogen sulfide from natural gases, flue gases, synthesis gas, etc. The new mixture consists of (1) about 9 to 1 parts by weight of a vanadium compound capable of ionizing in the aqueous

Mago

1976-01-01

168

Sulfuric acid as an agent of carbonate weathering constrained by ? 13C DIC: Examples from Southwest China  

Microsoft Academic Search

Rock weathering by carbonic acid is thought to play an important role in the global carbon cycle because it can geologically sequestrate atmospheric CO2. Current model of carbon cycle evolution usually assumes that carbonic acid is the major weathering agent and that other acids are not important. Here, we use carbon isotopic evidence and water chemistry of springs and rivers

Si-Liang Li; Damien Calmels; Guilin Han; Jérôme Gaillardet; Cong-Qiang Liu

2008-01-01

169

Synthesis of Mixed Acid Anhydrides from Methane and Carbon Dioxide in  

E-print Network

establishes that the primary product is a mixed anhydride of acetic acid and the acid solvent. In sulfuricSynthesis of Mixed Acid Anhydrides from Methane and Carbon Dioxide in Acid Solvents Mark Zerella acid, the overall reaction is CH4 + CO2 + SO3 f CH3C(O)-O-SO3H. Hydrolysis of the mixed anhydride

Bell, Alexis T.

170

The Carbon Isotopic Content and Concentration of Ambient Formic and Acetic Acid  

Microsoft Academic Search

A direct method for source determination of atmospheric formic and acetic acid, through carbon isotopic analysis of the ambient acids and their potential sources, has been successfully developed and tested. These first carbon isotopic measurements of formic acid in the atmosphere were found to be fairly constant, regardless of location. This is consistent with a single dominating source of formic

Bryan Jay Johnson

1991-01-01

171

Preparation and properties of activated carbons prepared from nitric acid treatment of bituminous coal  

Microsoft Academic Search

The preparation and properties of low-ash activated carbons from a Pennsylvania high volatile bituminous coal have been investigated. The conversion of raw coal to such carbon was carried out in three steps: The oxidation of the raw coal to humic acids by air and nitric acid followed by separation of the mineral matter with solvent extraction of the acids; the

E. S. Tomezko; T. S. Polansky

1961-01-01

172

Poly(carbonate ester)s Based on Units of 6-Hydroxyhexanoic Acid and Glycerol  

E-print Network

Poly(carbonate ester)s Based on Units of 6-Hydroxyhexanoic Acid and Glycerol Jesse B. Wolinsky(trimethylene carbon- ate), and most notably poly(glycolic acid) and poly(lactic acid), have met wide acceptance- and nanoparticles for drug delivery applications.5-8 When a polymer does not meet the requirements for an intended

173

Activated carbons treated with sulphuric acid: Catalysts for catalytic wet peroxide oxidation  

Microsoft Academic Search

Different liquid phase thermal treatments were applied to a commercial activated carbon (Norit ROX 0.8) in order to produce modified activated carbons with varying surface chemistry and increased acidic character. Chemical characterization of the prepared materials includes determination of the point of zero charge and evaluation of the concentration and nature of acidic and basic surface functionalities by acid\\/base titrations

Helder T. Gomes; Sandra M. Miranda; Maria J. Sampaio; Adrián M. T. Silva; Joaquim L. Faria

2010-01-01

174

Boric acid corrosion of carbon and low alloy steels  

SciTech Connect

Leakage of borated water from the reactor coolant system of pressurized water reactors (PWRs) and the resulting corrosion of carbon and low alloy steel components are concerns that have been addressed by utilities for many years. Significant corrosion has been observed in instances where such leakage has gone undetected for several months. In 1990, the B and W Owners Group (B and WOG) sponsored a test program to determine the levels of wastage that are possible when primary water leakage occurs. In this test program, carbon and stainless steel specimens were exposed to borated water at temperatures from 300 F to 550 F. Initial boric acid concentration was controlled within the limits of 13,000 to 15,000 ppm (as H{sub 3}BO{sub 3}) with 1.0--2.0 ppm lithium (as LiOH) added to duplicate the primary water chemistry. Testing was performed to determine the degree of attack caused by a leak traveling along a pipe both with and without insulation. These tests show the importance of temperature and boric acid concentrations on the wastage that can occur from such a leak.

Campbell, C.A.; Fyfitch, S. [B and W Nuclear Technologies, Lynchburg, VA (United States); Martin, D.T. [Babcock and Wilcox, Alliance, OH (United States). Research and Development Division

1994-12-31

175

Electrochemical detection of amino acids at carbon nanotube and nickel-carbon nanotube modified electrodes.  

PubMed

The oxidation and enhanced detection of traditionally 'non-electroactive' amino acids at a single-wall carbon nanotube (SWNT) surface and at a nickel hydroxide film electrochemically deposited and generated upon the SWNT layer is reported. Different CNT are compared, with Nafion-dispersed SWNT offering the most favorable layer for constant-potential amperometric detection. Factors affecting the oxidation process, including the pH or applied potential, are assessed. The response of the SWNT-Nafion coated electrode compares favorably with that of copper and nickel disk electrodes under flow injection analysis (FIA) conditions. The electrodeposition of nickel onto the SWNT-Nafion layer (Ni-CNT) led to a dramatic enhancement of the analytical response (vs. that observed at the SWNT or nickel electrodes alone). The oxidative process at the Ni(OH)(2) layer has been studied and the increase in sensitivity rationalized. In the presence of amino acid the Ni-CNT layer undergoes an electrocatalytic process in which the amino acid reduces the newly formed NiO(OH) species. Furthermore, the attractive response of both the CNT and Ni-CNT layers has allowed these electrodes to be used for constant-potential FIA of various amino acids and indicates great promise for monitoring chromatographic effluents. Once again an improved signal was observed at the Ni-CNT electrode compared to nickel deposited upon a bare glassy carbon electrode (Ni-GC). PMID:15508037

Deo, Randhir P; Lawrence, Nathan S; Wang, Joseph

2004-11-01

176

Online measurements of ammonia, acidic trace gases and aerosol inorganic ionic species in the Amazon Basin under biomass burning and background conditions  

NASA Astrophysics Data System (ADS)

We have measured diurnal and seasonal variations in the mixing ratios of ammonia (NH_3), nitric acid (HNO_3), nitrous acid (HNO_2), hydrochloric acid (HCl) and water-soluble inorganic aerosol species as ammonium (NH4+), nitrate (NO3-), nitrite (NO2-), chloride (Cl_-) and sulfate (SO_42-) on a pasture site in the Amazon Basin (Rondônia, Brazil) from September to November 2002 (LBA-SMOCC). Sampling was performed using a wet-annular denuder in combination with a Steam-Jet Aerosol Collector (SJAC) followed by online analysis using a mobile ion chromatograph for anions and flow injection analysis for ammonium. Measurements were supported by monitoring of meteorological parameters (e.g., relative humidity, air temperature, wind speed). Results from the biomass burning season, transition period and wet season will be presented. Preliminary evaluations show that ammonia levels were found to be highest (median values of 2.0 ppb during the biomass burning season), whereas median values for acidic trace gases were found to be an order of magnitude lower (0.2 ppb for nitric acid and 0.14 ppb for hydrochloric acid under biomass burning conditions). Preliminary results of aerosol species show that the mixing ratios were highest during the burning season (median values for ammonium ? 1.0 ppb, for nitrate ? 0.3 ppb, for nitrite ? 0.05 ppb, for chloride ? 0.1 ppb and for sulfate ? 0.25 ppb). The calculated median mixing ratio levels decreased steadily from the biomass burning season through the transition period to the wet season, by approximately 75% for trace gases and by 50% and 75% for aerosol ammonium and other inorganic aerosol species respectively. We found a strong dependence of ammonia, nitric acid, and aerosol ammonium nitrate on meteorological parameters (especially air temperature and relative humidity) as well as on daily/ nocturnal boundary layer conditions during day and night time. The diurnal data sets suggest that evaporation of ammonia and nitric acid from the aerosol surface contributes effectively to increased mixing ratios in the turbulent boundary layer at day time. Additionally, we found that a sharp increase of relative humidity to nearly 100% and a decrease of temperature from day to night time promotes the formation of aerosol ammonium nitrate due to gas-aerosol interactions. Both the soluble inorganic ionic species and soluble gases, such as NH_3 and HNO_3, are expected to play a major role in the nucleation and growth of cloud droplets under clean and polluted conditions.

Trebs, I.; Meixner, F. X.; Otjes, R. P.; Slanina, J. J.; Jongejan, P. A. C.; Moura, M. A. L.; da Silva, R. S., Jr.; Mayol-Bracero, O. L.; Artaxo, P.; Andreae, M. O.

2003-04-01

177

Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids  

PubMed Central

The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode. PMID:21711910

2011-01-01

178

Simultaneous determination of ascorbic acid, uric acid and neurotransmitters with a carbon ceramic electrode prepared by sol-gel technique.  

PubMed

A sol-gel carbon composite electrode (CCE) has been prepared by mixing a sol-gel precursor (e.g. methyltrimethoxysilane) and carbon powder without adding any electron transfer mediator or specific reagents. It was demonstrated that this sensor can be used for simultaneous determination ascorbic acid, neurotransmitters (dopamine and adrenaline) and uric acid. Direct electrochemical oxidation of ascorbic acid, uric acid and catecholamines at a carbon composite electrode was investigated. The experimental results were compared with other common carbon based electrodes, specifically, boron doped diamond, glassy carbon, graphite and carbon paste electrodes. It was found that the CCE shows a significantly higher of reversibility for dopamine. In addition, in comparison to the other electrodes used, for CCE the oxidation peaks of uric acid, ascorbic acid and catecholamines in cyclic and square wave voltammetry were well resolved at the low positive potential with good sensitivity. The advantages of this sensor were high sensitivity, inherent stability and simplicity and ability for simultaneous determination of uric acid, catecholamines and ascorbic acid without using any chromatography or separation systems. The analytical performance of this sensor has been evaluated for detection of biological molecules in urine and serum as real samples. PMID:18970846

Salimi, Abdollah; Mamkhezri, Hussein; Hallaj, Rahman

2006-11-15

179

Voluntary Reporting of Greenhouse Gases  

EIA Publications

The Voluntary Reporting of Greenhouse Gases Program was suspended May 2011. It was a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., could report to the Energy Information Administration, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

2011-01-01

180

Morphology and acid–base properties of porous carbon derived from poly(ethylene terephthalate) by nitric acid treatment  

Microsoft Academic Search

Activated carbon prepared from poly(ethylene terephthalate) was treated with nitric acid at ambient temperature and at the boiling point of the suspension. The morphology of the products was investigated by scanning electron microscopy, nitrogen adsorption observations and by small-angle X-ray scattering. The effect of acidic treatment on acid–base surface properties was studied by quasi-equilibrium potentiometric acid–base titration. It is found

K. László; Katalin Marthi; E. Tombácz; E. Geissler

181

Production and characterization of methyl ester sophorolipids with 22-carbon-fatty acids  

Microsoft Academic Search

In this study, various fatty acids of 18 and 22 carbons were used as substrates to produce sophorolipids in Candida bombicola ATCC 22214. Methyl esterification of erucic acid and C22-enriched rapeseed oil generated mainly acidic sophorolipids with different degrees of saturation in the fatty acid chain, which was demonstrated by structural analysis using HPLC, LC–MS and NMR spectroscopy. Regardless of

Jae Dong Shin; Jeongmi Lee; Yong Bum Kim; In-sun Han; Eun-Ki Kim

2010-01-01

182

Carbon and hydrogen isotopic characteristics of natural gases from the Luliang and Baoshan basins in Yunnan Province, China  

Microsoft Academic Search

The Luliang and Baoshan basins of Yunnan Province are two small-sized continental oil\\/gas-bearing sedimentary basins, which\\u000a were developed at the bases of the Carboniferous and Devonian systems during the Late Tertiary, covering an area of 325 km2 and 254 km2, respectively. Since the 1990s, there have been discovered small-sized natural gas pools in these two basins. The natural\\u000a gases are

Yongchang Xu; Wenhui Liu; Ping Shen; Wanchun Wang; Xiaofeng Wang; Tenger; Yaomin Yan; Ruobin Liu

2006-01-01

183

Sorption of boric acid and borax by activated carbon impregnated with various compounds  

Microsoft Academic Search

The separation of boron compounds, boric acid and borax from aqueous solution by activated carbon before and after impregnation with various compounds was studied. A series of activated carbons was prepared from coconut shell impregnated with calcium and barium chlorides, citric and tartaric acids. The examined processes were performed in batch and continuous systems under equilibrium and dynamic conditions. Impregnation

Lj. V. Rajakovi?; M. Dj. Risti?

1996-01-01

184

Interaction of nucleic acids with carbon nanotubes and dendrimers.  

PubMed

Nucleic acid interaction with nanoscale objects like carbon nanotubes (CNTs) and dendrimers is of fundamental interest because of their potential application in CNT separation, gene therapy and antisense therapy. Combining nucleic acids with CNTs and dendrimers also opens the door towards controllable self-assembly to generate various supra-molecular and nano-structures with desired morphologies. The interaction between these nanoscale objects also serve as a model system for studying DNA compaction, which is a fundamental process in chromatin organization. By using fully atomistic simulations, here we report various aspects of the interactions and binding modes of DNA and small interfering RNA (siRNA) with CNTs, graphene and dendrimers. Our results give a microscopic picture and mechanism of the adsorption of single- and double-strand DNA (ssDNA and dsDNA) on CNT and graphene. The nucleic acid-CNT interaction is dominated by the dispersive van der Waals (vdW) interaction. In contrast, the complexation of DNA (both ssDNA and dsDNA) and siRNA with various generations of poly-amido-amine (PAMAM) dendrimers is governed by electrostatic interactions. Our results reveal that both the DNA and siRNA form stable complex with the PAMAM dendrimer at a physiological pH when the dendrimer is positively charged due to the protonation of the primary amines. The size and binding energy of the complex increase with increase in dendrimer generation. We also give a summary of the current status in these fields and discuss future prospects. PMID:22750983

Nandy, Bidisha; Santosh, Mogurampelly; Maiti, Prabal K

2012-07-01

185

USE OF THE COMPOSITION AND STABLE CARBON ISOTOPE RATIO OF MICROBIAL FATTY ACIDS TO STUDY CARBON CYCLING  

EPA Science Inventory

We use measurements of the concentration and stable carbon isotopic ratio (Gamma 13C) of individual microbial phospholipid fatty acids (PLFAS) in soils and sediments as indicators of live microbial biomass levels and microbial carbon source. For studies of soil organic matter (SO...

186

USE OF STABLE CARBON ISOTOPE RATIOS OF FATTY ACIDS TO EVALUATE MICROBIAL CARBON SOURCES IN TERRESTRIAL ENVIRONMENTS  

EPA Science Inventory

We use measurements of the concentration and stable carbon isotopic ratio (D 13C) of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels and microbial carbon source. We found that intensive sugar cane cultivation leads to ...

187

Real-time measurements of ammonia, acidic trace gases and water-soluble inorganic aerosol species at a rural site in the Amazon Basin  

NASA Astrophysics Data System (ADS)

We measured the mixing ratios of ammonia (NH3), nitric acid (HNO3), nitrous acid (HONO), hydrochloric acid (HCl), sulfur dioxide (SO2) and the corresponding water-soluble inorganic aerosol species, ammonium (NH4+), nitrate (NO3-), nitrite (NO2-), chloride (Cl-) and sulfate (SO42-), and their diel and seasonal variations at a pasture site in the Amazon Basin (Rondônia, Brazil). This study was conducted within the framework of LBA-SMOCC (Large Scale Biosphere Atmosphere Experiment in Amazonia Smoke Aerosols, Clouds, Rainfall and Climate). Sampling was performed from 12 September to 14 November 2002, extending from the dry season (extensive biomass burning activity), through the transition period to the wet season (background conditions). Measurements were made continuously using a wet-annular denuder in combination with a Steam-Jet Aerosol Collector (SJAC) followed by suitable on-line analysis. A detailed description and verification of the inlet system for simultaneous sampling of soluble gases and aerosol compounds is presented. Overall measurement uncertainties of the ambient mixing ratios usually remained below 15%. The limit of detection (LOD) was determined for each single data point measured during the field experiment. Median LOD values (3?-definition) were ?0.015 ppb for acidic trace gases and aerosol anions and ?0.118 ppb for NH3 and aerosol NH4+. Mixing ratios of acidic trace gases remained below 1ppb throughout the measurement period, while NH3 levels were an order of magnitude higher. Accordingly, mixing ratios of NH4+ exceeded those of other inorganic aerosol contributors by a factor of 4 to 10. During the wet season, mixing ratios decreased by nearly a factor of 3 for all compounds compared to those observed when intensive biomass burning took place. Additionally, N-containing gas and aerosol species featured pronounced diel variations. This is attributed to strong relative humidity and temperature variations between day and night as well as to changing photochemistry and stability conditions of the planetary boundary layer. HONO exhibited a characteristic diel cycle with high mixing ratios at nighttime and was not completely depleted by photolysis during daylight hours.

Trebs, I.; Meixner, F. X.; Slanina, J.; Otjes, R.; Jongejan, P.; Andreae, M. O.

2004-02-01

188

Separation of gases through gas enrichment membrane composites  

DOEpatents

Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

Swedo, Raymond J. (Mt. Prospect, IL); Kurek, Paul R. (Schaumburg, IL)

1988-01-01

189

Separation of gases through gas enrichment membrane composites  

DOEpatents

Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

Swedo, R.J.; Kurek, P.R.

1988-07-19

190

The rate of carbonic acid decomposition in sea water and its oceanographic significance  

E-print Network

with and without the influence of atmospheric carbon dioxide based upon Buch's tables on the carbon dioxide and boric acid system in sea water are compared with exper- imental data obtained by the method of Mitchell and Rakestraw(1933) and Stoddard (1952... Mixtures of weak acids and their salts or of weak bases and their sa3ts are called buffer solutions, since they resist a change in pH upon addit1on oi' sli~ht amounts oi' acid or bases (Kolthoff', 1949). Sea water contairs carbonic and boric acids...

Park, Kilho

2012-06-07

191

Novel graphene flowers modified carbon fibers for simultaneous determination of ascorbic acid, dopamine and uric acid.  

PubMed

A novel and sensitive carbon fiber electrode (CFE) modified by graphene flowers was prepared and used to simultaneously determine ascorbic acid (AA), dopamine (DA) and uric acid (UA). SEM images showed that beautiful and layer-petal graphene flowers homogeneously bloomed on the surface of CFE. Moreover, sharp and obvious oxidation peaks were found at the obtained electrode when compared with CFE and glassy carbon electrode (GCE) for the oxidation of AA, DA and UA. Also, the linear calibration plots for AA, DA and UA were observed, respectively, in the ranges of 45.4-1489.23 ?M, 0.7-45.21 ?M and 3.78-183.87 ?M in the individual detection of each component. By simultaneously changing the concentrations of AA, DA and UA, their oxidation peaks appeared at -0.05 V, 0.16 V and 2.6 V, and the good linear responses ranges were 73.52-2305.53 ?M, 1.36-125.69 ?M and 3.98-371.49 ?M, respectively. In addition, the obtained electrode showed satisfactory results when applied to the determination of AA, DA and UA in urine and serum samples. PMID:24140872

Du, Jiao; Yue, Ruirui; Ren, Fangfang; Yao, Zhangquan; Jiang, Fengxing; Yang, Ping; Du, Yukou

2014-03-15

192

Distribution of dicarboxylic acids and carbon isotopic compositions in aerosols from 1997 Indonesian forest fires  

Microsoft Academic Search

Fine aerosol particles collected in Southeast Asia during 1997 Indonesian forest fires were studied for the concentrations of total carbon (TC), water-soluble organic carbon (WSOC) and low molecular weight dicarboxylic acids (C2-C12) as well as carbon isotopic ratios of TC (delta13CTC). TC and WSOC showed a large increase during the heavy forest fire event. At the same period, dicarboxylic acids,

M. Narukawa; K. Kawamura; N. Takeuchi; T. Nakajima

1999-01-01

193

Simultaneous determination of dopamine, ascorbic acid, and uric acid using carbon ionic liquid electrode.  

PubMed

A recently constructed carbon composite electrode using room temperature ionic liquid as pasting binder was employed as a novel electrode for sensitive, simultaneous determination of dopamine (DA), ascorbic acid (AA), and uric acid (UA). The apparent reversibility and kinetics of the electrochemical reaction for DA, AA, and UA found were improved significantly compared to those obtained using a conventional carbon paste electrode. The results show that carbon ionic liquid electrode (CILE) reduces the overpotential of DA, AA, and UA oxidation, without showing any fouling effect due to the deposition of their oxidized products. In the case of DA, the oxidation and reduction peak potentials appear at 210 and 135mV (vs Ag/AgCl, KCl, 3.0M), respectively, and the CILE shows a significantly better reversibility for dopamine. The oxidation peak due to the oxidation of AA occurs at about 60mV. For UA, a sharp oxidation peak at 340mV and a small reduction peak at 250mV are obtained at CILE. Differential pulse voltammetry was used for the simultaneous determination of ternary mixtures of DA, AA, and UA. Relative standard deviation for DA, AA, and UA determinations were less than 3.0% and DA, AA, and UA can be determined in the ranges of 2.0x10(-6)-1.5x10(-3), 5.0x10(-5)-7.4x10(-3), and 2.0x10(-6)-2.2x10(-4)M, respectively. The method was applied to the determination of DA, AA, and UA in human blood serum and urine samples. PMID:17069745

Safavi, Afsaneh; Maleki, Norouz; Moradlou, Omran; Tajabadi, Fariba

2006-12-15

194

Fate of microbial nitrogen, carbon, hydrolysable amino acids, monosaccharides, and fatty acids in sediment  

NASA Astrophysics Data System (ADS)

The fate of microbial carbon, nitrogen, hydrolysable amino acids (HAAs), monosaccharides, and fatty acids in sediment was investigated experimentally. The microbial community of a tidal flat sediment was labeled with 13C-enriched glucose and 15N-enriched ammonium, and sediment was incubated for up to 371 days. Analysis of total concentrations and 13C- and 15N content of bulk sediment, hydrolysable amino acids (including D-alanine), monosaccharides, total fatty acids (TFAs), and phospholipid-derived fatty acids (PLFAs) allowed us to trace the fate of microbial biomass and -detritus and the major biochemical groups therein (proteins, carbohydrates, and lipids) over intermediate time scales (weeks-months). Moreover, the unidentified fraction of the labeled material (i.e. not analyzed as HAA, FA, or carbohydrate) provided information on the formation and fate of molecularly uncharacterizable organic matter. Loss of 13C and 15N from the sediment was slow (half live of 433 days) which may have been due to the permanently anoxic conditions in the experiment. Loss rates for the different biochemical groups were also low with the following order of loss rate constants: PLFA > TFA > HAA > monosaccharides. The unidentified 13C-pool was rapidly formed (within days) and then decreased relatively slowly, resulting in a gradual relative accumulation of this pool over time. Degradation and microbial reworking of the labeled material resulted in subtle, yet consistent, diagenetic changes within the different biochemical groups. In the HAA pool, glycine, lysine, and proline were lost relatively slowly (i.e. best preserved) while there was no accumulation of D-alanine relative to L-alanine, indicating no relative accumulation of bacterial macromolecules rich in D-alanine. In the fatty acid pool, there was very little difference between PLFAs and TFAs, indicating a very similar lability of these pools. Differences between individual fatty acids included a relatively slow loss of i15:0, ai15:0 and 18:1?7c which likely resulted from production of these bacterial fatty acids during bacterial reworking of the organic matter. Differences between loss rate constants for individual monosaccharides were not significant. An exception was ribose that was produced and lost relatively rapidly, which may be related to ribose being an important component of RNA. Losses of bulk 13C and 15N were closely coupled despite partly being present in different biochemicals and partly being derived from different microbial sources, indicating no selective preservation of either C or N during organic matter diagenesis.

Veuger, Bart; van Oevelen, Dick; Middelburg, Jack J.

2012-04-01

195

Geochemical monitoring of the 2002 2003 eruption at Stromboli volcano (Italy): precursory changes in the carbon and helium isotopic composition of fumarole gases and thermal waters  

NASA Astrophysics Data System (ADS)

Significant changes in the helium and carbon isotopic composition of shallow thermal waters vs. gas and a crater fumarolic gas have been recorded at Stromboli prior and during the 2002 2003 eruption. The3He/4He ratios corrected for air contamination (Rc/Ra), and ?13C of fumarolic gases gradually increased from May to November 2002 before the eruption onset. These variations imply early degassing of a gas-rich magma at depth that likely fed both the intense Strombolian activity and small lava overflows recorded during that period. The lava effusion of late December 2002 was shortly preceded by a marked Rc/Ra decrease both in water and fumarolic gases. Comparison of He/CO2 and CH4/CO2 ratios in dissolved gas and with{? }^{13} C_{CO_2 } values rules out the Rc/Ra decrease due to an increasing input of radiogenic4He. The Rc/Ra decrease is attributed to the He isotope fractionation during rapid magma ascent and degassing. A new uprising of 3He-rich magma probably occurred in January to February 2003, when Rc/Ra ratios displayed the highest values in dissolved gases ever measured before (4.56 Rc/Ra). The increase in He/CO2 and CH4/CO2 ratios and decrease in ?13C of dissolved CO2 was recorded after the 5 April 2003 explosive paroxysm, likely caused by enhanced gas-water interaction inducing CO2 dissolution. No anomalous Rc/Ra values were recorded in the same period, when usual Strombolian activity gradually resumed.

Capasso, G.; Carapezza, M. L.; Federico, C.; Inguaggiato, S.; Rizzo, A.

2005-12-01

196

Energy gases - the methane age and beyond  

Microsoft Academic Search

The combustion of fossil fuels results in the emissions of gases and pollutants that produce adverse ecological effects. Evidence is also accumulating that suggests they may also cause global climate change. The combustion gases that are connected with global climate change are primarily carbon dioxide (CO[sub 2]) and to a lesser degree methane (CH[sub 4]). All of these gases already

Nakicenovic

1993-01-01

197

Toxicity of pyrolysis gases from polypropylene  

NASA Technical Reports Server (NTRS)

A sample of polypropylene was evaluated for toxicity of pyrolysis gases, using the toxicity screening test method developed at the University of San Francisco. The gases from this sample appeared to be equivalent or less toxic than the gases from a sample of polyethylene under these particular test conditions. Carbon monoxide appeared to be the principal toxicant.

Hilado, C. J.; Schneider, J. E.; Brauer, D. F.

1979-01-01

198

Novel platinum-tin oxide-silicon nitride-silicon dioxide-silicon gas sensing component for oxygen and carbon monoxide gases at low temperature  

NASA Astrophysics Data System (ADS)

A novel gas sensing component based on a platinum-tin oxide-silicon nitride-silicon dioxide-silicon metal-insulator-semiconductor (MIS) capacitor has been developed. The new approach to integrate the catalytic properties of platinum (Pt) and the gas sensing properties of tin oxide (SnOx) with the surface-sensitive silicon MIS capacitor enhances the gas detection at lower temperature. The device is capable of detecting oxygen (O2) and carbon monoxide (CO) gases at room ambient and at temperature much lower than the operating temperature of the conventional solid state gas detectors. The gas sensing characteristics of the device and its detection mechanism for O2 and CO at 27-100 °C are presented.

Kang, W. P.; Kim, C. K.

1993-07-01

199

Influences of pyrolysis condition and acid treatment on properties of durian peel-based activated carbon.  

PubMed

Durian peel was used for the synthesis of activated carbon used for adsorption of Basic Green 4 dye. Activated carbon was synthesised under either nitrogen (N(2)) atmospheric or vacuum pyrolysis, followed by carbon dioxide (CO(2)) activation. The synthesised activated carbon then was treated with hydrochloric acid (HCl) solution. The results showed that activated carbon synthesised under vacuum pyrolysis exhibited better properties and adsorption capacities than that under nitrogen atmospheric pyrolysis. The HCl treatment improved properties and adsorption capacities of activated carbons. Pseudo-second-order kinetics well described the adsorption of Basic Green 4. PMID:19695874

Nuithitikul, Kamchai; Srikhun, Sarawut; Hirunpraditkoon, Samorn

2010-01-01

200

Atmospheric gases  

NSDL National Science Digital Library

Which gases make up the atmosphere? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the gaseous components of the atmosphere. Students explore the main gases of the atmosphere using a pop-up pie chart. Descriptions of the gases and their percentages in the atmosphere are provided. Students read about water vapor in the atmosphere, and an animation shows a simplified process of precipitation. A pop-up window explains the effects of dust on the atmosphere, and a photograph shows how large amounts of dust in the atmosphere create the reds and oranges displayed in sunsets. Finally, ozone is introduced to students as a necessary component of human life on Earth. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

201

Effect of surface acidic oxides of activated carbon on adsorption of ammonia.  

PubMed

The influence of surface acidity of activated carbon (AC) was experimentally studied on adsorption of ammonia (NH(3)). Coconut shell-based AC was modified by various acids at different concentrations. There were five different acids employed to modified AC, which included nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, and acetic acid. Acidic functional groups on the surface of ACs were determined by a Fourier transform infrared spectrograph (FTIR) and by the Boehm titration method. Specific surface area and pore volume of the ACs were measured by a nitrogen adsorption apparatus. Adsorption amounts of NH(3) onto the ACs were measured by a dynamic adsorption system at room temperature according to the principle of the ASTM standard test method. The concentration of NH(3) in the effluent stream was monitored by a gas-detecting tube technique. Experimental results showed that adsorption amounts of NH(3) on the modified ACs were all enhanced. The ammonia adsorption amounts on various activated carbons modified by different acids are in the following order: nitric acid>sulfuric acid>acetic acid approximately phosphoric acid>hydrochloric acid. It is worth to note that the breakthrough capacity of NH(3) is linearly proportional to the amount of acidic functional groups of the ACs. PMID:18403110

Huang, Chen-Chia; Li, Hong-Song; Chen, Chien-Hung

2008-11-30

202

Fiscal Year 1998 Annual Report, Carbon Dioxide Information Analysis Center, World Data Center -- A for Atmospheric Trace Gases  

SciTech Connect

Once again, the most recent fiscal year was a productive one for the Carbon Dioxide Information Analysis Center (CDIAC) at Oak Ridge National Laboratory (ORNL), as well as a year for change. The FY 1998 in Review section in this report summarizes quite a few new and updated data and information products, and the ''What's Coming in FY 1999'' section describes our plans for this new fiscal year. During FY 1998, CDIAC began a data-management system for AmeriFlux, a long-term study of carbon fluxes between the terrestrial biosphere of the Western Hemisphere and the atmosphere. The specific objectives of AmeriFlux are to establish an infrastructure for guiding, collecting, synthesizing, and disseminating long-term measurements of CO{sub 2}, water, and energy exchange from a variety of ecosystems; collect critical new information to help define the current global CO{sub 2} budget; enable improved predictions of future concentrations of atmospheric CO{sub 2}; and enhance understanding of carbon fluxes. Net Ecosystem Production (NEP), and carbon sequestration in the terrestrial biosphere. The data-management system, available from CDIAC'S AmeriFlux home page (http://cdiac.esd.ornl.gov/programs/ameriflux/ ) is intended to provide consistent, quality-assured, and documented data across all AmeriFlux sites in the US, Canada, Costa Rica, and Brazil. It is being developed by Antoinette Brenkert and Tom Boden, with assistance from Susan Holladay (who joined CDIAC specifically to support the AmeriFlux data-management effort).

Cushman, R.M.; Boden, T.A.; Hook, L.A.; Jones, S.B.; Kaiser, D.P.; Nelson, T.R.

1999-03-01

203

A tabulation of meterorological variables and concentrations of helium, carbon dioxide, oxygen, and nitrogen in soil gases collected regularly from four sites at the Roosevelt Hot Springs Known Geothermal Resources Area, Utah  

Microsoft Academic Search

A U.S. Geological Survey report is presented giving a tabulation of meterorological variables and concentrations of helium, carbon dioxide, oxygen, and nitrogen in soil gases collected regularly from four sites at the Roosevelt Hot Springs Known Geothermal Resources Area, Utah.

Hinkle

1989-01-01

204

Teacher's Resource Book for Balloons and Gases. Grade 6. Revised. Anchorage School District Elementary Science Program.  

ERIC Educational Resources Information Center

This resource book introduces sixth-grade children to the physical and chemical properties of gases. The unit begins with an investigation of acids and bases. Students then generate carbon dioxide, oxygen, and hydrogen, and investigate the properties of each. The unit culminates with an activity involving an unknown gas. Students conduct tests to…

Anchorage School District, AK.

205

Sulfonated mesoporous silica-carbon composites and their use as solid acid catalysts  

NASA Astrophysics Data System (ADS)

The synthesis of highly functionalized porous silica-carbon composites made up of sulfonic groups attached to a carbon layer coating the pores of three types of mesostructured silica (i.e. SBA-15, KIT-6 and mesocellular silica) is presented. The synthesis procedure involves the following steps: (a) removal of the surfactant, (b) impregnation of the silica pores with a carbon precursor, (c) carbonization and (d) sulfonation. The resulting silica-carbon composites contain ˜30 wt % of carbonaceous matter with a high density of acidic groups attached to the deposited carbon (i.e.sbnd SO3H, sbnd COOH and sbnd OH). The structural characteristics of the parent silica are retained in the composite materials, which exhibit a high surface area, a large pore volume and a well-ordered porosity made up uniform mesopores. The high density of the sulfonic groups in combination with the mesoporous structure of the composites ensures that a large number of active sites are easily accessible to reactants. These sulfonated silica-carbon composites behave as eco-friendly, active, selective, water tolerant and recyclable solid acids. In this study we demonstrate the usefulness of these composites as solid acid catalysts for the esterification of maleic anhydride, succinic acid and oleic acid with ethanol. These composites exhibit a superior intrinsic catalytic activity to other commercial solid acids such as Amberlyst-15.

Valle-Vigón, Patricia; Sevilla, Marta; Fuertes, Antonio B.

2012-11-01

206

Biosynthesis of delta-aminolevulinic acid from the intact carbon skeleton of glutamic acid in greening barley.  

PubMed Central

The customary route in animals and bacteria for delta-aminolevulinic acid biosynthesis is from glycine and succinyl CoA, catalyzed by the enzyme delta-aminolevulinic acid synthetase [succinyl-CoA:glycine C-succinyltransferase (decarboxylating), EC 2.3.1.37]. Attempts to demonstrate this route in plants have been unsuccessful. Evidence is given for a new enzymic route of synthesis of delta-aminolevulinic acid in plants. This route involves the incorporation of the intact five-carbon skeleton of glutamic acid into delta-aminolevulinic acid. Demonstration of the new pathway in plants has been made by feeding specifically labeled [14C]glutamic acid to etiolated barley shoots greening in the light. In the presence of levulinate, a competitive inhibitor of delta-aminolevulinic acid dehydrastase [porphobilinogen synthase; delta-aminolevulinate hydro-lyase (adding delta-aminolevulinate and cyclizing); EC 4.2.1.24], delta-aminolevulinate accumulates. The delta-aminolevulinate formed was chemically degraded by periodate to formaldehyde and succinic acid. The C5 (formaldehyde) fragment was separated, as the 5,5-dimethyl-1,3-cyclohexanedione (dimedone) derivative, from the C1-C4 (succinic acid) fragment. The C5 atom contained radioactivity predominantly derived from C1 of glutamic acid. Conversely, the labeled C3 and C4 atoms of glutamic acid were found primarily in the succinic acid (C1-C4) fragment of delta-aminolevulinate. This labeling pattern for delta-aminolevulinic acid is consistent with a biosynthetic route utilizing the intact five-carbon skeleton of alpha-ketoglutarate, glutamate, or glutamine, and is inconsistent with the delta-aminolevulinic acid synthetase pathway utilizing glycine and succinyl CoA as precursors. PMID:1058487

Beale, S I; Gough, S P; Granick, S

1975-01-01

207

Electron microscopy of carbonaceous matter in Allende acid residues  

NASA Technical Reports Server (NTRS)

On the basis of characteristic diffuse ring diffraction patterns, much of the carbonaceous matter in a large suite of Allende acid residues has been identified as a variety of turbostratic carbon. Crystallites of this phase contain randomly stacked sp(2) hybridized carbon layers and diffraction patterns resemble those from carbon black and glassy carbon. Carbynes are probably absent, and are certainly restricted to less than 0.5% of these acid residues. The work of Ott et al. (1981) provides a basis for the possibility that turbostratic carbon is a carrier of noble gases, but an additional component - amorphous carbon - may be necessary to explain the high release temperatures of noble gases as well as the glassy character of many of the carbonaceous particles. Carbynes are considered to be questionable as important carriers of noble gases in the Allende acid residues.

Lumpkin, G. R.

1982-01-01

208

Modeling the absorption of weak electrolytes and acid gases with ionic liquids using the soft-SAFT approach.  

PubMed

In this work, the solubility of three common pollutants, SO(2), NH(3), and H(2)S, in ionic liquids (ILs) is studied using the soft-SAFT equation of state with relatively simple models. Three types of imidazolium ionic liquids with different anions are described in a transferable manner using the recently published molecular models (Andreu, J. S.; Vega, L. F. J. Phys. Chem. C 2007, 111, 16028; Llovell et al. J. Phys. Chem. B 2011, 115, 4387), whereas new models for SO(2), NH(3), and H(2)S are proposed here. Alkyl-imidazolium ionic liquids with the [PF(6)](-) and [BF(4)](-) anions are considered to be Lennard-Jones chainlike molecules with one associating site in each molecule describing the specific cation-anion interactions. Conversely, the cation and anion forming the imidazolium [Tf(2)N](-) ionic liquids are modeled as a single molecule with three associating sites, taking into account the delocalization of the anion electric charge due to the presence of oxygen groups surrounding the nitrogen of the anion. NH(3) is described with four associating sites: three sites of type H mimicking the hydrogen atoms and one site of type e representing the lone pair of electrons. H(2)S is modeled with three associating sites: two for the sites of type H for the hydrogen atoms and one site of type e for the electronegativity of the sulfur. SO(2) is modeled with two sites, representing the dipole moment of the molecule as an associative interaction. Soft-SAFT calculations with the three models for the pollutants provide very good agreement with the available phase equilibria, enthalpy of vaporization, and heat capacity experimental data. Then, binary mixtures of these compounds with imidazolium-based ionic liquids were calculated in an industrially relevant temperature range. Unlike association interactions between the ionic liquids and the pollutant gases have been explicitly accounted for using an advanced association scheme. A single temperature independent energy binary parameter is sufficient to describe every family of mixtures in good agreement with the available data in the literature. In addition, a vapor-liquid-liquid equilibrium (VLLE) region, never measured experimentally, has been identified for mixtures of hydrogen sulfide + imidazolium ionic liquids with the [PF(6)](-) anion at high H(2)S concentrations. This work illustrates that relatively simple models are able to capture the phase absorption diagram of different gases in ionic liquids, provided accurate models are available for the pure components as well as an accurate equation of state to model the behavior of complex systems. PMID:22663142

Llovell, F; Marcos, R M; MacDowell, N; Vega, L F

2012-07-01

209

Measurement of fossil fuel derived carbon dioxide and other anthropogenic trace gases above Sacramento, California in Spring 2009  

Microsoft Academic Search

Direct quantification of fossil fuel CO2 (CO2ff) in atmospheric samples can be used to examine several carbon cycle and air quality questions. We collected in-situ CO2, CO, and CH4 measurements and flask samples in the boundary layer and free troposphere over Sacramento, California, USA, during two aircraft flights over and downwind of this urban area during spring of 2009. The

J. C. Turnbull; A. Karion; M. L. Fischer; I. Faloona; T. Guilderson; S. J. Lehman; B. R. Miller; J. B. Miller; S. Montzka; T. Sherwood; S. Saripalli; C. Sweeney; P. P. Tans

2010-01-01

210

Measurement of fossil fuel derived carbon dioxide and other anthropogenic trace gases above Sacramento, California in Spring 2009  

Microsoft Academic Search

Direct quantification of fossil fuel CO2 (CO2ff) in atmospheric samples can be used to examine several carbon cycle and air quality questions. We collected in situ CO2, CO, and CH4 measurements and flask samples in the boundary layer and free troposphere over Sacramento, California, USA, during two aircraft flights over and downwind of this urban area during spring of 2009.

J. C. Turnbull; A. Karion; M. L. Fischer; I. C. Faloona; T. P. Guilderson; S. J. Lehman; B. R. Miller; J. B. Miller; S. A. Montzka; T. Sherwood; S. Saripalli; C. Sweeney; P. P. Tans

2010-01-01

211

Carbon isotopes of Middle–Lower Jurassic coal-derived alkane gases from the major basins of northwestern China  

Microsoft Academic Search

Coal-derived hydrocarbons from Middle–Lower Jurassic coal-bearing strata in northwestern China are distributed in the Tarim, Junggar, Qaidam, and Turpan-Harmi basins. The former three basins are dominated by coal-derived gas fields, distributed in Cretaceous and Tertiary strata. Turpan-Harmi basin is characterized by coal-derived oil fields which occur in the coal measures. Based on analysis of gas components and carbon isotopic compositions

Jinxing Dai; Caineng Zou; Jian Li; Yunyan Ni; Guoyi Hu; Xiaobao Zhang; Quanyou Liu; Chun Yang; Anping Hu

2009-01-01

212

Atmospheric Pollutants and Trace Gases Growth and Yield Responses of Potato to Mixtures of Carbon Dioxide and Ozone  

Microsoft Academic Search

enrichment is greater when O3 concentrations are also high (Barnes and Pfirrmann, 1992; Heagle et al., 1998; Elevated carbon dioxide (CO2) concentrations in the atmosphere Idso and Idso, 1994; Miller et al., 1998; Mulchi et al., can stimulate plant growth and yield, whereas ground-level ozone (O3) concentrations cause the opposite effect in many areas of the 1992). Apparently, CO2 can

A. S. Heagle; J. E. Miller; W. A. Pursley

213

Isotopic composition of gases from mud volcanoes  

SciTech Connect

A study has been made of the isotopic composition of the carbon in methane and carbon dioxide, as well as hydrogen in the methane, in the gases of mud volcanoes, for all main mud volcano areas in the USSR. The isotopic composition of carbon and hydrogen in methane shows that the gases resemble those of oil and gas deposits, while carbon dioxide of these volcanoes has a heavier isotopic composition with a greater presence of ''ultraheavy'' carbon dioxide. By the chemical and isotopic composition of gases, Azerbaidzhan and South Sakhalin types of mud volcano gases have been identified, as well as Bulganak subtypes and Akhtala and Kobystan varieties. Correlations are seen between the isotopic composition of gases and the geological build of mud volcano areas.

Valysaev, B.M.; Erokhin, V.E.; Grinchenko, Y.I.; Prokhorov, V.S.; Titkov, G.A.

1985-09-01

214

Fabrication of carbon-aerogel electrodes for use in phosphoric acid fuel cells  

E-print Network

An experiment was done to determine the ability to fabricate carbon aerogel electrodes for use in a phosphoric acid fuel cell (PAFC). It was found that the use of a 25% solution of the surfactant Cetyltrimethylammonium ...

Tharp, Ronald S

2005-01-01

215

Surfactant Screening to Alter the Wettability and Aid in Acidizing Carbonate Formations  

E-print Network

Surfactant flooding in carbonate matrix acidizing treatment has been widely used for changing the wettability of the rock and to achieve low IFT values. Optimizing the type of surfactant and concentration for the specific oil field is very important...

Yadhalli Shivaprasad, Arun Kumar

2013-02-26

216

Removal of Acid Dyes from Aqueous Solutions using Chemically Activated Carbon  

Microsoft Academic Search

Textile dyes (Acid Yellow 17 and Acid Orange 7) were removed from its aqueous solution in batch and continuous packed bed adsorption systems by using thermally activated Euphorbia macroclada carbon with respect to contact time, initial dye concentration, and temperature. The activated carbon was prepared using a cheap plant-based material called Euphorbia macroclada, which was chemically modified with K2CO3. Lagergren-first-order

Özgül Gerçel; H. Ferdi Gerçel

2009-01-01

217

A model for matrix acidizing of long horizontal well in carbonate reservoirs  

E-print Network

A MODEL FOR MATRIX ACIDIZING OF LONG HORIZONTAL WELL IN CARBONATE RESERVOIRS A Thesis by VARUN MISHRA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August 2007 Major Subject: Petroleum Engineering A MODEL FOR MATRIX ACIDIZING OF LONG HORIZONTAL WELL IN CARBONATE RESERVOIRS A Thesis by VARUN MISHRA Submitted to the Office...

Mishra, Varun

2009-06-02

218

Effective Condition for Purification of Multi-Walled Carbon Nanotubes by Nitric Acid  

Microsoft Academic Search

The multi-walled carbon nanotubes were synthesized on Fe-Ni bimetallic catalysts supported by MgO using thermal chemical vapor deposition. A comparative study on the effect of nitric acid molarity and time duration of acid treatment on purification of multi-walled nanotubes was done. The studies revealed that for finding a suitable condition for purification of multi-walled carbon nanotubes, it is necessary to

S. Mirershadi; S. Z. Mortazavi; A. Reyhani; N. Moniri; A. J. Novinrooz

2009-01-01

219

Effective Condition for Purification of Multi-walled Carbon Nanotubes by Nitric Acid  

Microsoft Academic Search

The multi-walled carbon nanotubes were synthesized on Fe-Ni bimetallic catalysts supported by MgO using thermal chemical vapor deposition. A comparative study on the effect of nitric acid molarity and time duration of acid treatment on purification of multi-walled nanotubes was done. The studies revealed that for finding a suitable condition for purification of multi-walled carbon nanotubes, it is necessary to

S. Mirershadi; S. Z. Mortazavi; A. Reyhani; N. Moniri; A. J. Novinrooz

2009-01-01

220

Properties of carbonized and converted uranium-loaded weak-acid resins  

Microsoft Academic Search

Weak-acid ion-exchange resins have been found to provide a practical method for fabricating uranium-containing HTGR fuel kernels. Two steps, thermal decomposition or carbonization and carbothermic reduction of UO or conversion, are required in the manufacture of these kernels. The property variations during carbonization of uranium-loaded weak-acid resin-derived fuel proceeds in a manner closely analogous to its thermogravimetric characteristics, particularly the

G. W. Weber; R. L. Beatty; V. J. Tennery

1977-01-01

221

The Effect of Heterogeneity on Matrix Acidizing of Carbonate Rocks  

E-print Network

In matrix acidizing, the goal is to dissolve minerals in the rock to increase well productivity. This is accomplished by injecting an application-specific solution of acid into the formation at a pressure between the pore pressure and fracture...

Keys, Ryan S.

2010-07-14

222

Greenhouse Gases  

NSDL National Science Digital Library

This is a lesson where learners engage in a radiating heat activity and an activity that measures temperature in models with and without greenhouse gases. Learners will draw conclusions about the effect of greenhouse gases on temperature and on human life and kinesthetically model the absorbing and re-radiation of heat. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes, prerequisite concepts, common misconceptions, student journal and reading. This is lesson 3 in the Astro-Venture Atmospheric Science Training Unit. The purpose of the unit is to increase studentsâ awareness of and interest in astrobiology and the many career opportunities that utilize science, math and technology skills. The lessons are designed for educators to use in conjunction with the Astro-Venture multimedia modules.

223

SIMULTANEOUS INHIBITION OF CARBON AND NITROGEN MINERALIZATION IN A FOREST SOIL BY SIMULATED ACID PRECIPITATION  

EPA Science Inventory

Acid Precipitation may alter the rates of microbial processes in soil that are important for forest productivity. Acidification of soil can result in a depression of carbon mineralization. The present study was designed to determine whether the inhibition of carbon mineralization...

224

USE OF THE COMPOSITION AND STABLE CARBONIISOTOPE RATIO OF MICROBIAL FATTY ACIDS TO STUDY CARBON CYCLING  

EPA Science Inventory

We use measurements of the concentration and stable carbon isotopic ratio (*13C) of individual microbial phospholipid fatty acids (PLFAs) in soils and sediments as indicators of live microbial biomass levels and microbial carbon source. For studies of soil organic matter (SOM) cy...

225

Formic acid oxidation at spontaneously deposited palladium on polyaniline modified carbon fibre paper  

Microsoft Academic Search

Extended reaction zone anodes for formic acid oxidation have been prepared by the spontaneous deposition of Pd on polyaniline coated carbon fibre paper. The PANI supports, deposited on carbon fibre paper either galvanostatically, potentiostatically, or potentiodynamically, were characterized by electron microscopy, cyclic voltammetry and impedance spectroscopy. Pd was deposited on them by spontaneous reduction of Pd(II) by the reduced form

Reza B. Moghaddam; Peter G. Pickup

2011-01-01

226

Production of activated carbon from a new precursor molasses by activation with sulphuric acid  

Microsoft Academic Search

Activated carbon has been prepared from molasses, a natural precursor of vegetable origin resulting from the sugar industry in Morocco. The preparation of the activated carbon from the molasses has been carried out by impregnation of the precursor with sulphuric acid, followed by carbonisation at varying conditions (temperature and gas coverage) in order to optimize preparation parameters. The influence of

K. Legrouri; E. Khouya; M. Ezzine; H. Hannache; R. Denoyel; R. Pallier; R. Naslain

2005-01-01

227

Effect of organic acids on the determination of carbonate species in solutions  

Microsoft Academic Search

Accurate analysis of carbonate species in natural waters is important for diagenetic modelling and oilfield inorganic chemical scale precipitation estimation. The concentration of carbonate species is often measured by titration. Errors can occur when organic acids are present in the solution due to the titration end points not being clearly identified. In this paper a method is presented for the

Yuping Zhang; Richard Dawe

1996-01-01

228

Noble Gases  

NASA Astrophysics Data System (ADS)

The noble gases are the group of elements - helium, neon, argon, krypton, xenon - in the rightmost column of the periodic table of the elements, those which have "filled" outermost shells of electrons (two for helium, eight for the others). This configuration of electrons results in a neutral atom that has relatively low electron affinity and relatively high ionization energy. In consequence, in most natural circumstances these elements do not form chemical compounds, whence they are called "noble." Similarly, much more so than other elements in most circumstances, they partition strongly into a gas phase (as monatomic gas), so that they are called the "noble gases" (also, "inert gases"). (It should be noted, of course, that there is a sixth noble gas, radon, but all isotopes of radon are radioactive, with maximum half-life a few days, so that radon occurs in nature only because of recent production in the U-Th decay chains. The factors that govern the distribution of radon isotopes are thus quite different from those for the five gases cited. There are interesting stories about radon, but they are very different from those about the first five noble gases, and are thus outside the scope of this chapter.)In the nuclear fires in which the elements are forged, the creation and destruction of a given nuclear species depends on its nuclear properties, not on whether it will have a filled outermost shell when things cool off and nuclei begin to gather electrons. The numerology of nuclear physics is different from that of chemistry, so that in the cosmos at large there is nothing systematically special about the abundances of the noble gases as compared to other elements. We live in a very nonrepresentative part of the cosmos, however. As is discussed elsewhere in this volume, the outstanding generalization about the geo-/cosmochemistry of the terrestrial planets is that at some point thermodynamic conditions dictated phase separation of solids from gases, and that the Earth and the rest of the inner solar were made by collecting the solids, to the rather efficient exclusion of the gases. In this grand separation the noble gases, because they are noble, were partitioned strongly into the gas phase. The resultant generalization is that the noble gases are very scarce in the materials of the inner solar system, whence their common synonym "rare gases."This scarcity is probably the most important single feature to remember about noble-gas cosmochemistry. As illustration of the absolute quantities, for example, a meteorite that contains xenon at a concentration of order 10 -10 cm3STP g -1 (4×10-15 mol g-1) would be considered relatively rich in xenon. Yet this is only 0.6 ppt (part per trillion, fractional abundance 10-12) by mass. In most circumstances, an element would be considered efficiently excluded from some sample if its abundance, relative to cosmic proportions to some convenient reference element, were depleted by "several" orders of magnitude. But a noble gas would be considered to be present in quite high concentration if it were depleted by only four or five orders of magnitude (in the example above, 10-10 cm3STP g-1 of xenon corresponds to depletion by seven orders of magnitude), and one not uncommonly encounters noble-gas depletion of more than 10 orders of magnitude.The second most important feature to note about noble-gas cosmochemistry is that while a good deal of the attention given to noble gases really is about chemistry, traditionally a good deal of attention is also devoted to nuclear phenomena, much more so than for most other elements. This feature is a corollary of the first feature noted above, namely scarcity. A variety of nuclear transmutation processes - decay of natural radionuclides and energetic particle reactions - lead to the production of new nuclei that are often new elements. Most commonly, the quantity of new nuclei originating in nuclear transmutation is very small compared to the quantity already present in the sample in question,

Podosek, F. A.

2003-12-01

229

Preparation of a novel carbon-based solid acid from cassava stillage residue and its use for the esterification of free fatty acids in waste cooking oil.  

PubMed

A novel carbon-based solid acid catalyst was prepared by the sulfonation of incompletely carbonized cassava stillage residue (CSR) with concentrated sulfuric acid, and employed to catalyze the esterification of methanol and free fatty acids (FFAs) in waste cooking oil (WCO). The effects of the carbonization and the sulfonation temperatures on the pore structure, acid density and catalytic activity of the CSR-derived catalysts were systematically investigated. Low temperature carbonization and high temperature sulfonation can cause the collapse of the carbon framework, while high temperature carbonization is not conducive to the attachment of SO3H groups on the surface. The catalyst showed high catalytic activity for esterification, and the acid value for WCO is reduced to below 2mg KOH/g after reaction. The activity of catalyst can be well maintained after five cycles. CSR can be considered a promising raw material for the production of a new eco-friendly solid acid catalyst. PMID:24661813

Wang, Lingtao; Dong, Xiuqin; Jiang, Haoxi; Li, Guiming; Zhang, Minhua

2014-04-01

230

Oxidation and reduction rates for organic carbon in the Amazon mainstream tributary and floodplain, inferred from distributions of dissolved gases  

NASA Technical Reports Server (NTRS)

Concentrations of CO2, O2, CH4, and N2O in the Amazon River system reflect an oxidation-reduction sequence in combination with physical mixing between the floodplain and the mainstem. Concentrations of CO2 ranged from 150 microM in the Amazon mainstem to 200 to 300 microM in aerobic waters of the floodplain, and up to 1000 microM in oxygen-depleted environments. Apparent oxygen utilization (AOU) ranged from 80 to 250 microM. Methane was highly supersaturated, with concentrations ranging from 0.06 microM in the mainstem to 100 microM on the floodplain. Concentrations of N2O were slightly supersaturated in the mainstem, but were undersaturated on the floodplain. Fluxes calculated from these concentrations indicated decomposition of 1600 g C sq m y(-1) of organic carbon in Amazon floodplain waters. Analysis of relationships between CH4, O2, and CO2 concentrations indicated that approximately 50 percent of carbon mineralization on the floodplain is anaerobic, with 20 percent lost to the atmoshphere as CH4. The predominance of anaerobic metabolism leads to consumption of N2O on the flood plane. Elevated concentrations of CH4 in the mainstem probably reflect imput from the floodplain, while high levels of CO2 in the mainstem are derived from a combination of varzea drainage and in situ respiration.

Richey, Jeffrey E.; Devol, Allan H.; Wofsy, Steven C.; Victoria, Reynaldo; Riberio, Maria N. G.

1986-01-01

231

Arterial blood gases and acid-base status of adult patients presenting with acute severe asthma at Kenyatta National Hospital, Nairobi.  

PubMed

Forty adult patients with acute severe asthma were assessed for arterial blood gases and acid-base changes at presentation at the Casualty Unit, Kenyatta National Hospital, Nairobi, Kenya. Marked degrees of hypoxaemia (mean P(a)O2 of 8.02 kP(a)), hypocapnia (mean P(a)CO2 of 4.62kP(a)) with apparently normal pH (mean 7.384) were documented in the majority of these patients. Based on these findings, a significant number of the patients (68.5%) were either candidates (5.3%) or potential candidates (63.2%) for artificial ventilation. Records at this hospital suggest an increasing trend in asthma admissions and mortality. Additionally, Intensive Care Unit (ICU) admissions for asthma are associated with high mortality (54.4%). Pulsus paradoxicus emerged as the most significant (p = 0.002) clinical correlate to asthma severity. Central cyanosis was detected in none of the study patients suggesting that it is an unusual finding in the common presentation of acute severe asthma at this hospital. Its clinical detection would therefore imply an ominous clinical state. It is recommended that clinicians should take every opportunity to adequately assess their asthma patients before prescribing medications. They are also encouraged to more frequently request for blood gas studies in acute asthma. Those in charge of clinical teaching should direct appropriate efforts towards improved understanding of the pathophysiology and interpretation of acid-base disorders. PMID:1505418

Odhiambo, J A; Chwala, R D

1992-06-01

232

Bias-dependent amino-acid-induced conductance changes in short semi-metallic carbon nanotubes  

E-print Network

Bias-dependent amino-acid-induced conductance changes in short semi-metallic carbon nanotubes G-acid adsorption are bias-dependent. PACS number: 72.80.RJ Submitted to: Nanotechnology #12;Bias that is confirmed by calculations for armchair tubes that are not presented in this paper), or semiconducting tubes

Pulfrey, David L.

233

Sulfate Reducing Rate of SRB with Acetic, Propionic, n-Butyric Acids as Carbon Sources  

Microsoft Academic Search

The aim of this work was to determine the kind of short-chain volatile fatty acid, which is apt to be used by sulfate reducing bacteria (SRB). SRB was feed with culture media used sodium lactate as carbon source. Sulfate reducing rate and different short-chain volatile fatty acids (VFA) utilization rate with SRB were studied. Sulfate variation curves were drawn and

Xiulan Song; Zhimin Zhang

2011-01-01

234

Seasonal variations of water-soluble organic carbon, dicarboxylic acids, ketocarboxylic acids, and ?-dicarbonyls in Central Himalayan aerosols  

NASA Astrophysics Data System (ADS)

Aerosol samples were collected from a high elevation mountain site (Nainital, India; 1958 m a.s.l.) in the central Himalayas, a location that provides an isolated platform above the planetary boundary layer to better understand the composition of the remote continental troposphere. The samples were analyzed for water-soluble dicarboxylic acids (C2-C12) and related compounds (ketocarboxylic acids and ?-dicarbonyls), as well as organic carbon, elemental carbon and water soluble organic carbon. The contributions of total dicarboxylic acids to total aerosol carbon during wintertime were 1.7% and 1.8%, for day and night, respectively whereas they were significantly smaller during summer. Molecular distributions of diacids revealed that oxalic (C2) acid was the most abundant species followed by succinic (C4) and malonic (C3) acids. The average concentrations of total diacids (433±108 ng m-3), ketoacids (48±23 ng m-3), and ?-dicarbonyls (9±4 ng m-3) were similar to those from large Asian cities such as Tokyo, Beijing and Hong Kong. During summer most of the organic species were several times more abundant than in winter. Phthalic acid, which originates from oxidation of polycyclic aromatic hydrocarbons such as naphthalene, was found to be 7 times higher in summer than winter. This feature has not been reported before in atmospheric aerosols. Based on molecular distributions and air mass backward trajectories, we conclude that dicarboxylic acids and related compounds in Himalayan aerosols are derived from anthropogenic activities in the highly populated Indo-Gangetic plain areas.

Hegde, P.; Kawamura, K.

2012-07-01

235

Adsorption of aromatic organic acids onto high area activated carbon cloth in relation to wastewater purification  

Microsoft Academic Search

Adsorption of aromatic organic acids: benzoic acid (BA), salicylic acid (SA), p-aminobenzoic acid (pABA) and nicotinic acid (NA), onto high area activated carbon cloth from solutions in 0.4M H2SO4, in water at natural pH, in 0.1M NaOH and also from solutions having pH 7.0 were studied by in situ UV-spectroscopic technique. The first-order rate law was found to be applicable

Erol Ayranci; Osman Duman

2006-01-01

236

Effect of carbon chain length on esterification of carboxylic acids with methanol using acid catalysis  

Microsoft Academic Search

This paper reports on an investigation into the impact of carboxylic acid chain length on the kinetics of liquid-phase acid-catalyzed esterification. Using sulfuric acid and a commercial Nafion\\/silica composite solid acid catalyst (SAC-13), initial kinetics were measured for the reactions of a series of linear chain carboxylic acids (acetic, propionic, butyric, hexanoic, and caprylic acid) with methanol at 60?°C. It

Yijun Liu; Edgar Lotero; James G. Goodwin

2006-01-01

237

Influence of carbons on the structure of the negative active material of lead-acid batteries and on battery performance  

Microsoft Academic Search

It has been established that addition of carbon additives to the lead negative active material (NAM) of lead-acid batteries increase battery charge acceptance in hybrid electric vehicle mode of operation. The present work studies three types of activated carbons and two types of carbon blacks with the aim to evaluate their efficiency in improving the charge acceptance of lead-acid batteries.

D. Pavlov; P. Nikolov; T. Rogachev

2011-01-01

238

Stable carbon isotope ratios of fatty acids in seagrass and redhead ducks  

Microsoft Academic Search

Fatty acids were extracted from roots and rhizomes of the seagrass, Halodule wrightii, and from subcutaneous fat tissues of eight redhead ducks (Aythya americana) collected either in Texas or South Dakota. Stable carbon isotope ratios (?13C) of individual fatty acids were measured by gas chromatography\\/combustion\\/isotope ratio mass spectrometry (GC\\/C\\/IRMS). In cases where individual fatty acids were not completely resolved by

Beth Trust Hammer; Marilyn L. Fogel; Thomas C. Hoering

1998-01-01

239

Arachidonic and Docosahexaenoic Acids are Biosynthesized from their 18Carbon Precursors in Human Infants  

Microsoft Academic Search

It is becoming clear that an adequate level of long-chain highly unsaturated fatty acids in the nervous system is required for optimal function and development; however, the ability of infants to biosynthesize long-chain fatty acids is unknown. This study explores the capacity of human infants to convert 18-carbon essential fatty acids to their elongated and desaturated forms, in vivo. A

Norman Salem; Brent Wegher; Patricia Mena; Ricardo Uauy

1996-01-01

240

Electrochemical behavior of negative electrode of lead-acid cells based on reticulated vitreous carbon carrier  

Microsoft Academic Search

Reticulated vitreous carbon (RVC®) and RVC® plated with lead were investigated as carriers for the negative electrode of lead-acid cell. The RVC® and Pb\\/RVC® carriers were pasted with active paste (received from JENOX Ltd., Polish producer of lead-acid batteries) and prepared to be used in lead-acid cell. Comparative study of electrodes based on RVC® and Pb\\/RVC® has been done using

A. Czerwi?ski; S. Obr?bowski; J. Kotowski; Z. Rogulski; J. M. Skowro?ski; P. Krawczyk; T. Rozmanowski; M. Bajsert; M. Przysta?owski; M. Buczkowska-Biniecka; E. Jankowska; M. Baraniak

2010-01-01

241

Use of molecular modeling to determine the interaction and competition of gases within coal for carbon dioxide sequestration  

SciTech Connect

Molecular modeling was employed to both visualize and probe our understanding of carbon dioxide sequestration within a bituminous coal. A large-scale (>20,000 atoms) 3D molecular representation of Pocahontas No. 3 coal was generated. This model was constructed based on a the review data of Stock and Muntean, oxidation and decarboxylation data for aromatic clustersize frequency of Stock and Obeng, and the combination of Laser Desorption Mass Spectrometry data with HRTEM, enabled the inclusion of a molecular weight distribution. The model contains 21,931 atoms, with a molecular mass of 174,873 amu, and an average molecular weight of 714 amu, with 201 structural components. The structure was evaluated based on several characteristics to ensure a reasonable constitution (chemical and physical representation). The helium density of Pocahontas No. 3 coal is 1.34 g/cm{sup 3} (dmmf) and the model was 1.27 g/cm{sup 3}. The structure is microporous, with a pore volume comprising 34% of the volume as expected for a coal of this rank. The representation was used to visualize CO{sub 2}, and CH{sub 4} capacity, and the role of moisture in swelling and CO{sub 2}, and CH{sub 4} capacity reduction. Inclusion of 0.68% moisture by mass (ash-free) enabled the model to swell by 1.2% (volume). Inclusion of CO{sub 2} enabled volumetric swelling of 4%.

Jeffrey D. Evanseck; Jeffry D. Madura; Jonathan P. Mathews

2006-04-21

242

Stimulation of Carbonate Reservoirs Using a New Emulsified Acid System  

E-print Network

The scope of work can be divided into; the measurement of the rheological properties of a new emulsified acid system that can be suitable for high temperature applications, a study of the performance of the new emulsified acid in stimulating both...

Sayed, Mohammed Ali Ibrahim

2013-05-15

243

USE OF MOLECULAR MODELING TO DETERMINE THE INTERACTION AND COMPETITION OF GASES WITHIN COAL FOR CARBON DIOXIDE SEQUESTRATION  

SciTech Connect

We have made progress in carrying out large scale molecular dynamics simulations using the CHARMM force field in order to refine our coal/guest interactions. There have been two issues facing us over the last year. First, we have had to create a completely new topology and parameter definition for coal. Since we are using a classical force field, we have adopted the strategy of treating coal composed of individual common fragments based upon a distribution of mass, composition, and bonding. Our procedure is similar to treating a protein as being composed of the discrete set of amino acids. Second, we have had to incorporate the quality CO{sub 2} parameters that we have developed over the last two years. There are the geometric and arithmetic procedures, which we have successfully implemented. We have utilized computational molecular modeling to generate a state-of-the-art large scale structural representation of a bituminous coal of low volatile bituminous rank. This structure(s) has been used to investigate the molecular forces between the bituminous coal structure (or idealized pores) and the molecular species CH{sub 4} and CO{sub 2}. We are close to carrying out molecular dynamics simulations, which will allow us to explore and test the newly created model of coal.

Jeffrey D. Evanseck; Jeffry D. Madura; Jonathan P. Mathews

2005-05-27

244

Acid-activated carbons from almond shells: physical, chemical and adsorptive properties and estimated cost of production  

Microsoft Academic Search

A series of phosphoric-acid activated carbons were made from almond shells using six different activation or activation\\/oxidation methods. The carbons were compared to each other and to two commercial carbons in an effort to ascertain the relative value of the carbons in terms of yield, surface area, attrition, surface functional groups, organic uptake, metal uptake, as well as estimated cost

Christopher A Toles; Wayne E Marshall; Mitchell M Johns; Lynda H Wartelle; Andrew McAloon

2000-01-01

245

Production and characterization of methyl ester sophorolipids with 22-carbon-fatty acids.  

PubMed

In this study, various fatty acids of 18 and 22 carbons were used as substrates to produce sophorolipids in Candida bombicola ATCC 22214. Methyl esterification of erucic acid and C22-enriched rapeseed oil generated mainly acidic sophorolipids with different degrees of saturation in the fatty acid chain, which was demonstrated by structural analysis using HPLC, LC-MS and NMR spectroscopy. Regardless of methyl esterification, the rapeseed oil served as the best substrate for high production of sophorolipids among the tested. Methyl esterification also had no noticeable effect on the interfacial properties of sophorolipids. However, 22 carbons introduced in the fatty acid chain increased the hydrophobicity of sophorolipids, and therefore improved surface-active properties and biodegradability. PMID:20053555

Shin, Jae Dong; Lee, Jeongmi; Kim, Yong Bum; Han, In-Sun; Kim, Eun-Ki

2010-05-01

246

Carbon doping of MgB 2 by toluene and malic-acid-in-toluene  

NASA Astrophysics Data System (ADS)

The decomposition of malic acid (C 4H 6O 5) in the presence of Mg and B was studied using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) which revealed that malic acid reacted with Mg but not B. Also, the addition of toluene (C 7H 8) to dissolve malic acid followed by subsequent drying resulted in no reaction with Mg, indicating that the malic acid had decomposed during the dissolution/drying stage. The total carbon contributed by toluene versus a toluene/5 wt.% malic acid mixture was measured using a LECO CS600 carbon analyzer. The toluene sample contained ?0.4 wt.% C while the toluene/malic acid mixture had ?1.5 wt.% C, demonstrating that the toluene contributed a significant amount of carbon to the final product. Resistivity measurements on powder-in-tube MgB 2 monofilamentary wires established that the toluene/malic acid doped sample had the highest B c2. However, the toluene-only sample had the highest transport J c over most of the magnetic field range (0-9 T), equaled only by that of toluene/malic-acid sample in fields above 9 T.

Bohnenstiehl, S. D.; Susner, M. A.; Yang, Y.; Collings, E. W.; Sumption, M. D.; Rindfleisch, M. A.; Boone, R.

2011-02-01

247

Influence of acid functionalization on the cardiopulmonary toxicity of carbon nanotubes and carbon black particles in mice  

SciTech Connect

Engineered carbon nanotubes are being developed for a wide range of industrial and medical applications. Because of their unique properties, nanotubes can impose potentially toxic effects, particularly if they have been modified to express functionally reactive chemical groups on their surface. The present study was designed to evaluate whether acid functionalization (AF) enhanced the cardiopulmonary toxicity of single-walled carbon nanotubes (SWCNT) as well as control carbon black particles. Mice were exposed by oropharyngeal aspiration to 10 or 40 {mu}g of saline-suspended single-walled carbon nanotubes (SWCNTs), acid-functionalized SWCNTs (AF-SWCNTs), ultrafine carbon black (UFCB), AF-UFCB, or 2 {mu}g LPS. 24 hours later, pulmonary inflammatory responses and cardiac effects were assessed by bronchoalveolar lavage and isolated cardiac perfusion respectively, and compared to saline or LPS-instilled animals. Additional mice were assessed for histological changes in lung and heart. Instillation of 40 {mu}g of AF-SWCNTs, UFCB and AF-UFCB increased percentage of pulmonary neutrophils. No significant effects were observed at the lower particle concentration. Sporadic clumps of particles from each treatment group were observed in the small airways and interstitial areas of the lungs according to particle dose. Patches of cellular infiltration and edema in both the small airways and in the interstitium were also observed in the high dose group. Isolated perfused hearts from mice exposed to 40 {mu}g of AF-SWCNTs had significantly lower cardiac functional recovery, greater infarct size, and higher coronary flow rate than other particle-exposed animals and controls, and also exhibited signs of focal cardiac myofiber degeneration. No particles were detected in heart tissue under light microscopy. This study indicates that while acid functionalization increases the pulmonary toxicity of both UFCB and SWCNTs, this treatment caused cardiac effects only with the AF-carbon nanotubes. Further experiments are needed to understand the physico-chemical processes involved in this phenomenon.

Tong Haiyan [Human Studies Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711 (United States)], E-mail: tong.haiyan@epa.gov; McGee, John K. [Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711 (United States); Saxena, Rajiv K. [School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Kodavanti, Urmila P. [Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711 (United States); Devlin, Robert B. [Human Studies Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711 (United States); Gilmour, M. Ian [Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711 (United States)

2009-09-15

248

Carbon dioxide-sustained adsorption of lactic acid at pH > pK{sub a} of the acid  

SciTech Connect

Experimental data are presented for batch and fixed-bed adsorption of lactic acid from aqueous sodium lactate solutions onto the tertiary amine sorbents, Dowex MWA-1 and Amberlite IRA-35, in the presence of carbon dioxide. The effects of carbon dioxide pressure and sodium lactate concentration on lactate uptake capacity were measured. A simple complexation model, which includes chemical-equilibria and mass- and charge-balance equations, was developed to describe the system. There are no fitted parameters in the model. The model predictions compare well with batch adsorption data.

Husson, S.M.; King, C.J. [Lawrence Berkeley National Lab., CA (United States)] [Lawrence Berkeley National Lab., CA (United States)

1999-04-01

249

Synthesis of biodiesel from waste vegetable oil with large amounts of free fatty acids using a carbon-based solid acid catalyst  

Microsoft Academic Search

A carbon-based solid acid catalyst was prepared by the sulfonation of carbonized vegetable oil asphalt. This catalyst was employed to simultaneously catalyze esterification and transesterification to synthesis biodiesel when a waste vegetable oil with large amounts of free fatty acids (FFAs) was used as feedstock. The physical and chemical properties of this catalyst were characterized by a variety of techniques.

Qing Shu; Jixian Gao; Zeeshan Nawaz; Yuhui Liao; Dezheng Wang; Jinfu Wang

2010-01-01

250

Greenhouse Gases  

MedlinePLUS

... global population has increased and our reliance on fossil fuels (such as coal, oil and natural gas) has ... agricultural sources for the gas, some industrial processes (fossil fuel-fired power plants, nylon production, nitric acid production ...

251

Use of Pyrolyzed Iron Ethylenediaminetetraacetic Acid Modified Activated Carbon as Air-Cathode Catalyst in Microbial Fuel Cells  

E-print Network

Use of Pyrolyzed Iron Ethylenediaminetetraacetic Acid Modified Activated Carbon as Air activity of AC cathodes, AC powders were pyrolyzed with iron ethylenediaminetetraacetic acid (Fe MFCs was 50% lower than MFCs with the AC cathodes. Pyridinic nitrogen, quaternary nitrogen and iron

252

Pressure-Activated Microsyringe Composite Scaffold of Poly(L-lactic acid) and Carbon Nanotubes for Bone Tissue Engineering  

E-print Network

Pressure-Activated Microsyringe Composite Scaffold of Poly(L-lactic acid) and Carbon Nanotubes biocompatibility. In this study, we microfabricated three-dimensional (3D) scaffolds by mixing poly(L-lactic acid

Daraio, Chiara

253

Degradation and removal of naphthalenesulphonic acids by means of adsorption and ozonation catalyzed by activated carbon in water  

NASA Astrophysics Data System (ADS)

Studies were conducted on the efficiency of systems based on the use of ozone, activated carbon, and ozone/activated carbon in the treatment of waters containing 1-naphthalenesulphonic acid, 1,5-naphthalenedisulphonic acid, and 1,3,6-naphthalenetrisulphonic acid. In the removal of these acids by adsorption on activated carbon the elevated heights of the mass transfer zone columns and the low values of the breakthrough volumes indicated that a system exclusively based on the use of activated carbon is not appropriate for the removal of these pollutants. In the ozonation of these acids the reactivity of naphthalenesulphonic acid with ozone is low. In addition, the initial concentration of total organic carbon (TOC) was not reduced during naphthalenesulphonic acids ozonation. These results indicate that a system exclusively based on the use of ozone is not adequate to decontaminate water where these acids are present. These ozonation processes were also studied in the presence of activated carbon. The presence of activated carbon enhanced the elimination rate, probably by enhancing ozone decomposition in aqueous phase in highly oxidative species. These catalytic properties seem to be favored by both the basicity of the carbon surface and the higher macropore volume. The catalytic properties of activated carbon were reduced by ozonation. New acid groups such as anhydride, lactones, and carboxylic acid were generated on the activated carbon surface during ozone treatment. This effect reduced the reactivity of the activated carbon to ozone and therefore the capacity to enhance ozone decomposition in aqueous phase. The presence of activated carbon during naphthalenesulphonic acid ozonation produced a reduction in the TOC concentration and in the genotoxicity of the degradation products. All these results indicate that this novel combined system is very promising for the treatment of water polluted with organic matter.

Rivera-Utrilla, J.; SáNchez-Polo, M.

2003-09-01

254

Greenhouse Gases  

NSDL National Science Digital Library

Explore how the Earth's atmosphere affects the energy balance between incoming and outgoing radiation. Using an interactive model, adjust realistic parameters such as how many clouds are present or how much carbon dioxide is in the air, and watch how these factors affect the global temperature.

Consortium, The C.

2011-12-13

255

Covalent functionalization of single walled carbon nanotubes with peptide nucleic acid: Nanocomponents for molecular level electronics  

Microsoft Academic Search

Imparting molecular recognition to carbon nanotubes (CNTs) by conjugating them with bio-molecules has been an area of great interest as the resulting highly functionalized CNT-bioconjugates find their applications in various fields like molecular level electronics, pharmaceuticals, drug delivery, novel materials and many others. In this work we demonstrate the synthesis of functionally engineered single walled carbon nanotubes (SWNTs)-peptide nucleic acid

Krishna V. Singh; Rajeev R. Pandey; Xu Wang; Roger Lake; Cengiz S. Ozkan; Kang Wang; Mihrimah Ozkan

2006-01-01

256

Stable carbon isotope measurements of atmospheric organic acids in Los Angeles, California  

SciTech Connect

Atmospheric organic acids are ubiquitous constituents of urban smog and haze and are also present in the atmospheres of rural and largely uninhabited areas (e.g., the Amazon Rain Forest Basin). The authors report here source characterization of atmospheric organic acids in Los Angeles by measurements of their stable carbon isotopic ratios, e.g., {sup 13}C/{sup 12}C({delta}{sup 13}C). The study was performed by separating formic and acetic acids using ion chromatography exclusion (ICE) and isolating milligram quantities of individual organic acids from atmospheric rain samples. Authentic reference samples of formic and acetic acids were used to determine that only a negligible isotope fractionation of {delta}{sup 13}C value occurs after the ICE separation. During 1991-1992, rainwaters were collected in Los Angeles to isolate formic and acetic acids for the isotope measurements. Results presented in this paper demonstrate a significant isotopic difference between the mean {delta}{sup 13}C value for acetic acid ({minus}20.5{per_thousand}) and formic acid ({minus}30.1{per_thousand}). The authors conclude from these results that the formic acid is derived from mixing of formic acid from direct emissions with the acid formed by secondary oxidation processes in the atmosphere, most probably from aldehydes, whereas acetic acid originates only from direct source emissions. 26 refs., 1 fig., 2 tabs.

Sakugawa, H. [Hiroshima Univ. (Japan)] [Hiroshima Univ. (Japan); Kaplan, I.R. [Univ. of California, Los Angeles, CA (United States)] [Univ. of California, Los Angeles, CA (United States)

1995-06-15

257

Carbon isotope and abundance systematics of Icelandic geothermal gases, fluids and subglacial basalts with implications for mantle plume-related CO2 fluxes  

NASA Astrophysics Data System (ADS)

We report new carbon dioxide (CO2) abundance and isotope data for 71 geothermal gases and fluids from both high-temperature (HT > 150 °C at 1 km depth) and low-temperature (LT < 150 °C at 1 km depth) geothermal systems located within neovolcanic zones and older segments of the Icelandic crust, respectively. These data are supplemented by CO2 data obtained by stepped heating of 47 subglacial basaltic glasses collected from the neovolcanic zones. The sample suite has been characterized previously for He-Ne (geothermal) and He-Ne-Ar (basalt) systematics (Füri et al., 2010), allowing elemental ratios to be calculated for individual samples. Geothermal fluids are characterized by a wide range in carbon isotope ratios (?13C), from -18.8‰ to +4.6‰ (vs. VPDB), and CO2/3He values that span eight orders of magnitude, from 1 × 104 to 2 × 1012. Extreme geothermal values suggest that original source compositions have been extensively modified by hydrothermal processes such as degassing and/or calcite precipitation. Basaltic glasses are also characterized by a wide range in ?13C values, from -27.2‰ to -3.6‰, whereas CO2/3He values span a narrower range, from 1 × 108 to 1 × 1012. The combination of both low ?13C values and low CO2 contents in basalts indicates that magmas are extensively and variably degassed. Using an equilibrium degassing model, we estimate that pre-eruptive basaltic melts beneath Iceland contain ?531 ± 64 ppm CO2 with ?13C values of -2.5 ± 1.1‰, in good agreement with estimates from olivine-hosted melt inclusions (Metrich et al., 1991) and depleted MORB mantle (DMM) CO2 source estimates (Marty, 2012). In addition, pre-eruptive CO2 compositions are estimated for individual segments of the Icelandic axial rift zones, and show a marked decrease from north to south (Northern Rift Zone = 550 ± 66 ppm; Eastern Rift Zone = 371 ± 45 ppm; Western Rift Zone = 206 ± 24 ppm). Notably, these results are model dependent, and selection of a lower ?13C fractionation factor will result in lower source estimates and larger uncertainties associated with the initial ?13C estimate. Degassing can adequately explain low CO2 contents in basalts; however, degassing alone is unlikely to generate the entire spectrum of observed ?13C variations, and we suggest that melt-crust interaction, involving a low ?13C component, may also contribute to observed signatures. Using representative samples, the CO2 flux from Iceland is estimated using three independent methods: (1) combining measured CO2/3He values (in gases and basalts) with 3He flux estimates (Hilton et al., 1990), (2) merging basaltic emplacement rates of Iceland with pre-eruptive magma source estimates of ?531 ± 64 ppm CO2, and (3) combining fluid CO2 contents with estimated regional fluid discharge rates. These methods yield CO2 flux estimates from of 0.2-23 × 1010 mol a-1, which represent ?0.1-10% of the estimated global ridge flux (2.2 × 1012 mol a-1; Marty and Tolstikhin, 1998).

Barry, P. H.; Hilton, D. R.; Füri, E.; Halldórsson, S. A.; Grönvold, K.

2014-06-01

258

Recovery of calcium carbonate from steelmaking slag and utilization for acid mine drainage pre-treatment.  

PubMed

The conversion of steelmaking slag (a waste product of the steelmaking process) to calcium carbonate (CaCO(3)) was tested using hydrochloric acid, ammonium hydroxide and carbon dioxide via a pH-swing process. Batch reactors were used to assess the technical feasibility of calcium carbonate recovery and its use for pre-treatment of acid mine drainage (AMD) from coal mines. The effects of key process parameters, such as the amount of acid (HCl/calcium molar ratio), the pH and the CO(2) flow rate were considered. It was observed that calcium extraction from steelmaking slag significantly increased with an increase in the amount of hydrochloric acid. The CO(2) flow rate also had a positive effect on the carbonation reaction rate but did not affect the morphology of the calcium carbonate produced for values less than 2 L/min. The CaCO(3) recovered from the bench scale batch reactor demonstrated effective neutralization ability during AMD pre-treatment compared with the commercial laboratory grade CaCO(3). PMID:22643421

Mulopo, J; Mashego, M; Zvimba, J N

2012-01-01

259

Revised black carbon assessment using benzene polycarboxylic acids  

Microsoft Academic Search

Black carbon (BC), the ubiquitous stable product of incomplete combustion, is believed to be a potential sink for atmospheric CO2 and therefore a contributor to the Earth’s radiative heat balance. Nevertheless, analytical procedures to measure BC are inconsistent, giving a non-systematic variation by factors of 14–571 for estimates of its content in soil. We hypothesized that the HCl used to

S. Brodowski; A. Rodionov; L. Haumaier; B. Glaser; W. Amelung

2005-01-01

260

A microalgae residue based carbon solid acid catalyst for biodiesel production.  

PubMed

Biodiesel production from microalgae is recognized as one of the best solutions to deal with the energy crisis issues. However, after the oil extraction from the microalgae, the microalgae residue was generally discarded or burned. Here a novel carbon-based solid acid catalyst derived from microalgae residue by in situ hydrothermal partially carbonization were synthesized. The obtained catalyst was characterized and subjected to both the esterification of oleic acid and transesterification of triglyceride to produce biodiesel. The catalyst showed high catalytic activity and can be regenerated while its activity can be well maintained after five cycles. PMID:23953130

Fu, Xiaobo; Li, Dianhong; Chen, Jie; Zhang, Yuanming; Huang, Weiya; Zhu, Yi; Yang, Jun; Zhang, Chengwu

2013-10-01

261

Multi-walled carbon nanotubes in aqueous phytic acid for enhancing biosensor  

NASA Astrophysics Data System (ADS)

The poor dispersion of carbon based nanomaterials without strong acid pretreatment in aqueous solution is a fundamental problem, limiting its applications in biology-related fields. A good dispersion of multi-walled carbon nanotubes (MWCNTs) in water was realized by 50 wt.% phytic acid (PA) solution. As an application case, the PA-MWCNTs dispersion in aqueous solution was used for the immobilization of horseradish peroxidase (HRP) and its direct electrochemistry was realized. The constructed biosensor has a sound limit of detection, wide linear range, and high affinity for hydrogen peroxide (H2O2) as well as being free from interference of co-existing electro-active species.

Guo, Xiaoyu; Miao, Yun; Ye, Pingping; Wen, Ying; Yang, Haifeng

2014-04-01

262

The electrochemical reduction of carbon dioxide to formate/formic acid: engineering and economic feasibility.  

PubMed

The engineering and economic feasibility of large-scale electrochemical reduction of carbon dioxide to formate salts and formic acid is the focus of this Full Paper. In our study we investigated the long-term performance of tin and other proprietary catalysts in the reduction of carbon dioxide to formate/formic acid at a gas/solid/liquid interface, using a flow-through reactor. The overall economics and energy consumption of the process are evaluated through a value chain analysis. The sensitivity of the net present value of the process to various process parameters is examined. PMID:21922681

Agarwal, Arun S; Zhai, Yumei; Hill, Davion; Sridhar, Narasi

2011-09-19

263

Acetaldehyde stimulation of net gluconeogenic carbon movement from applied malic acid in tomato fruit pericarp tissue  

SciTech Connect

Applied acetaldehyde is known to lead to sugar accumulation in fruit including tomatoes (Lycopersicon esculentum) presumably due to stimulation of gluconeogenesis. This conjecture was examined using tomato fruit pericarp discs as a test system and applied l-(U-{sup 14}C)malic acid as the source for gluconeogenic carbon mobilization. Results indicate that malic and perhaps other organic acids are carbon sources for gluconeogenesis occurring normally in ripening tomatoes. The process is stimulated by acetaldehyde apparently by attenuating the fructose-2,6-biphosphate levels. The mode of the acetaldehyde regulation of fructose-2,6-biphosphate metabolism awaits clarification.

Halinska, A.; Frenkel, C. (Rutgers, The State Univ. of New Jersey, New Brunswick (United States))

1991-03-01

264

Carbon dioxide curing of plates for lead--acid batteries  

Microsoft Academic Search

A process for curing lead--acid battery plates by exposing them to COâ in the presence of water is described. Since the cohesion of the active material is improved, a more open grid structure may be employed. The process is of value for both cathodes and anodes. (RWR)

Yarnell

1975-01-01

265

Toxicity of pyrolysis gases from polyoxymethylene  

NASA Technical Reports Server (NTRS)

A sample of polyoxymethylene was evaluated for toxicity of pyrolysis gases, using the toxicity screening test method developed at the University of San Francisco. Under several test conditions, this material gave shorter times to death than many other synthetic polymers. Carbon monoxide appeared to be the principal toxicant in the pyrolysis gases.

Hilado, C. J.; Schneider, J. E.; Brauer, D. P.

1979-01-01

266

Quantification and mass isotopomer profiling of ?-keto acids in central carbon metabolism.  

PubMed

Mass spectrometry has been established as a powerful and versatile technique for studying cellular metabolism. Applications range from profiling of metabolites to accurate quantification and tracing of stable isotopes through the biochemical reaction network. Despite broad coverage of central carbon metabolism, most methods fail to provide accurate assessments of the ?-keto acids oxaloacetic acid, pyruvate, and glyoxylate because these compounds are highly reactive and degraded during sample processing and mass spectrometric measurement. We present a derivatization procedure to chemically stabilize these compounds readily during quenching of cellular metabolism. Stable derivatives were analyzed by ultrahigh pressure liquid chromatography coupled tandem mass spectrometry to accurately quantify the abundance of ?-keto acids in biological matrices. Eventually, we demonstrated that the developed protocol is suited to measure mass isotopomers of these ?-keto acids in tracer studies with stable isotopes. In conclusion, the here described method fills one of the last technical gaps for metabolomics investigations of central carbon metabolism. PMID:24533614

Zimmermann, Michael; Sauer, Uwe; Zamboni, Nicola

2014-03-18

267

Stable carbon isotopic compositions of organic acids in total suspended particles and dusts from Guangzhou, China  

NASA Astrophysics Data System (ADS)

Stable carbon isotopic compositions of individual organic acids were determined in total suspended particles and dusts from Guangzhou. The ? 13C values of high molecular weight n-alkanoic acids (C 20-C 28) varied from -34.1‰ to -32.4‰ and tended to be heavier in summer and lighter in winter. These ? 13C values indicate that high molecular weight n-alkanoic acids were derived mainly from emission by C 3 plants. Reduced biological synthesis of high molecular weight n-alkanoic acids in winter may be the reason for the light carbon isotopic composition. The ? 13C values of low molecular weight n-alkanoic acids (C 10-C 18) changed from -31.7‰ to -30.3‰ and exhibited a reverse seasonal trend, i.e., heavier in winter and lighter in summer. Slightly heavier ? 13C values of low molecular weight n-alkanoic acids than those of high molecular weight n-alkanoic acids suggested that they may be emitted from blended sources, e.g., anthropogenic sources and vegetation waxes. Lighter ? 13C values in summer may be attributed to relatively low anthropogenic sources and high botanic sources in summer. Dicarboxylic acids and aromatic acids have been proposed as secondary products from photochemical degradation. The average ? 13C values of dicarboxylic acids and aromatic acids were heavier, and ranged from -25.2‰ to -22.9‰ and from -30.0‰ to -27.6‰, respectively. Both dicarboxylic acids and aromatic acids displayed the same temporal variations in the ? 13C values, i.e., negative ? 13C in the summer samples and positive in the winter samples, which may be controlled by photochemical reactions; they are generally severe in winter in Guangzhou under the monsoon weather system. The heaviest ? 13C values were observed in dicarboxylic acids, indicating that dicarboxylic acids were formed by fast and more complete oxidation reactions. These results indicate that the stable carbon isotopic composition of organic acids may provide important information about sources and photochemical reactions of organic matter in the atmosphere.

Ma, Shexia; Peng, Ping'an; Song, Jianzhong; Zhao, Jinping; He, Lulu; Sheng, Guoying; Fu, Jiamo

2010-10-01

268

Production of monoolein from oleic acid and glycerol in supercritical carbon dioxide media: A kinetic approach  

Microsoft Academic Search

Esterification of free fatty acids (FFA) with glycerol in supercritical carbon dioxide (SC-CO2) media to produce designer monoacylglycerols (MAG) for food, cosmetic, and pharmaceutical industries, was conducted to elucidate the reaction kinetics and provide the reaction mechanism. Reactions were conducted in SC-CO2 at 10–30MPa, 170–250°C in a batch stirred reactor using an anhydrous glycerol to oleic acid initial molar ratio

Paul H. L. Moquin; Feral Temelli

2008-01-01

269

Inhibition of carbon steel corrosion by azathione derivatives in organic acid solutions  

Microsoft Academic Search

Purpose – The purpose of this paper is to investigate the inhibitive effect of azathiones, namely cyclopentyl-tetrahydro-azathione, cyclohexyl-tetrahydro-azathione and isobutyl-methyl-tetrahydro-azathione on the corrosion of carbon steel in formic and acetic acid solution. The effect of inhibitor concentration, immersion time, acid concentration, and solution temperature on the inhibition efficiencies of the selected azathiones were studied systematically. Design\\/methodology\\/approach – The synthesis of

Sadaf Khan; M. Z. A. Rafiquee; Nidhi Saxena; M. A. Quraishi

2009-01-01

270

Dissociation of acetic acid in 50 mass % ethylene carbonate-water from 20 to 55°C  

Microsoft Academic Search

The dissociation constant of acetic acid in 50 mass % ethylene carbonate-water solvents has been determined at eight temperatures from 20 to 55°C by emf measurements of cells without liquid-junction containing hydrogen electrodes and silver-silver chloride electrodes. Acetic acid is weaker in the mixed solvent than in pure water. At 25°C, pK is 5.645 as compared with 4.756 in water,

J-C Hallé; Roger G. Bates

1975-01-01

271

Carbon honeycomb grids for advanced lead-acid batteries. Part I: Proof of concept  

Microsoft Academic Search

The carbon honeycomb grid is proposed as innovative solution for high energy density lead acid battery. The proof of concept is demonstrated, developing grids suitable for the small capacity, scale of valve-regulated lead acid batteries with 2.5–3Ah plates. The manufacturing of the grids, includes fast, known and simple processes which can be rescaled for mass production with a minimum, investment

Angel Kirchev; Nina Kircheva; Marion Perrin

272

Whole-body pharmacokinetics of HDAC inhibitor drugs, butyric acid, valproic acid and 4-phenylbutyric acid measured with carbon-11 labeled analogs by PET  

PubMed Central

The fatty acids, n-butyric acid (BA), 4-phenylbutyric acid (PBA) and valproic acid (VPA, 2-propylpentanoic acid) have been used for many years in the treatment of a variety of CNS and peripheral organ diseases including cancer. New information that these drugs alter epigenetic processes through their inhibition of histone deacetylases (HDACs) has renewed interest in their biodistribution and pharmacokinetics and the relationship of these properties to their therapeutic and side effect profile. In order to determine the pharmacokinetics and biodistribution of these drugs in primates, we synthesized their carbon-11 labeled analogues and performed dynamic positron emission tomography (PET) in six female baboons over 90 min. The carbon-11 labeled carboxylic acids were prepared by using 11CO2 and the appropriate Grignard reagents. [11C]BA was metabolized rapidly (only 20% of the total carbon-11 in plasma was parent compound at 5 min post injection) whereas for VPA and PBA 98% and 85% of the radioactivity was the unmetabolized compound at 30 min after their administration respectively. The brain uptake of all three carboxylic acids was very low (<0.006%ID/cc, BA>VPA>PBA), which is consistent with the need for very high doses for therapeutic efficacy. Most of the radioactivity was excreted through the kidneys and accumulated in the bladder. However, the organ biodistribution between the drugs differed. [11C]BA showed relatively high uptake in spleen and pancreas whereas [11C]PBA showed high uptake in liver and heart. Notably, [11C]VPA showed exceptionally high heart uptake possibly due to its involvement in lipid metabolism. The unique biodistribution of each of these drugs may be of relevance in understanding their therapeutic and side effect profile including their teratogenic effects. PMID:23906667

Kim, Sung Won; Hooker, Jacob M.; Otto, Nicola; Win, Khaing; Muench, Lisa; Shea, Colleen; Carter, Pauline; King, Payton; Reid, Alicia E.; Volkow, Nora D.; Fowler, Joanna S.

2013-01-01

273

Whole-body pharmacokinetics of HDAC inhibitor drugs, butyric acid, valproic acid and 4-phenylbutyric acid measured with carbon-11 labeled analogs by PET.  

PubMed

The fatty acids, n-butyric acid (BA), 4-phenylbutyric acid (PBA) and valproic acid (VPA, 2-propylpentanoic acid) have been used for many years in the treatment of a variety of CNS and peripheral organ diseases including cancer. New information that these drugs alter epigenetic processes through their inhibition of histone deacetylases (HDACs) has renewed interest in their biodistribution and pharmacokinetics and the relationship of these properties to their therapeutic and side effect profiles. In order to determine the pharmacokinetics and biodistribution of these drugs in primates, we synthesized their carbon-11 labeled analogues and performed dynamic positron emission tomography (PET) in six female baboons over 90 min. The carbon-11 labeled carboxylic acids were prepared by using (11)CO2 and the appropriate Grignard reagents. [(11)C]BA was metabolized rapidly (only 20% of the total carbon-11 in plasma was parent compound at 5 min post injection) whereas for VPA and PBA 98% and 85% of the radioactivity were the unmetabolized compound at 30 min after their administration respectively. The brain uptake of all three carboxylic acids was very low (<0.006%ID/cc, BA>VPA>PBA), which is consistent with the need for very high doses for therapeutic efficacy. Most of the radioactivity was excreted through the kidneys and accumulated in the bladder. However, the organ biodistribution between the drugs differed. [(11)C]BA showed relatively high uptake in spleen and pancreas whereas [(11)C]PBA showed high uptake in liver and heart. Notably, [(11)C]VPA showed exceptionally high heart uptake possibly due to its involvement in lipid metabolism. The unique biodistribution of each of these drugs may be of relevance in understanding their therapeutic and side effect profile including their teratogenic effects. PMID:23906667

Kim, Sung Won; Hooker, Jacob M; Otto, Nicola; Win, Khaing; Muench, Lisa; Shea, Colleen; Carter, Pauline; King, Payton; Reid, Alicia E; Volkow, Nora D; Fowler, Joanna S

2013-10-01

274

Microbial mediated formation of Fe-carbonate minerals under extreme acidic conditions  

NASA Astrophysics Data System (ADS)

Discovery of Fe-carbonate precipitation in Rio Tinto, a shallow river with very acidic waters, situated in Huelva, South-western Spain, adds a new dimension to our understanding of carbonate formation. Sediment samples from this low-pH system indicate that carbonates are formed in physico-chemical conditions ranging from acid to neutral pH. Evidence for microbial mediation is observed in secondary electron images (Fig. 1), which reveal rod-shaped bacteria embedded in the surface of siderite nanocrystals. The formation of carbonates in Rio Tinto is related to the microbial reduction of ferric iron coupled to the oxidation of organic compounds. Herein, we demonstrate for the first time, that Acidiphilium sp. PM, an iron-reducing bacterium isolated from Rio Tinto, mediates the precipitation of siderite (FeCO3) under acidic conditions and at a low temperature (30°C). We describe nucleation of siderite on nanoglobules in intimate association with the bacteria cell surface. This study has major implications for understanding carbonate formation on the ancient Earth or extraterrestrial planets.

Sánchez-Román, Mónica; Fernández-Remolar, David; Amils, Ricardo; Sánchez-Navas, Antonio; Schmid, Thomas; Martin-Uriz, Patxi San; Rodríguez, Nuria; McKenzie, Judith A.; Vasconcelos, Crisogono

2014-04-01

275

Preparation and electrochemical properties of pitch-based carbon foam as current collectors for lead acid batteries  

Microsoft Academic Search

Pitch-based carbon foam with large pore size in the cell walls was prepared and evaluated as possible current collectors of lead acid batteries. Cyclic voltammetry and galvanostatic charge–discharge experiments were performed on the material to evaluate its electrochemical properties. The carbon foam is electrochemically stable in the voltage range where the negative electrodes of lead acid batteries operate, while oxygen

Ya Chen; Bai-Zhen Chen; Xi-Chang Shi; Hui Xu; Wei Shang; Yan Yuan; Lu-Ping Xiao

2008-01-01

276

Graphene-carbon nanotube composite aerogel for selective detection of uric acid  

NASA Astrophysics Data System (ADS)

Graphene and single-walled carbon nanotube (SWNT) composite aerogel has been prepared by hydrothermal synthesis. The restacking of graphene is effectively reduced by SWNTs inserted in between graphene layers in order to make available more active sites and reactive surface area. Electrochemical experiments show that the graphene-SWNT composite electrode has superior catalytic performance in selective detection of uric acid (UA).

Zhang, Feifei; Tang, Jie; Wang, Zonghua; Qin, Lu-Chang

2013-12-01

277

Carbon isotope composition of low molecular weight hydrocarbons and monocarboxylic acids from Murchison meteorite  

Microsoft Academic Search

Carbon isotopic compositions have been measured for individual hydrocarbons and monocarboxylic acids from the Murchison meteorite, a C2 carbonaceous chondrite which fell in Australia in 1969. With few exceptions, notably benzene, the volatile products are substantially isotopically heavier than their terrestrial counterparts, signifying their extraterrestrial origin. For both classes of compounds, the ratio of C-13 to C-12 decreases with increasing

George Yuen; Neal Blair; D. J. Des Marais; Sherwood Chang

1984-01-01

278

Improved Norway spruce somatic embryo development through the use of abscisic acid combined with activated carbon  

Microsoft Academic Search

The combination of abscisic acid (ABA) and activated carbon increased Norway spruce (Picea abies L., Karst.) cotyledonary somatic embryo yields, increased the number of genotypes forming cotyledonary embryos, caused embryos to form that exhibited improved maturation characteristics, and reduced embryo production costs. Somatic embryos increased in size, showed larger apical regions, became more zygotic-like in shape, and showed higher percentages

G. S. Pullman; P. K. Gupta; R. Timmis; C. Carpenter; M. Kreitinger; E. Welty

2005-01-01

279

FATTY ACID STABLE ISOTOPE INDICATORS OF MICROBIAL CARBON SOURCE IN TROPICAL SOILS  

EPA Science Inventory

The soil microbial community plays an important role in tropical ecosystem functioning because of its importance in the soil organic matter (SOM) cycle. We have measured the stable carbon isotopic ratio (delta13C) of individual phospholipid fatty acids (PLFAs) in a variety of tr...

280

Characterization of the origin of coalbed gases in southeastern Illinois Basin by compound-specific carbon and hydrogen stable isotope ratios  

USGS Publications Warehouse

Coalbed gases and waters from exploratory and production gas wells in the southeastern Illinois Basin were sampled to assess geochemically the origin of coalbed gases, with an emphasis on the Springfield and Seelyville Coal Members that are commercially targeted for coalbed methane production in Indiana. On-line analyses of hydrocarbon gases methane to butanes (C1, C2, C3, n-C4, i-C4) and CO2 yielded gas concentrations, plus ??D and ??13C values. The low thermal maturity of Indiana coals with vitrinite reflectance R0 ??? 0.6% is in agreement with an overwhelmingly biogenic isotopic signature of coalbed gases containing ???96% methane generated via bacterial CO2-reduction. In contrast, thermogenic gas was generated in the stratigraphically equivalent coal beds in western Kentucky's Rough Creek Graben zone where higher maturities of up to R0 ??? 0.8% were reached owing to tectonic and hydrothermal activity. No secondary biogenic methane was observed in more mature western Kentucky coal beds where greater burial depth limits the recharge of meteoric water. Biogenic and thermogenic coalbed gases represent two end-members that are compositionally and isotopically distinct. Microbial biodegradation of thermogenic C2+ hydrocarbon gases in Indiana coal beds preferentially targets C3 and introduces isotope fractionation whereby remaining C3 is enriched in deuterium and 13C.

Strapoc, D.; Mastalerz, M.; Eble, C.; Schimmelmann, A.

2007-01-01

281

Stable carbon isotopic compositions of total carbon, dicarboxylic acids and glyoxylic acid in the tropical Indian aerosols: Implications for sources and photochemical processing of organic aerosols  

NASA Astrophysics Data System (ADS)

The tropical Indian aerosols (PM10) collected on day- and nighttime bases in winter and summer, 2007 from Chennai (13.04°N; 80.17°E) were studied for stable carbon isotopic compositions (?13C) of total carbon (TC), individual dicarboxylic acids (C2-C9) and glyoxylic acid (?C2). ?13C values of TC ranged from -23.9‰ to -25.9‰ (-25.0 ± 0.6‰; n = 49). Oxalic (C2) (-17.1 ± 2.5‰), malonic (C3) (-20.8 ± 1.8‰), succinic (C4) (-22.5 ± 1.5‰) and adipic (C6) (-20.6 ± 4.1‰) acids and ?C2 acid (-22.4 ± 5.5‰) were found to be more enriched with 13C compared to TC. In contrast, suberic (C8) (-29.4 ± 1.8‰), phthalic (Ph) (-30.1 ± 3.5‰) and azelaic (C9) (-28.4 ± 5.8‰) acids showed smaller ?13C values than TC. Based on comparisons of ?13C values of TC in Chennai aerosols to those (-24.7 ± 2.2‰) found in unburned cow-dung samples collected from Chennai and isotopic signatures of the particles emitted from point sources, we found that biofuel/biomass burning are the major sources of carbonaceous aerosols in South and Southeast Asia. The decrease in ?13C values of C9 diacid by about 5‰ from winter to summer suggests that tropical plant emissions also significantly contribute to organic aerosol in this region. Significant increase in ?13C values from C4 to C2 diacids in Chennai aerosols could be attributed for their photochemical processing in the tropical atmosphere during long-range transport from source regions.

Pavuluri, Chandra Mouli; Kawamura, Kimitaka; Swaminathan, T.; Tachibana, Eri

2011-09-01

282

Catalytic NO reduction with NH 3 over carbons modified by acid oxidation and by metal impregnation and its kinetic studies  

Microsoft Academic Search

The catalytic effects of carbon in NO reduction with NH3 at low temperatures (<200°C) were examined using mineral matter free carbon derived from phenol–formaldehyde resin. The carbon was found to have little catalytic activity in the reaction, in contrary to other previous studies. The activity was considerably enhanced by oxidation with nitric acid and exceedingly enhanced upon impregnation with Cu

Li-Yeh Hsu; Hsisheng Teng

2001-01-01

283

Effect of Mild Nitric Acid Oxidation on Dispersability, Size, and Structure of Single-Walled Carbon Nanotubes  

E-print Network

on their intended use. Introduction Oxidation of carbon nanotubes is a basic technique for their chemicalEffect of Mild Nitric Acid Oxidation on Dispersability, Size, and Structure of Single-Walled Carbon, 2007. ReVised Manuscript ReceiVed August 29, 2007 Oxidation of single-walled carbon nanotubes (SWNTs

Resasco, Daniel

284

Collagen tissue treated with chitosan solutions in carbonic acid for improved biological prosthetic heart valves.  

PubMed

Calcification of bovine pericardium dramatically shortens typical lifetimes of biological prosthetic heart valves and thus precludes their choice for younger patients. The aim of the present work is to demonstrate that the calcification is to be mitigated by means of treatment of bovine pericardium in solutions of chitosan in carbonic acid, i.e. water saturated with carbon dioxide at high pressure. This acidic aqueous fluid unusually combines antimicrobial properties with absolute biocompatibility as far as at normal pressure it decomposes spontaneously and completely into H2O and CO2. Yet, at high pressures it can protonate and dissolve chitosan materials with different degrees of acetylation (in the range of 16-33%, at least) without any further pretreatment. Even exposure of the bovine pericardium in pure carbonic acid solution without chitosan already favours certain reduction in calcification, somewhat improved mechanical properties, complete biocompatibility and evident antimicrobial activity of the treated collagen tissue. The reason may be due to high extraction ability of this peculiar compressed fluidic mixture. Moreover, exposure of the bovine pericardium in solutions of chitosan in carbonic acid introduces even better mechanical properties and highly pronounced antimicrobial activity of the modified collagen tissue against adherence and biofilm formation of relevant Gram-positive and Gram-negative strains. Yet, the most important achievement is the detected dramatic reduction in calcification for such modified collagen tissues in spite of the fact that the amount of the thus introduced chitosan is rather small (typically ca. 1wt.%), which has been reliably detected using original tritium labelling method. We believe that these improved properties are achieved due to particularly deep and uniform impregnation of the collagen matrix with chitosan from its pressurised solutions in carbonic acid. PMID:24582232

Gallyamov, Marat O; Chaschin, Ivan S; Khokhlova, Marina A; Grigorev, Timofey E; Bakuleva, Natalia P; Lyutova, Irina G; Kondratenko, Janna E; Badun, Gennadii A; Chernysheva, Maria G; Khokhlov, Alexei R

2014-04-01

285

Effects of sulfuric acid treatment on the microstructure and electrochemical performance of a polyacrylonitrile (PAN)-based carbon anode  

Microsoft Academic Search

To examine whether acid treatment of a non-graphitizing hard carbon influences positively or negatively its electrochemical anodic performance, this study reports the effects of sulfuric acid treatment on the microstructural changes and electrochemical performance of PAN-based hard carbons prepared at various temperatures. It was found that PAN-based hard carbons heat treated at 900°C (TAN9) exhibit an increased reversible capacity by

Y. J. Kim; H. J. Lee; S. W. Lee; B. W. Cho; C. R. Park

2005-01-01

286

Greenhouse gases emission and carbon sequestration in agro-ecosystems under long-term no-till: implications for global warming mitigation  

NASA Astrophysics Data System (ADS)

No-till (NT) management has gained wide acceptance in US agriculture, and could contribute to global warming mitigation by offsetting fossil fuel emission. While C sequestration in NT systems is fairly well documented, the dynamics of greenhouse gases (GHG) emission is less well understood. However, the literature abounds with viewpoints and assumptions. Because of crop residue accumulation on NT surface and generally higher soil moisture, it is often assumed that production of carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) is greater in NT systems compared to conventional tillage (MP). But it is also possible that long-term implementation of NT could increase soil macro-porosity, lead to the evolution of an active population of methanotrophs, and ultimately result in enhanced CH4 uptake. Field data are needed to reconcile these conflicting assumptions. A 2-year (2009-2011) study was conducted to quantify C sequestration, and compare GHG fluxes in adjacent forest and cropland under MP and long-term NT (9, 13, 36 and 48 years). The study sites were located across Ohio on soil series with similar drainage characteristics (moderately well drained, MWD) so that duration of NT management is the experimental factor. We also included a site under NT for 48 years but located on somewhat poorly-drained soil (SPD) in order to assess the impact of soil drainage. Results revealed marked effect of NT duration and soil drainage characteristics on GHG fluxes. As hypothesized, we found a positive impact of NT on CH4 uptake, but significant difference with MP management was noted at sites under NT for > 10 years. At the sites under NT for 48 years, CH4 uptake rate was 10-12 times higher in MWD than in SPD soils. When data from all sites were pooled, N2O fluxes were significantly higher under MP (2.01 mg N2O-N m-2 d-1) than under NT (0.73), but the trend varied with NT duration. While at recent (<10 y) NT sites, N2O emission was significantly lower than under MP, the reverse was observed at sites under NT for > 30 years. At these older NT sites, N2O emissions accounted for 40-60 % of the global warming potential (GWP, sum of all GHG expressed as CO2 equivalents). These findings suggest that the viability of NT farming as a climate warming mitigation strategy hinges on the adoption of N fertilizer management practices (timing, amount, type and method of application) that minimize N2O emissions from cropland under long-term NT.

Jacinthe, P.; Dick, W. A.; Lal, R.; Shrestha, R. K.; Bilen, S.

2011-12-01

287

One carbon metabolism in anaerobic bacteria: Regulation of carbon and electron flow during organic acid production  

SciTech Connect

This reporting period, progress is reported on the following: metabolic pathway of solvent production in B. methylotrophicum; the biochemical mechanism for metabolic regulation of the succinate fermentation; models to understand the physiobiochemical function of formate metabolism in anaerobes and; models for understanding the influence of low pH on one carbon metabolism. (CBS)

Zeikus, J.G.; Jain, M.K.

1992-01-01

288

Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic  

SciTech Connect

Our research is aimed at investigating several technical issues associated with carbon dioxide sequestration in calcium carbonate sediments below the sea floor through laboratory experiments and chemical transport modeling. Our goal is to evaluate the basic feasibility of this approach, including an assessment of optimal depths, sediment types, and other issues related to site selection. The results of our modeling efforts were published this past summer in the Proceedings of the National Academy of Sciences. We are expanding on that work through a variety of laboratory and modeling efforts. In the laboratories at Columbia and at Harvard, we are studying the flow of liquid carbon dioxide and carbon dioxide-water mixtures through calcium carbonate sediments to better understand the geomechanical and structural stability of the sediments during and after injection. We are currently preparing the results of these findings for publication. In addition, we are investigating the kinetics of calcium carbonate dissolution in the presence of CO{sub 2}-water fluids, which is a critical feature of the system as it allows for increased permeability during injection. We are also investigating the possibility of carbon dioxide hydrate formation in the pore fluid, which might complicate the injection procedure by reducing sediment permeability but might also provide an upper seal in the sediment-pore fluid system, preventing release of CO{sub 2} into the deep ocean, particularly if depth and temperature at the injection point rule out immediate hydrate formation. This is done by injecting liquid CO{sub 2} into various types of porous media, and then monitoring the changes in permeability. Finally, we are performing an economic analysis to estimate costs of drilling and gas injection, site monitoring as well as the availability of potential disposal sites with particular emphasis on those sites that are within the 200-mile economic zone of the United States. We present some preliminary results from these analyses. A paper discussing the site selection based on data from the Ocean Drilling Program and Deep Sea Drilling Program is currently in preparation.

Daniel P. Schrag

2006-07-14

289

Electrochemical evaluation of ferrocene carboxylic acids confined on surfactant–clay modified glassy carbon electrodes: oxidation of ascorbic acid and uric acid  

Microsoft Academic Search

We report on the electrochemical behavior of chemically modified glassy carbon (GC) electrodes by using surfactant\\/clay films, [cetyltrimethylammonium bromide (CTAB)\\/hydrotalcite-like], containing ferrocenecarboxylic (FC) or ferrocenedicarboxylic (FDC) acid. The results show that the surfactant molecules incorporated into the clay could increase the permeability and the positive surface of the film. The FDC–CTAB–clay–GC modified electrode showed greater stability and redox electroactivity than

Lenys Fernández; Hermes Carrero

2005-01-01

290

Competition between humic acid and carbonates for rare earth elements complexation.  

PubMed

The competitive binding of rare earth elements (REE) to humic acid (HA) and carbonates was studied experimentally at various pH and alkalinity values by combining ultrafiltration and inductively coupled plasma mass spectrometry techniques. The results show that the REE species occur as binary humate or carbonate complexes but not as ternary REE-carbonate-humate as previously proposed. The results also reveal the strong pH and alkalinity dependence of the competition as well as the existence of a systematic fractionation across the REE series. Specifically, carbonate complexation is at a maximum at pH 10 and increase with increasing alkalinity and with the atomic number of the REE (LuCO(3)>LaCO(3)). Modeling of the data using Model VI and recently published stability constants for complexation of REE by humic acid well reproduced the experimental data, confirming the ability of Model VI to accurately determine REE speciation in natural waters. This modeling also confirms the reliability of recently published stability constants. This work shed more light not only on the competition between carbonates and HA for REE complexation but also on the reliability of WHAM 6 and Model VI for calculating the speciation of REE with organic matter in alkaline organic-rich water. PMID:17052726

Pourret, Olivier; Davranche, Mélanie; Gruau, Gérard; Dia, Aline

2007-01-01

291

Fabrication and characterization of polylactic acid and polylactic acid/multi-walled carbon nanotube nanofibers through centrifugal spinning  

NASA Astrophysics Data System (ADS)

Biocompatible polymer nanofibers hold great potential in the biomedical engineering field. Their biodegradable nature and enhanced properties could help solve a wide array of health related problems, particularly in the areas of tissue regeneration, drug delivery, and biosensor design. The novel Forcespinning™ method allows the production of submicron fibers without many of the drawbacks found in electrospinning, while also providing a substantial increase in fiber production. The aim of the study was to utilize this method to fabricate non-woven nanofibrous mats composed of polylactic acid (PLA) and polylactic acid/multi-walled carbon nanotube composite fibers. The morphology, thermal properties, and crystalline structure of the resulting nanofibers were then characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and X-Ray Diffraction (XRD).

Patlan, Richard

292

Nomex polyaramid as a precursor for activated carbon fibres by phosphoric acid activation. Temperature and time effects  

Microsoft Academic Search

This work concerns the preparation of activated carbon fibres (ACFs) by phosphoric acid activation of Nomex [poly(m-phenylene isophthalamide)] polyaramid fibres. The transformations involved in Nomex pyrolysis in the presence of phosphoric acid as a function of temperature were studied by infrared spectroscopy. Then, ACFs were prepared by impregnating Nomex with phosphoric acid, followed by pyrolysis and washing with water. The

Fabián Suárez-García; Amelia Martínez-Alonso; Juan M. D. Tascón

2004-01-01

293

Thresholds for Survival of Brown Trout during the Spring Flood Acid Pulse in Streams High in Dissolved Organic Carbon  

E-print Network

Thresholds for Survival of Brown Trout during the Spring Flood Acid Pulse in Streams High on the impact of acidity on brown trout, the streams in this study were high in dissolved organic carbon (DOC), and as a result organic acids play a primary role in controlling pH. During the spring flood period DOC

Buffam, Ishi

294

The effect of phosphoric acid on the absorption of carbon dioxide into solutions of methyldiethanolamine  

E-print Network

the coabsorption of COz into MDEA solutions. The absorption of carbon dioxide into aqueous MDEA solutions is a mass- transfer process from the gas phase to the liquid phase followed by a chemical reaction. Several researchers, including Tomcej et ah (1989... the carbon dioxide reaction. The objective of this study is to determine whether the addition of small amounts of phosphoric acid (HsPO4) to aqueous MDEA will reduce the rate of CO2 absorption. This will be accomplished by determining comparative kinetic...

Cordi, Eric Marshall

2012-06-07

295

Microwave-assisted polyol synthesis of carbon nitride dots from folic acid for cell imaging  

PubMed Central

A green, one-step microwave-assisted polyol synthesis was employed to prepare blue luminescent carbon nitride dots (CNDs) using folic acid molecules as both carbon and nitrogen sources. The as-prepared CNDs had an average size of around 4.51 nm and could be well dispersed in water. Under excitation at 360 nm, the CNDs exhibited a strong blue luminescence and the quantum yield was estimated to be 18.9%, which is greater than that of other reported CNDs. Moreover, the CNDs showed low cytotoxicity and could efficiently label C6 glioma cells, demonstrating their potential in cell imaging. PMID:25382977

Guan, Weiwei; Gu, Wei; Ye, Ling; Guo, Chenyang; Su, Su; Xu, Pinxiang; Xue, Ming

2014-01-01

296

Process characterization and influence of alternative carbon sources and carbon-to-nitrogen ratio on organic acid production by Aspergillus oryzae DSM1863.  

PubMed

L-Malic acid and fumaric acid are C4 dicarboxylic organic acids and considered as promising chemical building blocks. They can be applied as food preservatives and acidulants in rust removal and as polymerization starter units. Molds of the genus Aspergillus are able to produce malic acid in large quantities from glucose and other carbon sources. In order to enhance the production potential of Aspergillus oryzae DSM 1863, production and consumption rates in an established bioreactor batch-process based on glucose were determined. At 35 °C, up to 42 g/L malic acid was produced in a 168-h batch process with fumaric acid as a by-product. In prolonged shaking flask experiments (353 h), the suitability of the alternative carbon sources xylose and glycerol at a carbon-to-nitrogen (C/N) ratio of 200:1 and the influence of different C/N ratios in glucose cultivations were tested. When using glucose, 58.2 g/L malic acid and 4.2 g/L fumaric acid were produced. When applying xylose or glycerol, both organic acids are produced but the formation of malic acid decreased to 45.4 and 39.4 g/L, respectively. Whereas the fumaric acid concentration was not significantly altered when cultivating with xylose (4.5 g/L), it is clearly enhanced by using glycerol (9.3 g/L). When using glucose as a carbon source, an increase or decrease of the C/N ratio did not influence malic acid production but had an enormous influence on fumaric acid production. The highest fumaric acid concentrations were determined at the highest C/N ratio (300:1, 8.44 g/L) and lowest at the lowest C/N ratio (100:1, 0.7 g/L). PMID:24604500

Ochsenreither, Katrin; Fischer, Christian; Neumann, Anke; Syldatk, Christoph

2014-06-01

297

Enhancing thermal conductivity of palmitic acid based phase change materials with carbon nanotubes as fillers  

SciTech Connect

Multi-walled carbon nanotubes (CNTs) as produced are usually entangled and not ready to be dispersed into organic matrix. CNTs were treated by mechano-chemical reaction with ball milling the mixture of potassium hydroxide and the pristine CNTs. Hydroxide radical functional groups have been introduced on the CNT surfaces, which enabled to make stable and homogeneous CNT composites. Treated CNTs were successfully dispersed into the palmitic acid matrix without any surfactant. Transient short-hot-wire apparatus was used to measure the thermal conductivities of these nanotube composites. Nanotube composites have substantially higher thermal conductivities than the base palmitic acid matrix, with the enhancement increasing with the mass fraction of CNTs in both liquid state and solid state. The enhancements of the thermal conductivity are about 30% higher than the reported corresponding values for palmitic acid based phase change nanocomposites containing 1 wt% CNTs treated by concentrated acid mixture. (author)

Wang, Jifen [School of Urban Development and Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209 (China); State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237 (China); Xie, Huaqing; Li, Yang; Chen, Lifei [School of Urban Development and Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209 (China); Xin, Zhong [State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237 (China)

2010-02-15

298

Acid Diversion in Carbonate Reservoirs Using Polymer-Based In-Situ Gelled Acids  

E-print Network

and the acid injection rate should be determined based on the expected shear rate in the formation. A core flood experiment is recommended to confirm optimum injected rate. Well flow back is needed to minimize the residual gel inside the formation. The data...

Gomaa, Ahmed Mohamed Mohamed

2012-07-16

299

Optimization of modified carbon paste electrode with multiwalled carbon nanotube/ionic liquid/cauliflower-like gold nanostructures for simultaneous determination of ascorbic acid, dopamine and uric acid.  

PubMed

We describe the modification of a carbon paste electrode (CPE) with multiwalled carbon nanotubes (MWCNTs) and an ionic liquid (IL). Electrochemical studies by using a D-optimal mixture design in Design-Expert software revealed an optimized composition of 60% graphite, 14.2% paraffin, 10.8% MWCNT and 15% IL. The optimal modified CPE shows good electrochemical properties that are well matched with model prediction parameters. In the next step, the optimized CPE was modified with gold nanostructures by applying a double-pulse electrochemical technique. The resulting electrode was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and electrochemical impedance spectroscopy. It gives three sharp and well-separated oxidation peaks for ascorbic acid (AA), dopamine (DA), and uric acid (UA). The sensor enables simultaneous determination of AA, DA and UA with linear responses from 0.3 to 285, 0.08 to 200, and 0.1 to 450?M, respectively, and with 120, 30 and 30nM detection limits (at an S/N of 3). The method was successfully applied to the determination of AA, DA, and UA in spiked samples of human serum and urine. PMID:25280680

Afraz, Ahmadreza; Rafati, Amir Abbas; Najafi, Mojgan

2014-11-01

300

Fatty acid and stable carbon isotope characterization of Camelina sativa oil: implications for authentication.  

PubMed

The importance of authenticity characterization is an increasing and pressing requirement for all foods. Vegetable oil is one of the most studied foods because of its nutritional and medicinal properties in a correct diet. In this study, a total of 53 Camelina sativa samples, from all known growing areas, were chemically and isotopically characterized. The fatty acid content of camelina oil was determined by gas chromatography (GC), and the ratios of stable carbon isotopes ((13)C/(12)C) of individual fatty acids and seed/bulk oil were determined by gas chromatography-combustion-stable isotope ratio mass spectrometry (GC/C/IRMS) and elemental analysis-stable isotope ratio mass spectrometry (IRMS). A total of 17 different fatty acids were detected by GC, with omega3 R-linolenic acid (C(18:3n3)) being the most abundant (29.7-40.0 wt %). Oleic acid (C(18:1n9)), linoleic acid (C(18:2n6)) and eicosenoic acid (C(20:1n9)) all belong to the second group of major fatty acids. The stable carbon isotopic values (delta(13)C) fell into a range typical for C(3) plants. The use of delta(13)C(18:2n6) vs delta(13)C(18:3n3) correlation could show cases where impurity or adulteration is suspected, whereas principal component analysis clearly separates oil samples from different continents. Preliminary results on the camelina oil authentication procedure provide a basis for the investigation of geographical origin and the further distinction between camelina and camelina refined or other, less expensive oils. PMID:19123821

Hrastar, Robert; Petrisic, Marinka G; Ogrinc, Nives; Kosir, Iztok Joze

2009-01-28

301

Cloning and characterization of four novel coral acid-rich proteins that precipitate carbonates in vitro.  

PubMed

Biomineralization is a widely dispersed and highly regulated but poorly understood process by which organisms precipitate minerals from a wide variety of elements [1]. For many years, it has been hypothesized that the biological precipitation of carbonates is catalyzed by and organized on an extracellular organic matrix containing a suite of proteins, lipids, and polysaccharides [2, 3]. The structures of these molecules, their evolutionary history, and the biophysical mechanisms responsible for calcification remain enigmatic. Despite the recognition that mineralized tissues contain proteins that are unusually rich in aspartic and glutamic acids [4-6], the role of these proteins in biomineralization remains elusive [5, 6]. Here we report, for the first time, the identification, cloning, amino acid sequence, and characterization of four highly acidic proteins, derived from expression of genes obtained from the common stony coral, Stylophora pistillata. Each of these four proteins can spontaneously catalyze the precipitation of calcium carbonate in vitro. Our results demonstrate that coral acid-rich proteins (CARPs) not only bind Ca(2+) stoichiometrically but also precipitate aragonite in vitro in seawater at pH 8.2 and 7.6, via an electrostatic interaction with protons on bicarbonate anions. Phylogenetic analysis suggests that at least one of the CARPs arose from a gene fusion. Similar, highly acidic proteins appear to have evolved several times independently in metazoans through convergence. Based purely on thermodynamic grounds, the predicted change in surface ocean pH in the next decades would appear to have minimal effect on the capacity of these acid-rich proteins to precipitate carbonates. PMID:23746634

Mass, Tali; Drake, Jeana L; Haramaty, Liti; Kim, J Dongun; Zelzion, Ehud; Bhattacharya, Debashish; Falkowski, Paul G

2013-06-17

302

AIR INFILTRATION MEASUREMENTS USING TRACER GASES: A LITERATURE REVIEW  

EPA Science Inventory

The report gives results of a literature review of air filtration measurements using tracer gases, including sulfur hexafluoride, hydrogen, carbon monoxide, carbon dioxide, nitrous oxide, and radioactive argon and krypton. Sulfur hexafluoride is the commonest tracer gas of choice...

303

Carbon dioxide laser energy disperses human papillomavirus deoxyribonucleic acid onto treatment fields.  

PubMed

The possibility of dispersing viral deoxyribonucleic acid during carbon dioxide laser treatment of human papillomavirus-containing genital infections has been investigated with a commercially available dot blot hybridization technique. The viral ribonucleic acid probes were specific for groups of human papillomavirus types 6/11, 16/18, and 31/33/35. Laser energy was delivered by continuous-wave mode and the plume of smoke was evacuated by a vacuum suction system. Samples were taken with Dacron swabs from lesional tissues of 43 patients as well as from the treated areas and from the 5 cm surrounding normal skin before and after laser vaporization. Human papillomavirus deoxyribonucleic acid was identified in swabs from 34 of 43 (79%) lesional tissues and 7 of 43 (16%) treatment fields. Although a trend for higher human papillomavirus deoxyribonucleic acid positivity in laser margins after therapy (7/43, 16%) than before (4/43, 9%) was observed, the rates were not statistically significant. It is concluded that carbon dioxide laser energy disperses human papillomavirus deoxyribonucleic acid onto treatment fields and the adjacent normal epithelium. Viral contamination of treated areas may be reduced by positioning the fume evacuator within 1 cm of the field of laser vaporization and cleaning the treated areas and surrounding tissue after therapy. PMID:2171340

Ferenczy, A; Bergeron, C; Richart, R M

1990-10-01

304

Carbon quantum dots with photo-generated proton property as efficient visible light controlled acid catalyst  

NASA Astrophysics Data System (ADS)

Developing light-driven acid catalyst will be very meaningful for the controlled-acid catalytic processes towards a green chemical industry. Here, based on scanning electrochemical microscopy (SECM) and ?pH testing, we demonstrate that the 5-10 nm carbon quantum dots (CQDs) synthesized by electrochemical ablation of graphite have strong light-induced proton properties under visible light in solution, which can be used as an acid catalyst. The 5-10 nm CQDs' catalytic activity is strongly dependent on the illumination intensity and the temperature of the reaction system. As an effective visible light driven and controlled acid-catalyst, 5-10 nm CQDs can catalyze a series of organic reactions (esterification, Beckmann rearrangement and aldol condensation) with high conversion (34.7-46.2%, respectively) in water solution under visible light, while the 1-4 nm CQDs and 10-2000 nm graphite do not have such excellent catalytic activity. The use of 5-10 nm CQDs as a light responsive and controllable photocatalyst is truly a novel application of carbon-based nanomaterials, which may significantly push research in the current catalytic industry, environmental pollution and energy issues.Developing light-driven acid catalyst will be very meaningful for the controlled-acid catalytic processes towards a green chemical industry. Here, based on scanning electrochemical microscopy (SECM) and ?pH testing, we demonstrate that the 5-10 nm carbon quantum dots (CQDs) synthesized by electrochemical ablation of graphite have strong light-induced proton properties under visible light in solution, which can be used as an acid catalyst. The 5-10 nm CQDs' catalytic activity is strongly dependent on the illumination intensity and the temperature of the reaction system. As an effective visible light driven and controlled acid-catalyst, 5-10 nm CQDs can catalyze a series of organic reactions (esterification, Beckmann rearrangement and aldol condensation) with high conversion (34.7-46.2%, respectively) in water solution under visible light, while the 1-4 nm CQDs and 10-2000 nm graphite do not have such excellent catalytic activity. The use of 5-10 nm CQDs as a light responsive and controllable photocatalyst is truly a novel application of carbon-based nanomaterials, which may significantly push research in the current catalytic industry, environmental pollution and energy issues. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03996j

Li, Haitao; Liu, Ruihua; Kong, Weiqian; Liu, Juan; Liu, Yang; Zhou, Lei; Zhang, Xing; Lee, Shuit-Tong; Kang, Zhenhui

2013-12-01

305

Effects of Acid Additives on Spent Acid Flowback through Carbonate Cores  

E-print Network

TABLE 4.5b-ACID FORMULATION (INDIANA LIMESTONE; FA-CI) 1 Water 189 cc 2 HCl (15 wt%) 111 cc 3 NaI (5 wt%) 15.8 g 4 FA-CI (2 wt%) 6.3 g TABLE 4.5c-FLOWBACK PARAMETERS (INDIANA LIMESTONE;FA-CI) 1 Back pressure 300 psi 2 Overburden pressure...-ACID FORMULATION (INDIANA LIMESTONE; MI-CI) 1 Water 189 cc 2 HCl (15 wt%) 111 cc 3 NaI (5 wt%) 15.8 g 4 MI-CI (2 wt%) 6.3 g TABLE 4.6c-FLOWBACK PARAMETERS (INDIANA LIMESTONE; MI-CI) 1 Back pressure 300 psi 2 Overburden pressure 1500 psi 3 Inlet pr...

Nasir, Ehsaan Ahmad

2012-07-16

306

Electrochemical and XPS studies of decylamides of ?-amino acids adsorption on carbon steel in acidic environment  

NASA Astrophysics Data System (ADS)

Corrosion inhibition of steel in hydrochloric acid by decylamides of ?-amino acids derivatives was studied using gravimetric and electrochemical techniques. Protection efficiencies of 90% were obtained with 100 ppm of tyrosine and glycine derivatives, while alanine and valine derivatives reached only 80%. The order of increasing inhibition efficiency was correlated with the modification of the molecular structure of inhibitors. Potentiodynamic polarization curves indicated that both the decylamide of tyrosine and glycine acted primarily as anodic type inhibitors, whereas the decylamide of alanine and valine were of the cathodic type. Thermodynamic parameters and Flory-Huggins adsorption isotherms described the experimental findings. The number of active sites, equilibrium constant, enthalpy and change of free energy were computed for all inhibitors studied. This information suggested that organic molecules were adsorbed and displaced water molecules from the steel surface. X-ray photoelectron spectroscopy confirmed that species of N, C and O interacted with steel to form a continuous protective film.

Olivares, O.; Likhanova, N. V.; Gómez, B.; Navarrete, J.; Llanos-Serrano, M. E.; Arce, E.; Hallen, J. M.

2006-02-01

307

ZnO/carbon nano composite: Effective catalyst for the photo degradation of Acid Blue 113  

NASA Astrophysics Data System (ADS)

Zinc oxide carbon composite (ZnO/C) was synthesized by self - propagating solution combustion method. This method enabled the addition of carbon insitu to the metal oxide. The composite synthesized were characterised by XRD, SEM and BET analysis. This composite was used for the removal of organic pollutants such as the dye Acid blue 113 by UV irradiation performed in a batch reactor. The influence of various experimental parameters such as the initial concentration of the dye, Concentration of the photocatalyst and the pH on the photo catalytic degradation under UV irradiation was studied. It has been observed that the degradation of the dye to be more pronounced in neutral medium. The degradation of acid blue 113 was found to increase with ZnO/C composites loading and decreases with decrease in concentration of the composite.

Sunitha, S.; Rao, A. Nageswara; Karthikeyan, J.; Krithiga, T.

2013-06-01

308

Carbon honeycomb grids for advanced lead-acid batteries. Part I: Proof of concept  

NASA Astrophysics Data System (ADS)

The carbon honeycomb grid is proposed as innovative solution for high energy density lead acid battery. The proof of concept is demonstrated, developing grids suitable for the small capacity, scale of valve-regulated lead acid batteries with 2.5-3 Ah plates. The manufacturing of the grids, includes fast, known and simple processes which can be rescaled for mass production with a minimum, investment costs. The most critical process of green composite carbonisation by heating in inert, atmosphere from 200 to 1000 °C takes about 5 h, guaranteeing the low cost of the grids. An AGM-VRLA, cell with prototype positive plate based on the lead-2% tin electroplated carbon honeycomb grid and, conventional negative plates is cycled demonstrating 191 deep cycles. The impedance spectroscopy, measurements indicate the grid performance remains acceptable despite the evolution of the corrosion, processes during the cycling.

Kirchev, Angel; Kircheva, Nina; Perrin, Marion

2011-10-01

309

Isolation of anacardic acid from natural cashew nut shell liquid (CNSL) using supercritical carbon dioxide.  

PubMed

Solvent extracted cashew nut shell liquid (CNSL), conventionally known as natural CNSL, is a mixture of several alkenyl phenols. One of these alkenyl phenols is anacardic acid, which is present at the highest concentration. In view of anticipated industrial applications of anacardic acid, the objective of this work was to isolate anacardic acid from natural CNSL by supercritical carbon dioxide (scCO 2). In this study, the solubility data for natural CNSL in scCO 2 under a range of operating conditions of pressure (100, 200, and 300 bar), temperature (40 and 50 degrees C), and CO 2 flow rate (5, 10, and 15 g min (-1)) were established. The best scCO 2 working conditions were found to be 50 degrees C and 300 bar at a flow rate of 5 g min (-1) CO 2. Using 3 g of sample (CNSL/solid adsorbent = 1/2) under these scCO 2 conditions, it was possible to quantitatively isolate high purity anacardic acid from crude natural CNSL (82% of total anacardic acid) within 150 min. The anacardic acid isolated by scCO 2 was analyzed by different spectroscopic techniques (UV-vis, FT-IR, and (1)H NMR) and HPLC analysis, indicating that the anacardic acid isolated by scCO 2 has better quality than that obtained through a conventional method involving several chemical conversion steps. PMID:18811166

Philip, Joseph Y N; Da Cruz Francisco, José; Dey, Estera S; Buchweishaija, Joseph; Mkayula, Lupituko L; Ye, Lei

2008-10-22

310

Planetary rover robotics experiment in education: carbonate rock collecting experiment of the Husar-5 rover of the Szechenyistvan high school, Sorpon, Hungary  

NASA Astrophysics Data System (ADS)

The new experiment for the Husar-5 educational space probe rover consists of steps of the technology of procedure of finding carbonate specimens among the rocks on the field. 3 main steps were robotized: 1) identification of carbonate by acid test, 2) measuring the gases liberated by acid, and 3)magnetic test.

Lang, A.; Prajczer, P.; Bérczi, Sz.

2013-09-01

311

Inhibition of the corrosion of low carbon steel in acidic solution by selected polyelectrolytes and polymers  

Microsoft Academic Search

The inhibiting effects of 2,6-ionen and 2,10-ionen type polyvinylbenzyltrimethylammonium chloride, and latex, on low carbon steel in hydrochloric acid solution was investigated by potentiodynamic polarisation measurements and impedance measurement techniques over the temperature range of 20-60°C at different inhibitor concentrations. It was found that the inhibition efficiencies increased with increasing inhibitor concentration. The degree of shift in Ecorr values, together

G. Bereket; A. Yurt; H. Türk

2003-01-01

312

Formation of bamboo-shape carbon nanotubes by controlled rapid decomposition of picric acid  

Microsoft Academic Search

In the presence of catalysts, carbon nanotubes (CNTs) can efficiently grow in the environment generated by the rapid decomposition of normal explosives. Controlling the reaction parameters of a mixture of picric acid (PA) with cobalt acetate and paraffin can lead to a well-defined morphology of CNTs. The formation of bamboo-shape tubes is favorable at relatively high Co(AC)2\\/PA and paraffin\\/PA ratios.

Yi Lu; Zhenping Zhu; Dangsheng Su; Di Wang; Zhenyu Liu; Robert Schlögl

2004-01-01

313

Electrochemical generation of manganese (III) at glassy carbon electrode in acetic acid  

Microsoft Academic Search

Conditions were established for the electrochemical generation of manganese(III) at glassy carbon in acetic acid. In the oxidation of manganese-(II) in potassium acetate supporting electrolyte high current efficiencies were achieved in a wide range of current densities at the working electrode, whereas in the presence of sodium perchlorate a successful generation of manganese(III) could be performed only at low current

Tibor J. Pastor; Vojka V. Antonijevi?

1990-01-01

314

The erosion of carbonate stone by acid rain: Laboratory and field investigations  

USGS Publications Warehouse

One of the goals of research on the effects of acidic deposition on carbonate stone surfaces is to define the incremental impact of acidic deposition relative to natural weathering processes on the rate of carbonate stone erosion. If rain that impacts carbonate stone surfaces is resident on the surface long enough to approach chemical equilibrium, the incremental effect of hydrogen ion is expected to be small (i.e., 6% for a rain of pH 4.0). Under nonequilibrium (i.e., high flow rate) conditions, kinetic considerations suggest that the incremental effect of hydrogen ion deposition could be quite significant. Field run-off experiments involving the chemical analysis of rain collected from inclined stone slabs have been used to evaluate stone dissolution processes under ambient conditions of wet and dry deposition of acidic species. The stoichiometry of the reaction of stone with hydrogen ion is difficult to define from the field data due to scatter in the data attributed to hydrodynamic effects. Laboratory run-off experiments show that the stoichiometry is best defined by a reaction with H+ in which CO2 is released from the system. The baseline effect caused by water in equilibrium with atmospheric CO2 is identical in the field and in laboratory simulation. The experiments show that the solutions are close enough to equilibrium for the incremental effect of hydrogen ion to be minor (i.e., 24% for marble for a rain of pH 4.0) relative to dissolution due to water and carbonic acid reactions. Stone erosion rates based on physical measurement are approximately double the recession rates that are due to dissolution (estimated from the observed calcium content of the run-off solutions). The difference may reflect the loss of granular material not included in recession estimates based on the run-off data. Neither the field nor the laboratory run-off experiments indicate a pH dependence for the grain-removal process.

Baedecker, P.A.; Reddy, M.M.

1993-01-01

315

Pitch-based carbon foam electrodeposited with lead as positive current collectors for lead acid batteries  

Microsoft Academic Search

Lead electrodeposited carbon foam (LCF), whose substrate was made from pitch by a template method, was investigated as possible\\u000a positive current collectors for lead acid batteries. Scanning electron microscopy, cyclic voltammetry, and galvanostatic charge–discharge\\u000a tests were employed to characterize the effect of the proposed collector on the structure and electrochemical properties of\\u000a the positive active material (PAM). The LCF with

Li-Wen Ma; Bai-Zhen Chen; Ya Chen; Yan Yuan

2009-01-01

316

Influence of carbon black on the properties of plasticized poly(lactic acid) composites  

Microsoft Academic Search

Using acetyl tributyl citrate (ATBC) and poly(1,3-butylene adipate) (PBA) as the plasticizer of poly(lactic acid) (PLA) and carbon black (CB) as reinforced filler, high performance composites were prepared in melting blend. Fourier transform infrared spectroscopy revealed that the interaction existed between PLA and CB, and plasticizer could improve this interaction. The rheology showed that plasticizer could obviously improve the fluidity

Ning Wang; Xingxiang Zhang; Xiaofei Ma; Jianming Fang

2008-01-01

317

Salicylhydroxamic acid (SHAM) inhibition of the dissolved inorganic carbon concentrating process in unicellular green algae  

SciTech Connect

Rates of photosynthetic O{sub 2} evolution, for measuring K{sub 0.5}(CO{sub 2} + HCO{sub 3}{sup {minus}}) at pH 7, upon addition of 50 micromolar HCO{sub 3}{sup {minus}} to air-adapted Chlamydomonas, Dunaliella, or Scenedesmus cells, were inhibited up to 90% by the addition of 1.5 to 4.0 millimolar salicylhydroxamic acid (SHAM) to the aqueous medium. The apparent K{sub i}(SHAM) for Chlamydomonas cells was about 2.5 millimolar, but due to low solubility in water effective concentrations would be lower. Salicylhydroxamic acid did not inhibit oxygen evolution or accumulation of bicarbonate by Scenedesmus cells between pH 8 to 11 or by isolated intact chloroplasts from Dunaliella. Thus, salicylhydroxamic acid appears to inhibit CO{sub 2} uptake, whereas previous results indicate that vanadate inhibits bicarbonate uptake. These conclusions were confirmed by three test procedures with three air-adapted algae at pH 7. Salicylhydroxamic acid inhibited the cellular accumulation of dissolved inorganic carbon, the rate of photosynthetic O{sub 2} evolution dependent on low levels of dissolved inorganic carbon (50 micromolar NaHCO{sub 3}), and the rate of {sup 14}CO{sub 2} fixation with 100 micromolar ({sup 14}C)HCO{sub 3}{sup {minus}}. Salicylhydroxamic acid inhibition of O{sub 2} evolution and {sup 14}CO{sub 2}-fixation was reversed by higher levels of NaHCO{sub 3}. Thus, salicylhydroxamic acid inhibition was apparently not affecting steps of photosynthesis other than CO{sub 2} accumulation. Although salicylhydroxamic acid is an inhibitor of alternative respiration in algae, it is not known whether the two processes are related.

Goyal, A.; Tolbert, N.E. (Michigan State Univ., East Lansing (USA))

1990-03-01

318

Influence of unsaturated carbonic acids on hemocompatibility and cytotoxicity of poly-vinylacetate based co-polymers  

Microsoft Academic Search

The aim of this study was to investigate hemocompatibility and cytotoxicity properties of synthetic polymer coatings containing\\u000a various unsaturated carbonic acids with vinylacetate. Co-polymers of vinylacetate and crotonic acid (CA), maleic acid (MA),\\u000a and itaconic acid (IA) were made. The materials were characterized in terms of their adhesion to metal supports (titanium\\u000a and stainless steel) as well as hemocompatibility (%

N. B. Tavakalyan; A. G. Karapetyan; A. S. Pogosyan; A. K. Abrahamyan; A. Corti; A. Pompella; A. Mihranyan

2010-01-01

319

Amino acid diagenesis, organic carbon and nitrogen mineralization in surface sediments from the inner Oslofjord, Norway  

SciTech Connect

Total hydrolyzed amino acids (THAA), total organic carbon (TOC), and total nitrogen (TN) have been measured in an oxic and anoxic surface sediment from the inner Oslofjord. Downcore variations of these parameters are ascribed to both diagenesis and changes in organic matter supply, the latter being most important. These changes are most prominent in the anoxic sediment, which reflects the eutrophication history of the innermost part of the fjord. Downcore, THAA content decreased from 3.8 to 2.0 mg/g (salt-free dry weight) in the oxic sediment and from 22.3 to 3.8 mg/g in the anoxic sediment. Total amino acid nitrogen varied between 17 and 34% of total nitrogen in the oxic, and 25 and 54% in the anoxic, sediment. Organic carbon and organic nitrogen accumulation rates and depth integrated mineralization rates are about three times higher in the anoxic sediment than in the oxic sediment. Recycling of amino acids accounted for 4 to 12% of the total organic carbon and 13 to 40% of the total organic nitrogen regenerated in these sediments.

Haugen, J.E. (National Inst. of Public Health, Oslo (Norway)); Lichtentaler, R. (Norwegian Inst. for Water Research, Oslo (Norway))

1991-06-01

320

Tracing Carbon Sources through Aquatic and Terrestrial Food Webs Using Amino Acid Stable Isotope Fingerprinting  

PubMed Central

Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring ?13C patterns among amino acids (?13CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that ?13CAA patterns in contrast to bulk ?13C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their ?13CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk ?13C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer ?13C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs. PMID:24069196

Larsen, Thomas; Ventura, Marc; Andersen, Nils; O'Brien, Diane M.; Piatkowski, Uwe; McCarthy, Matthew D.

2013-01-01

321

Potentially bioavailable natural organic carbon and hydrolyzable amino acids in aquifer sediments  

USGS Publications Warehouse

This study evaluated the relationship between concentrations of operationally defined potentially bioavailable organic -carbon (PBOC) and hydrolyzable amino acids (HAAs) in sediments collected from a diverse range of chloroethene--contaminated sites. Concentrations of PBOC and HAA were measured using aquifer sediment samples collected at six selected study sites. Average concentrations of total HAA and PBOC ranged from 1.96 ± 1.53 to 20.1 ± 25.6 mg/kg and 4.72 ± 0.72 to 443 ± 65.4 mg/kg, respectively. Results demonstrated a statistically significant positive relationship between concentrations of PBOC and total HAA present in the aquifer sediment (p < 0.05). Higher levels of HAA were consistently observed at sites with greater levels of PBOC and first-order decay rates. Because amino acids are known to be readily biodegradable carbon compounds, this relationship suggests that the sequential chemical extraction procedure used to measure PBOC is a useful indicator of bioavailable carbon in aquifer sediments. This, in turn, is consistent with the interpretation that PBOC measurements can be used for estimating the amount of natural organic carbon available for driving the reductive dechlorination of chloroethenes in groundwater systems.

Thomas, Lashun K.; Widdowson, Mark A.; Novak, John T.; Chapelle, Francis H.; Benner, Ronald; Kaiser, Karl

2012-01-01

322

Production of activated carbon from a new precursor molasses by activation with sulphuric acid.  

PubMed

Activated carbon has been prepared from molasses, a natural precursor of vegetable origin resulting from the sugar industry in Morocco. The preparation of the activated carbon from the molasses has been carried out by impregnation of the precursor with sulphuric acid, followed by carbonisation at varying conditions (temperature and gas coverage) in order to optimize preparation parameters. The influence of activation conditions was investigated by determination of adsorption capacity of methylene blue and iodine, the BET surface area, and the pore volume of the activated carbon were determined while the micropore volume was determined by the Dubinin-Radushkevich (DR) equation. The activated materials are mainly microporous and reveal the type I isotherm of the Brunauer classification for nitrogen adsorption. The activated carbons properties in this study were found for activation of the mixture (molasses/sulphuric acid) in steam at 750 degrees C. The samples obtained in this condition were highly microporous, with high surface area (> or =1200 m2/g) and the maximum adsorption capacity of methylene blue and iodine were 435 and 1430 mg/g, respectively. PMID:15721553

Legrouri, K; Khouya, E; Ezzine, M; Hannache, H; Denoyel, R; Pallier, R; Naslain, R

2005-02-14

323

Dissolved inorganic carbon concentrations and stable carbon isotope ratios in streams polluted by variable amounts of acid mine drainage  

NASA Astrophysics Data System (ADS)

SummaryDissolved inorganic carbon (DIC) concentrations and stable carbon isotopes of DIC (? 13C DIC) were determined in streams polluted by acid mine drainage (AMD). The aim was to assess the effects of variable AMD contamination on DIC dynamics and ? 13C DIC. The stream with relatively high metal (e.g., Fe, Al, Mn) concentrations exhibited downstream decreases in pH because production of protons by the chemical evolution of AMD exceeded the stream's buffering capacity. DIC dynamics in this stream was driven by proton-enhanced CO 2 degassing. In the stream with lower metal concentrations, the protons were neutralized by HCO3- and pH increased in the downstream direction. In this stream, DIC dynamics was driven by CO 2 loss due to higher partial pressure of CO 2 (pCO 2) in stream water compared to atmospheric. In both contaminated watersheds, CO 2 loss resulted in seasonal exports of <1-47% of stream DIC. The decreases in DIC concentrations were accompanied by a variable enrichment of ? 13C DIC which depended on the extent to which HCO3- was dehydrated to CO 2(aq), how CO 2 was lost from the streams, and if carbon in DIC was exchanged with atmospheric CO 2. The ? 13C DIC was enriched by <3.0‰ when CO 2 loss was proton enhanced and isotopic fractionation was controlled mostly by diffusion. The ? 13C DIC was enriched by >3.0‰ when CO 2 loss was neutralization induced and CO 2 loss was accompanied by partial exchange of carbon between DIC and atmospheric CO 2. We conclude that DIC loss and ? 13C DIC enrichment in AMD-contaminated streams depends on the rate of production and amount of protons produced by metal hydrolysis, the stream's buffering capacity, and the mechanism of CO 2 loss.

Atekwana, Eliot A.; Fonyuy, Ernest W.

2009-06-01

324

An evaluation of waste gypsum-based precipitated calcium carbonate for acid mine drainage neutralization.  

PubMed

Precipitated CaCO(3) compounds recovered from pulped waste gypsum using some carbonate and hydroxide-based reagents were evaluated for their utilization in acid mine drainage (AMD) neutralization. The neutralization potentials, acid neutralization capacities and compositions of the CaCO(3) compounds were determined and compared with some commercial CaCO(3). It was observed that CaCO(3) recovered from waste gypsum using Na(2)CO(3) significantly neutralized AMD compared with commercial CaCO(3) and that recovered using both (NH(4))(2)CO(3) or NH(4)OH-CO(2) reagents. Moreover, a higher acid neutralization capacity of 1,370 kg H(2)SO(4)/t was determined for CaCO(3) recovered from waste gypsum using Na(2)CO(3) compared with an average of 721 and 1,081 kg H(2)SO(4)/t for ammonium-based CaCO(3) and commercial CaCO(3) respectively. The inorganic carbon content for the CaCO(3) recovered using Na(2)CO(3) and ammonium-based reagents of 49 and 34% respectively confirmed their observed neutralization potentials and acid neutralization capacities, while energy dispersive X-ray fluorescence suggested absence of major oxide impurities, with the exception of residual SO(4)(2-) and Na(2)O which still requires further reduction in the respective compounds. PMID:22508119

Zvimba, J N; Mulopo, J; Bologo, L T; Mathye, M

2012-01-01

325

Emissions of organic aerosol mass, black carbon, particle number, and regulated and unregulated gases from scooters and light and heavy duty vehicles with different fuels  

NASA Astrophysics Data System (ADS)

A sampling campaign with seven different types of vehicles was conducted in 2009 at the vehicle test facilities of the Joint Research Centre (JRC) in Ispra (Italy). The vehicles chosen were representative of some categories circulating in Europe and were fueled either with standard gasoline or diesel and some with blends of rapeseed methyl ester biodiesel. The aim of this work was to improve the knowledge about the emission factors of gas phase and particle-associated regulated and unregulated species from vehicle exhaust. Unregulated species such as black carbon (BC), primary organic aerosol (OA) content, particle number (PN), monocyclic and polycyclic aromatic hydrocarbons (PAHs) and a~selection of unregulated gaseous compounds, including nitrous acid (N2O), ammonia (NH3), hydrogen cyanide (HCN), formaldehyde (HCHO), acetaldehyde (CH3CHO), sulfur dioxide (SO2), and methane (CH4), were measured in real time with a suite of instruments including a high-resolution aerosol time-of-flight mass spectrometer, a resonance enhanced multi-photon ionization time-of-flight mass spectrometer, and a high resolution Fourier transform infrared spectrometer. Diesel vehicles, without particle filters, featured the highest values for particle number, followed by gasoline vehicles and scooters. The particles from diesel and gasoline vehicles were mostly made of BC with a low fraction of OA, while the particles from the scooters were mainly composed of OA. Scooters were characterized by super high emissions factors for OA, which were orders of magnitude higher than for the other vehicles. The heavy duty diesel vehicle (HDDV) featured the highest nitrogen oxides (NOx) emissions, while the scooters had the highest emissions for total hydrocarbons and aromatic compounds due to the unburned and partially burned gasoline and lubricant oil mixture. Generally, vehicles fuelled with biodiesel blends showed lower emission factors of OA and total aromatics than those from the standard fuels. The scooters were the main emitters of aromatic compounds, followed by the gasoline vehicle, the diesel vehicles and the HDDV.

Chirico, R.; Clairotte, M.; Adam, T. W.; Giechaskiel, B.; Heringa, M. F.; Elsasser, M.; Martini, G.; Manfredi, U.; Streibel, T.; Sklorz, M.; Zimmermann, R.; DeCarlo, P. F.; Astorga, C.; Baltensperger, U.; Prevot, A. S. H.

2014-06-01

326

A new method for sampling fumarolic gases: Analysis of major, minor and metallic trace elements with ammonia solutions  

NASA Astrophysics Data System (ADS)

A new method using ammonia solutions in pre-evacuated quartz bottles has been experimented for volcanic gas sampling and analysing. Various tests (reproducibility, variability and comparison with known methods such as NaOH pre-evacuated bottles and acid condensates) have been performed to check for their efficiency. By using ammonia solutions, acid gases (St, HCl, HF), carbon dioxide, noncondensible gases (N 2, Ar, …) and metallic trace elements (MTE) can be measured with standard methods (HPLC, GC, titrimetry, ICP-MS). Results show that acid gases, CO 2 and noncondensible gases are sampled and analysed with similar efficiency in NH 4OH bottles than by using the known and accurate NaOH method. Moreover, a key point is that NH 4OH solutions, after undergoing adequate processing (oxidation and acidification) allow also precise MTE measurements by using standard ICP-MS methods. Such MTE measurements appear much more reliable than those performed on acid condensates. Pre-evacuated ammonia bottles appear therefore as an optimum tool to collect volcanic gases and to obtain their complete chemical composition.

Sortino, F.; Nonell, A.; Toutain, J. P.; Munoz, M.; Valladon, M.; Volpicelli, G.

2006-11-01

327

Habit modification of calcium carbonate in the presence of malic acid  

NASA Astrophysics Data System (ADS)

The ability of malic acid to control calcium carbonate morphology has been investigated by aging calcium chloride solution in the presence of urea in a 90 °C bath. Malic acid favors the formation of calcite. A transition from single block to aggregate with special morphology occurs upon increasing malic acid concentration. The morphological development of CaCO 3 crystal obviously depends on the starting pH. CaCO 3 crystal grows from spindle seed to dumbbell in the pH regime from 7 to 11; while it evolves from spindle seed, through peanut, to sphere at pH=11.5. Both dumbbell and sphere consist of rods that are elongated along c-axis and capped with three smooth, well-defined rhombic {1 0 4} faces. A tentative growth mechanism is proposed based on the fractal model suggested by R. Kniep and S. Busch [Angew. Chem. Int. Ed. Engl. 35 (1996) 2624].

Mao, Zhaofeng; Huang, Jianhua

2007-02-01

328

The relationship between blood carbon dioxide, acid-base balance and calcium metabolism in the hyperthermic laying hen  

E-print Network

THE RELATIONSHIP BETWEEN BLOOD CARBON DIOXIDE, ACID-BASE BALANCE AND CALCIUM METABOLISM IN THE HYPERTHERMIC LAYING HEN A Thesis by YOSHITAKA ONO Subrnittcd to thc Office of Graduate Studies of Texas AA, M University in partial I...'ulfillmcnt of thc requirements for thc dcgrcc of MASTER OF SCIENCE Dcccmbcr 1988 Major Sulajccu Poultry Scicncc THE RELATIONSHIP BETWEEN BLOOD CARBON DIOXIDE, ACID-BASE BALANCE AND CALCIUM METABOLISM IN THE HYPERTHERMIC LAYING HEN A Thesis by YOSHITAKA ONO...

Ono, Yoshitaka

2012-06-07

329

Capacity of activated carbon in the removal of acid brilliant blue: Determination of equilibrium and kinetic model parameters  

Microsoft Academic Search

The adsorption of acid brilliant blue onto thermally activated coir pith carbon in aqueous solution was studied in a batch system with respect to contact time, pH, and temperature. Acidic pH was favorable for the adsorption of this dye. The surface characterization of thermally activated coir pith carbon was performed using the FT-IR technique. Kinetic studies showed that the adsorption

D. Kavitha; C. Namasivayam

2008-01-01

330

Effect of carbon foams as negative current collectors on partial-state-of-charge performance of lead acid batteries  

Microsoft Academic Search

Flooded lead acid batteries were assembled by using a pitch-based carbon foam and a punched lead sheet as the negative current collectors, respectively. Comparative galvanostatic charge–discharge experiments were performed on the batteries to evaluate the effect of the carbon foam as a negative current collector material on the performance of lead acid batteries under partial-state-of-charge operation. The results indicate that

Ya Chen; Bai-Zhen Chen; Li-Wen Ma; Yan Yuan

2008-01-01

331

Modeling of dissolution patterns for carbonate acidizing in the porous media  

NASA Astrophysics Data System (ADS)

Matrix acidizing is a common technique to stimulate wells for improving well inflow performance. In this treatment that is widely used in the oil industry, acid solution is injected into the formation to dissolve some minerals to increase permeability of carbonate near the wellbore. The aim of the treatment is to create empty channels called wormholes. Wormholing in carbonate rocks is a complex 3-D phenomenon. Matrix acidizing generally should be applied when a well has a high skin factor that cannot be attributed to partial penetration, perforation efficiency or other mechanical aspects of the completion. Obviously, it is of extreme importance to quantify the skin factor to evaluate the effectiveness of stimulation treatments. When wormholes extend beyond the damaged zone or connect with natural fissures in the formation, a negative skin effect is obtained. An ideal matrix treatment restores the permeability in the near wellbore region to a value at least as high as the original undamaged permeability; it accomplishes this over the entire completed interval and it leaves the formation in the treated region with high relative permeability to the oil and/or gas phase. Designing a treatment should strive to achieve this ideal at the lowest possible cost, which requires consideration of the many physical and chemical interactions taking place between the injected fluids and the reservoir minerals and fluids. In this work, a threescale continuum model is used to model reactive dissolution of carbonate rocks in radial flow. Both the Darcy and pore scale physics such as mass transfer of acid molecules to the mineral surface and subsequent reaction at the surface, changing pore structure and variations in reservoir permeability are included in this model. Partial differential equations obtained from the model, have been solved by numerical method. The influence of reservoir temperature on optimum injection rate is investigated. Results show that optimum injection rate increases with temperature.

Samadi, Fereshteh; Esmaeilzadeh, Feridun; Mowla, Dariush

2012-05-01

332

[Effects of carbon and nitrogen sources on 5-keto-gluconic acid production].  

PubMed

Gluconobacter oxydans is known to oxidize glucose to gluconic acid (GA), and subsequently, to 2-keto-gluconic acid (2KGA) and 5-keto-gluconic acid (5KGA), while 5KGA can be converted to L-(+)-tartaric acid. In order to increase the production of 5KGA, Gluconobacter oxydans HGI-1 that converts GA to 5KGA exclusively was chosen in this study, and effects of carbon sources (lactose, maltose, sucrose, amylum and glucose) and nitrogen sources (yeast extract, fish meal, corn steep liquor, soybean meal and cotton-seed meal) on 5KGA production were investigated. Results of experiment in 500 mL shake-flask show that the highest yield of 5KGA (98.20 g/L) was obtained using 100 g/L glucose as carbon source. 5KGA reached 100.20 g/L, 109.10 g/L, 99.83 g/L with yeast extract, fish meal and corn steep liquor as nitrogen source respectively, among which the optimal nitrogen source was fish meal. The yield of 5KGA by corn steep liquor is slightly lower than that by yeast extract. For the economic reason, corn steep liquor was selected as nitrogen source and scaled up to 5 L stirred-tank fermentor, and the final concentration of 5KGA reached 93.80 g/L, with its maximum volumetric productivity of 3.48 g/(L x h) and average volumetric productivity of 1.56 g/(L x h). The result obtained in this study showed that carbon and nitrogen sourses for large-scale production of 5KGA by Gluconobacter oxydans HGI-1 were glucose and corn steep liquor, respectively, and the available glucose almost completely (85.93%) into 5KGA. PMID:24818481

Tan, Zhilei; Wang, Hongcui; Wei, Yuqiao; Li, Yanyan; Zhong, Cheng; Jia, Shiru

2014-01-01

333

40 CFR 60.263 - Standard for carbon monoxide.  

Code of Federal Regulations, 2012 CFR

...electric submerged arc furnace any gases which contain, on a dry basis...carbon monoxide. Combustion of such gases under conditions acceptable to...include, but are not limited to, flaring of gases or use of gases as fuel for...

2012-07-01

334

40 CFR 60.263 - Standard for carbon monoxide.  

Code of Federal Regulations, 2011 CFR

...electric submerged arc furnace any gases which contain, on a dry basis...carbon monoxide. Combustion of such gases under conditions acceptable to...include, but are not limited to, flaring of gases or use of gases as fuel for...

2011-07-01

335

40 CFR 60.263 - Standard for carbon monoxide.  

Code of Federal Regulations, 2013 CFR

...electric submerged arc furnace any gases which contain, on a dry basis...carbon monoxide. Combustion of such gases under conditions acceptable to...include, but are not limited to, flaring of gases or use of gases as fuel for...

2013-07-01

336

Simultaneous Determination of Dopamine, Serotonin and Ascorbic Acid at a Glassy Carbon Electrode Modified with Carbon-Spheres  

PubMed Central

A novel glassy carbon electrode (GCE) modified with carbon-spheres has been fabricated through a simple casting procedure. The modified GCE displays high selectivity and excellent electrochemical catalytic activities towards dopamine (DA), serotonin (5-HT), and ascorbic acid (AA). In the co-existence system, the peak separations between AA and DA, DA and 5-HT, and AA and 5-HT are large up to 230, 180, and 410 mV, respectively. Differential pulse voltammetry (DPV) has been employed to simultaneously detect DA, 5-HT, and AA, and the linear calibration curves for DA, 5-HT, and AA are obtained in the range of 20.0–150.0 ?M, 40.0–750.0 ?M and 300.0–2,000.0 ?M with detection limits (S/N = 3) of 2.0 ?M, 0.7 ?M and 0.6 ?M, respectively. The proposed electrode has been applied to detect DA, 5-HT, and AA in real samples using standard addition method with satisfactory results. PMID:24135993

Zhou, Jianqing; Sheng, Meili; Jiang, Xueyue; Wu, Guozhi; Gao, Feng

2013-01-01

337

Controls on the microbial utilization of carbon monoxide and formic acid in Acidic Hydrothermal Springs in Yellowstone National Park  

NASA Astrophysics Data System (ADS)

In hydrothermal systems, dissolved carbon dioxide (CO2) in the presence of reduced iron-bearing minerals, such as those found in basalt, can be reduced to form formic acid (HCOOH). HCOOH can then be dehydrated in a side reaction, resulting in the generation of carbon monoxide (CO), which forms an equilibrium with HCOOH. HCOOH can also be further reduced to methane, and longer chain hydrocarbons. Geochemical measurements have demonstrated the presence of elevated concentrations of HCOOH, dissolved CO, and dissolved inorganic carbon (CO2, H2CO3), in high temperature, low pH springs in Yellowstone National Park (YNP). Likewise, a number of compounds that could potentially serve as electron acceptors (e.g. S0, SO42-, NO3-, Fe3+) in the oxidation of CO or formic acid have been detected in many of these systems. We hypothesized that the utilization of CO and HCOOH as carbon and/or energy sources is a broadly-distributed metabolic strategy in high temperature, low pH springs in YNP. To test this hypothesis, radiolabeled CO (14CO) and HCOOH (H14COOH) were used to determine rates of CO and formate oxidation activity in three hot springs in YNP ranging in temperature from 53 °C to 89 °C and pH from 2.5 to 5.3. In parallel, 16S rRNA gene sequencing and enrichment isolation techniques were employed to identify the microorganisms responsible for these activities. Our results indicate that CO and HCOOH are important sources of carbon and/or energy in high temperature, low pH hydrothermal springs in Yellowstone National Park. Rates of CO oxidation appear to be orders of magnitude lower than those of HCOOH oxidation. One possible explanation for this result is that HCOOH is preferentially utilized, consistent with thermodynamic calculations indicating that HCOOH liberates approximately 215 kJ/mol more Gibbs energy (under standard conditions) than CO when oxidized with oxygen (O2) as the electron acceptor. Redox couples of HCOOH oxidation with other electron acceptors (e.g. SO4 or S0) also yield more energy than those of CO oxidation with the same electron acceptors. Pyrotag sequencing of 16S rRNA genes from several of these environments reveal the presence of numerically dominant bacteria and archaea that are closely-affiliated with the sulfate respiring genus Thermodesulfobium and the elemental sulfur respiring genus Acidilobus, respectively. The genome sequence of a closely related strain of Thermodesulfobium (Thermodesulfobium narugense DSM 14796, 98% identity) indicates that it harbors the genetic potential to oxidize CO and HCOOH, and the genome of the sulfur-respiring Acidilobus sulfurireducens str. 18D70 (96% identity) indicates the presence of the genetic potential to oxidize HCOOH. Active sulfide production in enrichments with CO and formate as sole carbon and energy sources with elemental sulfur or sulfate as electron acceptor suggests coupling between these substrates. Collectively, these data are suggestive of preferential utilization of substrates that reflect the energetics of their oxidation, with metabolic coupling of HCOOH and CO oxidation with sulfur and sulfate, respectively.

Urschel, M.; Kubo, M. W.; Hoehler, T. M.; Boyd, E. S.; Peters, J.

2012-12-01

338

HELSINKI UNIVERSITY OF TECHNOLOGY ENE-47.153 Greenhouse gases andGreenhouse gases and  

E-print Network

% Mobile combustion sources ~ 14 % Nitric acid production ~ 5 % HFCs, PFCs, SF66 Substution of ozone - 11700 Sulphur hexafluoride, SF66 23900 - depleting gases ~ 36 % HCFC-22 production ~ 27 % Electrical transmission and production ~ 17 % HELSINKI

Zevenhoven, Ron

339

Karstification without carbonic acid: Bedrock dissolution by gypsum-driven dedolomitization  

NASA Astrophysics Data System (ADS)

Aggressive karstification can take place where dolomite and gypsum are in contact with the same aquifer. Gypsum dissolution drives the precipitation of calcite, thus consuming carbonate ions released by dolomite. Lake Banyoles, in northeastern Spain, is a karst lake supplied by sublacustrine springs, and karstic collapse is occurring in the immediate vicinity of the lake. Lake water is dominated by Mg-Ca and SO4-HCO3, and is supersaturated with calcite that is actively accumulating in lake sediments. Water chemistry, sulfur isotope composition, local stratigraphy, and mass-balance modelling suggest that the primary karst-forming process at at Lake Banyoles is dedolomitization of basement rocks driven by gypsum dissolution. Karstification takes place along the subsurface contact between the gypsiferous Beuda Formation and the dolomitic Perafita Formation. This process is here recognized for the first time to cause karstification on a large scale; this is significant because it proceeds without the addition of soil-generated carbonic acid. Gypsum-driven dedolomitization may be responsible for other karstic systems heretofore attributed to soil-generated carbonic acid.

Bischoff, James L.; Juliá, Ramon; Shanks, Wayne C., III; Rosenbauer, Robert J.

1994-11-01

340

CORROSION TESTING OF CARBON STEEL IN OXALIC ACID CHEMICAL CLEANING SOLUTIONS  

SciTech Connect

Radioactive liquid waste has been stored in underground carbon steel tanks for nearly 60 years at the Savannah River Site. The site is currently in the process of removing the waste from these tanks in order to place it into vitrified, stable state for longer term storage. The last stage in the removal sequence is a chemical cleaning step that breaks up and dissolves metal oxide solids that cannot be easily pumped out of the tank. Oxalic acid has been selected for this purpose because it is an effective chelating agent for the solids and is not as corrosive as other acids. Electrochemical and immersion studies were conducted to investigate the corrosion behavior of carbon steel in simulated chemical cleaning environments. The effects of temperature, agitation, and the presence of sludge solids in the oxalic acid on the corrosion rate and the likelihood of hydrogen evolution were determined. The testing showed that the corrosion rates decreased significantly in the presence of the sludge solids. Corrosion rates increased with agitation, however, the changes were less noticeable.

Wiersma, B.; Mickalonis, J.; Subramanian, K.; Ketusky, E.

2011-10-14

341

First-principles Study of Physisorption of Nucleic Acid Bases on Small-Diameter Carbon Nanotube  

E-print Network

We report the results of our first-principles study based on density functional theory on the interaction of the nucleic acid base molecules adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U), with a single-walled carbon nanotube (CNT). Specifically, the focus is on the physisorption of base molecules on the outer wall of a (5,0) metallic CNT possessing one of the smallest diameters possible. Compared to CNTs with large diameters, the physisorption energy is found to be reduced in the high-curvature case. The base molecules exhibit significantly different interaction strengths, and the calculated binding energies follow the hierarchy G > A > T > C > U, which appears to be independent of the tube curvature. The stabilizing factor in the interaction between the base molecule and CNT is dominated by the molecular polarizability that allows a weakly attractive dispersion force to be induced between them. The present study provides an improved understanding of the role of the base sequence in deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) on their interactions with carbon nanotubes of varying diameters.

S. Gowtham; Ralph H. Scheicher; Ravindra Pandey; Shashi P. Karna; Rajeev Ahuja

2007-09-14

342

Long-term carbon stabilization through sorption of dissolved aromatic acids to reactive particles (Invited)  

NASA Astrophysics Data System (ADS)

Short-range order minerals are highly reactive soil constituents that are found in all soils and in particularly high quantities in volcanic soils. They retain large quantities of soil carbon, thereby acting as a long-term sink for carbon dioxide, but the main source for this carbon accumulation in soil is not yet known. We evaluated the biochemistry of solid and dissolved organic carbon in horizons containing differing short-range ordered mineral concentrations using solid-state 13C nuclear magnetic resonance spectroscopy, stable isotope measurements and soil column leaching experiments across a well-constrained chronosequence of volcanic soils in Hawai’i. Molecular mixing model results, isotopic and elemental measurements, indicate that the oldest and most persistent C stores across the chronosequence are comprised not of highly microbially processed organic matter (e.g. proteins or lipids), but rather of partially oxidized aromatic plant compounds (up to 62% of the total soil C) preserved through chemical bonding to reactive soil minerals via carboxyl-rich functionalities. NMR spectra obtained from deep soil horizons containing an abundance of SRO minerals, showed strong chemical resemblance to that of DOM derived from plant litter. Solublization and high production rates of recalcitrant DOM controlled substantially by microbial activity were observed in the soil column leaching experiments. When the DOM-rich solution derived from organic horizons was leached through mineral soil horizons, the quantity of DOM sorbed was dependent on the abundance of SRO minerals present in the soil. These results suggest that microbial-driven DOM formation derived from plant litter and the subsequent binding of the aromatic acids in the DOM to reactive mineral surfaces is a dominant source for long-term soil carbon stabilization in these soils. This potentially globally significant carbon sink may be unresponsive to climate change over decadal to centennial timescales due to strong particle sorption via carboxyl-rich functionalities.

Kramer, M. G.; Sanderman, J.; Chadwick, O.; Chorover, J.; Vitousek, P.

2010-12-01

343

Acetic-acid-catalyzed and subcritically dried carbon aerogels with a nanometer-sized structure and a wide density range  

Microsoft Academic Search

Organic acids used as catalysts allow for the preparation of resorcinol–formaldehyde (RF) and carbon aerogels without any metallic impurities. In this paper we present RF aerogels originating from an aqueous gelation and subcritical drying after the exchange of the pore water against acetone. In contrast to earlier attempts, very high catalyst concentrations of the weak acetic acid were used. The

R. Brandt; J. Fricke

2004-01-01

344

Synthesis of biodiesel from a model waste oil feedstock using a carbon-based solid acid catalyst: Reaction and separation  

Microsoft Academic Search

A solid acid catalyst that can keep high activity and stability is necessary when low cost feedstocks are utilized for biodiesel synthesis because the reaction medium contains a large amount of water. Three solid acid catalysts were prepared by the sulfonation of carbonized vegetable oil asphalt and petroleum asphalt. The structure of these catalysts was characterized by a variety of

Qing Shu; Zeeshan Nawaz; Jixian Gao; Yuhui Liao; Qiang Zhang; Dezheng Wang; Jinfu Wang

2010-01-01

345

An electrochemical biosensor for ascorbic acid based on carbon-supported PdNi nanoparticles.  

PubMed

Carbon-supported PdNi nanoparticles (PdNi/C) were synthesized using a novel synthetic route, and characterized by transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The overall metallic content (Pd+Ni) was 10% (w/w) and uniformly distributed in the carbon black (90%) matrix. The electrocatalytic performance of the PdNi/C modified glassy carbon electrode (GCE) was investigated for ascorbic acid (AA) oxidation, and showed better catalytic activity than an equal amount of commercially available palladium carbon catalyst. The oxidation potential of AA was negatively shifted to -0.05 V. The biosensor tolerated a wide linear concentration range for AA, from 1.0×10(-5)M to 1.8×10(-3)M (R=0.9973), with a detection limit of 0.5 ?M (S/N=3). Our results demonstrate that PdNi/C nanomaterials have excellent AA sensing capability, including a fast response time, high reproducibility and stability, with great promise in the quantification of AA in real samples. These qualities make the Pd-based bimetallic catalysts promising candidates for amperometric sensing. PMID:23428731

Zhang, Xin; Cao, Yang; Yu, Sha; Yang, Fengchun; Xi, Pinxian

2013-06-15

346

Process for the manufacture of carbon or graphite fibers  

NASA Technical Reports Server (NTRS)

Carbon or graphite fibers are manufactured by heating polyacrylonitrile fiber materials in various solutions and gases. They are characterized in that the materials are heated to temperatures from 150 to 300 C in a solution containing one or more acids from the group of carbonic acids, sulfonic acids, and/or phenols. The original molecular orientation of the fibers is preserved by the cyclization that occurs before interlacing, which gives very strong and stiff carbon or graphite fibers without additional high temperature stretching treatments.

Overhoff, D.; Winkler, E.; Mueller, D.

1979-01-01

347

Evidence for effecting a lag in carbon dioxide hydration in the sea by carbamino carboxylic acid complexes  

E-print Network

; such mixtures have the ability to resist changes in pH upon addition of small amounts of strong acids or bases or upon appreciable dilution ('Aillard, et al, 1956). The buffer salts in sea water are those of carbonic and boric acids. Dittmar's values of 0.... 14 and 0. 026 gm/kg for bicarbonate ion and boric acid content respec- tively when the chlorinity of the sea water is 19 5 (Lyman and Fleming, 1940), show that the buffer mechan- ism of sea water is primarily concerned with the carbon dioxide...

Smith, James Benjamin

2012-06-07

348

The interaction of acid mine drainage with a carbonate terrane: evidence from the Obey River, north-central Tennessee  

NASA Astrophysics Data System (ADS)

The production of acidic drainage from active or abandoned coal mines is controlled by a complex series of reactions triggered by the oxidation of sulphide minerals. Limestone is frequently used as a neutralizing agent; neutralization occurs both through dissolution of the limestone and exsolution of carbon dioxide from the water. Demonstration of these processes in a natural system is provided by the East Fork of the Obey River, where acidic mine waters travel through conduits in limestone bedrock for several kilometers. Application of discharge-concentration relationships allows tracking of the evolution of these waters within the karst aquifer. Several trends are evident. Virtually all of the iron in the acid mine drainage is precipitated along the flow path within the limestone; the H + released during this reaction, together with the H + generated by pyrite oxidation, is largely neutralized by both exsolution of CO 2 and dissolution of calcite/dolomite in the carbonate bedrock (releasing calcium and magnesium). Nevertheless, the pH is still sufficiently low that all bicarbonate is converted to carbonic acid. Leaching of clay minerals by the acid waters releases small amounts of Al and Si; the species Cl -, F - and NO -3 are more or less inert. The sulphate concentration substantially increases during evolution of the acid drainage; this seems to be related to an input of sulphate-enriched waters that have dissolved gypsum/anhydrite as they follow deep flow paths within the limestone. Calculations of the relative proportions of H + removed by reaction with calcite/dolomite and CO 2 degassing show that the latter is important in acidic waters that have reacted significantly with limestone and can readily lose CO 2 to the atmosphere. These results indicate that acid neutralization through carbonic acid dissociation, in addition to neutralization through dissolution of carbonates, is a useful method for the commercial a batement of acid mine drainage.

Webb, John A.; Sasowsky, Ira D.

1994-09-01

349

Greenhouse Gases: The Overlooked Sources  

NSDL National Science Digital Library

This radio broadcast, which took place during the Kyoto Conference on global warming, discusses well-known and more obscure sources of greenhouse gases. Solutions to reduce carbon emissions are discussed, including creating fuel with less carbon in it (biomass fuels); reducing driving by increasing the cost of fuel; and improving vehicle fuel economy. The broadcast then introduces the topic of methane as a greenhouse gas; although less is emitted, it is about fifty times more effective than carbon dioxide at warming the planet. Cattle are a major source of methane; some ideas are introduced for monitoring and reducing their emissions. There is also discussion of whether global warming could be a result of natural variability as opposed to the result of a human-caused greenhouse effect. The broadcast is 49 minutes and 39 seconds in length.

350

Gases in Seawater  

NASA Astrophysics Data System (ADS)

The annual gross and net primary productivity of the surface oceans is similar in size to that on land (IPCC, 2001). Marine productivity drives the cycling of gases such as oxygen (O2), dimethyl sulfide (DMS), carbon monoxide (CO), carbon dioxide (CO2), and methyl iodide (CH3I) which are of fundamental importance in studies of marine productivity, biogeochemical cycles, atmospheric chemistry, climate, and human health, respectively. For example, ˜30% of the world's population (1,570 million) is thought to be at risk of iodine-deficiency disorders that impair mental development (WHO, 1996). The main source of iodine to land is the supply of volatile iodine compounds produced in the ocean and then transferred to the atmosphere via the air-surface interface. The flux of these marine iodine species to the atmosphere is also thought to be important in the oxidation capacity of the troposphere by the production of the iodine oxide radical ( Alicke et al., 1999). A further example is that the net flux of CO2 from the atmosphere to the ocean, ˜1.7±0.5 Gt C yr-1, represents ˜30% of the annual release of anthropogenic CO2 to the atmosphere (IPCC, 2001). This net flux is superimposed on a huge annual flux (90 Gt C yr-1) of CO2 that is cycled "naturally" between the ocean and the atmosphere. The long-term sink for anthropogenic CO2 is recognized as transfer to the ocean from the atmosphere. A final example is the emission of volatile sulfur, in the form of DMS, from the oceans. Not only is an oceanic flux from the oceans needed to balance the loss of sulfur (a bioessential element) from the land via weathering, it has also been proposed as having a major control on climate due to the formation of cloud condensation nuclei (Charlson et al., 1987). Indeed, the existence of DMS and CH3I has been used as evidence in support of the Gaia hypothesis (Lovelock, 1979).There are at least four main processes that affect the concentration of gases in the water column: biological production and consumption, photochemistry, air-sea exchange, and vertical mixing. We will not discuss the effect of vertical mixing on gases in seawater and instead refer the reader to Chapter 6.08. Nor will we consider the deeper oceans as this region is discussed in chapters on benthic fluxes and early diagenesis (Chapter 6.11), the biological pump (Chapter 6.04), and the oceanic calcium carbonate cycle (Chapter 6.19) all in this volume. We will discuss the cycling of gases in surface oceans, including the thermocline, and in particular concentrate on the exchange of various volatile compounds across the air-sea interface.As we will show, while much is known about the cycling of gases such as CO2 and DMS in the water column, frustratingly little is known about many of the chemical species for which the ocean is believed to be a significant source to the atmosphere. We suspect the passage of time will reveal that the cycling of volatile compounds containing selenium and iodine may well prove as complex as that of DMS. Early studies of DMS assumed that it was produced from a precursor compound, dimethylsulfoniopropionate (DMSP), known to be present in some species of phytoplankton, and that the main sink in the water column was exchange across the air-sea interface. We now know that DMSP and DMS are both rapidly cycled in water column by a complex interaction between phytoplankton, microzooplankton, bacteria, and viruses (see Figure 1). Some detailed process experiments have revealed that only ˜10% of the total DMS produced (and less than 1.3% of the DMSP produced) is transferred to the atmosphere, with the bulk of the DMS and DMSP, either being recycled in the water column or photo-oxidized (Archer et al., 2002b).

Nightingale, P. D.; Liss, P. S.

2003-12-01

351

Distribution of Hydrogen Peroxide, Carbon Dioxide, and Sulfuric Acid in Europa's Icy Crust  

NASA Technical Reports Server (NTRS)

Galileo's Near Infrared Mapping Spectrometer (NIMS) detected hydrogen peroxide, carbon dioxide and a hydrated material on Europa's surface, the latter interpreted as hydrated sulfuric acid (H2SO4*nH2O) or hydrated salts. Related compounds are molecular oxygen, sulfur dioxide, and two chromophores, one that is dark in the ultraviolet(UV) and concentrated on the trailing side, the other brighter in the UV and preferentially distributed in the leading hemisphere. The UV-dark material has been suggested to be sulfur.

Carlson, R. W.

2004-01-01

352

Dissociation constants of carbonic acid in seawater as a function of salinity and temperature  

Microsoft Academic Search

Potentiometric measurements of the stoichiometric constants on the seawater pH scale for the dissociation of carbonic acid in seawater (K1?=[H+][HCO3?]\\/[CO2] and K2?=[H+][CO32?]\\/[HCO3?]) have been made as a function of salinity (1 to 50) and temperature (0 to 50 °C). The results have been fitted to the equations (T\\/K)pKi?pKi0=Ai+Bi\\/T+Ciln?T.The values of pKi0 in pure water are taken from the early work

Frank J. Millero; Taylor B. Graham; Fen Huang; Héctor Bustos-Serrano; Denis Pierrot

2006-01-01

353

Electrocatalytic oxidation of some amino acids on a nickel–curcumin complex modified glassy carbon electrode  

Microsoft Academic Search

This study investigated the electrocatalytic oxidation of alanine, l-arginine, l-phenylalanine, l-lysine and glycine on poly-Ni(II)–curcumin film (curcumin: 1,7-bis [4-hydroxy-3-methoxy phenyl]-1,6-heptadiene-3,5-dione) electrodeposited on a glassy carbon electrode in alkaline solution. The process of oxidation and its kinetics were established by using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy techniques. Voltammetric studies indicated that in the presence of amino acids the anodic

S. Majdi; A. Jabbari; H. Heli; A. A. Moosavi-Movahedi

2007-01-01

354

ELECTROCHEMICAL STUDIES ON THE CORROSION OF CARBON STEEL IN OXALIC ACID CLEANING SOLUTIONS  

SciTech Connect

The Savannah River Site (SRS) will disperse or dissolve precipitated metal oxides as part of radioactive waste tank closure operations. Previously SRS has utilized oxalic acid to accomplish this task. Since the waste tanks are constructed of carbon steel, a significant amount of corrosion may occur. Although the total amount of corrosion may be insignificant for a short contact time, a significant amount of hydrogen may be generated due to the corrosion reaction. Linear polarization resistance and anodic/cathodic polarization tests were performed to investigate the corrosion behavior during the process. The effect of process variables such as temperature, agitation, aeration, sample orientation, light as well as surface finish on the corrosion behavior were evaluated. The results of the tests provided insight into the corrosion mechanism for the iron-oxalic acid system.

Wiersma, B; John Mickalonis, J

2007-10-08

355

Preparation and characterization of aligned carbon nanotubes/polylactic acid composite fibers  

NASA Astrophysics Data System (ADS)

Aligned functionalized multiwalled carbon nanotubes/polylactic acid (MWNTs-PCL/PLA) composite fibers were successfully prepared by electrospinning processing. The MWNTs bonded with the polycaprolactone chains exhibited excellent uniform dispersion in PLA solution by comparing with the acid-functionalized MWNTs and amino-functionalized MWNTs. Optical microscopy was used to study the aligned degree of the fibers and to investigate the influences of the electrodes distance on the alignment and structure of the fibers, and results showed that the best quality of aligned fibers with dense structure and high aligned degree were obtained at an electrodes distance of 3 cm. Moreover, the MWNTs embedded inside the MWNTs-PCL/PLA fibers displayed well orientation along the axes of the fibers, which was demonstrated by field emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy.

Kong, Yuxia; Yuan, Jie; Qiu, Jun

2012-07-01

356

Carbon nanofiber supported bimetallic PdAu nanoparticles for formic acid electrooxidation  

NASA Astrophysics Data System (ADS)

Carbon nanofiber (CNF) supported PdAu nanoparticles are synthesized with sodium citrate as the stabilizing agent and sodium borohydride as the reducing agent. High resolution transmission electron microscopy (HRTEM) characterization indicates that the synthesized PdAu particles are well dispersed on the CNF surface and X-ray diffraction (XRD) characterization indicates that the alloying degree of the synthesized PdAu nanoparticles can be improved by adding tetrahydrofuran to the synthesis solution. The results of electrochemical characterization indicate that the addition of Au can promote the electrocatalytic activity of Pd/C catalyst for formic acid oxidation and the CNF supported high-alloying PdAu catalyst possesses better electrocatalytic activity and stability for formic acid oxidation than either the CNF supported low-alloying PdAu catalyst or the CNF supported Pd catalyst.

Qin, Yuan-Hang; Jiang, Yue; Niu, Dong-Fang; Zhang, Xin-Sheng; Zhou, Xing-Gui; Niu, Li; Yuan, Wei-Kang

2012-10-01

357

Studies on a lead-acid cell with electrodeposited lead and lead dioxide electrodes on carbon  

NASA Astrophysics Data System (ADS)

Performance characteristics of a lead-acid cell with electrodeposited lead and lead dioxide electrodes on carbon are evaluated in aqueous sulfuric acid at concentrations ranging from 1 to 4 M. The discharge capacity is practically independent of the discharge rate within the current range studied (˜1 to 15 mA cm -2). The capacity increases with cycling, possibly due to slow attainment of a 'spongy' character for the negative electrode active mass. The capacity also increases with the amount of deposition, reaching a more or less limiting value beyond an optimum deposition. Steady-state discharge behavior, represented by a voltage plateau, shows a nearly Nernstian response, which indicates that the basic electron-transfer processes are quite fast. Experiments involving less than full charge-discharge cycles showed the charging efficiency to pass through a maximum with charging current.

Das, Kaushik; Mondal, Aparesh

358

Water-soluble organic carbon, dicarboxylic acids, ketoacids, and ?-dicarbonyls in the tropical Indian aerosols  

NASA Astrophysics Data System (ADS)

Tropical aerosol (PM10) samples (n = 49) collected from southeast coast of India were studied for water-soluble dicarboxylic acids (C2-C12), ketocarboxylic acids (C2-C9), and ?-dicarbonyls (glyoxal and methylglyoxal), together with analyses of total carbon (TC) and water-soluble organic carbon (WSOC). Their distributions were characterized by a predominance of oxalic acid followed by terephthalic (t-Ph), malonic, and succinic acids. Total concentrations of diacids (227-1030 ng m-3), ketoacids (16-105 ng m-3), and dicarbonyls (4-23 ng m-3) are comparative to those from other Asian megacities such as Tokyo and Hong Kong. t-Ph acid was found as the second most abundant diacid in the Chennai aerosols. This feature has not been reported previously in atmospheric aerosols. t-Ph acid is most likely derived from the field burning of plastics. Water-soluble diacids were found to contribute 0.4%-3% of TC and 4%-11% of WSOC. Based on molecular distributions and backward air mass trajectories, we found that diacids and related compounds in coastal South Indian aerosols are influenced by South Asian and Indian Ocean monsoons. Organic aerosols are also suggested to be significantly transported long distances from North India and the Middle East in early winter and from Southeast Asia in late winter, but some originate from photochemical reactions over the Bay of Bengal. In contrast, the Arabian Sea, Indian Ocean, and South Indian continent are suggested as major source regions in summer. We also found daytime maxima of most diacids, except for C9 and t-Ph acids, which showed nighttime maxima in summer. Emissions from marine and terrestrial plants, combined with land/sea breezes and in situ photochemical oxidation, are suggested especially in summer as an important factor that controls the composition of water-soluble organic aerosols over the southeast coast of India. Regional emissions from anthropogenic sources are also important in megacity Chennai, but their influence is weakened due to the dispersion caused by dynamic land/sea breeze on the coast.

Pavuluri, Chandra Mouli; Kawamura, Kimitaka; Swaminathan, T.

2010-06-01

359

Facile synthesis of boronic acid-functionalized magnetic carbon nanotubes for highly specific enrichment of glycopeptides  

NASA Astrophysics Data System (ADS)

A stepwise strategy was developed to synthesize boronic acid functionalized magnetic carbon nanotubes (MCNTs) for highly specific enrichment of glycopeptides. The MCNTs were synthesized by a solvothermal reaction of Fe3+ loaded on the acid-treated CNTs and modified with 1-pyrenebutanoic acid N-hydroxysuccinimidyl ester (PASE) to bind aminophenylboronic acid (APBA) via an amide reaction. The introduction of PASE could bridge the MCNT and APBA, suppress the nonspecific adsorption and reduce the steric hindrance among the bound molecules. Due to the excellent structure of the MCNTs, the functionalization of PASE and then APBA on MCNTs was quite simple, specific and effective. The glycopeptides enrichment and separation with a magnetic field could be achieved by their reversible covalent binding with the boronic group of APBA-MCNTs. The exceptionally large specific surface area and the high density of boronic acid groups of APBA-MCNTs resulted in rapid and highly efficient enrichment of glycopeptides, even in the presence of large amounts of interfering nonglycopeptides. The functional MCNTs possessed high selectivity for enrichment of 21 glycopeptides from the digest of horseradish peroxidase demonstrated by MALDI-TOF mass spectrometric analysis showing more glycopeptides detected than the usual 9 glycopeptides with commercially available APBA-agarose. The proposed system showed better specificity for glycopeptides even in the presence of non-glycopeptides with 50 times higher concentration. The boronic acid functionalized MCNTs provide a promising selective enrichment platform for precise glycoproteomic analysis.A stepwise strategy was developed to synthesize boronic acid functionalized magnetic carbon nanotubes (MCNTs) for highly specific enrichment of glycopeptides. The MCNTs were synthesized by a solvothermal reaction of Fe3+ loaded on the acid-treated CNTs and modified with 1-pyrenebutanoic acid N-hydroxysuccinimidyl ester (PASE) to bind aminophenylboronic acid (APBA) via an amide reaction. The introduction of PASE could bridge the MCNT and APBA, suppress the nonspecific adsorption and reduce the steric hindrance among the bound molecules. Due to the excellent structure of the MCNTs, the functionalization of PASE and then APBA on MCNTs was quite simple, specific and effective. The glycopeptides enrichment and separation with a magnetic field could be achieved by their reversible covalent binding with the boronic group of APBA-MCNTs. The exceptionally large specific surface area and the high density of boronic acid groups of APBA-MCNTs resulted in rapid and highly efficient enrichment of glycopeptides, even in the presence of large amounts of interfering nonglycopeptides. The functional MCNTs possessed high selectivity for enrichment of 21 glycopeptides from the digest of horseradish peroxidase demonstrated by MALDI-TOF mass spectrometric analysis showing more glycopeptides detected than the usual 9 glycopeptides with commercially available APBA-agarose. The proposed system showed better specificity for glycopeptides even in the presence of non-glycopeptides with 50 times higher concentration. The boronic acid functionalized MCNTs provide a promising selective enrichment platform for precise glycoproteomic analysis. Electronic supplementary information (ESI) available: EDX spectra, MALDI-TOF MS and data summary. See DOI: 10.1039/c3nr05367a

Ma, Rongna; Hu, Junjie; Cai, Zongwei; Ju, Huangxian

2014-02-01

360

Supported phosphate and carbonate salts for heterogeneous catalysis of triglycerides to fatty acid methyl esters  

NASA Astrophysics Data System (ADS)

Fatty acid methyl esters made from vegetable oil, or biodiesel, have been identified as a substitute for diesel derived from crude oil. Biodiesel is currently made using a homogeneous base catalyst to perform the transesterification of triglycerides with methanol to generate fatty acid methyl esters (FAME). The use of a homogeneous catalyst necessitates additional purification of the product and byproducts before sale, and the catalyst is consumed and discarded. The development of a heterogeneous basic catalyst for the production of FAME is desirable. Tribasic phosphate salts and dibasic carbonate salts are active for the production of FAME but generally operate as homogeneous catalysts. Supporting these phosphate and carbonate salts on mesoporous MCM-41, microporous silica gel, and nonporous a-alumina proved successful to greater or lesser degrees depending on the identity of the support and pretreatment of the support. Although these salts were supported and were active for the production of FAME from canola oil, they proved to be operating as homogeneous catalysts due to leaching of the active species off the surface of the support. Further investigation of the active species present in the tribasic phosphate catalysts identified the active support as orthophosphate, and NMR studies revealed the phosphorus to be present as orthophosphate and diphosphate in varying proportions in each catalyst. Evaluation of the acid-washing support pretreatment process revealed that the exposure of the support to acid plays a large role in the development of activity on the surface of the catalyst, but manipulation of these parameters did not prevent leaching of the active site off the surface of the catalyst. Alternate methods of support pretreatment were no more effective in preventing leaching. Tribasic phosphate supported on silica gel is not effective as a heterogeneous catalyst for FAME production from triglycerides because of the lack of stability of the phosphate on the support. The support is not stable under the reaction conditions, and alternatives should be explored to develop a heterogeneous base catalyst for the production of FAME.

Britton, Stephanie Lynne

361

Sweetening of sour natural gases by mixed-solvent absorption solubilities of ethane, carbon dioxide, and hydrogen sulfide in mixtures of physical and (5-15%) chemical solvents  

Microsoft Academic Search

Solubilities of ethane, carbon dioxide, and hydrogen sulfide in mixtures of physical and (5-15 3<) chemical solvents (i.e., propylene carbonate, N-methyl-2-pyrrolidone, and tetramethylene sulfone as physical, and monoethanolamine and diglycolamine as chemical solvents) were measured at -10° to +100°C. The results were correlated in terms of equilibrium constants and Henry's constants as a function of temperature and used to make

O. R. Rivas; J. M. Prausnitz

1979-01-01

362

Habit modification of calcium carbonate in the presence of malic acid  

SciTech Connect

The ability of malic acid to control calcium carbonate morphology has been investigated by aging calcium chloride solution in the presence of urea in a 90 deg. C bath. Malic acid favors the formation of calcite. A transition from single block to aggregate with special morphology occurs upon increasing malic acid concentration. The morphological development of CaCO{sub 3} crystal obviously depends on the starting pH. CaCO{sub 3} crystal grows from spindle seed to dumbbell in the pH regime from 7 to 11; while it evolves from spindle seed, through peanut, to sphere at pH=11.5. Both dumbbell and sphere consist of rods that are elongated along c-axis and capped with three smooth, well-defined rhombic {l_brace}1 0 4{r_brace} faces. A tentative growth mechanism is proposed based on the fractal model suggested by R. Kniep and S. Busch [Angew. Chem. Int. Ed. Engl. 35 (1996) 2624]. - Graphical abstract: Dumbbell-like CaCO{sub 3} particles obtained in the presence of malic acid.

Mao Zhaofeng [Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Huang Jianhua [Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018 (China)], E-mail: jhhuang@zstu.edu.cn

2007-02-15

363

Autocatalytic isomerizations of the two most stable conformers of carbonic acid in vapor phase: double hydrogen transfer in carbonic acid homodimers.  

PubMed

The cis-cis [(cc)] and cis-trans [(ct)] conformers of carbonic acid (H2CO3) are known as the two most stable conformers based on the different orientations of two OH functional groups present in the molecule. To explain the interconversion of the (cc)-conformer to its (ct)-conformer, the rotation of one of the two indistinguishable OH functional groups present in the (cc)-conformer has been shown until now as the effective isomerization mechanism. Moreover, the (ct)-conformer, which is slightly energetically disfavored over the (cc)-conformer, has been considered as the starting point for the decomposition of H2CO3 into CO2 and H2O molecules. Experimentally, on the other hand, the infrared (IR) and Raman spectroscopy of the crystalline H2CO3 polymorphs suggest that the most possible basic building blocks of H2CO3 polymorphs consist of only and exclusively the (cc)-conformers. However, the sublimations of these crystalline H2CO3 polymorphs result both the (cc)- and (ct)-conformers in the vapor phase with the (cc)-conformer being the major species. In this article, we first report the high level ab initio calculations investigating the energetics of the autocatlytic isomerization mechanism between the two most stable conformers of carbonic acid in the vapor phase. The calculations have been performed at the MP2 level of theory in conjunction with aug-cc-pVDZ, aug-cc-pVTZ, and 6-311++G(3df,3pd) basis sets. The results of the present study specifically and strongly suggest that double hydrogen transfer within the eight-membered cyclic doubly hydrogen-bonded (H-bonded) ring interface of the H2CO3 homodimer formed between two (cc)-conformers is ultimately the starting mechanism for the isomerization of the (cc)-conformer to its (ct)-conformer, especially, during the sublimation of the H2CO3 polymorphs, which result in the vapor phase concentration of the (cc)-conformer at the highest levels. PMID:24878165

Ghoshal, Sourav; Hazra, Montu K

2014-07-01

364

Study of a Reagent and Mediatorless Biosensor for D-Amino Acids Based on Co-Immobilized D-Amino Acid Oxidase and Peroxidase in Carbon Paste Electrodes  

Microsoft Academic Search

A biosensor for the analysis of D-amino acids is described. Carbon paste (graphite\\/paraffin oil) was chemically modified with immobilized D-amino acid oxidase and either horse-radish peroxidase or fungal peroxidase from Arthromyces ramosus. The two enzymes dissolved in buffer, together with an amine containing oligomer or polymer, were adsorbed on dry graphite. Prior to immobilization, the graphite was heat treated at

Elisabeth Johansson; György Marko-Varga; LO Gorton

1993-01-01

365

Selective dermal rejuvenation using intradermal injection of carbon dioxide and hyaluronic acid for facial wrinkles.  

PubMed

This study assessed selective dermal rejuvenation using sequential intradermal injections of carbon dioxide and hyaluronic acid as a treatment of facial wrinkles. An injection device was designed. After topical anesthesia, 0.1-mL carbon dioxide was gently injected intradermally so as to spread diffusely. A volume of 0.01- to 0.02-mL diluted hyaluronic acid was sequentially injected until the skin rose slightly. Overlapping injections were performed at 3 to 5 mm intervals. This process was repeated until the wrinkles were smoothened. This study included 36 cases of facial wrinkles in 34 patients. The follow-up period was 3 to 11 months. Temporary adverse effects were injection-site pain, mild edema, and redness. Most cases showed obvious improvement in skin thickness, elasticity, and smoothening. Complications included irregularities and hyperpigmentation in 3 cases, and 91% were highly satisfied with the antiwrinkle treatment. This method was a safe, economical, and clinically effective antiwrinkle treatment. PMID:23241811

Chin, Sae Hoon; Burm, Jin Sik; Kim, Youn Wha

2013-06-01

366

Enhancing decomposition rate of perfluorooctanoic acid by carbonate radical assisted sonochemical treatment.  

PubMed

Perfluorooctanoic acid (PFOA) is a recalcitrant organic pollutant in wastewater because of its wide range of applications. Technologies for PFOA treatment have recently been developed. In this study, PFOA decomposition by sonochemical treatment was investigated to determine the effects of NaHCO3 concentrations, N2 saturation, and pH on decomposition rates and defluorination efficiencies. The results showed that PFOA decomposition by ultrasound treatment only (150 W, 40 kHz), with or without saturated N2, was <25% after 4 h reaction. The extent and rate of PFOA decomposition and defluorination efficiencies of PFOA, however, greatly increased with the addition of carbonate radical reagents. PFOA was completely decomposed after 4h of sonochemical treatment with a carbonate radical oxidant and saturated N2. Without saturated N2, PFOA was also decomposed to a high (98.81%) degree. The highest PFOA decomposition and defluorination efficiencies occurred in N2 saturated solution containing an initial NaHCO3 concentration of 30 mM. Sonodecomposition of PFOA with CO3(-) radical was most favorable in a slightly alkaline environment (pH=8.65). There isn't any shorter-chain perfluorinated carboxylic acids detected except fluorine ions in final reaction solution. PMID:24751291

Phan Thi, Lan-Anh; Do, Huu-Tuan; Lo, Shang-Lien

2014-09-01

367

Corrosion Testing of Carbon Steel in Oxalic Acid that Contains Dissolved Iron  

SciTech Connect

Radioactive liquid waste has been stored in underground carbon steel tanks for nearly 60 years at the Savannah River Site. The site is currently in the process of removing the waste from these tanks in order to place it into vitrified, stable state for longer term storage. The last stage in the removal sequence is a chemical cleaning step that breaks up and dissolves metal oxide solids that cannot be easily pumped out of the tank. Oxalic acid (OA) will be used to chemically clean the tanks after waste retrieval is completed. The waste tanks at SRS were constructed from carbon steel materials and thus are vulnerable to corrosion in acidic media. In addition to structural impacts, the impact of corrosion on the hydrogen generated during the process must be assessed. Electrochemical and coupon immersion tests were used to investigate the corrosion mechanism at anticipated process conditions. The testing showed that the corrosion rates were dependent upon the reduction of the iron species that had dissolved in solution. Initial corrosion rates were elevated due to the reduction of the ferric species to ferrous species. At later times, as the ferric species depleted, the corrosion rate decreased. On the other hand, the hydrogen evolution reaction became more dominant.

Wiersma, Bruce J.; Mickalonis, John I.; Subramanian, Karthik H.

2012-10-11

368

Space-Based Measurements of CO2 from the Japanese Greenhouse Gases Observing Satellite (GOSAT) and the NASA Orbiting Carbon Observatory-2 (OCO-2) Missions  

NASA Technical Reports Server (NTRS)

Space-based remote sensing observations hold substantial promise for future long-term monitoring of CO2 and other greenhouse gases. The principal advantages of space based measurements include: (1) Spatial coverage (especially over oceans and tropical land) (2) Sampling density (needed to resolve CO2 weather). The principal challenge is the need for high precision To reach their full potential, space based CO2 measurements must be validated against surface measurements to ensure their accuracy. The TCCON network is providing the transfer standard There is a need for a long-term vision to establish and address community priorities (1) Must incorporate ground, air, space-based assets and models (2) Must balance calls for new observations with need to maintain climate data records.

Crisp, David

2011-01-01

369

Recovery of calcium carbonate from waste gypsum and utilization for remediation of acid mine drainage from coal mines.  

PubMed

The recovery of calcium carbonate from waste gypsum (a waste product of the reverse osmosis (RO) desalination process) was tested using sodium carbonate. Batch recovery of calcium carbonate from waste gypsum slurries by reacting with sodium carbonate under ambient conditions was used to assess the technical feasibility of CaCO(3) recovery and its use for pre-treatment of acid mine drainage (AMD) from coal mines. The effect of key process parameters, such as the slurry concentration (%) and the molar ratio of sodium carbonate to gypsum were considered. It was observed that batch waste gypsum conversion significantly increased with decrease in the slurry concentration or increase in the molar ratio of sodium carbonate to gypsum. The CaCO(3) recovered from the bench-scale batch reactor demonstrated effective neutralization ability during AMD pre-treatment compared with commercial laboratory grade CaCO(3). PMID:22828309

Mulopo, J; Radebe, V

2012-01-01

370

Photochemical production of dissolved inorganic carbon from suwannee river humic acid  

NASA Astrophysics Data System (ADS)

The photochemical mineralization of dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) is a key process in carbon cycling. Using a Suntest CPS solar simulator, Suwannee River humic acid (SRHA) was photooxidated to examine the effects of O2 levels, the wavelength of incident light, and the concentration of Fe on the photoproduction of DIC. Increasing the O2 abundance enhanced photodegradation of SRHA. The rate of DIC photoproduction under air saturation in the first 24 h (4.40 µmol/(L h)) was increased by a factor of 1.56 under O2 saturation, but fell by only 36% under N2 saturation. To evaluate the relative importance of UV-B, UV-A, and visible radiation in the photodegradation, we examined the above process using Mylar-d films and UF-3 and UF-4 plexiglass filters. The results indicated that the UV-B, UV-A and visible wavelengths accounted for 31.8%, 32.6% and 25.6%, respectively, of DIC production with simulated sunlight irradiation. The above results also indicated that photoproduction of DIC could take place in natural water at depths greater than those that UV light can reach. When 20 µmol/L desferrioxamine mesylate (DFOM, a strong Fe complexing ligand) was added, the rate of DIC photoproduction fell to 55.6% that of the original SRHA samples with 5.46 µmol/L Fe.

Wang, Xuejun; Lou, Tao; Xie, Huixiang

2009-09-01

371

Carbon storage in recombinant Escherichia coli during growth on glycerol and lactic acid.  

PubMed

A fed-batch process was studied with lactate and glycerol supply in the growth phase and glycerol supply during L-phenylalanine production with recombinant E. coli K-12. Lactic acid feeding was necessary for growth because the genes encoding the PEP-consuming pyruvate kinase isoenzymes (pykA, pykF) have been deleted. An unexpected glucose efflux (67.6?±?2.3?mgGlucose ?gCDW (-1) ) was measured after the cells were harvested and resuspended in a mineral medium for metabolic perturbation experiments. As the efflux prohibited the application of these experiments, characterization of intracellular carbon storage was necessary. Therefore, two genetically engineered strains (one lacking glycogen metabolism and another additionally lacking trehalose synthesis) were applied in the fed-batch process. Trehalose synthesis and accumulation from lactate was clearly identified as the source for glucose efflux after cell harvest and resuspension. Cultivations of strains with active pyruvate kinase successfully identified lactate as the carbon source causing intracellular trehalose storage. The usage of glycerol as sole carbon source during the whole process enabled an improved process performance and inhibited trehalose accumulation. Overall, this setup allows the application of perturbation experiments. Biotechnol. Bioeng. 2014;111: 2508-2519. © 2014 Wiley Periodicals, Inc. PMID:24902947

Weiner, Michael; Tröndle, Julia; Albermann, Christoph; Sprenger, Georg A; Weuster-Botz, Dirk

2014-12-01

372

A pharmaceutical product as corrosion inhibitor for carbon steel in acidic environments.  

PubMed

A pharmaceutical product, Trimethoprim (TMP), IUPAC name: 5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diamine was investigated, as inhibitor to prevent carbon steel corrosion in acidic environments. The study was performed using weight loss and electrochemical measurements, in temperatures ranging between 25-55°C. The surface morphology before and after corrosion of carbon steel in 1.0 M HCl solution in the presence and absence of TMP was evaluated using scanning electron microscopy (SEM). The inhibition efficiency (IE) increased with the increasing of the inhibitor concentration, reaching a maximum value of 92% at 25°C and 0.9 mM TMP, and decreased with increasing temperature. The inhibition of carbon steel corrosion by TMP can be attributed to the adsorption ability of inhibitor molecules onto the reactive sites of the metal surface. The adsorption is spontaneous and it is best described by the Langmuir isotherm. The apparent activation energy (E(a)) for the corrosion process in the absence and presence of TMP was evaluated from Arrhenius equation, to elucidate its inhibitive properties. PMID:23043337

Samide, Adriana

2013-01-01

373

Formation of calcium carbonate films on chitosan substrates in the presence of polyacrylic acid  

SciTech Connect

In this investigation, chitosan membranes with different surface average degrees of deacetylation (DA) are prepared and then are employed as the support matrix to culture calcium carbonate (CaCO{sub 3}). In the presence of high concentration of polyacrylic acid (PAA), the CaCO{sub 3} films obtained on the surface of all chitosan films mainly consisted of vaterite, which suggests the presence of bulk PAA plays an overwhelming part in stabilizing the vaterite. As a comparison, the influences of active groups indicate that only in case of low concentration PAA the thin CaCO{sub 3} films grown on chitosan with 8% DA mainly consisted of vaterite owing to the strong nucleation ability of -NH{sub 2} group, whereas, for those grown on chitosan with 80% DA the CaCO{sub 3} films mainly consisted of aragonite. A more complex scenario revealed that in the case of intermediate concentration of PAA the formed polymorphs behave as mixtures of vaterite and aragonite. - Graphical abstract: Chitosan membranes with different degrees of deacetylation (DA) are employed as support to culture calcium carbonate (CaCO{sub 3}). In high concentration of polyacrylic acid (PAA), the CaCO{sub 3} films obtained consisted of vaterite. However, the CaCO{sub 3} film grown on chitosan with 8% DA mainly consisted of vaterite as opposed to aragonite for chitosan with 8% DA. The schematic presentation of the formation of calcium carbonate on chitosan films with different degrees of acetylation in the presence of PAA with low-, mid- and high concentrations.

He, Linghao; Xue, Rui [Zhengzhou University of Light Industry Henan Provincial Key Laboratory of Surface and Interface Science, Henan, Zhengzhou 450002 (China); Song, Rui, E-mail: rsong@gucas.ac.c [Zhengzhou University of Light Industry Henan Provincial Key Laboratory of Surface and Interface Science, Henan, Zhengzhou 450002 (China); College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, Beijing 100049 (China)

2009-05-15

374

Alkylation of CH acids in the presence of potassium carbonate. III. Alkylation of CH acids by 2,3-substituted 1,4-dibromo-2-butenes  

SciTech Connect

During the cycloalkylation of CH acids by 2,3-substituted (methyl-chlorine) 1,4-dibromo-2-butenes the direction of intramolecular C- and O-alkylation depends both on steric and on electronic factors. The introduction of substituents into the alkylating agent and the presence of acetyl groups in the initial CH acids promote regiospecific intramolecular O-alkylation. It was found that the initial alkylation of the enolizing CH acids with 1,4-dibromo-2-methyl-2-butene in the presence of potassium carbonate takes place with high regioselectivity at the unsubstituted end of the butene chain.

Vardapetyan, A.A.; Khachatryan, D.S.; Morlyan, N.M.

1988-12-10

375

Closure device for lead-acid batteries  

DOEpatents

A closure device for lead-acid batteries includes a filter of granulated activated carbon treated to be hydrophobic combined with means for preventing explosion of emitted hydrogen and oxygen gas. The explosion prevention means includes a vertical open-end tube within the closure housing for maintaining a liquid level above side wall openings in an adjacent closed end tube. Gases vent from the battery through a nozzle directed inside the closed end tube against an impingement surface to remove acid droplets. The gases then flow through the side wall openings and the liquid level to quench any possible ignition prior to entering the activated carbon filter. A wick in the activated carbon filter conducts condensed liquid back to the closure housing to replenish the liquid level limited by the open-end tube.

Ledjeff, Konstantin (Schwalbach, DE)

1983-01-01

376

Zevenhoven & Kilpinen FLUE GASES and FUEL GASES 19.6.2001 2-1 Chapter 2 Flue gases and  

E-print Network

concentrations of the combustion products water (H2O) and carbon dioxide (CO2). More concern, however, goes should be included in the list of species not be emitted into the atmosphere carelessly. CO2 atmosphere at ground-level. The formation of ground-level ozone from traffic exhaust gases during sunny

Zevenhoven, Ron

377

Modeling of radiative properties of an Oxyfuel atmosphere with a weighted sum of gray gases for variable carbon dioxide and water vapor concentrations  

Microsoft Academic Search

The partial pressure of carbon dioxide in the flue gas of an Oxyfuel combustion process is significantly increased in comparison with conventional air-blown firing. Depending on the moisture content of the fuel and the type of flue gas recirculation (either wet or dry), the partial pressure of water vapor varies for Oxyfuel atmospheres. The calculation of the heat transfer by

Sebastian Rehfeldt; Christian Kuhr; Martin Ehmann; Christian Bergins

2011-01-01

378

Emissions of Greenhouse Gases in the United States 1997  

NSDL National Science Digital Library

The Emissions of Greenhouse Gases in the United States 1997 publication was prepared under the guidance of Mary Hutzler, Director of the Office of Integrated Analysis and Forecasting, Energy Information Administration. This report "presents the latest estimates of emissions for carbon dioxide, methane, nitrous oxide, and other greenhouse gases." The paper states that 82% of U.S. greenhouse gas emissions are caused by coal, petroleum, and natural gas. Gases such as hydroflourocarbons (HFCs), perflourocarbons (PFCs), sulfur hexafluoride, nitrous oxide, methane, and other carbon dioxide gases comprise the other 18% of U.S. emissions. The paper provides an in-depth analysis of Carbon Dioxide Emissions, Methane Emissions, Nitrous Oxide Emissions, Halocarbons and Other Gases, and Land Use Issues, among others.

379

Removal of boron from aqueous solution using magnetic carbon nanotube improved with tartaric acid  

PubMed Central

Boron removal capacity of multi-walled carbon nanotubes (MWCNTs) modified with tartaric acid was investigated in this study. Modification of MWCNTs with tartaric acid was confirmed by Boehm surface chemistry method and fourier transform infra-red (FT-IR) spectroscopy. Experiments were performed to determine the adsorption isotherm and adsorption thermodynamic parameters of boron adsorption on tartaric acid modified MWCNTs (TA-MWCNTs). The effect of variables including initial pH, dosage of adsorbent, contact time and temperature was investigated. Analysis of data showed that adsorption equilibrium could be better described by Freundlich isotherm and the maximum adsorption capacities obtained at the pH of 6.0 was 1.97 mg/g. The estimated thermodynamic values of free energy (?G°), entropy (?S°) and enthalpy (?H°) indicated a spontaneous and an endothermic process. Furthermore, the TA-MWCNTs was magnetized for separation of boron-contaminated adsorbent from aqueous solution by applying magnetic field. The results showed that magnetic TA-MWCNTs particles were separated effectively after adsorption from contaminated water. PMID:24393401

2014-01-01

380

Carbon Footprint  

NSDL National Science Digital Library

This website has interactive tools to calculate your carbon footprint, which is a way to measure how much carbon dioxide and other greenhouse gases are produced by your activities. This site also contains specific recommendations for reducing and off-setting your carbon footprint, as well as links to news and information about global warming.

Ltd, Carbon F.

381

ANALYSIS OF PROTOCOL GASES  

EPA Science Inventory

In 1992, EPA's Atmospheric Research and Exposure Assessment Laboratory initiated a nationwide QA program on the suppliers of EPA Protocol Gases. he program has three goals: to increase the acceptance and use of Protocol Gases by the air monitoring community, to provide a QA check...

382

Biomass - Investigating Gases  

NSDL National Science Digital Library

In this lab activity students generate their own biomass gases by heating wood pellets or wood splints in a test tube. They collect the resulting gases and use the gas to roast a marshmallow. Students also evaluate which biomass fuel is the best by their own criteria or by examining the volume of gas produced by each type of fuel.

Benson, Eric E.; Highfill, Melissa; Development, Us D.

383

Toxicity of pyrolysis gases from polyether sulfone  

NASA Technical Reports Server (NTRS)

A sample of polyether sulfone was evaluated for toxicity of pyrolysis gases, using the toxicity screening test method developed at the University of San Francisco. Animal response times were relatively short at pyrolysis temperatures of 600 to 800 C, with death occurring within 6 min. The principal toxicant appeared to be a compound other than carbon monoxide.

Hilado, C. J.; Olcomendy, E. M.

1979-01-01

384

The use of sulphuric acid-carbonization products of sugar beet pulp in Cr(VI) removal  

Microsoft Academic Search

A carbon rich adsorbent prepared from the reaction of sugar beet pulp with sulphuric acid and gas formed during carbonization process have been studied for Cr(VI) removal from aqueous solutions. The SO2 rich gas was shown to be an excellent Cr(VI) reductant. The equilibrium and kinetic studies were conducted by using the carbonaceous adsorbent derived from sugar beet pulp. The

H. Soner Altundogan; Nurdan Bahar; Buket Mujde; Fikret Tumen

2007-01-01

385

Thermal metamorphism of primitive meteorites. VIII - Noble gases, carbon and sulfur in Allende /C3/ meteorite heated at 400-1000 C  

NASA Technical Reports Server (NTRS)

Noble gases, C and S, are lost from Allende samples heated for 1 week at temperatures of 400-1000 C in a low pressure environment. In the extreme, losses of He-3 and He-4 are about 100 x while for C, S and Ne, Ar and Kr isotopes and Xe-132 these are less than or equal to 10 x. Except for He, these losses are less severe than those of Bi or Tl from samples heated in the same runs. Significant He, Ne and Ar isotopic fractionation during heating indicates preferential outgassing of specific reservoirs. Next to He, Ar-40 is the most labile of those species considered here but still less so than Bi or Tl. L-group (but not H- or LL-group) chondrites may have lost mobile elements like Tl while being outgassed after late impact-associated heating. A less likely alternative involving a collateral relation between condensation conditions and depth in a parent object may also explain the L-group trend.

Herzog, G. F.; Gibson, E. K., Jr.; Lipschutz, M. E.

1979-01-01

386

Effects of propionate and methylmalonate on conversions of acetate, butyrate, and D(-)-3-hydroxybutyrate to fatty acids and carbon dioxide by mammary tissue slices of goats  

SciTech Connect

Incorporations of (1-carbon-14) acetate, (1-carbon-14) propionate, n-(1-carbon-14) butyrate, and D(-)-3-hydroxy(3-carbon-14) butyrate into individual milk fatty acids and their conversion to carbon dioxide were studied in vitro with caprine mammary tissue slices in the presence and absence of propionate and methylmalonate. Neither propionate nor methylmalonate affected incorporation of these substances into fatty acids. In a decreasing order butyrate, acetate, propionate, and D(-)-3-hydroxybutyrate were converted to carbon dioxide. Acetate had the highest incorporation rate into fatty acids followed by D(-)-3-hydroxybutyrate, butyrate, and propionate. Labeled propionate was incorporated mainly into odd-numbered fatty acids. Results do not support the theory that either propionate or its metabolite, methylmalonate, inhibit de novo synthesis of fatty acids in the mammary gland in relation to the etiology of low milk fat syndrome.

Emmanuel, B.; Kennelly, J.J.

1985-03-01

387

Arachidonic acid-dependent carbon-eight volatile synthesis from wounded liverwort (Marchantia polymorpha).  

PubMed

Eight-carbon (C8) volatiles, such as 1-octen-3-ol, octan-3-one, and octan-3-ol, are ubiquitously found among fungi and bryophytes. In this study, it was found that the thalli of the common liverwort Marchantia polymorpha, a model plant species, emitted high amounts of C8 volatiles mainly consisting of (R)-1-octen-3-ol and octan-3-one upon mechanical wounding. The induction of emission took place within 40min. In intact thalli, 1-octen-3-yl acetate was the predominant C8 volatile while tissue disruption resulted in conversion of the acetate to 1-octen-3-ol. This conversion was carried out by an esterase showing stereospecificity to (R)-1-octen-3-yl acetate. From the transgenic line of M. polymorpha (des6(KO)) lacking arachidonic acid and eicosapentaenoic acid, formation of C8 volatiles was only minimally observed, which indicated that arachidonic and/or eicosapentaenoic acids were essential to form C8 volatiles in M. polymorpha. When des6(KO) thalli were exposed to the vapor of 1-octen-3-ol, they absorbed the alcohol and converted it into 1-octen-3-yl acetate and octan-3-one. Therefore, this implied that 1-octen-3-ol was the primary C8 product formed from arachidonic acid, and further metabolism involving acetylation and oxidoreduction occurred to diversify the C8 products. Octan-3-one was only minimally formed from completely disrupted thalli, while it was formed as the most abundant product in partially disrupted thalli. Therefore, it is assumed that the remaining intact tissues were involved in the conversion of 1-octen-3-ol to octan-3-one in the partially disrupted thalli. The conversion was partly promoted by addition of NAD(P)H into the completely disrupted tissues, suggesting an NAD(P)H-dependent oxidoreductase was involved in the conversion. PMID:25174554

Kihara, Hirotomo; Tanaka, Maya; Yamato, Katsuyuki T; Horibata, Akira; Yamada, Atsushi; Kita, Sayaka; Ishizaki, Kimitsune; Kajikawa, Masataka; Fukuzawa, Hideya; Kohchi, Takayuki; Akakabe, Yoshihiko; Matsui, Kenji

2014-11-01

388

Biological treatment of acidic coal refuse using sulphate-reducing bacteria with chicken manure as carbon source.  

PubMed

The performance of using chicken manure as carbon source to promote sulphate-reducing bacteria (SRB) activity within acidic coal refuse to prevent the generation of acidic leachate was investigated in batch and column bioreactors. The bioreactors showed satisfactory performance in biological sulphate reduction, evidenced by the increase in effluent pH, high removal efficiencies of sulphate and metals, and the presence of large numbers of SRB. Scanning electron microscope-energy dispersive spectrometry (EDS) analysis of the formed precipitate indicated the formation of metal sulphides. Chicken manure was observed to play an important role in this treatment, which could not only provide carbon source but also reduce the adverse effect of strong acidity and metal toxicity on SRB activity. Metal removal could be mainly attributed to sulphides precipitation and sorption to chicken manure. This study indicated that SRB with chicken manure could be a novel alternative used for the prevention of acidic leachate from coal refuse. PMID:25189842

Zhang, Mingliang; Wang, Haixia

2014-12-01

389

Possible role for abscisic acid in regulation of photosynthetic and photorespiratory carbon metabolism in barley leaves. [Hordeum vulgare  

SciTech Connect

The influence of abscisic acid (ABA) on carbon metabolism, rate of photorespiration, and the activity of the photorespiratory enzymes ribulose bisphosphate oxygenase and glycolate oxidase in 7-day-old barley seedlings (Hordeum vulgare L. var. Alfa) was investigated. Plants treated with ABA had enhanced incorporation of labeled carbon from /sup 14/CO/sub 2/ into glycolic acid, glycine, and serine, while /sup 14/C incorporation into 3-phosphoglyceric acid and sugarphosphate esters was depressed. Parallel with this effect, treated plants showed a rise in activity of RuBP oxygenase and glycolic acid oxidase. The rate of photorespiration was increased twofold by ABA treatment at IO/sup -6/ molar while the CO/sub 2/-compensation point increased 46% and stomatal resistance increased more than twofold over control plants.

Popova, L.P.; Tsonev, T.D.; Vaklinova, S.G.

1987-04-01

390

Zevenhoven & Kilpinen Greenhouse Gases, Ozone-Depleting Gases 19.6.2001 9-1 Figure 9.1 Increasing world population  

E-print Network

accepted that carbon dioxide and several other gases are involved in physical and chemical processes in the earth's upper troposphere and stratospere (see Figure 4.2) that may result in global climate change in gasification product gases. Concentrations in flue gases from power plants are ~ 4%- volCO2 fornaturalgas

Laughlin, Robert B.

391

Carbon13 kinetic isotope effects in the decarbonylation of lactic acid of natural isotopic composition in phosphoric acid medium  

Microsoft Academic Search

The13C kinetic isotope effect fractionation in the decarbonylation of lactic acid (LA) of natural isotopic composition by concentrated phosphpric acids (PA) and by 85% H3PO4 has been studied in the temperature interval of 60–150°C. The values of the13C(1) isotope effects in the decarbonylation of lactic acid in 100% H3PO4, in pyrophosphoric acid and in more concentrated phosphoric acids are intermediate

M. Zieli?ski; G. Czarnota; H. Papiernik-Zieli?ska; G. Kasprzyk; L. Gumó?ka; W. Städter

1993-01-01

392

Hybrid lead-acid battery with reticulated vitreous carbon as a carrier- and current-collector of negative plate  

Microsoft Academic Search

Bare reticulated vitreous carbon (RVC) plated electrochemically with thin layer of lead was investigated as a negative plate carrier- and current-collector material for lead-acid batteries. Hybrid flooded single cell lead-acid batteries containing one negative plate based on a new type (RVC or Pb\\/RVC) of carrier\\/current-collector and two positive plates based on Pb–Ca grid collectors were assembled and subjected to charge\\/discharge

A. Czerwi?ski; S. Obr?bowski; J. Kotowski; Z. Rogulski; J. Skowro?ski; M. Bajsert; M. Przysta?owski; M. Buczkowska-Biniecka; E. Jankowska; M. Baraniak; J. Rotnicki; M. Kopczyk

2010-01-01

393

The selective electrochemical detection of homocysteine in the presence of glutathione, cysteine, and ascorbic acid using carbon electrodes.  

PubMed

The detection of homocysteine, HCys, was achieved with the use of catechol via 1,4-Michael addition reaction using carbon electrodes: a glassy carbon electrode and a carbon nanotube modified glassy carbon electrode. The selective detection of homocysteine was investigated and achieved in the absence and presence of glutathione, cysteine and ascorbic acid using cyclic voltammetry and square wave voltammetry. A calibration curve of homocysteine detection was determined and the sensitivity is (0.20 ± 0.02) ?A ?M(-1) and the limit of detection is 660 nM within the linear range. Lastly, commercially available multi walled carbon nanotube screen printed electrodes were applied to the system for selective homocysteine detection. This work presents a potential practical application towards medical applications as it can be highly beneficial towards quality healthcare management. PMID:24918102

Lee, P T; Lowinsohn, D; Compton, R G

2014-08-01

394

Hydrogen oxidation on gas diffusion electrodes for phosphoric acid fuel cells in the presence of carbon monoxide and oxygen  

SciTech Connect

Hydrogen oxidation has been studied on a carbon-supported platinum gas diffusion electrode in a phosphoric acid electrolyte in the presence of carbon monoxide and oxygen in the feed gas. The poisoning effect of carbon monoxide present in the feed gas was measured in the temperature range from 80 to 150 C. It was found that throughout the temperature range, the potential loss due to the CO poisoning can be reduced to a great extent by the injection of small amounts of gaseous oxygen into the hydrogen gas containing carbon monoxide. By adding 5 volume percent (v/o) oxygen, an almost CO-free performance can be obtained for carbon monoxide concentrations up to 0.5 v/o CO at 130 C, 0.2 v/o CO at 100 C, and 0.1 v/o CO at 80 C, respectively.

Gang, X.; Qingfeng, L.; Hjuler, H.A.; Bjerrum, N.J. [Technical Univ. of Denmark, Lyngby (Denmark)

1995-09-01

395

Mechanical characterization and morphology of polylactic acid /liquid natural rubber filled with multi walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

In this paper the polymer nanocomposite of multi-walled carbon nanotubes (MWCNTs) nanoparticles was incorporated with polylactic acid (PLA) and liquid natural rubber (LNR) as compatibilizer were prepared via melt blending method. The effect of MWCNTs loading on the tensile and impact properties of nanocomposites was investigated. The result has shown that the sample with 3.5 wt % of MWCNTs exhibited higher tensile strength, Young's modulus and impact strength. The elongation at break decreased with increasing percentage of MWCNTs. The SEM micrographs confirmed the effect of good dispersion of MWCNTs and their interfacial bonding in PLA/LNR composites. The improved dispersion of MWCNTs can be obtained due to altered interparticle interactions, MWCNTs-MWCNTs and MWCNTs-matrix networks are well combined to generate the synergistic effect of the system as shown by SEM micrographs which is improved the properties significantly.

Ali, Adilah Mat; Ahmad, Sahrim Hj.

2013-11-01

396

Synthesis of highly dispersed and active palladium/carbon nanofiber catalyst for formic acid electrooxidation  

NASA Astrophysics Data System (ADS)

Highly dispersed and active palladium/carbon nanofiber (Pd/CNF) catalyst is synthesized by NaBH4 reduction with trisodium citrate as the stabilizing agent. The obtained Pd/CNF catalyst is characterized by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The results show that the Pd nanoparticles with an average particle size of ca. 3.8 nm are highly dispersed on the CNF support even with a small ratio of citrate to Pd precursor, which is believed to be due to the pH adjustment of citrate stabilized colloidal Pd nanoparticles. The cyclic voltammetry and chronoamperometry techniques show that the obtained Pd/CNF catalyst exhibits good catalytic activity and stability for the electrooxidation of formic acid.

Qin, Yuan-Hang; Yue-Jiang; Yang, Hou-Hua; Zhang, Xin-Sheng; Zhou, Xing-Gui; Niu, Li; Yuan, Wei-Kang

2011-05-01

397

Controlled graft copolymerization of lactic acid onto starch in a supercritical carbon dioxide medium.  

PubMed

This work presents a new approach for the synthesis of a starch-g-poly L-lactic acid (St-g-PLA) copolymer via the graft copolymerization of LA onto starch using stannous 2-ethyl hexanoate (Sn(Oct)2) as a catalyst in a supercritical carbon dioxide (scCO2) medium. The effects of several process parameters, including the pressure, temperature, scCO2 flow rate and reaction time, on the polymerization yield and grafting degree were studied. Amorphous graft St-g-PLA copolymers with increased thermal stability and processability were produced with a high efficiency. The maximum grafting degree (i.e., 52% PLA) was achieved with the following reaction conditions: 6h, 100°C, 200bar and a 1:3 (w/w) ratio of St/LA. It was concluded that these low cost biobased graft biopolymers are potential candidates for several environment-friendly applications. PMID:25263875

Salimi, Kouroush; Yilmaz, Mehmet; Rzayev, Zakir M O; Piskin, Erhan

2014-12-19

398

Interaction of D-Amino Acid Oxidase with Carbon Nanotubes: Implications in the Design of Biosensors  

PubMed Central

We have investigated the interaction of D-amino acid oxidase (DAAO) with single walled carbon nanotubes (CNT) by spectroscopic ellipsometry. Dynamic adsorption experiments were performed at different experimental conditions. In addition, the activity of the enzyme adsorbed at different conditions was studied. Our results indicate that DAAO can be adsorbed to CNT at different pH values and concentrations by a combination of hydrophobic and electrostatic interactions. Considering that the highest enzymatic activity was obtained by adsorbing the protein at pH 5.7 and 0.1 mg.mL?1, our results indicate that DAAO can adopt multiple orientations on the surface; which are ultimately responsible for significant differences in catalytic activity. PMID:19132842

Mora, Maria F.; Giacomelli, Carla E.; Garcia, Carlos D.

2009-01-01

399

Mitigation of surface damage growth by hydrofluoric acid etching combined with carbon dioxide laser treatment  

NASA Astrophysics Data System (ADS)

Damage sites as large as 600 ?m in fused silica surface were successfully mitigated with a new protocol by hydrofluoric acid (HF) etching combined with carbon dioxide laser treatment. The damage sites were first etched in 40% HF solution to blunt the fractures, and then the etched damage sites were smoothed with a CO2 laser. It has been found that the etching rate of damaged material in the lateral direction is larger than in the longitudinal direction; thus, an optimized etching time was chosen to etch the damage sites based on the etching ratio. Three types of damage test methods were used to confirm the mitigation efficiency of the protocol. The results indicate that the damage resistance capability of mitigated sites can recover to the level of pristine substrate.

Jiang, Yong; Yuan, Xiaodong; He, Shaobo; Zheng, Wanguo; Wang, Haijun; Lü, Haibing; Ren, Wei; Luo, Chengsi; Liu, Chunming; Xiang, Xia; Zu, Xiaotao

2012-08-01

400

Corrosion Inhibition of Carbon Steel by New Thiophene Azo Dye Derivatives in Acidic Solution  

NASA Astrophysics Data System (ADS)

Inhibition of carbon steel corrosion in 2 M hydrochloric acid (HCl) solution by thiophene azo dye derivatives were studied using weight loss, electrochemical frequency modulation (EFM), and atomic absorption techniques. The experimental data suggest that the inhibition efficiency increases with increasing inhibitors concentration in presence of 103 ?M potassium iodide (KI). This is due to synergistic effect. Thus, the experimental results suggested that the presence of these anions in the solution stabilized the adsorption of inhibitors molecules on the metal surface and improved the inhibition efficiency. The results of EFM experiments are a spectrum of current response as a function of frequency. The corrosion rate and Tafel parameters can be obtained with measurement by analyzing the harmonic frequencies. The adsorption of the inhibitors on metal surface obeys the Langmuir adsorption isotherm. The surface of metal examined using Fourier transform infrared and ultraviolet spectroscopy. Quantum chemical calculations were carried out and relations between computed parameters and experimental inhibition efficiency were discussed.

El-Haddad, Mahmoud N.; Fouda, A. S.; Mostafa, H. A.

2013-08-01

401

Trace Gases, CO2, Climate, and the Greenhouse Effect.  

ERIC Educational Resources Information Center

Reports carbon dioxide and other trace gases can be the cause of the Greenhouse Effect. Discusses some effects of the temperature change and suggests some solutions. Included are several diagrams, graphs, and a table. (YP)

Aubrecht, Gordon J., II

1988-01-01

402

Catalytic wet air oxidation of acetic acid on carbon-supported ruthenium catalysts  

SciTech Connect

Ruthenium catalysts prepared by ion exchange of active carbons and high-surface-area graphites are active for the wet air oxidation of aqueous solutions of acetic acid (5-20 g/liter). A total conversion into CO{sub 2} can be achieved between 448 and 473 K using air as oxidizing agent. No leaching of ruthenium can be detected which indicates that the reaction proceeds on the heterogeneous catalysts. For the same particle size (1 nm), graphite-supported ruthenium catalysts are much more active (up to 0.4 mol h{sup -1} g{sub RU}{sup -1} at 473 K in a stirred batch reactor pressurized with air at 10 MPa) than active carbon-supported catalysts. The lower activities of the latters could be due to internal diffusion limitation since the 1-nm Ru particles are located inside the micropores. However, graphite-supported catalysts might be intrinsically more active because of an electron transfer from graphite to metal particles which would increase the resistance of ruthenium to oxygen poisoning. It was also shown that the activity of ruthenium is particle size dependent: the smaller the sizes, the lower the activities. This effect could be interpreted by the higher adsorption energy of oxygen on the small particles which produces a poisoning of the metal surface. From measurements of the reaction rates on the Ru/HSAG graphite catalyst at different temperatures, pressures, and acetic acid concentrations, it was established that the reaction orders were zero and 0.65 with respect to the concentration and oxygen pressure, respectively; the activation energy of the reaction was 100.5 kJ mol{sup -1}. An equation describing the reaction kinetics was proposed. 23 refs., 4 figs., 2 tabs.

Gallezot, P.; Chaumet, S.; Perrard, A. [Institut de Recherches sur la Catalyse, Villeurbanne (France)] [and others] [Institut de Recherches sur la Catalyse, Villeurbanne (France); and others

1997-05-01

403

Initial characterization of carbon flows through microbial communities in Beowulf spring, an acidic hot spring in Yellowstone National Park  

NASA Astrophysics Data System (ADS)

Beowulf Springs are acidic, sulfidic hot springs in Yellowstone National Park. Visual inspection of the springs reveals distinct geochemical regions starting with a sulfur deposition zone followed by a transition to iron oxide deposition downstream. The relatively rapid sulfur and iron oxide deposition rates in this spring suggests the processes are microbially mediated (since, for instance, abiotic iron oxidation is kinetically slow at this temperature and pH) and previous diversity studies identify microbial communities consistent with the observed metabolic products (namely sulfur and iron oxide). While the energetics of sulfide and iron oxidation are sufficient for supporting microbial activity, a suitable carbon source remains undocumented. The temperatures in Beowulf approach 80 °C, which is above the photosynthetic upper temperature limit thus precluding photosynthetic-based autotrophy within the spring itself. Observed potential carbon sources in Beowulf include dissolved inorganic carbon, dissolved organic carbon, and methane. We are employing geochemical and stable isotope techniques to assess carbon inventories in the system. With thorough analysis we hope to identify both the major carbon stores in the system and track how they are transferred between microbial components in Beowulf. Initial stable isotope measurements focused on bulk isotope analysis of major carbon pools; both directly in the spring and in surrounding areas that may affect the spring water through runoff or ground water migration. We are analyzing bulk carbon isotopes of different microbial groups in the spring, the dissolved organic and inorganic carbon in the spring, and surrounding soils and potential plant inputs. Isotopic similarity between dissolved organic carbon and soil organic carbon is consistent with a common carbon source (local vegetation) but has not yet been confirmed as such. Correlation between ?13C of microbial biomass and dissolved organic carbon are suggestive of a heterotrophic component in the system but the lack of a direct one-to-one isotopic correlation suggest there is an additional carbon input. We are performing a series of stable isotope probing experiments with microbial mats extracted from the spring to determine whether autotrophy may be a major carbon source in the system. Identifying the major active carbon pools and potential geochemical and microbial carbon links will illuminate carbon cycling in this system and should provide insights into how energy is transferred from key chemolithotrophic reactions to other components of the microbial system.

Kreuzer, H.; Moran, J.; Ehrhardt, C.; Melville, A.; Kranz, A.; Inskeep, W. P.

2011-12-01

404

Identification and yield of carbonic acid and formaldehyde in irradiated ices  

NASA Technical Reports Server (NTRS)

Carbonic acid, (OH)2CO, was tentatively identified in the IR spectrum of a proton irradiated CO2 + H2O ice mixture. In this report, we present additional evidence for a more definitive identification of (OH)2CO with (1) the infrared spectrum of a residue obtained by proton irradiation of CO2 + D2O ice mixture, and (2) the IR spectra of solid phases of formaldehyde (H2CO), acetone (CH3)2CO, and dimethyl carbonate (OCH3)2CO, which are structurally similar to (OH)2CO. IR characteristics (peak frequencies and complex refractive indices of the compounds in point 2) are also reported. In particular, the integrated absorption coefficients for the C-O band for the compounds in point 2 do not vary by more than 20 percent. Based on these values, we estimate the yields of H2CO and (OH)2CO by proton irradiation or ice mixtures. Both H2CO and (OH)2CO are possible irradiation products of cometary and planetary ices.

Dellorusso, Neil; Khanna, R. K.; Moore, M. H.

1993-01-01

405

Carbon-supported PtAu alloy nanoparticle catalysts for enhanced electrocatalytic oxidation of formic acid  

NASA Astrophysics Data System (ADS)

The understanding of the electrocatalytic activity of bimetallic nanoparticle catalysts requires the ability to precisely control the composition and phase properties. In this report, we describe a new strategy in the preparation of a series of carbon supported platinum-gold bimetallic nanoparticles with various bimetallic compositions which were loaded onto a carbon black support and subjected subsequently by thermal treatment (Pt100-mAum/C). The Pt100-mAum/C catalysts are characterized by X-ray diffraction (XRD), transmission electron spectroscopy (TEM), and induced coupled plasma-atomic emission spectroscopy (ICP-AES). The XRD pattern for the bimetallic nanoparticles shows single-phase alloy character. This ability enabled us to establish the correlation between the bimetallic composition and the electrocatalytic activity for formic acid (FA) electrooxidation. The electrocatalytic activities of the catalysts toward FA oxidation reaction are shown to strongly depend on the bimetallic PtAu composition. Within a wide range of bimetallic composition, the Pt50Au50/C catalyst shows the highest electrocatalytic activity for the FA oxidation, with a mass activity eight times higher than that of Pt/C. The high performance of the PtAu/C catalyst can be ascribed to the increased selectivity toward the FA dehydrogenation at the decreased availability of adjacent Pt atoms.

Chen, Guoqin; Li, Yunhua; Wang, Dong; Zheng, Li; You, Guirong; Zhong, Chuan-Jian; Yang, Lefu; Cai, Fan; Cai, Junxiu; Chen, Bing H.

2011-10-01

406

Adsorption removal of acid black 1 from aqueous solution using ordered mesoporous carbon  

NASA Astrophysics Data System (ADS)

A novel ordered mesoporous carbon CMK-3 and synthetic CMK-3 containing nitrogen functional groups by ammonia-treated were applied for acid black 1(AB1) dye adsorption. The ammonia-treated(chemical vapor deposition method) before and after CMK-3 were characterized by using a Micrometitics ASAP 2020 surface area analyzer (ASAP 2020), Fourier transform infrared spectrophotometer (FT-IR), X-ray Photoelectron Spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscope (SEM) and equilibrium studies. This result indicates that the prepared CMK-3 and modified CMK-3 were almost uniform, as rope-like domains and their uniform mesopore with diameter centered at 3.2 nm and 3.7 nm. The FIIR analysis depicted that the presence of a variety of new basic functional groups on the modified CMK-3 surface. Several effect variables of pH, dye concentration and temperature were studied. The pseudo second-order model showed the ?tter well to agree with the kinetic data. The experimental data were analyzed by the Langmuir and Freundlich models, with the latter found to closely the isotherm model. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The results show that CMK-3 using ammonia gas modified by thermal treatment system is an effective method to improvement capacity as it shows the highest adsorption capacity of AB1, as compared to the unmodified CMK-3 and the bamboo-based carbon, respectively.

Peng, Xiaoming; Hu, Xijun; Fu, Dafang; Lam, Frank L. Y.

2014-03-01

407

Gas-phase preparation of carbonic Acid and its monomethyl ester.  

PubMed

Carbonic acid (H2 CO3 ), an essential molecule of life (e.g., as bicarbonate buffer), has been well characterized in solution and in the solid state, but for a long time, it has eluded its spectral characterization in the gas phase owing to a lack of convenient preparation methods; microwave spectra were recorded only recently. Here we present a novel and general method for the preparation of H2 CO3 and its monomethyl ester (CH3 OCO2 H) through the gas-phase pyrolysis of di-tert-butyl and tert-butyl methyl carbonate, respectively. H2 CO3 and CH3 OCO2 H were trapped in noble-gas matrices at 8?K, and their infrared spectra match those computed at high levels of theory [focal point analysis beyond CCSD(T)/cc-pVQZ] very well. Whereas the spectra also perfectly agree with those of the vapor phase above the ?-polymorph of H2 CO3 , this is not true for the previously reported ?-polymorph. Instead, the vapor phase above ?-H2 CO3 corresponds to CH3 OCO2 H, which sheds new light on the research that has been conducted on molecular H2 CO3 over the last decades. PMID:25196920

Reisenauer, Hans Peter; Wagner, J Philipp; Schreiner, Peter R

2014-10-27

408

Volcanic Gases and Their Effects  

MedlinePLUS

Volcanic Gases and Their Effects Magma contains dissolved gases that are released into the atmosphere during eruptions. Gases are also released from magma that either remains below ground (for example, as ...

409

Carbon Dioxide Information Analysis Center and World Data Center-A for atomspheric trace gases: Catalog of data bases and reports  

SciTech Connect

This document provides information about the many reports and other materials made available by the US Department of Energy`s Global Change Research Program (GCRP). Section A provides information about the activities, scope, and direction of the GCRP; Sections B,C, D, and E contain information about research that has been sponsered by GCRP; Sections F and G contains information about the numeric data packages and computer model pa kages the have been compiled by the GCRP; Section H describes reports about research dealing with the responses of vegetation to carbon dioxide; and Section I conatins reports from various workshops, symposia, and reviews.

Burtis, M.D. [comp.

1995-04-01

410

Phosphinic acid functionalized carbon nanotubes for sensitive and selective sensing of chromium(VI).  

PubMed

Single-walled carbon nanotubes (SWCNTs) have been functionalized with a phosphinic acid derivative 'bis(2,4,4-trimethylpentyl) phosphinic acid' (PA/d). It has been achieved by treating the chlorinated SWCNTs with PA/d at 80°C. Successful functionalization and different nanomaterial properties have been investigated by UV-vis-NIR, FTIR, Raman spectroscopy, AFM and FE-SEM. PA/d conjugated SWCNTs (CNT-PA) are dispersible in some common organic solvents, e.g. CH2Cl2, DMF, CHCl3, and THF. The 'CNT-PA' complex was spin-casted on boron doped silicon wafer. Thus fabricated sensing electrode is demonstrated for sensitive and selective electrochemical sensing of chromium(VI) ions. A linear response is obtained over a wide range of Cr(VI) concentration (0.01-10 ppb). The sensor's sensitivity and the limit of detection are observed to be 35 ± 4 nA/ppb and 0.01 ppb, respectively. The practical utility of the proposed sensor is demonstrated by determining the Cr(VI) concentration in an industrial effluent sample and an underground water sample. PMID:25016454

Deep, Akash; Sharma, Amit L; Tuteja, Satish K; Paul, A K

2014-08-15

411

Ab initio molecular dynamics simulations of aqueous triflic acid confined in carbon nanotubes.  

PubMed

Ab initio molecular dynamics simulations were performed to investigate the effects of nanoscale confinement on the structural and dynamical properties of aqueous triflic acid (CF3SO3H). Single-walled carbon nanotubes (CNTs) with diameters ranging from ?11 to 14 Å were used as confinement vessels, and the inner surface of the CNT were either left bare or fluorinated to probe the influence of the confined environment on structural and dynamical properties of the water and triflic acidic. The systems were simulated at hydration levels of n = 1-3 H2O/CF3SO3H. Proton dissociation expectedly increased with increasing hydration. Along with the level of hydration, hydrogen bond connectivity between the triflic acid molecules, both directly and via a single water molecule, played a role on proton dissociation. Direct hydrogen bonding between the CF3SO3H molecules, most commonly found in the larger bare CNT, also promoted interactions between water molecules allowing for greater separation of the dissociated protons from the CF3SO3(-) as the hydration level was increased. However, this also resulted in a decrease in the overall proportion of dissociated protons. The confinement dimensions altered both the hydrogen bond network and the distribution of water molecules where the H2O in the fluorinated CNTs tended to form small clusters with less proton dissociation at n = 1 and 2 but the highest at n = 3. In the absence of nearby hydrogen bond accepting sites from H2O or triflic acid SO3H groups, the water molecules formed weak hydrogen bonds with the fluorine atoms. In the bare CNT systems, these involved the CF3 groups of triflic acid and were more frequently observed when direct hydrogen bonding between CF3SO3H hindered potential hydrogen bonding sites. In the fluorinated tubes, interactions with the covalently bound fluorine atoms of the CNT wall dominated which appear to stabilize the hydrogen bond network. Increasing the hydration level increased the frequency of the OH···F (CNT) hydrogen bonding which was highly pronounced in the smaller fluorinated CNT indicating an influence on the confinement dimensions on these interactions. PMID:24983213

Clark, Jeffrey K; Habenicht, Bradley F; Paddison, Stephen J

2014-08-21

412

Effects of Temperature and Acidic Pre-Treatment on Fenton-Driven Oxidation of MTBE-Spent Granular Activated Carbon  

EPA Science Inventory

Temperature-dependent mechanisms in the Fenton-driven chemical oxidation of methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was investigated. Prior to iron (Fe) amendment to the GAC, acid-treatment altered the surface chemistry of the GAC and lowered the pH ...

413

Effects on temperature and acidic pre-treatment on Fenton-driven oxidation of MTBE-spent granular activated carbon  

EPA Science Inventory

Temperature-dependent mechanisms in the Fenton-driven chemical oxidation of methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was investigated. Prior to iron (Fe) amendment to the GAC, acid-treatment altered the surface chemistry of the GAC and lowered the p...

414

On the formation of carbonic acid (H2CO3) in solar system ices Weijun Zheng a,b  

E-print Network

]. These species can interact with ices and create cascades of secondary electrons in the track of the implanted are formed in the track of the galactic cosmic ray and solar wind proton implants once they penetrate the ice of possible mechanisms to form carbonic acid could be found [13]; this falls short because 0009-2614/$ - see

Kaiser, Ralf I.

415

Process for purifying gases containing HCN  

Microsoft Academic Search

Gases containing hydrogen cyanide, ammonia and hydrogen sulfide are purified by first washing the gas with a suspension of solid sulfur to fix the hydrogen cyanide as ammonium thiocyanate and ammonium thiosulfate. The resulting suspension is then subjected to a wet-oxidation wherein the thiosulfate and a part of the thiocyanate is converted into sulfuric acid and ammonium sulfate afterwhich the

I. Ooka; N. Tomihisa; Y. Nogami; K. Katagiri

1976-01-01

416

Comparison of driving gases for IABPs.  

PubMed

Several aspects of CO2 vs He as the driving gas in intra-aortic balloon counterpulsation systems were reviewed and investigated. Carbon dioxide seems to be significantly safer than other gases, but not benign. Helium produces a faster balloon response, but the physiologic significance has not been defined. Balloon driving gases become diluted in relatively short time. Leak detection systems have significant limitations. It seems prudent for users of dual-balloon systems to periodically measure the PCO2 of the driving gas. A better method of purging the single-balloon system was developed. PMID:6785559

Kayser, K L; Johnson, W D; Shore, R T

1981-01-01

417

Regulating Greenhouse Gases  

NSDL National Science Digital Library

This video highlights the work of climate scientists in the Amazon who research the relationship between deforestation, construction of new dams, and increased amounts of greenhouse gases being exchanged between the biosphere and the atmosphere.

Kqed; Domain, Teachers'

418

Filter for cleaning hot gases  

SciTech Connect

In an apparatus for cleaning hot gases a filter housing has an inlet for unfiltered gas and an outlet for filtered gas. A plurality of filtered inserts are placed within the housing in a manner capable of filtering undesirable components from the gas feed stream. Each filter insert is made of a fibrous filter material. Silicic-acid glass fibers have a silicic acid content of at least 90%. Coated upon the fibers and absorbed into their pores is a metal oxide of aluminum, titanium, zirconium, cromium, nickle or cobalt. A honeycombed cage filled with high temperature resistant perlite is located within the housing between the gas inlet and the fiber inserts. The cage has an inlet and outlet external to the housing for replacing the perlite. A combustion chamber mounted in the housing has a discharge nozzle located so that the nozzle is directed at the filter inserts. Combusting materials in the chamber causes an explosive backflow of gases through the filter inserts.

Gresch, H.; Holter, H.; Hubner, K.; Igelbuscher, H.; Weber, E.

1981-10-20

419

Effects of carbon and nitrogen sources on fatty acid contents and composition in the green microalga, Chlorella sp. 227.  

PubMed

In order to investigate and generalize the effects of carbon and nitrogen sources on the growth of and lipid production in Chlorella sp. 227, several nutritional combinations consisting of different carbon and nitrogen sources and concentrations were given to the media for cultivation of Chlorella sp. 227, respectively. The growth rate and lipid content were affected largely by concentration rather than by sources. The maximum specific growth was negatively affected by low concentrations of carbon and nitrogen. There is a maximum allowable inorganic carbon concentration (less than 500~1,000 mM bicarbonate) in autotrophic culture, but the maximum lipid content per gram dry cell weight (g DCW) was little affected by the concentration of inorganic carbon within the concentration. The lipid content per g DCW was increased when the microalga was cultured with the addition of glucose and bicarbonate (mixotrophic) at a fixed nitrogen concentration and with the lowest nitrogen concentration (0.2 mM), relatively. Considering that lipid contents per g DCW increased in those conditions, it suggests that a high ratio of carbon to nitrogen in culture media promotes lipid accumulation in the cells. Interestingly, a significant increase of the oleic acid amount to total fatty acids was observed in those conditions. These results showed the possibility to induce lipid production of high quality and content per g DCW by modifying the cultivation conditions. PMID:22031034

Cho, Sunja; Lee, Dukhaeng; Luong, Thao Thanh; Park, Sora; Oh, You-Kwan; Lee, Taeho

2011-10-01

420

Synthesis of biodiesel from a model waste oil feedstock using a carbon-based solid acid catalyst: reaction and separation.  

PubMed

A solid acid catalyst that can keep high activity and stability is necessary when low cost feedstocks are utilized for biodiesel synthesis because the reaction medium contains a large amount of water. Three solid acid catalysts were prepared by the sulfonation of carbonized vegetable oil asphalt and petroleum asphalt. The structure of these catalysts was characterized by a variety of techniques. A new process that used the coupling of the reaction and separation was employed, which greatly improved the conversion of cottonseed oil (triglyceride) and free fatty acids (FFA) when a model waste oil feedstock was used. The vegetable oil asphalt-based catalyst showed the highest catalytic activity. This was due to the high density and stability of its acid sites, its loose irregular network, its hydrophobicity that prevented the hydration of -OH species, and large pores that provided more acid sites for the reactants. PMID:20219353

Shu, Qing; Nawaz, Zeeshan; Gao, Jixian; Liao, Yuhui; Zhang, Qiang; Wang, Dezheng; Wang, Jinfu

2010-07-01

421

Analytical methods for toxic gases from thermal degradation of polymers  

NASA Technical Reports Server (NTRS)

Toxic gases evolved from the thermal oxidative degradation of synthetic or natural polymers in small laboratory chambers or in large scale fire tests are measured by several different analytical methods. Gas detector tubes are used for fast on-site detection of suspect toxic gases. The infrared spectroscopic method is an excellent qualitative and quantitative analysis for some toxic gases. Permanent gases such as carbon monoxide, carbon dioxide, methane and ethylene, can be quantitatively determined by gas chromatography. Highly toxic and corrosive gases such as nitrogen oxides, hydrogen cyanide, hydrogen fluoride, hydrogen chloride and sulfur dioxide should be passed into a scrubbing solution for subsequent analysis by either specific ion electrodes or spectrophotometric methods. Low-concentration toxic organic vapors can be concentrated in a cold trap and then analyzed by gas chromatography and mass spectrometry. The limitations of different methods are discussed.

Hsu, M.-T. S.

1977-01-01

422

Adsorption of atmospheric gases at the air-water interface. 2: C{sub 1}-C{sub 4} alcohols, acids, and acetone  

SciTech Connect

Measurements of the temperature- and concentration-dependent surface tensions of aqueous solutions of methanol, 1- and 2-propanol, 1- and 2-butanol, acetic, propionic, and butanoic acids, and acetone were used to determine the standard free energies, enthalpies, and entropies of adsorption from the vapor phase onto a water surface. The saturated surface coverage of all these species is approximately 10{sup 14} molecules cm{sup {minus}2}. The standard enthalpies of adsorption are correlated to the enthalpies of solution, suggesting that these molecules are partially solvated in the adsorbed state. These results further suggest that atmospheric water droplets could be coated with an organic layer.

Donaldson, D.J.; Anderson, D. [Univ. of Toronto, Ontario (Canada)] [Univ. of Toronto, Ontario (Canada)

1999-02-18

423

Measurement of carbon for carbon sequestration and site monitoring  

SciTech Connect

A 2 to 6 degree C increase in global temperature by 2050 has been predicted due to the production of greenhouse gases that is directly linked to human activities. This has encouraged an increase in the international efforts on ways to reduce anthropogenic emissions of greenhouse gases particularly carbon dioxide (CO{sub 2}) as evidence for the link between atmospheric greenhouse gases and climate change has been established. Suggestion that soils and vegetation could be managed to increase their uptake and storage of CO{sub 2}, and thus become 'land carbon sinks' is an incentive for scientists to undertake the ability to measure and quantify the carbon in soils and vegetation to establish base-line quantities present at this time. The verification of the permanence of these carbon sinks has raised some concern regarding the accuracy of their long-term existence. Out of the total percentage of carbon that is potentially sequestered in the terrestrial land mass, only 25% of that is sequestered above ground and almost 75% is hypothesized to be sequestered underground. Soil is composed of solids, liquids, and gases which is similar to a three-phase system. The gross chemical composition of soil organic carbon (SOC) consists of 65% humic substances that are amorphous, dark-colored, complex, polyelectrolyte-like materials that range in molecular weight from a few hundred to several thousand Daltons. The very complex structure of humic and fulvic acid makes it difficult to obtain a spectral signature for all soils in general. The humic acids of different soils have been observed to have polymeric structure, appearing as rings, chains and clusters as seen in electron microscope observations. The humification processes of the soils will decide the sizes of their macromolecules that range from 60-500 angstroms. The percentage of the humus that occurs in the light brown soils is much lower than the humus present in dark brown soils. The humus of forest soils is characterized by a high content of fulvic acids while the humus of peat and grassland soils is high in humic acids. Similarly it is well known that the amount of carbon present in forest soils is lower than the amount present in grassland soils.

Martin, Madhavi Z [ORNL; Wullschleger, Stan D [ORNL; Garten Jr, Charles T [ORNL; Palumbo, Anthony Vito [ORNL

2007-01-01

424

Surface characteristics and electrochemical capacitances of carbon aerogels obtained from resorcinol and pyrocatechol using boric and oxalic acids as polymerization catalysts  

Microsoft Academic Search

Carbon aerogels were prepared by carbonizing (at 500–1500°C) organic aerogels obtained from the polymerization reaction of resorcinol and\\/or pyrocatechol with formaldehyde using boric and oxalic acids as polymerization catalysts. Prepared samples were characterized by different techniques to ascertain their composition, surface chemistry, morphology, and surface physics, determining their electrochemical capacitances in acidic medium. The use of pyrocatechol yielded carbon aerogels

Carlos Moreno-Castilla; Marta B. Dawidziuk; Francisco Carrasco-Marín; Zulamita Zapata-Benabithe

2011-01-01

425

Hydrogen, Oxygen, and Carbon Isotope Ratios of Cellulose from Submerged Aquatic Crassulacean Acid Metabolism and Non-Crassulacean Acid Metabolism Plants  

PubMed Central

Isotope ratios of cellulose and cellulose nitrate from aquatic Crassulacean acid metabolism (CAM) and non-CAM plants were determined. Cellulose oxygen istope ratios for all plants that grew together were virtually identical, whereas large differences were observed for hydrogen isotope ratios of cellulose nitrate between CAM and non-CAM plants. Carbon isotope ratios of cellulose nitrate did not differentiate CAM from non-CAM plants. PMID:16663824

Sternberg, Leonel; Deniro, Michael J.; Keeley, Jon E.

1984-01-01

426

Succinic acid production with reduced by-product formation in the fermentation ofAnaerobiospirillum succiniciproducens using glycerol as a carbon source  

Microsoft Academic Search

Succinic acid was produced by fermentation of Anaerobiospirillum succiniciproducens using glycerol as a carbon source. When cells were anaerobically cultured in a medium containing 6.5 g\\/L glycerol, a high succinic acid yield (133%) was obtained while avoiding the for- mation of by-product acetic acid. The gram ratio of suc- cinic acid to acetic acid was 25.8:1, which is 6.5 times

Pyung Cheon Lee; Woo Gi Lee; Sang Yup Lee; Ho Nam Chang

2001-01-01

427

Synthesis and characterization of sulfonated single-walled carbon nanotubes and their performance as solid acid catalyst  

SciTech Connect

Single-walled carbon nanotubes (SWCNTs) were treated with sulfuric acid at 300 deg. C to synthesize sulfonated SWCNTs (s-SWCNTs), which were characterized by electron microscopy, infrared, Raman and X-ray photoelectron spectroscopy, and thermo analysis. Compared with activated carbon, more sulfonic acid groups can be introduced onto the surfaces of SWCNTs. The high degree ({approx}20 wt%) of surface sulfonation led to hydrophilic sidewalls that allows the SWCNTs to be uniformly dispersed in water and organic solvents. The high surface acidity of s-SWCNTs was demonstrated by NH{sub 3} temperature-programmed desorption technique and tested by an acetic acid esterification reaction catalyzed by s-SWCNTs. The results show that the water-dispersive s-SWCNTs are an excellent solid acid catalyst and demonstrate the potential of SWCNTs in catalysis applications. - Graphical abstract: Sulfonated SWCNTs with 20 wt% -SO{sub 2}OH groups were prepared by a high-temperature H{sub 2}SO{sub 4} process, which transformed the hydrophobic surface of pristine SWCNTs to a hydrophilic surface and provided an excellent performance as solid acid catalyst.

Yu Hao [School of Chemical and Energy Engineering, South China University of Technology, Guangzhou 510641 (China)], E-mail: yuhao@scut.edu.cn; Jin Yuguang; Li Zhili [School of Chemical and Energy Engineering, South China University of Technology, Guangzhou 510641 (China); Peng Feng [School of Chemical and Energy Engineering, South China University of Technology, Guangzhou 510641 (China)], E-mail: cefpeng@scut.edu.cn; Wang Hongjuan [School of Chemical and Energy Engineering, South China University of Technology, Guangzhou 510641 (China)

2008-03-15

428

Influence of acid functionalization on the cardio-pulmonary toxicity of carbon nanotubes and carbon black in mice  

EPA Science Inventory

Engineered carbon nanotubes are being developed for a wide range of industrial and medical applications. Because of their unique properties, nanotubes can impose potentially toxic effects, particularly if they have been mod