Note: This page contains sample records for the topic acid gases carbon from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Removal of acidic gases from gaseous mixtures  

Microsoft Academic Search

A British improvement of a process for removing acidic gases (such as carbon dioxide and hydrogen sulfide) from gaseous mixtures in a 2-step MEA or DEA arrangement maintains substantially constant concentrations of the volatile reagent in the regenerated solutions entering the 1st and 2nd absorption zones, controls the flow of stripping steam to each regeneration zone (minimizing the flow to

Thirkell

1973-01-01

2

Adsorption of gases in carbon nanotubes  

Microsoft Academic Search

This work addresses the physical adsorption of gases in carbon nanotubes. In the confining environment of nanotube bundles, adsorbed atoms exhibit behavior characteristic of 1, 2, and 3 dimensions as a function of thermodynamic parameters, geometry, and microscopic variables. Many body interactions among quasi-1D phases of gases adsorbed within carbon nanotubes and the corresponding implications for condensation transition are investigated.

Milen Kalushkov Kostov

2003-01-01

3

New solvent purifies crude (and) coal acid gases  

Microsoft Academic Search

Allied Chemical Corp. has developed a new solvent process using the dimethyl ether of polyethylene glycol (called Selexol) for the selective absorption of sulfur gases and the bulk removal of acid gases in gasification plants fed with heavy crude oil or coal. The solvent has very different absorption characteristics for carbonyl sulfide, hydrogen sulfide, carbon dioxide, ammonia, and hydrocarbons. Commercial

Valentine

1974-01-01

4

Method of producing pyrolysis gases from carbon-containing materials  

Microsoft Academic Search

This patent describes a method for producing pyrolysis gases from carbon-containing materials. The method comprising: pyrolyzing the carbon-containing materials in a gasification reactor in order to form pyrolysis gases therefrom. The pyrolysis gases having residual tar and oil byproducts entrained therein; passing the pyrolysis gases from the gasification reactor into and through a catalytic reactor having a fluidized bed therein

L. K. Mudge; M. D. Brown; W. A. Wilcox; E. G. Baker

1989-01-01

5

Removal of acid gases in dry scrubbing of hot gases  

SciTech Connect

This patent describes a method for the removal of sulfur oxide gases from a flue gas containing the same. The method comprising: dispersing finely-divided dry hydrated lime in a humid inert gas having a relative water vapor pressure higher than the fugacity of at least a monomolecular layer of water thereby adsorbed on the hydrated lime; bringing the dispersed hydrated lime and adsorbed water into contact with gaseous carbon dioxide thereby converting surfaces of the lime to calcium carbonate; flowing the dispersion of so-carbonated lime into admixture and reactive contact with the fluid gas to form calcium sulfite and sulfates from sulfur oxides in the flue gas; subsequently removing solids including reacted calcium sulfite and sulfate and excess reactants from the so-treated flue gas and discharging so-purified flue gas to the atmosphere.

Lerner, B.J.

1989-09-12

6

Carbonate acidizing  

SciTech Connect

The authors present the first quantitative study and complete model of the wormholing phenomenon, leading to a means of predicting and optimizing carbonate acidizing treatments. Laboratory experiments on a gypsum model system and computer simulations show that for a given geometry, wormholes can be quantified by a unique parameter, their equivalent hydraulic length. The behavior of this quantifying parameter vs. all the system parameters is studied and allows the quantitative prediction of the efficiency of an acidizing treatment. This study highlights the fractal nature of the phenomenon, which is accounted for in the equations, and the strong effect of the sample geometry. Three types of etching can be obtained: compact, wormhole type, or homogeneous. The optimum conditions for achieving the best skin decrease correspond to the creation of wormholes and can then be defined in terms of fluid reactivity and injection rate.

Daccord, G.; Touboul, E.; Lenormand, R.

1989-02-01

7

Method of producing pyrolysis gases from carbon-containing materials  

Microsoft Academic Search

A gasification process of improved efficiency is disclosed. A dual bed reactor system is used in which carbon-containing feedstock materials are first treated in a gasification reactor to form pyrolysis gases. The pyrolysis gases are then directed into a catalytic reactor for the destruction of residual tars\\/oils in the gases. Temperatures are maintained within the catalytic reactor at a level

Lyle K. Mudge; Michael D. Brown; Wayne A. Wilcox; Eddie G. Baker

1989-01-01

8

The Origin of Some Natural Carbon Dioxide Gases  

Microsoft Academic Search

Natural carbon dioxide gas issues from vents and springs in sedimentary rocks. Exploratory wells drilled for oil have produced large volumes of carbon dioxide in subsurface. Where these gases are found in quantity, limestones and igneous rocks are in close association and the origin of the gases is thus suggested. Until the advent of the mass spectrometer there was no

Walter B. Lang

1959-01-01

9

Clostridium strain which produces acetic acid from waste gases  

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. 4 figs.

Gaddy, J.L.

1997-01-14

10

Removal of acid gases in dry scrubbing of hot gases  

Microsoft Academic Search

This patent describes a method for the removal of sulfur oxide gases from a flue gas containing the same. The method comprising: dispersing finely-divided dry hydrated lime in a humid inert gas having a relative water vapor pressure higher than the fugacity of at least a monomolecular layer of water thereby adsorbed on the hydrated lime; bringing the dispersed hydrated

1989-01-01

11

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 and 100 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 environmentally acceptable levels. Urea or sulfamic acid are preferred, especially sulfamic acid, and step (C) is not necessary or performed. 16 figs.

Chang, S.G.

1994-09-20

12

Processes to remove acid forming gases from exhaust gases  

SciTech Connect

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

13

Method of removing carbon monoxide from gases  

DOEpatents

A process and catalyst are disclosed for purifying an atmosphere containing carbon monoxide by passing the atmosphere through a bed of a catalyst of TbO.sub.x, where x = 1.8 to 1.5, which oxidizes the carbon monoxide to carbon dioxide.

Gerstein, Bernard C. (Ames, IA); Macaulay, David B. (Arlington Heights, IL)

1976-06-01

14

21 CFR 201.161 - Carbon dioxide and certain other gases.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Carbon dioxide and certain other gases. 201.161...LABELING Other Exemptions § 201.161 Carbon dioxide and certain other gases. (a) Carbon dioxide, cyclopropane, ethylene,...

2013-04-01

15

A MODEL FOR THE DISTRIBUTION OF ACID GASES BETWEEN AN AQUEOUS ALKANOLAMINE SOLUTION AND LPG  

Microsoft Academic Search

The model of Deshmukh and Mather (1981) is a popular method for correlating and predicting the vapor-liquid equilibria in systems containing acid gases (hydrogen sulfide and carbon dioxide) and aqueous solutions of alkanolamines. The model includes phase equilibrium between an aqueous liquid and a gas as well as chemical equilibrium in the aqueous phase. A recent review by Weiland et

J. J. CARROLL; A. E. MATHER

1996-01-01

16

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.

Wei, C. T.; Mironova, P. V.; Fortgh, J.; Schleich, W. P.; Walser, R.

2013-10-01

17

Process for removal of carbonyl sulfide in liquified hydrocarbon gases with absorption of acid gases  

Microsoft Academic Search

Liquified hydrocarbon gases containing at least carbonyl sulfide as an impurity are purified by intimately mixing the liquified hydrocarbon gas with an aqueous absorbent for hydrogen sulfide in a hydrolysis zone maintained at a temperature and a pressure sufficient to maintain the liquified hydrocarbon gas in the liquid state and hydrolyze the carbonyl sulfide to hydrogen sulfide and carbon dioxide.

D. K. Beavon; M. Mackles

1980-01-01

18

Long-range transport of ozone, carbon monoxide, and acidic trace gases at Oki Island, Japan, during PEM-WEST B/PEACAMPOT B campaign  

NASA Astrophysics Data System (ADS)

Ground based measurements of ozone, CO, HNO3 SO2, HCl, and formic acid were carried out at Oki, a remote island site in the Sea of Japan, during Feburuary 26 to March 16, 1994, as the Pacific Exploratory Mission in the Western Pacific/Perturbation by East Asian Continental Air Mass to the Pacific Oceanic Troposphere (PEM-West B/PEACAMPOT B) campaign. According to trajectory analysis, the air mass reaching Oki was classified into four groups: northerly, northwesterly, west-northwesterly, and westerly flows. Clear dependence of gas concentrations on flow direction of air mass was found for all species studied. Lowest concentrations were observed in the northerly airflow originating from the Bering Sea. The mean concentrations of ozone and CO in northerly flow were 37.61.9 and 1511 ppbv, respectively. The mean values of HNO3, SO2, HCl, and formic acid in the northerly flow were 3410, 415, 10723, and 5481 pptv, respectively. The highest concentrations of all species were observed in the westerly flow passing through a lower boundary layer over the Yellow Sea and South Korean Peninsula. The mean concentrations of ozone and CO in the westerly flow were 45.94.0 and 29244 ppbv, respectively. The mean values of HNO3, SO2, HCl, and formic acid in the westerly flow were 13737, 20751307, 515214, and 264183 pptv, respectively. Clear seasonal variation of the "background" concentrations of ozone and CO were identified by comparison with the data from the PEM-West A/PEACAMPOT A campaign conducted in the fall. In contrast to other species, strong diurnal variation of formic acid with a daytime maximum was observed. The possibility of photochemical formation of formic acid from HCHO and the HO2 radical is discussed.

Kajii, Yoshizumi; Akimoto, Hajime; Komazaki, Yuichi; Tanaka, Shigeru; Mukai, Hitoshi; Murano, Kentaro; Merrill, John T.

1997-12-01

19

Understanding blood gases\\/acidbase balance  

Microsoft Academic Search

Acidbase balance is regulated by intracellular & extracellular buffers and by the renal and respiratory systems. Normal pH is necessary for the optimal function of cellular enzymes and metabolism. Disorders of acidbase balance can interfere with these physiological mechanisms leading to acidosis or alkalosis and can be potentially life threatening. Blood gas analysis is a routine procedure performed in the

Nitin Goel; Jennifer Calvert

20

Process for removing acidic gases from gaseous mixtures using aqueous scrubbing solutions containing heterocyclic nitrogen compounds  

SciTech Connect

A process is described for removing acid gases selected from hydrogen sulfide and carbon dioxide from gaseous feeds. The process comprises: contacting the feed with an aqueous scrubbing solution comprising water and 1 to 11 moles of a heterocyclic nitrogen compound per liter of solution which compound is selected from the group consisting of imidazole, a C/sub 1/-C/sub 3/ alkyl-substituted imidazole where the alkyl groups are bonded to at least one carbon atom, and a C/sub 1/-C/sub 3/ alkyl- or C/sub 1/-C/sub 3/ hydroxayalkyl-substituted piperazine where the alkyl or hydrozyalkyl groups are bonded to both nitrogen atoms of the ring. The compound has a pKa no greater than about 8, at conditions whereby acid gases are absorbed by the scrubbing solution.

Pan, Y.C.; Savage, D.W.

1986-11-25

21

Prediction of water content of sour and acid gases  

Microsoft Academic Search

Estimating the feasibility of acid gas geological disposal requires the knowledge of the water content of the gas phase at moderate pressures and temperatures (typically below 50MPa, below 380K) and up to 6mol NaCl. In this paper, a non-iterative model is developed to predict the water content of sour and acid gases at equilibrium with pure water and brine. This

Mohsen Zirrahi; Reza Azin; Hassan Hassanzadeh; Mahmood Moshfeghian

2010-01-01

22

Process for removal of carbonyl sulfide in liquified hydrocarbon gases with absorption of acid gases  

SciTech Connect

Liquified hydrocarbon gases containing at least carbonyl sulfide as an impurity are purified by intimately mixing the liquified hydrocarbon gas with an aqueous absorbent for hydrogen sulfide in a hydrolysis zone maintained at a temperature and a pressure sufficient to maintain the liquified hydrocarbon gas in the liquid state and hydrolyze the carbonyl sulfide to hydrogen sulfide and carbon dioxide. The liquified hydrocarbon gas containing at least a portion of the formed carbonyl sulfide and carbon dioxide is separated from the liquid absorbent and passed to an absorption zone where it is contacted with a liquid hydrogen sulfide absorbent where at least the formed hydrogen sulfide is separated from the liquified petroleum gas. A stage of absorption of at least hydrogen sulfide may proceed mixing of the liquified hydrocarbon gas with the absorbent in the hydrolysis reaction zone. The absorbent employed does not combine irreversibly with carbonyl sulfide, hydrogen sulfide, and carbon dioxide, and preferably is an aqueous solution of diethanolamine.

Beavon, D.K.; Mackles, M.

1980-11-11

23

Mass culture of algae using carbon dioxide from stack gases  

SciTech Connect

Algae are capable of converting CO{sub 2} into organic carbon via photosynthesis, and the efficiency with which this conversion is elected in dense algal cultures exceeds the photosynthetic of any terrestrial crop. It therefore seems reasonable to ask whether dense algal cultures could be used to strip all or part of the CO{sub 2} from power plant stack gases. A system designed to accomplish this task would require dissolving the CO{sub 2} from the stack gases in water and then growing the algae in the carbonated water. One of the principal factors limiting the practical application of this technology is the amount of land area which must be devoted to the collection of solar energy in order to effect the conversion of CO{sub 2} into organic matter. Collection of sunlight over an area of roughly 100 km{sup 2} (38.6 mi{sup 2}) would be required to convert all the CO{sub 2} from a typical 500 MW power plant into organic matter. The goal of this project was to provide information needed to determine whether such a system would be a practical way to control Co{sub 2} emissions from power plants. 23 refs., 18 figs., 15 tabs.

Laws, E. (Hawaii Univ., Honolulu, HI (USA). Office of Research Administration)

1990-10-01

24

Impacts of acid gases on mercury oxidation across SCR catalyst  

Microsoft Academic Search

A series of bench-scale experiments were completed to evaluate acid gases of HCl, SO2, and SO3 on mercury oxidation across a commercial selective catalytic reduction (SCR) catalyst. The SCR catalyst was placed in a simulated flue gas stream containing O2, CO2, H2O, NO, NO2, and NH3, and N2. HCl, SO2, and SO3 were added to the gas stream either separately

Ye Zhuang; Jason Laumb; Richard Liggett; Mike Holmes; John Pavlish

2007-01-01

25

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

26

Coal Derived Fuel Gases for Molten Carbonate Fuel Cells.  

National Technical Information Service (NTIS)

This report characterizes product streams from state-of-the-art and future coal gasification systems to guide fuel cell program planners and researchers in establishing performance goals and developing materials that will be compatible with product gases....

1979-01-01

27

Hydrocarbon gases produced during in vitro peroxidation of polyunsaturated fatty acids and decomposition of preformed hydroperoxides  

Microsoft Academic Search

Hydrocarbon gases have been used previously as an index of lipid peroxidation in vivo and in vitro. In vitro experiments are\\u000a reported on the formation of hydrocarbon gases from peroxidizing ?-3 and ?-6 fatty acids. Hydrocarbon gases were not related\\u000a during a 20-hr peroxidation phase but were released following the decomposition of hydroperoxides by addition of excess ascorbic\\u000a acid. The

Erich E. Dumelin; Al L. Tappel

1977-01-01

28

Carbonic Acid Pretreatment of Biomass  

SciTech Connect

This project sought to address six objectives, outlined below. The objectives were met through the completion of ten tasks. 1) Solidify the theoretical understanding of the binary CO2/H2O system at reaction temperatures and pressures. The thermodynamics of pH prediction have been improved to include a more rigorous treatment of non-ideal gas phases. However it was found that experimental attempts to confirm theoretical pH predictions were still off by a factor of about 1.8 pH units. Arrhenius experiments were carried out and the activation energy for carbonic acid appears to be substantially similar to sulfuric acid. Titration experiments have not yet confirmed or quantified the buffering or acid suppression effects of carbonic acid on biomass. 2) Modify the carbonic acid pretreatment severity function to include the effect of endogenous acid formation and carbonate buffering, if necessary. It was found that the existing severity functions serve adequately to account for endogenous acid production and carbonate effects. 3) Quantify the production of soluble carbohydrates at different reaction conditions and severity. Results show that carbonic acid has little effect on increasing soluble carbohydrate concentrations for pretreated aspen wood, compared to pretreatment with water alone. This appears to be connected to the release of endogenous acids by the substrate. A less acidic substrate such as corn stover would derive benefit from the use of carbonic acid. 4) Quantify the production of microbial inhibitors at selected reaction conditions and severity. It was found that the release of inhibitors was correlated to reaction severity and that carbonic acid did not appear to increase or decrease inhibition compared to pretreatment with water alone. 5) Assess the reactivity to enzymatic hydrolysis of material pretreated at selected reaction conditions and severity. Enzymatic hydrolysis rates increased with severity, but no advantage was detected for the use of carbonic acid compared to water alone. 6) Determine optimal conditions for carbonic acid pretreatment of aspen wood. Optimal severities appeared to be in the mid range tested. ASPEN-Plus modeling and economic analysis of the process indicate that the process could be cost competitive with sulfuric acid if the concentration of solids in the pretreatment is maintained very high (~50%). Lower solids concentrations result in larger reactors that become expensive to construct for high pressure applications.

G. Peter van Walsum; Kemantha Jayawardhana; Damon Yourchisin; Robert McWilliams; Vanessa Castleberry

2003-05-31

29

Carbonic Acid Retreatment of Biomass  

SciTech Connect

This project sought to address six objectives, outlined below. The objectives were met through the completion of ten tasks. (1) Solidify the theoretical understanding of the binary CO{sub 2}/H{sub 2}O system at reaction temperatures and pressures. The thermodynamics of pH prediction have been improved to include a more rigorous treatment of non-ideal gas phases. However it was found that experimental attempts to confirm theoretical pH predictions were still off by a factor of about 1.8 pH units. Arrhenius experiments were carried out and the activation energy for carbonic acid appears to be substantially similar to sulfuric acid. Titration experiments have not yet confirmed or quantified the buffering or acid suppression effects of carbonic acid on biomass. (2) Modify the carbonic acid pretreatment severity function to include the effect of endogenous acid formation and carbonate buffering, if necessary. It was found that the existing severity functions serve adequately to account for endogenous acid production and carbonate effects. (3) Quantify the production of soluble carbohydrates at different reaction conditions and severity. Results show that carbonic acid has little effect on increasing soluble carbohydrate concentrations for pretreated aspen wood, compared to pretreatment with water alone. This appears to be connected to the release of endogenous acids by the substrate. A less acidic substrate such as corn stover would derive benefit from the use of carbonic acid. (4) Quantify the production of microbial inhibitors at selected reaction conditions and severity. It was found that the release of inhibitors was correlated to reaction severity and that carbonic acid did not appear to increase or decrease inhibition compared to pretreatment with water alone. (5) Assess the reactivity to enzymatic hydrolysis of material pretreated at selected reaction conditions and severity. Enzymatic hydrolysis rates increased with severity, but no advantage was detected for the use of carbonic acid compared to water alone. (6) Determine optimal conditions for carbonic acid pretreatment of aspen wood. Optimal severities appeared to be in the mid range tested. ASPEN-Plus modeling and economic analysis of the process indicate that the process could be cost competitive with sulfuric acid if the concentration of solids in the pretreatment is maintained very high ({approx}50%). Lower solids concentrations result in larger reactors that become expensive to construct for high pressure applications.

Baylor university

2003-06-01

30

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

Code of Federal Regulations, 2013 CFR

...for municipal waste combustor acid gases. 60.54a Section...for municipal waste combustor acid gases. (a)-(b) [Reserved...corrected to 7 percent oxygen (dry basis), whichever is less stringent...corrected to 7 percent oxygen (dry basis), whichever is less...

2013-07-01

31

Insights into deep carbon derived from noble gases  

Microsoft Academic Search

Science and society are faced with two challenges that are inextricably linked: fossil-fuel energy dependence and rising levels of atmospheric carbon dioxide. Management of remaining hydrocarbon resources, the search for cleaner fuels and increasing interest in subsurface carbon storage all require a better understanding of the deep terrestrial carbon cycle. The coupling of noble gas and carbon chemistry provides an

B. Sherwood Lollar; C. J. Ballentine

2009-01-01

32

Environmental effects of carbon dioxide and other trace gases  

Microsoft Academic Search

Concern is increasing that certain societal activities may result in a rise in global temperature. Specifically, the increasing accumulation of certain gases in the atmosphere, in part as a result of industrialization, may serve as a blanket over the earth, retaining heat which otherwise would dissipate into space. As a result, global surface and air temperatures could increase to the

Perhac

1988-01-01

33

Helium, Argon, and Carbon in Some Natural Gases  

Microsoft Academic Search

Thirty-nine samples of natural gases representing varied chemical compositions and geological occurrences were analyzed for their helium, radiogenic argon, and atmospheric argon contents. The total range in the (He\\/A)rd ratio was found to be 1.6 to 130 with most samples having values between 6 and 25. This range of values is essentially equal to the production ratio from the uranium,

R. E. Zartman; G. J. Wasserburg; J. H. Reynolds

1961-01-01

34

Catalytic process for removing SO from sulfuric acid plant off gases  

Microsoft Academic Search

The invention is directed to an integrated process for reducing the SO content of sulfuric acid plant off gases by (1) passing the SO-containing feed gas to the process over a specially defined multistage oxidation catalyst to convert SO to SO, (2) absorbing the SO in water to form HSO and (3) scrubbing the off gases with aqueous hydrogen peroxide

1976-01-01

35

Molecular Beam Studies of Reactions Between Stratospheric Gases and Supercooled Sulfuric Acid.  

National Technical Information Service (NTIS)

Sulfuric acid aerosols in the stratosphere contribute to the destruction of the ozone layer by converting inactive gases like HCl and HBr into molecules that fall apart into chlorine and bromine atoms, which catalytically destroy ozone. The first step in ...

G. M. Nathanson J. R. Morris P. M. Behr J. Splan S. Glass

2002-01-01

36

Molecular Beam Studies of Reactions between Stratospheric Gases and Supercooled Sulfuric Acid.  

National Technical Information Service (NTIS)

Sulfuric acid aerosols in the stratosphere contribute to the destruction of the ozone layer by converting inactive gases like HCl and HBr into molecules that fall apart into chlorine and bromine atoms, which catalytically destroy ozone. The first step in ...

G. M. Nathanson J. R. Morris P. M. Behr M. D. Antman J. Splan

2000-01-01

37

Catalytic removal of carbon monoxide from gases at low temperatures  

SciTech Connect

A study was made of the low-temperature oxidation of carbon monoxide using both heavy catalysts (manganese oxide, manganese-palladium, manganese-silver, hopcalite), and catalysts deposited onto mordenite (manganese oxide, cobalt oxide, palladium). It was found that when carbon monoxide reacted with atmospheric oxygen at room temperature the cobalt oxide and palladium catalysts deposited on mordenite were considerably more active than hopcalite, even in the presence of water vapor. By introducing small quantities of ozone into the gaseous reaction mixture it was possible to intensify the carbon monoxide oxidation process with these catalysts.

Solov`ev, S.A.; Belokleitseva, G.M.; Vlasenko, V.M.

1993-02-20

38

Carbon dioxide capture from combustion flue gases with a calcium oxide chemical loop. Experimental results and process development  

Microsoft Academic Search

Post-combustion carbonate looping processes are based on the capture of carbon dioxide from the flue gases of an existing power plant in a circulating fluidized bed reactor (CFB) of calcium oxide (the carbonator) particles. The calcination of calcium carbonate in a new oxy-fired CFBC power plant regenerates the sorbent (calcium oxide particles) and obtains high purity carbon dioxide. This communication

M. Alonso; N. Rodrguez; B. Gonzlez; G. Grasa; R. Murillo; J. C. Abanades

2010-01-01

39

The CNG process: Acid gas removal with liquid carbon dioxide  

SciTech Connect

The CNG acid gas removal process has two unique features: the absorption of sulfur-containing compounds and other trace contaminants with liquid carbon dioxide, and the regeneration of pure liquid carbon dioxide by triple-point crystallization. The process is especially suitable for treating gases which contain large amounts of carbon dioxide and much smaller amounts (relative to carbon dioxide) of hydrogen sulfide. Capital and energy costs are lower than conventional solvent processes. Further, products of the CNG process meet stringent purity specifications without undue cost penalties. A process demonstration unit has been constructed and operated to demonstrate the two key steps of the CNG process. Hydrogen sulfide and carbonyl sulfide removal from gas streams with liquid carbon dioxide absorbent to sub-ppm concentrations has been demonstrated. The production of highly purified liquid carbon dioxide (less than 0.1 ppm total contaminant) by triple-point crystallization also has been demonstrated.

Liu, Y.C.; Auyang, L.; Brown, W.R.

1987-01-01

40

Coal Derived Fuel Gases for Molten Carbonate Fuel Cells.  

National Technical Information Service (NTIS)

Product streams from state-of-the-art and future coal gasification systems are characterized to guide fuel cell program planners and researchers in establishing performance goals and developing materials for molten carbonate fuel cells that will be compat...

1979-01-01

41

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 earths 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

42

Combustion vs. Pyrolysis of Presolar Diamonds: Association of P3 and HL Noble Gases with Carbon  

Microsoft Academic Search

Since it became clear that presolar diamonds are not identical and perhaps consist of several carriers of isotopically anomalous (like HL-Xe and light nitrogen) and isotopically normal (carbon and P3 noble gases) components, it is important to know how these components are related to the diamond carriers. Because of diamond grains are too small to be analyzed individually and the

A. B. Verchovsky; A. V. Fisenko; C. T. Pillinger

1995-01-01

43

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

44

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

45

Some Physical Properties of Compressed Gases. II, Carbon Monoxide  

Microsoft Academic Search

The writers have adjusted and extrapolated the compressibility data obtained by Bartlett and his collaborators on carbon monoxide, so that accurate p-v-T relations from -70 to 400 and up to 1200 atm. are available. The relatively low pressure isotherms of Scott at 25 and of Goig-Botella at 0, 12.44, and 20.22 are included. Derivatives are obtained by the graphical scheme

W. Edwards Deming; Lola E. Shupe

1931-01-01

46

Spark combustion reactor for 13-carbon isotope enrichment analysis of gases  

NASA Astrophysics Data System (ADS)

A novel spark combustion reactor was designed, built, and utilized for quantitative 13-carbon isotope determination of highly enriched permanent gases. The analytical methodology developed is straightforward and begins by loading the reactor with hydrocarbon and oxygen using a steel gas manifold. High voltage is applied to the platinum electrode spark plug incorporated into the reactor, which rapidly converts hydrocarbon to carbon dioxide (and other products). Carbon dioxide species are then quantitated by quadrupole mass spectrometry. The primary reactor consists of a three-way stainless steel tee, plus the following components connected to threaded ports: (1) a platinum electrode spark plug sealed with a Viton O ring, (2) a steel gas storage cylinder, and (3) a manual bellows valve terminated with a VCO type connector. Making use of the spark combustion reactor, the 13-carbon fraction of highly enriched 13CH4 was measured to be >=99.5 at. % 13C. This portable, static reactor permits determination of the 13C/12C isotope fraction for permanent gases utilizing mass spectrometric detection. The analytical system presented is relatively rapid (due to spark ignition), straightforward, and flexible (applicable to hydrocarbon gases using various gas detectors). Its limitation in performance for 13C isotope work is probably due to carbon embedded in the reactor interior.

May, Michael; Gray, Michael; Kuo, John E.; Tan, C. T.

2003-04-01

47

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 Astrophysics Data System (ADS)

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.

1982-06-01

48

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

49

Flame Synthesis of Carbon Nanotubes Using Low Calorific Value Gases  

SciTech Connect

Nanostructures formed in diffusion flames of pure fuels [CH{sub 4}, C{sub 3}H{sub 8}, and C{sub 2}H{sub 2}] at different fuel flow rates have been analyzed. Synthesis samples have been also collected from diffusion flames of various fuel blends [H{sub 2}-CH{sub 4}, H{sub 2}-CO, H{sub 2}-C{sub 3}H{sub 8}, H{sub 2}-C{sub 2}H{sub 2}] at different combustion conditions. SEM images of particulate samples collected from H{sub 2}-CH{sub 4} diffusion flames show formation of nanostructures. However, the formation of nanostructures only occurs at a narrow window of fuel compositions (< 10% H{sub 2} concentration in the mixture) and flow conditions (Jet Exit Reynolds number Re{sub j} = 200). At higher H{sub 2} concentration and flow velocity, formation of nanostructures diminishes and H{sub 2}-CH{sub 4} flames produce amorphous carbon and soot particles.

Jorge Camacho; Mahesh Subramanya; Ahsan R. Choudhuri

2007-03-31

50

Process for the removal of acid gases from gaseous streams  

SciTech Connect

Hydrogen sulfide, carbon dioxide, and carbonyl sulfide are removed from a gas stream in a staged procedure by: absorption of the CO/sub 2/ and COS; conversion of the hydrogen sulfide to produce sulfur in an absorbent mixture; hydrolysis of the carbonyl sulfide to produce a gas stream of hydrogen sulfide and carbon dioxide; and removal of the hydrogen sulfide from the gas stream.

Blytas, G.C.; Diaz, Z.

1982-11-16

51

The Amount, Molecular Distribution and Stable Carbon Isotopic Composition of Individual Hydrocarbon Gases from the Gulf of Cadiz, NE Atlantic  

Microsoft Academic Search

Investigations of molecular and carbon isotopic variability of hydrocarbon gases (C1-C5) along sedimentary sections were performed on a number of mud volcanoes from fluid venting provinces located in the Gulf of Cadiz, NE Atlantic. Hydrocarbon gases were collected during Training Through Research Cruises (TTR) in 1999 (TTR9) and in 2000 (TTR10). This study focused primarily on the allochthonous hydrocarbon gases

A. Stadnitskaia; M. Ivanov; T. van Weering; V. Blinova

2003-01-01

52

Analysis of effluent gases during the CCVD growth of multi-wall carbon nanotubes from acetylene  

Microsoft Academic Search

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

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

2006-01-01

53

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

54

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

55

Carbon dioxide sequestration by direct mineral carbonation with carbonic acid  

SciTech Connect

The Albany Research Center (ARC) of the U.S. Dept. of Energy (DOE) has been conducting a series of mineral carbonation tests at its Albany, Oregon, facility over the past 2 years as part of a Mineral Carbonation Study Program within the DOE. Other participants in this Program include the Los Alamos National Laboratory, Arizona State University, Science Applications International Corporation, and the DOE National Energy Technology Laboratory. The ARC tests have focused on ex-situ mineral carbonation in an aqueous system. The process developed at ARC utilizes a slurry of water mixed with a magnesium silicate mineral, olivine [forsterite end member (Mg2SiO4)], or serpentine [Mg3Si2O5(OH)4]. This slurry is reacted with supercritical carbon dioxide (CO2) to produce magnesite (MgCO3). The CO2 is dissolved in water to form carbonic acid (H2CO3), which dissociates to H+ and HCO3 -. The H+ reacts with the mineral, liberating Mg2+ cations which react with the bicarbonate to form the solid carbonate. The process is designed to simulate the natural serpentinization reaction of ultramafic minerals, and for this reason, these results may also be applicable to in-situ geological sequestration regimes. Results of the baseline tests, conducted on ground products of the natural minerals, have been encouraging. Tests conducted at ambient temperature (22 C) and subcritical CO2 pressures (below 73 atm) resulted in very slow conversion to the carbonate. However, when elevated temperatures and pressures are utilized, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant reaction occurs within much shorter reaction times. Extent of reaction, as measured by the stoichiometric conversion of the silicate mineral (olivine) to the carbonate, is roughly 90% within 24 hours, using distilled water, and a reaction temperature of 185?C and a partial pressure of CO2 (PCO2) of 115 atm. Recent tests using a bicarbonate solution, under identical reaction conditions, have achieved roughly 83% conversion of heat treated serpentine and 84% conversion of olivine to the carbonate in 6 hours. The results from the current studies suggest that reaction kinetics can be improved by pretreatment of the mineral, catalysis of the reaction, or some combination of the two. Future tests are intended to examine a broader pressure/temperature regime, various pretreatment options, as well as other mineral groups.

O'Connor, William K.; Dahlin, David C.; Nilsen, David N.; Walters, Richard P.; Turner, Paul C.

2000-01-01

56

Modelling and simulation of condensation phenomena of acid gases in an industrial chimney  

Microsoft Academic Search

Coal power stations as well as waste incinerators produce humid acid gases which condensate in industrial chimneys. These condensates may cause corrosion of the internal cladding made of stainless steels, nickel base alloys or non metallic materials. In the aim of polluting emission reduction and material optimal choice, it is necessary to determine all the phenomena which occur throughout the

SERRIS Eric; COURNIL Michel; PEULTIER Jrme

57

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

58

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

Code of Federal Regulations, 2010 CFR

...combustor metals, acid gases, organics, and nitrogen oxides. 60.33b Section 60.33b...metals, acid gases, organics, and nitrogen oxides. (a) The emission limits...plan shall include emission limits for nitrogen oxides at least as protective as...

2010-07-01

59

Solubilities and diffusion of trace gases in cold sulfuric acid films  

Microsoft Academic Search

The well-known technique of gas chromatography was used to determine solubilities and liquid-phase diffusion coefficients of trace gases in a thin sulfuric acid film deposited in a fused silica column. Solubilities of SO2, NO2, and N2O4 and the diffusion coefficient of SO2 were measured in the temperature range 203243K using sulfuric acid concentrations in the range of 3983wt%. The results

Stefan Langenberg; Volker Proksch; Ulrich Schurath

1998-01-01

60

Exposure assessment of oxidant gases and acidic aerosols  

SciTech Connect

Clearly the presence of high ozone and acidic species in North America is primarily dependent upon photochemical air pollution. Evidence shows, however, that high acid exposures may occur in specific types of areas of high sulfur fuel use during the winter. At the present time, our concerns about exposure to local populations and regional populations should be directed primarily toward the outdoor activity patterns of individuals in the summer, and how those activity patterns relate to the location, duration, and concentrations of ozone and acid aerosol in photochemical air pollution episodes. Lioy Dyba and Mage et al have examined the activity patterns of children in summer camps. Because they spend more time outside than the normal population, these children form an important group of exercising individuals subject to photochemical pollution exposures. The dose of ozone inhaled by the children in the two camps was within 50% and 25% of the dose inhaled by adults in controlled clinical situations that produced clinically significant decrements in pulmonary function and increased the symptoms after 6.6 hr exposure in a given day. The chamber studies have used only ozone, whereas in the environment this effect may be enhanced by the presence of a complex mixture. The work of Lioy et al in Mendham, New Jersey found that hydrogen ion seemed to play a role in the inability of the children to return immediately to their normal peak expiratory flow rate after exposure. The camp health study conducted in Dunsville, Ontario suggested that children participating in a summer camp where moderate levels of ozone (100 ppb) but high levels of acid (46 micrograms/m3) occurred during an episode had a similar response. Thus, for children or exercising adults who are outdoors for at least one hour or more during a given day, the presence and persistence of oxidants in the environment are of particular concern. 63 references.

Lioy, P.J.

1989-01-01

61

Automatic Carbon Dioxide-Methane Gas Sensor Based on the Solubility of Gases in Water  

PubMed Central

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 0100%. 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.

Cadena-Pereda, Raul O.; Rivera-Munoz, Eric M.; Herrera-Ruiz, Gilberto; Gomez-Melendez, Domingo J.; Anaya-Rivera, Ely K.

2012-01-01

62

Production of Low Temperature Coke in a Fluidized Bed Carbonizer. Heat Recovery from Crude Carbonization Gases - Investigations on a Technical Scale.  

National Technical Information Service (NTIS)

The present investigations have shown that the transport of crude and partially cleaned carbonization gases from a fluidized bed reactor can practically be handled, provided the condensed tar mist is completely removed by an electrostatic filter. The feas...

H. Kleinhueckelkotten

1981-01-01

63

Acid sorption regeneration process using carbon dioxide  

US Patent & Trademark Office Database

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.

2001-11-13

64

Chemical interactions between mineral dust particles and acid gases during Asian dust events  

NASA Astrophysics Data System (ADS)

Acid gas reactions during the passage from the source regions to the western North Pacific modify the chemical characteristics of Asian mineral dust particles as they pass through heavily industrial regions. We conducted aerosol samplings to investigate the interaction of mineral dust particles with acid gases in the western North Pacific region during the high-dust season. The concentration peaks of NO3- and mineral dust particles were in the coarse mode range (D > 1.25 ?m) in all aerosol samples, while non-sea-salt-(nss)-SO42- had an apparent peak in the coarse mode range only in an Asian dust event that experienced rain. Nitrate was the dominant acid substance associated with the mineral dust particles rather than nss-SO42-. In the urban air of Tokyo we also conducted an in situ experiment to react ambient acid gases with mineral dust particle loaded on a filter. The in situ experiment indicated that HNO3 had reacted with mineral dust particles much more efficiently than SO2 had. HNO3 (+NO2) and HCl accounted for large fractions (48% and 40%) of acid gases that reacted with mineral dust particles, while SO2 accounted for a small fraction (12%). The high adsorption of HNO3 on mineral dust particles would change their surface properties from hydrophobic to hygroscopic and form an efficient mechanism to remove nitrogen compounds to the ocean surface layer.

Ooki, Atsushi; Uematsu, Mitsuo

2005-02-01

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

Modeling of wormhole behavior in carbonate acidizing  

SciTech Connect

A mathematical model that describes the growth and competition of wormholes during an acidizing treatment in a carbonate formation is developed. The purpose of the treatment is to remove any near wellbore permeability damage created by drilling or completion fluids so that the production of reservoir fluids is stimulated. Hydrochloric acid is commonly used for this purpose. Since the acid solution tends to flow into the less resistant areas, large pores on the rock surface receive most acid fluid. Pores are enlarged due to the reaction between acid solution and carbonates. The growth of large pores in the formation is referred to as wormholing. Results from the model show that wormholes are formed due to the heterogeneity of carbonate rock and the reaction kinetics between acid and carbonates. Formation of a dominant wormhole is controlled by fluid diffusivity and fluid loss. Model results have good agreement with the results from published papers.

Hung, K.M.

1987-01-01

67

Amino acid composition of organic matter associated with carbonate and non-carbonate sediments  

Microsoft Academic Search

Amino acids comprise from 15 to 36% by weight of humic substances from carbonate and non-carbonate sediments. Humic and fulvic acids extracted from carbonate sediments are characterized by an amino acid composition consisting primarily of the acidic amino acids, aspartic and glutamic acid. Humic substances from non-carbonate sediments have a distinctly different amino acid composition consisting primarily of glycine and

Paul W. Carter; Richard M. Mitterer

1978-01-01

68

Evidence for high saturation of porous amorphous carbon films by noble gases  

NASA Astrophysics Data System (ADS)

Results of the electron diffraction study of Kr and Xe deposits on amorphous porous carbon substrates are reported. We have observed mixtures of crystallites typical of condensates formed at such substrates at low deposition temperatures. However, in the warming process at temperatures about three to five degrees below the sublimation point characteristic of flat substrates, the diffraction patterns demonstrate that large crystallites gradually disappear and a highly disordered matter forms. Such transformed samples are kept inside substrates several dozens degrees above the sublimation points which are typical of these substances on flat (e.g., metallic) substrates. We ascribe these features to specificity of composites formed from noble gases strongly bonded inside porous carbon matrices due to capillary filling at temperatures close to the sublimation points.

Krainyukova, N. V.

2009-04-01

69

Further evaluation of a two-week sampler for acidic gases and fine particles. Final report  

SciTech Connect

A Two-Week Sampler was designd to obtain exposure data for a long-term study involving children`s respiratory health by obtaining ambient concentrations of acidic gases (nitric, hydrochloric, formic, acetic) and particle-phase mass and ions (chloride, nitrate, sulfate, ammonium) < 2.5 um in aerodynamic diameter (PM2.5). Initial evaluations revealed that, while the sampler was precise for nitric acid and precise and accurate for inorganic ions, nitric acid measurements were biased high 15 to 30%. Laboratory tests conducted for this evaluation confirmed that while peroxyacetyl nitrate (PAN) and nitrous acid were capable of interfering with nitric acid measurements, field tests performed in ambient air indicated that the sampler measured nitric acid in good agreement with nylon filters.

Fitz, D.; Hering, S.

1996-05-01

70

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

71

Biogeochemical cycling of carbon, water, energy, trace gases, and aerosols in Amazonia: The LBA-EUSTACH experiments  

Microsoft Academic Search

The biogeochemical cycling of carbon, water, energy, aerosols, and trace gases in the Amazon Basin was investigated in the project European Studies on Trace Gases and Atmospheric Chemistry as a Contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA-EUSTACH). We present an overview of the design of the project, the measurement sites and methods, and the meteorological conditions during the

M. O. Andreae; P. Artaxo; C. Brando; F. E. Carswell; P. Ciccioli; A. L. da Costa; A. D. Culf; J. L. Esteves; J. H. C. Gash; J. Grace; P. Kabat; J. Lelieveld; Y. Malhi; A. O. Manzi; F. X. Meixner; A. D. Nobre; C. A. Nobre; M. d. L. P. Ruivo; M. A. F. da Silva-Dias; P. Stefani; R. Valentini; J. von Jouanne; M. J. Waterloo

2002-01-01

72

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

73

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

74

Effect of gases on the temperature dependence of the electric conductivity of CVD multiwalled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The influence of various gaseous media on the temperature dependence of the electric conductivity ? of multiwalled carbon nanotubes (MWNTs) synthesized using the method of catalytical chemical vapor deposition (CVD) has been studied. The ?( T) curves were measured in a temperature range from 4.2 to 300 K in helium and its mixtures with air, methane, oxygen, and hydrogen. The introduction of various gaseous components into a helium atmosphere leads to a significant decrease in the conductivity of MWNTs in the interval between the temperatures of condensation and melting of the corresponding gas. Upon a heating-cooling cycle, the conductivity restores on the initial level. It is concluded that a decrease in ? is caused by the adsorption of gases on the surface of nanotubes.

Buryakov, T. I.; Romanenko, A. I.; Anikeeva, O. B.; Kuznetsov, V. L.; Usol'Tseva, A. N.; Tkachev, E. N.

2007-07-01

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

Molecular and carbon isotopic variability of hydrocarbon gases from mud volcanoes in the Gulf of Cadiz, NE Atlantic  

Microsoft Academic Search

Investigations of molecular and carbon isotopic variability of hydrocarbon gases from methane through butanes (pentanes) have been performed on six mud volcanoes from two fluid venting provinces located in the Gulf of Cadiz, NE Atlantic. The main aims were to define the basic gas types, to describe their geochemical characteristics in relationship to their sources, and to determine the secondary

Alina Stadnitskaia; Michail K. Ivanov; Valentina Blinova; Rob Kreulen; Tjeerd C. E. van Weering

2006-01-01

77

Adsorption of acidic gases by palygorskite modified by copper cations and ammonia  

SciTech Connect

Ion-exchange replacement of the exchange cations of native palygorskite by copper(II) cations leads to a significant increase in the uptake of the electron-acceptor molecules HCl and SiF/sub 4/ by the cation-substituted samples, but reduces the adsorption of SO/sub 2/ and NO/sub 2/. Presorption of NH/sub 3/ by the copper-substituted palygorskite gives a substantial increase in the adsorption of all of the indicated sorbates. A judgment is made regarding the mechanism of adsorptive interaction of acidic gases with the surface of palygorskite modified with copper cations and ammonia.

Kats, B.M.; Tarasevich, Yu.I.; Malinovskii, E.K.

1986-11-01

78

Adsorption and separation of binary mixtures of noble gases on single-walled carbon nanotube bundles  

NASA Astrophysics Data System (ADS)

Adsorption and separation of binary mixtures of noble gases including Argon (Ar), Krypton (Kr), and Xenon (Xe) on (10,10) single-walled carbon nanotube (SWCNT) bundles is simulated by extensive equilibrium molecular dynamics (MD). Adsorption energies, diffusion coefficients, activation energies, and radial distribution functions (RDFs) were calculated to address the thermodynamics, transport and structural properties of adsorption process. The simulation results of exposing Ar-Kr, Ar-Xe, and Kr-Xe mixtures on (10,10) SWCNT bundles at temperatures of 75, 150, and 300 K, show that amount of adsorption is strongly influenced by the applied temperature. On the other hand, RDF plots show obviously that separation of binary gaseous mixture is occurred, where the heavier noble gas is adsorbed more than the lighter one in a selective manner by bundle. It is seen that the increase in the applied temperature results in more separation. These findings provide us a possible application of carbon nanotubes (CNTs) as efficient nanomaterials for separation and storage of gas mixtures.

Foroutan, Masumeh; Taghavi Nasrabadi, Amir

2011-02-01

79

Combustion vs. Pyrolysis of Presolar Diamonds: Association of P3 and HL Noble Gases with Carbon  

NASA Astrophysics Data System (ADS)

Since it became clear that presolar diamonds are not identical and perhaps consist of several carriers of isotopically anomalous (like HL-Xe and light nitrogen) and isotopically normal (carbon and P3 noble gases) components, it is important to know how these components are related to the diamond carriers. Because of diamond grains are too small to be analyzed individually and the attempts to separate the diamonds [1] have had little, if any, success, the only method currently available to investigate the relationship between the carriers and corresponding components is the temperature dependence of their release pattern. The interpretation of the latter however is often not straight forward because the mechanism by which the gases are released is complicated and simultaneously involves several processes such as diffusion, chemical reactions between coexisting phases and/or their heating environment and phase transformations [2, 3]. To unravel this interdependent matrix we use several extraction methods applied to the same sample. In the present study we used a combination of stepped pyrolysis and combustion for investigation of the release pattern of Ar components for presolar diamonds concentrated from CI (Orgueil), and CV (Allende, Efremovka) meteorites. From the previous studies [2] it is known that Ar in the most primitive CI's and CM's meteorites consists mostly of P3 component while for CV3's like Allende and Efremovka it is represented mainly by HL component. This difference in the noble gas components composition probably reflects the thermal history of the corresponding parent bodies and the extreme sensitivity of the P3 component concentrations, in presolar diamonds, to the thermal metamorphism. Laboratory pyrolysis experiments show that most of the P3 argon is released at rather low temperature though some of the gas is still being liberated at temperatures as high as those usually associated with HL component [2]. The low release temperatures have led to the idea that P3 noble gases are located near the surface of the diamond grains which is destroyed by pyrolytically induced chemical reactions with surface bonded H atoms [2]. However the same authors did not comment on the high temperature part of the P3 release. Our previous investigations [4] however have clearly showed that the release of P3 component during pyrolysis is accompanied by of 8-15% of C present in the form of CO+C02. This observation is in agreement with the amount of oxygen which can be adsorbed on the surface of diamond grains. The evolution of C02+CO is in any case independent of whether or not external oxygen is used for the extraction. Analysis of a high resolution release pattern of 36Ar from Orgueil shows (Fig.) that it is bimodal and similar for pyrolysis and combustion. There is a fraction of P3 Ar (~40%) which is released at low temperature apparently by diffusion before the carbon begins to combust. The rest of the P3 Ar in the case of combustion, and another 40 - 50% in the case of pyrolysis, is released in close association with release of carbon. We conclude that the P3 component has a complicated nature and some difference in the isotopic composition of its constituents may be suggested. It is important to note that release of Ar P3 occurs over the whole temperature range of diamond combustion (450-600 degrees C) independent of how much oxygen is available (Fig.). This is evidence against a location of P3 gases on the surface of the diamond grains but suggests a separate camer for the component. The release of about 10% of P3 gases at very high temperature during pyrolysis [2] can be simply explained if the amount of the oxygen associated with the sample is not enough to oxidize all the P3-containing grains. The release of P3 gases together with HL component contradicts their surface location. We believe these is now a strong case for P3 gas (Ar at least) in Orgueil being associated with a distinct type of grain which constitutes ~10% by weight of the carbon. In contrast to the above a high resolution stepped combustion extract

Verchovsky, A. B.; Fisenko, A. V.; Pillinger, C. T.

1995-09-01

80

SEPARATION OF CO2 FROM FLUE GASES BY CARBON-MULTIWALL CARBON NANOTUBE MEMBRANES  

SciTech Connect

Multiwalled carbon nanotubes (MWNT) were found to be an effective separation media for removing CO{sub 2} from N{sub 2}. The separation mechanism favors the selective condensation of CO{sub 2} from the flowing gas stream. Significant uptakes of CO{sub 2} were measured at 30 C, 150 C and 300 C over the pressure range 0.5 to 5 bar. No measurable uptake of nitrogen was found for this range of conditions. The mass uptake of CO{sub 2} by MWNT was found to increase with increasing temperature. A packed bed of MWNT completely removed CO{sub 2} from a flowing stream of CO{sub 2}/N{sub 2}, and exhibited rapid uptake kinetics for CO{sub 2}.

Rodney Andrews

2001-11-01

81

SEPARATION OF CO2 FROM FLUE GASES BY CARBON-MULTIWALL CARBON NANOTUBE MEMBRANES  

SciTech Connect

Multiwalled carbon nanotubes (MWNT) were found to be an effective separation media for removing CO{sub 2} from N{sub 2}. The separation mechanism favors the selective condensation of CO{sub 2} from the flowing gas stream. Significant uptakes of CO{sub 2} were measured at 30 C and 150 C over the pressure range 0.5 to 5 bar. No measurable uptake of nitrogen was found for this range of conditions. The mass uptake of CO{sub 2} by MWNT was found to increase with increasing temperature. A packed bed of MWNT completely removed CO{sub 2} from a flowing stream of CO{sub 2}/N{sub 2}, and exhibited rapid uptake kinetics for CO{sub 2}.

Rodney Andrews

2001-03-01

82

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 0.9C compares well with the observation-based estimate of 0.76 0.19C. The RCP 2.6, 4.5 and 8.5 scenarios respectively yield warmings of 1.4, 2.3, and 4.9C and cumulative diagnosed fossil fuel emissions of 182, 643 and 1617 Pg C over the 2006-2100 period. The simulated warming of 2.3C over the 1850-2100 period in the RCP 2.6 scenario, with the lowest concentration of GHGs, is slightly larger than the 2C 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 2C 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

83

Effect of foams used during carbonate acidizing  

SciTech Connect

Although acidization has been used successfully for many years to increase the productivity of petroleum wells in carbonate formations, demands on the performance and application of the acidizing process are increasing. This paper investigates a method of in-situ foam generation that allows deeper wormhole penetration yet uses less acid than conventional methods. The dissolution patterns were imaged with neutron radiography, which provided an in-depth understanding of the effects of foam and other critical parameters. Results show that foam is effective in promoting efficient stimulation, even at low acid injection rates.

Bernadiner, M.G. (Mechanical Engineering Dept., New York Polytechnic Univ., Brooklyn, NY (United States)); Thompson, K.E. (Michigan Univ., Ann Arbor, MI (United States)); Fogler, H.S. (Michigan Univ., Ann Arbor, MI (United States). Dept. of Chemical Engineering)

1992-11-01

84

Carbon dioxide recovery from flue gases of a conventional coal-fired power plant using polymer membranes  

Microsoft Academic Search

\\u000a To reduce the emission of carbon dioxide from a conventional coal-fired power plant, carbon dioxide can be separated from\\u000a the flue gases by using polymer membranes. In this chapter a theoretical investigation into the technological and economic\\u000a outlook of this option is described.\\u000a \\u000a \\u000a At present the best types of membranes available for separating carbon dioxide from nitrogen are non-porous polymer

Chris Hendriks

85

Soluble species in the Arctic summer troposphere: Acidic gases, aerosols, and precipitation  

NASA Astrophysics Data System (ADS)

We report here the distribution of selected acidic gases and aerosol species in the North American Arctic and sub-Arctic summer troposphere. The summertime troposphere is an acidic environment, with HCOOH and CH3COOH the principal acidic gases and acidic sulfate aerosols dominating the particulate phase. Our data show that the acidic gas and aerosol composition is uniform on a large spatial scale. There appears to be a surface source of NH4+ over the Arctic Ocean pack ice which may reflect release of NH3 from decay of dead marine organisms on the ice surface near ice leads, release from rotting sea ice, or an upward flux from surface ocean waters in open ice leads. This NH3 appears to partially neutralize aerosol acidity in the boundary layer. Over sub-Arctic tundra in southwestern Alaska inputs of marine biogenic sulfur from the nearby Bering Sea appear to be an important source of boundary layer aerosol SO42-. While there were only minor effects on aerosol chemistry over the tundra from sea salt, the rainwater chemistry showed influence from marine aerosols which were apparently incorporated into air masses during frontal passages moving inland from the Bering Sea. The rainwater acidity over the tundra (pH 4.69) is typical of remote regions. The principal acidity components are H2SO4 and carboxylic acids, especially HCOOH. The carboxylic acids appear to have a strong continental biogenic source, but hydrocarbons of marine origin and emissions from forest fires may also be important. The wet deposition fluxes of NO3--N and SO42--S over sub-Arctic tundra during July-August 1988 were 2.1 and 2.4 mmol m-2 yr-1. Wet deposition of NO3- was nearly 3 times higher than the average NOy deposition flux, which is believed to represent primarily dry deposition of HNO3 (Bakwin et al., this issue). Our measurements indicate that the mid-troposphere in the Arctic is generally contaminated with low levels of anthropogenic pollutants even in summer when direct atmospheric coupling with mid-latitude source regions was previously believed to be minimal. Stratospheric inputs may also be important as a source of Arctic tropospheric SO42-. On several occasions we sampled directly within plumes or highly contaminated air masses representing various anthropogenic sources. The composition of these pollution sources suggested that they were important in determining the large-scale distribution of acidic gases and aerosol species in the Arctic summer troposphere. Outside the plumes the anthropogenic influences are chemically diffuse and variable, making it very difficult to quantitatively ascertain the magnitude of the effects. Present-day "background" air during summertime in the North American Arctic and sub-Arctic mid-troposphere appears to have the following average composition (parts per trillion by volume): HCOOH (70), CH3COOH (70), HNO3 (40), NO3- (10), SO42- (25), and NH4+ (55). These concentrations which were observed on only a few isolated days can be compared to the grand average (Arctic and sub-Arctic) mid-tropospheric levels during July-August 1988: HCOOH (166 81), CH3COOH (215 90), HNO3 (48 29), NO3- (22 17), SO42- (61 30), and NH4+ (68 30). A "first-look" comparison of the large-scale mid-tropospheric composition in a remote area of the northern hemisphere with that over a remote region of the southern hemisphere, the Amazon Basin, suggests no identifiable difference in the levels of NH4+ but possibly twofold and fivefold enhancement of NO3- and SO42- in "background" air for North America.

Talbot, R. W.; Vijgen, A. S.; Harriss, R. C.

1992-10-01

86

Acid gases partial pressures above a 50 wt% aqueous methyldiethanolamine solution: Experimental work and modeling  

Microsoft Academic Search

Aqueous amine solutions are widely used in the industry for acid gas removal. In order to treat natural gas or refinery process streams, an accurate knowledge of solubility data of carbon dioxide, hydrogen sulfide and other sulfur species in aqueous amine solutions is required. In this paper, new equilibrium measurements on 50wt% aqueous methyldiethanolamine solution with CO2 and H2S have

Moussa Dicko; Christophe Coquelet; Carmen Jarne; Scott Northrop; Dominique Richon

2010-01-01

87

Measurement, analysis, and modeling of gas-to-particle conversion between ammonia, acid gases, and fine particles  

NASA Astrophysics Data System (ADS)

Since 1990, the population of hogs in eastern North Carolina has increased sharply resulting in increased emissions of ammonia. An Annular Denuder System (ADS) was used, which consisted of a cyclone separator, two diffusion denuders coated with sodium carbonate and citric acid, respectively, and a filter pack consisting of Teflon and nylon filters in series. The ADS measured ammonia, acid gases, and fine particles in ambient atmosphere at a commercial hog farm in Eastern North Carolina from April 1998 to March 1999. The sodium carbonate coated denuders yielded average acid gas concentrations of 0.23 mug/m 3 HCl (+/-0.20 mug/m3); 1.10 mug/m 3 HONO (+/-1.17 mug/m3); 1.14 mug/m 3 HNO3 (+/-0.81 mug/m3), and 1.61 mug/m 3 SO2 (+/-1.58 mug/m3). The citric acid coated denuders yielded an average concentration of 17.89 mug/m 3 NH3 (+/-15.03 mug/m3). The filters yielded average fine aerosol (i.e., fine particular matter, Dp ? 2.5 mum) concentrations of 1.64 mug/m3 NH4+ (+/-1.26 mug/m3); 0.26 mug/m3 Cl - (+/-0.69 mug/m3); 1.92 mug/m 3 NO3- (+/-1.09 mug/m 3), and 3.18 mug/m3 SO42- (+/-3.12 mug/m3). Using the data collected from the study sites, we evaluated the seasonal variations and the effects of relative humidity on fine particle species. Based on the measurements of ammonia, acid gases, and fine particles, the mean pseudo-first-order rate constant, kS, between NH3 and H2SO4 aerosol is estimated to be 3.70 (+/-2.99) x 10-3 sec-1. The rate constant was found to increase as temperature increases, and decrease with increasing relative humidity. The equilibrium time constant was determined based on the estimated kinetic rate constants and the observed inorganic components of atmospheric aerosols. The average value of equilibrium time constant was determined to be 17.01 (+/-12.19) minutes for ambient equilibrium time between ammonia, nitric acid gas and ammonium nitrate aerosol; and 10.83 (+/-8.97) minutes for ammonia, hydrochloric acid, and ammonium chloride. The aerosol chemical compositions predicted by the use of a thermodynamic equilibrium model (EQUISOLV II) were in good agreement for ammonium and under-estimated nitrate aerosol when compared with the observed chemical composition at the experimental site.

Baek, Bok-Haeng

88

Sources of hydrocarbon gases in mud volcanoes from the Sorokin Trough, NE Black Sea, based on molecular and carbon isotopic compositions  

Microsoft Academic Search

Molecular and stable carbon isotope properties of hydrocarbon gases (methane through pentanes and sometimes hexanes) from seven sediment cores collected from five mud volcanoes (MVs) in the Sorokin Trough (NE Black Sea) suggest that these gases are initially derived from the comparable hydrocarbon pools and are likely initial products of non-microbial oil cracking processes. Our results state that dry characteristics

A. Stadnitskaia; M. K. Ivanov; E. N. Poludetkina; R. Kreulen; T. C. E. van Weering

2008-01-01

89

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...

90

Mixed venous blood gases are superior to arterial blood gases in assessing acid-base status and oxygenation during acute cardiac tamponade in dogs.  

PubMed Central

Recent reports using anesthetized ventilator-dependent animal models, have suggested that in certain shock states, a disparity exists between arterial and mixed venous blood gases with regard to acid-base status and oxygenation. In a chronically instrumented unanesthetized canine model of acute cardiac tamponade breathing room air, we studied the effect of a graded decline in cardiac output on arterial and mixed venous pH, PCO2, and PO2. Cardiac tamponade resulted in a profound arterial respiratory alkalosis, whereas mixed venous pH, PCO2, and calculated serum bicarbonate levels remained relatively unchanged. As intrapericardial pressure increased and cardiac output declined, the difference between arterial and mixed venous PCO2 progressively increased. Further, whereas arterial oxygenation improved as cardiac output declined, mixed venous oxygenation steadily worsened. This disparity began early in cardiac tamponade (reductions in cardiac output of 20-40%) long before arterial blood pressure began to fall and progressively worsened as hemodynamic deterioration and lactic acidosis developed. Our findings are consistent with the hypothesis that a reduction in blood flow, resulting in decreased CO2 delivery to the lungs, is the primary mechanism responsible for the difference in pH and PCO2 observed between arterial and mixed venous blood. In this conscious, spontaneously breathing animal model, mixed venous blood gases thus are superior to arterial blood gases in assessing acid-base status and oxygenation, even early in acute cardiac tamponade when the decline in cardiac output is in the range of 20 to 40% and arterial blood pressure has not changed significantly.

Mathias, D W; Clifford, P S; Klopfenstein, H S

1988-01-01

91

On the Solubility of Glycerides and Fatty Acids in Compressed Gases in the Presence of an Entrainer  

Microsoft Academic Search

The solubility of fatty acids and their glycerides in dense supercritical gases increases with increasing pressure at constant temperature. The temperature influences the solution equilibria in a more complicated way than the pressure. Addition of an entrainer increases the solubility in the gas phase. Furthermore, the temperature dependence of the solvent power is increased so much that the regeneration of

G. Brunner; S. Peter

1982-01-01

92

Prediction of effective acid penetration and acid volume for matrix acidizing treatments in naturally fractured carbonates  

SciTech Connect

This paper discusses a new method and a corresponding computer model developed to investigate matrix acidizing in naturally fractured carbonates. With this method, the effective acid penetration distance and acid volume needed for acid treatments in naturally fractured carbonates can be predicted. The new model simulates acid flowing in the natural fracture network and the acid/rock reaction. During the simulation, the model considers the influence of formation temperature, reaction heat, and common ion effect on acid penetration. A set of graphs showing the relationship between acid penetration and the acid volume needed in different formations was developed from numerical simulation results. From these plots, the acid volume that should be used to remove the formation damage can be determined easily when the formation temperature and the damage radius are known or can be estimated.

Xiong, H. (S.A. Holditch and Associates, Inc., College Station, TX (United States))

1994-08-01

93

Calcium, carbonic anhydrase and gastric acid secretion.  

PubMed

Previous data concerning the action of calcium (Ca) on gastric acid secretion (GAS) indicated that calcium ions increase GAS elicited by gastrin released through a vagal mechanism, and also by a direct effect on parietal cells. Our research showed that the stimulating effect of calcium on gastric acid secretion can be antagonized by verapamil administration, which reduces gastric acid secretion . In the present study we followed the effect induced by administration of calcium and Ca-chelating agents (disodium EDTA) on gastric acid secretion and on carbonic anhydrase (CA) activity. We selected two groups of healthy volunteers: Group I (n=21) received a single i.v. dose of CaCl2 (15 mg/kg b.w.), whereas Group II (n=22) received a single i.v. dose of disodium EDTA (5 mg/kg b.w.). We determined blood calcium before and after treatment, gastric acid secretion at 2 hours. erythrocyte CA II activity, and CA IV activity in membrane parietal cells, which were isolated from gastric mucosa obtained by endoscopic biopsy. Assessment of carbonic anhydrase activity was achieved by the stopped-flow method. In Group I calcium administration increased blood calcium, HCl output, CA II and CA IV activity as compared to initial values. In Group II, disodium EDTA reduced blood calcium, HCl output, CA II and CA IV activity as compared to initial values. The results demonstrated that increased blood calcium and GAS values after calcium administration correlated with the increase of erythrocyte CA II and parietal cell CA IV activity, while disodium EDTA induced a reversed process. Our results also show that cytosolic CA II and membrane CA IV values are sensitive to calcium changes and they directly depend on these levels. Our data suggest that intra- and extracellular pH changes induced by carbonic anhydrase might account for the modulation of the physiological and pathological secretory processes in the organism. PMID:11551141

Puscas, I; Coltau, M; Baican, M; Domuta, G; Hecht, A

2001-01-01

94

A Widely Tunable Infrared Laser Spectrometer for Measurements of Isotopic Ratios of Carbon Cycle Gases  

SciTech Connect

The atmospheric abundances of carbon dioxide and methane have increased dramatically during the industrial era. Measurements of the isotopic composition of these gases can provide a powerful tool for quantifying their sources and sinks. This report describes the development of a portable instrument for isotopic analysis CO{sub 2} and CH{sub 4} using tunable infrared laser absorption spectroscopy. This instrument combines novel optical design and signal processing methods with a widely tunable mid-infrared laser source based on difference frequency generation (DFG) which will can access spectral regions for all the isotopes of CO{sub 2} and CH{sub 4} with a single instrument. The instrument design compensates for the large difference in concentration between major and minor isotopes by measuring them with path lengths which differ by a factor of 100 within the same multipass cell. During Phase I we demonstrated the basic optical design and signal processing by determining {sup 13}CO{sub 2} isotopic ratios with precisions as small as 0.2{per_thousand} using a conventional lead salt diode laser. During Phase II, the DFG laser source was coupled with the optical instrument and was demonstrated to detect {sup 13}CH{sub 4}/{sup 12}CH{sub 4} ratios with a precision of 0.5{per_thousand} and an averaging time of 20 s using concentrated methane in air with a mixing ratio of 2700 ppm. Methods for concentrating ambient air for isotopic analysis using this technique have been evaluated. Extensions of this instrument to other species such as {sup 13}CO{sub 2}, C{sup 18}OO, and CH{sub 3}D are possible by substituting lasers at other wavelengths in the DFG source module. The immediate commercial application of this instrument will be to compete with existing mass spectrometric isotope instruments which are expensive, large and relatively slow. The novel infrared source developed in this project can be applied to the measurement of many other gas species and will have wide application in atmospheric monitoring, industrial process control, and medical research and diagnostic development.

Joanne H. Shorter; J. Barry McManus; David D. Nelson; Charles E. Kolb; Mark S. Zahniser; Ray Bambha; Uwe Lehmann; Tomas Kulp; Stanley C. Tyler

2005-01-31

95

One-step synthesis of carbon functionalized with sulfonic acid groups using hydrothermal carbonization  

Microsoft Academic Search

Carbon functionalized with sulfonic acid groups has been synthesized using the one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid aqueous solution at 180C for 4h. The carbon exhibited high acidity and comparable activities to sulfuric acid for the traditional acid-catalyzed reactions, which indicated that it has great potential for environment-friendly processes. The copolymerization method provides an efficient procedure for the

Xuezheng Liang; Minfeng Zeng; Chenze Qi

2010-01-01

96

One-step synthesis of novel sulfuric acid groups' functionalized carbon via hydrothermal carbonization  

Microsoft Academic Search

The novel sulfuric acid groups' functionalized carbon has been synthesized via one-step hydrothermal carbonization of polyvinyl alcohol and hydroxyethylsulfuric acid. The novel carbon exhibited high acidity and comparable activities to sulfonic acid for the traditional acid-catalyzed reactions, which indicated that it has great potential for the environmental-friendly processes. The copolymerization method provides an efficient procedure for the synthesis of various

Xuezheng Liang; Huiquan Xiao; Yongmiao Shen; Chenze Qi

2010-01-01

97

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

PubMed

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 275C 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 ?g I-TEQ kg(-1) toxic PCDD/F was formed in the refuse derived fuel activated carbon compared to 34 ?g I-TEQ kg(-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. PMID:21334872

Hajizadeh, Yaghoub; Onwudili, Jude A; Williams, Paul T

2011-02-21

98

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

99

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

100

Selection of catalyst and conditions for the removal of carbon monoxide and organic vapors from exhaust gases of the regenerator of oil cracking plants  

Microsoft Academic Search

Considerable quantities of carbon monoxide and organic vapors are known to occur in the exhaust gases during regeneration of an oil cracking catalyst. A catalytic method using expensive catalysts based on precious metals is regarded as the most widespread method of removing carbon monoxide and organic vapors from gaseous exhausts. In order to carry out purification by this method, it

I. O. Krylov; O. I. Bleskin; A. V. Krylova

1995-01-01

101

Acid-treated soy hull carbon structure and adsorption performance  

Microsoft Academic Search

The objective of this study was to evaluate the effect of 14 N phosphoric acid and 12 N hydrochloric acid treatments on soy\\u000a hull carbon structure and adsorption performance. Scanning electron micrographs showed that acid treatments disrupted the\\u000a carbon structure whereas X-ray diffraction data indicated that hydrochloric acid had a greater effect than phosphoric acid\\u000a in creating a more amorphous

Yan Hong; Andrew Proctor; John Shultz

2000-01-01

102

Synthesis of a Novel Carbon Based Strong Acid Catalyst Through Hydrothermal Carbonization  

Microsoft Academic Search

A novel carbon based strong acid catalyst has been synthesized through the sulfonation of the carbon materials from glucose.\\u000a The novel acid catalyst was obtained through the hydrothermal carbonization instead of the traditional heat treatment, which\\u000a made the carbonization process under much milder condition with higher yield. The novel heterogeneous catalyst owned the advantages\\u000a of high acidity as much as

Xuezheng Liang; Jianguo Yang

2009-01-01

103

Chemistry of the molten carbonate process for SO removal from stack gases  

Microsoft Academic Search

The Molten Carbonate Process consists of three steps: the scrubbing of SO by a ternary eutectic alkali metal carbonate melt; the reduction of the sulfite and sulfate reaction products with petroleum coke; and the reaction of the resulting sulfide with steam and CO to regenerate the carbonate and to form HS, which in turn can be converted to elemental sulfur.

S. J. Yosim; L. F. Grantham; D. E. McKenzie; G. C. Stegmann

1976-01-01

104

Influence of experimental Eimeria zuernii infection in calves on electrolyte concentrations, acidbase balance and blood gases  

Microsoft Academic Search

Coccidiosis, often caused by Eimeria zuernii, is an important disease in calf rearing and is clinically mainly associated with diarrhoea (PR Fitzgerald in Adv Vet Sci\\u000a Comp Med, 24:121143, 1980). Calves were experimentally infected with E. zuernii oocysts to investigate the effects of artificial E. zuernii coccidiosis on electrolyte concentrations, acidbase balance and blood gases. Therefore, animals were assigned to

B. Bangoura; A. Daugschies

2007-01-01

105

Electrochemical determination of tartaric acid at nano gold/nano carbon modified glassy carbon electrode  

NASA Astrophysics Data System (ADS)

Nano gold/nano carbon coating the surface of glassy carbon electrode is prepared. Electrochemical behavior of tartaric acid at nano gold/graphene modified glassy carbon electrode is investigated. A simple, sensitive, and inexpensive method for determination of tartaric acid in drinks is proposed.

Song, Yang; Song, Yuanzhi; Xu, Jiang

2012-09-01

106

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

107

Investigation of amine amino acid salts for carbon dioxide absorption  

Microsoft Academic Search

The carbon dioxide capture potential of amine amino acid salts (AAAS), formed by mixing equinormal amounts of amino acids; e.g. glycine, ?-alanine and sarcosine, with an organic base; 3-(methylamino)propylamine (MAPA), was assessed by comparison with monoethanolamine (MEA), and with amino acid salt (AAS) from amino acid neutralized with an inorganic base; potassium hydroxide (KOH). Carbon dioxide absorption and desorption experiments

Ugochukwu E. Aronu; Hallvard F. Svendsen; Karl Anders Hoff

2010-01-01

108

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 5 performed at less than 100C, including ambient room temperature, with a radio frequency plasma assisted chemical vapor deposition process. With less than 6.5 at% fluorine incorporated into the amorphous carbon film, the characteristics of the carbon film, including index of 10 refraction, mass density, optical clarity, and chemical resistance are within 15% of those characteristics for pure amorphous carbon films, but the deposition rates are high.

Stafford, B.L.; Tracy, C.E.; Benson, D.K.; Nelson, A.J.

1991-03-15

109

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

110

Control of mercury emissions in flue gases by activated carbon adsorption  

Microsoft Academic Search

The adsorptive capacities of virgin and sulfur impregnated activated carbons (GAC) for gas-phase mercury were evaluated as a function of temperature and influent mercury concentration. The virgin activated carbon showed little adsorptive capacity, especially at temperatures above 90 °C. The pronounced effect of temperature on the adsorptive capacity evidences a physical adsorption mechanism between the mercury and virgin GAC. Sulfur

Vidic

1996-01-01

111

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

112

Activated carbons prepared from phosphoric acid activation of grain sorghum  

Microsoft Academic Search

The production of activated carbons from grain sorghum with phosphoric acid activation has been studied by means of two processes, i.e., one-stage and two-stage. The former comprises simultaneous carbonization and activation after impregnation; the latter, the carbonization of the precursor at 300 C for 15 min, followed by the activation of the resultant char after impregnation with phosphoric acid. The

Yulu Diao; W. P Walawender; L. T Fan

2002-01-01

113

Sorption of noble gases by solids, with reference to meteorites. I - Magnetite and carbon  

NASA Astrophysics Data System (ADS)

The trapping of meteoritic noble gases by solids is simulated through the synthesis of 18 Fe3O4 samples at 350-720 K in a noble gas atmosphere, by means of the reactions: (1) 3Fe + 4H2O yields Fe3O4 + 4H2, using Ne, Ar, Kr and Xe; and (2) 3Fe + 4CO yields Fe3O4 + 4C + carbides, using Xe. Etching experiments suggest an analogy with 'Phase Q' in meteorites. Adsorbed atmospheric gases are present in all samples, and dominate whenever the noble gas partial pressure in the atmosphere is greater than that in the synthesis. While many of the results of Lancet and Anders (1973) appear to have been dominated by such an atmospheric component, others are suspect. When the doubtful samples of Lancet and Anders are corrected or eliminated, the fractionation pattern no longer peaks at Ar, but rather, as in the present sample, rises monotonically from Ne to Xe. No evidence is found for the earlier study's claim of a strong temperature dependence.

Yang, J.; Lewis, R. S.; Anders, E.

1982-06-01

114

High rate chemical vapor deposition of carbon films using fluorinated gases  

Microsoft Academic Search

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 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,

B. L. Stafford; C. E. Tracy; D. K. Benson; A. J. Nelson

1993-01-01

115

High rate chemical vapor deposition of carbon films using fluorinated gases  

Microsoft Academic Search

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 5 performed at less than 100C, including ambient room temperature, with a radio frequency plasma assisted chemical vapor deposition process. With less than 6.5 at% fluorine incorporated into the amorphous carbon film,

B. L. Stafford; C. E. Tracy; D. K. Benson; A. J. Nelson

1991-01-01

116

High rate chemical vapor deposition of carbon films using fluorinated gases  

Microsoft Academic Search

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,

Byron L. Stafford; C. Edwin Tracy; David K. Benson; Arthur J. Nelson

1993-01-01

117

PVT measurements of carbon dioxide + nitrogen and an equation of state development for natural and hydrocarbon gases  

SciTech Connect

Densities of five mixtures of carbon dioxide + nitrogen (0.10560, 0.25147, 0.50365, 0.71105, 0.90921) and pure nitrogen were measured at 300 and 320 K at pressures to 10 MPa using the Burnett technique. Second and third virial coefficients and densities were derived for each mixture from the measurements. Cross second and third virial coefficients were determined at each temperature. Several methods for calculating cross third virial coefficients are compared with the experimental values. The methods considered are: ideal solution, geometric mean, the Orbey and Vera correlation, Lennard-Jones, the MHEMHS model, and an algebraic determination using two mixture third virial coefficients. A continuously weighed pycnometer has been used to measure densities of the mixtures in the dense gas and liquid regions at temperatures from 225 to 450 K at pressures to 70 MPa. A procedure has been developed which uses this apparatus to detect phase transitions. Saturation densities and pressures are reported for those isotherms where phase transitions occur. A flexible foil gravity mixer is described which has been developed to assist in the preparation of gas mixtures of accurately known composition without contaminating the mixtures. A new automated temperature measurement and control scheme is described which has been implemented on both the Burnett apparatus and the pycnometer. A new equation of state has been developed for hydrocarbon gases based upon the truncated virial equation. The new equation can be applied to natural gases containing hydrocarbons, nitrogen and carbon dioxide by treating the hydrocarbon fraction of the mixture as a single component and using simple combining rules to calculate the cross virial coefficients without introducing additional parameters.

Brugge, H.B.

1989-01-01

118

Fluorescent Carbon Dots Capped with PEG 200 and Mercaptosuccinic Acid  

Microsoft Academic Search

The synthesis and functionalization of carbon nanoparticles with PEG200 and mercaptosuccinic acid, rendering fluorescent carbon dots, is described. Fluorescent carbon dots (maximum excitation and\\u000a emission at 320 and 430nm, respectively) with average dimension 267nm were obtained. The lifetime decay of the functionalized\\u000a carbon dots is complex and a three component decay time model originated a good fit with the following

Helena Gonalves; Joaquim C. G. Esteves da Silva

2010-01-01

119

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 142 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

120

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 142 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

121

Control of mercury emissions in flue gases by activated carbon adsorption  

SciTech Connect

The adsorptive capacities of virgin and sulfur impregnated activated carbons (GAC) for gas-phase mercury were evaluated as a function of temperature and influent mercury concentration. The virgin activated carbon showed little adsorptive capacity, especially at temperatures above 90 {degrees}C. The pronounced effect of temperature on the adsorptive capacity evidences a physical adsorption mechanism between the mercury and virgin GAC. Sulfur impregnated activated carbons exhibited enhanced mercury removal efficiency over the non-impregnated varieties due to formation of mercuric sulfide on the carbon surface. This chemisorption process is enhanced with increased temperature between 25 and 90 {degrees}C. However, at 140 {degrees}C a decrease in adsorptive capacity occurs, indicating reduced formation of mercuric sulfide. The method used for impregnating GAC with sulfur had a pronounced effect on mercury removal capacity. The chemical bonding of sulfur and carbon surface at 600 {degrees}C provides a more uniform distribution of sulfur throughout the GAC pore structure than achieved by conventional condensation techniques, yielding improved performance.

Vidic, R.D. [Univ. of Pittsburgh, PA (United States)

1996-12-31

122

Apparatus for purifying arsine, phosphine, ammonia, and inert gases to remove Lewis acid and oxidant impurities therefrom  

DOEpatents

An apparatus for purifying a gaseous mixture comprising arsine, phosphine, ammonia, and/or inert gases, to remove Lewis acid and/or oxidant impurities therefrom, comprising a vessel containing a bed of a scavenger, the scavenger including a support having associated therewith an anion which is effective to remove such impurities, such anion being selected from one or more members of the group consisting of: (i) carbanions whose corresponding protonated compounds have a pK.sub.a value of from about 22 to about 36; and (ii) anions formed by reaction of such carbanions with the primary component of the mixture.

Tom, Glenn M. (New Milford, CT); Brown, Duncan W. (Wilton, CT)

1991-01-08

123

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

124

Carbon flux and fatty acid synthesis in plants  

Microsoft Academic Search

The de novo synthesis of fatty acids in plants occurs in the plastids through the activity of fatty acid synthetase. The synthesis of the malonyl-coenzyme A that is required for acyl-chain elongation requires the import of metabolites from the cytosol and their subsequent metabolism. Early studies had implicated acetate as the carbon source for plastidial fatty acid synthesis but more

Stephen Rawsthorne

2002-01-01

125

Some Physical Properties of Compressed Gases. VI. The Fugacity of Carbon Dioxide  

Microsoft Academic Search

The Michels' compressibility data for carbon dioxide are smoothed and interpolated by graphical methods, and the fugacity is computed at certain integral pressures. The temperature range is from 0 to 150C, and the pressure range from 0 to the neighborhood of 3000 atmos. Along all isotherms, the fugacity at first drops below the pressure, the ratio fp decreasing with p-a

W. Edwards Deming; Lola S. Deming

1939-01-01

126

Infrared matrix isolation studies of carbon disulfide and carbon dioxide complexes with nitrous and nitric acids  

Microsoft Academic Search

Argon matrix infrared spectra of carbon disulfide and carbon dioxide complexes with nitrous and nitric acids indicate the formation of hydrogen bonded structures. In all the studied systems, the acidic proton of the hydroxyl group interacted with the terminal atom (S or O) of the base molecule. The observed red shifts of the OH stretching mode were equal to ca.

M. Wierzejewska; M Dziadosz

1999-01-01

127

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

128

Potential effects of clean coal technologies on acid precipitation, greenhouse gases, and solid waste disposal  

SciTech Connect

The US Department of Energy`s (DOE`s) Clean Coal Technology Demonstration Program (CCTDP) was initially funded by Congress to demonstrate more efficient, economically feasible, and environmentally acceptable coal technologies. Although the environmental focus at first was on sulfur dioxide (SO{sub 2}) and nitrogen oxides (NO{sub x}) because their relationship to acid precipitation, the CCTDP may also lead to reductions in carbon dioxide (CO{sub 2}) emissions and in the volume of solid waste produced, compared with conventional technologies. The environmental effects of clean coal technologies (CCTs) depend upon which (if any) specific technologies eventually achieve high acceptance in the marketplace. In general, the repowering technologies and a small group of retrofit technologies show the most promise for reducing C0{sub 2} emissions and solid waste. These technologies also compare favorably with other CCTs in terms of SO{sub 2} and NO{sub x} reductions. The upper bound for CO{sup 2} reductions in the year 2010 is only enough to reduce global ``greenhouse`` warming potential by about 1%. However, CO{sub 2} emissions come from such variety of sources around the globe that no single technological innovation or national policy change could realistically be expected to reduce these emissions by more than a few percent. Particular CCTs can lead to either increases or decreases in the amount of solid waste produced. However, even if decreases are not achieved, much of the solid waste from clean coal technologies would be dry and therefore easier to dispose of than scrubber sludge.

Blasing, T.J.; Miller, R.L.; McCold, L.N.

1993-11-01

129

Self-recovering soot detector, particularly to monitor carbon content in diesel engine exhaust gases  

SciTech Connect

An insulating support body, for example an aluminum oxide ceramic, supports two electrodes spaced from each other by a small gap, for example 0.1 mm, which will have therebetween a high resistance. Upon collection of soot, the resistance between the electrodes across the gap will drop, which can be indicated by sensing current through the electrodes upon connection to a source of electrical energy. To remove soot upon termination of smoking, or soot contents in the gases, the electrodes are applied over, or embedded in a layer of essentially nonconducting catalyzing material which, in the presence of oxygen, catalyzes the oxidation of soot located in the gap between the electrodes to thereby remove the soot by oxidation and restore the resistance of the path between the electrodes and hence the sensitivity of the sensor for subsequent detection of accumulation of soot in the gap. Preferably, the non-conductive catalyzing material is a mixture of platinum, or a platinum metal , or a platinum metal alloy and a metal oxide which is compatible with, or identical to the ceramic base, for example aluminum oxide. The essentially electrically non-conductive layer can be applied by thick-film technology, and the electrodes also by thick-film technology thereover, or the electrodes may be in the form of fine platinum wires extending through the catalyzing electrically non-conductive layer. The sensing element can be held in a housing or socket, similar to a spark plug socket.

Sarholz, W.

1981-12-22

130

One-step synthesis of a novel carbon-based strong acid catalyst through hydrothermal carbonization  

Microsoft Academic Search

\\u000a AbstractA novel carbon-based strong acid catalyst was synthesized through the one-step hydrothermal carbonization of furaldehyde and\\u000a p-toluenesulfonic acid (PTSA) in aqueous solution at 180C for only 4h. The novel carbon-based solid acid possessed high\\u000a acidity, and the catalytic activities were investigated by esterification and oxathioketalization. The results showed that\\u000a the novel catalyst demonstrated much greater activity than the traditional solid

Huiquan Xiao; Yingxue Guo; Xuezheng Liang; Chenze Qi

2010-01-01

131

Modeling of the carbon nanotube chemical vapor deposition process using methane and acetylene precursor gases  

Microsoft Academic Search

Chemical vapor deposition of carbon nanotubes (CNTs) in a horizontal tube-flow reactor has been investigated with a fully coupled reactor-scale computational model. The model combined conservation of mass, momentum, and energy equations with gas-phase and surface chemical reactions to describe the evolution of a hydrogen and hydrocarbon feed-stream as it underwent heating and reactions throughout the reactor. Investigation was directed

Andrew C. Lysaght; Wilson K. S. Chiu

2008-01-01

132

Analysis of PD-generated SF6 decomposition gases adsorbed on carbon nanotubes  

Microsoft Academic Search

Chemical byproducts analysis has been recognized as a powerful diagnosis method for SF6 gas-insulated switchgear (GIS). The authors have previously demonstrated that a carbon nanotube (CNT) gas sensor could detect partial discharge (PD) generated in SF6 gas. However, PD-generated decomposition gas species, which were responsible for the CNT gas sensor response, have not been identified yet. In this paper, two

Weidong Ding; Ryota Hayashi; Kohei Ochi; Junya Suehiro; Kiminobu Imasaka; Masanori Hara; Noriaki Sano; Eiichi Nagao; Tadao Minagawa

2006-01-01

133

The effect of arterial blood sampling sites on blood gases and acid-base balance parameters in calves.  

PubMed

In 21 healthy calves, 1-6 months old, the interrelationship and comparability of acid-base balance variables (pH, HCO3-, BE) and blood gases (pCO2, pO2, and sat-O2) were evaluated in arterial blood collected from a larger, centrally localised (the a. axillaris) and a smaller peripheral artery (the a. auricularis caudalis). Sampling was done by direct puncture of the vessels without local anaesthesia. Except for blood pH, significant differences were observed in the average values of pCO2, pO2, HCO3-, sat-O2 (P < 0.001), and BE (P < 0.05). Analyses of blood from the a. axillaris showed higher pH, pO2, and sat-O2 values, and lower pCO2, HCO3-, and BE values compared with that from the a. auricularis caudalis. Despite statistically significant differences between some variables, in all indices high and significant correlation relationships were recorded (R = 0.928-0.961; P < 0.001). Therefore, from the biological and clinical point of view, these differences are unimportant and the presented method of peripheral arterial blood sampling can be considered suitable for evaluating blood gases and acid-base status. PMID:11702345

Nagy, O; Kovc, G; Seidel, H; Weissov, T

2001-01-01

134

Biomass Burning and the Production of Greenhouse Gases.  

National Technical Information Service (NTIS)

Biomass burning is a source of greenhouse gases, carbon dioxide, methane, and nitrous oxide. In addition, biomass burning is a source of chemically active gases, including carbon monoxide, nonmethane hydrocarbons, and nitric oxide. These gases, along with...

J. S. Levine

2004-01-01

135

Experimental equilibrium and modeling for the absorption of acid gases in diethanolamine solutions at low and high partial pressures  

Microsoft Academic Search

This study was undertaken to develop an experimental apparatus that would allow direct measurements of gas equilibrium solubility in aqueous alkanolamine solutions at low gas partial pressures. Carbon dioxide and hydrogen sulfide solubility in 20, 35 and 50% by weight diethanolamine aqueous solutions was measured. The measurements were made at acid gas partial pressures between 0.003 and 10.9 psia and

Elizondo-Villarreal

1989-01-01

136

Activated carbon sheet prepared from softwood acetic acid lignin  

Microsoft Academic Search

As an example of activated carbon (AC) moldings, AC sheets were prepared from thermoplastic acetic acid lignin by lamination.\\u000a The resulting AC sheets are a new type of product that can be applied as water and air cleaners. Powdered softwood acetic\\u000a acid lignin (SAL) was molded into sheets by a thermal pressing method. When the sheet was carbonized under a

Yasumitsu Uraki; Ryo Taniwatashi; Satoshi Kubo; Yoshihiro Sano

2000-01-01

137

Phosphorylated Mesoporous Carbon as a Solid Acid Catalyst  

SciTech Connect

Mesoporous carbon catalyst supports are attractive due to their wide chemical stability while potentially increasing masstransport through and providing a path for larger molecules to access catalytic sites. Herein we report the synthesis of a 10 phosphorylated mesoporous carbon solid-acid catalyst characterized by NH3-TPD and isopropanol dehydration.

Dai, Sheng [ORNL; Mayes, Richard T [ORNL; Fulvio, Pasquale F [ORNL; Ma, Zhen [ORNL

2011-01-01

138

Antimicrobial activity of kaurenoic acid derivatives substituted on carbon-15.  

PubMed

The antibacterial and antifungic activities of two kaurenic acids, ent kaurenoic acid and cinnamoylgrandifloric acid isolated from a hexane extract of aerial parts of Mikania laevigata, were investigated and compared with the activities of other kaurenic acid derivatives substituted on carbon-15. Only acetylgrandifloric acid (ent-kaur-16-en-15 alpha-acetyloxy-19-oic) and its epimer xylopic acid (ent-kaur-16-en-15 beta-acetyloxy-19-oic) displayed significant antibacterial activity at concentrations greater than or equal to 250 micrograms/ml, the 15 alpha epimer being the most active. PMID:2517587

Davino, S C; Giesbrecht, A M; Roque, N F

1989-01-01

139

Nitric acid vapor removal by activated, impregnated carbons  

SciTech Connect

Laboratory and industrial workers can be exposed to vapors of nitric acid, especially in accidents, such as spills. Nitric acid can also be a product of incineration for energy production or waste (e.g., CW agent) disposal. Activated carbons containing impregnants for enhancing vapor and gas removal have been tested for effectiveness in removing vapors of nitric acid from air. The nitric acid vapor was generated from concentrated acid solutions and detected by trapping in a water bubbler for pH measurements. Both low and moderate relative humidity conditions were used. All carbons were effective at vapor contact times representative of air-purifying respirator use. One surprising observation was the desorption of low levels of ammonia from impregnated carbons. This was apparently due to residual ammonia from the impregnation processes.

Wood, G.O.

1996-12-31

140

Separation of carbon dioxide and sulfur dioxide gases using room-temperature ionic liquid (hmim)(Tf2N)  

SciTech Connect

To understand capturing and/or enhanced gaseous selectivity of industrial flue gases containing CO{sub 2} and SO{sub 2} using room-temperature ionic liquids, we have developed a ternary equation of state (EOS) model for a CO{sub 2}/SO{sub 2}/1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ((hmim)(Tf2N)) system. The present model is based on a generic RK (Redlich-Kwong) EOS, with empirical binary interaction parameters of each binary system. These interaction parameters have been determined using our measured VLE (vapor-liquid-equilibrium) data for SO{sub 2}/(hmim)(Tf2N) and CO{sub 2}/(hmim)(Tf2N) and literature data for CO{sub 2}/SO{sub 2}. The validity of the present EOS has been checked by conducting ternary VLE experiments for the present system. With this EOS, isothermal ternary phase diagrams and solubility (VLE) behaviors have been calculated for various (T, P, and feed compositions) conditions. For large and equimolar CO{sub 2}/SO{sub 2} mole ratios, the gaseous selectivity is nearly independent of the amount of the ionic liquid addition. However, for small CO{sub 2}/SO{sub 2} mole ratios the addition of the ionic liquid significantly increases the selectivity. The strong absorption of CO{sub 2} and SO{sub 2} in this ionic liquid may be practical for the simultaneous capture of these acid gases. 39 refs., 8 figs., 4 tabs.

A. Yokozeki; Mark B. Shiflett

2009-09-15

141

Water, sulfur dioxide and nitric acid adsorption on calcium carbonate: a transmission and ATR-FTIR study.  

PubMed

Calcium carbonate (CaCO3) is a reactive component of mineral dust aerosol as well as buildings, statues and monuments. In this study, attenuated total reflection (ATR) and transmission Fourier transform infrared spectroscopy (FTIR) have been used to study the uptake of water, sulfur dioxide and nitric acid on CaCO3 particles at 296 K. Under atmospheric conditions, CaCO3 particles are terminated by a Ca(OH)(CO3H) surface layer. In the presence of water vapor between 5 and 95% relative humidity (RH), water molecularly adsorbs on the Ca(OH)(CO3H) surface resulting in the formation of an adsorbed thin water film. The adsorbed water film assists in the enhanced uptake of sulfur dioxide and nitric acid on CaCO3 in several ways. Under dry conditions (near 0% RH), sulfur dioxide and nitric acid react with the Ca(OH)(CO3H) surface to form adsorbed carbonic acid (H2CO3) along with sulfite and nitrate, respectively. Adsorbed carbonic acid is stable on the surface under vacuum conditions. Once the surface saturates with a carbonic acid capping layer, there is no additional uptake of gas-phase sulfur dioxide and nitric acid. However, upon adsorption of water, carbonic acid dissociates to form gaseous carbon dioxide and there is further uptake of sulfur dioxide and nitric acid. In addition, adsorbed water increases the mobility of the ions at the surface and enhances uptake of SO2 and HNO3. In the presence of adsorbed water, CaSO3 forms islands of a crystalline hydrate whereas Ca(NO3)2 forms a deliquescent layer or micropuddles. Thus adsorbed water plays an important and multi-faceted role in the uptake of pollutant gases on CaCO3. PMID:19791344

Al-Hosney, H A; Grassian, V H

2005-03-21

142

Use of Molecular Modeling to Determine the Interaction and Competition of Gases within Coal for Carbon Dioxide Sequestration  

SciTech Connect

A 3-dimensional coal structural model for the Argonne Premium Coal Pocahontas No. 3 has been generated. The model was constructed based on the wealth of structural information available in the literature with the enhancement that the structural diversity within the structure was represented implicitly (for the first time) based on image analysis of HRTEM in combination with LDMS data. The complex and large structural model (>10,000 carbon atoms) will serve as a basis for examining the interaction of gases within this low volatile bituminous coal. Simulations are of interest to permit reasonable simulations of the host-guest interactions with regard to carbon dioxide sequestration within coal and methane displacement from coal. The molecular structure will also prove useful in examining other coal related behavior such as solvent swelling, liquefaction and other properties. Molecular models of CO{sub 2} have been evaluated with water to analyze which classical molecular force-field parameters are the most reasonable to predict the interactions of CO{sub 2} with water. The comparison of the molecular force field models was for a single CO{sub 2}-H{sub 2}O complex and was compared against first principles quantum mechanical calculations. The interaction energies and the electrostatic interaction distances were used as criteria in the comparison. The ab initio calculations included Hartree-Fock, B3LYP, and Moeller-Plesset 2nd, 3rd, and 4th order perturbation theories with basis sets up to the aug-cc-pvtz basis set. The Steele model was the best literature model, when compared to the ab initio data, however, our new CO{sub 2} model reproduces the QM data significantly better than the Steele force-field model.

Jeffrey D. Evanseck; Jeffry D. Madura

2003-02-23

143

Intramolecular carbon isotope distribution of acetic acid in vinegar.  

PubMed

Compound-specific carbon isotope analysis of acetic acid is useful for origin discrimination and quality control of vinegar. Intramolecular carbon isotope distributions, which are each carbon isotope ratios of the methyl and carboxyl carbons in the acetic acid molecule, may be required to obtain more detailed information to discriminate such origin. In this study, improved gas chromatography-pyrolysis-gas chromatography-combustion-isotope ratio mass spectrometry (GC-Py-GC-C-IRMS) combined with headspace solid-phase microextraction (HS-SPME) was used to measure the intramolecular carbon isotope distributions of acetic acid in 14 Japanese vinegars. The results demonstrated that the methyl carbons of acetic acid molecules in vinegars produced from plants were mostly isotopically depleted in (13)C relative to the carboxyl carbon. Moreover, isotopic differences (?(13)C(carboxyl) - ?(13)C(methyl)) had a wide range from -0.3 to 18.2, and these values differed among botanical origins, C3, C4, and CAM plants. PMID:21830825

Hattori, Ryota; Yamada, Keita; Kikuchi, Makiko; Hirano, Satoshi; Yoshida, Naohiro

2011-08-18

144

Purification of wet phosphoric acid using modified activated carbon  

Microsoft Academic Search

Phosphoric acid is very important to the Tunisian economy. A new method has been developed to reduce the concentration of inorganic impurities present in commercial Tunisian phosphoric acid. This method is based on the modification of activated carbon with sodium dodecyl sulphonate to carry out the exchange of ions. The preliminary results with the column used for this purpose was

Lotfi Monser; Mohamed Ben Amor; Mohamed Ksibi

1999-01-01

145

Biosynthesis of 2-hydroxyisobutyric acid (2-HIBA) from renewable carbon  

Microsoft Academic Search

Nowadays a growing demand for green chemicals and cleantech solutions is motivating the industry to strive for biobased building blocks. We have identified the tertiary carbon atom-containing 2-hydroxyisobutyric acid (2-HIBA) as an interesting building block for polymer synthesis. Starting from this carboxylic acid, practically all compounds possessing the isobutane structure are accessible by simple chemical conversions, e. g. the commodity

Thore Rohwerder; Roland H Mller

2010-01-01

146

12-Aminododecanoic acid as a corrosion inhibitor for carbon steel  

Microsoft Academic Search

The inhibiting effect of 12-aminododecanoic acid (AA) on corrosion of carbon steel (CS) was investigated in hydrochloric acid of different pH, temperatures and over a prolonged period of time, and also in some other selected corrosive solutions. It was found that AA inhibits both partial corrosion reactions, with a slightly stronger inhibition of the anodic corrosion reaction. The corrosion protection

Saad Ghareba; Sasha Omanovic

2011-01-01

147

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, ...

148

Field evaluation of gelled acid for carbonate formations  

SciTech Connect

A new gelled acid was evaluated in the west Texas, southeast New Mexico, and Oklahoma areas. The purpose of this evaluation was to determine how successful a gelled acid, prepared from xanthan polymer, would be in several carbonate formations. Several types of acidizing techniques were employed. These treatments vary from one to nine stages, with and without diverting agents. More than 20 treatments are summarized. Production figures for the wells treated are discussed, as well as pertinent related information. 5 refs.

Church, D.C.; Quisenberry, J.L.; Fox, K.B.

1981-12-01

149

Geochemical monitoring of the 20022003 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 20022003 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

150

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

Code of Federal Regulations, 2013 CFR

...contained in the gases discharged to the atmosphere from a designated facility is 27 milligrams...contained in the gases discharged to the atmosphere from a designated facility is 25 milligrams...exhibited by the gases discharged to the atmosphere from a designated facility is 10...

2013-07-01

151

Fragrance material review on carbonic acid, methyl phenylmethyl ester.  

PubMed

A toxicologic and dermatologic review of carbonic acid, methyl phenylmethyl ester when used as a fragrance ingredient is presented. Carbonic acid, methyl phenylmethyl ester is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for carbonic acid, methyl phenylmethyl ester were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414647

McGinty, D; Letizia, C S; Api, A M

2012-03-04

152

Helium and carbon isotope systematics of Rungwe geothermal gases and fluids; southern Tanzania  

NASA Astrophysics Data System (ADS)

P. H. BARRY1*, D. R. HILTON1, T. P. FISCHER2, J. M. DE MOOR2, F. MANGASINI3 C. RAMIREZ4 1 Geosciences Research Division, Scripps Institution of Oceanography, UCSD, La Jolla, California 92093-0244, USA (*Correspondence: pbarry@ucsd.edu) 2 Department of Earth and Planetary Sciences, MSC 03 2040, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, USA. 3 Department of Mining and Mineral Processing Engineering, University of Dar Es Salaam, PO Box 35131, Dar Es Salaam, Tanzania. 4 Centro de Investigaciones en Ciencias Geologicas, Escuela Centroamericana de Geologia, Universidad de Costa Rica. The East African Rift (EAR) is the largest modern example of continental rifting, extending from the Afar depression in the north to the Rungwe region in southern Tanzania. EAR volcanism is attributed to the presence of one or more mantle plumes [1]. Late Miocene to recent volcanism and geothermal activity mark the Rungwe region [2], with mafic eruptions as recently as 200 years ago. Our aim is to delineate the southern geographical extent of plume influence on the propagating EAR by investigating the He-CO2 characteristics of geothermal fluids in the Rungwe region. We report new helium (He) and carbon (C) isotopes (3He/4He, ?13C) and relative abundance (CO2/3He) characteristics for a suite of 20 geothermal gas and fluid samples from 11 different localities in the Rungwe region. He-isotopes are in good agreement with previous reports [3], and range from ~1 RA to ~7 RA (MORB-like values), indicating admixture between upper mantle He and variable proportions of radiogenic He. C-isotopes ranges from -2.8 to -6.5 (vs. PDB) with all falling in the MORB range (~4.5 2). CO2/3He ratios vary over 5 orders of magnitude from ~3 x 10^9 (MORB-like) to higher values (up to ~3 x 10^13) normally associated with crustal lithologies. Taken together, the He-CO2 data can be explained by 2-component mixing of a deep-seated mantle source with crustal component(s). There are no observed latitudinal isotopic trends in He-CO2. However, the two localities with MORB-like 3He/4He ratios ~6 to 7 RA, ?13C ~ -4 to -5 and CO2/3He ~ 4 x10^9 are both cold temperature (~ 15C) CO2 gas vents. The MORB-like characteristics of these cold vents are comparable to MORB-like values observed at Oldoinyo Lengai in northern Tanzania [4], suggesting that both Rungwe region and Oldoinyo Lengai may derive their volatile compositions from a homogeneous (MORB-like) mantle source common to the entire segment of the southern EAR. [1] Furman (2007) Journal of African Earth Sciences 48, 147-160. [2] Ebinger et al. (1989) Journal of Geophysical Research 94, 15,785-15,803. [3] Pik et al. (2006) Chemical Geology 226, 100-114. [4] Fisher et al. (2009) Nature 459, 77-80.

Barry, P. H.

2009-12-01

153

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,...

154

Carbonic Acid: From Polyamorphism to Polymorphism  

Microsoft Academic Search

Layers of glassy methanolic (aqueous) solutions of KHCO3 and HCl were deposited sequentially at 78 K on a CsI window, and their reaction on heating in vacuo in steps from 78 to 230 K was followed by Fourier transform infrared (FTIR) spectroscopy. After removal of solvent and excess HCl, IR spectra revealed formation of two distinct states of amorphous carbonic

Katrin Winkel; Wolfgang Hage; Thomas Loerting; Sarah L. Price; Erwin Mayer

2007-01-01

155

Activated carbon from cotton stalks by impregnation with phosphoric acid  

Microsoft Academic Search

Dried, crushed cotton stalks were impregnated with varying concentrations of phosphoric acid (2085 wt.%), dried at 383 K and carbonized at 773 K for 2 h. Porosity was determined by analysis of N2\\/77 K adsorption isotherms. High adsorbing carbons with well developed mesoporosity were obtained. Analysis for microporosity, by the ?S-method, proved the presence of minor content in all products.

Badie S Girgis; Mona F Ishak

1999-01-01

156

Effect of Acid Gases on the Pigment Composition of the Leaves of Trees and Lawn Plants (Vliyanie Kislykh Gazov na Pigmentnyi Sostav Listev Drevesnykh i Gazonykh Rastenii).  

National Technical Information Service (NTIS)

The chlorophyll a and b, carotene, lutein, violaxanthin, and neoxanthin contents in the leaves of plants, subjected during various phases of their growth and development to acid gases such as SO2, NO2, F, HF, and P2O5 in various concentrations, were studi...

V. V. Suslova V. S. Nikoloevskii

1971-01-01

157

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...

158

Equilibrium solubility of acid gases in diethanolamine and monoethanolamine solutions at low partial pressures  

Microsoft Academic Search

Aqueous monoethanolamine (MEA) and diethanolamine (DEA) solutions are used extensively for the removal of HS and CO from gas streams. Advantages of the use of these particular chemical solvents include high reactivity, low cost, ease of reclamation, low absorption of hydrocarbons, and relatively high capacity at low acid gas partial pressures. The rational design and operation of MEA and DEA

D. Lal; E. E. Isaacs; A. E. Mather; F. D. Otto

1980-01-01

159

Molecular Beam Studies of Reactions of Protic Gases with Bare and Surfactant-Coated Sulfuric Acid.  

National Technical Information Service (NTIS)

Gas-liquid scattering experiments were used to investigate the uptake of HCl and HBr, the evaporation of water, and the hydrolysis of N2O5 in sulfuric acid coated with the soluble surfactants n-butanol and n-hexanol under atmospheric conditions. The exper...

G. M. Nathanson

2007-01-01

160

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.

Pfanz, Hardy; Heber, Ulrich

1986-01-01

161

Separation and identification of carboxylic acids in MALT samples from the headspace gases in Hanford tank 103C  

SciTech Connect

Samples of headspace gases from Westinghouse Hanford Company (WHC) waste storage tank 103C were analyzed by gas chromatography/mass spectrometry by Pacific Northwest Laboratory staff. The samples were obtained using a cryo-trap sampler designed by WHC and known as the Mobile Analytical Laboratory Trap (MALT). The samples, which were obtained in September 1989, were available in large amounts (200 mi). The specific targets for this analysis were n-butyric, i-butyric, n-valeric, and i-valeric organic acids. Of the acids targeted, only n-butyric was found, and only trace amounts of it were detected with a detection limit below 1 ppM in the extract. The levels found were so low as to cause difficulty in quantitation. All concentrations reported here are for the methanol extract solutions and not the concentrations in the headspace of tank 103C. To calculate concentrations in the headspace, the MALT sampling volume and the methanol rinse volume must be obtained from the MALT personnel at WHC.

Clauss, S.A.; Lucke, R.B.

1993-08-01

162

Analysis of Commercial Cylinder Gases of Nitric Oxide, Sulfur Dioxide, and Carbon Monoxide at Source Concentrations: Results of Audit 5.  

National Technical Information Service (NTIS)

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 ...

C. E. Decker W. C. Eaton R. C. Shores C. V. Wall

1981-01-01

163

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 N 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

164

Variability of blood gases, pulse oximeter saturation, and end-tidal carbon dioxide pressure in stable, mechanically ventilated trauma patients  

Microsoft Academic Search

We evaluated the short-term variability of Pao2, Paco2, pulse oximeter saturation (Spo2), and end-tidalPco2 (Petco2) in mechanically ventilated trauma patients. All patients were stable and undisturbed during the evaluation periods. Blood gases were obtained from an arterial catheter 4 times at 20-minute intervals.Spo2 andPetco2 were recorded when the blood gases were obtained. Fifty evaluations were made in 26 patients; 24

Dean Hess; Nikhileshwer N. Agarwal

1991-01-01

165

Carbon--oxygen--hydrogen--sulfur gaseous system. III. Magmatic gases compatible with oxides and sulfides in basaltic magmas  

Microsoft Academic Search

The interaction of magma-gas systems was investigated, employing fugacity data derived from mineral equilibrium in basaltic lavas. These data were compared with equilibrium composition in the C-O-H-S gaseous system to identify atomic and molar composition of gases compatible with lavas over a range of physical conditions. The atmospheric compositions of gases compatible with pyrrhotite-magnetite assemblages crystallized from immiscible sulfide liquids

T. M. Gerlach; B. E. Nordlie

1975-01-01

166

Unusual stability and carbon acidity of a dicationic carbon species.  

PubMed

1,1'-Methylenebis(pyridinium) dication (MDP) is an unusual ion with two formal positively charged substituents attached to a central carbon, yet it is remarkably stable to hydrolysis at pH < 8. However, above this pH it undergoes a biphasic reaction liberating two equiv of pyridine sequentially. The rate of the first phase is second order in hydroxide ion, while that of the second is pH-independent. The first phase is also accompanied by the generation of a chromophore at 366 nm, which has been identified as a pyridine-ring-opened unsaturated iminoaldehyde formed by an ANRORC-type mechanism. This intermediate then undergoes ring closure to give the second equiv of pyridine and formaldehyde. Below pD 8 there is a very slow alternative pathway for degradation that is first order in hydroxide ion, liberates only one equiv of pyridine, and forms N-(hydroxymethyl)pyridinium ion. Deuterium exchange of the central methylene in D2O is faster than the breakdown of MDP and is predominantly OD(-)-catalyzed with a small amount of buffer catalysis. The estimated pKa of MDP dication in H2O, 21.2 at 25 C and I = 1.0 M (KCl), is unexpectedly high but is about 9 units lower than that for the monocationic N-methylpyridinium ion. Deuterium exchange also occurs at the 2 and 6 positions of the pyridinium rings, but at a lower rate that is first order in deuteroxide ion and competitive with the breakdown of MDP only below pD 11. PMID:24059810

Mistry, Dharmit; Powles, Nicholas; Page, Michael I

2013-10-10

167

Method to improve matrix acidizing in carbonates  

SciTech Connect

This patent describes a method for increasing the permeability of a formation which formation has a least one zone of lesser permeability and one zone of greater permeability where high energy impulse fracturing is used to combination with an inhibited acid. It comprises: directing into a wellbore within the formation a pumpable solidifiable gel into a zone of the formation having a greater permeability under conditions to selectively close pores in the greater permeability zone.

Jennings, A.R. Jr.; Jones, L.G.; Shu, P.

1990-04-17

168

A mechanistic model of wormhole growth in carbonate matrix acidizing and acid fracturing  

SciTech Connect

A mathematical model that describes the growth and competition of wormholes during ann acidizing treatment in a carbonate formation was developed. The model is initialized with the distribution of largest pores. Wormhole characteristics (size, length, and distribution) were found too be controlled by acid-injection, diffusion, and fluid-loss rates.

Hung, K.M.; Hill, A.D.; Sepehrnoorl, K.

1989-01-01

169

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...

170

Carbon flux and fatty acid synthesis in plants.  

PubMed

The de novo synthesis of fatty acids in plants occurs in the plastids through the activity of fatty acid synthetase. The synthesis of the malonyl-coenzyme A that is required for acyl-chain elongation requires the import of metabolites from the cytosol and their subsequent metabolism. Early studies had implicated acetate as the carbon source for plastidial fatty acid synthesis but more recent experiments have provided data that argue against this. A range of cytosolic metabolites including glucose 6-phosphate, malate, phosphoenolpyruvate and pyruvate support high rates of fatty acid synthesis by isolated plastids, the relative utilisation of which depends upon the plant species and the organ from which the plastids are isolated. The import of these metabolites occurs via specific transporters on the plastid envelope and recent advances in the understanding of the role of these transporters are discussed. Chloroplasts are able to generate the reducing power and ATP required for fatty acid synthesis by capture of light energy in the reactions of photosynthetic electron transport. Regulation of chloroplast fatty acid synthesis is mediated by the response of acetyl-CoA carboxylase to the redox state of the plastid, which ensures that the carbon metabolism is linked to the energy status. The regulation of fatty acid synthesis in plastids of heterotrophic cells is much less well understood and is of particular interest in the tissues that accumulate large amounts of the storage oil, triacylglycerol. In these heterotrophic cells the plastids import ATP and oxidise imported carbon sources to produce the required reducing power. The sequencing of the genome of Arabidopsis thaliana has now enabled a number of aspects of plant fatty acid synthesis to be re-addressed, particularly those areas in which in vitro biochemical analysis had provided equivocal answers. Examples of such aspects and future opportunities for our understanding of plant fatty acid synthesis are presented and discussed. PMID:11755683

Rawsthorne, Stephen

2002-03-01

171

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

Code of Federal Regulations, 2013 CFR

...shall cause to be discharged into the atmosphere from that affected facility any gases...shall cause to be discharged into the atmosphere from that affected facility any gases...shall cause to be discharged into the atmosphere from that affected facility any...

2013-07-01

172

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

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

173

Arterial blood gases, acid-base balance, and lactate and gas exchange variables during hypoxic exercise.  

PubMed

To determine the effect of hypoxia on lactate threshold (LT), onset of blood lactate accumulation (OBLA), and gas exchange threshold (GET), the lactate level together with VO2, VCO2, VE, and acid-base status in arterial blood from 12 female distance runners performing a progressive incremental treadmill test under the condition of hypoxic gas inhalation (HC: FIO2 is 16.0% in N2) compared with normoxic conditions (NC: FIO2 is 20.9%; i.e., air) were examined. During exercise, HC shifted LT, GET, and OBLA to a lower VO2 by 12.5%, 12.9%, and 9.3%, respectively. The GET during hypoxic exercise was well correlated with LT (GET = 0.973LT + 0.04; expressed in VO2 l.min-1). The close reciprocal changes in arterial blood lactate and bicarbonate (HCO3-) were observed during hypoxic as well as normoxic exercise. These findings provide evidence for the cause and effect relationship between LT and GET, even in hypoxic exercise. During submaximal exercise below the LT, PaCO2 and HCO3- slightly increased both in NC and HC with pH remaining unchanged. However, during exercise above the LT, the PaCO2, HCO3-, and pH all decreased with pH decreasing more markedly during hypoxia. In conclusion, this study demonstrated a clear increase in arterial lactate during hypoxic exercise above the LT. Both the LT and GET are shifted to a lower work rate by hypoxia in the same manner with the correlation between them remaining high, supporting the cause and effect relationship of these two parameters. PMID:2514152

Yoshida, T; Udo, M; Chida, M; Makiguchi, K; Ichioka, M; Muraoka, I

1989-08-01

174

Process for Producing Catalysts for Cleaning Industrial-Waste Gases.  

National Technical Information Service (NTIS)

This invention concerns catalysts which are effective for removing nitrogen oxides (NO/sub x/), carbon monoxide (CO) and hyrocarbons (HC) from automobile exhaust gases, waste gases from fixed combustion systems and waste gases from chemical plants. The pr...

I. Shimizu K. Abe

1983-01-01

175

Effect of Carbon4 and Carbon5 Volatile Fatty Acids on Digestion of Plant Cell Wall In Vitro1  

Microsoft Academic Search

When mixed ruminal bacteria were incubated in an artificial medium with isolated plant cell wails, cell wall diges- tion and ammonia utilization were increased by low concentrations (< .30 mM) of carbon-4 and carbon-5 volatile fatty acids (isobutyric, isovaleric, valeric, and 2-methylbutyric). Carbon-4 and carbon-5 acid supplementation also in- creased cell wall digestion of intact forages. No pattern was observed

A. R. Gorosito; J. B. Russell; P. J. Van Soest

1985-01-01

176

Influence of different gases used for laparoscopy (helium, carbon dioxide, room air, xenon) on tumor volume, proliferation, and apoptosis  

Microsoft Academic Search

Background: Previous reports suggest that helium pneumoperitoneum used for laparoscopic surgery suppresses postoperative tumor growth. The present study was designed to determine the effects of gases used in laparoscopy on tumor volume, proliferation, and apoptosis in rats with implanted malignoma. Methods: In 36 rats Morris hepatoma 3294A cells were implanted intrahepatically. Then, after 5 days, they underwent laparoscopy using helium

S. Dhn; P. Schwalbach; F. Whleke; A. Benner; C. Kuntz

2003-01-01

177

A Comparative Structural Study of Cracking Catalyst, Porous Glass, and Carbon Plugs by Surface and Volume Flow of Gases  

Microsoft Academic Search

Transient and steady states of volume and surface flow of gases and vapours in microporous media require for their description four different diffusion coefficients, namely, a surface and a gas-phase coefficient for transient and a surface and gas-phase coefficient for steady flow. The distinction between steady and transient flow arises in part because of the role of blind pores. Similarly,

R. M. Barrer; T. Gabor

1959-01-01

178

A comparison of blood gases and acid-base measurements in arterial, arterialized venous, and venous blood during short-term maximal exercise  

Microsoft Academic Search

SummaryThe purpose of this study was to determine the relationship between blood gases and acid-base measurements in arterial, arterialized venous, and venous blood measured simultaneously during short-term maximal exercise. Ten well-trained male cyclists performed a graded maximal exercise test on a cycle ergometer to determine the power output corresponding to their peak oxygen consumption (test I), and a short-term maximal

Jon Linderman; Thomas D. Fahey; Gregory Lauten; Alan S. Brooker; Doug Bird; Bill Dolinar; Jackie Musselman; Scott Lewis; Larry Kirk

1990-01-01

179

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...

180

Carbonate-containing apatite (CAP) synthesis under moderate conditions starting from calcium carbonate and orthophosphoric acid.  

PubMed

The synthesis of carbonate-containing apatite (CAP) from calcium carbonate and orthophosphoric acid under moderate conditions was investigated. In all cases, complete precipitation of orthophosphate species was observed. The reaction temperature influenced strongly the decomposition of calcium carbonate and therefore the composition of formed products. The reaction temperature of 80 C was found to be effective for the complete decomposition of calcium carbonate particles after 48 h of reaction. Infra-red spectroscopy (IR), nuclear magnetic resonance (NMR), thermogravimetry/mass spectroscopy (TG-MS) coupling, and X-ray diffraction (XRD) characterizations allowed the identification of the composition of formed products. By increasing the reaction temperature from 20 C to 80 C, the content of A-type CAP increased and that of B-type CAP decreased, according to the favorable effect of temperature on the formation of A-type CAP. The total amount of carbonate content incorporated in CAP's structure, which was determined by TG-MS analysis, increased with the reaction temperature and reached up to 4.1% at 80 C. At this temperature, the solid product was mainly composed of apatitic components and showed the typical flat-needle-like structure of CAP particles obtained in hydrothermal conditions. These results show an interesting one-step synthesis of CAP from calcium carbonate and orthophosphoric acid as low cost but high purity starting materials. PMID:23623121

Pham Minh, Doan; Tran, Ngoc Dung; Nzihou, Ange; Sharrock, Patrick

2013-03-23

181

Voluntary Reporting of Greenhouse Gases  

EIA Publications

The Voluntary Reporting of Greenhouse Gases Program established a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., can report to the EIA, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

Information Center

2011-02-01

182

Synthesis and acid catalysis of cellulose-derived carbon-based solid acid  

Microsoft Academic Search

SO3H-bearing amorphous carbon, prepared by partial carbonization of cellulose followed by sulfonation in fuming H2SO4, was applied as a solid catalyst for the acid-catalyzed hydrolysis of ?-1,4 glucan, including cellobiose and crystalline cellulose. Structural analyses revealed that the resulting carbon material consists of graphene sheets with 1.5mmolg?1 of SO3H groups, 0.4mmolg?1 of COOH, and 5.6mmolg?1 of phenolic OH groups. The

Satoshi Suganuma; Kiyotaka Nakajima; Masaaki Kitano; Daizo Yamaguchi; Hideki Kato; Shigenobu Hayashi; Michikazu Hara

2010-01-01

183

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.

Szarek, Stan R.; Troughton, John H.

1976-01-01

184

Using DFT analysis of adsorption data of multiple gases including H 2 for the comprehensive characterization of microporous carbons  

Microsoft Academic Search

Hydrogen and nitrogen adsorption isotherms at cryogenic temperatures (77 and 87K) were used to characterize the microporosity of a series of activated carbons, representing various pore size distributions (PSD). The PSD for each carbon was calculated by simultaneous fitting of the DFT model isotherms to their experimental counterparts. The resulting PSD represents robust characteristics of the carbon structure that is

J. Jagiello; C. O. Ania; J. B. Parra; L. Jagiello; J. J. Pis

2007-01-01

185

Activated carbon passes tests for acid-gas cleanup  

Microsoft Academic Search

Use of activated carbon to remove hydrocarbon contaminants from the acid-gas feed to Claus sulfur-recovery units has been successfully pilot tested in Saudi Arabia. Pilot plant results are discussed here along with issues involved in scale-up to commercial size. Heavy hydrocarbons, particularly benzene, toluene, and xylene (BTX) have been linked to coke formation and catalyst deactivation in Claus converters. This

L. G. Harruff; S. J. Bushkuhl

1996-01-01

186

Nitric acid oxidation of vapor grown carbon nanofibers  

Microsoft Academic Search

Vapor grown carbon nanofibers (Pyrograf III) with 100300 nm diameters and ?10100 ?m lengths were oxidized in 6971 wt.% nitric acid (115 C) for various times (10 min to 24 h). These fibers were remarkably oxidation-resistant. XPS (O1s) showed that the surface atomic oxygen percent increased from 6.3 to 18.322.5% for 1090 min oxidations followed by a drop to 1415%

Priya V. Lakshminarayanan; Hossein Toghiani; Charles U. Pittman Jr.

2004-01-01

187

Intercalation of formic acid into carbon fibers and their exfoliation  

Microsoft Academic Search

Intercalation of formic acid in a mesophase-pitch-based fibers was successfully carried out by electrolysis in 50% solution. The formation of intercalation compounds was confirmed by X-ray diffraction (XRD), which showed a broad peak at the interlayer spacing of 0.92nm. By rapid heating of the intercalated compounds of carbon fibers thus produced up to 1000C, exfoliation was occurred instantaneously. Changes of

M Toyoda; J Sedlacik; M Inagaki

2002-01-01

188

Acetylene-mediated alkylation of monoalkyl carbonates and carbamic acids with tert-amines  

SciTech Connect

Carbonic acid diesters and carbamic acid esters are useful organic substances as intermediates for the syntheses of several chemicals. They are currently synthesized in industry using the processes based on phosgene or carbon monoxide. On the other hand, since carbon dioxide is an abundant and cheap carbonyl carbon source, and is much less toxic than those raw materials, substantial efforts have been focused on its fixation into carbonyl compounds including carbonic acid diesters and carbamic acid esters. However, their syntheses based on carbon dioxide reported so far require rather expensive substrates like alkyl halides, and are not competitive with the currently adopted industrial processes.

Sasaki, Yoshiyuki [National Institute for Resources and Environment, Onogawa, Tsukuba-shi (Japan)

1996-12-31

189

Butyric acid esterification kinetics over Amberlyst solid acid catalysts: the effect of alcohol carbon chain length.  

PubMed

The liquid phase esterification of butyric acid with a series of linear and branched alcohols is examined. Four strong cation exchange resins, Amberlyst 15, Amberlyst 36, Amberlyst BD 20, and Amberlyst 70, were used along with para-toluenesulfonic acid as a homogeneous catalyst. The effect of increasing alcohol carbon chain length and branching on esterification rate at 60C is presented. For all catalysts, the decrease in turnover frequency (TOF) with increasing carbon chain length of the alcohol is described in terms of steric hindrance, alcohol polarity, and hydroxyl group concentration. The kinetics of butyric acid esterification with 2-ethylhexanol using Amberlyst 70 catalyst is described with an activity-based, pseudo-homogeneous kinetic model that includes autocatalysis by butyric acid. PMID:23380294

Pappu, Venkata K S; Kanyi, Victor; Santhanakrishnan, Arati; Lira, Carl T; Miller, Dennis J

2012-12-20

190

Selective esterification of non-conjugated carboxylic acids in the presence of conjugated or aromatic carboxylic acids over active carbon supported methanesulfonic acid  

Microsoft Academic Search

Non-conjugated carboxylic acids are selectively esterified in good yields in the presence of conjugated or aromatic carboxylic\\u000a acids by stirring over active carbon supported methanesulfonic acid in dichloromethane at room temperature.

ZeWang Feng; XinQi Zhao; Hua Bi

2008-01-01

191

Biosynthesis of 2-hydroxyisobutyric acid (2-HIBA) from renewable carbon  

PubMed Central

Nowadays a growing demand for green chemicals and cleantech solutions is motivating the industry to strive for biobased building blocks. We have identified the tertiary carbon atom-containing 2-hydroxyisobutyric acid (2-HIBA) as an interesting building block for polymer synthesis. Starting from this carboxylic acid, practically all compounds possessing the isobutane structure are accessible by simple chemical conversions, e. g. the commodity methacrylic acid as well as isobutylene glycol and oxide. During recent years, biotechnological routes to 2-HIBA acid have been proposed and significant progress in elucidating the underlying biochemistry has been made. Besides biohydrolysis and biooxidation, now a bioisomerization reaction can be employed, converting the common metabolite 3-hydroxybutyric acid to 2-HIBA by a novel cobalamin-dependent CoA-carbonyl mutase. The latter reaction has recently been discovered in the course of elucidating the degradation pathway of the groundwater pollutant methyl tert-butyl ether (MTBE) in the new bacterial species Aquincola tertiaricarbonis. This discovery opens the ground for developing a completely biotechnological process for producing 2-HIBA. The mutase enzyme has to be active in a suitable biological system producing 3-hydroxybutyryl-CoA, which is the precursor of the well-known bacterial bioplastic polyhydroxybutyrate (PHB). This connection to the PHB metabolism is a great advantage as its underlying biochemistry and physiology is well understood and can easily be adopted towards producing 2-HIBA. This review highlights the potential of these discoveries for a large-scale 2-HIBA biosynthesis from renewable carbon, replacing conventional chemistry as synthesis route and petrochemicals as carbon source.

2010-01-01

192

Hydrolytic decarboxylation of carboxylic acids and the formation of protonated carbonic acid.  

PubMed

Acid-catalyzed decarboxylation reactions of carboxylic acids should avoid formation of protonated carbon dioxide, a very high energy species. A potential alternative route parallels ester hydrolysis, with addition of water to the carboxyl group followed by protonation of the unsaturated leaving group and formation of protonated carbonic acid, a species that had been predicted to be a viable reaction intermediate. The hydrolytic mechanism for the decarboxylation of pyrrole-2-carboxylic acid is consistent with observed (12)C/(13)C kinetic isotope effects (1.010 +/- 0.001 at H(0) = -0.01 and 1.043 +/- 0.001 at H(0) = -2.6), solvent kinetic isotope effects (k(H(2))(O)/k(D(2))(O) = 2 at H(0) = 0.9; k(H(2))(O)/k(D(2))(O) = 1 at H(0) = -2.9), and activation parameters [DeltaH() = 23.5 kcal.mol(-1) and DeltaS() = 5.5 cal.deg(-1).mol(-1) at H(0) = -2.9]. Thus, the specific route for a decarboxylation process is a consequence of the nature of the potential carbanion (or its conjugate acid), the acidity of the medium and avoidance of formation of protonated carbon dioxide. PMID:20121187

Mundle, Scott O C; Lacrampe-Couloume, Georges; Lollar, Barbara Sherwood; Kluger, Ronald

2010-02-24

193

Greenhouse Gases  

MedlinePLUS

... support life as we know it. Without the greenhouse effect, the average temperature of the Earth would be ... regulated independently of its warming effects. More about greenhouse gases effect on the climate Also on Energy Explained Energy ...

194

Carbon Dioxide Information Analysis Center and World Data Center-A for Atmospheric Trace Gases catalog of databases and reports  

Microsoft Academic Search

Data products and reports made available by the US Department of Energy's (DOE) Environmental Sciences Division, Office of Biological and Environmental Research (OBER), and the Carbon Dioxide Information Analysis Center (CDIAC) provide coverage in a number of areas relevant to the greenhouse effect and global climate change. Such areas include records of the concentration of carbon dioxide and other radiatively

Burtis

1998-01-01

195

Removal of Particles and Acid Gases (SO2 or HCl) with a Ceramic Filter by Addition of Dry Sorbents  

SciTech Connect

The present investigation intends to add to the fundamental process design know-how for dry flue gas cleaning, especially with respect to process flexibility, in cases where variations in the type of fuel and thus in concentration of contaminants in the flue gas require optimization of operating conditions. In particular, temperature effects of the physical and chemical processes occurring simultaneously in the gas-particle dispersion and in the filter cake/filter medium are investigated in order to improve the predictive capabilities for identifying optimum operating conditions. Sodium bicarbonate (NaHCO{sub 3}) and calcium hydroxide (Ca(OH){sub 2}) are known as efficient sorbents for neutralizing acid flue gas components such as HCl, HF, and SO{sub 2}. According to their physical properties (e.g. porosity, pore size) and chemical behavior (e.g. thermal decomposition, reactivity for gas-solid reactions), optimum conditions for their application vary widely. The results presented concentrate on the development of quantitative data for filtration stability and overall removal efficiency as affected by operating temperature. Experiments were performed in a small pilot unit with a ceramic filter disk of the type Dia-Schumalith 10-20 (Fig. 1, described in more detail in Hemmer 2002 and Hemmer et al. 1999), using model flue gases containing SO{sub 2} and HCl, flyash from wood bark combustion, and NaHCO{sub 3} as well as Ca(OH){sub 2} as sorbent material (particle size d{sub 50}/d{sub 84} : 35/192 {micro}m, and 3.5/16, respectively). The pilot unit consists of an entrained flow reactor (gas duct) representing the raw gas volume of a filter house and the filter disk with a filter cake, operating continuously, simulating filter cake build-up and cleaning of the filter medium by jet pulse. Temperatures varied from 200 to 600 C, sorbent stoichiometric ratios from zero to 2, inlet concentrations were on the order of 500 to 700 mg/m{sup 3}, water vapor contents ranged from zero to 20 vol%. The experimental program with NaHCO{sub 3} is listed in Table 1. In addition, model calculations were carried out based on own and published experimental results that estimate residence time and temperature effects on removal efficiencies.

Hemmer, G.; Kasper, G.; Wang, J.; Schaub, G.

2002-09-20

196

Carbon nanotubes and nucleic acids: tools and targets  

NASA Astrophysics Data System (ADS)

Nucleic acids are playing an important role in the rapid development of nanotechnologies. Our Editor's Choice [1] discusses the use of nucleic acids to disperse and sort single walled carbon nanotubes (SWNTs). The cover picture shows a two-dimensional photoluminescence (PL) spectrum of highly purified (6,5) SWNT:DNA hybrids. The fine resolution of the PL peaks displays photo-excited intermediates in a range of energies between ES22 and ES11 transitions revealing for the first time specific phonon-assisted optical absorption and energy relaxation mechanisms.The first author, Bibiana Onoa, has been working on carbon nanotubes and nucleic acids in the molecular electronics group of Dupont Central Research and Development. Her current research focuses on the development of nanotechnologies that allow fast and economical detection of pathogens.This special issue of physica status solidi (a) presents representative contributions and main topics on Trends in Nanotechnology from the TNT2005 International Conference in Oviedo (Spain).

Onoa, Bibiana; Zheng, Ming; Dresselhaus, Mildred S.; Diner, Bruce A.

2006-05-01

197

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 Kalancho 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.

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

1985-01-01

198

[Denitrification using polylactic acid as solid carbon source].  

PubMed

Polylactic acid (PLA) was used as solid carbon source and biofilm support simultaneously, to investigate the applicability of PLA in the denitrification process. The effect of temperature on denitrification performance was also studied. The IR analysis and SEM observation were performed to investigate the PLA surface structure and biofim morphology. The results showed that when the initial concentration of nitrate nitrogen was 50 mg/L and the temperature was 30 degrees C, the average denitrification rate was 2.6 x 10(-1) mg/(g x h) and nitrate could be completely removed within 13h. Temperature had a significant influence on the denitrification rate. The IR analysis and SEM observation of PLA surface structure confirmed the feasibility of PLA as solid carbon source. The SEM observation of biofim showed that the biofilm was thin and mainly consisted of cocci. PMID:19799294

Fan, Zhen-xing; Wang, Jian-long

2009-08-15

199

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

200

Oxidation-resistant acidic resins prepared by partial carbonization as cocatalysts in synthesis of adipic acid.  

PubMed

The oxidation-resistant acidic resins are of great importance for the catalytic oxidation systems. In this paper, the oxidatively stable acidic resins are obtained from the cation ion exchange resins (CIERs) through the thermal treatment in N(2) atmosphere. The structure and properties of the thermally treated CIERs were characterized by chemical analysis, Fourier transform infrared (FT-IR) spectra, acid capacity measurement and scanning electron microscope (SEM). The thermally treated CIERs possess high acid capacity up to 4.09 mmol g(-1). A partial carbonization is observed in the thermal treatment process of CIERs, but the morphology of resin spheres maintains well. The as-prepared CIERs are used as solid acids to assist the hydrogen peroxide oxidation of cyclohexene to adipic acid (ADA) with tungstic acid as the catalyst precursor. The improved yields of ADA in the recycling reaction are obtained in the presence of acidic CIERs. Meanwhile, the unproductive decomposition of H(2)O(2) is effectively suppressed. The high yields of ADA (about 81%) are kept by the thermally treated CIERs even after the fifth cycle. The thermally treated CIERs exhibit excellent acid-catalytic performance and possess remarkable oxidation-resistant capability. PMID:22775061

Wei, Huijuan; Li, Hongbian; Liu, Yangqing; Jin, Peng; Wang, Xiangyu; Li, Baojun

2012-07-20

201

Carbonate interlayered hydrotalcites-enhanced peroxynitrous acid chemiluminescence for high selectivity sensing of ascorbic acid.  

PubMed

In this study, Mg-Al-carbonate layered double hydroxides (denoted as Mg-Al-CO(3) LDHs) were found to catalyze the chemiluminescence (CL) emission from peroxynitrous acid (ONOOH). The enhanced CL signals resulted from the concentration of peroxynitrite (ONOO(-)) onto the LDHs surface by electrostatic attraction, meaning that ONOO(-) can interact with the intercalated carbonate easily and effectively. Moreover, ascorbic acid can react with ONOO(-), or its decomposition products (e.g., ?OH and ?NO(2)), resulting in a decrease in the CL intensity from the Mg-Al-CO(3) LDHs-catalyzed ONOOH reaction. Based on these findings, a sensitive, selective and rapid CL method was developed for the determination of ascorbic acid using Mg-Al-CO(3) LDHs-catalyzed ONOOH as a novel CL system. The CL intensity was proportional to the concentration of ascorbic acid in the range from 5.0 to 5000 nM. The detection limit (S/N = 3) was 0.5 nM and the relative standard deviation (RSD) for nine repeated measurements of 0.1 ?M ascorbic acid was 2.6%. This method has been successfully applied to determine ascorbic acid in commercial liquid fruit juices with recoveries of 97-107%. This work is not only of importance for a better understanding of the unique properties of LDHs-catalyzed CL but also of great potential for extensive applications in many fields, such as luminescence devices, bioanalysis, and labeling probes. PMID:22382556

Wang, Zhihua; Teng, Xu; Lu, Chao

2012-03-02

202

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

203

Carbon isotope fractionation in phospholipid fatty acid biomarkers of bacteria and fungi native to an acid mine drainage lake  

Microsoft Academic Search

This study identifies isotope signatures associated with autotrophic and heterotrophic microbial communities that may provide a means to determine carbon cycling relationships in situ for acid mine drainage (AMD) sites. Stable carbon isotope ratios (?13C) of carbon sources, bulk cells, and membrane phospholipids (PLFA) were measured for autotrophic and heterotrophic microbial enrichment cultures from a mine tailings impoundment in northern

Benjamin R. Cowie; Gregory F. Slater; Luc Bernier; Lesley A. Warren

2009-01-01

204

Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by boiling in sulfuric acid solution. Various analytical techniques such as TGA/DSC, Raman spectroscopy, SEM, HRTEM and EDAX were employed to investigate the morphology, graphitization and quality of the carbon nanotubes. The obtained results reveal the molarity of sulfuric acid and immersed time of the carbon nanotubes in the acid solution is very effective at purifying multi-walled carbon nanotubes. It was also found that 5 M concentration of boiling sulfuric acid for a 3 h treatment duration led to the highest removal of the impurities with the least destructive effect. Moreover, it was observed that acid treatment results in decreasing of CNTs diameter.

Mortazavi, Seyedeh Z.; Novinrooz, Abdul J.; Reyhani, Ali; Mirershadi, Soghra

2010-12-01

205

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

2004-08-13

206

Measurement of fossil fuel carbon dioxide and other anthropogenic trace gases from MEGAPOLI intensive campaign in Paris during winter 2010.  

NASA Astrophysics Data System (ADS)

The Paris agglomeration is the third biggest megacity in Europe (12 million inhabitants) and according to national emission inventories, is responsible for 15 % of the French anthropogenic CO2 emissions mainly originating from road transport, and residential and industrial energy consumption. The objective of our feasibility study was to design an efficient monitoring strategy in order to quantify future trends in anthropogenic CO2 emission in Paris area. During the winter campaign of the European project MEGAPOLI and the French project CO2-MEGAPARIS, we performed measurements of CO2 and related trace gases from January to February 2010. The RAMCES (Atmospheric Network for Greenhouse Gases Monitoring) team at LSCE monitored CO2 and CO mixing ratio with high temporal resolution using instruments based on Cavity Ring Down Spectroscopy (CRDS) in the thirteenth arrondissement of Paris (south). We also sampled air in more than fifty flasks covering three full days at the same place. Flask were analysed in the RAMCES central laboratory with a Gas Chromatograph system for CO2, CO, CH4, N2O, SF6 and H2 mixing ratios and also by Mass Spectroscopy for CO2 isotopic ratios (?13C and ?18O). In order to quantify the fossil fuel CO2 (CO2ff) most flasks were analysed at INSTAAR for ?14C in CO2. In addition, 13CO2 isotopic ratio and total CO2 concentration were measured at high temporal resolution (< 1 min) over three days at Paris with the SIMCO instrument developed at LPMAA. In parallel with the Paris measurements, in-situ CO2, CO and other trace gases were monitored at Gif-sur-Yvette, a semi urban station 20km south west of Paris and also at the Trainou tower, 100 km south of Paris. Similar synoptic variations of CO2and CO mixing ratios were found in Paris and Gif with maximum mixing ratio up to 495 ppm CO2 and 1000 ppb CO downtown Paris. The mean diurnal variation during this winter period shows a peak to peak amplitude of 15 ppm CO2 and 150 ppb CO at Paris and 10 ppm CO2 and 40 CO ppb at Gif station. Using the MEGAPOLI database we will test different tracers (CO, VOCs, NOx) as possible candidate to quantify CO2ff (fossil fuel) based on calibration of these tracers against CO2ff estimates based on D14C. These results from the campaign will be compared to the emission inventories from EDGAR 4.2 (global inventories) and the national ones from CITEPA and AirParif.

Lopez, M.; Schmidt, M.; Delmotte, M.; Gros, V.; Mondelain, D.; Lehman, S. J.; Ramonet, M.; Vuillemin, C.; Xueref-Remy, I.

2012-04-01

207

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

208

Preparation and Characterization of Poly (1, 3-propylene glycol-hexanedioic acid)-functionalized Carbon Nanotubes  

Microsoft Academic Search

An in situ process was used to prepare poly (1, 3-propylene glycol-hexanedioic acid)-functionalized carbon nanotubes using carboxylate-functionalized multi-walled carbon nanotubes, 1, 3-propylene glycol and hexanedioic acid as reactants. The functionalized carbon nanotubes were characterized using transmission electronic microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The results indicated that the carboxylate-functionalized carbon nanotubes chemically reacted and were linked with the

Qing-Jie Meng; Xing-Xiang Zhang; Xue-Chen Wang

2007-01-01

209

Hydrogen storage and delivery: the carbon dioxide - formic acid couple.  

PubMed

Carbon dioxide and the carbonates, the available natural C1 sources, can be easily hydrogenated into formic acid and formates in water; the rate of this reduction strongly depends on the pH of the solution. This reaction is catalysed by ruthenium(II) pre-catalyst complexes with a large variety of water-soluble phosphine ligands; high conversions and turnover numbers have been realised. Although ruthenium(II) is predominant in these reactions, the iron(II) - tris[(2-diphenylphosphino)-ethyl]phosphine (PP3) complex is also active, showing a new perspective to use abundant and inexpensive iron-based compounds in the CO2 reduction. In the catalytic hydrogenation cycles the in situ formed metal hydride complexes play a key role, their structures with several other intermediates have been proven by multinuclear NMR spectroscopy. In the other hand safe and convenient hydrogen storage and supply is the fundamental question for the further development of the hydrogen economy; and carbon dioxide has been recognised to be a viable H2 vector. Formic acid--containing 4.4 weight % of H2, that is 53 g hydrogen per litre--is suitable for H2 storage; we have shown that in aqueous solutions it can be selectively decomposed into CO-free (CO < 10 ppm) CO2 and H2. The reaction takes place under mild experimental conditions and it is able to generate high pressure H2 (up to 600 bar). The cleavage of HCOOH is catalysed by several hydrophilic Ru(II) phosphine complexes (meta-trisulfonated triphenylphosphine, mTPPTS, being the most efficient one), either in homogeneous systems or as immobilised catalysts. We have also shown that the iron(II)--hydrido tris[(2-diphenylphosphino)ethyl]phosphine complex catalyses with an exceptionally high rate and efficiency (turnover frequency, TOF = 9425 h(-1)mol(-1); turnover number, TON = 92400) the formic acid cleavage, in environmentally friendly propylene carbonate solution, opening the way to use cheap, non-noble metal based catalysts for this reaction, too. PMID:22026175

Laurenczy, Gbor

2011-01-01

210

The effect of carbonic acid on well cements  

NASA Astrophysics Data System (ADS)

Sequestration in abandoned petroleum fields has the potential to reduce atmospheric emissions of CO2 if adopted on a large scale. When CO2 comes in contact with brine in the sequestration formation, it will form carbonic acid. The acid may damage cement that is used to construct and abandon wells in the sequestration formation, allowing the wells to leak. CO2 release from a sequestration formation through abandoned wells to the vadose zone and then from the vadose zone into a residence could cause exposure to high levels of CO2. This study presents the results of two types of experiments that were conducted in order to understand how CO2 will affect well cements. This dissertation also presents a hypothetical risk assessment that examines the risks that a sequestration site may pose. The experiments examine how well cements react when exposed to carbonated brines at 20 and 50C. Month-long flow-through experiments were conducted on samples made from Class H neat paste and Class H cement containing 6% bentonite under conditions that simulated sandstone (pH 2.4 and 3.7) and limestone (pH 5) sequestration formations. Year-long batch experiments were conducted on composite samples made from Class H well cement and either sandstone or limestone in order to determine how carbonated brine affects the cement-stone interface. The results of the flow-through experiments showed that calcium-containing phases in cement may be completely degraded and the formation of the calcium carbonate layer acts to slow, but not stop, degradation. The results of the batch experiments showed that carbonated brines can degrade cement and damage the integrity of the cement-stone interface. The damage to the cement at the cement-stone interface caused an order-of-magnitude increase in permeability in the sandstone-cement samples. The risk assessment identifies two potential screening levels. The assessment then uses a semianalytical wellfield model coupled with analytical models of diffusion through the vadose zone and foundation walls to establish CO 2 concentrations in residential basements. The results show CO 2 levels may not reach either screening level unless the value of the air-exchange rate in the houses is small.

Duguid, Andrew

211

The effect of co-impregnated acids on the performance of Zn-based broad spectrum respirator carbons.  

PubMed

Impregnated activated carbons (IACs) that are used in multi-gas respirator applications usually contain copper and/or zinc impregnants. Co-impregnating with properly selected acids can improve the distribution of the metallic impregnant on the carbon and improve the gas adsorption capacity of the IAC. In this work a comparative study of some common acids co-impregnated with a zinc nitrate (Zn(NO(3))(2)) precursor is performed. The IACs were heated in an inert atmosphere at temperatures which promoted the thermal decomposition of Zn(NO(3))(2) to zinc oxide (ZnO). The gas adsorption properties of the IACs were tested using ammonia (NH(3)), sulphur dioxide (SO(2)) and hydrogen cyanide (HCN) challenge gases. Powder X-ray diffraction (XRD) was used to identify the impregnant species present after heating and to study impregnant distribution. Gravimetric analysis was used to determine the impregnant loading, and help to identify the impregnant species after heating. The interactions between the co-impregnated acid and Zn(NO(3))(2) precursor during heating are discussed. The relationship between impregnant species and gas adsorption capacity is discussed. PMID:22951225

Smith, J W H; Romero, J V; Dahn, T R; Dunphy, K; Croll, L M; Dahn, J R

2012-08-07

212

Comparison of acid gas removal processes. Final report. Series No. I: D-1  

Microsoft Academic Search

In a coal gasification plant, the acid gases, carbon dioxide and hydrogen sulfide, must be removed from the raw gases in order to produce a purified high Btu product. The carbon dioxide is removed in order to eliminate dilution of the product gas. The hydrogen sulfide is removed to protect methanation catalyst and to meet pipeline gas specifications. Removal of

K. G. Christensen; W. J. Stupin

1978-01-01

213

Pyrolytic carbon membranes containing silica derived from poly(imide siloxane): the effect of siloxane chain length on gas transport behavior and a study on the separation of mixed gases  

Microsoft Academic Search

Poly(imide siloxane) (PIS) precursors have been synthesized in different compositions and appraised in their ability to form carbon membranes containing silica (CSiO2). During inert pyrolysis, the imide domains in the PIS were transformed into a carbon-rich phase conferring a molecular sieving capability for molecular pairs of small gases, such as H2\\/N2, He\\/N2, CO2\\/N2, and O2\\/N2. The siloxane domains in the

Ho Bum Park; Chul Ho Jung; Youn Kook Kim; Sang Yong Nam; Sun Yong Lee; Young Moo Lee

2004-01-01

214

Raman spectroscopic study of the phase transition of amorphous to crystalline beta-carbonic acid.  

PubMed

What's the matter? The laboratory Raman spectra for carbonic acid (H(2)CO(3)), both for the beta-polymorph and its amorphous state, are required to detect carbonic acid on the surface of the pole caps of Mars in 2009, when the Mars Microbeam Raman Spectrometer lands on the planet. The picture shows a martian crater with ice of unknown composition, possibly containing carbonic acid (image adapted from DLR, with permission from ESA, DLR, and FU Berlin--G. Neukum). PMID:19212997

Kohl, Ingrid; Winkel, Katrin; Bauer, Marion; Liedl, Klaus R; Loerting, Thomas; Mayer, Erwin

2009-01-01

215

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

NASA Astrophysics Data System (ADS)

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.

Prasek, Jan; Huska, Dalibor; Jasek, Ondrej; Zajickova, Lenka; Trnkova, Libuse; Adam, Vojtech; Kizek, Rene; Hubalek, Jaromir

2011-05-01

216

Highly efficient procedure for the synthesis of fructone fragrance using a novel carbon based acid.  

PubMed

The novel carbon based acid has been synthesized via one-step hydrothermal carbonization of furaldehyde and hydroxyethylsulfonic acid. A highly efficient procedure for the synthesis of fructone has been developed using the novel carbon based acid. The results showed that the catalyst possessed high activity for the reaction, giving a yield of over 95%. The advantages of high activity, stability, reusability and low cost for a simple synthesis procedure and wide applicability to various diols and beta-keto esters make this novel carbon based acid one of the best choices for the reaction. PMID:20714302

Hu, Baowei; Li, Chunqing; Zhao, Sheng-Xian; Rong, Lin-Mei; Lv, Shao-Qin; Liang, Xuezheng; Qi, Chenze

2010-08-05

217

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

218

Helium: its relationship to geologic systems and its occurrence with the natural gases, nitrogen, carbon dioxide, and argon  

Microsoft Academic Search

This Federal Bureau of Mines report presents information on the accumulation and distribution of helium in US natural gas reservoirs. The investigation concerns the relationship or association of helium with geographic location, geologic age, reservoir depth, nitrogen, carbon dioxide, and argon. Although helium is a minor constituent in natural gas, these data show that certain conditions make some reservoirs statistically

Tongish

1980-01-01

219

Carbon Dioxide Information Analysis Center and World Data Center-A for atmospheric trace gases: Fiscal year 1995 annual report  

SciTech Connect

Fiscal year 1995 was both a very productive year for the Carbon Dioxide Information Analysis Center and a year of significant change. This document presents information about the most notable accomplishments made during the year. Topics include: high-lights; statistics; future plans; publications, presentations, and awards; and change in organization and staff.

Burtis, M.D. [comp.; Cushman, R.M.; Boden, T.A.; Jones, S.B.; Nelson, T.; Stoss, F.W.

1996-01-01

220

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

221

A Simple Demonstration of Carbon Dioxide Fixation and Acid Production in CAM Plants  

ERIC Educational Resources Information Center

|Described is an experiment investigating carbon dioxide fixation in the dark and the diurnal rhythm of acid production in plants exhibiting Crassulacean Acid Metabolism. Included are suggestions for four further investigations. (SL)|

Walker, John R. L.; McWha, James A.

1976-01-01

222

Carbon paste electrode spiked with ferrocene carboxylic acid and its application to the electrocatalytic determination of ascorbic acid  

Microsoft Academic Search

A carbon paste electrode spiked with ferrocene carboxylic acid (FCAMCPE) was constructed by incorporation of ferrocene carboxylic acid in a graphite powderparaffin oil matrix. It has been shown by direct current cyclic voltammetry and double step chronoamperometry that this electrode can catalyze the oxidation of ascorbic acid in aqueous buffered solution. It has been found that under optimum conditions (pH

Jahan-Bakhsh Raoof; Reza Ojani; Abolfazl Kiani

2001-01-01

223

Water-soluble organic carbon, dicarboxylic acids, ketoacids, and ?-dicarbonyls in the tropical Indian aerosols  

Microsoft Academic Search

Tropical aerosol (PM10) samples (n = 49) collected from southeast coast of India were studied for water-soluble dicarboxylic acids (C2C12), ketocarboxylic acids (C2C9), 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

Chandra Mouli Pavuluri; Kimitaka Kawamura; T. Swaminathan

2010-01-01

224

The Family of HIGHSULF TM Processes. Improvement of Amine Desulfurization and Aftertreatment of Tail Gases  

Microsoft Academic Search

HIGHSULFTM processes increase the efficiency of amine desulfurization of gases: they increase emission of carbon dioxide above the absorber, significantly decrease the hydrocarbon content in the acid gas and increase the concentration of hydrogen sulfide, i.e., they increase the efficiency of extraction of sulfur in a Claus unit. HIGHSULFTM is easily applied to any units of the SCOT type for

T. K. Khanmamedov

2003-01-01

225

Abundances of Cloud-Related Gases in the Venus Atmosphere as Inferred from Observed Radio Opacity  

Microsoft Academic Search

Various radio-analytical techniques have detected microwave opacity in the middle atmosphere of Venus, well above the main carbon dioxide opacity of the lower atmosphere. Consideration of the amount, distribution, and effects of the constituents which produce the main cloud layer at about 50 km altitude, indicate that such cloud-related gases, especially sulfuric acid vapor, are the predominant source of the

Paul Gregory Steffes

1982-01-01

226

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.

227

A study of micropores in single-walled carbon nanotubes by the adsorption of gases and vapors  

Microsoft Academic Search

Adsorption of N2, benzene and methanol have been studied on as-prepared single-walled carbon nanotubes (SWNT) as well as SWNTs treated with HCl and HNO3. These nanotubes are good microporous materials with total surface areas well above 400 m2\\/g and internal surface areas of 300 m2\\/g or higher. Benzene molecules are shown to be adsorbed within the pores of the SWNTs.

M. Eswaramoorthy; Rahul Sen; C. N. R. Rao

1999-01-01

228

Usefulness of Transcutaneous Carbon Dioxide Pressure Monitoring to Measure Blood Gases in Adults Hospitalized for Respiratory Disease  

Microsoft Academic Search

OBJECTIVE: To evaluate the usefulness of transcutaneous carbon dioxide pressure (TcPCO2) monitoring in patients hospitalized for respiratory disease. PATIENTS AND METHODS: We used a SenTec TcPCO2 monitor that also determines transcutaneous oxygen saturation (SpO2) by means of a sensor placed behind the ear lobe at a temperature of 42 degrees C. We compared arterial blood gas measurements--PaCO2 and arterial oxygen

A. Herrejn; I. Inchaurraga; J. Palop; S. Ponce; R. Peris; M. Terrdez; R. Blanquer

2006-01-01

229

Carbon and hydrogen isotopic compositions and their evolutions of gases generated by herbaceous swamp peat at different thermal maturity stages  

Microsoft Academic Search

Coalbed methane (CBM) accumulation models include continuous gas accumulation and staged gas accumulation. However, studied\\u000a on the geochemical characteristics and indices to evaluate staged accumulation CBM are lacking. This study for the first time\\u000a obtained the carbon and hydrogen isotopic compositions of methane and ethane generated at different evolution stages using\\u000a thermal simulation of samples prepared by treating an herbaceous

Yi Duan; XiaoLi Zhang; Tao Sun; BaoXiang Wu; JinXian He; Li Xu

2011-01-01

230

Studies of the terrestrial O{sub 2} and carbon cycles in sand dune gases and in biosphere 2  

SciTech Connect

Molecular oxygen in the atmosphere is coupled tightly to the terrestrial carbon cycle by the processes of photosynthesis, respiration, and burning. This dissertation examines different aspects of this coupling in four chapters. Chapter 1 explores the feasibility of using air from sand dunes to reconstruct atmospheric O{sub 2} composition centuries ago. Such a record would reveal changes in the mass of the terrestrial biosphere, after correction for known fossil fuel combustion, and constrain the fate of anthropogenic CO{sub 2}.

Severinghaus, J.P.

1995-12-31

231

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 ...

232

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...

233

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

SciTech Connect

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 gravimetric methods at CMDL and has been propagated to a set of working standards. In this paper we compare CO mixing ratios assigned to the working standards by three approaches: (1) calibration against the original gravimetric standards, (2) calibration using only working standards as the reference gas, and (3) calibration against three new gravimetric standards prepared to CMDL. The agreement between these values was typically better than 1%. The calibration histories of CMDL working standards are reviewed with respect to expected rates of CO change in the atmosphere. Using a Monte Carlo approach to simulate the effect of drifting standards on calculated mixing ratios, we conclude that the error solely associated with the maintenance of standards will limit the ability to detect small CO changes in the atmosphere. We also report results of intercalibration experiments conducted between CMDL and the Diode Laser Sensor Group (DACOM) at the NASA Langley Research Center (Hampton, Virginia), and CMDL and the Fraunhofer-Institut (Garmisch-Partenkirchen, Germany). Each laboratory calibrated several working standards for CO using their reference gases, and these results were compared to calibrations conducted by CMDL. The intercomparison of eight standards (CO concentrations between approximately 100 and approximately 165 ppb) by CMDL and NASA agreed to better than +/- 2%. (Abstract Truncated)

Novelli, P.C.; Collins, J.E. Jr.; Myers, R.C.; Sachse, G.W.; Scheel, H.E. [Univ. of Colordo, Boulder, CO (United States)]|[Science and Technology Corporation, Hampton, VA (United States)]|[NOAA, Boulder, CO (United States)]|[NASA, Langley Research Center, Hampton, VA (United States)]|[Fraunhofer-Inst. fuer Atmospharishce Umweltforschung (Germany)

1994-06-01

234

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, LCMS and NMR spectroscopy. Regardless of

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

2010-01-01

235

Toxic gases.  

PubMed Central

An overview of the widespread use of gases and some volatile solvents in modern society is given. The usual circumstances in which undue exposure may occur are described. The most prominent symptoms and general principles of diagnosis and treatment are given and are followed by more specific information on the commoner, more toxic materials. While acute poisonings constitute the greater part of the paper, some indication of chronic disorders arising from repeated or prolonged exposure is also given.

Matthews, G.

1989-01-01

236

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 (410-15 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

237

BIOMASS BURNING AND THE PRODUCTION OF GREENHOUSE GASES  

Microsoft Academic Search

Biomass burning is a source of greenhouse gases, carbon dioxide, methane, and nitrous oxide. In addition, biomass burning is a source of chemically active gases, including carbon monoxide, nonmethane hydrocarbons, and nitric oxide. These gases, along with methane, lead to the chemical production of tropospheric ozone (another greenhouse gas) as well as control the concentration of the hydroxyl radical, which

Joel S. Levine

238

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

239

Poly( o-aminophenol)-modified bienzyme carbon paste electrode for the detection of uric acid  

Microsoft Academic Search

A reagentless uric acid selective biosensor constructed by immobilising uricase and horseradish peroxidase (HRP) in carbon paste without the addition of an electron transfer mediator is described. The response of the electrode is based on the enzymatic reduction of hydrogen peroxide in the presence of uric acid. Uricase and HRP were dispersed in the carbon paste and the optimum paste

E. Miland; A. J. Miranda Ordieres; P. Tun Blanco; M. R. Smyth; C. . Fgin

1996-01-01

240

Preparation of carbon fibers from softwood lignin by atmospheric acetic acid pulping  

Microsoft Academic Search

Infusible softwood acetic acid lignin (SAL) was converted to a fusible one as a raw material for carbon fibers by removing the infusible high molecular mass fraction. The resulting low molecular mass fraction (SAL-L) was spun by fusion spinning after thermal treatment to remove volatile materials. Carbon fibers (CFs) were prepared from these fibers by direct carbonization without thermostabilization, leading

S. Kubo; Y. Uraki; Y. Sano

1998-01-01

241

Study of carbon nanotube modified biosensors for monitoring uric acid and total cholesterol in blood  

Microsoft Academic Search

The carbon nanotube modified biosensors for respectively monitoring uric acid (UA) and total cholesterol in blood were studied. The transducers were based on two screen-printed carbon electrodes, a carbon working electrode and a reference electrode. For UA sensors, uricase was immobilized on the surface of electrodes together with potassium ferrocyanide as electron transfer mediator. For cholesterol sensors, the corresponding enzyme

Hui Xu; Guang Li; Min Fu; You Wang; Jun Liu

2005-01-01

242

Removal of Cr(VI) from aqueous solution using activated carbon modified with nitric acid  

Microsoft Academic Search

The adsorption processes of Cr(VI) from aqueous solution onto a granular activated carbon (GAC) and a modified activated carbon (MAC) with nitric acid have been investigated. The surface characteristics of these two activated carbons were measured. The results showed that the MAC has a lower surface area, lower pHIEP and more oxygen functional groups compared with the GAC. Adsorption parameters

Guolin Huang; Jeffrey X. Shi; Tim A. G. Langrish

2009-01-01

243

Arundo donax cane as a precursor for activated carbons preparation by phosphoric acid activation  

Microsoft Academic Search

Canes from Arundo donax, a herbaceous rapid-growing plant, were used as precursor for activated carbon preparation by phosphoric acid activation under a self-generated atmosphere. The influence of the carbonization temperature in the range 400550 C and of the weight ratio phosphoric acid to precursor (R=1.52.5) on the developed porous structure of the resulting carbons was studied for 1 h of

T Vernersson; P. R Bonelli; E. G Cerrella; A. L Cukierman

2002-01-01

244

Acrylic acid-diphenylamine sulphonic acid copolymer threshold inhibitor for sulphate and carbonate scales in cooling water systems  

Microsoft Academic Search

Formation of mineral scales of carbonate and sulphate poses significant problems in cooling water systems. For the control of calcium carbonate and calcium sulphate scales, copolymer of acrylic acid-diphenyl amine sulphonic acid (AA-DPSA) was tried as the anticalant in the respective brines. The copolymer of AA-DPSA was synthesized by following a free radical polymerization procedure. AA-DPSA was characterized by Fourier

P. Shakkthivel; T. Vasudevan

2006-01-01

245

Adsorption equilibrium and transport kinetics for a range of probe gases in Takeda 3A carbon molecular sieve.  

PubMed

Measurements of adsorption equilibria and transport kinetics for argon, oxygen and nitrogen at 20, 50, and 80 degrees C on commercially derived Takeda carbon molecular sieve (CMS) employed for air separation have been undertaken in an effort to elucidate fundamental mechanisms of transport. Results indicate that micropore diffusion which is modeled by a Fickian diffusion process, governs the transport of oxygen molecules and the pore mouth barrier controls argon and nitrogen transport which is characterized by a linear driving force (LDF) model. For the three temperatures studied, the pressure dependence of the diffusivity and the LDF rate constant appear to be well characterized by a formulation based on the chemical potential as the driving force for transport. Isosteric heat of adsorption at zero loading and activation energy measurements are compared with predictions made from a previously proposed molecular model for characterizing CMS. PMID:15780279

Rutherford, S W; Coons, J E

2005-04-15

246

Sequestering CO(2) by mineral carbonation: stability against acid rain exposure.  

PubMed

Mineral carbonation is a potentially attractive alternative to storage of compressed CO(2) in underground repositories, known as geosequestration. Processes for the conversion of basic ores, such as magnesium silicates, to carbonates have been proposed by various researchers, with storage of the carbonate as backfill in the original mine representing a solid carbon sink. The stability of such carbon sinks against acid rain and other sources of strong acids is examined here. It is acknowledged that in the presence of strong acid, carbonates will dissolve and release carbon dioxide. A sensitivity analysis covering annual average rainfall and pH that may be encountered in industrialized areas of the United States, China, Europe, and Australia was conducted to determine maximum CO(2) rerelease rates from mineral carbonation carbon sinks. This analysis is based on a worst-case premise that is equivalent to assuming infinitely rapid kinetics of dissolution of the carbonate. The analysis shows that under any likely conditions of pH and rainfall, leakage rates of stored CO(2) are negligible. This is illustrated in a hypothetical case study under Australian conditions. It is thus proposed that sequestration by mineral carbonation can be considered to be permanent on practical human time scales. Other possible sources of acid have also been considered. PMID:20199068

Allen, Daniel J; Brent, Geoff F

2010-04-01

247

Preparation of activated carbon from bituminous coal with phosphoric acid activation  

Microsoft Academic Search

Activated carbons were prepared from an Australian bituminous coal in this study. The preparation process consisted of phosphoric acid impregnation followed by carbonization in nitrogen at 400600C for 13hours. The results reveal that the surface area and pore volume of the resulting carbons increase with the chemical ratio, H3PO4\\/coal. Within the ranges of carbonization temperature and time, the chemically activated

Hsisheng Teng; Tien-Sheng Yeh; Li-Yeh Hsu

1998-01-01

248

Sorption of uranium from nitric acid solution using TBP-impregnated activated carbons  

SciTech Connect

The concept of extraction chromatography has been used to study the sorption of uranium from nitric acid solutions using tri-n-butyl phosphate (TBP) impregnated activated carbons. Batch equilibrium data and kinetic and breakthrough column behavior of uranium are reported. Wood based activated carbon has shown better capacity and breakthrough characteristics than shell based activated carbon. Sorption rate on impregnated carbons was relatively slow indicating that diffusion is the rate controlling step within the pore structure of the activated carbon. Uranium distribution on impregnated activated carbons is compared with equivalent bulk liquid extraction and a mechanism of uranium sorption is discussed.

Abbasi, W.A. [Pakistan Atomic Energy Commission, Islamabad (Pakistan). Pakistan Inst. of Nuclear Science and Technology; Streat, M. [Loughborough Univ. (United Kingdom). Dept. of Chemical Engineering

1998-08-01

249

Atmospheric carbon dioxide retrieved from the Greenhouse gases Observing SATellite (GOSAT): Comparison with ground-based TCCON observations and GEOS-Chem model calculations  

NASA Astrophysics Data System (ADS)

We retrieved column-averaged dry air mole fractions of atmospheric carbon dioxide (XCO2) from backscattered short-wave infrared (SWIR) sunlight measured by the Japanese Greenhouse gases Observing SATellite (GOSAT). Over two years of XCO2 retrieved from GOSAT is compared with XCO2 inferred from collocated SWIR measurements by seven ground-based Total Carbon Column Observing Network (TCCON) stations. The average difference between GOSAT and TCCON XCO2 for individual TCCON sites ranges from -0.87 ppm to 0.77 ppm with a mean value of 0.1 ppm and standard deviation of 0.56 ppm. We find an average bias between all GOSAT and TCCON XCO2 retrievals of -0.20 ppm with a standard deviation of 2.26 ppm and a correlation coefficient of 0.75. One year of XCO2 was retrieved from GOSAT globally, which was compared to global 3-D GEOS-Chem chemistry transport model calculations. We find that the latitudinal gradient, seasonal cycles, and spatial variability of GOSAT and GEOS-Chem agree well in general with a correlation coefficient of 0.61. Regional differences between GEOS-Chem model calculations and GOSAT observations are typically less than 1 ppm except for the Sahara and central Asia where a mean difference between 2 to 3 ppm is observed, indicating regional biases in the GOSAT XCO2 retrievals unobserved by the current TCCON network. Using a bias correction scheme based on linear regression these regional biases are significantly reduced, approaching the required accuracy for surface flux inversions.

Cogan, A. J.; Boesch, H.; Parker, R. J.; Feng, L.; Palmer, P. I.; Blavier, J.-F. L.; Deutscher, N. M.; Macatangay, R.; Notholt, J.; Roehl, C.; Warneke, T.; Wunch, D.

2012-11-01

250

Shared retronasal identifications of vapor-phase 18-carbon fatty acids.  

PubMed

The long-chain 18-carbon fatty acids linoleic, oleic, and stearic acids, retronasally in vapor phase, are discriminated from blanks and each other. However, ability to linguistically identify them was unknown. To explore this, a Focus Group and then Check-All-That-Apply measures gave 9 identifiers for the 3 fatty acids plus phenylethyl alcohol (PEA) and geraniol. Next, participants selected 1 of the 9 identifiers from a computer-based display. It was found that the modal identification for linoleic acid was 23% "Rubbery" (next 18% "Oily" and "New Plastic"), oleic acid was 21% Oily (next 19% Rubbery), and stearic acid was 43% Rubbery (next 22% New Plastic), but linoleic acid received ~40% food-related identifiers. Geraniol was 96% "Lemon," and PEA was 67% "Flowers." Identifications for fatty acids differed significantly (P ? 0.05) from those for geraniol for most participants (86%) and from those for PEA for 59% of participants. Stearic acid identifications differed significantly from those for linoleic and oleic acids for 32% of participants. However, identification for linoleic acid differed significantly from those for oleic acid for only 14% of participants. Overall, retronasal vapor-phase stearic acid was identified differently from other 18-carbon fatty acids by a substantial minority of participants, but linoleic and oleic acids were not, suggesting that these 2 vapor-phase 18-carbon fatty acids can be identified retronasally as a group but not separately. PMID:23424022

Chukir, Tariq; Darlington, Richard B; Halpern, Bruce P

2013-02-19

251

Surface characterization of acid-oxidized multi-walled carbon nanotubes  

Microsoft Academic Search

Multi-walled carbon nanotubes (MWNTs) oxidized with sulfuric acid, nitric acid, and the mixture of sulfuric and nitric acids were characterized by thermogravimetric analysis (TGA), Raman spectroscopy, elemental analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. The TGA data showed that the MWNTs were more resistant to oxidation than C60 or activated carbon fibers. Catalyst particles could be removed by the oxidants

Yu-Chun Chiang; Chien-Cheng Lee; Chen-Yueh Lee

2009-01-01

252

Anodic oxidation of 3,4-dihydroxyphenylacetic acid on carbon electrodes in acetic acid solutions.  

PubMed

The electrochemical oxidation of 3,4-dihydroxyphenylacetic acid (DOPAC) on a carbon fiber microelectrode (CF) and a glassy carbon macroelectrode (GC) in glacial acetic acid solutions was investigated using voltammetric techniques. Voltammograms recorded at these electrodes show well-defined single waves or peaks. The proposed mechanism of the anodic oxidation of DOPAC consists of two successive one-electron one-proton steps. The loss of the first electron proceeds irreversibly and determines the overall rate of the electrode process. This stage is accompanied by the generation of an unstable phenoxyl radical in position 4 of the aromatic ring. The second stage of the electrode reaction produces substituted orto-quinone as the final product of the electrode process of DOPAC. DOPAC exhibits more antioxidative power than synthetic BHT and can be useful in food protection against reactive oxygen species. The results presented can help to explain biochemical and antioxidative properties of DOPAC in a living cell and can be useful in determination of this compound in real samples. PMID:20004625

Michalkiewicz, Slawomir; Skorupa, Agata

2009-12-03

253

Carbon-doped high-mobility hole gases on (0 0 1) and (1 1 0) GaAs  

NASA Astrophysics Data System (ADS)

Since Stormer and Tsang have introduced the first two-dimensional hole gas (2DHG) in the GaAs/AlGaAs heterosystem, the choice of suitable dopants was limited to beryllium and silicon over the last 20 years. Both acceptor atoms have significant disadvantages, i.e. either high-diffusion rates or a limitation to specific growth directions. Utilizing a carbon filament-doping source, we prepared high-quality 2DHGs in the (0 0 1) and the nonpolar (1 1 0) crystal plane with carrier mobilies beyond 106 cm2/Vs in quantum well and single interface structures. Low-temperature magnetoresistance measurements recover a large number of fractional QHE states and show a pronounced beating pattern from which the Rashba induced spin-splitting has been determined. In addition, 2DHGs have been grown on cleaved edges of (1 1 0) and (0 0 1) wafers with transport features in qualitative agreement to our findings on (1 1 0) substrates.

Gerl, C.; Schmult, S.; Wurstbauer, U.; Tranitz, H.-P.; Mitzkus, C.; Wegscheider, W.

2006-05-01

254

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

255

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

2012-06-21

256

Microbial degradation of beta-chlorinated four-carbon aliphatic acids.  

PubMed Central

Alcaligenes sp. strain CC1 is able to grow on several alpha-chlorinated aliphatic acids (2-chlorobutyrate, 2-chloropropionate, and chloroacetate), as well as on the beta-chlorinated four-carbon aliphatic acids trans-3-chlorocrotonate, cis-3-chlorocrotonate, and 3-chlorobutyrate as sole carbon and energy sources. Dehalogenation of alpha-chlorinated acids could be measured by using resting cells grown on all the different carbon sources, whereas dehalogenation of beta-chlorinated four-carbon acids could be detected only by using resting cells grown on four-carbon compounds. A constitutive 2-haloacid dehalogenase, which did not show any activity with beta-chlorinated four-carbon acids, was detected in cell extracts. Cell extracts of crotonate-grown cells additionally contained a beta-haloacid dechlorination activity, which acted on trans-3-chlorocrotonate, cis-3-chlorocrotonate, and 3-chlorobutyrate and was strictly dependent on coenzyme A, ATP, and Mg2+. Dechlorination of beta-chlorinated four-carbon acids takes place after activation of the acids to their coenzyme A derivatives and seems to be independent of the constitutive 2-haloacid dehalogenase.

Kohler-Staub, D; Kohler, H P

1989-01-01

257

Activated carbon fibers from Nomex by chemical activation with phosphoric acid  

Microsoft Academic Search

The preparation of activated carbon fibers (ACFs) by phosphoric acid activation of Nomex [poly(m-phenylene isophthalamide)] polyaramid fibers was studied. Nomex pyrolysis in the presence of phosphoric acid was followed by thermogravimetry and infrared spectroscopy in order to establish the nature of transformations involved. Then, ACFs were obtained by impregnating Nomex with different amounts of phosphoric acid, followed by pyrolysis and

Fabin Surez-Garc??a; Amelia Mart??nez-Alonso; Juan M. D Tascn

2004-01-01

258

Measurement of functionalised carbon nanotube carboxylic acid groups using a simple chemical process  

Microsoft Academic Search

Chemically functionalised single-walled carbon nanotubes were formed using sonication in a mixture of concentrated sulphuric and nitric acids for varying lengths of time which resulted in carboxylic acid group functionalisation, predominantly at the ends. The carboxylic acid groups were used to form an ionic bond with dodecylamine. The weight of this complex was used to monitor the number of carboxylic

Matthew W. Marshall; Simina Popa-Nita; Joseph G. Shapter

2006-01-01

259

Hydrothermal carbonization of microalgae II. Fatty acid, char, and algal nutrient products  

Microsoft Academic Search

A process for isolation of three products (fatty acids, chars and nutrient-rich aqueous phases) from the hydrothermal carbonization of microalgae is described. Fatty acid products derived from hydrolysis of fatty acid ester groups in the microalgae were obtained in high yield and were found to be principally adsorbed onto the char also created in the process. With the highest lipid-containing

Steven M. Heilmann; Lindsey R. Jader; Laurie A. Harned; Michael J. Sadowsky; Frederick J. Schendel; Paul A. Lefebvre; Marc G. von Keitz; Kenneth J. Valentas

2011-01-01

260

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

261

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

262

Acid rain, zooplankton fecal pellets and the global carbon budget  

Microsoft Academic Search

Some five to seven billion metric tons (BMT) of carbon dioxide are produced each year from fossil fuel burning and forest cutting. Of this, one to several BMT are unaccounted for in the increases in carbon dioxide observed in the atmosphere and dissolved in the sea. Any additional sink for this ''missing'' carbon must be large-scale, increasing and not balanced

C. A. S. Hall; G. Roe; J. H. Ryther; G. M. Woodwell

1977-01-01

263

Kinetics of hydrogen peroxide decomposition in aqueous sulfuric acid over palladium\\/carbon: effcet of acid concentration  

Microsoft Academic Search

Decomposition of H2O2 over Pd (5%)\\/carbon in an aqueous sulfuric acid solution at different acid concentrations (0-10 mol\\/L) and temperatures (281-313\\u000a K) in a magnetically stirred glass reactor has been investigated. The catalytic activity, activation energy and frequency\\u000a factor for the decomposition decrease with increasing acid concentration; the decrease in the activation energy is, however,\\u000a very small.

Vasant R. Choudhary; Abaji G. Gaikwad

2003-01-01

264

Multilayer films of carbon nanotubes and redox polymer on screen-printed carbon electrodes for electrocatalysis of ascorbic acid  

Microsoft Academic Search

Multilayer films containing multiwall carbon nanotubes and redox polymer were successfully fabricated on a screen-printed carbon electrode using layer-by-layer (LBL) assembled method. UVvis spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy and electrochemical method were used to characterize the assembled multilayer films. The multilayer films modified electrodes exhibited good electrocatalytic activity towards the oxidation of ascorbic acid (AA). Compared with

Yufang Sha; Lei Qian; Ying Ma; Haixin Bai; Xiurong Yang

2006-01-01

265

How Greenhouse Gases Absorb Heat  

NSDL National Science Digital Library

Learners observe two model atmospheres -- one with normal atmospheric composition and another with an elevated concentration of carbon dioxide. These two model atmospheres are exposed to light energy from a sunny window or from a lamp. This activity will help learners understand that greenhouse gases in the atmosphere absorb and hold heat, relating to global warming and climate change.

History, American M.

2008-01-01

266

Voluntary Reporting of Greenhouse Gases Archive  

EIA Publications

The Voluntary Reporting of Greenhouse Gases Program established a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., can report to the EIA, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

Joe Ayoub

267

Method of processing of waste gases  

Microsoft Academic Search

A method is described of processing of waste gases containing hydrogen fluoride and silicon tetrafluoride or hydrogen fluoride, silicon tetrafluoride and sulfur dioxide by absorption of hydrogen fluoride and silicon tetrafluoride or hydrogen fluoride, silicon tetrafluoride and sulfur dioxide from waste gases by water solutions containing ammonium compounds such as ammonium carbonate, ammonium bicarbonate and ammonium fluoride. In addition to

V. S. Kalach; L. I. Burlakova

1976-01-01

268

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-Vign, Patricia; Sevilla, Marta; Fuertes, Antonio B.

2012-11-01

269

Acid yellow 9 as a dispersing agent for carbon nanotubes: Preparation of redox polymercarbon nanotube composite film and its sensing application towards ascorbic acid and dopamine  

Microsoft Academic Search

In this study, we show that acid yellow 9 (4-amino-1-1?-azobenzene-3,4?-disulfonicacid, AY) is a good stabilizing agent for multi-walled carbon nanotubes (MWCNTs). MWCNTs dispersed in AY solution was remained stable about three months and even remained stable after centrifugation at 10,000rpm for 30min. Using MWCNTs\\/AY dispersion, thin-films were prepared on indium tin oxide coated glass electrode and glassy carbon electrodes. Further,

S. Ashok Kumar; Sea-Fue Wang; Thomas C.-K. Yang; Chun-Ting Yeh

2010-01-01

270

Chemical and isotopic characterization of the gases of Mount Etna (Italy)  

Microsoft Academic Search

In the period 19901995, 43 samples of dissolved gases in groundwaters (wells, springs and drainage galleries) and 64 samples of free gases (fumaroles, bubbling and soil gases) from the Mount Etna area were collected and analysed. Isotopic analyses were also carried out of both the carbon of the CO2 in free gases and dissolved inorganic carbon (DIC) in the waters.

W. D'Alessandro; S. De Gregorio; G. Dongarr; S. Gurrieri; F. Parello; B. Parisi

1997-01-01

271

Preparation and characterization of biomass carbon-based solid acid catalyst for the esterification of oleic acid with methanol.  

PubMed

A solid acid catalyst, prepared by sulfonating carbonized corn straw, was proved to be an efficient and environmental benign catalyst for the esterification of oleic acid and methanol. Various synthetic parameters, such as carbonization temperature and time were systematically examined. It was found that the catalyst exhibited the highest acid density of 2.64 mmol/g by NaOH titration. A quantitative yield (98%) of ester was achieved, using the most active sulfonated catalyst at 333 K with a 7 wt.% catalyst/oleic acid ratio for 4h, at a 7:1 M ratio of methanol/oleic acid, while the commercial available Amberlyst-15 only gave 85% yield under the same reaction condition. PMID:23453798

Liu, Tiantian; Li, Zhilong; Li, Wei; Shi, Congjiao; Wang, Yun

2013-02-09

272

Comparison of Emissions and Ambient Concentrations of Carbon Monoxide, Nitrogen Oxides and Nonmethane Organic Gases in California's South Coast Air Basin  

NASA Astrophysics Data System (ADS)

In the present study, a "top-down" validation of the reactive organic gas and carbon monoxide emission inventories for California's South Coast Air Basin was performed by comparing speciation profiles for nonmethane organic gases (NMOG) and ratios of CO/NO_ {rm x} and NMOG/NO_ {rm x} derived from early-morning (0700 to 0800) ambient measurements taken during the 1987 Southern California Air Quality Study with the corresponding ratios and speciation profiles derived from day-specific, hourly, gridded emission inventories. Twenty separate comparisons were examined for each pollutant ratio, each comparison representing a different combination of season, emission category, and spatial and temporal averaging of emissions. For the most appropriate comparisons, the ambient CO/NO_{rm x} and NMOG/NO_{rm x} ratios are about 1.5 and 2 to 2.5 times higher, respectively, than the corresponding inventory ratios. On the assumption that inventories of NO_{rm x } emissions are reasonably correct, these results indicate that on-road motor vehicle CO and NMOG emissions are significantly underestimated. Comparisons of long -term trends in ambient 0600-0900 CO/NO_ {rm x} and NMHC/NO_ {rm x} ratios with corresponding trends in emission inventory ratios show similar differences, indicating that a discrepancy between ambient and emission inventory pollutant ratios has existed for some time. It is postulated that actual ROG emissions in the SoCAB were 700 to 1000 tons/day higher than the ARB's emission inventory estimates for 1987. The underestimation of emissions has important implications for the validation and application of air quality simulation models, establishing baseline inventories to monitor the five percent annual emission reductions mandated by the California Clean Air Act, and quantifying the effectiveness of current and future emission control measures.

Fujita, Eric Masaru

273

Small-Scale Preparation of Glyoxylic Acid labelled with Carbon14  

Microsoft Academic Search

DURING the course of a study of glyoxylic acid metabolism in wheat it became desirable to obtain glyoxylate labelled with carbon-14, a compound which does not appear to be available commercially. Oxalic acid, which is available commercially as oxalic acid-14C, has been used in the synthesis of glyoxylic acid1-4. Weinhouse and Friedmann5 synthesized glyoxylate-14C from oxalate-14C by reduction with mercuric

R. M. Krupka; G. H. N. Towers

1958-01-01

274

The effect of lactic acid on anaerobic carbon or nitrogen limited chemostat cultures of Saccharomyces cerevisiae  

Microsoft Academic Search

Weak organic acids are well-known metabolic effectors in yeast and other micro-organisms. High concentrations of lactic acid due to infection of lactic acid bacteria often occurs in combination with growth under nutrient-limiting conditions in industrial yeast fermentations. The effects of lactic acid on growth and product formation of Saccharomyces cerevisiae were studied, with cells growing under carbon- or nitrogen-limiting conditions

Elisabeth Thomsson; Christer Larsson

2006-01-01

275

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

276

Molten Carbonate and Phosphoric Acid Stationary Fuel Cells: Overview and Gap Analysis  

SciTech Connect

This report describes the technical and cost gap analysis performed to identify pathways for reducing the costs of molten carbonate fuel cell (MCFC) and phosphoric acid fuel cell (PAFC) stationary fuel cell power plants.

Remick, R.; Wheeler, D.

2010-09-01

277

Stability of carbon nanowalls against chemical attack with acid solutions  

NASA Astrophysics Data System (ADS)

In this paper we report on the stability of CNW layers, synthesized by a radiofrequency plasma jet, against the chemical attack with different acid solutions (sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid). We present the changes of the morphology and structure of the CNW caused by the post-growth chemical treatments. We demonstrate that self-sustaining and transferable CNW layers can be obtained, by chemically dissolving the substrates, while the initial characteristics of the material are well preserved.

Vizireanu, Sorin; Dinescu, Gheorghe; Nistor, Leona Cristina; Baibarac, Mihaela; Ruxanda, Grigore; Stancu, Mihaela; Ciuparu, Dragos

2013-01-01

278

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

279

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

280

Electrooxidation of oxalic acid at a carbon-paste electrode with deposited palladium nanoparticles  

Microsoft Academic Search

Palladium nanoparticles deposited on the surface of a carbon-paste electrode exhibit electrocatalytic activity in the oxidation\\u000a of oxalic acid. The surface topography of modified carbon-paste electrodes (CPEs) and the shapes of the metal crystallite\\u000a particles were studied with atomic-force microscopy. These data were correlated with the voltammetric parameters of the electrooxidation\\u000a of palladium and oxalic acid. As the dispersity of

L. G. Shaidarova; I. A. Chelnokova; A. V. Gedmina; G. K. Budnikov; S. A. Ziganshina; A. A. Mozhanova; A. A. Bukharaev

2006-01-01

281

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

zgl Gerel; H. Ferdi Gerel

2009-01-01

282

Determination of oxalic acid in spinach with carbon nanotubes-modified electrode  

Microsoft Academic Search

This work investigated the electrocatalytic oxidation of oxalic acid on multiwall carbon nanotubes (MWNTs) modified glassy carbon (GC) electrode. The result indicated that the oxidation of oxalic acid was greatly improved at the MWNTs-modified GC (MWNTs\\/GC) electrode as compared with the bare GC electrode. The effects of the MWNTs suspension amount, pH and scan rate on the electrooxidation response of

Yanqiong Zheng; Changzhu Yang; Wenhong Pu; Jingdong Zhang

2009-01-01

283

Reactions of carbon monoxide with unsaturated fatty acids and derivatives: A review  

Microsoft Academic Search

The important reactions of carbon monoxide with unsaturated fatty derivatives that are reviewed in this paper include hydroformylation\\u000a (the oxo reaction), Koch carboxylation and Reppe carbonylation. With oleic acid as a substrate, the products are C19 bifunctional compounds e.g., formyl- or carboxy-stearic acid. Double bond isomerization before carbon monoxide addition is\\u000a characteristic of these catalytic reactions; additionally, rearrangement to introduce

E. H. Pryde; E. N. Frankel; J. C. Cowan

1972-01-01

284

Catalytic synthesis of benzoic esters with carbon-based solid acid from coal tar  

Microsoft Academic Search

A new carbon-based solid acid catalyst (C- SO3H) was prepared by simultaneous cross- linking coal tar with benzaldehyde,hoist temperature -curing ,sulphonation in sulfuric acid and was characterized by FT-IR,TG-DTG,XRD and neutralization potentiometric titration, and SEM techniques. The results indicated that there is the high density of SO3H groups in forming amorphous coke consisting of polycyclic aromatic carbon sheets, and the

Haie Hao; Baojun Ma; Jinxin Ma; Sun Yuan; Wanyi Liu

2011-01-01

285

Development of porosity in combined phosphoric acid-carbon dioxide activation  

Microsoft Academic Search

Five activated carbons with different porosity, prepared by chemical activation of peach stones with phosphoric acid, have been further activated in a carbon dioxide gas flow at 825 C for different periods of time to cover a wide range of burn-off. The porosity of all activated carbons was determined by adsorption of N2 (77 K), CO2 (273 K) and n-C4H10

M. Molina-Sabio; F. Rodrguez-Reinoso; F. Caturla; M. J. Sells

1996-01-01

286

Synthesis of biodiesel from cottonseed oil and methanol 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 and used to catalyze the transesterification of methanol with cottonseed oil. This catalyst was characterized by scanning electron microscopy\\/energy dispersive spectroscopy, BET surface area and pore size measurement, thermogravimetry analysis and Fourier transform infrared spectroscopy. The sulfonated multi-walled carbon nanotubes (s-MWCNTs) was also prepared and

Qing Shu; Qiang Zhang; Guanghui Xu; Zeeshan Nawaz; Dezheng Wang; Jinfu Wang

2009-01-01

287

Characterization and antimicrobial properties of fluorine-rich carbon films deposited on poly(lactic acid)  

Microsoft Academic Search

This study describes the effect of fluorine contents on the properties of carbon films deposited on poly(lactic acid) (PLA) substrate using plasma enhanced chemical vapor deposition (PECVD) technique. A mixture of acetylene (C2H2) and carbon tetrafluoride (CF4) gas was utilized for film deposition. The thickness of the deposited carbon film was in the range of 150350nm. The film's deposition rate

D. Boonyawan; S. Sarapirom; S. Tunma; C. Chaiwong; P. Rachtanapun; R. Auras

2011-01-01

288

Greenhouse gases from animal husbandry: mitigation options  

Microsoft Academic Search

Abatement strategies for direct emissions of greenhouse gases from animal husbandry are discussed. The reduction options are\\u000a divided into preventive and `end of pipe' options. Preventive measures reduce either the carbon and nitrogen input into the\\u000a system of animal husbandry or their output from the system, respectively. `End of pipe' measures reduce the formation of greenhouse\\u000a gases from carbon and

Joachim Clemens; Heinz-Jrgen Ahlgrimm

2001-01-01

289

Electrocatalytic oxidation of hydrazine at a chlorogenic acid (CGA) modified glassy carbon electrode  

Microsoft Academic Search

The electrocatalytic oxidation of hydrazine has been studied on a glassy carbon electrode modified by electrodeposition of chlorogenic acid (CGA), using cyclic voltammetry, chronoamperometry and rotating disk voltammetry as diagnostic techniques. At this modified electrode, the oxidation of hydrazine to nitrogen occurs at a potential where oxidation is not observed at the bare glassy carbon electrode. It has been found

S. M. Golabi; H. R. Zare

1999-01-01

290

Activated carbon from peach stones using phosphoric acid activation at medium temperatures.  

PubMed

In the present study, the activation features of phosphoric acid have been investigated using waste peach stones as the raw material in the production of granular activated carbon. Thermogravimetry/differential thermal analysis was conducted to characterize the thermal behavior of peach stone and titration method was used to evaluate the adsorption capacity of the produced activated carbon. It was observed that the iodine value of the activated carbon increased with activation temperature. However, temperatures higher than 500 degrees C caused a thermal destruction, which resulted in the decrease of the adsorption capacity. Activation longer than 1.5 h at 500 degrees C resulted in thermal degradation of the porous structure of the activated carbon. The adsorption capacity was enhanced with increasing of amounts of phosphoric acid, however, excessive phosphoric acid caused a decrease in the iodine value. In addition, it was found that the carbon yields generally decreased with activation temperature and activation time. Scanning electron microscopy analysis was conducted to observe the changes in the poros structure of the activated carbon produced in different temperatures. Activation of carbon by phosphoric acid was found to be superior to that by CaCl2 and gas activation. The activated carbon produced from peach stone was applied as an adsorbent in the treatment of synthesized wastewater containing cadmium ion and its adsorption capacity was found to be as good as that of the commercial one. PMID:15137699

Kim, Dong-Su

2004-01-01

291

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...

292

A Comparison of Defects Produced on Oxidation of Carbon Nanotubes by Acid and UV Ozone Treatment  

Microsoft Academic Search

Oxidation using ozone in the presence of ultraviolet light was used to reduce the number of defects on carbon nanotubes. Fourier transform infra red spectra showed that the treatment promotes milder oxidation in introducing carboxylic functional group than conventional acid treatment. Transmission electron microscope images suggest that ozone treated carbon nanotubes suffered reduced attrition of broken tips, bent tips and

Abu Bakar Sulong; Che Husna Azhari; Rozli Zulkifli

2009-01-01

293

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...

294

Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes  

Microsoft Academic Search

Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor\\u000a deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by\\u000a boiling in sulfuric acid solution. Various analytical techniques such as TGA\\/DSC, Raman spectroscopy, SEM, HRTEM and EDAX\\u000a were employed to investigate the morphology, graphitization and quality of

Seyedeh Z. Mortazavi; Abdul J. Novinrooz; Ali Reyhani; Soghra Mirershadi

2010-01-01

295

Blood gases  

MedlinePLUS

Values at sea level: Partial pressure of oxygen (PaO2) - 75 - 100 mmHg Partial pressure of carbon dioxide (PaCO2) - 38 - 42 mmHg Arterial blood pH of 7.38 - 7.42 Oxygen saturation (SaO2) - 94 - 100% Bicarbonate - (HCO3) - 22 - 28 mEq/L Note: mEq/L = ...

296

Solids Liquids and Gases  

NSDL National Science Digital Library

Compare and contrast the three states of matter: solids, liquids and gases. First you will begin by looking at characteristics of each solids, liquids and gasesGases, Liquids and Solids Facts. Then you will look at examples of each stateSolids, Liquids and Gases Video. Demonstrate an understanding of solids, liquids and gases by playing interactive gameSolids, Liquids and Gases Game. Graphic Organizer is here to be filled out as you learn during this lesson. Use the red ...

Salter, Ms.

2009-10-22

297

Cooperative acid-base effects with functionalized mesoporous silica nanoparticles: applications in carbon-carbon bond-formation reactions.  

PubMed

Acid-base bifunctional mesoporous silica nanoparticles (MSN) were prepared by a one-step synthesis by co-condensation of tetraethoxysilane (TEOS) and silanes possessing amino and/or sulfonic acid groups. Both the functionality and morphology of the particles can be controlled. The grafted functional groups were characterized by using solid-state (29)Si and (13)C cross-polarization/magic angle spinning (CP/MAS) NMR spectroscopy, thermal analysis, and elemental analysis, whereas the structural and the morphological features of the materials were evaluated by using XRD and N(2) adsorption-desorption analyses, and SEM imaging. The catalytic activities of the mono- and bifunctional mesoporous hybrid materials were evaluated in carbon-carbon coupling reactions like the nitroaldol reaction and the one-pot deacetalization-nitroaldol and deacetalization-aldol reactions. Among all the catalysts evaluated, the bifunctional sample containing amine and sulfonic acid groups (MSN-NNH(2)-SO(3)H) showed excellent catalytic activity, whereas the homogeneous catalysts were unable to initiate the reaction due to their mutual neutralization in solution. Therefore a cooperative acid-base activation is envisaged for the carbon-carbon coupling reactions. PMID:19569138

Shylesh, Sankaranarayanapillai; Wagner, Alex; Seifert, Andreas; Ernst, Stefan; Thiel, Werner R

2009-07-20

298

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

National Technical Information Service (NTIS)

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 produ...

J. G. Zeikus M. Jain

1993-01-01

299

COMPRESSED MEDICAL GASES GUIDELINE  

Center for Biologics Evaluation and Research (CBER)

... COMPRESSED MEDICAL GASES GUIDELINE. (REVISED) FEBRUARY 1989. ... COMPRESSED MEDICAL GASES GUIDELINE. INTRODUCTION. ... More results from www.fda.gov/drugs/guidancecomplianceregulatoryinformation/guidances

300

Carbon nanotubes and nucleic acids: tools and targets  

Microsoft Academic Search

Nucleic acids, with their intrinsic structural properties as well as their high specificity, are playing an important role in the rapid development of nano-technologies. In turn, these new technologies and their efficient performance enable fast and precise methods for detection of nucleic acids, improving the diagnosis of diseases and identification of pathogens. We discuss the use of nucleic acids to

Bibiana Onoa; Ming Zheng; Mildred S. Dresselhaus; Bruce A. Diner

2006-01-01

301

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

302

Microwave digestion and acidic treatment procedures for the purification of multi-walled carbon nanotubes  

Microsoft Academic Search

Multi-walled carbon nanotubes (MWCNTs) synthesized by thermal chemical vapor deposition have been successfully purified by using efficient microwave digestion method. Recently, various purification methods have been provided to eliminate metal catalysts and most were acid treatment procedures that take long time and damage the structure of nanotubes. Comparing to these methods, microwave digestion takes a tremendous advantage because the acid

Chieng-Ming Chen; Mi Chen; Yong-Wang Peng; Cheng-Hsiung Lin; Li-Wei Chang; Chia-Fu Chen

2005-01-01

303

Polyvinylpyrrolidone and polyethylenimine as inhibitors for the corrosion of a low carbon steel in phosphoric acid  

Microsoft Academic Search

Polarization and weight loss studies showed that both polyvinylpyrrolidonc and polyethylenimine are effective for the inhibition of low carbon steel over a wide concentration range of aqueous phosphoric acid (H3PO4) solutions. Both polymers retard the anodic and cathodic corrosion reactions with emphasis on the former. The results for uninhibited acid confirm the kinetic expression proposed by Mathur and Vasudevan.

Y. Jianguo; W. Lin; V. Otieno-Alego; D. P. Schweinsberg

1995-01-01

304

Research Paper An Examination of the Carbon Isotope Effects Associated with Amino Acid Biosynthesis  

Microsoft Academic Search

Stable carbon isotope ratios (? 13C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glu- tamine), lysine, serine, glycine, and threonine from metabolically diverse microorganisms. The microorganisms examined included fermenting bacteria, organotrophic, chemolithotrophic, phototrophic, methylotrophic, methanogenic, acetogenic, acetotrophic, and naturally occurring cryptoendolithic communities from the Dry Valleys of Antarctica. Here

JAMES H. SCOTT; DIANE M. O'BRIEN; DAVID EMERSON; HENRY SUN; GENE D. McDONALD; ANTONIO SALGADO; MARILYN L. FOGEL

305

Fracture Toughness of Carbon Nanofiber Reinforced Polylactic Acid at Room and Elevated Temperatures  

Microsoft Academic Search

Summary Polylactic acid (PLA) is a biodegradable plastic made from lactic acid, and can be produced by renewable raw materials. The mechanical properties of PLA are, however, not sufficient for structural materials. In our study,carbon nanofiber rein- forced PLA was fabricated to overcome the deficiency of PLA and the mechanical properties were measured at room and elevated temperatures. Vapor grown

Y. Shimamura; Y. Shibata; K. Tohgo; H. Araki

2008-01-01

306

A comparative study of solid carbon acid catalysts for the esterification of free fatty acids for biodiesel production. Evidence for the leaching of colloidal carbon.  

PubMed

The preparation of a variety of sulfonated carbons and their use in the esterification of oleic acid is reported. All sulfonated materials show some loss in activity associated with the leaching of active sites. Exhaustive leaching shows that a finite amount of activity is lost from the carbons in the form of colloids. Fully leached catalysts show no loss in activity upon recycling. The best catalysts; 1, 3, and 6; show initial TOFs of 0.07s(-1), 0.05s(-1), and 0.14s(-1), respectively. These compare favorably with literature values. Significantly, the leachate solutions obtained from catalysts 1, 3, and 6, also show excellent esterification activity. The results of TEM and catalyst poisoning experiments on the leachate solutions associate the catalytic activity of these solutions with carbon colloids. This mechanism for leaching active sites from sulfonated carbons is previously unrecognized. PMID:24021721

Deshmane, Chinmay A; Wright, Marcus W; Lachgar, Abdessadek; Rohlfing, Matthew; Liu, Zhening; Le, James; Hanson, Brian E

2013-08-20

307

Preparation and characterization of sulfonic acid-functionalized single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

A strategy for the functionalization of single-walled carbon nanotubes is reported. The synthesis involved the conversion of fluorinated single-walled carbon nanotubes to the thiolated derivative assisted by phosphorous pentasulfide. The thiol group is then quantitatively oxidized to the sulfonic acid group. The extent of oxidation of the thiol precursor is confirmed using X-ray photoelectron spectroscopy, which proved to be immensely useful to discriminate between the -SH and -SO3H with a chemical shift for the sulfur 2p (approx. 5 eV). The functionalized carbon nanotubes were further characterized by infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy which revealed a significant change in morphology between the fluoro carbon nanotubes, the thiol and sulfonic acid-modified carbon nanotubes.

Adams, Luqman; Oki, Aderemi; Grady, Tony; McWhinney, Hylton; Luo, Zhiping

2009-02-01

308

Inhibition Effect of Dodecylamine on Carbon Steel Corrosion in Hydrochloric Acid Solution  

NASA Astrophysics Data System (ADS)

Dodecylamine spontaneously adsorbs on carbon steel via its polar group (-NH2) in hydrochloric acid solution. Furthermore, it forms a monolayer film on carbon steel surface. The inhibition mechanism of dodecylamine for carbon steel is geometric blocking effect. The adsorption of dodecylamine on carbon steel surface follows Arrhenius equation. The adsorption slightly increases activated energy, but greatly reduces pre-exponential factor value. Atomic force microscopy force curves indicate that at the area without adsorbed dodecylamine, no obvious adhere force occurs. At the area with adsorbed dodecylamine, however, an average 1.3 nN adhere force is observed.

Chen, Zhenyu; Huang, Ling; Qiu, Yubing; Guo, Xingpeng

2012-12-01

309

Oxygen-18 incorporation into malic acid during nocturnal carbon dioxide fixation in crassulacean acid metabolism plants. A new approach to estimating in vivo carbonic anhydrase activity.  

PubMed

Crassulacean acid metabolism (CAM) plants fix carbon dioxide at night by the carboxylation of phosphoenolpyruvate. If CO2 fixation is conducted with 13C18O2 , then in the absence of carbonic anhydrase, the malate formed by dark CO2 fixation should also contain high levels of carbon-13 and oxygen-18. Conversely, if carbonic anhydrase is present and highly active, oxygen exchange between CO2 and cellular H2O will occur more rapidly than carboxylation, and the [13C] malate formed will contain little or no oxygen-18 above the natural abundance level. The presence of oxygen-18 in these molecules can be detected either by nuclear magnetic resonance (using the oxygen-18 effect on the carbon-13 chemical shift of the carboxyl carbon) or by mass spectrometry (comparing the ions at three and five units above the molecular weight with that one unit above). Studies of phosphoenolpyruvate carboxylase in the presence and absence of carbonic anhydrase in vitro confirm the validity of the method. When CAM plants are studied by this method, we find that most species show incorporation of a significant amount of oxygen-18. Comparison of these results with results of isotope fractionation and gas exchange studies permits calculation of the in vivo activity of carbonic anhydrase toward HCO-3 compared with that of phosphoenolpyruvate carboxylase. The ratio (carbonic anhydrase activity/phosphoenolpyruvate carboxylase activity) is species dependent and varies from a low of about 7 for Ananas comosus to values near 20 for Hoya carnosa and Bryophyllum pinnatum , 40 for Kalancho daigremontiana , and 100 or greater for Bryophyllum tubiflorum , Kalancho serrata, and Kalancho tomentosa. Carbonic anhydrase activity increases relative to phosphoenolpyruvate carboxylase activity at higher temperature. PMID:6427227

Holtum, J A; Summons, R; Roeske, C A; Comins, H N; O'Leary, M H

1984-06-10

310

From the First Measurements of Atmospheric Carbon Dioxide During the IGY to the Global Annual Greenhouse Gas Index in 2006: The Evolution of the Global Observing Network for Greenhouse Gases.  

NASA Astrophysics Data System (ADS)

During the International Geophysical Year, Dr. Charles "Dave" Keeling instituted both air sample collections at the South Pole in Antarctica and continuous carbon dioxide measurements with an infrared analyzer at the Mauna Loa Observatory in Hawaii. Both of these locations were later to become Observatories of the U.S. National Oceanic and Atmospheric Administration (NOAA), following its formation in 1970, and the pioneering measurements of Dave Keeling continued to be supported by NOAA at these sites until this day. In addition to instituting Observatories at key background locations (Pt. Barrow, Alaska; American Samoa; and more recently Trinidad Head, California, in addition to the Hawaii and Antarctic sites) the forerunners of NOAA/ESRL also began a global cooperative air sampling network in the late 1960's. The air samples were analyzed for carbon dioxide and other gases in the Boulder, Colorado laboratories. With the help of many people in many nations, this network has grown to the largest such effort in the world, numbering about 90 sites, including three ship routes, at present. In 1996, data from this network and from other networks around the world formed the basis of GLOBALVIEW, a web-based collection of carbon dioxide and methane data used extensively with transport models to determine global carbon dioxide sources and sinks. This data set is available at http://www.cmdl.noaa.gov/ccgg/globalview/index.html . In 2004, the global measurements of all the long-lived greenhouse gases, including carbon dioxide, methane, nitrous oxide, the chlorofluorocarbons, and ten minor halogen gases were condensed into a simple index, the "Annual Greenhouse Gas Index" (AGGI) by summing their radiative climate forcing since the pre-industrial era (taken as 1750). The NOAA AGGI is designed to enhance the connection between scientists and society by providing a normalized standard that can be easily understood and followed. The contribution of long-lived greenhouse gases to climate forcing is well understood by scientists and has been reported through a range of national and international assessments. Nevertheless, the language of scientists (for example, watts per square meter per year) often eludes policy makers, educators, and the general public. This index is designed to help bridge that gap.

Hofmann, D. J.; Butler, J. H.; Dlugokencky, E. J.; Elkins, J. W.; Masarie, K.; Montzka, S. A.; Tans, P. P.

2006-05-01

311

Fluid-velocity and reaction-rate effects during carbonate acidizing  

SciTech Connect

Coreflood experiments were performed and a network model developed to study flow and matrix dissolution in carbonates during acidizing treatments. Wormholing in carbonates is controlled by the relative rates of flow and dissolution, which are characterized by a Damkoehler number, N/sub Da/, for the process. Acid penetrates only as a result of wormholing, and well-defined channels will not form if N/sub Da/ is either very high or very low. Effects of acidizing differ markedly between limestone and dolomite because of differences in the mineral dissolution rates.

Hoefner, M.L.; Fogler, H.S.

1989-02-01

312

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob  

NASA Astrophysics Data System (ADS)

Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (SBET = 2081 m2/g, Vtot = 1.1 cm3/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Sych, N. V.; Trofymenko, S. I.; Poddubnaya, O. I.; Tsyba, M. M.; Sapsay, V. I.; Klymchuk, D. O.; Puziy, A. M.

2012-11-01

313

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

314

Metabolic carbon fluxes and biosynthesis of polyhydroxyalkanoates in Ralstonia eutropha on short chain fatty acids.  

PubMed

Short chain fatty acids such as acetic, propionic, and butyric acids can be synthesized into polyhydroxyalkanoates (PHAs) by Ralstonia eutropha. Metabolic carbon fluxes of the acids in living cells have significant effect on the yield, composition, and thermomechanical properties of PHA bioplastics. Based on the general knowledge of central metabolism pathways and the unusual metabolic pathways in R. eutropha, a metabolic network of 41 bioreactions is constructed to analyze the carbon fluxes on utilization of the short chain fatty acids. In fed-batch cultures with constant feeding of acid media, carbon metabolism and distribution in R. eutropha were measured involving CO2, PHA biopolymers, and residual cell mass. As the cells underwent unsteady state metabolism and PHA biosynthesis under nitrogen-limited conditions, accumulative carbon balance was applied for pseudo-steady-state analysis of the metabolic carbon fluxes. Cofactor NADP/NADPH balanced between PHA synthesis and the C3/C4 pathway provided an independent constraint for solution of the underdetermined metabolic network. A major portion of propionyl-CoA was directed to pyruvate via the 2-methylcitrate cycle and further decarboxylated to acetyl-CoA. Only a small amount of propionate carbon (<15% carbon) was directly condensed with acetyl-CoA for 3-hydroxyvalerate. The ratio of glyoxylate shunt to TCA cycle varies from 0 to 0.25, depending on the intracellular acetyl-CoA level and acetic acid in the medium. Malate is the node of the C3/C4 pathway and TCA cycle and its decarboxylation to dehydrogenation ranges from 0.33 to 1.28 in response to the demands on NADPH and oxaloacetate for short chain fatty acids utilization. PMID:15296425

Yu, Jian; Si, Yingtao

315

Reductive desorption of sulfuric acid formed on the carbon catalyst in flue gas desulfurization (FGD)  

Microsoft Academic Search

Reductive desorption of sulfuric acid formed on the carbon catalyst in flue gas desulfurization (FGD) by heating with hydrogen at 3: 200°C converted the acid to gas-phase sulfur dioxide with a significant loss of the acid to hydrogen sulfide and elemental sulfur. These side reactions were suppressed and the temperature required for SO recovery was reduced by impregnating the charcoal

S. Yoshizawa; A. Karagiri; K. Watanabe

1979-01-01

316

Wet-spinning of neat single-walled carbon nanotube fiber from 100+% sulfuric acid  

Microsoft Academic Search

Single-Walled Carbon Nanotubes (SWNT) have been found to have excellent solubility in super acids such as 100+% H2SO4, and chlorsulfonic acid. The solutions display liquid crystalline behavior at high concentrations in super acids. Traditional wet-spinning method has been applied to SWNTs to make fibers from SWNTs only with the assistance of 100+% H2SO 4 (neat SWNT fibers). Extensive conditions, including

Fan Hua

2008-01-01

317

Simultaneous quantitative determination of deuterium- and carbon-13-labeled essential fatty acids in rat plasma  

Microsoft Academic Search

This study reports methods for the quantitative determination of stable isotope-labeled essential fatty acids (EFAs) as well as an experiment in which deuterium-labeled linoleic acid (18:2n-6) and ? -linolenic acid (18:3n-3) were compared with those labeled with carbon-13 in rat plasma in vivo. Standard curves were constructed to compensate for concentration and plasma matrix effects. It was observed that endogenous

Yu Hong Lin; Robert J. Pawlosky; Norman Salem

2005-01-01

318

An amperometric sensor for uric acid based on ordered mesoporous carbon-modified pyrolytic graphite electrode  

Microsoft Academic Search

A novel amperometric sensor for uric acid based on ordered mesoporous carbon modified pyrolytic graphite electrode was developed.\\u000a Uric acid oxidation was easily catalyzed by this electrode in a phosphate buffer solution at pH 7.0, with an anodic potential\\u000a decrease about 140 mV compared to bare pyrolytic graphite electrode. The uric acid level was determined by the amperometric\\u000a method, at

Yonggen Ma; Guangzhi Hu; Shijun Shao; Yong Guo

2009-01-01

319

A theoretical study of some hydroxamic acids as corrosion inhibitors for carbon steel  

Microsoft Academic Search

The corrosion inhibition characteristics of two hydroxamic acids, i.e., oxalyl-dihydroxamic acid (C2) and pimeloyl-1,5-di-hydroxamic acid (C7), on carbon steel has been studied using density functional theory (DFT). Quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), and energy gap (?E) have been calculated using B3LYP\\/6-31+G?? basis set. The relationship between the inhibition

Gkhan Gece; Semra Bilgi

2010-01-01

320

Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System  

PubMed Central

Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1) system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source) and keto acids (oxylic acid sources). In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of lifes origin.

Fujioka, Kouki; Futamura, Yasuhiro; Shiohara, Tomoo; Hoshino, Akiyoshi; Kanaya, Fumihide; Manome, Yoshinobu; Yamamoto, Kenji

2009-01-01

321

Reworking of amino acid in marine sediments: Stable carbon isotopic composition of amino acids in sediments along the Washington coast  

Microsoft Academic Search

The stable carbon isotopic composition of nine individual amino acids were investigated in phytoplankton and zooplankton, estuarine plankton, terrigenous material, marine fecal material, and clay mineral isolates collected along the Washington coast. The clay fraction was isolated from suspended sediments of the Columbia River (the mineral source) and three shelf and slope stations (mineral deposition sites). In the sediments, terrigenous

Richard G. Keil; Marilyn L. Fogel

2001-01-01

322

Heterogeneous reactions of gaseous hydrogen peroxide on pristine and acidic gas-processed calcium carbonate particles: Effects of relative humidity and surface coverage of coating  

NASA Astrophysics Data System (ADS)

Atmospheric aging appears to alter physical and chemical properties of mineral dust aerosol and thus its role as reactive surface in the troposphere. Yet, previous studies in the atmosphere have mainly focused on the pristine surfaces of mineral dust aerosol, and the reactivity of aged mineral dust toward atmospheric trace gases is poorly recognized. This work presents the first laboratory investigation of heterogeneous reactions of gaseous hydrogen peroxide (H2O2), an important atmospheric oxidant, on the surfaces of HNO3 and SO2-processed calcium carbonate particles as surrogates of atmospheric mineral dust aged by acidic trace gases. It is found that the processing of the calcium carbonate particles with HNO3 and SO2 has a strong impact on their reactivity toward H2O2. On HNO3-processed particles, the presence of nitrate acts to either decrease or increase H2O2 uptake, greatly depending on RH and surface coverage of nitrate. On SO2-processed particles, the presence of surface sulfite appears to enhance the intrinsic reactivity of the mineral particles due to its affinity for H2O2, and the uptake of H2O2 increases significantly relative to the pristine particles, in particular at high RH. The mechanisms for heterogeneous reactions of H2O2 with these processed particles are discussed, as well as their potential implications on tropospheric chemistry. The results of our study suggest that the reactivity of mineral dust aerosol toward H2O2 and maybe other trace gases is markedly dependent on the chemical composition and coverage of the coatings as well as ambient RH, and thus will vary considerably in different polluted air masses.

Zhao, Yue; Chen, Zhongming; Shen, Xiaoli; Huang, Dao

2013-03-01

323

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

324

Synthesis of carbon\\/EMD composite from carbon-suspended sulfuric acid and manganese sulfate bath  

Microsoft Academic Search

A study has been made of the electrodeposition of MnO2 on a titanium anode from a carbon or carbon\\/MnO2 composite suspended in a H2SO4-MnSO4 bath. Electrolytic manganese dioxide (EMD) containing acetylene black or vapor-grown carbon fiber shows excellent alkaline battery performance and good grindability. Nevertheless, passivation of the titanium anode sometimes occurs during electrolysis at a current density of 1

Gen-Pei Piao; Masaki Yoshio; Hideyuki Noguchi; Akiya Kozawa

1994-01-01

325

Fumaric acid: an overlooked form of fixed carbon in Arabidopsis and other plant species  

SciTech Connect

Photoassimilates are used by plants for production of energy, as carbon skeletons and in transport of fixed carbon between different plant organs. Many studies have been devoted to characterizing the factors that. regulate photoassimilate concentrations in different plant species. Most studies examining photoassimilate concentrations in C{sub 3} plants have focused on analyzing starch and soluble sugars. However, work presented here demonstrates that a number of C{sub 3} plants, including the popular model organism Arabidopsis thaliana (L.) Heynh., and agriculturally important plants, such as soybean [Glycine ma (L.) Merr.], contain significant quantities of furnaric acid. In fact, furnaric acid can accumulate to levels of several mg per g fresh weight in A-abidopsis leaves, often exceeding starch and soluble sugar levels. Furnaric acid is a component of the tricarboxylic acid cycle and, like starch and soluble sugars, can be metabolized to yield energy and carbon skeletons for production of other compounds. Fumaric acid concentrations increase with plant age and light intensity in Arabidopsis leaves. Arabidopsis phloem exudates contain significant quantities of fumaric acid, raising the possibility that fumaric acid may function in carbon transport.

Chia, D.W.; Yoder, T.J.; Reiter, W.D.; Gibson, S.I.

2000-10-01

326

Carbon and hydrogen isotopic evidence for the origin of combustible gases in water-supply wells in north-central Pennsylvania  

USGS Publications Warehouse

The origin of the combustible gases in groundwater from glacial-outwash and fractured-bedrock aquifers was investigated in northern Tioga County, Pennsylvania. Thermogenic methane (CH4) and ethane (C2H6) and microbial CH4 were found. Microbial CH4 is from natural in situ processes in the shale bedrock and occurs chiefly in the bedrock aquifer. The ?13C values of CH4 and C2H6 for the majority of thermogenic gases from water wells either matched or were between values for the samples of non-native storage-field gas from injection wells and the samples of gas from storage-field observation wells. Traces of C2H6 with microbial CH4 and a range of C and H isotopic compositions of CH4 indicate gases of different origins are mixing in sub-surface pathways; gas mixtures are present in groundwater. Pathways for gas migration and a specific source of the gases were not identified. Processes responsible for the presence of microbial gases in groundwater could be elucidated with further geochemical study.

Rvsz, K. M.; Breen, K. J.; Baldassare, A. J.; Burruss, R. C.

2010-01-01

327

Chemical and biological consequences of using carbon dioxide versus acid additions in ocean acidification experiments  

USGS Publications Warehouse

Use of different approaches for manipulating seawater chemistry during ocean acidification experiments has confounded comparison of results from various experimental studies. Some of these discrepancies have been attributed to whether addition of acid (such as hydrochloric acid, HCl) or carbon dioxide (CO2) gas has been used to adjust carbonate system parameters. Experimental simulations of carbonate system parameter scenarios for the years 1766, 2007, and 2100 were performed using the carbonate speciation program CO2SYS to demonstrate the variation in seawater chemistry that can result from use of these approaches. Results showed that carbonate system parameters were 3 percent and 8 percent lower than target values in closed-system acid additions, and 1 percent and 5 percent higher in closed-system CO2 additions for the 2007 and 2100 simulations, respectively. Open-system simulations showed that carbonate system parameters can deviate by up to 52 percent to 70 percent from target values in both acid addition and CO2 addition experiments. Results from simulations for the year 2100 were applied to empirically derived equations that relate biogenic calcification to carbonate system parameters for calcifying marine organisms including coccolithophores, corals, and foraminifera. Calculated calcification rates for coccolithophores, corals, and foraminifera differed from rates at target conditions by 0.5 percent to 2.5 percent in closed-system CO2 gas additions, from 0.8 percent to 15 percent in the closed-system acid additions, from 4.8 percent to 94 percent in open-system acid additions, and from 7 percent to 142 percent in open-system CO2 additions.

Yates, Kimberly K.; DuFore, Christopher M.; Robbins, Lisa L.

2013-01-01

328

Spectroscopic detection of the most stable carbonic acid, cis-cis H2CO3  

NASA Astrophysics Data System (ADS)

Carbonic acid had not been detected by any spectroscopic means for a long period. Recently, we have reported the detection of its second most stable conformer, cis-trans H2CO3, as the first spectroscopic detection of the isolated carbonic acid molecule. In the present work, the most stable conformer of carbonic acid, cis-cis H2CO3, in the gas phase has been successfully produced in a supersonic jet using a pulsed discharge nozzle, and pure rotational transitions of this molecule have been observed by a Fourier-transform microwave spectrometer. In addition to cis-cis H2CO3, its deuterated isotopologue, cis-cis D2CO3, has been observed, yielding the r0 structure of the cis-cis conformer. Furthermore, hyperfine constants of the deuterated cis-trans conformers were also determined. The two structures for the stable isolated carbonic acid molecule, those of the cis-cis and cis-trans conformers, are considered to provide basic information for the understanding of chemical reactions involving carbonic acid The present result is accurate enough to be used in radio astronomical observations, where the ortho/para ratio of cis-cis H2CO3 may be used as an important probe of interstellar chemistry.

Mori, Tetsuya; Suma, Kohsuke; Sumiyoshi, Yoshihiro; Endo, Yasuki

2011-01-01

329

[Preparation, characterization and adsorption performance of mesoporous activated carbon with acidic groups].  

PubMed

Mesoporous activated carbons containing acidic groups were prepared with cotton stalk based fiber as raw materials and H3PO4 as activating agent by one step carbonization method. Effects of impregnation ratio, carbonization temperature and heat preservation time on the yield, elemental composition, oxygen-containing acid functional groups and adsorptive capacity of activated carbon were studied. The adsorption capacity of the prepared activated carbon AC-01 for p-nitroaniline and Pb(II) was studied, and the adsorption mechanism was also suggested according to the equilibrium experimental results. The maximum yield of activated carbons prepared from cotton stalk fiber reached 35.5% when the maximum mesoporous volume and BET surface area were 1.39 cm3 x g(-1) and 1 731 m2 x g(-1), respectively. The activated carbon AC-01 prepared under a H3 PO4/precursor ratio of 3:2 and activated at 900 degrees C for 90 min had a total pore volume of 1.02 cm3 x g(-1), a micoporous ratio of 31%, and a mesoporous ratio of 65%. The pore diameter of the mesoporous activated carbon was mainly distributed in the range of 2-5 nm. The Langmuir maximum adsorption capacities of Pb(II) and p-nitroaniline on cotton stalk fiber activated carbon were 123 mg x g(-1) and 427 mg x g(-1), respectively, which were both higher than those for commercial activated carbon fiber ACF-CK. The equilibrium adsorption experimental data showed that mesopore and oxygen-containing acid functional groups played an important role in the adsorption. PMID:23947073

Li, Kun-Quan; Li, Ye; Zheng, Zheng; Zhang, Yu-Xuan

2013-06-01

330

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

2010-01-06

331

SORPTION OF MERCURY SPECIES BY ACTIVATED CARBONS AND CALCIUM-BASES SORBENTS: EFFECT OF TEMPERATURE, MERCURY CONCENTRATION AND ACID GASES  

EPA Science Inventory

Bench-scale studies of mercury/sorbent reactions were conducted to understand mechanistic limitations of field-scale attempts to reduce emissions of mercury from combustion processes. The effects of temperature (60 - 140 degrees C), sulfur dioxide (SO2, 1000 ppm ), hydrogen chlor...

332

The use of acetic acid as a source of carbon by cultured Chondrus crispus (Gigartinales, Rhodophyta) stackhouse  

Microsoft Academic Search

When growing seaweeds in tanks, pH and carbon source supply have to be controlled in order to maximize photosynthesis. pH can be controlled either by adding various inorganic acids which requires the extra addition of carbon, or by combining pH control and carbon source with for instance CO2 or an organic acid such as acetic acid (CH3COOH). We have found

Mireille A. Amat; Jean-Paul Braud

1993-01-01

333

Carbon doping of MgB2 by toluene and malic-acid-in-toluene  

NASA Astrophysics Data System (ADS)

The decomposition of malic acid (C4H6O5) 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 (C7H8) 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 MgB2 monofilamentary wires established that the toluene/malic acid doped sample had the highest Bc2. However, the toluene-only sample had the highest transport Jc 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

334

Calcium stimulation of gastrin and gastric acid secretion: effect of small doses of calcium carbonate.  

PubMed Central

Oral calcium carbonate (0-5 g, pH 9-4) increased serum gastrin and gastric acid output with slight but insignificant change in serum calcium. A similar rise in serum calcium during an intravenous infusion of calcium gluconate failed to increase serum gastrin and gastric acid output. Both intragastric calcium actions were abolished by acidification of the calcium carbonate solution (pH 1-0). The increase in serum gastrin and gastric acid output after intragastric calcium carbonate was not affected, however, by a simultaneous intraduodenal acid load. Equivalent neutralising doses of magnesium hydroxide (pH 9-4) did not increase serum gastrin and gastric acid output above basal levels, whereas antral acidification with 20 ml 0-1 N HCl resulted in a slight decrease in serum gastrin. Intraduodenal calcium carbonate (pH 3-0) also increased serum gastrin and gastric acid output, whereas an equivalent volume of intraduodenal saline (pH 3-0) had no effect. These findings indicate that calcium increases serum gastrin by local stimulation of antral and duodenal mucosa. They also suggest that the action of calcium on gastric secretion is partly mediated by gastrin.

Behar, J; Hitchings, M; Smyth, R D

1977-01-01

335

Field evaluation of gelled acid for carbonate formations  

SciTech Connect

A new gelled acid was evaluated in W. Texas, S.E. New Mexico, and Oklahoma. The evaluation determined how successful a gelled acid, prepared from xanthan polymer, would be in the following formations: Ellenburger, Blinebry, San Andres, Clearfork, Canyon Lime, Strawn Lime, Grayburg, Devonian, Drinkard Dolomite, Viola and Chester. Treatment depths vary from 4000 to 22,000 ft. Treatment temperatures vary from 70 to 310 F. Treatments were performed on both oil and gas wells. The age of the wells stimulated varies from new to 30 yr old. The concentration of gelled acid remained constant at 15% HCl. The concentration of gelling agent remained constant at 60 lb/1000 gal. The size of the treatments varied from 5000 to 80,000 gal of gelled acid. More than 20 treatments are summarized. Production figures for the well treated are summarized. Production figures for the wells treated are discussed, as well as pertinent related information.

Church, D.C.; Quisenberry, J.L.; Fox, K.B.

1981-01-01

336

Poly(2,5-benzoxazole)\\/carbon nanotube composites via in situ polymerization of 3-amino-4-hydroxybenzoic acid hydrochloride in a mild poly(phosphoric acid)  

Microsoft Academic Search

Poly(2,5-benzoxzole) (ABPBO)\\/carbon nanotube (CNT) composites were prepared via in situ polycondensation of protonated AB monomer, 3-amino-4-hydroxybenzoic acid hydrochloride, in a mildly acidic poly(phosphoric acid) medium. In situ generated hydrochloric acid during the dehydrochlorination process provided additional acidity to the reaction medium. The enhanced acidity was advantageous for both the purification and dispersion of CNTs. Specifically, it was evident for the

Soo-Mi Eo; Se-Jin Oh; Loon-Seng Tan; Jong-Beom Baek

2008-01-01

337

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

NASA Astrophysics Data System (ADS)

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 (?13CTC). TC and WSOC showed a large increase during the heavy forest fire event. At the same period, dicarboxylic acids, dominated by oxalic (C2) followed by succinic (C4) and malonic (C3) acids, also showed a concentration increase. Furthermore, the ?13CTC showed a decrease from ca. -25.5 to -27.5 during an intensified forest fire event, suggesting an addition of organic aerosols derived from C3 plants whose ?13C are lighter. These results indicate that the aerosol particles in Southeast Asia were significantly affected by the combustion processes of vegetations during the 1997 Indonesian forest fires that were extensively induced by El Nin event.

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

338

Preparation and characterization of sulfonic acid-functionalized single-walled carbon nanotubes  

Microsoft Academic Search

A strategy for the functionalization of single-walled carbon nanotubes is reported. The synthesis involved the conversion of fluorinated single-walled carbon nanotubes to the thiolated derivative assisted by phosphorous pentasulfide. The thiol group is then quantitatively oxidized to the sulfonic acid group. The extent of oxidation of the thiol precursor is confirmed using X-ray photoelectron spectroscopy, which proved to be immensely

Luqman Adams; Aderemi Oki; Tony Grady; Hylton McWhinney; Zhiping Luo

2009-01-01

339

SYNTHESIS OF NOVEL HYDROPHILIC POLY(ESTER-CARBONATES) CONTAINING PENDENT CARBOXYLIC ACID GROUPS  

Microsoft Academic Search

A functional cyclic carbonate, 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC), was utilized in the synthesis of novel poly(ester-carbonates) containing pendent carboxylic acid groups. Copolymers with ?-caprolactone (CL) and L-lactide (LLA) were synthesized by ring-opening polymerization (ROP) using either an Al-alkoxide (solution) or Sn(Oct)2-alcohol (bulk) initiating system. Analysis of the copolymers revealed a random distribution of the comonomer units along the polymer chain. The copolymers

Robson F. Storey; Brian D. Mullen; Kim M. Melchert

2001-01-01

340

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

341

Safe Recombining of Gases From Storage Batteries: Gas recombination device promises to make the lead/acid battery safe for power industry.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A hydrogen/oxygen recombination device (HORD) recombines gases catalytically to produce water at nearly 100 percent efficiency, thus eliminating the danger of an exp...

1982-01-01

342

Adsorption of Off?Gases from Steam Methane Reforming (H2, CO2, CH4, CO and N2) on Activated Carbon  

Microsoft Academic Search

Hydrogen is the energy carrier of the future and could be employed in stationary sources for energy production. Commercial sources of hydrogen are actually operating employing the steam reforming of hydrocarbons, normally methane. Separation of hydrogen from other gases is performed by Pressure Swing Adsorption (PSA) units where recovery of high?purity hydrogen does not exceed 80%.In this work we report

Carlos A. Grande; Filipe V. S. Lopes; Ana M. Ribeiro; Jos M. Loureiro; Alrio E. Rodrigues

2008-01-01

343

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.; SNchez-Polo, M.

2003-09-01

344

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

345

CNG acid gas removal process isolates environmental contaminants from crude coal gas  

SciTech Connect

Carbon dioxide, hydrogen sulfide, carbonyl sulfide, and numerous other undersirable contaminants, can be effectively removed from crude coal gas by current acid gas removal (AGR) technology. However, the separation of absorbed acid gases from the AGR absorbent, and the simultaneous or subsequent sharp separation of sulfur-containing compounds and other contaminants from carbon dioxide which is necessary to prevent objectionable environmental emissions, are difficult to achieve with existing AGR technology. The CNG AGR Process described here concentrates absorbed acid gases and other contaminants, and regenerates pure AGR absorbent, by triplepoint crystallization of carbon dioxide.

Auyang, L.; Cook, W.J.; Liv, Y.C.; Siwajek, L.

1984-08-01

346

An examination of the carbon isotope effects associated with amino acid biosynthesis.  

PubMed

Stable carbon isotope ratios (delta(13)C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glutamine), lysine, serine, glycine, and threonine from metabolically diverse microorganisms. The microorganisms examined included fermenting bacteria, organotrophic, chemolithotrophic, phototrophic, methylotrophic, methanogenic, acetogenic, acetotrophic, and naturally occurring cryptoendolithic communities from the Dry Valleys of Antarctica. Here we demonstrated that reactions involved in amino acid biosynthesis can be used to distinguish amino acids formed by life from those formed by nonbiological processes. The unique patterns of delta(13)C imprinted by life on amino acids produced a biological bias. We also showed that, by applying discriminant function analysis to the delta(13)C value of a pool of amino acids formed by biological activity, it was possible to identify key aspects of intermediary carbon metabolism in the microbial world. In fact, microorganisms examined in this study could be placed within one of three metabolic groups: (1) heterotrophs that grow by oxidizing compounds containing three or more carbon-to-carbon bonds (fermenters and organotrophs), (2) autotrophs that grow by taking up carbon dioxide (chemolitotrophs and phototrophs), and (3) acetoclastic microbes that grow by assimilation of formaldehyde or acetate (methylotrophs, methanogens, acetogens, and acetotrophs). Furthermore, we demonstrated that cryptoendolithic communities from Antarctica grouped most closely with the autotrophs, which indicates that the dominant metabolic pathways in these communities are likely those utilized for CO(2 )fixation. We propose that this technique can be used to determine the dominant metabolic types in a community and reveal the overall flow of carbon in a complex ecosystem. PMID:17155886

Scott, James H; O'Brien, Diane M; Emerson, David; Sun, Henry; McDonald, Gene D; Salgado, Antonio; Fogel, Marilyn L

2006-12-01

347

An Examination of the Carbon Isotope Effects Associated with Amino Acid Biosynthesis  

NASA Astrophysics Data System (ADS)

Stable carbon isotope ratios (?13C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glutamine), lysine, serine, glycine, and threonine from metabolically diverse microorganisms. The microorganisms examined included fermenting bacteria, organotrophic, chemolithotrophic, phototrophic, methylotrophic, methanogenic, acetogenic, acetotrophic, and naturally occurring cryptoendolithic communities from the Dry Valleys of Antarctica. Here we demonstrated that reactions involved in amino acid biosynthesis can be used to distinguish amino acids formed by life from those formed by nonbiological processes. The unique patterns of ?13C imprinted by life on amino acids produced a biological bias. We also showed that, by applying discriminant function analysis to the ?13C value of a pool of amino acids formed by biological activity, it was possible to identify key aspects of intermediary carbon metabolism in the microbial world. In fact, microorganisms examined in this study could be placed within one of three metabolic groups: (1) heterotrophs that grow by oxidizing compounds containing three or more carbon-to-carbon bonds (fermenters and organotrophs), (2) autotrophs that grow by taking up carbon dioxide (chemolitotrophs and phototrophs), and (3) acetoclastic microbes that grow by assimilation of formaldehyde or acetate (methylotrophs, methanogens, acetogens, and acetotrophs). Furthermore, we demonstrated that cryptoendolithic communities from Antarctica grouped most closely with the autotrophs, which indicates that the dominant metabolic pathways in these communities are likely those utilized for CO2 fixation. We propose that this technique can be used to determine the dominant metabolic types in a community and reveal the overall flow of carbon in a complex ecosystem.

Scott, James H.; O'Brien, Diane M.; Emerson, David; Sun, Henry; McDonald, Gene D.; Salgado, Antonio; Fogel, Marilyn L.

2006-12-01

348

Dissolution rates of carbonated hydroxyapatite in hydrochloric acid.  

PubMed

Osteoclasts have been shown to dissolve efficiently and effectively the mineral phase of bone by locally controlling the environment surrounding the cell. Although this mineral phase has been identified and well characterized as carbonated hydroxyapatite, there is little understanding of the factors that affect the dissolution properties of this mineral phase. Mimicking the mechanism by which osteoclasts dissolve the mineral phase of bone may provide insight into methods for the decalcification of atherosclerotic mineral deposits in the vascular system. Accordingly, a detailed characterization of the effects of various chemical and mechanical parameters on the dissolution of carbonated hydroxyapatite mineral was investigated in this study. Increases in the mineral dissolution rate (2-10 times) were associated with increases in dissolving solution [H+], osmolality, temperature, and flow rate. Mineral dissolution rate increases (5-8 times) were associated with greater surface area of the mineral and mechanical agitation of the dissolving solution. PMID:11771694

Hankermeyer, Christine R; Ohashi, Kevin L; Delaney, David C; Ross, John; Constantz, Brent R

2002-02-01

349

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 Earths radiative heat balance. Nevertheless, analytical procedures to measure BC are inconsistent, giving a non-systematic variation by factors of 14571 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

350

Activated Carbon Production from Date Stones Using Phosphoric Acid  

Microsoft Academic Search

The effects of activation time and activation temperature on the yield and the adsorptive capacity towards iodine were studied. The yield and the quality of the activated carbon prepared by using H3PO4 were compared with that prepared from date stones using the same equipment, and under similar conditions by using ZnCl2 as an oxidizing agent. The iodine number for the

F. Al-Qaessi; L. Abu-Farah

2010-01-01

351

One-Pot synthesis of phosphorylated mesoporous carbon heterogeneous catalysts with tailored surface acidity  

SciTech Connect

Soft-templated phosphorylated mesoporous carbons with homogeneous distributions of phosphate groups were prepared by a 'one-pot' synthesis method using mixtures of phosphoric acid with hydrochloric, or nitric acids in the presence of Pluronic F127 triblock copolymer. Adjusting the various ratios of phosphoric acid used in these mixtures resulted in carbons with distinct adsorption, structural and surface acidity properties. The pore size distributions (PSDs) from nitrogen adsorption at -196 C showed that mesoporous carbons exhibit specific surface areas as high as 551 m{sup 2}/g and mesopores as large as 13 nm. Both structural ordering of the mesopores and the final phosphate contents were strongly dependent on the ratios of H{sub 3}PO{sub 4} in the synthesis gels, as shown by transmission electron microscopy (TEM), X-ray photoelectron (XPS) and energy dispersive X-ray spectroscopy (EDS). The number of surface acid sites determined from temperature programmed desorption of ammonia (NH{sub 3}-TPD) were in the range of 0.3-1.5 mmol/g while the active surface areas are estimated to comprise 5-54% of the total surface areas. Finally, the conversion temperatures for the isopropanol dehydration were lowered by as much as 100 C by transitioning from the least acidic to the most acidic catalysts surface.

Fulvio, Pasquale F [ORNL; Mahurin, Shannon Mark [ORNL; Mayes, Richard T [ORNL; Bauer, Christopher [ORNL; Wang, Xiqing [ORNL; Veith, Gabriel M [ORNL; Dai, Sheng [ORNL

2012-01-01

352

Carbon nanotubes as electronic interconnects in solid acid fuel cell electrodes.  

PubMed

Carbon nanotubes have been explored as interconnects in solid acid fuel cells to improve the link between nanoscale Pt catalyst particles and macroscale current collectors. The nanotubes were grown by chemical vapor deposition on carbon paper substrates, using nickel nanoparticles as the catalyst, and were characterized using scanning electron microscopy and Raman spectroscopy. The composite electrode material, consisting of CsH2PO4, platinum nanoparticles, and platinum on carbon-black nanoparticles, was deposited onto the nanotube-overgrown carbon paper by electrospraying, forming a highly porous, fractal structure. AC impedance spectroscopy in a symmetric cell configuration revealed a significant reduction of the electrode impedance as compared to similarly prepared electrodes without carbon nanotubes. PMID:23942778

Varga, Aron; Pfohl, Moritz; Brunelli, Nicholas A; Schreier, Marcel; Giapis, Konstantinos P; Haile, Sossina M

2013-08-28

353

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

354

Pseudo-capacitance on exfoliated carbon fiber in sulfuric acid electrolyte  

Microsoft Academic Search

The specific capacitance of exfoliated carbon fibers (ExCF) which were synthesized from pitch-based carbon fibers showed a\\u000a strong dependence with the concentration of sulfuric acid electrolyte and reached 1.4F\\/m2 in 18M H2SO4 solution. Since the capacitance value is quite large compared with the case of conventional activated carbons, faradic reactions\\u000a (charge transfer reactions) are the cause of pseudo-capacitance. ExCF, however,

Y. Soneda; J. Yamashita; M. Kodama; H. Hatori; M. Toyoda; M. Inagaki

2006-01-01

355

Synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotubes and carbon fiber for improved electro-activated polymeric shape-memory nanocomposite  

NASA Astrophysics Data System (ADS)

The present work studies the synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotube (CNT) and carbon fiber on the electrical property and electro-activated recovery behavior of shape memory polymer (SMP) nanocomposites. The combination of CNT and carbon fiber results in improved electrical conductivity in the SMP nanocomposites. Carboxylic acid-functionalized CNTs are grafted onto the carbon fibers and then self-assembled by deposition to significantly enhance the reliability of the bonding between carbon fiber and SMP via van der Waals and covalent crosslink. Furthermore, the self-assembled carboxylic acid-functionalized CNTs and carbon fibers enable the SMP nanocomposites for Joule heating triggered shape recovery.

Lu, Haibao; Min Huang, Wei

2013-06-01

356

Corrosion effects of hydrogen sulfide on coiled tubing and carbon steel in hydrochloric acid  

SciTech Connect

Coiled tubing is commonly used in oilwell drilling and stimulation. It has been reported to be less susceptible to acid attack than carbon steel in acidizing. Corrosion problems are frequently reported from field activities and include corrosion/erosion, galvanic attack, brine/oxygen/acid attack, and HCl/H{sub 2}S attack. In this study, coiled tubing was exposed to inhibited HCl acid in the presence and absence of H{sub 2}S. Four HCl inhibitors and one H{sub 2}S inhibitor were evaluated, and the corrosion rates of coiled tubing, carbon steel (J-55), and carburized steel were compared. Tests were conducted at atmospheric pressure for temperatures less than and equal to 200 F. At temperatures greater than 200 F; tests were conducted at 4,000 psi.

NONE

1997-09-01

357

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. Through laboratory and modeling efforts, 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. Our modeling efforts in the first year show that the idea is feasible, but requires more sophisticated analysis of fluid flow at high pressure in deep sea sediments. 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. Our experimental results from the first year of work have shown that the kinetics are likely to be fast enough to create dissolution which will affect permeability. However, additional experiments are needed at high pressures, which will be a focus for years 2 and 3. 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. Finally, we are in the beginning stages of 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.

Daniel P. Schrag

2005-12-01

358

Microwave-assisted acid digestion of alumina-supported carbon nanotubes  

Microsoft Academic Search

Microwave-assisted acid digestion was assessed for the purification of carbon nanotubes (CNTs), synthesised in a fluidised-bed by chemical vapour deposition (CVD) on alumina-supported catalysts. The effects of (i) digestion time (10, 20 or 30min), (ii) temperature (120, 180 or 230C) and (iii) acid type (HNO3, 12.8mol\\/L or H2SO4, 4.4mol\\/L) were investigated. Thermogravimetric analysis (TGA) results show that CNT purity increases

Jun Liu; Andrew T. Harris

2008-01-01

359

Effects of changes in the major carbon source on the fatty acids of Euglena gracilis  

Microsoft Academic Search

Euglena gracilis was cultured under both heterotrophic and phototrophic growth conditions using ethanol, glucose or CO2 as the major carbon source. Total fatty acid analyses indicated that ethanol produced more highly unsaturated acids than\\u000a did glucose under both growth conditions. Growth in the light on CO2 yielded a very high content of 18?3, 16?3 and 16?4 (33%), compared to ethanol

Ronald C. Reitz; Gary S. Moore

1972-01-01

360

Synthesis of calcium carbonate polymorphs in the presence of polyacrylic acid  

Microsoft Academic Search

Calcium carbonate precipitates are prepared from a solution of CaCl2 and K2CO3 in the presence of polyacrilic acid. The effect of polyacrilic acid incorporation in the [2580C] temperature range on crystal morphologies and CaCO3 precipitated polymorph concentrations are investigated using scanning electron microscopy and X-ray diffraction quantitative microstructural and phase analysis. Large changes in morphology and phase proportions are observed

S. Ouhenia; D. Chateigner; M. A. Belkhir; E. Guilmeau; C. Krauss

2008-01-01

361

Production of activated carbons from a washington lignite using phosphoric acid activation  

Microsoft Academic Search

Chemical activation of a Washington state lignite was studied using heat-treatment temperatures (HTT) between 250 and 650 C. Thermal blanks were generated under similar conditions for comparison. Changes in chemical composition of both the thermal and acid-treated carbons were followed by elemental analysis and FTIR spectroscopy. With increasing HTT, acid-treatment promotes a more extensive loss of hydrogen. Fourier-transform infrared spectra

C. Toles; S. Rimmer; J. C. Hower

1996-01-01

362

Catalytic wet air oxidation of butyric acid solutions using carbon-supported iridium catalysts  

Microsoft Academic Search

Aqueous solutions of butyric acid were treated by catalytic wet air oxidation using carbon-supported iridium catalysts in a stirred reactor. Under the operating conditions of 6.9bar of oxygen partial pressure and 200C of temperature, conversions up to 52.9% after 2h were obtained depending on the type of catalyst used. The effects of butyric acid initial concentration, loading of catalyst, oxygen

H. T Gomes; J. L Figueiredo; J. L Faria

2002-01-01

363

Covalent sidewall functionalization of single-walled carbon nanotubes by amino acids  

Microsoft Academic Search

Single-walled carbon nanotubes (SWNTs) with amino acids covalently attached to their side walls, viz., nanotube-aminoacids, have been prepared starting from colloidal solutions of fluorinated SWNTs (F-SWNTs) and amino acids\\u000a in o-dichlorobenzene and heating at 80150 C in the presence of pyridine. The syntheses were carried out with the F-SWNTs of\\u000a approximately 2: 1 (C: F) stoichiometry and several natural ?-aino

M. X. Pulikkathara; V. N. Khabashesku

2008-01-01

364

Adsorption of benzoic acid onto high specific area activated carbon cloth  

Microsoft Academic Search

The adsorption of benzoic acid from aqueous solution onto high area carbon cloth at different pH values has been studied. Over a period of 125 min the adsorption process was found to follow a first-order kinetics and the rate constants were determined for the adsorption of benzoic acid at pH 2.0, 3.7, 5.3, 9.1, and 11.0. The extents of adsorption

Erol Ayranci; Numan Hoda; Edip Bayram

2005-01-01

365

Efficient optical resolution of amino acid by alanine racemaze chiral analogue supported on mesoporous carbon  

NASA Astrophysics Data System (ADS)

Optically pure D-amino acids are industrially important chiral building blocks for the synthesis of pharmaceuticals, food ingredients, and drug intermediates. Chemoenzymatic dynamic kinetic-resolution processes have recently been developed for deracemization of amino acids. S-ARCA would be a good candidate for the selective adsorption of D amino acid through the imine formation reaction. The organic phase containing S-ARCA adsorbent, TPPC or Ionic Liquid (as a phase transfer catalyst) in MC were coated on the surfaces of mesoporous carbon C-SBA-15(CMK). The aqueous solution of racemic D/L-amino acid and NaOH were added to the carbon support coated with ARCA. The D/L ratios on ARCA and in solution were determined with increasing reaction time. S-ARCA has a unique property for the selective adsorption of D- amino acid (up to 90% selcetivity) in the racemic mixture. The fixed bed reactor containing ARCA/carbon support was also adopted successfully for the selective separation of amino acid.

Jang, D.; Kim, K.; Park, D.; Kim, G.

2012-09-01

366

Effect of acidic treatment on metal adsorptions of pitch-based activated carbon fibers.  

PubMed

In this work, the pitch-based activated carbon fibers (ACFs) were prepared by nitric acid to investigate the multi-metal adsorption in interfacial and textural points of view. N2/77 K adsorption isotherm characteristics, including the specific surface area and micropore volume, were studied by BET specific surface area and t-plot methods, respectively. As a result, the specific surface area of the almost neutral ACFs in nature significantly decreased with nitric acid treatment, probably due to the widening of micropores. However the total acidity, including the carboxyl groups, on carbon surfaces was extremely induced during the acidic surface treatment. From the adsorptions of Cu2+ and Ni2+, it was revealed that the adsorption capacity of metal ions was mainly influenced by the weakly acidic functional groups such as lactones on the carbon surfaces at pH < pI (isoelectric point), and by the strongly acidic functional groups such as carboxyl groups at pH > pI. PMID:15158420

Park, Soo-Jin; Shin, Jun-Sik; Shim, Jae-Woon; Ryu, Seung-Kon

2004-07-01

367

Thiomorpholin-4-ylmethyl-phosphonic acid and morpholin-4-methyl-phosphonic acid as corrosion inhibitors for carbon steel in natural seawater  

Microsoft Academic Search

Electrochemical techniques have been used for investigating the inhibition of carbon steel by thiomorpholin-4-ylmethyl-phosphonic acid (TMPA) and morpholin-4-methyl-phosphonic acid (MPA) in natural seawater. The free corrosion potential was observed to the shift in noble direction which indicated that the phosphonic acids tested inhibit the corrosion of carbon steel in seawater. Potentiodynamic polarization curve shows clearly the fact that the addition

H. Amar; T. Braisaz; D. Villemin; B. Moreau

2008-01-01

368

Simple quantification of surface carboxylic acids on chemically oxidized multi-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The surface of multi-walled carbon nanotube (MWCNT) was chemically oxidized using nitric acid and sulfuric-nitric acid mixtures. Thermogravimetric analysis, transmission electron microscopy and infrared spectroscopy revealed that the use of acid mixtures led to higher degree of oxidation. More quantitative identification of surface carboxylic acids was carried out using X-ray photoelectron spectroscopy (XPS) and acid-base titration. However, these techniques are costly and require very long analysis times to promptly respond to the extent of the reaction. We propose a much simpler method using pH measurements and pre-determined pKa value in order to estimate the concentration of carboxylic acids on the oxidized MWCNT surfaces. The results from this technique were consistent with those obtained from XPS and titration, and it is expected that this simple quantification method can provide a cheap and fast way to monitor and control the oxidation reaction of MWCNT.

Gong, Hyejin; Kim, Seong-Taek; Lee, Jong Doo; Yim, Sanggyu

2013-02-01

369

Particulate, carbon monoxide, and acid emission factors for residential wood burn stoves  

SciTech Connect

Emissions from residential wood burning stoves are of increasing concern in many areas. This concern is due to the magnitude of the emissions and the toxic and chemical characteristics of the pollutants. Recent testing of standard and new technology woodstoves has provided data for developing a family of particulate and carbon monoxide emission factor curves. This testing has also provided data illustrating the acidity of woodstove emissions. The particulate and carbon monoxide curves relate the actual stove emissions to the stove size and operating parameters of burn rate, fuel loading, and fuel moisture. Curves relating stove types to the acidity of emissions have also been constructed. Test data show actual emissions vary from 3 to 50 grams per kilogram for particles and from 50 to 300 grams per kilogram for carbon monoxide. Since woodstove emissions are the largest single category of particulate emissions in many area, it is essential that these emissions be quantified specifically for geographic regions, allowing meaningful impact analysis modeling to be accomplished. Emission factors for particles and carbon monoxide are presented from several stove sizes and burn rates. The acidic nature of woodstove emissions has been clearly demonstrated. Tests indicate woodstove flue gas condensate solutions to be predominantly in the 2.8 to 4.2 pH range. Condensate solutions from conventional woodstoves exhibited the characteristic buffering capacity of carboxylic acids when titrations were performed with a strong base. The environmental impact of buffered acidic woodstove emissions is not currently well understood; however, it is possible with the data presented here to make semi-quantitative estimates of acid emission from particulate and carbon monoxide emission factors and wood use inventories.

Burnet, P.G.; Edmisten, N.G.; Tiegs, P.E.; Houck, J.E.; Yoder, R.A.

1986-09-01

370

Solids, Liquids, and Gases  

NSDL National Science Digital Library

Objective: Students will be introduced to solids, liquids, and gases. Students will identify key characteristics of the three states of matter. Everything is made of matter. Matter is made of atoms. Matter makes up solids, liquids, and gases. What are some similarities and differences between solids, liquids, and gases? Follow the link below to find out. Characteristics of the States of Matter The previous website gave some general characteristics for solids, liquids, and gases. Now ...

Rohlfing, Mrs.

2010-10-22

371

A selective voltammetric method for uric acid detection at Nafion(R)-coated carbon paste electrodes.  

PubMed

A square-wave voltammetric method together with Nafion(R)-coated carbon paste electrodes were used for the selective determination of uric acid in the presence of a high concentration of ascorbic acid. Since the oxidation potential of uric acid is about 200 mV more positive than that of ascorbic acid at the Nafion(R)-coated carbon paste electrode, the selectivity can be greatly improved simply by applying an electrolysis potential of +0.4 V vs. Ag/AgCl where only ascorbic acid is oxidised. The acceptable tolerance of ascorbic acid concentration for the determination of uric acid is as high as 1.5 mM. With 30 s of electrolysis time, a linear calibration curve is obtained over the 0-50 muM range in 0.05 M citrate buffer solution, pH 4.0, with slope (muA/muM) and correlation coefficient of 0.34 and 0.9984, respectively. The detection limit (3sigma) is 0.25 muM. The practical analytical utility is illustrated by selective measurements of uric acid in human urine without any preliminary treatment. PMID:18967265

Zen, J M; Hsu, C T

1998-08-01

372

Physicochemical properties of carbons prepared from pecan shell by phosphoric acid activation.  

PubMed

Activated carbons were prepared from pecan shell by phosphoric acid activation. The pore structure and acidic surface groups of these carbons were characterized by nitrogen adsorption, Boehm titration and transmittance Fourier infrared spectroscopy (FTIR) techniques. The characterization results demonstrated that the development of pore structure was apparent at temperatures 250 degrees C, and reached 1130m(2)/g and 0.34cm(3)/g, respectively, at 500 degrees C. Impregnation ratio and soaking time at activation temperature also affected the pore development and pore size distribution of final carbon products. At an impregnation ratio of 1.5, activated carbon with BET surface area and micropore volume as high as 861m(2)/g and 0.289cm(3)/g was obtained at 400 degrees C. Microporous activated carbons were obtained in this study. Low impregnation ratio (less than 1.5) and activation temperature (less than 300 degrees C) are favorable to the formation of acidic surface functional groups, which consist of temperature-sensitive (unstable at high temperature) and temperature-insensitive (stable at high temperature) two parts. The disappearance of temperature-sensitive groups was significant at temperature 300 degrees C; while the temperature-insensitive groups are stable even at 500 degrees C. FTIR results showed that the temperature-insensitive part was mostly phosphorus-containing groups as well as some carbonyl-containing groups, while carbonyl-containing groups were the main contributor of temperature-sensitive part. PMID:16973352

Guo, Yanping; Rockstraw, David A

2006-09-14

373

A study of sulfuric and Acetic acid effect on vertically aligned carbon Nanofibers for bio\\/chemical sensors development  

Microsoft Academic Search

Materials behave differently with different chemicals. Carbon Nanofibers are no exclusion for this. During the fabrication process of carbon nanofibers, the chips are treated with a lot of chemicals including a variety of acids. Thus with a better understanding about the fibers behavior in the presence of commonly used acids will give us edge in the development of the well

Siva Naga Sandeep Chalamalasetty; Uchechukwu C. Wejinya; Zhuxin Dong; Meyya Meyyappan

2011-01-01

374

Analysis of the corrosion of carbon steels in simulated salt repository brines and acid chloride solutions at high temperatures  

Microsoft Academic Search

An analysis of literature data on the corrosion of carbon steels in anoxic brines and acid chloride solutions was performed, and the results were used to assess the expected life of high-level nuclear waste package containers in a salt repository environment. The corrosion rate of carbon steels in moderately acidic aqueous chloride environments obeys an Arrhenius dependence on temperature and

D. R. Diercks; T. F. Kassner

1988-01-01

375

Acid rain damage to carbonate stone: a quantitative assessment based on the aqueous geochemistry of rainfall runoff from stone  

USGS Publications Warehouse

An onsite experimental procedure was used to identify and quantify acid rain damage to carbonate stone, based on the change in rain runoff chemical composition. Onsite data obtained during the summer and fall of 1984 at three locations in the northeastern United States indicate that carbonate stone surface recession is related to acid deposition. -from Author

Reddy, M. M.

1988-01-01

376

Large scale microwave-accelerated esterification of carboxylic acids with dimethyl carbonate  

Microsoft Academic Search

An environmentally friendly process for the esterification of carboxylic acids with dimethyl carbonate can be accelerated by employing a combined strategy: using 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) as the catalyst (chemical means) and microwave as the energy source (physical means). This approach provides synthetic advantages, niches, and upscalability.

Wen-Chung Shieh; Steven Dell; Oljan Repi?

2002-01-01

377

EFFECT OF ACID TREATMENT ON DISSOLVED ORGANIC CARBON RETENTION BY A SPODIC HORIZON  

EPA Science Inventory

Processes involving the movement of organic substances in forest soils are not well understood. This study was conducted to examine the role of acidic inputs on dissolved organic carbon (DOC) mobility, processes affecting the retention of DOV by a B horizon, and SO2-4 adsorption....

378

Pervaporation of acetic acid\\/water mixtures through carbon molecular sieve-filled PDMS membranes  

Microsoft Academic Search

The pervaporation process for acetic\\/water has been investigated with carbon molecular sieve (CMS)-filled polydimethylsiloxane (PDMS) membranes. The effects of feed temperature, feed acetic acid concentration and CMS content on the performance of the membranes have been studied. It is found that the addition of CMS can improve pervaporation behavior of PDMS membranes to some extent and greatly increases the strength

Lei Li; Zeyi Xiao; Zhibing Zhang; Shujuan Tan

2004-01-01

379

Does the Acid HydrolysisIncubation Method Measure Meaningful Soil Organic Carbon Pools?  

Microsoft Academic Search

The literature was reviewed and analyzed to determine the fea- sibility of using a combination of acid hydrolysis and CO2-C release during long-term incubation to determine soil organic carbon (SOC) pool sizes and mean residence times (MRTs). Analysis of 1100 data points showed the SOC remaining after hydrolysis with 6 M HCl ranged from 30 to 80% of the total

Eldor A. Paul; Sherri J. Morris; Richard T. Conant; Alain F. Plante

2006-01-01

380

Improvement of biodegradability of ethylenediaminetetraacetic acid in biological activated carbon treatment by chemical preoxidation  

Microsoft Academic Search

This paper deals with the chemical oxidation to enhance the biodegradability of ethylenediaminetetraacetic acid (EDTA), which is regarded as one of the non-biodegradable substances, as a pretreatment for biological activated carbon (BAC) treatment. The use of EDTA is indispensable in many industries. However, when it is contained in wastewater, difficulty arises concerning treatment because of its stable chemical structure. Wastewaters

K. Mochidzuki; Y. Takeuchi

1999-01-01

381

Numbers of bacteria recovered from broiler carcasses and chiller water treated with hypochlorous and carbonic acids  

Technology Transfer Automated Retrieval System (TEKTRAN)

A study was conducted to determine the effects of treating poultry chiller water with a mixture of hypochlorous and carbonic acids. Broiler carcasses and chiller water were obtained from a commercial processing facility which had recently installed a TOMCO Pathogen Management SystemJ to recycle wat...

382

Preparation, characterization and Methylene Blue adsorption of phosphoric acid activated carbons from globe artichoke leaves  

Microsoft Academic Search

Activated carbons were prepared by the pyrolysis of artichoke leaves impregnated with phosphoric acid at 500C for different impregnation ratios: 100, 200, 300wt.%. Materials were characterized for their surface chemistry by elemental analysis, Boehm titrations, point of zero charge measurements, infrared spectroscopy, as well as for their porous and morphological structure by Scanning Electron Microscopy and nitrogen adsorption at 77K.

M. Benadjemia; L. Millire; L. Reinert; N. Benderdouche; L. Duclaux

2011-01-01

383

Anchoring metal nanoparticles on hydrofluoric acid treated multiwalled carbon nanotubes as stable electrocatalysts  

Microsoft Academic Search

We attempted the treatment of multiwalled carbon nanotubes (MWCNTs) in hydrofluoric acid (HF) aqueous solution for depositing Pt nanoparticles as catalysts for methanol oxidation for the first time. The preliminary results revealed that the Pt nanoparticles could be well dispersed on HF treated MWCNTs and gave enhanced activity and stability for methanol oxidation. As demonstrated in this study, the Pt

Yongliang Li; Feng Ping Hu; Xin Wang; Pei Kang Shen

2008-01-01

384

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

385

ELECTROCHEMICAL STUDIES ON THE CORROSION OF CARBON STEEL IN OXALIC ACID CLEANING SOLUTIONS  

Microsoft Academic Search

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,

B Wiersma; J John Mickalonis

2007-01-01

386

Acetic Acid Digestion of High-Carbonate Substrates: An Aid to Sorting Aquatic Invertebrate Samples  

Microsoft Academic Search

Soaking high-carbonate sediment samples in 5% acetic acid reduces initial sample volumes; sorting times per unit of original volume and per organism also declined significantly compared with untreated samples. This procedure speeds the sorting of invertebrate samples, especially when similar specific gravities of organisms and substrates render useless the techniques of flotation and elutriation.

Amy Odell Daraghy; Roxanne Conrow; William F. Loftus

1988-01-01

387

Elution of zinc in dust discharged from electric arc furnace in carbonic acid solution  

Microsoft Academic Search

The dust discharged from an electric arc furnace (EAF) is a valuable resource of zinc. As a fundamental study of extraction of zinc, iron and chlorine in the EAF dust, the elution behavior of them in carbonic acid solution was studied. The influence of the weight of the EAF dust on the elution behavior was examined in this study. Experiment

S Yokoyama; T Sasaki; J Sasano; M Izaki

2012-01-01

388

[Factors enhancing the stability of ascorbic acid in alcohol-free carbonated drinks].  

PubMed

Factors were studied influencing the stability of ascorbic acid (AA) in carbonated drink "Legenda". It has been established that beet-tea pigment and its mixture with polyvinylpyrrolidone produce a high stabilizing effect on AA due to formation of stable complexes with AA, which was supported by the data of spectrophotometry. PMID:2346017

Golubkina, N A; Prudnik, O V; Grum-Grzhima?lo, M A; Guzikova, I A

389

Biodegradable poly-lactic acid package for the storage of carbonic maceration wine  

Microsoft Academic Search

The influence of the potential environmentally friendly poly-lactic acid (PLA) on the quality loss of carbonic maceration wine is investigated in this work. In particular, PLA bottles were compared with polyethylene terephthalate (PET) and glass ones. Classical oenological parameters, volatile fraction and sensory attributes were monitored over 4 months assessing the chemical and sensory changes related to oxidation and flavor

S. Pati; A. Mentana; E. La Notte; M. A. Del Nobile

2010-01-01

390

Effect of ZnSO4 upon gastric acid secretion and carbonic anhydrase.  

PubMed

Starting from the multiple role zinc holds in the enzymatic processes of the body and from some positive data concerning treatment with zinc sulphate in gastric ulcer, we have studied the effect of ZnSO4 on gastric acid secretion in duodenal ulcer patients, as well as that on purified and gastric mucosa carbonic anhydrase. Gastric secretory testing showed that zinc sulphate administered in doses of 60 ml/day (1% solution) for 10 days reduced basal acid secretion in duodenal ulcer patients by 57.7%. In vitro, concentrations of ZnSO4 ranging between 10(-6) and 10(-2)M, inhibit purified carbonic anhydrase activity in a dose-dependent manner, reaching maximum effect at 10(-2)M, when carbonic anhydrase activity dropped from 2060 +/- 65 IU to 660 +/- 85 IU. A similar dose-dependent inhibition was found with gastric mucosa carbonic anhydrase activity, where ZnSO4 at 10(-2)M reduces enzyme activity from its basal value of 1.58 +/- 0.36 EU/mg to 0.88 +/- 0.21 EU/mg. Besides this effect, zinc sulphate antagonized in vitro the activation of both purified and gastric mucosa carbonic anhydrase by histamine. In conclusion, the mechanism of antisecretory effect of ZnSO4 might well be the inhibition of the carbonic anhydrase in the gastric mucosa. PMID:4077313

Puscas, I; Sturzu, L; Bzs, G

1985-11-01

391

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

392

Vertically aligned carbon nanofiber electrode arrays for nucleic acid detection  

NASA Astrophysics Data System (ADS)

We present electrochemical detection of DNA targets that corresponds to Escherichia coli O157:H7 16S rRNA gene using a nanoelectrode array consisting of vertically aligned carbon nanofiber (VACNF) electrodes. Parylene C is used as gap filling 'matrix' material to avoid high temperature processing in electrode construction. This easy to deposit film of several micron heights provides a conformal coating between the high aspect ratio VACNFs with negligible pin-holes. The low background currents show the potential of this approach for ultra-sensitive detection. Consistent and reproducible electrochemical-signals are achieved using a simple electrode preparation. This simple, reliable and low-cost approach is a forward step in developing practical sensors for applications like pathogen detection, early cancer diagnosis and environmental monitoring.

Arumugam, Prabhu U.; Yu, Edmond; Riviere, Roger; Meyyappan, M.

2010-10-01

393

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

394

Separation of polar gases from nonpolar gases  

DOEpatents

The separation of polar gases from nonpolar gases may be effected by passing a mixture of 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 porous support is pretreated prior to casting of the mixture thereon by contact with a polyhydric alcohol whereby the pores of the support are altered, thus adding to the increased permeability of the polar gas.

Kulprathipanja, S.

1986-08-19

395

Norepinephrine-modified glassy carbon electrode for the simultaneous determination of ascorbic acid and uric acid  

Microsoft Academic Search

The oxidation of norepinephrine (NE) on a preactivated glassy carbon electrode leads to the formation of a deposited layer of about 4.210?10molcm?2 at the surface of the electrode. The electron transfer rate constant, ks, and charge transfer coefficient, ?, for electron transfer between the electrode and immobilized NE film were calculated as 44s?1 and 0.46, respectively. The NE-modified glassy carbon

H. R. Zare; F. Memarzadeh; M. Mazloum Ardakani; M. Namazian; S. M. Golabi

2005-01-01

396

Variation in the Carbon Isotope Composition of a Plant with Crassulacean Acid Metabolism  

PubMed Central

The content of 13C varies in plants with Crassulacean acid metabolism. Differences up to 3.5 in the 13C/12C ratios were observed between leaves of different age in the same plant of Bryophyllum daigremontianum. Soluble and insoluble carbon in the same leaf differed up to 8, the largest difference occurring in the leaves with the highest Crassulacean acid metabolism activity. Models to account for the isotope discrimination by C3, C4, and Crassulacean acid metabolism plants are proposed.

Lerman, J. C.; Deleens, Eliane; Nato, Aime; Moyse, Alexis

1974-01-01

397

Incorporation of C14 From Carbon Dioxide into Sugar Phosphates, Carboxylic Acids, and Amino Acids by Clostridium thermoaceticum  

PubMed Central

Ljungdahl, Lars (Western Reserve University, Cleveland, Ohio), and Harland G. Wood. Incorporation of C14 from carbon dioxide into sugar phosphates, carboxylic acids, and amino acids by Clostridium thermoaceticum. J. Bacteriol. 89:10551064. 1965.The mechanism of synthesis of acetate from carbon dioxide by Clostridium thermoaceticum was investigated by incubating cells with glucose or xylose in the presence of C14O2. Sugar phosphates, amino acids, and carboxylic acids were isolated and the specific radioactivities were determined; the distributions of C14 were also determined in some of the compounds. Only fructose-1,6-diphosphate, formate, and lactate had higher specific activities than the acetate. The specific activities and distribution of C14 in the fructose-6-phosphate and ribose-5-phosphate were such that we conclude that the synthesis of acetate does not occur via a pathway involving the sugar phosphates as direct intermediates. Likewise, it is shown that pathways including lactate, aspartate, serine, glycine, malate, and succinate are not of importance in the synthesis of acetate from CO2. The methyl group of free methionine was unlabeled and is not a precursor of the methyl group of acetate.

Ljungdahl, Lars; Wood, Harland G.

1965-01-01

398

Controlled exposures of volunteers to respirable carbon and sulfuric acid aerosols  

SciTech Connect

Respirable carbon or fly ash particles are suspected to increase the respiratory toxicity of coexisting acidic air pollutants, by concentrating acid on their surfaces and so delivering it efficiently to the lower respiratory tract. To investigate this issue, the authors exposed 15 healthy and 15 asthmatic volunteers in a controlled-environment chamber to four test atmospheres: (1) clean air; (2) 0.5-{mu}m H{sub 2}SO{sub 4} aerosol at {approx}100 {mu}g/m{sup 3}, generated from water solution; (3) 0.5-{mu}m carbon aerosol at {approx}250 {mu}g/m{sup 3}, generated from highly pure carbon black with specific surface area comparable to ambient pollution particles; and (4) carbon as in (3) plus {approx}100 {mu}g/m{sup 3} of ultrafine H{sub 2}SO{sub 4} aerosol generated from fuming sulfuric acid. Electron microscopy showed that nearly all acid in (4) became attached to carbon particle surfaces, and that most particles remained in the sub-{mu}m size range. Exposures were performed double-blind, 1 week apart. They lasted 1 hr each, with alternate 10-min periods of heavy exercise (ventilation {approx}50 L/min) and rest. Subjects gargled citrus juice before exposure to suppress airway ammonia. Lung function and symptoms were measured pre-exposure, after initial exercise, and at end-exposure. Bronchial reactivity to methacholine was measured after exposure. Statistical analyses tested for effects of H{sub 2}SO{sub 4} or carbon, separate or interactive, on health measures.

Anderson, K.R.; Avol, E.L.; Edwards, S.A.; Shamoo, D.A.; Ruchuan Peng; Linn, W.S.; Hackney, J.D. (Univ. of Southern California, Downey (United States))

1992-06-01

399

Matrix isolation studies of carbonic acid--the vapor phase above the ?-polymorph.  

PubMed

Twenty years ago two different polymorphs of carbonic acid, ?- and ?-H2CO3, were isolated as thin, crystalline films. They were characterized by infrared and, of late, by Raman spectroscopy. Determination of the crystal structure of these two polymorphs, using cryopowder and thin film X-ray diffraction techniques, has failed so far. Recently, we succeeded in sublimating ?-H2CO3 and trapping the vapor phase in a noble gas matrix, which was analyzed by infrared spectroscopy. In the same way we have now investigated the ?-polymorph. Unlike ?-H2CO3, ?-H2CO3 was regarded to decompose upon sublimation. Still, we have succeeded in isolation of undecomposed carbonic acid in the matrix and recondensation after removal of the matrix here. This possibility of sublimation and recondensation cycles of ?-H2CO3 adds a new aspect to the chemistry of carbonic acid in astrophysical environments, especially because there is a direct way of ?-H2CO3 formation in space, but none for ?-H2CO3. Assignments of the FTIR spectra of the isolated molecules unambiguously reveal two different carbonic acid monomer conformers (C(2v) and C(s)). In contrast to the earlier study on ?-H2CO3, we do not find evidence for centrosymmetric (C(2h)) carbonic acid dimers here. This suggests that two monomers are entropically favored at the sublimation temperature of 250 K for ?-H2CO3, whereas they are not at the sublimation temperature of 210 K for ?-H2CO3. PMID:23631554

Bernard, Jrgen; Huber, Roland G; Liedl, Klaus R; Grothe, Hinrich; Loerting, Thomas

2013-05-14

400

Pd-loaded carbon felt as the cathode for selective dechlorination of 2,4-dichlorophenoxyacetic acid in aqueous solution  

SciTech Connect

Electrocatalytic reductive dehalogenation of 2,4-dichlorophenoxyacetic acid (2,4-D) to phenoxyacetic acid in aqueous solution containing MeOH, trifluoroacetic acid, and tetraalkylammonium salt was studied. A Teflon-made two-compartment flow-through cell with a permeable carbon felt cathode and a platinum foil anode was employed. Several noble metals were tested as electrocatalysts. Palladium-loaded carbon felt was found to be the most suitable significantly enhanced its electrocatalytic activity toward 2,4-D dechlorination. The reaction was hypothesized to proceed at carbon-palladium interface areas through 4-chlorine cleavage to form 2-chlorophenoxyacetic acid as the main reaction intermediate.

Tsyganok, A.I.; Yamanaka, Ichiro; Otsuka, Kiyoshi [Tokyo Inst. of Tech. (Japan). Dept. of Chemical Engineering

1998-11-01

401

The healing effect of stearic acid applied on amorphous carbon film with dispersed nanodiamonds  

NASA Astrophysics Data System (ADS)

Diamond-like carbon (DLC) films have been shown to improve the friction and wear properties of applications with severe loads. Hydrogenated amorphous carbon films (a-C:H), a type of DLC film, were coated onto 440C stainless steel disk surfaces. The plasma enhanced chemical vapour deposition method was used as a coating process, and nanodiamond (ND) particles were dispersed into the film during the deposition process. Stearic acid was expected to affect the lubricating properties of the film because of its reported effectiveness on diamond surfaces. A lubricated reciprocal sliding friction test with 10,000 cycles confirmed that stearic acid improved the friction and wear properties of the ND dispersed a-C:H film. Furthermore, film wear caused by a sliding test without stearic acid could be healed by sliding with stearic acid as long as the level of critical damage was not reached. Raman spectra for the worn tracks revealed the healing effect of the stearic acid on the film because the spectra for the worn tracks after 10,000 cycles were identical to those of the control film, which was not worn. In contrast, the spectra for the worn tracks or debris showed a broad D band peak and no G peak, which was consistent with disordered amorphous carbon.

Yamazaki, T.; Shoji, K.; Ikeshoji, T.-T.; Suzumura, A.

2012-08-01

402

Patterns of intramolecular carbon isotopic heterogeneity within amino acids of autotrophs and heterotrophs.  

PubMed

A survey of the intramolecular C isotopic composition of a variety of organisms was conducted to investigate the potential of intramolecular isotopic measurements as a tracer of biological or geochemical processes. Based on a consideration of inorganic C sources and enzymatic fractionations, contrasting predictions were made for the relative (13)C enrichments of the alpha-carboxyl carbons fixed by the anapleurotic (beta)-carboxylation pathway during amino acid synthesis by photoautotrophs and heterotrophs. To test the model predictions, the stable C isotopic compositions of the acid hydrolyzable C fraction, the total amino acid alpha-carboxyl C fraction and the alpha-carboxyl C of glutamate from a variety of autotrophic and heterotrophic organisms were compared. The relative (13)C enrichments of carboxyl carbons in the bulk amino acid fraction and in glutamate conformed qualitatively to model predictions. Macroalgal taxa possessed a significantly less enriched carboxyl C fraction than did either C3 or C4 vascular plants, indicating the presence of a different beta-carboxylation pathway operating in these organisms. In most multicellular heterotrophs, the isotopic composition of the amino acid carboxyl carbons closely resembled that of their food sources. Amino acids are apparently assimilated into tissue proteins directly from their diets without significant metabolic modification. However, shifts in the isotopic composition of the carboxyl C fractions in some organisms were detected that were consistent with the occurrence of significant resynthesis of amino acids from non-amino acid precursors. Comparison of plant leaves and roots provided evidence of environmentally controlled assimilate partitioning. Intramolecular isotopic measurements of biological molecules provide unique insights into the origins and transformations of bio-molecules. PMID:14986094

Savidge, William B; Blair, Neal E

2004-02-24

403

Cardiopulmonary responses to intravenous infusion of soluble and relatively insoluble gases  

Microsoft Academic Search

Background: Carbon dioxide is the current gas of choice for pneumoperitoneum, but hemodynamic and acidbase effects secondary to its\\u000a systemic absorption have been reported. Various studies have suggested inert gases as alternatives.\\u000a \\u000a \\u000a \\u000a \\u000a \\u000a Methods: We studied the cardiopulmonary responses to intravenous infusion of carbon dioxide, nitrous oxide, argon, helium, and nitrogen\\u000a in anesthetized swine. The gas was infused into the femoral

M. W. Roberts; K. A. Mathiesen; H. S. Ho; B. M. Wolfe

1997-01-01

404

Fatty Acids and Stable Carbon Isotopes of a Sulfate-Reducing Bacterium: Implications for Carbon Cycling in Organic-Rich Marine Sediments  

Microsoft Academic Search

Sulfate-reducing bacteria have characteristic lipid biomarkers, which help delineate carbon cycling pathways under sulfate-reducing conditions. This is especially important for marine sediments because of the predominance of sulfate reduction in such environments. Little research has been done to determine carbon isotope fractionations associated with lipid biomarkers of known sulfate-reducing bacteria. We examined the fatty acid compositions and their carbon isotope

J. McBeth; B. Giles; E. Ye; Y. Li; C. L. Zhang; J. D. Wall; Y. Huang; J. Horita; D. R. Cole

2001-01-01

405

A comparative investigation on adsorption performances of mesoporous activated carbon prepared from waste rubber tire and activated carbon for a hazardous azo dyeAcid Blue 113  

Microsoft Academic Search

A mesoporous carbon developed from waste tire rubber, characterized by chemical analysis, FTIR, and SEM studies, was used as an adsorbent for the removal and recovery of a hazardous azo dye, Acid Blue 113. Surface area, porosity, and density were determined. The adsorption of the dye over the prepared adsorbent and a commercial activated carbon was achieved under different pH,

V. K. Gupta; Bina Gupta; Arshi Rastogi; Shilpi Agarwal; Arunima Nayak

2011-01-01

406

Trade-off in emissions of acid gas pollutants and of carbon dioxide in fossil fuel power plants with carbon capture  

Microsoft Academic Search

This paper investigates the impact of capture of carbon dioxide (CO2) from fossil fuel power plants on the emissions of nitrogen oxides (NOX) and sulphur oxides (SOX), which are acid gas pollutants. This was done by estimating the emissions of these chemical compounds from natural gas combined cycle and pulverized coal plants, equipped with post-combustion carbon capture technology for the

Evangelos Tzimas; Arnaud Mercier; Calin-Cristian Cormos; Stathis D. Peteves

2007-01-01

407

The formation of amino acid precursors in the reaction of atomic carbon with water and ammonia at 77 K  

NASA Astrophysics Data System (ADS)

When atomic carbon is condensed on a surface at 77 K containing ammonia and water, glycine, N-methylglycine, alanine, ?-alanine, aspartic acid and serine are generated. It is postulated that these reactions may mimic those which occur when an extraterrestrial carbon atom condenses on a frozen surface coated with water and ammonia and may provide a route to extraterrestrial amino acids. Experiments designed to elucidate the mechanisms of amino acid formation under these conditions have been carried out.

McPherson, Daniel W.; Rahman, Kazi; Martinez, Iris; Shevlin, Philip B.

1987-09-01

408

Electrochemical determination of ferulic acid in Chinese traditional medicine Xiao Yao Pills at electrode modified with carbon nanotube  

Microsoft Academic Search

The electrochemical behaviors of ferulic acid were investigated at the glassy carbon electrode modified with multi-walled\\u000a carbon nanotube. In pH 5.5, 0.1 mol l?1 HAc-NaAc buffer solution, ferulic acid exhibited a pair of stable and sensitive redox signals at the modified electrode.\\u000a The reaction mechanism was explored. Through the cyclic voltammetry, trace amount of ferulic acid was detected quantitatively.\\u000a In

Yan-Yan Yu; Qing-Sheng Wu; Xiao-Gang Wang; Ya-Ping Ding

2009-01-01

409

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.

410

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, 1.70.5 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

411

Reaction rate vs. transport limited dissolution during carbonate acidizing: Application of network model  

SciTech Connect

Coreflood experiments have been performed and a two dimensional network model has been developed to study the flow, dissolution, and permeability increase in carbonates during acid stimulation treatments. The goal is to be able to predict the behaviour of the random flow channels, called wormholes, that form in the rock as a result of acid attack. Understanding this channeling phenomenon is essential in predicting acid penetration distances and the resulting injectivity or productivity increases during matrix acidizing, or in understanding acid leakoff behaviour during fracture acidizing. Until now, relatively little has been known about the wormholing phenomenon because of the stochastic nature of channel formation and the inherent difficulty in modelling the random behaviour. Model predictions and experimental coreflood results are compared for linear systems. The model predicts wormholing and the effects of acidizing parameters such as fluid velocity, mineral dissolution rate, and rock properties on channel structure and the corresponding rate of channel propagation. Experimental data and model prediction support the conclusion that wormholing is necessary for matrix treatment effectiveness, but does not occur for the extremes of high and low values of the Damkohler number for flow and reaction, which controls the process. The model thus accounts for the ineffectiveness of aqueous hydrochloric acid for matrix treatments in limestone due to rapid acid spending, and for the possible ineffectiveness of treatments in dolomite due to mineral dissolution rates that are too slow to promote channel formation.

Hoefner, M.L.; Fogler, H.S.

1986-01-01

412

Hepatoprotective effect of Matrine salvianolic acid B salt on Carbon Tetrachloride-Induced Hepatic Fibrosis.  

PubMed

The aim of this study was to investigate the hepatoprotective effect of Matrine salvianolic acid B salt on carbon tetrachloride (CCl4)-induced hepatic fibrosis in rats. Salvianolic acid B and Matrine has long been used to treat liver fibrosis. Matrine salvianolic acid B salt is a new compound containing Salvianolic acid B and Matrine. Hepatic fibrosis induced by CCl4 was studied in animal models using Wistar rats. Organ coefficient, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), hexadecenoic acid (HA), laminin (LN), hydroxyproline (Hyp), and glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD) in liver tissues were measured, respectively. Histopathological changes in the livers were studied by hematoxylin-eosin (H&E) staining and Masson Trichrome (MT) examination. The expression of transforming growth factor-?1 (TGF-?1) and ?-smooth muscle actin (?-SMA) was observed by immunohistochemical analysis. A significant reduction in serum levels of AST, ALT, HA, LN and Hyp was observed in the Matrine salvianolic acid B salt treated groups, suggesting that the salt had hepatoprotective effects. The depletion of GSH and SOD, as well as MDA accumulation in liver tissues was suppressed by Matrine salvianolic acid B salt too. The expression of TGF-?1 and ?-SMA measured by immunohistology was significantly reduced by Matrine salvianolic acid B salt in a dose-dependent manner. Matrine salvianolic acid B salt treatment attenuated the necro-inflammation and fibrogenesis induced by CCl4 injection, and thus it is promising as a therapeutic anti-fibrotic agent against hepatic fibrosis. PMID:22559721

Gao, Hong-Ying; Li, Guo-Yu; Lou, Meng-Meng; Li, Xiao-Yu; Wei, Xiu-Yan; Wang, Jin-Hui

2012-05-04

413

Hepatoprotective effect of Matrine salvianolic acid B salt on Carbon Tetrachloride-Induced Hepatic Fibrosis  

PubMed Central

The aim of this study was to investigate the hepatoprotective effect of Matrine salvianolic acid B salt on carbon tetrachloride (CCl4)-induced hepatic fibrosis in rats. Salvianolic acid B and Matrine has long been used to treat liver fibrosis. Matrine salvianolic acid B salt is a new compound containing Salvianolic acid B and Matrine. Hepatic fibrosis induced by CCl4 was studied in animal models using Wistar rats. Organ coefficient, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), hexadecenoic acid (HA), laminin (LN), hydroxyproline (Hyp), and glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD) in liver tissues were measured, respectively. Histopathological changes in the livers were studied by hematoxylin-eosin (H&E) staining and Masson Trichrome (MT) examination. The expression of transforming growth factor-?1 (TGF-?1) and ?-smooth muscle actin (?-SMA) was observed by immunohistochemical analysis. A significant reduction in serum levels of AST, ALT, HA, LN and Hyp was observed in the Matrine salvianolic acid B salt treated groups, suggesting that the salt had hepatoprotective effects. The depletion of GSH and SOD, as well as MDA accumulation in liver tissues was suppressed by Matrine salvianolic acid B salt too. The expression of TGF-?1 and ?-SMA measured by immunohistology was significantly reduced by Matrine salvianolic acid B salt in a dose-dependent manner. Matrine salvianolic acid B salt treatment attenuated the necro-inflammation and fibrogenesis induced by CCl4 injection, and thus it is promising as a therapeutic anti-fibrotic agent against hepatic fibrosis.

2012-01-01

414

Analysis of the stable carbon isotope composition of formic and acetic acids.  

PubMed

Formic and acetic acids are ubiquitous in the environment and in many biological processes. Analysis of the stable carbon isotope composition (?(13)C) of formic and acetic acids is important to understanding their biogeochemical cycles. However, it has been faced with poor accuracy and high detection limits due to their low carbon number, high hydrophilicity, and semi-volatility. Here we developed an analytical technique by needle trap and gas chromatography-isotope ratio mass spectrometry (GC-IRMS). The organic acids in aqueous solution were extracted using a NeedlEx needle through purge-and-trap and were analyzed by GC-IRMS for ?(13)C. The procedures incur no isotope fractionation. Defined as the point at which the mean ?(13)C is statistically the same as the given value and the analytical error starts rising, the method's detection limits are 200 and 100 mg/L for formic and acetic acids, respectively, with an uncertainty of approximately 0.5 in direct extraction and analysis. They were lowered to 1 mg/L with precision of 0.9 after samples were subjected to preconcentration. The method was successfully applied to natural samples as diverse as precipitation, vinegars, ant plasma, and vehicle exhaust, which vary considerably in concentration and matrix of the organic acids. It is applicable to the organic acids in not only aqueous solution but also gaseous phase. PMID:23395975

Lee, Xinqing; Zhang, Like; Huang, Daikuan; An, Ning; Yang, Fang; Jiang, Wei; Fang, Bin

2013-02-08

415

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

SciTech Connect

This paper describes a laboratory experiment on the effects of acidic deposition on carbonate stone erosion. It can serve as the basis for an undergraduate (or pre college) experiment in environmental chemistry. Recent field investigations are described that provide measurements of carbonate stone dissolution and mechanical erosion under weathering conditions that are prevalent in the eastern US. The purpose of the laboratory work is to answer questions concerning the effects of hydrogen ion deposition on stone erosion processes that were difficult to resolve on the basis of field experiments alone.

Baedecker, P.A. (Geological Survey, Reston, VA (United States)); Reddy, M.M. (Geological Survey, Lakewood, CO (United States))

1993-02-01

416

Extraction of palladium from acidic solutions with the use of carbon adsorbents  

SciTech Connect

We studied the sorption of palladium(II) on LKAU-4, LKAU-7, and BAU carbon adsorbents from model hydrochloric acid solutions and the solutions of spent palladium-containing catalysts. It was found that sorbents based on charcoal (BAU) and anthracite (LKAU-4) were characterized by high sorption capacities for palladium. The kinetics of the saturation of carbon adsorbents with palladium(II) ions was studied, and it was found that more than 60% of the initial amount of Pd(II) was recovered in a 1-h contact of an adsorbent with a model solution. This value for the solutions of spent catalysts was higher than 35%.

O.N. Kononova; N.G. Goryaeva; N.B. Dostovalova; S.V. Kachin; A.G. Kholmogorov [Krasnoyarsk State University, Krasnoyarsk (Russian Federation)

2007-08-15

417

75 FR 17331 - Public Hearings for the Mandatory Reporting Rule for Greenhouse Gases  

Federal Register 2010, 2011, 2012, 2013

...Greenhouse Gases: Injection and Geologic Sequestration of Carbon Dioxide...carbon dioxide injection and geologic sequestration. The signed...to the presentations at that time. Written statements and supporting...Carbon Dioxide Injection and Geologic Sequestration, proposed...

2010-04-06

418

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

NASA Astrophysics Data System (ADS)

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 acid, with vegetation emissions being the most likely controlling source. Collection of relatively large quantities (0.3 -3.0 mg) of the organic acids, which was necessary for carbon isotopic measurements, was effectively accomplished by a new method using calcium hydroxide-treated filters with a high-volume sampler. Samples were collected on a regular basis at Mount Lemmon, Arizona (elevation = 9200 feet A.S.L.). Atmospheric concentrations showed a well-defined seasonal pattern, with the lowest concentrations (about 0.2 ppbv) occurring in the middle of the winter, which steadily increased to a maximum of nearly 2 ppbv in the summer. The ^{13}C content (delta ^{13}C) of HCOOH averaged -20.9 +/- 2.5 ^0/_{00 } during the growing season (April-September) and -23.2 +/- 3.5 ^0/_{00} during the non-growing season at Mount Lemmon. Isotopic measurements of formic acid from several other locations included two west coast marine sites ( delta ^{13} C range of -19.1 to -24.6 ^0/_{00} ), three Colorado Rocky Mountain samples averaging -23.2 +/- 1.0 ^0/_{00}, two from the prairie of North Dakota (-23.5 +/- 1.0 ^0/ _{00}) and three samples collected in the urban Tucson, Arizona area (- 20.8 +/- 3.4 ^0 /_{00}). Source measurements included HCOOH emissions from two species of formicine ants (-18.8 +/- 1.7 ^0/_ {00}), and HCOOH in automobile exhaust (-28 ^0/ _{00} from leaded gasoline, and -48.6 ^0/ _{00} from unleaded). Further support for a biogenic source of atmospheric HCOOH came from the carbon-14 analysis of six Mount Lemmon HCOOH samples (93-113% modern carbon), using accelerator mass spectrometry. Carbon isotopic fractionation during exchange of HCOOH between the liquid and gas phases was investigated through a gas/liquid partitioning experiment. A first experimental measurement of the Henry's Law coefficient (K^{rm H}) averaged 7400 +/- 800 M/atm. Fractionation between HCOOH_{rm (g)} and HCOOH_{rm (aq)} was found to be negligible.

Johnson, Bryan Jay

419

Equilibrium absorption of carbon dioxide by amino acid salt and amine amino acid salt solutions  

Microsoft Academic Search

Experimental vapour liquid equilibrium (VLE) measurements were conducted for an amino acid salt(AAS), 3.5 M potassium sarcosinate and an amine amino acid salt (AAAS), the 5.0 M sarcosinate salt of 3-(methylamino)propylamine.The study was performed in two VLE apparatuses from 40 to 120C and for CO2 partial pressures ranging from 0.08 to 995kPa. Thermodynamic models representing the AAS and AAAS solvent

Ugochukwu E. Aronu; Erik T. Hessen; Tore Haug-Warberg; Karl A. Hoff; Hallvard F. Svendsen

2011-01-01

420

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

Fabin Surez-Garca; Amelia Martnez-Alonso; Juan M. D. Tascn

2004-01-01

421

Carbon nanotube-supported gold nanoparticles as efficient catalysts for selective oxidation of cellobiose into gluconic acid in aqueous medium.  

PubMed

Gold nanoparticles loaded on nitric acid-pretreated carbon nanotubes are efficient for the selective oxidation of cellobiose by molecular oxygen to gluconic acid in aqueous medium without pH control; a gluconic acid yield of 80% has been obtained at 145 degrees C. PMID:19921022

Tan, Xuesong; Deng, Weiping; Liu, Mi; Zhang, Qinghong; Wang, Ye

2009-10-14

422

Electrochemical evaluation of ferrocene carboxylic acids confined on surfactantclay 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 FDCCTABclayGC modified electrode showed greater stability and redox electroactivity than

Lenys Fernndez; Hermes Carrero

2005-01-01

423

Deterministic modeling of the corrosion of a low-carbon steel by carbon dioxide and the effect of acetic acid  

NASA Astrophysics Data System (ADS)

The current work is carried out with the aim of developing a deterministic model of the corrosion of low-carbon steel by carbon dioxide including the effect of acetic acid. The interaction of acetic acid with the corrosion-products layer is studied and the system is modelled by considering reactions and the transport processes within the boundary layer along with protective film formation and its dissolution. The Point Defect Model (PDM) is used to describe passive film processes using fundamental chemical reactions and physicochemical properties of the metal-film-solution interface. The underlying mechanisms for describing currents, thicknesses, impedances, and structures are based on the defect chemistry of the layers formed on the metallic surface. Ellipsometry Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Focus Ion Beam (FIB) and Electrochemical Impedance Spectroscopy (EIS) are used to determine the nature of the layers formed on the metallic surface. Transient analysis is carried out to obtain the parameters for the PDM from the impedance analysis under steady state conditions. Ellipsometry, SEM and FIB are applied for a further understanding on the composition and morphology of the film. According to Electrochemical Impedance Spectroscopy (EIS), acetic acid effect is markedly dependent upon the pH of the environment, showing a decrease in the charge transfer resistance at pH=4, and an increase of this parameter at pH=6. Acetic acid decreases the corrosion caused by dissolved carbon dioxide but its presence does not change the mechanisms of corrosion. The PDM accounts for most of the experimental observations on the structure and behavior of the films formed on the metallic surface predicting the dissolution of the oxide layer adjacent to the metal surface when the outer layer resistance is similar in magnitude to the applied potential; this is supported by experimental findings from FIB and SEM. The porosity of the outer layer, the electric field strength across the barrier layer, the polarizability of the barrier layer/outer layer interface and the standard rate constants for the point defect generation and annihilation reactions at the barrier layer interfaces, and other parameters, are found to be independent of the applied potential.

Rosas-Camacho, Omar

424

Effect of sinapic acid against carbon tetrachloride-induced acute hepatic injury in rats.  

PubMed

Acute hepatic inflammation is regarded as a hallmark of early stage fibrosis, which can progress to extensive fibrosis and cirrhosis. Sinapic acid is a phenylpropanoid compound that is abundant in cereals, nuts, oil seeds, and berries and has been reported to exhibit a wide range of pharmacological properties. In this study, we investigated the anti-inflammatory effect of sinapic acid in carbon tetrachloride (CCl4)-induced acute hepatic injury in rats. Sinapic acid was administered orally (10 or 20 mg/kg) to rats at 30 min and 16 h before CCl4 intoxication. Sinapic acid treatment of rats reduced CCl4-induced abnormalities in liver histology, serum alanine transaminase and aspartate transaminase activities, and liver malondialdehyde levels. In addition, sinapic acid treatment significantly attenuated the CCl4-induced production of inflammatory mediators, including tumor necrosis factor-alpha and interleukin-1? mRNA levels, and increased the expression of nuclear factor-kappa B (NF-?B p65). Sinapic acid exhibited strong free radical scavenging activity in vitro. Thus, sinapic acid protected the rat liver from CCl4-induced inflammation, most likely by acting as a free radical scavenger and modulator of NF-?B p65 activation and proinflammatory cytokine expression. Sinapic acid may thus have potential as a therapeutic agent for suppressing hepatic inflammation. PMID:23494565

Shin, Dong-Su; Kim, Kung Wook; Chung, Hae Young; Yoon, Sik; Moon, Jeon-Ok

2013-03-15

425

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

426

Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic  

SciTech Connect

Carbon dioxide injection into deep sea sediments below 2700 m water depth and a few hundred meters to fifteen hundred meters deep in the sediment column may provide permanent geologic storage by gravitational trapping. At high pressures and low temperatures common in deep sea sediments a few hundred meters below sea floor, CO{sub 2} will be in its liquid phase and will be denser than the overlying pore fluid. The lower density of the pore fluid provides a cap to the denser CO{sub 2} and ensures gravitational trapping in the short term. The overall storage capacity for CO{sub 2} in such deep sea formations below the ocean floor is primarily determined by the permeability, and will vary with seafloor depth, geothermal gradient, porosity, and pore water salinity. Furthermore, the dissemination of the injected CO{sub 2} in the sediments and potential chemical reactions between CO{sub 2}, pore fluid and sediments will define its fate in the storage reservoir. The main objectives of our research was to evaluate the potential for sub-seabed CO{sub 2} storage in deep sea sediments using a range of approaches including experiments, permeability analysis, and modeling. Over the course of the three-year award, our results support an important role for sub-seabed storage in a diverse portfolio of carbons sequestration options. Our analysis has shown the feasibility of this type of storage, and also emphasizes that escape or leakage from such sites would be negligible. The most difficult challenge is to overcome the low permeability of typical deep-sea sediments, and a variety of approaches are suggested for future research.

Klaus Lackner; Charles Harvey; Bruce Watson

2008-01-14

427

Emissions of formaldehyde, acetic acid, methanol, and other trace gases from biomass fires in North Carolina measured by airborne Fourier transform infrared spectroscopy  

Microsoft Academic Search

Biomass burning is an important source of many trace gases in the global troposphere. We have constructed an airborne trace gas measurement system consisting of a Fourier transform infrared spectrometer (FTIR) coupled to a ``flow-through'' multipass cell (AFTIR) and installed it on a U.S. Department of Agriculture Forest Service King Air B-90. The first measurements with the new system were

R. J. Yokelson; J. G. Goode; D. E. Ward; R. A. Susott; R. E. Babbitt; D. D. Wade; I. Bertschi; D. W. T. Griffith; W. M. Hao

1999-01-01

428

Achieving high efficiency silicon-carbon nanotube heterojunction solar cells by acid doping.  

PubMed

Various approaches to improve the efficiency of solar cells have followed the integration of nanomaterials into Si-based photovoltaic devices. Here, we achieve 13.8% efficiency solar cells by combining carbon nanotubes and Si and doping with dilute HNO(3). Acid infiltration of nanotube networks significantly boost the cell efficiency by reducing the internal resistance that improves fill factor and by forming photoelectrochemical units that enhance charge separation and transport. Compared to conventional Si cells, the fabrication process is greatly simplified, simply involving the transfer of a porous semiconductor-rich nanotube film onto an n-type crystalline Si wafer followed by acid infiltration. PMID:21452837

Jia, Yi; Cao, Anyuan; Bai, Xi; Li, Zhen; Zhang, Luhui; Guo, Ning; Wei, Jinquan; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai; Ajayan, P M

2011-03-31

429

Solid solubilities of methoxyphenylacetic acid isomer compounds in supercritical carbon dioxide  

SciTech Connect

The solid solubilities of the isomers o-, m-, and p-methoxyphenylacetic acid were measured in supercritical carbon dioxide at 308.2 K over a pressure range of 11--34 MPa. The results were correlated by the Peng-Robinson equation of state and the augmented van der Waals-density-dependent local composition equation. The data showed that solubility increased in the order of o-, p-, and m-methoxyphenylacetic acid, and the latter equation of state gave a much better correlation than the Peng-Robinson equation.

Hyungkeun Lee; Choonho Kim (Korea Inst. of Energy Research, Taejeon (Korea, Republic of). Energy and Environmental Research Dept.); Sunwook Kim (Ulsan Univ., Ulsan (Korea, Republic of). Dept. of Chemical Engineering); Cheongsong Choi (Sogang Univ., Seoul (Korea, Republic of). Dept. of Chemical Engineering)

1994-01-01

430

Pseudo-capacitance on exfoliated carbon fiber in sulfuric acid electrolyte  

NASA Astrophysics Data System (ADS)

The specific capacitance of exfoliated carbon fibers (ExCF) which were synthesized from pitch-based carbon fibers showed a strong dependence with the concentration of sulfuric acid electrolyte and reached 1.4 F/m2 in 18 M H2SO4 solution. Since the capacitance value is quite large compared with the case of conventional activated carbons, faradic reactions (charge transfer reactions) are the cause of pseudo-capacitance. ExCF, however, gave a featureless cyclic voltammogram in 18 M H2SO4 solution. In the case of exfoliated natural graphite, the intercalation of H2SO4 molecules is evidenced by redox peaks observed in the voltammograms in the same conditions. Therefore, a strong interaction between the H2SO4 molecules and the ExCF surface might be the reason for the origin of pseudo-capacitance with ExCF in H2SO4 electrolyte.

Soneda, Y.; Yamashita, J.; Kodama, M.; Hatori, H.; Toyoda, M.; Inagaki, M.

2006-03-01

431

Extraction of lanthanides from acidic solution using tributyl phosphate modified supercritical carbon dioxide  

Microsoft Academic Search

The feasibility of using supercritical carbon dioxide as a substitute extraction solvent in nuclear reprocessing was tested by the extraction of lanthanide ions from acidic solution. Lanthanides were extracted from 6 M HNO[sub 3]-3 M LiNO[sub 3] solutions using tributyl phosphate- (TBP-) modified CO[sub 2]. Synergistic effects were also investigated using a combination of thenoyltrifluoroacetone (TTA) and TBP-modified CO[sub 2

K. E. Laintz; E. Tachikawa

1994-01-01

432

The surface fractal investigation on carbon nanotubes modified by the adsorption of poly(acrylic acid)  

Microsoft Academic Search

In this paper, surface fractal analysis is carried out to study the surface of carbon nanotubes after the adsorption of poly(acrylic acid) (PAA) using the thermodynamic method. The fractal dimension (dSF ) of a fractal surface, BET surface area (SBET) and pore size distribution (PSD) are calculated from low-temperature nitrogen adsorption isotherms. The value of dSF declines as the adsorption

Qing-Feng Hou; Xian-Cai Lu; Xian-Dong Liu; Bai-Xing Hu; Ju-Qing Cui; Jian Shen

2005-01-01

433

Electronic and magnetic properties of acid-adsorbed nanoporous activated carbon fibers  

Microsoft Academic Search

Nanoporous activated carbon fibers (ACFs) feature 3D disordered networks of nanographite domains that consist of stacks of 34 nanographene sheets each. At the peripheries of the nanographene sheets, the localized spins of a nonbonding edge state are created. The magnetic properties of the edge-state spins in ACFs are investigated in relation to the interaction with acid molecules adsorbed in the

Sijia Hao; Kazuyuki Takai; Feiyu Kang; Toshiaki Enoki

2008-01-01

434

Thermal decomposition of dimethoxymethane and dimethyl carbonate catalyzed by solid acids and bases  

Microsoft Academic Search

The thermal decomposition of dimethoxymethane (DMM) and dimethyl carbonate (DMC) on MgO, H-ZSM-5, SiO2, ?-Al2O3 and ZnO was studied using a fixed bed isothermal reactor equipped with an online gas chromatograph. It was found that DMM was stable on MgO at temperatures up to 623K, while it was decomposed over the acidic H-ZSM-5 with 99% conversion at 423K. On the

Yuchuan Fu; Haiyan Zhu; Jianyi Shen

2005-01-01

435

Porosity development in activated carbons obtained from date pits under chemical activation with phosphoric acid  

Microsoft Academic Search

Date pits, a low-cost agricultural by-product, was tested as a precursor for the production of porous carbons in a chemical scheme using phosphoric acid. The raw material was impregnated with increasing concentrations of H3PO4 (3070 vol.%) followed by pyrolysis at 300, 500 or 700 C. Texture characteristics of the products were determined by adsorption of N2 at 77 K, as

Badie S. Girgis; Abdel-Nasser A. El-Hendawy

2002-01-01

436

Effects of alginic acid from marine algae on calcium carbonate electrodeposited coating  

Microsoft Academic Search

The effect of alginic acid, extracted from the Lessonia trabeculata calcareous marine algae, was studied in the electrocrystallization of calcium carbonate (CaCO3) on indium tin oxide (ITO) transparent electrodes. Scanning electron microscopy, X-ray diffraction-collected data and microscopic observations show that the presence of Mg2+ at the electrolyte induces the magnesium calcite and aragonite phase formation along with the changes in

Jorge Pavez; Juan F. Silva; Francisco Melo

2005-01-01

437

Protective effect of caffeic acid phenethyl ester against carbon tetrachloride-induced hepatotoxicity in mice  

Microsoft Academic Search

This study was designed to investigate the protective effects of the phenethyl ester of caffeic acid (CAPE) against carbon tetrachoride (CCl4)-induced hepatotoxicities in mice. Pretreatment with CAPE prior to administration of CCl4 significantly prevented the increases in serum alanine, aspartate aminotransferase and alkaline phosphatase activities, hepatic lipid peroxidation formation, and depletion of glutathione content. In addition, CAPE prevented CCl4-induced apoptosis

Kyung Jin Lee; Jae Ho Choi; Tilak Khanal; Yong Pil Hwang; Young Chul Chung; Hye Gwang Jeong

2008-01-01

438

Chlorogenic acid against carbon tetrachloride-induced liver fibrosis in rats  

Microsoft Academic Search

This study examined the effects of chlorogenic acid (CGA) on liver fibrosis induced by carbon tetrachloride (CCl4) and explored the possible mechanisms of action. Liver fibrosis was induced in male SpragueDawley (SD) rats by the injection of 40% CCl4 subcutaneously twice a week for eight weeks. At the same time, CGA (60 and 30mg\\/kg) was administered intragastrically once daily to

Hongyang Shi; Lei Dong; Yanhua Bai; Juhui Zhao; Yong Zhang; Li Zhang

2009-01-01

439

Catalytic ozonation of phenol and oxalic acid with copper-loaded activated carbon  

Microsoft Academic Search

A novel heterogeneous catalytic ozonation process in water treatment was studied, with a copper-loaded activated carbon (Cu\\/AC)\\u000a that was prepared by an incipient wetness impregnation method at low temperature and tested as a catalyst in the ozonation\\u000a of phenol and oxalic acid. Cu\\/AC was characterized using XRD, BET and SEM techniques. Compared with ozonation alone, the presence\\u000a of Cu\\/AC in

Yi-fei Rao; Han-jin Luo; Chao-hai Wei; Ling-feng Luo

2010-01-01

440

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

441

Influence of sodium azide on the removal of fulvic acids by activated carbon  

Microsoft Academic Search

The impact of sodium azide, as an inhibitor of biochemical reactions in aqueous solutions, on its interaction with activated\\u000a carbon (AC) and on the characteristics of equilibrium adsorption of fulvic acids (FA) on AC has been studied. It was shown\\u000a that additions of sodium azide during FA adsorption on AC under equilibrium conditions do not completely inhibit the biological\\u000a activity

N. A. Klimenko; T. V. Polyakova; L. A. Savchina

2010-01-01

442

Acid dissolution experiments - Carbonates and the 6.8-micrometer bands in interplanetary dust particles  

NASA Astrophysics Data System (ADS)

A chemical dissolution experiment on an interplanetary dust particle (IDP) showed that carbonates, not acid-insoluble organic compounds, were responsible for virtually all the absorption at 6.8 micrometers seen in the infrared spectra of this particle. The IDP examined had an infrared spectrum characteristic of layer-lattice silicates and belongs to a class of IDP's whose spectra resemble those of protostellar objects like W33 A, which also exhibit a band at 6.8 micrometers.

Sandford, S. A.

1986-03-01

443

Activated carbons prepared from rice hull by one-step phosphoric acid activation  

Microsoft Academic Search

Activated carbons were prepared from rice hull by one-step phosphoric acid activation in this work. The evolution of pore structure and surface chemistry in the activation temperature range of 170450C was investigated through various characterization techniques. The results showed that the development of porosity (extent of activation) was negligible at activation temperature below 300C, and rapid evolution occurred in 300400C.

Yanping Guo; David A. Rockstraw

2007-01-01

444

A synergistic effect between zinc salt and phosphonic acid for corrosion inhibition of a carbon steel  

Microsoft Academic Search

This work is devoted to the corrosion inhibition of a carbon steel by a zinc salt\\/phosphonic acid association. Steady-state current-voltage curves and electrochemical impedance measurements carried out in the presence of each compound and for the mixture show a synergistic effect between the two molecules. The concentrations of the compounds in the mixture were lower than the concentrations used for

Y. Gonzalez; M. C. Lafont; N. Pebere; F. Moran

1996-01-01

445

Corrosion inhibition of carbon steel in sulfuric acid by bicyclic isoxazolidines  

Microsoft Academic Search

The cycloaddition of cyclic nitrone1-pyrroline-1-oxide with 1-dodecene and 1-hexadecene afford a bicyclic (isoxazolidines). These isoxazolidines were tested for corrosion inhibition of carbon steel in 1N H2SO4 in the 30-60C temperature range by gravimetric and electrochemical methods. The compound isoxazolidines exhibited excellent inhibition efficiency in the acidic corrosion environment. The presence of heteroatoms such as N and O induce greater adsorption

M. Tariq Saeed

2004-01-01

446

Some ethoxylated fatty acids as corrosion inhibitors for low carbon steel in formation water  

Microsoft Academic Search

A series of ethoxylated fatty acids have been studied in order to evaluate their effect on the corrosion inhibition of low carbon steel. The behavior of these compounds is illustrated by the adsorption isotherms and weight loss measurements. The adsorption isotherms for saturated samples Pa(EO)80 and St(EO)80 exhibit an L-shaped isotherms while the unsaturated samples Ol(EO)80, Li(EO)80, and Soy(EO)80 show

M. M Osman; M. N Shalaby

2003-01-01

447

Gallic acid as a corrosion inhibitor of carbon steel in chemical decontamination formulation  

Microsoft Academic Search

Gallic acid (GA) was found to provide corrosion inhibition to carbon steel (CS) at 4.25mM concentration. Inherent stability to radiation degradation as compared to other reductant and coupled with its anionic nature with respect to removal using ion exchange column makes it suitable for using as both reductant as well as corrosion inhibitor in dilute decontamination formulations operating in the

S. J. Keny; A. G. Kumbhar; C. Thinaharan; G. Venkateswaran

2008-01-01

448

Inhibitory mechanism of low-carbon steel corrosion by mimosa tannin in sulphuric acid solutions  

Microsoft Academic Search

Mimosa tannin was investigated as inhibitor of low-carbon steel sulphuric acid corrosion in concentrations from 10-5 to 10-1 mol L-1, at the temperature of 298 K in the solutions of pH 1, 2 and 3. The inhibitor effectiveness increases with increase in concentration. The adsorptive behaviour of mimosa tannin in solutions of pH 1 and 2 may be approximated, both

S. Martinez; I. tern

2001-01-01